Publications - Lehrstuhl für Biotechnologie und Biophysik

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2022[ to top ]

Glucose and Inositol Transporters, SLC5A1 and SLC5A3, in Glioblastoma Cell Migration Brosch, Philippa K.; Korsa, Tessa; Taban, Danush; Eiring, Patrick; Hildebrand, Sascha; Neubauer, Julia; Zimmermann, Heiko; Sauer, Markus; Shirakashi, Ryo; Djuzenova, Cholpon S.; Sisario, Dmitri; Sukhorukov, Vladimir L. in Cancers (2022). 14 5794.
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(1) Background: The recurrence of glioblastoma multiforme (GBM) is mainly due to invasion of the surrounding brain tissue, where organic solutes, including glucose and inositol, are abundant. Invasive cell migration has been linked to the aberrant expression of transmembrane solute-linked carriers (SLC). Here, we explore the role of glucose (SLC5A1) and inositol transporters (SLC5A3) in GBM cell migration. (2) Methods: Using immunofluorescence microscopy, we visualized the subcellular localization of SLC5A1 and SLC5A3 in two highly motile human GBM cell lines. We also employed wound-healing assays to examine the effect of SLC inhibition on GBM cell migration and examined the chemotactic potential of inositol. (3) Results: While GBM cell migration was significantly increased by extracellular inositol and glucose, it was strongly impaired by SLC transporter inhibition. In the GBM cell monolayers, both SLCs were exclusively detected in the migrating cells at the monolayer edge. In single GBM cells, both transporters were primarily localized at the leading edge of the lamellipodium. Interestingly, in GBM cells migrating via blebbing, SLC5A1 and SLC5A3 were predominantly detected in nascent and mature blebs, respectively. (4) Conclusion: We provide several lines of evidence for the involvement of SLC5A1 and SLC5A3 in GBM cell migration, thereby complementing the migration-associated transportome. Our findings suggest that SLC inhibition is a promising approach to GBM treatment.

@article{brosch2022glucose, abstract = {(1) Background: The recurrence of glioblastoma multiforme (GBM) is mainly due to invasion of the surrounding brain tissue, where organic solutes, including glucose and inositol, are abundant. Invasive cell migration has been linked to the aberrant expression of transmembrane solute-linked carriers (SLC). Here, we explore the role of glucose (SLC5A1) and inositol transporters (SLC5A3) in GBM cell migration. (2) Methods: Using immunofluorescence microscopy, we visualized the subcellular localization of SLC5A1 and SLC5A3 in two highly motile human GBM cell lines. We also employed wound-healing assays to examine the effect of SLC inhibition on GBM cell migration and examined the chemotactic potential of inositol. (3) Results: While GBM cell migration was significantly increased by extracellular inositol and glucose, it was strongly impaired by SLC transporter inhibition. In the GBM cell monolayers, both SLCs were exclusively detected in the migrating cells at the monolayer edge. In single GBM cells, both transporters were primarily localized at the leading edge of the lamellipodium. Interestingly, in GBM cells migrating via blebbing, SLC5A1 and SLC5A3 were predominantly detected in nascent and mature blebs, respectively. (4) Conclusion: We provide several lines of evidence for the involvement of SLC5A1 and SLC5A3 in GBM cell migration, thereby complementing the migration-associated transportome. Our findings suggest that SLC inhibition is a promising approach to GBM treatment.}, author = {Brosch, Philippa K. and Korsa, Tessa and Taban, Danush and Eiring, Patrick and Hildebrand, Sascha and Neubauer, Julia and Zimmermann, Heiko and Sauer, Markus and Shirakashi, Ryo and Djuzenova, Cholpon S. and Sisario, Dmitri and Sukhorukov, Vladimir L.}, journal = {Cancers}, keywords = {vladimir}, pages = 5794, series = 23, title = {Glucose and Inositol Transporters, SLC5A1 and SLC5A3, in Glioblastoma Cell Migration}, volume = 14, year = 2022 }

%0 Journal Article %1 brosch2022glucose %A Brosch, Philippa K. %A Korsa, Tessa %A Taban, Danush %A Eiring, Patrick %A Hildebrand, Sascha %A Neubauer, Julia %A Zimmermann, Heiko %A Sauer, Markus %A Shirakashi, Ryo %A Djuzenova, Cholpon S. %A Sisario, Dmitri %A Sukhorukov, Vladimir L. %B 23 %D 2022 %J Cancers %P 5794 %T Glucose and Inositol Transporters, SLC5A1 and SLC5A3, in Glioblastoma Cell Migration %U https://www.mdpi.com/2072-6694/14/23/5794 %V 14 %X (1) Background: The recurrence of glioblastoma multiforme (GBM) is mainly due to invasion of the surrounding brain tissue, where organic solutes, including glucose and inositol, are abundant. Invasive cell migration has been linked to the aberrant expression of transmembrane solute-linked carriers (SLC). Here, we explore the role of glucose (SLC5A1) and inositol transporters (SLC5A3) in GBM cell migration. (2) Methods: Using immunofluorescence microscopy, we visualized the subcellular localization of SLC5A1 and SLC5A3 in two highly motile human GBM cell lines. We also employed wound-healing assays to examine the effect of SLC inhibition on GBM cell migration and examined the chemotactic potential of inositol. (3) Results: While GBM cell migration was significantly increased by extracellular inositol and glucose, it was strongly impaired by SLC transporter inhibition. In the GBM cell monolayers, both SLCs were exclusively detected in the migrating cells at the monolayer edge. In single GBM cells, both transporters were primarily localized at the leading edge of the lamellipodium. Interestingly, in GBM cells migrating via blebbing, SLC5A1 and SLC5A3 were predominantly detected in nascent and mature blebs, respectively. (4) Conclusion: We provide several lines of evidence for the involvement of SLC5A1 and SLC5A3 in GBM cell migration, thereby complementing the migration-associated transportome. Our findings suggest that SLC inhibition is a promising approach to GBM treatment.
Candida albicans Induces Cross-Kingdom miRNA Trafficking in Human Monocytes To Promote Fungal Growth Halder, Luke D.; Babych, Svitlana; Palme, Diana I.; Mansouri-Ghahnavieh, Elham; Ivanov, Lia; Ashonibare, Victory; Langenhorst, Daniela; Prusty, Bhupesh; Rambach, Günter; Wich, Melissa; Trinks, Nora; Blango, Matthew G.; Kornitzer, Daniel; Terpitz, Ulrich; Speth, Cornelia; Jungnickel, Berit; Beyersdorf, Niklas; Zipfel, Peter F.; Brakhage, Axel A.; Skerka, Christine; Lorenz, Michael in mBio (2022). 13 e03563–21.
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Over the last decade, communication between immune cells by extracellular vesicle-associated miRNAs has emerged as an important regulator of the coordinated immune response. Therefore, a thorough understanding of the conversation occurring via miRNAs, especially during infection, may provide novel insights into both the host reaction to the microbe as well as the microbial response. In response to infections, human immune cells release extracellular vesicles (EVs) that carry a situationally adapted cocktail of proteins and nucleic acids, including microRNAs (miRNAs), to coordinate the immune response. In this study, we identified hsa-miR-21-5p and hsa-miR-24-3p as the most common miRNAs in exosomes released by human monocytes in response to the pathogenic fungus Candida albicans. Functional analysis of miRNAs revealed that hsa-miR-24-3p, but not hsa-miR-21-5p, acted across species and kingdoms, entering C. albicans and inducing fungal cell growth by inhibiting translation of the cyclin-dependent kinase inhibitor Sol1. Packaging of hsa-miR-24-3p into monocyte exosomes required binding of fungal soluble β-glucan to complement receptor 3 (CR3) and binding of mannan to Toll-like receptor 4 (TLR4), resulting in receptor colocalization. Together, our in vitro and in vivo findings reveal a novel cross-species evasion mechanism by which C. albicans exploits a human miRNA to promote fungal growth and survival in the host. IMPORTANCE Over the last decade, communication between immune cells by extracellular vesicle-associated miRNAs has emerged as an important regulator of the coordinated immune response. Therefore, a thorough understanding of the conversation occurring via miRNAs, especially during infection, may provide novel insights into both the host reaction to the microbe as well as the microbial response. This study provides evidence that the pathogenic fungus C. albicans communicates with human monocytes and induces the release of a human miRNA that promotes fungal growth. This mechanism represents an unexpected cross-species interaction and implies that an inhibition of specific miRNAs offers new possibilities for the treatment of human fungal infections.

@article{halder2022candida, abstract = {Over the last decade, communication between immune cells by extracellular vesicle-associated miRNAs has emerged as an important regulator of the coordinated immune response. Therefore, a thorough understanding of the conversation occurring via miRNAs, especially during infection, may provide novel insights into both the host reaction to the microbe as well as the microbial response. In response to infections, human immune cells release extracellular vesicles (EVs) that carry a situationally adapted cocktail of proteins and nucleic acids, including microRNAs (miRNAs), to coordinate the immune response. In this study, we identified hsa-miR-21-5p and hsa-miR-24-3p as the most common miRNAs in exosomes released by human monocytes in response to the pathogenic fungus Candida albicans. Functional analysis of miRNAs revealed that hsa-miR-24-3p, but not hsa-miR-21-5p, acted across species and kingdoms, entering C. albicans and inducing fungal cell growth by inhibiting translation of the cyclin-dependent kinase inhibitor Sol1. Packaging of hsa-miR-24-3p into monocyte exosomes required binding of fungal soluble β-glucan to complement receptor 3 (CR3) and binding of mannan to Toll-like receptor 4 (TLR4), resulting in receptor colocalization. Together, our in vitro and in vivo findings reveal a novel cross-species evasion mechanism by which C. albicans exploits a human miRNA to promote fungal growth and survival in the host. IMPORTANCE Over the last decade, communication between immune cells by extracellular vesicle-associated miRNAs has emerged as an important regulator of the coordinated immune response. Therefore, a thorough understanding of the conversation occurring via miRNAs, especially during infection, may provide novel insights into both the host reaction to the microbe as well as the microbial response. This study provides evidence that the pathogenic fungus C. albicans communicates with human monocytes and induces the release of a human miRNA that promotes fungal growth. This mechanism represents an unexpected cross-species interaction and implies that an inhibition of specific miRNAs offers new possibilities for the treatment of human fungal infections.}, author = {Halder, Luke D. and Babych, Svitlana and Palme, Diana I. and Mansouri-Ghahnavieh, Elham and Ivanov, Lia and Ashonibare, Victory and Langenhorst, Daniela and Prusty, Bhupesh and Rambach, Günter and Wich, Melissa and Trinks, Nora and Blango, Matthew G. and Kornitzer, Daniel and Terpitz, Ulrich and Speth, Cornelia and Jungnickel, Berit and Beyersdorf, Niklas and Zipfel, Peter F. and Brakhage, Axel A. and Skerka, Christine and Lorenz, Michael}, journal = {mBio}, keywords = {terpitz}, pages = {e03563-21}, series = 1, title = {Candida albicans Induces Cross-Kingdom miRNA Trafficking in Human Monocytes To Promote Fungal Growth}, volume = 13, year = 2022 }

%0 Journal Article %1 halder2022candida %A Halder, Luke D. %A Babych, Svitlana %A Palme, Diana I. %A Mansouri-Ghahnavieh, Elham %A Ivanov, Lia %A Ashonibare, Victory %A Langenhorst, Daniela %A Prusty, Bhupesh %A Rambach, Günter %A Wich, Melissa %A Trinks, Nora %A Blango, Matthew G. %A Kornitzer, Daniel %A Terpitz, Ulrich %A Speth, Cornelia %A Jungnickel, Berit %A Beyersdorf, Niklas %A Zipfel, Peter F. %A Brakhage, Axel A. %A Skerka, Christine %A Lorenz, Michael %B 1 %D 2022 %J mBio %P e03563-21 %T Candida albicans Induces Cross-Kingdom miRNA Trafficking in Human Monocytes To Promote Fungal Growth %U https://journals.asm.org/doi/abs/10.1128/mbio.03563-21 %V 13 %X Over the last decade, communication between immune cells by extracellular vesicle-associated miRNAs has emerged as an important regulator of the coordinated immune response. Therefore, a thorough understanding of the conversation occurring via miRNAs, especially during infection, may provide novel insights into both the host reaction to the microbe as well as the microbial response. In response to infections, human immune cells release extracellular vesicles (EVs) that carry a situationally adapted cocktail of proteins and nucleic acids, including microRNAs (miRNAs), to coordinate the immune response. In this study, we identified hsa-miR-21-5p and hsa-miR-24-3p as the most common miRNAs in exosomes released by human monocytes in response to the pathogenic fungus Candida albicans. Functional analysis of miRNAs revealed that hsa-miR-24-3p, but not hsa-miR-21-5p, acted across species and kingdoms, entering C. albicans and inducing fungal cell growth by inhibiting translation of the cyclin-dependent kinase inhibitor Sol1. Packaging of hsa-miR-24-3p into monocyte exosomes required binding of fungal soluble β-glucan to complement receptor 3 (CR3) and binding of mannan to Toll-like receptor 4 (TLR4), resulting in receptor colocalization. Together, our in vitro and in vivo findings reveal a novel cross-species evasion mechanism by which C. albicans exploits a human miRNA to promote fungal growth and survival in the host. IMPORTANCE Over the last decade, communication between immune cells by extracellular vesicle-associated miRNAs has emerged as an important regulator of the coordinated immune response. Therefore, a thorough understanding of the conversation occurring via miRNAs, especially during infection, may provide novel insights into both the host reaction to the microbe as well as the microbial response. This study provides evidence that the pathogenic fungus C. albicans communicates with human monocytes and induces the release of a human miRNA that promotes fungal growth. This mechanism represents an unexpected cross-species interaction and implies that an inhibition of specific miRNAs offers new possibilities for the treatment of human fungal infections.
The Photoreaction of the Proton-Pumping Rhodopsin 1 From the Maize Pathogenic Basidiomycete Ustilago maydis La Greca, Mariafrancesca; Chen, Jheng-Liang; Schubert, Luiz; Kozuch, Jacek; Berneiser, Tim; Terpitz, Ulrich; Heberle, Joachim; Schlesinger, Ramona in Frontiers in Molecular Biosciences (2022). 9
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Microbial rhodopsins have recently been discovered in pathogenic fungi and have been postulated to be involved in signaling during the course of an infection. Here, we report on the spectroscopic characterization of a light-driven proton pump rhodopsin (UmRh1) from the smut pathogen Ustilago maydis, the causative agent of tumors in maize plants. Electrophysiology, time-resolved UV/Vis and vibrational spectroscopy indicate a pH-dependent photocycle. We also characterized the impact of the auxin hormone indole-3-acetic acid that was shown to influence the pump activity of UmRh1 on individual photocycle intermediates. A facile pumping activity test was established of UmRh1 expressed in Pichia pastoris cells, for probing proton pumping out of the living yeast cells during illumination. We show similarities and distinct differences to the well-known bacteriorhodopsin from archaea and discuss the putative role of UmRh1 in pathogenesis.

@article{lagreca2022photoreaction, abstract = {Microbial rhodopsins have recently been discovered in pathogenic fungi and have been postulated to be involved in signaling during the course of an infection. Here, we report on the spectroscopic characterization of a light-driven proton pump rhodopsin (UmRh1) from the smut pathogen Ustilago maydis, the causative agent of tumors in maize plants. Electrophysiology, time-resolved UV/Vis and vibrational spectroscopy indicate a pH-dependent photocycle. We also characterized the impact of the auxin hormone indole-3-acetic acid that was shown to influence the pump activity of UmRh1 on individual photocycle intermediates. A facile pumping activity test was established of UmRh1 expressed in Pichia pastoris cells, for probing proton pumping out of the living yeast cells during illumination. We show similarities and distinct differences to the well-known bacteriorhodopsin from archaea and discuss the putative role of UmRh1 in pathogenesis.}, author = {La Greca, Mariafrancesca and Chen, Jheng-Liang and Schubert, Luiz and Kozuch, Jacek and Berneiser, Tim and Terpitz, Ulrich and Heberle, Joachim and Schlesinger, Ramona}, journal = {Frontiers in Molecular Biosciences}, keywords = {terpitz}, title = {The Photoreaction of the Proton-Pumping Rhodopsin 1 From the Maize Pathogenic Basidiomycete Ustilago maydis}, volume = 9, year = 2022 }

%0 Journal Article %1 lagreca2022photoreaction %A La Greca, Mariafrancesca %A Chen, Jheng-Liang %A Schubert, Luiz %A Kozuch, Jacek %A Berneiser, Tim %A Terpitz, Ulrich %A Heberle, Joachim %A Schlesinger, Ramona %D 2022 %J Frontiers in Molecular Biosciences %T The Photoreaction of the Proton-Pumping Rhodopsin 1 From the Maize Pathogenic Basidiomycete Ustilago maydis %U https://www.frontiersin.org/article/10.3389/fmolb.2022.826990 %V 9 %X Microbial rhodopsins have recently been discovered in pathogenic fungi and have been postulated to be involved in signaling during the course of an infection. Here, we report on the spectroscopic characterization of a light-driven proton pump rhodopsin (UmRh1) from the smut pathogen Ustilago maydis, the causative agent of tumors in maize plants. Electrophysiology, time-resolved UV/Vis and vibrational spectroscopy indicate a pH-dependent photocycle. We also characterized the impact of the auxin hormone indole-3-acetic acid that was shown to influence the pump activity of UmRh1 on individual photocycle intermediates. A facile pumping activity test was established of UmRh1 expressed in Pichia pastoris cells, for probing proton pumping out of the living yeast cells during illumination. We show similarities and distinct differences to the well-known bacteriorhodopsin from archaea and discuss the putative role of UmRh1 in pathogenesis.
Vicia faba TPC1, a genetically encoded variant of the vacuole Two Pore Channel 1, is hyperexcitable Lu, Jinping; Dreyer, Ingo; Dickinson, Miles Sasha; Panzer, Sabine; Jaslan, Dawid; Navarro-Retamal, Carlos; Geiger, Dietmar; Terpitz, Ulrich; Becker, Dirk; Stroud, Robert M.; Marten, Irene; Hedrich, Rainer in bioRxiv (2022). 2021.12.22.473873-.
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To fire action-potential-like electrical signals, the vacuole membrane requires the depolarization-activated two-pore channel TPC1, also called Slowly activating Vacuolar SV channel. The TPC1/SV channel, encoded by the TPC1 gene, functions as a voltage-dependent and Ca2+-regulated potassium channel. TPC1 currents are activated by a rise in cytoplasmic Ca2+ but inhibited by luminal Ca2+. In search for species-dependent functional TPC1 channel variants, we studied polymorphic amino acids contributing to luminal Ca2+ sensitivity. We found that the acidic residues E457, E605 and D606 of the Ca2+-sensitive Arabidopsis AtTPC1 channel were neutralized by either asparagine or alanine in Vicia faba and many other Fabaceae as well. When expressed in the Arabidopsis loss-of-AtTPC1 function background, the wild type VfTPC1 was hypersensitive to vacuole depolarization and insensitive to blocking luminal Ca2+. When AtTPC1 was mutated for the three VfTPC1-homologous polymorphic site residues, the Arabidopsis At-VfTPC1 channel mutant gained VfTPC1-like voltage and luminal Ca2+ insensitivity that together made vacuoles hyperexcitable. These findings indicate that natural TPC1 channel variants in plant families exist which differ in vacuole excitability and very likely respond to changes in environmental settings of their ecological niche.Significance statement Vacuolar electrical excitability and stress-related Ca2+ signaling depends on the activity of the vacuolar cation channel TPC1. Until now, the regulatory features of AtTPC1 from the model plant Arabidopsis thaliana was believed to apply to the TPC1 channels of other species. However, here we now show that, surprisingly, the VfTPC1 channel of the economic broad bean, in contrast to AtTPC1, proves to be hyperactive and confers hyperexcitability to the vacuole. The different gating behavior is most likely related to an impaired Ca2+ sensor site in the vacuolar pore vestibule, rising the probability to open at more negative membrane voltages. These natural variants of the TPC1 channel could help the plant adapt and respond to environmental challenges.Competing Interest StatementThe authors have declared no competing interest.

@article{lu2022ltemgtvicia, abstract = {To fire action-potential-like electrical signals, the vacuole membrane requires the depolarization-activated two-pore channel TPC1, also called Slowly activating Vacuolar SV channel. The TPC1/SV channel, encoded by the TPC1 gene, functions as a voltage-dependent and Ca2+-regulated potassium channel. TPC1 currents are activated by a rise in cytoplasmic Ca2+ but inhibited by luminal Ca2+. In search for species-dependent functional TPC1 channel variants, we studied polymorphic amino acids contributing to luminal Ca2+ sensitivity. We found that the acidic residues E457, E605 and D606 of the Ca2+-sensitive Arabidopsis AtTPC1 channel were neutralized by either asparagine or alanine in Vicia faba and many other Fabaceae as well. When expressed in the Arabidopsis loss-of-AtTPC1 function background, the wild type VfTPC1 was hypersensitive to vacuole depolarization and insensitive to blocking luminal Ca2+. When AtTPC1 was mutated for the three VfTPC1-homologous polymorphic site residues, the Arabidopsis At-VfTPC1 channel mutant gained VfTPC1-like voltage and luminal Ca2+ insensitivity that together made vacuoles hyperexcitable. These findings indicate that natural TPC1 channel variants in plant families exist which differ in vacuole excitability and very likely respond to changes in environmental settings of their ecological niche.Significance statement Vacuolar electrical excitability and stress-related Ca2+ signaling depends on the activity of the vacuolar cation channel TPC1. Until now, the regulatory features of AtTPC1 from the model plant Arabidopsis thaliana was believed to apply to the TPC1 channels of other species. However, here we now show that, surprisingly, the VfTPC1 channel of the economic broad bean, in contrast to AtTPC1, proves to be hyperactive and confers hyperexcitability to the vacuole. The different gating behavior is most likely related to an impaired Ca2+ sensor site in the vacuolar pore vestibule, rising the probability to open at more negative membrane voltages. These natural variants of the TPC1 channel could help the plant adapt and respond to environmental challenges.Competing Interest StatementThe authors have declared no competing interest.}, author = {Lu, Jinping and Dreyer, Ingo and Dickinson, Miles Sasha and Panzer, Sabine and Jaslan, Dawid and Navarro-Retamal, Carlos and Geiger, Dietmar and Terpitz, Ulrich and Becker, Dirk and Stroud, Robert M. and Marten, Irene and Hedrich, Rainer}, journal = {bioRxiv}, keywords = {terpitz}, month = {jan}, pages = {2021.12.22.473873–}, title = {Vicia faba TPC1, a genetically encoded variant of the vacuole Two Pore Channel 1, is hyperexcitable}, year = 2022 }

%0 Journal Article %1 lu2022ltemgtvicia %A Lu, Jinping %A Dreyer, Ingo %A Dickinson, Miles Sasha %A Panzer, Sabine %A Jaslan, Dawid %A Navarro-Retamal, Carlos %A Geiger, Dietmar %A Terpitz, Ulrich %A Becker, Dirk %A Stroud, Robert M. %A Marten, Irene %A Hedrich, Rainer %D 2022 %J bioRxiv %P 2021.12.22.473873-- %R 10.1101/2021.12.22.473873 %T Vicia faba TPC1, a genetically encoded variant of the vacuole Two Pore Channel 1, is hyperexcitable %U http://biorxiv.org/content/early/2022/03/04/2021.12.22.473873.abstract %X To fire action-potential-like electrical signals, the vacuole membrane requires the depolarization-activated two-pore channel TPC1, also called Slowly activating Vacuolar SV channel. The TPC1/SV channel, encoded by the TPC1 gene, functions as a voltage-dependent and Ca2+-regulated potassium channel. TPC1 currents are activated by a rise in cytoplasmic Ca2+ but inhibited by luminal Ca2+. In search for species-dependent functional TPC1 channel variants, we studied polymorphic amino acids contributing to luminal Ca2+ sensitivity. We found that the acidic residues E457, E605 and D606 of the Ca2+-sensitive Arabidopsis AtTPC1 channel were neutralized by either asparagine or alanine in Vicia faba and many other Fabaceae as well. When expressed in the Arabidopsis loss-of-AtTPC1 function background, the wild type VfTPC1 was hypersensitive to vacuole depolarization and insensitive to blocking luminal Ca2+. When AtTPC1 was mutated for the three VfTPC1-homologous polymorphic site residues, the Arabidopsis At-VfTPC1 channel mutant gained VfTPC1-like voltage and luminal Ca2+ insensitivity that together made vacuoles hyperexcitable. These findings indicate that natural TPC1 channel variants in plant families exist which differ in vacuole excitability and very likely respond to changes in environmental settings of their ecological niche.Significance statement Vacuolar electrical excitability and stress-related Ca2+ signaling depends on the activity of the vacuolar cation channel TPC1. Until now, the regulatory features of AtTPC1 from the model plant Arabidopsis thaliana was believed to apply to the TPC1 channels of other species. However, here we now show that, surprisingly, the VfTPC1 channel of the economic broad bean, in contrast to AtTPC1, proves to be hyperactive and confers hyperexcitability to the vacuole. The different gating behavior is most likely related to an impaired Ca2+ sensor site in the vacuolar pore vestibule, rising the probability to open at more negative membrane voltages. These natural variants of the TPC1 channel could help the plant adapt and respond to environmental challenges.Competing Interest StatementThe authors have declared no competing interest.
Contraction of the rigor actomyosin complex drives bulk hemoglobin expulsion from hemolyzing erythrocytes Shirakashi, Ryo; Sisario, Dmitri; Taban, Danush; Korsa, Tessa; Wanner, Sophia B.; Neubauer, Julia; Djuzenova, Cholpon S.; Zimmermann, Heiko; Sukhorukov, Vladimir L. in Biomechanics and Modeling in Mechanobiology (2022).
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Erythrocyte ghost formation via hemolysis is a key event in the physiological clearance of senescent red blood cells (RBCs) in the spleen. The turnover rate of millions of RBCs per second necessitates a rapid efflux of hemoglobin (Hb) from RBCs by a not yet identified mechanism. Using high-speed video-microscopy of isolated RBCs, we show that electroporation-induced efflux of cytosolic ATP and other small solutes leads to transient cell shrinkage and echinocytosis, followed by osmotic swelling to the critical hemolytic volume. The onset of hemolysis coincided with a sudden self-propelled cell motion, accompanied by cell contraction and Hb-jet ejection. Our biomechanical model, which relates the Hb-jet-driven cell motion to the cytosolic pressure generation via elastic contraction of the RBC membrane, showed that the contributions of the bilayer and the bilayer-anchored spectrin cytoskeleton to the hemolytic cell motion are negligible. Consistent with the biomechanical analysis, our biochemical experiments, involving extracellular ATP and the myosin inhibitor blebbistatin, identify the low abundant non-muscle myosin 2A (NM2A) as the key contributor to the Hb-jet emission and fast hemolytic cell motion. Thus, our data reveal a rapid myosin-based mechanism of hemolysis, as opposed to a much slower diffusive Hb efflux.

@article{shirakashi2022contraction, abstract = {Erythrocyte ghost formation via hemolysis is a key event in the physiological clearance of senescent red blood cells (RBCs) in the spleen. The turnover rate of millions of RBCs per second necessitates a rapid efflux of hemoglobin (Hb) from RBCs by a not yet identified mechanism. Using high-speed video-microscopy of isolated RBCs, we show that electroporation-induced efflux of cytosolic ATP and other small solutes leads to transient cell shrinkage and echinocytosis, followed by osmotic swelling to the critical hemolytic volume. The onset of hemolysis coincided with a sudden self-propelled cell motion, accompanied by cell contraction and Hb-jet ejection. Our biomechanical model, which relates the Hb-jet-driven cell motion to the cytosolic pressure generation via elastic contraction of the RBC membrane, showed that the contributions of the bilayer and the bilayer-anchored spectrin cytoskeleton to the hemolytic cell motion are negligible. Consistent with the biomechanical analysis, our biochemical experiments, involving extracellular ATP and the myosin inhibitor blebbistatin, identify the low abundant non-muscle myosin 2A (NM2A) as the key contributor to the Hb-jet emission and fast hemolytic cell motion. Thus, our data reveal a rapid myosin-based mechanism of hemolysis, as opposed to a much slower diffusive Hb efflux.}, author = {Shirakashi, Ryo and Sisario, Dmitri and Taban, Danush and Korsa, Tessa and Wanner, Sophia B. and Neubauer, Julia and Djuzenova, Cholpon S. and Zimmermann, Heiko and Sukhorukov, Vladimir L.}, journal = {Biomechanics and Modeling in Mechanobiology}, keywords = {vladimir}, title = {Contraction of the rigor actomyosin complex drives bulk hemoglobin expulsion from hemolyzing erythrocytes}, year = 2022 }

%0 Journal Article %1 shirakashi2022contraction %A Shirakashi, Ryo %A Sisario, Dmitri %A Taban, Danush %A Korsa, Tessa %A Wanner, Sophia B. %A Neubauer, Julia %A Djuzenova, Cholpon S. %A Zimmermann, Heiko %A Sukhorukov, Vladimir L. %D 2022 %J Biomechanics and Modeling in Mechanobiology %R 10.1007/s10237-022-01654-6 %T Contraction of the rigor actomyosin complex drives bulk hemoglobin expulsion from hemolyzing erythrocytes %U https://doi.org/10.1007/s10237-022-01654-6 %X Erythrocyte ghost formation via hemolysis is a key event in the physiological clearance of senescent red blood cells (RBCs) in the spleen. The turnover rate of millions of RBCs per second necessitates a rapid efflux of hemoglobin (Hb) from RBCs by a not yet identified mechanism. Using high-speed video-microscopy of isolated RBCs, we show that electroporation-induced efflux of cytosolic ATP and other small solutes leads to transient cell shrinkage and echinocytosis, followed by osmotic swelling to the critical hemolytic volume. The onset of hemolysis coincided with a sudden self-propelled cell motion, accompanied by cell contraction and Hb-jet ejection. Our biomechanical model, which relates the Hb-jet-driven cell motion to the cytosolic pressure generation via elastic contraction of the RBC membrane, showed that the contributions of the bilayer and the bilayer-anchored spectrin cytoskeleton to the hemolytic cell motion are negligible. Consistent with the biomechanical analysis, our biochemical experiments, involving extracellular ATP and the myosin inhibitor blebbistatin, identify the low abundant non-muscle myosin 2A (NM2A) as the key contributor to the Hb-jet emission and fast hemolytic cell motion. Thus, our data reveal a rapid myosin-based mechanism of hemolysis, as opposed to a much slower diffusive Hb efflux.

2021[ to top ]

A role for TASK2 channels in the human immunological synapse Fernández-Orth, Juncal; Rolfes, Leoni; Gola, Lukas; Bittner, Stefan; Andronic, Joseph; Sukhorukov, Vladimir L.; Sisario, Dmitri; Landgraf, Peter; Dieterich, Daniela C.; Cerina, Manuela; Smalla, Karl-Heinz; Kähne, Thilo; Budde, Thomas; Kovac, Stjepana; Ruck, Tobias; Sauer, Markus; Meuth, Sven G. in European Journal of Immunology (2021). 51(2) 342–353.
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Abstract The immunological synapse is a transient junction that occurs when the plasma membrane of a T cell comes in close contact with an APC after recognizing a peptide from the antigen-MHC. The interaction starts when CRAC channels embedded in the T cell membrane open, flowing calcium ions into the cell. To counterbalance the ion influx and subsequent depolarization, Kv1.3 and KCa3.1 channels are recruited to the immunological synapse, increasing the extracellular K+ concentration. These processes are crucial as they initiate gene expression that drives T cell activation and proliferation. The T cell-specific function of the K2P channel family member TASK2 channels and their role in autoimmune processes remains unclear. Using mass spectrometry analysis together with epifluorescence and super-resolution single-molecule localization microscopy, we identified TASK2 channels as novel players recruited to the immunological synapse upon stimulation. TASK2 localizes at the immunological synapse, upon stimulation with CD3 antibodies, likely interacting with these molecules. Our findings suggest that, together with Kv1.3 and KCa3.1 channels, TASK2 channels contribute to the proper functioning of the immunological synapse, and represent an interesting treatment target for T cell-mediated autoimmune disorders.

@article{fernandezorth2021task2, abstract = {Abstract The immunological synapse is a transient junction that occurs when the plasma membrane of a T cell comes in close contact with an APC after recognizing a peptide from the antigen-MHC. The interaction starts when CRAC channels embedded in the T cell membrane open, flowing calcium ions into the cell. To counterbalance the ion influx and subsequent depolarization, Kv1.3 and KCa3.1 channels are recruited to the immunological synapse, increasing the extracellular K+ concentration. These processes are crucial as they initiate gene expression that drives T cell activation and proliferation. The T cell-specific function of the K2P channel family member TASK2 channels and their role in autoimmune processes remains unclear. Using mass spectrometry analysis together with epifluorescence and super-resolution single-molecule localization microscopy, we identified TASK2 channels as novel players recruited to the immunological synapse upon stimulation. TASK2 localizes at the immunological synapse, upon stimulation with CD3 antibodies, likely interacting with these molecules. Our findings suggest that, together with Kv1.3 and KCa3.1 channels, TASK2 channels contribute to the proper functioning of the immunological synapse, and represent an interesting treatment target for T cell-mediated autoimmune disorders.}, author = {Fernández-Orth, Juncal and Rolfes, Leoni and Gola, Lukas and Bittner, Stefan and Andronic, Joseph and Sukhorukov, Vladimir L. and Sisario, Dmitri and Landgraf, Peter and Dieterich, Daniela C. and Cerina, Manuela and Smalla, Karl-Heinz and Kähne, Thilo and Budde, Thomas and Kovac, Stjepana and Ruck, Tobias and Sauer, Markus and Meuth, Sven G.}, booktitle = {European Journal of Immunology}, journal = {European Journal of Immunology}, keywords = {vladimir}, month = {feb}, number = 2, pages = {342–353}, publisher = {John Wiley & Sons, Ltd}, title = {A role for TASK2 channels in the human immunological synapse}, volume = 51, year = 2021 }

%0 Journal Article %1 fernandezorth2021task2 %A Fernández-Orth, Juncal %A Rolfes, Leoni %A Gola, Lukas %A Bittner, Stefan %A Andronic, Joseph %A Sukhorukov, Vladimir L. %A Sisario, Dmitri %A Landgraf, Peter %A Dieterich, Daniela C. %A Cerina, Manuela %A Smalla, Karl-Heinz %A Kähne, Thilo %A Budde, Thomas %A Kovac, Stjepana %A Ruck, Tobias %A Sauer, Markus %A Meuth, Sven G. %B European Journal of Immunology %D 2021 %I John Wiley & Sons, Ltd %J European Journal of Immunology %N 2 %P 342--353 %R https://doi.org/10.1002/eji.201948269 %T A role for TASK2 channels in the human immunological synapse %U https://doi.org/10.1002/eji.201948269 %V 51 %X Abstract The immunological synapse is a transient junction that occurs when the plasma membrane of a T cell comes in close contact with an APC after recognizing a peptide from the antigen-MHC. The interaction starts when CRAC channels embedded in the T cell membrane open, flowing calcium ions into the cell. To counterbalance the ion influx and subsequent depolarization, Kv1.3 and KCa3.1 channels are recruited to the immunological synapse, increasing the extracellular K+ concentration. These processes are crucial as they initiate gene expression that drives T cell activation and proliferation. The T cell-specific function of the K2P channel family member TASK2 channels and their role in autoimmune processes remains unclear. Using mass spectrometry analysis together with epifluorescence and super-resolution single-molecule localization microscopy, we identified TASK2 channels as novel players recruited to the immunological synapse upon stimulation. TASK2 localizes at the immunological synapse, upon stimulation with CD3 antibodies, likely interacting with these molecules. Our findings suggest that, together with Kv1.3 and KCa3.1 channels, TASK2 channels contribute to the proper functioning of the immunological synapse, and represent an interesting treatment target for T cell-mediated autoimmune disorders.
Azidosphinganine enables metabolic labeling and detection of sphingolipid de novo synthesis Fink, Julian; Schumacher, Fabian; Schlegel, Jan; Stenzel, Philipp; Wigger, Dominik; Sauer, Markus; Kleuser, Burkhard; Seibel, Jürgen in Org. Biomol. Chem. (2021). 19(10) 2203–2212.
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Here were report the combination of biocompatible click chemistry of ω-azidosphinganine with fluorescence microscopy and mass spectrometry as a powerful tool to elaborate the sphingolipid metabolism. The azide probe was efficiently synthesized over 13 steps starting from l-serine in an overall yield of 20% and was used for live-cell fluorescence imaging of the endoplasmic reticulum in living cells by bioorthogonal click reaction with a DBCO-labeled fluorophore revealing that the incorporated analogue is mainly localized in the endoplasmic membrane like the endogenous species. A LC-MS(/MS)-based microsomal in vitro assay confirmed that ω-azidosphinganine mimics the natural species enabling the identification and analysis of metabolic breakdown products of sphinganine as a key starting intermediate in the complex sphingolipid biosynthetic pathways. Furthermore, the sphinganine-fluorophore conjugate after click reaction was enzymatically tolerated to form its dihydroceramide and ceramide metabolites. Thus, ω-azidosphinganine represents a useful biofunctional tool for metabolic investigations both by in vivo fluorescence imaging of the sphingolipid subcellular localization in the ER and by in vitro high-resolution mass spectrometry analysis. This should reveal novel insights of the molecular mechanisms sphingolipids and their processing enzymes have e.g. in infection.

@article{fink2021azidosphinganine, abstract = {Here were report the combination of biocompatible click chemistry of ω-azidosphinganine with fluorescence microscopy and mass spectrometry as a powerful tool to elaborate the sphingolipid metabolism. The azide probe was efficiently synthesized over 13 steps starting from l-serine in an overall yield of 20% and was used for live-cell fluorescence imaging of the endoplasmic reticulum in living cells by bioorthogonal click reaction with a DBCO-labeled fluorophore revealing that the incorporated analogue is mainly localized in the endoplasmic membrane like the endogenous species. A LC-MS(/MS)-based microsomal in vitro assay confirmed that ω-azidosphinganine mimics the natural species enabling the identification and analysis of metabolic breakdown products of sphinganine as a key starting intermediate in the complex sphingolipid biosynthetic pathways. Furthermore, the sphinganine-fluorophore conjugate after click reaction was enzymatically tolerated to form its dihydroceramide and ceramide metabolites. Thus, ω-azidosphinganine represents a useful biofunctional tool for metabolic investigations both by in vivo fluorescence imaging of the sphingolipid subcellular localization in the ER and by in vitro high-resolution mass spectrometry analysis. This should reveal novel insights of the molecular mechanisms sphingolipids and their processing enzymes have e.g. in infection.}, author = {Fink, Julian and Schumacher, Fabian and Schlegel, Jan and Stenzel, Philipp and Wigger, Dominik and Sauer, Markus and Kleuser, Burkhard and Seibel, Jürgen}, journal = {Org. Biomol. Chem.}, keywords = {sauer}, number = 10, pages = {2203–2212}, publisher = {The Royal Society of Chemistry}, title = {Azidosphinganine enables metabolic labeling and detection of sphingolipid de novo synthesis}, volume = 19, year = 2021 }

%0 Journal Article %1 fink2021azidosphinganine %A Fink, Julian %A Schumacher, Fabian %A Schlegel, Jan %A Stenzel, Philipp %A Wigger, Dominik %A Sauer, Markus %A Kleuser, Burkhard %A Seibel, Jürgen %D 2021 %I The Royal Society of Chemistry %J Org. Biomol. Chem. %N 10 %P 2203--2212 %R 10.1039/D0OB02592E %T Azidosphinganine enables metabolic labeling and detection of sphingolipid de novo synthesis %U http://dx.doi.org/10.1039/D0OB02592E %V 19 %X Here were report the combination of biocompatible click chemistry of ω-azidosphinganine with fluorescence microscopy and mass spectrometry as a powerful tool to elaborate the sphingolipid metabolism. The azide probe was efficiently synthesized over 13 steps starting from l-serine in an overall yield of 20% and was used for live-cell fluorescence imaging of the endoplasmic reticulum in living cells by bioorthogonal click reaction with a DBCO-labeled fluorophore revealing that the incorporated analogue is mainly localized in the endoplasmic membrane like the endogenous species. A LC-MS(/MS)-based microsomal in vitro assay confirmed that ω-azidosphinganine mimics the natural species enabling the identification and analysis of metabolic breakdown products of sphinganine as a key starting intermediate in the complex sphingolipid biosynthetic pathways. Furthermore, the sphinganine-fluorophore conjugate after click reaction was enzymatically tolerated to form its dihydroceramide and ceramide metabolites. Thus, ω-azidosphinganine represents a useful biofunctional tool for metabolic investigations both by in vivo fluorescence imaging of the sphingolipid subcellular localization in the ER and by in vitro high-resolution mass spectrometry analysis. This should reveal novel insights of the molecular mechanisms sphingolipids and their processing enzymes have e.g. in infection.
Modified Rhodopsins From Aureobasidium pullulans Excel With Very High Proton-Transport Rates Panzer, Sabine; Zhang, Chong; Konte, Tilen; Bräuer, Celine; Diemar, Anne; Yogendran, Parathy; Yu-Strzelczyk, Jing; Nagel, Georg; Gao, Shiqiang; Terpitz, Ulrich in Frontiers in Molecular Biosciences (2021). 8
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Aureobasidium pullulans is a black fungus that can adapt to various stressful conditions like hypersaline, acidic, and alkaline environments. The genome of A. pullulans exhibits three genes coding for putative opsins ApOps1, ApOps2, and ApOps3. We heterologously expressed these genes in mammalian cells and Xenopus oocytes. Localization in the plasma membrane was greatly improved by introducing additional membrane trafficking signals at the N-terminus and the C-terminus. In patch-clamp and two-electrode-voltage clamp experiments, all three proteins showed proton pump activity with maximal activity in green light. Among them, ApOps2 exhibited the most pronounced proton pump activity with current amplitudes occasionally extending 10 pA/pF at 0 mV. Proton pump activity was further supported in the presence of extracellular weak organic acids. Furthermore, we used site-directed mutagenesis to reshape protein functions and thereby implemented light-gated proton channels. We discuss the difference to other well-known proton pumps and the potential of these rhodopsins for optogenetic applications.

@article{panzer2021modified, abstract = {Aureobasidium pullulans is a black fungus that can adapt to various stressful conditions like hypersaline, acidic, and alkaline environments. The genome of A. pullulans exhibits three genes coding for putative opsins ApOps1, ApOps2, and ApOps3. We heterologously expressed these genes in mammalian cells and Xenopus oocytes. Localization in the plasma membrane was greatly improved by introducing additional membrane trafficking signals at the N-terminus and the C-terminus. In patch-clamp and two-electrode-voltage clamp experiments, all three proteins showed proton pump activity with maximal activity in green light. Among them, ApOps2 exhibited the most pronounced proton pump activity with current amplitudes occasionally extending 10 pA/pF at 0 mV. Proton pump activity was further supported in the presence of extracellular weak organic acids. Furthermore, we used site-directed mutagenesis to reshape protein functions and thereby implemented light-gated proton channels. We discuss the difference to other well-known proton pumps and the potential of these rhodopsins for optogenetic applications.}, author = {Panzer, Sabine and Zhang, Chong and Konte, Tilen and Bräuer, Celine and Diemar, Anne and Yogendran, Parathy and Yu-Strzelczyk, Jing and Nagel, Georg and Gao, Shiqiang and Terpitz, Ulrich}, journal = {Frontiers in Molecular Biosciences}, keywords = {terpitz}, series = 941, title = {Modified Rhodopsins From Aureobasidium pullulans Excel With Very High Proton-Transport Rates}, volume = 8, year = 2021 }

%0 Journal Article %1 panzer2021modified %A Panzer, Sabine %A Zhang, Chong %A Konte, Tilen %A Bräuer, Celine %A Diemar, Anne %A Yogendran, Parathy %A Yu-Strzelczyk, Jing %A Nagel, Georg %A Gao, Shiqiang %A Terpitz, Ulrich %B 941 %D 2021 %J Frontiers in Molecular Biosciences %T Modified Rhodopsins From Aureobasidium pullulans Excel With Very High Proton-Transport Rates %U https://www.frontiersin.org/article/10.3389/fmolb.2021.750528 %V 8 %X Aureobasidium pullulans is a black fungus that can adapt to various stressful conditions like hypersaline, acidic, and alkaline environments. The genome of A. pullulans exhibits three genes coding for putative opsins ApOps1, ApOps2, and ApOps3. We heterologously expressed these genes in mammalian cells and Xenopus oocytes. Localization in the plasma membrane was greatly improved by introducing additional membrane trafficking signals at the N-terminus and the C-terminus. In patch-clamp and two-electrode-voltage clamp experiments, all three proteins showed proton pump activity with maximal activity in green light. Among them, ApOps2 exhibited the most pronounced proton pump activity with current amplitudes occasionally extending 10 pA/pF at 0 mV. Proton pump activity was further supported in the presence of extracellular weak organic acids. Furthermore, we used site-directed mutagenesis to reshape protein functions and thereby implemented light-gated proton channels. We discuss the difference to other well-known proton pumps and the potential of these rhodopsins for optogenetic applications.
Click-correlative light and electron microscopy (click-AT-CLEM) for imaging and tracking azido-functionalized sphingolipids in bacteria Peters, Simon; Kaiser, Lena; Fink, Julian; Schumacher, Fabian; Perschin, Veronika; Schlegel, Jan; Sauer, Markus; Stigloher, Christian; Kleuser, Burkhard; Seibel, Jürgen; Schubert-Unkmeir, Alexandra in Scientific Reports (2021). 11(1) 4300-.
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Sphingolipids, including ceramides, are a diverse group of structurally related lipids composed of a sphingoid base backbone coupled to a fatty acid side chain and modified terminal hydroxyl group. Recently, it has been shown that sphingolipids show antimicrobial activity against a broad range of pathogenic microorganisms. The antimicrobial mechanism, however, remains so far elusive. Here, we introduce ‘click-AT-CLEM’, a labeling technique for correlated light and electron microscopy (CLEM) based on the super-resolution array tomography (srAT) approach and bio-orthogonal click chemistry for imaging of azido-tagged sphingolipids to directly visualize their interaction with the model Gram-negative bacterium Neisseria meningitidis at subcellular level. We observed ultrastructural damage of bacteria and disruption of the bacterial outer membrane induced by two azido-modified sphingolipids by scanning electron microscopy and transmission electron microscopy. Click-AT-CLEM imaging and mass spectrometry clearly revealed efficient incorporation of azido-tagged sphingolipids into the outer membrane of Gram-negative bacteria as underlying cause of their antimicrobial activity.

@article{peters2021clickcorrelative, abstract = {Sphingolipids, including ceramides, are a diverse group of structurally related lipids composed of a sphingoid base backbone coupled to a fatty acid side chain and modified terminal hydroxyl group. Recently, it has been shown that sphingolipids show antimicrobial activity against a broad range of pathogenic microorganisms. The antimicrobial mechanism, however, remains so far elusive. Here, we introduce ‘click-AT-CLEM’, a labeling technique for correlated light and electron microscopy (CLEM) based on the super-resolution array tomography (srAT) approach and bio-orthogonal click chemistry for imaging of azido-tagged sphingolipids to directly visualize their interaction with the model Gram-negative bacterium Neisseria meningitidis at subcellular level. We observed ultrastructural damage of bacteria and disruption of the bacterial outer membrane induced by two azido-modified sphingolipids by scanning electron microscopy and transmission electron microscopy. Click-AT-CLEM imaging and mass spectrometry clearly revealed efficient incorporation of azido-tagged sphingolipids into the outer membrane of Gram-negative bacteria as underlying cause of their antimicrobial activity.}, author = {Peters, Simon and Kaiser, Lena and Fink, Julian and Schumacher, Fabian and Perschin, Veronika and Schlegel, Jan and Sauer, Markus and Stigloher, Christian and Kleuser, Burkhard and Seibel, Jürgen and Schubert-Unkmeir, Alexandra}, journal = {Scientific Reports}, keywords = {sauer}, number = 1, pages = {4300–}, title = {Click-correlative light and electron microscopy (click-AT-CLEM) for imaging and tracking azido-functionalized sphingolipids in bacteria}, volume = 11, year = 2021 }

%0 Journal Article %1 peters2021clickcorrelative %A Peters, Simon %A Kaiser, Lena %A Fink, Julian %A Schumacher, Fabian %A Perschin, Veronika %A Schlegel, Jan %A Sauer, Markus %A Stigloher, Christian %A Kleuser, Burkhard %A Seibel, Jürgen %A Schubert-Unkmeir, Alexandra %D 2021 %J Scientific Reports %N 1 %P 4300-- %R 10.1038/s41598-021-83813-w %T Click-correlative light and electron microscopy (click-AT-CLEM) for imaging and tracking azido-functionalized sphingolipids in bacteria %U https://doi.org/10.1038/s41598-021-83813-w %V 11 %X Sphingolipids, including ceramides, are a diverse group of structurally related lipids composed of a sphingoid base backbone coupled to a fatty acid side chain and modified terminal hydroxyl group. Recently, it has been shown that sphingolipids show antimicrobial activity against a broad range of pathogenic microorganisms. The antimicrobial mechanism, however, remains so far elusive. Here, we introduce ‘click-AT-CLEM’, a labeling technique for correlated light and electron microscopy (CLEM) based on the super-resolution array tomography (srAT) approach and bio-orthogonal click chemistry for imaging of azido-tagged sphingolipids to directly visualize their interaction with the model Gram-negative bacterium Neisseria meningitidis at subcellular level. We observed ultrastructural damage of bacteria and disruption of the bacterial outer membrane induced by two azido-modified sphingolipids by scanning electron microscopy and transmission electron microscopy. Click-AT-CLEM imaging and mass spectrometry clearly revealed efficient incorporation of azido-tagged sphingolipids into the outer membrane of Gram-negative bacteria as underlying cause of their antimicrobial activity.
Subdiffraction-resolution fluorescence imaging of immunological synapse formation between NK cells and A. fumigatus by expansion microscopy Trinks, Nora; Reinhard, Sebastian; Drobny, Matthias; Heilig, Linda; Löffler, Jürgen; Sauer, Markus; Terpitz, Ulrich in Communications Biology (2021). 4(1) 1151-.
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Expansion microscopy (ExM) enables super-resolution fluorescence imaging on standard microscopes by physical expansion of the sample. However, the investigation of interactions between different organisms such as mammalian and fungal cells by ExM remains challenging because different cell types require different expansion protocols to ensure identical, ideally isotropic expansion of both partners. Here, we introduce an ExM method that enables super-resolved visualization of the interaction between NK cells and Aspergillus fumigatus hyphae. 4-fold expansion in combination with confocal fluorescence imaging allows us to resolve details of cytoskeleton rearrangement as well as NK cells’ lytic granules triggered by contact with an RFP-expressing A. fumigatus strain. In particular, subdiffraction-resolution images show polarized degranulation upon contact formation and the presence of LAMP1 surrounding perforin at the NK cell-surface post degranulation. Our data demonstrate that optimized ExM protocols enable the investigation of immunological synapse formation between two different species with so far unmatched spatial resolution.

@article{trinks2021subdiffractionresolution, abstract = {Expansion microscopy (ExM) enables super-resolution fluorescence imaging on standard microscopes by physical expansion of the sample. However, the investigation of interactions between different organisms such as mammalian and fungal cells by ExM remains challenging because different cell types require different expansion protocols to ensure identical, ideally isotropic expansion of both partners. Here, we introduce an ExM method that enables super-resolved visualization of the interaction between NK cells and Aspergillus fumigatus hyphae. 4-fold expansion in combination with confocal fluorescence imaging allows us to resolve details of cytoskeleton rearrangement as well as NK cells’ lytic granules triggered by contact with an RFP-expressing A. fumigatus strain. In particular, subdiffraction-resolution images show polarized degranulation upon contact formation and the presence of LAMP1 surrounding perforin at the NK cell-surface post degranulation. Our data demonstrate that optimized ExM protocols enable the investigation of immunological synapse formation between two different species with so far unmatched spatial resolution.}, author = {Trinks, Nora and Reinhard, Sebastian and Drobny, Matthias and Heilig, Linda and Löffler, Jürgen and Sauer, Markus and Terpitz, Ulrich}, journal = {Communications Biology}, keywords = {terpitz}, number = 1, pages = {1151–}, title = {Subdiffraction-resolution fluorescence imaging of immunological synapse formation between NK cells and A. fumigatus by expansion microscopy}, volume = 4, year = 2021 }

%0 Journal Article %1 trinks2021subdiffractionresolution %A Trinks, Nora %A Reinhard, Sebastian %A Drobny, Matthias %A Heilig, Linda %A Löffler, Jürgen %A Sauer, Markus %A Terpitz, Ulrich %D 2021 %J Communications Biology %N 1 %P 1151-- %R 10.1038/s42003-021-02669-y %T Subdiffraction-resolution fluorescence imaging of immunological synapse formation between NK cells and A. fumigatus by expansion microscopy %U https://doi.org/10.1038/s42003-021-02669-y %V 4 %X Expansion microscopy (ExM) enables super-resolution fluorescence imaging on standard microscopes by physical expansion of the sample. However, the investigation of interactions between different organisms such as mammalian and fungal cells by ExM remains challenging because different cell types require different expansion protocols to ensure identical, ideally isotropic expansion of both partners. Here, we introduce an ExM method that enables super-resolved visualization of the interaction between NK cells and Aspergillus fumigatus hyphae. 4-fold expansion in combination with confocal fluorescence imaging allows us to resolve details of cytoskeleton rearrangement as well as NK cells’ lytic granules triggered by contact with an RFP-expressing A. fumigatus strain. In particular, subdiffraction-resolution images show polarized degranulation upon contact formation and the presence of LAMP1 surrounding perforin at the NK cell-surface post degranulation. Our data demonstrate that optimized ExM protocols enable the investigation of immunological synapse formation between two different species with so far unmatched spatial resolution.
Opposite effects of the triple target (DNA-PK/PI3K/mTOR) inhibitor PI-103 on the radiation sensitivity of glioblastoma cell lines proficient and deficient in DNA-PKcs Djuzenova, Cholpon S.; Fischer, Thomas; Katzer, Astrid; Sisario, Dmitri; Korsa, Tessa; Steussloff, Gudrun; Sukhorukov, Vladimir L.; Flentje, Michael in BMC Cancer (2021). 21(1) 1201-.
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Radiotherapy is routinely used to combat glioblastoma (GBM). However, the treatment efficacy is often limited by the radioresistance of GBM cells.

@article{djuzenova2021opposite, abstract = {Radiotherapy is routinely used to combat glioblastoma (GBM). However, the treatment efficacy is often limited by the radioresistance of GBM cells.}, author = {Djuzenova, Cholpon S. and Fischer, Thomas and Katzer, Astrid and Sisario, Dmitri and Korsa, Tessa and Steussloff, Gudrun and Sukhorukov, Vladimir L. and Flentje, Michael}, journal = {BMC Cancer}, keywords = {vladimir}, number = 1, pages = {1201–}, title = {Opposite effects of the triple target (DNA-PK/PI3K/mTOR) inhibitor PI-103 on the radiation sensitivity of glioblastoma cell lines proficient and deficient in DNA-PKcs}, volume = 21, year = 2021 }

%0 Journal Article %1 djuzenova2021opposite %A Djuzenova, Cholpon S. %A Fischer, Thomas %A Katzer, Astrid %A Sisario, Dmitri %A Korsa, Tessa %A Steussloff, Gudrun %A Sukhorukov, Vladimir L. %A Flentje, Michael %D 2021 %J BMC Cancer %N 1 %P 1201-- %R 10.1186/s12885-021-08930-1 %T Opposite effects of the triple target (DNA-PK/PI3K/mTOR) inhibitor PI-103 on the radiation sensitivity of glioblastoma cell lines proficient and deficient in DNA-PKcs %U https://doi.org/10.1186/s12885-021-08930-1 %V 21 %X Radiotherapy is routinely used to combat glioblastoma (GBM). However, the treatment efficacy is often limited by the radioresistance of GBM cells.
Two-colour single-molecule photoinduced electron transfer fluorescence imaging microscopy of chaperone dynamics Schubert, Jonathan; Schulze, Andrea; Prodromou, Chrisostomos; Neuweiler, Hannes in Nature Communications (2021). 12(1) 6964-.
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Many proteins are molecular machines, whose function is dependent on multiple conformational changes that are initiated and tightly controlled through biochemical stimuli. Their mechanistic understanding calls for spectroscopy that can probe simultaneously such structural coordinates. Here we present two-colour fluorescence microscopy in combination with photoinduced electron transfer (PET) probes as a method that simultaneously detects two structural coordinates in single protein molecules, one colour per coordinate. This contrasts with the commonly applied resonance energy transfer (FRET) technique that requires two colours per coordinate. We demonstrate the technique by directly and simultaneously observing three critical structural changes within the Hsp90 molecular chaperone machinery. Our results reveal synchronicity of conformational motions at remote sites during ATPase-driven closure of the Hsp90 molecular clamp, providing evidence for a cooperativity mechanism in the chaperone’s catalytic cycle. Single-molecule PET fluorescence microscopy opens up avenues in the multi-dimensional exploration of protein dynamics and allosteric mechanisms.

@article{schubert2021twocolour, abstract = {Many proteins are molecular machines, whose function is dependent on multiple conformational changes that are initiated and tightly controlled through biochemical stimuli. Their mechanistic understanding calls for spectroscopy that can probe simultaneously such structural coordinates. Here we present two-colour fluorescence microscopy in combination with photoinduced electron transfer (PET) probes as a method that simultaneously detects two structural coordinates in single protein molecules, one colour per coordinate. This contrasts with the commonly applied resonance energy transfer (FRET) technique that requires two colours per coordinate. We demonstrate the technique by directly and simultaneously observing three critical structural changes within the Hsp90 molecular chaperone machinery. Our results reveal synchronicity of conformational motions at remote sites during ATPase-driven closure of the Hsp90 molecular clamp, providing evidence for a cooperativity mechanism in the chaperone’s catalytic cycle. Single-molecule PET fluorescence microscopy opens up avenues in the multi-dimensional exploration of protein dynamics and allosteric mechanisms.}, author = {Schubert, Jonathan and Schulze, Andrea and Prodromou, Chrisostomos and Neuweiler, Hannes}, journal = {Nature Communications}, keywords = {hannes}, number = 1, pages = {6964–}, title = {Two-colour single-molecule photoinduced electron transfer fluorescence imaging microscopy of chaperone dynamics}, volume = 12, year = 2021 }

%0 Journal Article %1 schubert2021twocolour %A Schubert, Jonathan %A Schulze, Andrea %A Prodromou, Chrisostomos %A Neuweiler, Hannes %D 2021 %J Nature Communications %N 1 %P 6964-- %R 10.1038/s41467-021-27286-5 %T Two-colour single-molecule photoinduced electron transfer fluorescence imaging microscopy of chaperone dynamics %U https://doi.org/10.1038/s41467-021-27286-5 %V 12 %X Many proteins are molecular machines, whose function is dependent on multiple conformational changes that are initiated and tightly controlled through biochemical stimuli. Their mechanistic understanding calls for spectroscopy that can probe simultaneously such structural coordinates. Here we present two-colour fluorescence microscopy in combination with photoinduced electron transfer (PET) probes as a method that simultaneously detects two structural coordinates in single protein molecules, one colour per coordinate. This contrasts with the commonly applied resonance energy transfer (FRET) technique that requires two colours per coordinate. We demonstrate the technique by directly and simultaneously observing three critical structural changes within the Hsp90 molecular chaperone machinery. Our results reveal synchronicity of conformational motions at remote sites during ATPase-driven closure of the Hsp90 molecular clamp, providing evidence for a cooperativity mechanism in the chaperone’s catalytic cycle. Single-molecule PET fluorescence microscopy opens up avenues in the multi-dimensional exploration of protein dynamics and allosteric mechanisms.
Warhead Reactivity Limits the Speed of Inhibition of the Cysteine Protease Rhodesain Johe, Patrick; Jung, Sascha; Endres, Erik; Kersten, Christian; Zimmer, Collin; Ye, Weixiang; Sönnichsen, Carsten; Hellmich, Ute A.; Sotriffer, Christoph; Schirmeister, Tanja; Neuweiler, Hannes in ACS Chem. Biol. (2021). 16(4) 661–670.
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Viral and parasitic pathogens rely critically on cysteine proteases for host invasion, replication, and infectivity. Their inhibition by synthetic inhibitors, such as vinyl sulfone compounds, has emerged as a promising treatment strategy. However, the individual reaction steps of protease inhibition are not fully understood. Using the trypanosomal cysteine protease rhodesain as a medically relevant target, we design photoinduced electron transfer (PET) fluorescence probes to detect kinetics of binding of reversible and irreversible vinyl sulfones directly in solution. Intriguingly, the irreversible inhibitor, apart from its unlimited residence time in the enzyme, reacts 5 times faster than the reversible one. Results show that the reactivity of the warhead, and not binding of the peptidic recognition unit, limits the rate constant of protease inhibition. The use of a reversible inhibitor decreases the risk of off-target side effects not only by allowing its release from an off-target but also by reducing the rate constant of binding.

@article{johe2021warhead, abstract = {Viral and parasitic pathogens rely critically on cysteine proteases for host invasion, replication, and infectivity. Their inhibition by synthetic inhibitors, such as vinyl sulfone compounds, has emerged as a promising treatment strategy. However, the individual reaction steps of protease inhibition are not fully understood. Using the trypanosomal cysteine protease rhodesain as a medically relevant target, we design photoinduced electron transfer (PET) fluorescence probes to detect kinetics of binding of reversible and irreversible vinyl sulfones directly in solution. Intriguingly, the irreversible inhibitor, apart from its unlimited residence time in the enzyme, reacts 5 times faster than the reversible one. Results show that the reactivity of the warhead, and not binding of the peptidic recognition unit, limits the rate constant of protease inhibition. The use of a reversible inhibitor decreases the risk of off-target side effects not only by allowing its release from an off-target but also by reducing the rate constant of binding.}, author = {Johe, Patrick and Jung, Sascha and Endres, Erik and Kersten, Christian and Zimmer, Collin and Ye, Weixiang and Sönnichsen, Carsten and Hellmich, Ute A. and Sotriffer, Christoph and Schirmeister, Tanja and Neuweiler, Hannes}, booktitle = {ACS Chemical Biology}, journal = {ACS Chem. Biol.}, keywords = {hannes}, month = {apr}, number = 4, pages = {661–670}, publisher = {American Chemical Society}, title = {Warhead Reactivity Limits the Speed of Inhibition of the Cysteine Protease Rhodesain}, volume = 16, year = 2021 }

%0 Journal Article %1 johe2021warhead %A Johe, Patrick %A Jung, Sascha %A Endres, Erik %A Kersten, Christian %A Zimmer, Collin %A Ye, Weixiang %A Sönnichsen, Carsten %A Hellmich, Ute A. %A Sotriffer, Christoph %A Schirmeister, Tanja %A Neuweiler, Hannes %B ACS Chemical Biology %D 2021 %I American Chemical Society %J ACS Chem. Biol. %N 4 %P 661--670 %R 10.1021/acschembio.0c00911 %T Warhead Reactivity Limits the Speed of Inhibition of the Cysteine Protease Rhodesain %U https://doi.org/10.1021/acschembio.0c00911 %V 16 %X Viral and parasitic pathogens rely critically on cysteine proteases for host invasion, replication, and infectivity. Their inhibition by synthetic inhibitors, such as vinyl sulfone compounds, has emerged as a promising treatment strategy. However, the individual reaction steps of protease inhibition are not fully understood. Using the trypanosomal cysteine protease rhodesain as a medically relevant target, we design photoinduced electron transfer (PET) fluorescence probes to detect kinetics of binding of reversible and irreversible vinyl sulfones directly in solution. Intriguingly, the irreversible inhibitor, apart from its unlimited residence time in the enzyme, reacts 5 times faster than the reversible one. Results show that the reactivity of the warhead, and not binding of the peptidic recognition unit, limits the rate constant of protease inhibition. The use of a reversible inhibitor decreases the risk of off-target side effects not only by allowing its release from an off-target but also by reducing the rate constant of binding.
Structure, interdomain dynamics, and pH-dependent autoactivation of pro-rhodesain, the main lysosomal cysteine protease from African trypanosomes Johé, Patrick; Jaenicke, Elmar; Neuweiler, Hannes; Schirmeister, Tanja; Kersten, Christian; Hellmich, Ute A. in Journal of Biological Chemistry (2021). 296 100565-.
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Rhodesain is the lysosomal cathepsin L-like cysteine protease of Trypanosoma brucei rhodesiense, the causative agent of Human African Trypanosomiasis. The enzyme is essential for the proliferation and pathogenicity of the parasite as well as its ability to overcome the blood–brain barrier of the host. Lysosomal cathepsins are expressed as zymogens with an inactivating prodomain that is cleaved under acidic conditions. A structure of the uncleaved maturation intermediate from a trypanosomal cathepsin L-like protease is currently not available. We thus established the heterologous expression of T. brucei rhodesiense pro-rhodesain in Escherichia coli and determined its crystal structure. The trypanosomal prodomain differs from nonparasitic pro-cathepsins by a unique, extended α-helix that blocks the active site and whose side-chain interactions resemble those of the antiprotozoal inhibitor K11777. Interdomain dynamics between pro- and core protease domain as observed by photoinduced electron transfer fluorescence correlation spectroscopy increase at low pH, where pro-rhodesain also undergoes autocleavage. Using the crystal structure, molecular dynamics simulations, and mutagenesis, we identify a conserved interdomain salt bridge that prevents premature intramolecular cleavage at higher pH values and may thus present a control switch for the observed pH sensitivity of proenzyme cleavage in (trypanosomal) CathL-like proteases.

@article{johe2021structure, abstract = {Rhodesain is the lysosomal cathepsin L-like cysteine protease of Trypanosoma brucei rhodesiense, the causative agent of Human African Trypanosomiasis. The enzyme is essential for the proliferation and pathogenicity of the parasite as well as its ability to overcome the blood–brain barrier of the host. Lysosomal cathepsins are expressed as zymogens with an inactivating prodomain that is cleaved under acidic conditions. A structure of the uncleaved maturation intermediate from a trypanosomal cathepsin L-like protease is currently not available. We thus established the heterologous expression of T. brucei rhodesiense pro-rhodesain in Escherichia coli and determined its crystal structure. The trypanosomal prodomain differs from nonparasitic pro-cathepsins by a unique, extended α-helix that blocks the active site and whose side-chain interactions resemble those of the antiprotozoal inhibitor K11777. Interdomain dynamics between pro- and core protease domain as observed by photoinduced electron transfer fluorescence correlation spectroscopy increase at low pH, where pro-rhodesain also undergoes autocleavage. Using the crystal structure, molecular dynamics simulations, and mutagenesis, we identify a conserved interdomain salt bridge that prevents premature intramolecular cleavage at higher pH values and may thus present a control switch for the observed pH sensitivity of proenzyme cleavage in (trypanosomal) CathL-like proteases.}, author = {Johé, Patrick and Jaenicke, Elmar and Neuweiler, Hannes and Schirmeister, Tanja and Kersten, Christian and Hellmich, Ute A.}, journal = {Journal of Biological Chemistry}, keywords = {hannes}, pages = {100565–}, title = {Structure, interdomain dynamics, and pH-dependent autoactivation of pro-rhodesain, the main lysosomal cysteine protease from African trypanosomes}, volume = 296, year = 2021 }

%0 Journal Article %1 johe2021structure %A Johé, Patrick %A Jaenicke, Elmar %A Neuweiler, Hannes %A Schirmeister, Tanja %A Kersten, Christian %A Hellmich, Ute A. %D 2021 %J Journal of Biological Chemistry %P 100565-- %R https://doi.org/10.1016/j.jbc.2021.100565 %T Structure, interdomain dynamics, and pH-dependent autoactivation of pro-rhodesain, the main lysosomal cysteine protease from African trypanosomes %U https://www.sciencedirect.com/science/article/pii/S0021925821003434 %V 296 %X Rhodesain is the lysosomal cathepsin L-like cysteine protease of Trypanosoma brucei rhodesiense, the causative agent of Human African Trypanosomiasis. The enzyme is essential for the proliferation and pathogenicity of the parasite as well as its ability to overcome the blood–brain barrier of the host. Lysosomal cathepsins are expressed as zymogens with an inactivating prodomain that is cleaved under acidic conditions. A structure of the uncleaved maturation intermediate from a trypanosomal cathepsin L-like protease is currently not available. We thus established the heterologous expression of T. brucei rhodesiense pro-rhodesain in Escherichia coli and determined its crystal structure. The trypanosomal prodomain differs from nonparasitic pro-cathepsins by a unique, extended α-helix that blocks the active site and whose side-chain interactions resemble those of the antiprotozoal inhibitor K11777. Interdomain dynamics between pro- and core protease domain as observed by photoinduced electron transfer fluorescence correlation spectroscopy increase at low pH, where pro-rhodesain also undergoes autocleavage. Using the crystal structure, molecular dynamics simulations, and mutagenesis, we identify a conserved interdomain salt bridge that prevents premature intramolecular cleavage at higher pH values and may thus present a control switch for the observed pH sensitivity of proenzyme cleavage in (trypanosomal) CathL-like proteases.
Coregulation of gene expression by White collar 1 and phytochrome in Ustilago maydis Brych, Annika; Haas, Fabian B.; Parzefall, Katharina; Panzer, Sabine; Schermuly, Jeanette; Altmüller, Janine; Engelsdorf, Timo; Terpitz, Ulrich; Rensing, Stefan A.; Kiontke, Stephan; Batschauer, Alfred in Fungal Genetics and Biology (2021). 103570-.
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Ustilago maydis encodes ten predicted light-sensing proteins. The biological functions of only a few of them are elucidated. Among the characterized ones are two DNA-photolyases and two rhodopsins that act as DNA-repair enzymes or green light-driven proton pumps, respectively. Here we report on the role of two other photoreceptors in U. maydis, namely White collar 1 (Wco1) and Phytochrome 1 (Phy1). We show that they bind flavins or biliverdin as chromophores, respectively. Both photoreceptors undergo a photocycle in vitro. Wco1 is the dominant blue light receptor in the saprophytic phase, controlling all of the 324 differentially expressed genes in blue light. U. maydis also responds to red and far-red light. However, the number of red or far-red light-controlled genes is less compared to blue light-regulated ones. Moreover, most of the red and far-red light-controlled genes not only depend on Phy1 but also on Wco1, indicating partial coregulation of gene expression by both photoreceptors. GFP-fused Wco1 is preferentially located in the nucleus, Phy1 in the cytosol, thus providing no hint that these photoreceptors directly interact or operate within the same complex. This is the first report on a functional characterization and coaction of White collar 1 and phytochrome orthologs in basidiomycetes.

@article{brych2021coregulation, abstract = {Ustilago maydis encodes ten predicted light-sensing proteins. The biological functions of only a few of them are elucidated. Among the characterized ones are two DNA-photolyases and two rhodopsins that act as DNA-repair enzymes or green light-driven proton pumps, respectively. Here we report on the role of two other photoreceptors in U. maydis, namely White collar 1 (Wco1) and Phytochrome 1 (Phy1). We show that they bind flavins or biliverdin as chromophores, respectively. Both photoreceptors undergo a photocycle in vitro. Wco1 is the dominant blue light receptor in the saprophytic phase, controlling all of the 324 differentially expressed genes in blue light. U. maydis also responds to red and far-red light. However, the number of red or far-red light-controlled genes is less compared to blue light-regulated ones. Moreover, most of the red and far-red light-controlled genes not only depend on Phy1 but also on Wco1, indicating partial coregulation of gene expression by both photoreceptors. GFP-fused Wco1 is preferentially located in the nucleus, Phy1 in the cytosol, thus providing no hint that these photoreceptors directly interact or operate within the same complex. This is the first report on a functional characterization and coaction of White collar 1 and phytochrome orthologs in basidiomycetes.}, author = {Brych, Annika and Haas, Fabian B. and Parzefall, Katharina and Panzer, Sabine and Schermuly, Jeanette and Altmüller, Janine and Engelsdorf, Timo and Terpitz, Ulrich and Rensing, Stefan A. and Kiontke, Stephan and Batschauer, Alfred}, journal = {Fungal Genetics and Biology}, keywords = {terpitz}, pages = {103570–}, title = {Coregulation of gene expression by White collar 1 and phytochrome in Ustilago maydis}, year = 2021 }

%0 Journal Article %1 brych2021coregulation %A Brych, Annika %A Haas, Fabian B. %A Parzefall, Katharina %A Panzer, Sabine %A Schermuly, Jeanette %A Altmüller, Janine %A Engelsdorf, Timo %A Terpitz, Ulrich %A Rensing, Stefan A. %A Kiontke, Stephan %A Batschauer, Alfred %D 2021 %J Fungal Genetics and Biology %P 103570-- %R https://doi.org/10.1016/j.fgb.2021.103570 %T Coregulation of gene expression by White collar 1 and phytochrome in Ustilago maydis %U https://www.sciencedirect.com/science/article/pii/S1087184521000542 %X Ustilago maydis encodes ten predicted light-sensing proteins. The biological functions of only a few of them are elucidated. Among the characterized ones are two DNA-photolyases and two rhodopsins that act as DNA-repair enzymes or green light-driven proton pumps, respectively. Here we report on the role of two other photoreceptors in U. maydis, namely White collar 1 (Wco1) and Phytochrome 1 (Phy1). We show that they bind flavins or biliverdin as chromophores, respectively. Both photoreceptors undergo a photocycle in vitro. Wco1 is the dominant blue light receptor in the saprophytic phase, controlling all of the 324 differentially expressed genes in blue light. U. maydis also responds to red and far-red light. However, the number of red or far-red light-controlled genes is less compared to blue light-regulated ones. Moreover, most of the red and far-red light-controlled genes not only depend on Phy1 but also on Wco1, indicating partial coregulation of gene expression by both photoreceptors. GFP-fused Wco1 is preferentially located in the nucleus, Phy1 in the cytosol, thus providing no hint that these photoreceptors directly interact or operate within the same complex. This is the first report on a functional characterization and coaction of White collar 1 and phytochrome orthologs in basidiomycetes.
Direct Visualization of Fungal Burden in Filamentous Fungus-Infected Silkworms Yu, Yidong; Wolf, Ann-Katrin; Thusek, Sina; Heinekamp, Thorsten; Bromley, Michael; Krappmann, Sven; Terpitz, Ulrich; Voigt, Kerstin; Brakhage, Axel A.; Beilhack, Andreas (2021).
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Invasive fungal infections (IFIs) are difficult to diagnose and to treat and, despite several available antifungal drugs, cause high mortality rates. In the past decades, the incidence of IFIs has continuously increased. More recently, SARS-CoV-2-associated lethal IFIs have been reported worldwide in critically ill patients. Combating IFIs requires a more profound understanding of fungal pathogenicity to facilitate the development of novel antifungal strategies. Animal models are indispensable for studying fungal infections and to develop new antifungals. However, using mammalian animal models faces various hurdles including ethical issues and high costs, which makes large-scale infection experiments extremely challenging. To overcome these limitations, we optimized an invertebrate model and introduced a simple calcofluor white (CW) staining protocol to macroscopically and microscopically monitor disease progression in silkworms (Bombyx mori) infected with the human pathogenic filamentous fungi Aspergillus fumigatus and Lichtheimia corymbifera. This advanced silkworm A. fumigatus infection model could validate knockout mutants with either attenuated, strongly attenuated or unchanged virulence. Finally, CW staining allowed us to efficiently visualize antifungal treatment outcomes in infected silkworms. Conclusively, we here present a powerful animal model combined with a straightforward staining protocol to expedite large-scale in vivo research of fungal pathogenicity and to investigate novel antifungal candidates.

@misc{yu2021direct, abstract = {Invasive fungal infections (IFIs) are difficult to diagnose and to treat and, despite several available antifungal drugs, cause high mortality rates. In the past decades, the incidence of IFIs has continuously increased. More recently, SARS-CoV-2-associated lethal IFIs have been reported worldwide in critically ill patients. Combating IFIs requires a more profound understanding of fungal pathogenicity to facilitate the development of novel antifungal strategies. Animal models are indispensable for studying fungal infections and to develop new antifungals. However, using mammalian animal models faces various hurdles including ethical issues and high costs, which makes large-scale infection experiments extremely challenging. To overcome these limitations, we optimized an invertebrate model and introduced a simple calcofluor white (CW) staining protocol to macroscopically and microscopically monitor disease progression in silkworms (Bombyx mori) infected with the human pathogenic filamentous fungi Aspergillus fumigatus and Lichtheimia corymbifera. This advanced silkworm A. fumigatus infection model could validate knockout mutants with either attenuated, strongly attenuated or unchanged virulence. Finally, CW staining allowed us to efficiently visualize antifungal treatment outcomes in infected silkworms. Conclusively, we here present a powerful animal model combined with a straightforward staining protocol to expedite large-scale in vivo research of fungal pathogenicity and to investigate novel antifungal candidates.}, author = {Yu, Yidong and Wolf, Ann-Katrin and Thusek, Sina and Heinekamp, Thorsten and Bromley, Michael and Krappmann, Sven and Terpitz, Ulrich and Voigt, Kerstin and Brakhage, Axel A. and Beilhack, Andreas}, booktitle = {Journal of Fungi}, keywords = {terpitz}, number = 2, title = {Direct Visualization of Fungal Burden in Filamentous Fungus-Infected Silkworms}, volume = 7, year = 2021 }

%0 Generic %1 yu2021direct %A Yu, Yidong %A Wolf, Ann-Katrin %A Thusek, Sina %A Heinekamp, Thorsten %A Bromley, Michael %A Krappmann, Sven %A Terpitz, Ulrich %A Voigt, Kerstin %A Brakhage, Axel A. %A Beilhack, Andreas %B Journal of Fungi %D 2021 %N 2 %R 10.3390/jof7020136 %T Direct Visualization of Fungal Burden in Filamentous Fungus-Infected Silkworms %V 7 %X Invasive fungal infections (IFIs) are difficult to diagnose and to treat and, despite several available antifungal drugs, cause high mortality rates. In the past decades, the incidence of IFIs has continuously increased. More recently, SARS-CoV-2-associated lethal IFIs have been reported worldwide in critically ill patients. Combating IFIs requires a more profound understanding of fungal pathogenicity to facilitate the development of novel antifungal strategies. Animal models are indispensable for studying fungal infections and to develop new antifungals. However, using mammalian animal models faces various hurdles including ethical issues and high costs, which makes large-scale infection experiments extremely challenging. To overcome these limitations, we optimized an invertebrate model and introduced a simple calcofluor white (CW) staining protocol to macroscopically and microscopically monitor disease progression in silkworms (Bombyx mori) infected with the human pathogenic filamentous fungi Aspergillus fumigatus and Lichtheimia corymbifera. This advanced silkworm A. fumigatus infection model could validate knockout mutants with either attenuated, strongly attenuated or unchanged virulence. Finally, CW staining allowed us to efficiently visualize antifungal treatment outcomes in infected silkworms. Conclusively, we here present a powerful animal model combined with a straightforward staining protocol to expedite large-scale in vivo research of fungal pathogenicity and to investigate novel antifungal candidates.
Allosteric coupling of sub-millisecond clamshell motions in ionotropic glutamate receptor ligand-binding domains Rajab, Suhaila; Bismin, Leah; Schwarze, Simone; Pinggera, Alexandra; Greger, Ingo H.; Neuweiler, Hannes in Communications Biology (2021). 4(1) 1056-.
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Ionotropic glutamate receptors (iGluRs) mediate signal transmission in the brain and are important drug targets. Structural studies show snapshots of iGluRs, which provide a mechanistic understanding of gating, yet the rapid motions driving the receptor machinery are largely elusive. Here we detect kinetics of conformational change of isolated clamshell-shaped ligand-binding domains (LBDs) from the three major iGluR sub-types, which initiate gating upon binding of agonists. We design fluorescence probes to measure domain motions through nanosecond fluorescence correlation spectroscopy. We observe a broad kinetic spectrum of LBD dynamics that underlie activation of iGluRs. Microsecond clamshell motions slow upon dimerization and freeze upon binding of full and partial agonists. We uncover allosteric coupling within NMDA LBD hetero-dimers, where binding of L-glutamate to the GluN2A LBD stalls clamshell motions of the glycine-binding GluN1 LBD. Our results reveal rapid LBD dynamics across iGluRs and suggest a mechanism of negative allosteric cooperativity in NMDA receptors.

@article{rajab2021allosteric, abstract = {Ionotropic glutamate receptors (iGluRs) mediate signal transmission in the brain and are important drug targets. Structural studies show snapshots of iGluRs, which provide a mechanistic understanding of gating, yet the rapid motions driving the receptor machinery are largely elusive. Here we detect kinetics of conformational change of isolated clamshell-shaped ligand-binding domains (LBDs) from the three major iGluR sub-types, which initiate gating upon binding of agonists. We design fluorescence probes to measure domain motions through nanosecond fluorescence correlation spectroscopy. We observe a broad kinetic spectrum of LBD dynamics that underlie activation of iGluRs. Microsecond clamshell motions slow upon dimerization and freeze upon binding of full and partial agonists. We uncover allosteric coupling within NMDA LBD hetero-dimers, where binding of L-glutamate to the GluN2A LBD stalls clamshell motions of the glycine-binding GluN1 LBD. Our results reveal rapid LBD dynamics across iGluRs and suggest a mechanism of negative allosteric cooperativity in NMDA receptors.}, author = {Rajab, Suhaila and Bismin, Leah and Schwarze, Simone and Pinggera, Alexandra and Greger, Ingo H. and Neuweiler, Hannes}, journal = {Communications Biology}, keywords = {hannes}, number = 1, pages = {1056–}, title = {Allosteric coupling of sub-millisecond clamshell motions in ionotropic glutamate receptor ligand-binding domains}, volume = 4, year = 2021 }

%0 Journal Article %1 rajab2021allosteric %A Rajab, Suhaila %A Bismin, Leah %A Schwarze, Simone %A Pinggera, Alexandra %A Greger, Ingo H. %A Neuweiler, Hannes %D 2021 %J Communications Biology %N 1 %P 1056-- %R 10.1038/s42003-021-02605-0 %T Allosteric coupling of sub-millisecond clamshell motions in ionotropic glutamate receptor ligand-binding domains %U https://doi.org/10.1038/s42003-021-02605-0 %V 4 %X Ionotropic glutamate receptors (iGluRs) mediate signal transmission in the brain and are important drug targets. Structural studies show snapshots of iGluRs, which provide a mechanistic understanding of gating, yet the rapid motions driving the receptor machinery are largely elusive. Here we detect kinetics of conformational change of isolated clamshell-shaped ligand-binding domains (LBDs) from the three major iGluR sub-types, which initiate gating upon binding of agonists. We design fluorescence probes to measure domain motions through nanosecond fluorescence correlation spectroscopy. We observe a broad kinetic spectrum of LBD dynamics that underlie activation of iGluRs. Microsecond clamshell motions slow upon dimerization and freeze upon binding of full and partial agonists. We uncover allosteric coupling within NMDA LBD hetero-dimers, where binding of L-glutamate to the GluN2A LBD stalls clamshell motions of the glycine-binding GluN1 LBD. Our results reveal rapid LBD dynamics across iGluRs and suggest a mechanism of negative allosteric cooperativity in NMDA receptors.
Acidosis-induced activation of anion channel SLAH3 in the flooding-related stress response of Arabidopsis Lehmann, Julian; Jørgensen, Morten E.; Fratz, Stefanie; Müller, Heike M.; Kusch, Jana; Scherzer, Sönke; Navarro-Retamal, Carlos; Mayer, Dominik; Böhm, Jennifer; Konrad, Kai R.; Terpitz, Ulrich; Dreyer, Ingo; Mueller, Thomas D.; Sauer, Markus; Hedrich, Rainer; Geiger, Dietmar; Maierhofer, Tobias in Current Biology (2021).
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Summary Plants, as sessile organisms, gained the ability to sense and respond to biotic and abiotic stressors to survive severe changes in their environments. The change in our climate comes with extreme dry periods but also episodes of flooding. The latter stress condition causes anaerobiosis-triggered cytosolic acidosis and impairs plant function. The molecular mechanism that enables plant cells to sense acidity and convey this signal via membrane depolarization was previously unknown. Here, we show that acidosis-induced anion efflux from Arabidopsis (Arabidopsis thaliana) roots is dependent on the S-type anion channel AtSLAH3. Heterologous expression of SLAH3 in Xenopus oocytes revealed that the anion channel is directly activated by a small, physiological drop in cytosolic pH. Acidosis-triggered activation of SLAH3 is mediated by protonation of histidine 330 and 454. Super-resolution microscopy analysis showed that the increase in cellular proton concentration switches SLAH3 from an electrically silent channel dimer into its active monomeric form. Our results show that, upon acidification, protons directly switch SLAH3 to its open configuration, bypassing kinase-dependent activation. Moreover, under flooding conditions, the stress response of Arabidopsis wild-type (WT) plants was significantly higher compared to SLAH3 loss-of-function mutants. Our genetic evidence of SLAH3 pH sensor function may guide the development of crop varieties with improved stress tolerance.

@article{lehmann2021acidosisinduced, abstract = {Summary Plants, as sessile organisms, gained the ability to sense and respond to biotic and abiotic stressors to survive severe changes in their environments. The change in our climate comes with extreme dry periods but also episodes of flooding. The latter stress condition causes anaerobiosis-triggered cytosolic acidosis and impairs plant function. The molecular mechanism that enables plant cells to sense acidity and convey this signal via membrane depolarization was previously unknown. Here, we show that acidosis-induced anion efflux from Arabidopsis (Arabidopsis thaliana) roots is dependent on the S-type anion channel AtSLAH3. Heterologous expression of SLAH3 in Xenopus oocytes revealed that the anion channel is directly activated by a small, physiological drop in cytosolic pH. Acidosis-triggered activation of SLAH3 is mediated by protonation of histidine 330 and 454. Super-resolution microscopy analysis showed that the increase in cellular proton concentration switches SLAH3 from an electrically silent channel dimer into its active monomeric form. Our results show that, upon acidification, protons directly switch SLAH3 to its open configuration, bypassing kinase-dependent activation. Moreover, under flooding conditions, the stress response of Arabidopsis wild-type (WT) plants was significantly higher compared to SLAH3 loss-of-function mutants. Our genetic evidence of SLAH3 pH sensor function may guide the development of crop varieties with improved stress tolerance.}, author = {Lehmann, Julian and Jørgensen, Morten E. and Fratz, Stefanie and Müller, Heike M. and Kusch, Jana and Scherzer, Sönke and Navarro-Retamal, Carlos and Mayer, Dominik and Böhm, Jennifer and Konrad, Kai R. and Terpitz, Ulrich and Dreyer, Ingo and Mueller, Thomas D. and Sauer, Markus and Hedrich, Rainer and Geiger, Dietmar and Maierhofer, Tobias}, journal = {Current Biology}, keywords = {terpitz}, title = {Acidosis-induced activation of anion channel SLAH3 in the flooding-related stress response of Arabidopsis}, year = 2021 }

%0 Journal Article %1 lehmann2021acidosisinduced %A Lehmann, Julian %A Jørgensen, Morten E. %A Fratz, Stefanie %A Müller, Heike M. %A Kusch, Jana %A Scherzer, Sönke %A Navarro-Retamal, Carlos %A Mayer, Dominik %A Böhm, Jennifer %A Konrad, Kai R. %A Terpitz, Ulrich %A Dreyer, Ingo %A Mueller, Thomas D. %A Sauer, Markus %A Hedrich, Rainer %A Geiger, Dietmar %A Maierhofer, Tobias %D 2021 %J Current Biology %R https://doi.org/10.1016/j.cub.2021.06.018 %T Acidosis-induced activation of anion channel SLAH3 in the flooding-related stress response of Arabidopsis %U https://www.sciencedirect.com/science/article/pii/S0960982221008137 %X Summary Plants, as sessile organisms, gained the ability to sense and respond to biotic and abiotic stressors to survive severe changes in their environments. The change in our climate comes with extreme dry periods but also episodes of flooding. The latter stress condition causes anaerobiosis-triggered cytosolic acidosis and impairs plant function. The molecular mechanism that enables plant cells to sense acidity and convey this signal via membrane depolarization was previously unknown. Here, we show that acidosis-induced anion efflux from Arabidopsis (Arabidopsis thaliana) roots is dependent on the S-type anion channel AtSLAH3. Heterologous expression of SLAH3 in Xenopus oocytes revealed that the anion channel is directly activated by a small, physiological drop in cytosolic pH. Acidosis-triggered activation of SLAH3 is mediated by protonation of histidine 330 and 454. Super-resolution microscopy analysis showed that the increase in cellular proton concentration switches SLAH3 from an electrically silent channel dimer into its active monomeric form. Our results show that, upon acidification, protons directly switch SLAH3 to its open configuration, bypassing kinase-dependent activation. Moreover, under flooding conditions, the stress response of Arabidopsis wild-type (WT) plants was significantly higher compared to SLAH3 loss-of-function mutants. Our genetic evidence of SLAH3 pH sensor function may guide the development of crop varieties with improved stress tolerance.
Chapter 15 - Ex-dSTORM and automated quantitative image analysis of expanded filamentous structures Zwettler, Fabian U.; Reinhard, Sebastian; Sauer, Markus in Expansion Microscopy for Cell Biology, P. Guichard, V. Hamel (Hrsg.) (2021). (Bd. 161) 317–340.
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This chapter provides a step-by-step protocol how to prepare expansion microcoscopy (ExM) treated biological samples for imaging with single-molecule localization microscopy (SMLM). For this purpose, the protocol describes the stabilization of expanded hydrogels that enables addition of photoswitching buffer without shrinkage of the sample. In addition, a guide for automated image analysis and expansion factor determination of expanded fiber-like structures is provided at the end of the chapter.

@inbook{zwettler2021chapter, abstract = {This chapter provides a step-by-step protocol how to prepare expansion microcoscopy (ExM) treated biological samples for imaging with single-molecule localization microscopy (SMLM). For this purpose, the protocol describes the stabilization of expanded hydrogels that enables addition of photoswitching buffer without shrinkage of the sample. In addition, a guide for automated image analysis and expansion factor determination of expanded fiber-like structures is provided at the end of the chapter.}, author = {Zwettler, Fabian U. and Reinhard, Sebastian and Sauer, Markus}, booktitle = {Expansion Microscopy for Cell Biology}, editor = {Guichard, Paul and Hamel, Virginie}, keywords = {sauer}, pages = {317–340}, publisher = {Academic Press}, title = {Chapter 15 - Ex-dSTORM and automated quantitative image analysis of expanded filamentous structures}, volume = 161, year = 2021 }

%0 Book Section %1 zwettler2021chapter %A Zwettler, Fabian U. %A Reinhard, Sebastian %A Sauer, Markus %B Expansion Microscopy for Cell Biology %D 2021 %E Guichard, Paul %E Hamel, Virginie %I Academic Press %P 317--340 %R https://doi.org/10.1016/bs.mcb.2020.05.004 %T Chapter 15 - Ex-dSTORM and automated quantitative image analysis of expanded filamentous structures %U https://www.sciencedirect.com/science/article/pii/S0091679X20301126 %V 161 %X This chapter provides a step-by-step protocol how to prepare expansion microcoscopy (ExM) treated biological samples for imaging with single-molecule localization microscopy (SMLM). For this purpose, the protocol describes the stabilization of expanded hydrogels that enables addition of photoswitching buffer without shrinkage of the sample. In addition, a guide for automated image analysis and expansion factor determination of expanded fiber-like structures is provided at the end of the chapter.
Tethered agonist exposure in intact adhesion/class B2 GPCRs through intrinsic structural flexibility of the GAIN domain Beliu, Gerti; Altrichter, Steffen; Guixà-González, Ramon; Hemberger, Mareike; Brauer, Ina; Dahse, Anne-Kristin; Scholz, Nicole; Wieduwild, Robert; Kuhlemann, Alexander; Batebi, Hossein; Seufert, Florian; Pérez-Hernández, Guillermo; Hildebrand, Peter W.; Sauer, Markus; Langenhan, Tobias in Molecular Cell (2021). 81(5) 905–921.e5.
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Summary Adhesion G protein-coupled receptors (aGPCRs)/family B2 GPCRs execute critical tasks during development and the operation of organs, and their genetic lesions are associated with human disorders, including cancers. Exceptional structural aGPCR features are the presence of a tethered agonist (TA) concealed within a GPCR autoproteolysis-inducing (GAIN) domain and their non-covalent heteromeric two-subunit layout. How the TA is poised for activation while maintaining this delicate receptor architecture is central to conflicting signaling paradigms that either involve or exclude aGPCR heterodimer separation. We investigated this matter in five mammalian aGPCR homologs (ADGRB3, ADGRE2, ADGRE5, ADGRG1, and ADGRL1) and demonstrate that intact aGPCR heterodimers exist at the cell surface, that the core TA region becomes unmasked in the cleaved GAIN domain, and that intra-GAIN domain movements regulate the level of tethered agonist exposure, thereby likely controlling aGPCR activity. Collectively, these findings delineate a unifying mechanism for TA-dependent signaling of intact aGPCRs.

@article{beliu2021tethered, abstract = {Summary Adhesion G protein-coupled receptors (aGPCRs)/family B2 GPCRs execute critical tasks during development and the operation of organs, and their genetic lesions are associated with human disorders, including cancers. Exceptional structural aGPCR features are the presence of a tethered agonist (TA) concealed within a GPCR autoproteolysis-inducing (GAIN) domain and their non-covalent heteromeric two-subunit layout. How the TA is poised for activation while maintaining this delicate receptor architecture is central to conflicting signaling paradigms that either involve or exclude aGPCR heterodimer separation. We investigated this matter in five mammalian aGPCR homologs (ADGRB3, ADGRE2, ADGRE5, ADGRG1, and ADGRL1) and demonstrate that intact aGPCR heterodimers exist at the cell surface, that the core TA region becomes unmasked in the cleaved GAIN domain, and that intra-GAIN domain movements regulate the level of tethered agonist exposure, thereby likely controlling aGPCR activity. Collectively, these findings delineate a unifying mechanism for TA-dependent signaling of intact aGPCRs.}, author = {Beliu, Gerti and Altrichter, Steffen and Guixà-González, Ramon and Hemberger, Mareike and Brauer, Ina and Dahse, Anne-Kristin and Scholz, Nicole and Wieduwild, Robert and Kuhlemann, Alexander and Batebi, Hossein and Seufert, Florian and Pérez-Hernández, Guillermo and Hildebrand, Peter W. and Sauer, Markus and Langenhan, Tobias}, journal = {Molecular Cell}, keywords = {sauer}, number = 5, pages = {905–921.e5}, title = {Tethered agonist exposure in intact adhesion/class B2 GPCRs through intrinsic structural flexibility of the GAIN domain}, volume = 81, year = 2021 }

%0 Journal Article %1 beliu2021tethered %A Beliu, Gerti %A Altrichter, Steffen %A Guixà-González, Ramon %A Hemberger, Mareike %A Brauer, Ina %A Dahse, Anne-Kristin %A Scholz, Nicole %A Wieduwild, Robert %A Kuhlemann, Alexander %A Batebi, Hossein %A Seufert, Florian %A Pérez-Hernández, Guillermo %A Hildebrand, Peter W. %A Sauer, Markus %A Langenhan, Tobias %D 2021 %J Molecular Cell %N 5 %P 905--921.e5 %R https://doi.org/10.1016/j.molcel.2020.12.042 %T Tethered agonist exposure in intact adhesion/class B2 GPCRs through intrinsic structural flexibility of the GAIN domain %U https://www.sciencedirect.com/science/article/pii/S1097276520309631 %V 81 %X Summary Adhesion G protein-coupled receptors (aGPCRs)/family B2 GPCRs execute critical tasks during development and the operation of organs, and their genetic lesions are associated with human disorders, including cancers. Exceptional structural aGPCR features are the presence of a tethered agonist (TA) concealed within a GPCR autoproteolysis-inducing (GAIN) domain and their non-covalent heteromeric two-subunit layout. How the TA is poised for activation while maintaining this delicate receptor architecture is central to conflicting signaling paradigms that either involve or exclude aGPCR heterodimer separation. We investigated this matter in five mammalian aGPCR homologs (ADGRB3, ADGRE2, ADGRE5, ADGRG1, and ADGRL1) and demonstrate that intact aGPCR heterodimers exist at the cell surface, that the core TA region becomes unmasked in the cleaved GAIN domain, and that intra-GAIN domain movements regulate the level of tethered agonist exposure, thereby likely controlling aGPCR activity. Collectively, these findings delineate a unifying mechanism for TA-dependent signaling of intact aGPCRs.
Targeted volumetric single-molecule localization microscopy of defined presynaptic structures in brain sections Pauli, Martin; Paul, Mila M.; Proppert, Sven; Mrestani, Achmed; Sharifi, Marzieh; Repp, Felix; Kürzinger, Lydia; Kollmannsberger, Philip; Sauer, Markus; Heckmann, Manfred; Sirén, Anna-Leena in Communications Biology (2021). 4(1) 407-.
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Revealing the molecular organization of anatomically precisely defined brain regions is necessary for refined understanding of synaptic plasticity. Although three-dimensional (3D) single-molecule localization microscopy can provide the required resolution, imaging more than a few micrometers deep into tissue remains challenging. To quantify presynaptic active zones (AZ) of entire, large, conditional detonator hippocampal mossy fiber (MF) boutons with diameters as large as 10 µm, we developed a method for targeted volumetric direct stochastic optical reconstruction microscopy (dSTORM). An optimized protocol for fast repeated axial scanning and efficient sequential labeling of the AZ scaffold Bassoon and membrane bound GFP with Alexa Fluor 647 enabled 3D-dSTORM imaging of 25 µm thick mouse brain sections and assignment of AZs to specific neuronal substructures. Quantitative data analysis revealed large differences in Bassoon cluster size and density for distinct hippocampal regions with largest clusters in MF boutons.

@article{pauli2021targeted, abstract = {Revealing the molecular organization of anatomically precisely defined brain regions is necessary for refined understanding of synaptic plasticity. Although three-dimensional (3D) single-molecule localization microscopy can provide the required resolution, imaging more than a few micrometers deep into tissue remains challenging. To quantify presynaptic active zones (AZ) of entire, large, conditional detonator hippocampal mossy fiber (MF) boutons with diameters as large as 10 µm, we developed a method for targeted volumetric direct stochastic optical reconstruction microscopy (dSTORM). An optimized protocol for fast repeated axial scanning and efficient sequential labeling of the AZ scaffold Bassoon and membrane bound GFP with Alexa Fluor 647 enabled 3D-dSTORM imaging of 25 µm thick mouse brain sections and assignment of AZs to specific neuronal substructures. Quantitative data analysis revealed large differences in Bassoon cluster size and density for distinct hippocampal regions with largest clusters in MF boutons.}, author = {Pauli, Martin and Paul, Mila M. and Proppert, Sven and Mrestani, Achmed and Sharifi, Marzieh and Repp, Felix and Kürzinger, Lydia and Kollmannsberger, Philip and Sauer, Markus and Heckmann, Manfred and Sirén, Anna-Leena}, journal = {Communications Biology}, keywords = {sauer}, number = 1, pages = {407–}, title = {Targeted volumetric single-molecule localization microscopy of defined presynaptic structures in brain sections}, volume = 4, year = 2021 }

%0 Journal Article %1 pauli2021targeted %A Pauli, Martin %A Paul, Mila M. %A Proppert, Sven %A Mrestani, Achmed %A Sharifi, Marzieh %A Repp, Felix %A Kürzinger, Lydia %A Kollmannsberger, Philip %A Sauer, Markus %A Heckmann, Manfred %A Sirén, Anna-Leena %D 2021 %J Communications Biology %N 1 %P 407-- %R 10.1038/s42003-021-01939-z %T Targeted volumetric single-molecule localization microscopy of defined presynaptic structures in brain sections %U https://doi.org/10.1038/s42003-021-01939-z %V 4 %X Revealing the molecular organization of anatomically precisely defined brain regions is necessary for refined understanding of synaptic plasticity. Although three-dimensional (3D) single-molecule localization microscopy can provide the required resolution, imaging more than a few micrometers deep into tissue remains challenging. To quantify presynaptic active zones (AZ) of entire, large, conditional detonator hippocampal mossy fiber (MF) boutons with diameters as large as 10 µm, we developed a method for targeted volumetric direct stochastic optical reconstruction microscopy (dSTORM). An optimized protocol for fast repeated axial scanning and efficient sequential labeling of the AZ scaffold Bassoon and membrane bound GFP with Alexa Fluor 647 enabled 3D-dSTORM imaging of 25 µm thick mouse brain sections and assignment of AZs to specific neuronal substructures. Quantitative data analysis revealed large differences in Bassoon cluster size and density for distinct hippocampal regions with largest clusters in MF boutons.
The impact of episporic modification of Lichtheimia corymbifera on virulence and interaction with phagocytes Hassan, Mohamed I. Abdelwahab; Keller, Monique; Hillger, Michael; Binder, Ulrike; Reuter, Stefanie; Herold, Kristina; Telagathoti, Anusha; Dahse, Hans-Martin; Wicht, Saiedeh; Trinks, Nora; Nietzsche, Sandor; Deckert-Gaudig, Tanja; Deckert, Volker; Mrowka, Ralf; Terpitz, Ulrich; {Peter Saluz}, Hans; Voigt, Kerstin in Computational and Structural Biotechnology Journal (2021). 19 880–896.
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Fungal infections caused by the ancient lineage Mucorales are emerging and increasingly reported in humans. Comprehensive surveys on promising attributes from a multitude of possible virulence factors are limited and so far, focused on Mucor and Rhizopus. This study addresses a systematic approach to monitor phagocytosis after physical and enzymatic modification of the outer spore wall of Lichtheimia corymbifera, one of the major causative agents of mucormycosis. Episporic modifications were performed and their consequences on phagocytosis, intracellular survival and virulence by murine alveolar macrophages and in an invertebrate infection model were elucidated. While depletion of lipids did not affect the phagocytosis of both strains, delipidation led to attenuation of LCA strain but appears to be dispensable for infection with LCV strain in the settings used in this study. Combined glucano-proteolytic treatment was necessary to achieve a significant decrease of virulence of the LCV strain in Galleria mellonella during maintenance of the full potential for spore germination as shown by a novel automated germination assay. Proteolytic and glucanolytic treatments largely increased phagocytosis compared to alive resting and swollen spores. Whilst resting spores barely (1–2%) fuse to lysosomes after invagination in to phagosomes, spore trypsinization led to a 10-fold increase of phagolysosomal fusion as measured by intracellular acidification. This is the first report of a polyphasic measurement of the consequences of episporic modification of a mucormycotic pathogen in spore germination, spore surface ultrastructure, phagocytosis, stimulation of Toll-like receptors (TLRs), phagolysosomal fusion and intracellular acidification, apoptosis, generation of reactive oxygen species (ROS) and virulence.

@article{HASSAN2021880, abstract = {Fungal infections caused by the ancient lineage Mucorales are emerging and increasingly reported in humans. Comprehensive surveys on promising attributes from a multitude of possible virulence factors are limited and so far, focused on Mucor and Rhizopus. This study addresses a systematic approach to monitor phagocytosis after physical and enzymatic modification of the outer spore wall of Lichtheimia corymbifera, one of the major causative agents of mucormycosis. Episporic modifications were performed and their consequences on phagocytosis, intracellular survival and virulence by murine alveolar macrophages and in an invertebrate infection model were elucidated. While depletion of lipids did not affect the phagocytosis of both strains, delipidation led to attenuation of LCA strain but appears to be dispensable for infection with LCV strain in the settings used in this study. Combined glucano-proteolytic treatment was necessary to achieve a significant decrease of virulence of the LCV strain in Galleria mellonella during maintenance of the full potential for spore germination as shown by a novel automated germination assay. Proteolytic and glucanolytic treatments largely increased phagocytosis compared to alive resting and swollen spores. Whilst resting spores barely (1–2%) fuse to lysosomes after invagination in to phagosomes, spore trypsinization led to a 10-fold increase of phagolysosomal fusion as measured by intracellular acidification. This is the first report of a polyphasic measurement of the consequences of episporic modification of a mucormycotic pathogen in spore germination, spore surface ultrastructure, phagocytosis, stimulation of Toll-like receptors (TLRs), phagolysosomal fusion and intracellular acidification, apoptosis, generation of reactive oxygen species (ROS) and virulence.}, author = {Hassan, Mohamed I. Abdelwahab and Keller, Monique and Hillger, Michael and Binder, Ulrike and Reuter, Stefanie and Herold, Kristina and Telagathoti, Anusha and Dahse, Hans-Martin and Wicht, Saiedeh and Trinks, Nora and Nietzsche, Sandor and Deckert-Gaudig, Tanja and Deckert, Volker and Mrowka, Ralf and Terpitz, Ulrich and {Peter Saluz}, Hans and Voigt, Kerstin}, journal = {Computational and Structural Biotechnology Journal}, keywords = {terpitz}, pages = {880 - 896}, title = {The impact of episporic modification of Lichtheimia corymbifera on virulence and interaction with phagocytes}, volume = 19, year = 2021 }

%0 Journal Article %1 HASSAN2021880 %A Hassan, Mohamed I. Abdelwahab %A Keller, Monique %A Hillger, Michael %A Binder, Ulrike %A Reuter, Stefanie %A Herold, Kristina %A Telagathoti, Anusha %A Dahse, Hans-Martin %A Wicht, Saiedeh %A Trinks, Nora %A Nietzsche, Sandor %A Deckert-Gaudig, Tanja %A Deckert, Volker %A Mrowka, Ralf %A Terpitz, Ulrich %A {Peter Saluz}, Hans %A Voigt, Kerstin %D 2021 %J Computational and Structural Biotechnology Journal %P 880 - 896 %R https://doi.org/10.1016/j.csbj.2021.01.023 %T The impact of episporic modification of Lichtheimia corymbifera on virulence and interaction with phagocytes %U https://doi.org/10.1016/j.csbj.2021.01.023 %V 19 %X Fungal infections caused by the ancient lineage Mucorales are emerging and increasingly reported in humans. Comprehensive surveys on promising attributes from a multitude of possible virulence factors are limited and so far, focused on Mucor and Rhizopus. This study addresses a systematic approach to monitor phagocytosis after physical and enzymatic modification of the outer spore wall of Lichtheimia corymbifera, one of the major causative agents of mucormycosis. Episporic modifications were performed and their consequences on phagocytosis, intracellular survival and virulence by murine alveolar macrophages and in an invertebrate infection model were elucidated. While depletion of lipids did not affect the phagocytosis of both strains, delipidation led to attenuation of LCA strain but appears to be dispensable for infection with LCV strain in the settings used in this study. Combined glucano-proteolytic treatment was necessary to achieve a significant decrease of virulence of the LCV strain in Galleria mellonella during maintenance of the full potential for spore germination as shown by a novel automated germination assay. Proteolytic and glucanolytic treatments largely increased phagocytosis compared to alive resting and swollen spores. Whilst resting spores barely (1–2%) fuse to lysosomes after invagination in to phagosomes, spore trypsinization led to a 10-fold increase of phagolysosomal fusion as measured by intracellular acidification. This is the first report of a polyphasic measurement of the consequences of episporic modification of a mucormycotic pathogen in spore germination, spore surface ultrastructure, phagocytosis, stimulation of Toll-like receptors (TLRs), phagolysosomal fusion and intracellular acidification, apoptosis, generation of reactive oxygen species (ROS) and virulence.
High-throughput determination of protein affinities using unmodified peptide libraries in nanomolar scale Schulte, Clemens; Khayenko, Vladimir; Nordblom, Noah Frieder; Tippel, Franziska; Peck, Violetta; Gupta, Amit Jean; Maric, Hans Michael in iScience (2021). 24(1) 101898-.
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Protein-protein interactions (PPIs) are of fundamental importance for our understanding of physiology and pathology. PPIs involving short, linear motifs play a major role in immunological recognition, signaling, and regulation and provide attractive starting points for pharmaceutical intervention. Yet, state-of-the-art protein-peptide affinity determination approaches exhibit limited throughput and sensitivity, often resulting from ligand immobilization, labeling, or synthesis. Here, we introduce a high-throughput method for in-solution analysis of protein-peptide interactions using a phenomenon called temperature related intensity change (TRIC). We use TRIC for the identification and fine-mapping of low- and high-affinity protein interaction sites and the definition of sequence binding requirements. Validation is achieved by microarray-based studies using wild-type and mutated recombinant protein and the native protein within tissue lysates. On-chip neutralization and strong correlation with structural data establish TRIC as a quasi-label-free method to determine binding affinities of unmodified peptide libraries with large dynamic range.

@article{schulte2021highthroughput, abstract = {Protein-protein interactions (PPIs) are of fundamental importance for our understanding of physiology and pathology. PPIs involving short, linear motifs play a major role in immunological recognition, signaling, and regulation and provide attractive starting points for pharmaceutical intervention. Yet, state-of-the-art protein-peptide affinity determination approaches exhibit limited throughput and sensitivity, often resulting from ligand immobilization, labeling, or synthesis. Here, we introduce a high-throughput method for in-solution analysis of protein-peptide interactions using a phenomenon called temperature related intensity change (TRIC). We use TRIC for the identification and fine-mapping of low- and high-affinity protein interaction sites and the definition of sequence binding requirements. Validation is achieved by microarray-based studies using wild-type and mutated recombinant protein and the native protein within tissue lysates. On-chip neutralization and strong correlation with structural data establish TRIC as a quasi-label-free method to determine binding affinities of unmodified peptide libraries with large dynamic range.}, author = {Schulte, Clemens and Khayenko, Vladimir and Nordblom, Noah Frieder and Tippel, Franziska and Peck, Violetta and Gupta, Amit Jean and Maric, Hans Michael}, journal = {iScience}, keywords = {maric}, number = 1, pages = {101898–}, title = {High-throughput determination of protein affinities using unmodified peptide libraries in nanomolar scale}, volume = 24, year = 2021 }

%0 Journal Article %1 schulte2021highthroughput %A Schulte, Clemens %A Khayenko, Vladimir %A Nordblom, Noah Frieder %A Tippel, Franziska %A Peck, Violetta %A Gupta, Amit Jean %A Maric, Hans Michael %D 2021 %J iScience %N 1 %P 101898-- %R https://doi.org/10.1016/j.isci.2020.101898 %T High-throughput determination of protein affinities using unmodified peptide libraries in nanomolar scale %U https://www.sciencedirect.com/science/article/pii/S2589004220310956 %V 24 %X Protein-protein interactions (PPIs) are of fundamental importance for our understanding of physiology and pathology. PPIs involving short, linear motifs play a major role in immunological recognition, signaling, and regulation and provide attractive starting points for pharmaceutical intervention. Yet, state-of-the-art protein-peptide affinity determination approaches exhibit limited throughput and sensitivity, often resulting from ligand immobilization, labeling, or synthesis. Here, we introduce a high-throughput method for in-solution analysis of protein-peptide interactions using a phenomenon called temperature related intensity change (TRIC). We use TRIC for the identification and fine-mapping of low- and high-affinity protein interaction sites and the definition of sequence binding requirements. Validation is achieved by microarray-based studies using wild-type and mutated recombinant protein and the native protein within tissue lysates. On-chip neutralization and strong correlation with structural data establish TRIC as a quasi-label-free method to determine binding affinities of unmodified peptide libraries with large dynamic range.
Hydroxamic acid-modified peptide microarrays for profiling isozyme-selective interactions and inhibition of histone deacetylases Moreno-Yruela, Carlos; Bæk, Michael; Vrsanova, Adela-Eugenie; Schulte, Clemens; Maric, Hans M.; Olsen, Christian A. in Nature Communications (2021). 12(1) 62-.
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Histones control gene expression by regulating chromatin structure and function. The posttranslational modifications (PTMs) on the side chains of histones form the epigenetic landscape, which is tightly controlled by epigenetic modulator enzymes and further recognized by so-called reader domains. Histone microarrays have been widely applied to investigate histone–reader interactions, but not the transient interactions of Zn2+-dependent histone deacetylase (HDAC) eraser enzymes. Here, we synthesize hydroxamic acid-modified histone peptides and use them in femtomolar microarrays for the direct capture and detection of the four class I HDAC isozymes. Follow-up functional assays in solution provide insights into their suitability to discover HDAC substrates and inhibitors with nanomolar potency and activity in cellular assays. We conclude that similar hydroxamic acid-modified histone peptide microarrays and libraries could find broad application to identify class I HDAC isozyme-specific substrates and facilitate the development of isozyme-selective HDAC inhibitors and probes.

@article{morenoyruela2021hydroxamic, abstract = {Histones control gene expression by regulating chromatin structure and function. The posttranslational modifications (PTMs) on the side chains of histones form the epigenetic landscape, which is tightly controlled by epigenetic modulator enzymes and further recognized by so-called reader domains. Histone microarrays have been widely applied to investigate histone–reader interactions, but not the transient interactions of Zn2+-dependent histone deacetylase (HDAC) eraser enzymes. Here, we synthesize hydroxamic acid-modified histone peptides and use them in femtomolar microarrays for the direct capture and detection of the four class I HDAC isozymes. Follow-up functional assays in solution provide insights into their suitability to discover HDAC substrates and inhibitors with nanomolar potency and activity in cellular assays. We conclude that similar hydroxamic acid-modified histone peptide microarrays and libraries could find broad application to identify class I HDAC isozyme-specific substrates and facilitate the development of isozyme-selective HDAC inhibitors and probes.}, author = {Moreno-Yruela, Carlos and Bæk, Michael and Vrsanova, Adela-Eugenie and Schulte, Clemens and Maric, Hans M. and Olsen, Christian A.}, journal = {Nature Communications}, keywords = {maric}, number = 1, pages = {62–}, title = {Hydroxamic acid-modified peptide microarrays for profiling isozyme-selective interactions and inhibition of histone deacetylases}, volume = 12, year = 2021 }

%0 Journal Article %1 morenoyruela2021hydroxamic %A Moreno-Yruela, Carlos %A Bæk, Michael %A Vrsanova, Adela-Eugenie %A Schulte, Clemens %A Maric, Hans M. %A Olsen, Christian A. %D 2021 %J Nature Communications %N 1 %P 62-- %R 10.1038/s41467-020-20250-9 %T Hydroxamic acid-modified peptide microarrays for profiling isozyme-selective interactions and inhibition of histone deacetylases %U https://doi.org/10.1038/s41467-020-20250-9 %V 12 %X Histones control gene expression by regulating chromatin structure and function. The posttranslational modifications (PTMs) on the side chains of histones form the epigenetic landscape, which is tightly controlled by epigenetic modulator enzymes and further recognized by so-called reader domains. Histone microarrays have been widely applied to investigate histone–reader interactions, but not the transient interactions of Zn2+-dependent histone deacetylase (HDAC) eraser enzymes. Here, we synthesize hydroxamic acid-modified histone peptides and use them in femtomolar microarrays for the direct capture and detection of the four class I HDAC isozymes. Follow-up functional assays in solution provide insights into their suitability to discover HDAC substrates and inhibitors with nanomolar potency and activity in cellular assays. We conclude that similar hydroxamic acid-modified histone peptide microarrays and libraries could find broad application to identify class I HDAC isozyme-specific substrates and facilitate the development of isozyme-selective HDAC inhibitors and probes.
Targeting the APP-Mint2 Protein–Protein Interaction with a Peptide-Based Inhibitor Reduces Amyloid-β Formation Bartling, Christian R. O.; Jensen, Thomas M. T.; Henry, Shawna M.; Colliander, Anna L.; Sereikaite, Vita; Wenzler, Marcella; Jain, Palash; Maric, Hans M.; Harpsøe, Kasper; Pedersen, Søren W.; Clemmensen, Louise S.; Haugaard-Kedström, Linda M.; Gloriam, David E.; Ho, Angela; Strømgaard, Kristian in J. Am. Chem. Soc. (2021). 143(2) 891–901.
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There is an urgent need for novel therapeutic approaches to treat Alzheimer’s disease (AD) with the ability to both alleviate the clinical symptoms and halt the progression of the disease. AD is characterized by the accumulation of amyloid-β (Aβ) peptides which are generated through the sequential proteolytic cleavage of the amyloid precursor protein (APP). Previous studies reported that Mint2, a neuronal adaptor protein binding both APP and the γ-secretase complex, affects APP processing and formation of pathogenic Aβ. However, there have been contradicting results concerning whether Mint2 has a facilitative or suppressive effect on Aβ generation. Herein, we deciphered the APP-Mint2 protein–protein interaction (PPI) via extensive probing of both backbone H-bond and side-chain interactions. We also developed a proteolytically stable, high-affinity peptide targeting the APP-Mint2 interaction. We found that both an APP binding-deficient Mint2 variant and a cell-permeable PPI inhibitor significantly reduced Aβ42 levels in a neuronal in vitro model of AD. Together, these findings demonstrate a facilitative role of Mint2 in Aβ formation, and the combination of genetic and pharmacological approaches suggests that targeting Mint2 is a promising therapeutic strategy to reduce pathogenic Aβ levels.

@article{bartling2021targeting, abstract = {There is an urgent need for novel therapeutic approaches to treat Alzheimer’s disease (AD) with the ability to both alleviate the clinical symptoms and halt the progression of the disease. AD is characterized by the accumulation of amyloid-β (Aβ) peptides which are generated through the sequential proteolytic cleavage of the amyloid precursor protein (APP). Previous studies reported that Mint2, a neuronal adaptor protein binding both APP and the γ-secretase complex, affects APP processing and formation of pathogenic Aβ. However, there have been contradicting results concerning whether Mint2 has a facilitative or suppressive effect on Aβ generation. Herein, we deciphered the APP-Mint2 protein–protein interaction (PPI) via extensive probing of both backbone H-bond and side-chain interactions. We also developed a proteolytically stable, high-affinity peptide targeting the APP-Mint2 interaction. We found that both an APP binding-deficient Mint2 variant and a cell-permeable PPI inhibitor significantly reduced Aβ42 levels in a neuronal in vitro model of AD. Together, these findings demonstrate a facilitative role of Mint2 in Aβ formation, and the combination of genetic and pharmacological approaches suggests that targeting Mint2 is a promising therapeutic strategy to reduce pathogenic Aβ levels.}, author = {Bartling, Christian R. O. and Jensen, Thomas M. T. and Henry, Shawna M. and Colliander, Anna L. and Sereikaite, Vita and Wenzler, Marcella and Jain, Palash and Maric, Hans M. and Harpsøe, Kasper and Pedersen, Søren W. and Clemmensen, Louise S. and Haugaard-Kedström, Linda M. and Gloriam, David E. and Ho, Angela and Strømgaard, Kristian}, booktitle = {Journal of the American Chemical Society}, journal = {J. Am. Chem. Soc.}, keywords = {maric}, month = {jan}, number = 2, pages = {891–901}, publisher = {American Chemical Society}, title = {Targeting the APP-Mint2 Protein–Protein Interaction with a Peptide-Based Inhibitor Reduces Amyloid-β Formation}, volume = 143, year = 2021 }

%0 Journal Article %1 bartling2021targeting %A Bartling, Christian R. O. %A Jensen, Thomas M. T. %A Henry, Shawna M. %A Colliander, Anna L. %A Sereikaite, Vita %A Wenzler, Marcella %A Jain, Palash %A Maric, Hans M. %A Harpsøe, Kasper %A Pedersen, Søren W. %A Clemmensen, Louise S. %A Haugaard-Kedström, Linda M. %A Gloriam, David E. %A Ho, Angela %A Strømgaard, Kristian %B Journal of the American Chemical Society %D 2021 %I American Chemical Society %J J. Am. Chem. Soc. %N 2 %P 891--901 %R 10.1021/jacs.0c10696 %T Targeting the APP-Mint2 Protein–Protein Interaction with a Peptide-Based Inhibitor Reduces Amyloid-β Formation %U https://doi.org/10.1021/jacs.0c10696 %V 143 %X There is an urgent need for novel therapeutic approaches to treat Alzheimer’s disease (AD) with the ability to both alleviate the clinical symptoms and halt the progression of the disease. AD is characterized by the accumulation of amyloid-β (Aβ) peptides which are generated through the sequential proteolytic cleavage of the amyloid precursor protein (APP). Previous studies reported that Mint2, a neuronal adaptor protein binding both APP and the γ-secretase complex, affects APP processing and formation of pathogenic Aβ. However, there have been contradicting results concerning whether Mint2 has a facilitative or suppressive effect on Aβ generation. Herein, we deciphered the APP-Mint2 protein–protein interaction (PPI) via extensive probing of both backbone H-bond and side-chain interactions. We also developed a proteolytically stable, high-affinity peptide targeting the APP-Mint2 interaction. We found that both an APP binding-deficient Mint2 variant and a cell-permeable PPI inhibitor significantly reduced Aβ42 levels in a neuronal in vitro model of AD. Together, these findings demonstrate a facilitative role of Mint2 in Aβ formation, and the combination of genetic and pharmacological approaches suggests that targeting Mint2 is a promising therapeutic strategy to reduce pathogenic Aβ levels.
Serotonin-specific neurons differentiated from human iPSCs form distinct subtypes with synaptic protein assembly Jansch, Charline; Ziegler, Georg C.; Forero, Andrea; Gredy, Sina; Wäldchen, Sina; Vitale, Maria Rosaria; Svirin, Evgeniy; Zöller, Johanna E. M.; Waider, Jonas; Günther, Katharina; Edenhofer, Frank; Sauer, Markus; Wischmeyer, Erhard; Lesch, Klaus-Peter in Journal of Neural Transmission (2021). 128(2) 225–241.
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Human induced pluripotent stem cells (hiPSCs) have revolutionized the generation of experimental disease models, but the development of protocols for the differentiation of functionally active neuronal subtypes with defined specification is still in its infancy. While dysfunction of the brain serotonin (5-HT) system has been implicated in the etiology of various neuropsychiatric disorders, investigation of functional human 5-HT specific neurons in vitro has been restricted by technical limitations. We describe an efficient generation of functionally active neurons from hiPSCs displaying 5-HT specification by modification of a previously reported protocol. Furthermore, 5-HT specific neurons were characterized using high-end fluorescence imaging including super-resolution microscopy in combination with electrophysiological techniques. Differentiated hiPSCs synthesize 5-HT, express specific markers, such as tryptophan hydroxylase 2 and 5-HT transporter, and exhibit an electrophysiological signature characteristic of serotonergic neurons, with spontaneous rhythmic activities, broad action potentials and large afterhyperpolarization potentials. 5-HT specific neurons form synapses reflected by the expression of pre- and postsynaptic proteins, such as Bassoon and Homer. The distribution pattern of Bassoon, a marker of the active zone along the soma and extensions of neurons, indicates functionality via volume transmission. Among the high percentage of 5-HT specific neurons (~ 42%), a subpopulation of CDH13 + cells presumably designates dorsal raphe neurons. hiPSC-derived 5-HT specific neuronal cell cultures reflect the heterogeneous nature of dorsal and median raphe nuclei and may facilitate examining the association of serotonergic neuron subpopulations with neuropsychiatric disorders.

@article{jansch2021serotoninspecific, abstract = {Human induced pluripotent stem cells (hiPSCs) have revolutionized the generation of experimental disease models, but the development of protocols for the differentiation of functionally active neuronal subtypes with defined specification is still in its infancy. While dysfunction of the brain serotonin (5-HT) system has been implicated in the etiology of various neuropsychiatric disorders, investigation of functional human 5-HT specific neurons in vitro has been restricted by technical limitations. We describe an efficient generation of functionally active neurons from hiPSCs displaying 5-HT specification by modification of a previously reported protocol. Furthermore, 5-HT specific neurons were characterized using high-end fluorescence imaging including super-resolution microscopy in combination with electrophysiological techniques. Differentiated hiPSCs synthesize 5-HT, express specific markers, such as tryptophan hydroxylase 2 and 5-HT transporter, and exhibit an electrophysiological signature characteristic of serotonergic neurons, with spontaneous rhythmic activities, broad action potentials and large afterhyperpolarization potentials. 5-HT specific neurons form synapses reflected by the expression of pre- and postsynaptic proteins, such as Bassoon and Homer. The distribution pattern of Bassoon, a marker of the active zone along the soma and extensions of neurons, indicates functionality via volume transmission. Among the high percentage of 5-HT specific neurons ( 42%), a subpopulation of CDH13 + cells presumably designates dorsal raphe neurons. hiPSC-derived 5-HT specific neuronal cell cultures reflect the heterogeneous nature of dorsal and median raphe nuclei and may facilitate examining the association of serotonergic neuron subpopulations with neuropsychiatric disorders.}, author = {Jansch, Charline and Ziegler, Georg C. and Forero, Andrea and Gredy, Sina and Wäldchen, Sina and Vitale, Maria Rosaria and Svirin, Evgeniy and Zöller, Johanna E. M. and Waider, Jonas and Günther, Katharina and Edenhofer, Frank and Sauer, Markus and Wischmeyer, Erhard and Lesch, Klaus-Peter}, journal = {Journal of Neural Transmission}, keywords = {sauer}, number = 2, pages = {225–241}, title = {Serotonin-specific neurons differentiated from human iPSCs form distinct subtypes with synaptic protein assembly}, volume = 128, year = 2021 }

%0 Journal Article %1 jansch2021serotoninspecific %A Jansch, Charline %A Ziegler, Georg C. %A Forero, Andrea %A Gredy, Sina %A Wäldchen, Sina %A Vitale, Maria Rosaria %A Svirin, Evgeniy %A Zöller, Johanna E. M. %A Waider, Jonas %A Günther, Katharina %A Edenhofer, Frank %A Sauer, Markus %A Wischmeyer, Erhard %A Lesch, Klaus-Peter %D 2021 %J Journal of Neural Transmission %N 2 %P 225--241 %R 10.1007/s00702-021-02303-5 %T Serotonin-specific neurons differentiated from human iPSCs form distinct subtypes with synaptic protein assembly %U https://doi.org/10.1007/s00702-021-02303-5 %V 128 %X Human induced pluripotent stem cells (hiPSCs) have revolutionized the generation of experimental disease models, but the development of protocols for the differentiation of functionally active neuronal subtypes with defined specification is still in its infancy. While dysfunction of the brain serotonin (5-HT) system has been implicated in the etiology of various neuropsychiatric disorders, investigation of functional human 5-HT specific neurons in vitro has been restricted by technical limitations. We describe an efficient generation of functionally active neurons from hiPSCs displaying 5-HT specification by modification of a previously reported protocol. Furthermore, 5-HT specific neurons were characterized using high-end fluorescence imaging including super-resolution microscopy in combination with electrophysiological techniques. Differentiated hiPSCs synthesize 5-HT, express specific markers, such as tryptophan hydroxylase 2 and 5-HT transporter, and exhibit an electrophysiological signature characteristic of serotonergic neurons, with spontaneous rhythmic activities, broad action potentials and large afterhyperpolarization potentials. 5-HT specific neurons form synapses reflected by the expression of pre- and postsynaptic proteins, such as Bassoon and Homer. The distribution pattern of Bassoon, a marker of the active zone along the soma and extensions of neurons, indicates functionality via volume transmission. Among the high percentage of 5-HT specific neurons (~ 42%), a subpopulation of CDH13 + cells presumably designates dorsal raphe neurons. hiPSC-derived 5-HT specific neuronal cell cultures reflect the heterogeneous nature of dorsal and median raphe nuclei and may facilitate examining the association of serotonergic neuron subpopulations with neuropsychiatric disorders.
Upregulation of CD38 expression on multiple myeloma cells by novel HDAC6 inhibitors is a class effect and augments the efficacy of daratumumab García-Guerrero, Estefanía; Götz, Ralph; Doose, Sören; Sauer, Markus; Rodríguez-Gil, Alfonso; Nerreter, Thomas; Kortüm, K. Martin; Pérez-Simón, José A.; Einsele, Hermann; Hudecek, Michael; Danhof, Sophia in Leukemia (2021). 35(1) 201–214.
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Multiple myeloma (MM) is incurable, so there is a significant unmet need for effective therapy for patients with relapsed or refractory disease. This situation has not changed despite the recent approval of the anti-CD38 antibody daratumumab, one of the most potent agents in MM treatment. The efficiency of daratumumab might be improved by combining it with synergistic anti-MM agents. We therefore investigated the potential of the histone deacetylase (HDAC) inhibitor ricolinostat to up-regulate CD38 on MM cells, thereby enhancing the performance of CD38-specific therapies. Using quantitative reverse transcription polymerase chain reaction and flow cytometry, we observed that ricolinostat significantly increases CD38 RNA levels and CD38 surface expression on MM cells. Super-resolution microscopy imaging of MM cells by direct stochastic optical reconstruction microscopy confirmed this rise with molecular resolution and revealed homogeneous distribution of CD38 molecules on the cell membrane. Particularly important is that combining ricolinostat with daratumumab induced enhanced lysis of MM cells. We also evaluated next-generation HDAC6 inhibitors (ACY-241, WT-161) and observed similar increase of CD38 levels suggesting that the upregulation of CD38 expression on MM cells by HDAC6 inhibitors is a class effect. This proof-of-concept illustrates the potential benefit of combining HDAC6 inhibitors and CD38-directed immunotherapy for MM treatment.

@article{garciaguerrero2021upregulation, abstract = {Multiple myeloma (MM) is incurable, so there is a significant unmet need for effective therapy for patients with relapsed or refractory disease. This situation has not changed despite the recent approval of the anti-CD38 antibody daratumumab, one of the most potent agents in MM treatment. The efficiency of daratumumab might be improved by combining it with synergistic anti-MM agents. We therefore investigated the potential of the histone deacetylase (HDAC) inhibitor ricolinostat to up-regulate CD38 on MM cells, thereby enhancing the performance of CD38-specific therapies. Using quantitative reverse transcription polymerase chain reaction and flow cytometry, we observed that ricolinostat significantly increases CD38 RNA levels and CD38 surface expression on MM cells. Super-resolution microscopy imaging of MM cells by direct stochastic optical reconstruction microscopy confirmed this rise with molecular resolution and revealed homogeneous distribution of CD38 molecules on the cell membrane. Particularly important is that combining ricolinostat with daratumumab induced enhanced lysis of MM cells. We also evaluated next-generation HDAC6 inhibitors (ACY-241, WT-161) and observed similar increase of CD38 levels suggesting that the upregulation of CD38 expression on MM cells by HDAC6 inhibitors is a class effect. This proof-of-concept illustrates the potential benefit of combining HDAC6 inhibitors and CD38-directed immunotherapy for MM treatment.}, author = {García-Guerrero, Estefanía and Götz, Ralph and Doose, Sören and Sauer, Markus and Rodríguez-Gil, Alfonso and Nerreter, Thomas and Kortüm, K. Martin and Pérez-Simón, José A. and Einsele, Hermann and Hudecek, Michael and Danhof, Sophia}, journal = {Leukemia}, keywords = {sauer}, number = 1, pages = {201–214}, title = {Upregulation of CD38 expression on multiple myeloma cells by novel HDAC6 inhibitors is a class effect and augments the efficacy of daratumumab}, volume = 35, year = 2021 }

%0 Journal Article %1 garciaguerrero2021upregulation %A García-Guerrero, Estefanía %A Götz, Ralph %A Doose, Sören %A Sauer, Markus %A Rodríguez-Gil, Alfonso %A Nerreter, Thomas %A Kortüm, K. Martin %A Pérez-Simón, José A. %A Einsele, Hermann %A Hudecek, Michael %A Danhof, Sophia %D 2021 %J Leukemia %N 1 %P 201--214 %R 10.1038/s41375-020-0840-y %T Upregulation of CD38 expression on multiple myeloma cells by novel HDAC6 inhibitors is a class effect and augments the efficacy of daratumumab %U https://doi.org/10.1038/s41375-020-0840-y %V 35 %X Multiple myeloma (MM) is incurable, so there is a significant unmet need for effective therapy for patients with relapsed or refractory disease. This situation has not changed despite the recent approval of the anti-CD38 antibody daratumumab, one of the most potent agents in MM treatment. The efficiency of daratumumab might be improved by combining it with synergistic anti-MM agents. We therefore investigated the potential of the histone deacetylase (HDAC) inhibitor ricolinostat to up-regulate CD38 on MM cells, thereby enhancing the performance of CD38-specific therapies. Using quantitative reverse transcription polymerase chain reaction and flow cytometry, we observed that ricolinostat significantly increases CD38 RNA levels and CD38 surface expression on MM cells. Super-resolution microscopy imaging of MM cells by direct stochastic optical reconstruction microscopy confirmed this rise with molecular resolution and revealed homogeneous distribution of CD38 molecules on the cell membrane. Particularly important is that combining ricolinostat with daratumumab induced enhanced lysis of MM cells. We also evaluated next-generation HDAC6 inhibitors (ACY-241, WT-161) and observed similar increase of CD38 levels suggesting that the upregulation of CD38 expression on MM cells by HDAC6 inhibitors is a class effect. This proof-of-concept illustrates the potential benefit of combining HDAC6 inhibitors and CD38-directed immunotherapy for MM treatment.
Expanding GABAAR pharmacology via receptor-associated proteins Schulte, Clemens; Maric, Hans Michael in Current Opinion in Pharmacology (2021). 57 98–106.
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Drugs directly targeting γ-aminobutyric acid type A receptors (GABAARs), the major mediators of fast synaptic inhibition, contribute significantly to today's neuropharmacology. Emerging evidence establishes intracellularly GABAAR-associated proteins as the central players in determining cellular and subcellular GABAergic input sites, thereby providing pharmacological opportunities to affect distinct receptor populations and address discrete neuronal dysfunctions. Here, we report on recently studied GABAAR-associated proteins and highlight challenges and newly available methods for their functional and physical mapping. We anticipate these efforts to contribute to decipher the complexity of GABAergic signalling in the brain and eventually enable therapeutic avenues for, so far, untreatable neuronal disorders and diseases.

@article{schulte2021expanding, abstract = {Drugs directly targeting γ-aminobutyric acid type A receptors (GABAARs), the major mediators of fast synaptic inhibition, contribute significantly to today's neuropharmacology. Emerging evidence establishes intracellularly GABAAR-associated proteins as the central players in determining cellular and subcellular GABAergic input sites, thereby providing pharmacological opportunities to affect distinct receptor populations and address discrete neuronal dysfunctions. Here, we report on recently studied GABAAR-associated proteins and highlight challenges and newly available methods for their functional and physical mapping. We anticipate these efforts to contribute to decipher the complexity of GABAergic signalling in the brain and eventually enable therapeutic avenues for, so far, untreatable neuronal disorders and diseases.}, author = {Schulte, Clemens and Maric, Hans Michael}, journal = {Current Opinion in Pharmacology}, keywords = {maric}, pages = {98–106}, title = {Expanding GABAAR pharmacology via receptor-associated proteins}, volume = 57, year = 2021 }

%0 Journal Article %1 schulte2021expanding %A Schulte, Clemens %A Maric, Hans Michael %D 2021 %J Current Opinion in Pharmacology %P 98--106 %R https://doi.org/10.1016/j.coph.2021.01.004 %T Expanding GABAAR pharmacology via receptor-associated proteins %U https://www.sciencedirect.com/science/article/pii/S1471489221000059 %V 57 %X Drugs directly targeting γ-aminobutyric acid type A receptors (GABAARs), the major mediators of fast synaptic inhibition, contribute significantly to today's neuropharmacology. Emerging evidence establishes intracellularly GABAAR-associated proteins as the central players in determining cellular and subcellular GABAergic input sites, thereby providing pharmacological opportunities to affect distinct receptor populations and address discrete neuronal dysfunctions. Here, we report on recently studied GABAAR-associated proteins and highlight challenges and newly available methods for their functional and physical mapping. We anticipate these efforts to contribute to decipher the complexity of GABAergic signalling in the brain and eventually enable therapeutic avenues for, so far, untreatable neuronal disorders and diseases.
Superagonistic CD28 stimulation induces IFN-γ release from mouse T helper 1 cells in vitro and in vivo Haack, Stephanie; Baiker, Sarah; Schlegel, Jan; Sauer, Markus; Sparwasser, Tim; Langenhorst, Daniela; Beyersdorf, Niklas in European Journal of Immunology (2021). 51(3) 738–741.
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Like human Th1 cells, mouse Th1 cells also secrete IFN-? upon stimulation with a superagonistic anti-CD28 monoclonal antibody (CD28-SA). Crosslinking of the CD28-SA via FcR and CD40-CD40L interactions greatly increased IFN-? release. Our data stress the utility of the mouse as a model organism for immune responses in humans.

@article{haack2021superagonistic, abstract = {Like human Th1 cells, mouse Th1 cells also secrete IFN-? upon stimulation with a superagonistic anti-CD28 monoclonal antibody (CD28-SA). Crosslinking of the CD28-SA via FcR and CD40-CD40L interactions greatly increased IFN-? release. Our data stress the utility of the mouse as a model organism for immune responses in humans.}, author = {Haack, Stephanie and Baiker, Sarah and Schlegel, Jan and Sauer, Markus and Sparwasser, Tim and Langenhorst, Daniela and Beyersdorf, Niklas}, booktitle = {European Journal of Immunology}, journal = {European Journal of Immunology}, keywords = {sauer}, month = {mar}, number = 3, pages = {738–741}, publisher = {John Wiley & Sons, Ltd}, title = {Superagonistic CD28 stimulation induces IFN-γ release from mouse T helper 1 cells in vitro and in vivo}, volume = 51, year = 2021 }

%0 Journal Article %1 haack2021superagonistic %A Haack, Stephanie %A Baiker, Sarah %A Schlegel, Jan %A Sauer, Markus %A Sparwasser, Tim %A Langenhorst, Daniela %A Beyersdorf, Niklas %B European Journal of Immunology %D 2021 %I John Wiley & Sons, Ltd %J European Journal of Immunology %N 3 %P 738--741 %R https://doi.org/10.1002/eji.202048803 %T Superagonistic CD28 stimulation induces IFN-γ release from mouse T helper 1 cells in vitro and in vivo %U https://doi.org/10.1002/eji.202048803 %V 51 %X Like human Th1 cells, mouse Th1 cells also secrete IFN-? upon stimulation with a superagonistic anti-CD28 monoclonal antibody (CD28-SA). Crosslinking of the CD28-SA via FcR and CD40-CD40L interactions greatly increased IFN-? release. Our data stress the utility of the mouse as a model organism for immune responses in humans.
Superresolution Microscopy of Sphingolipids Schlegel, Jan; Sauer, Markus in Lipid Rafts: Methods and Protocols (2021). 303–311.
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This chapter provides a step-by-step protocol to label and visualize sphingolipids by superresolution microscopy with a special focus on single-molecule localization microscopy by dSTORM. We provide information on custom fluorophore conjugation to raft-associated toxins and antibodies, and a labeling protocol for appropriate sample treatment.

@inbook{schlegel2021superresolution, abstract = {This chapter provides a step-by-step protocol to label and visualize sphingolipids by superresolution microscopy with a special focus on single-molecule localization microscopy by dSTORM. We provide information on custom fluorophore conjugation to raft-associated toxins and antibodies, and a labeling protocol for appropriate sample treatment.}, address = {New York, NY}, author = {Schlegel, Jan and Sauer, Markus}, booktitle = {Lipid Rafts: Methods and Protocols}, keywords = {sauer}, pages = {303–311}, publisher = {Springer US}, title = {Superresolution Microscopy of Sphingolipids}, year = 2021 }

%0 Book Section %1 schlegel2021superresolution %A Schlegel, Jan %A Sauer, Markus %B Lipid Rafts: Methods and Protocols %C New York, NY %D 2021 %I Springer US %P 303--311 %R 10.1007/978-1-0716-0814-2_17 %T Superresolution Microscopy of Sphingolipids %U https://doi.org/10.1007/978-1-0716-0814-2_17 %X This chapter provides a step-by-step protocol to label and visualize sphingolipids by superresolution microscopy with a special focus on single-molecule localization microscopy by dSTORM. We provide information on custom fluorophore conjugation to raft-associated toxins and antibodies, and a labeling protocol for appropriate sample treatment. %@ 9781071608142
Photoblueing of organic dyes can cause artifacts in super-resolution microscopy Helmerich, Dominic A.; Beliu, Gerti; Matikonda, Siddharth S.; Schnermann, Martin J.; Sauer, Markus in Nature Methods (2021). 18(3) 253–257.
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Illumination of fluorophores can induce a loss of the ability to fluoresce, known as photobleaching. Interestingly, some fluorophores photoconvert to a blue-shifted fluorescent molecule as an intermediate on the photobleaching pathway, which can complicate multicolor fluorescence imaging, especially under the intense laser irradiation used in super-resolution fluorescence imaging. Here, we discuss the mechanisms of photoblueing of fluorophores and its impact on fluorescence imaging, and show how it can be prevented.

@article{helmerich2021photoblueing, abstract = {Illumination of fluorophores can induce a loss of the ability to fluoresce, known as photobleaching. Interestingly, some fluorophores photoconvert to a blue-shifted fluorescent molecule as an intermediate on the photobleaching pathway, which can complicate multicolor fluorescence imaging, especially under the intense laser irradiation used in super-resolution fluorescence imaging. Here, we discuss the mechanisms of photoblueing of fluorophores and its impact on fluorescence imaging, and show how it can be prevented.}, author = {Helmerich, Dominic A. and Beliu, Gerti and Matikonda, Siddharth S. and Schnermann, Martin J. and Sauer, Markus}, journal = {Nature Methods}, keywords = {sauer}, number = 3, pages = {253–257}, title = {Photoblueing of organic dyes can cause artifacts in super-resolution microscopy}, volume = 18, year = 2021 }

%0 Journal Article %1 helmerich2021photoblueing %A Helmerich, Dominic A. %A Beliu, Gerti %A Matikonda, Siddharth S. %A Schnermann, Martin J. %A Sauer, Markus %D 2021 %J Nature Methods %N 3 %P 253--257 %R 10.1038/s41592-021-01061-2 %T Photoblueing of organic dyes can cause artifacts in super-resolution microscopy %U https://doi.org/10.1038/s41592-021-01061-2 %V 18 %X Illumination of fluorophores can induce a loss of the ability to fluoresce, known as photobleaching. Interestingly, some fluorophores photoconvert to a blue-shifted fluorescent molecule as an intermediate on the photobleaching pathway, which can complicate multicolor fluorescence imaging, especially under the intense laser irradiation used in super-resolution fluorescence imaging. Here, we discuss the mechanisms of photoblueing of fluorophores and its impact on fluorescence imaging, and show how it can be prevented.
Superaufgelöste Mikroskopie: Pilze unter Beobachtung Sputh, Sebastian; Panzer, Sabine; Stigloher, Christian; Terpitz, Ulrich in BIOspektrum (2021). 27(4) 380–382.
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The diffraction limit of light confines fluorescence imaging of subcellular structures in fungi. Different super-resolution methods are available for the analysis of fungi that we briefly discuss. We exploit the filamentous fungus Fusarium fujikuroi expressing a YFP-labeled membrane protein showing the benefit of correlative light- and electron microscopy (CLEM), that combines structured illumination microscopy (SIM) and scanning election microscopy (SEM).

@article{sputh2021superaufgelste, abstract = {The diffraction limit of light confines fluorescence imaging of subcellular structures in fungi. Different super-resolution methods are available for the analysis of fungi that we briefly discuss. We exploit the filamentous fungus Fusarium fujikuroi expressing a YFP-labeled membrane protein showing the benefit of correlative light- and electron microscopy (CLEM), that combines structured illumination microscopy (SIM) and scanning election microscopy (SEM).}, author = {Sputh, Sebastian and Panzer, Sabine and Stigloher, Christian and Terpitz, Ulrich}, journal = {BIOspektrum}, keywords = {terpitz}, number = 4, pages = {380–382}, title = {Superaufgelöste Mikroskopie: Pilze unter Beobachtung}, volume = 27, year = 2021 }

%0 Journal Article %1 sputh2021superaufgelste %A Sputh, Sebastian %A Panzer, Sabine %A Stigloher, Christian %A Terpitz, Ulrich %D 2021 %J BIOspektrum %N 4 %P 380--382 %R 10.1007/s12268-021-1592-6 %T Superaufgelöste Mikroskopie: Pilze unter Beobachtung %U https://doi.org/10.1007/s12268-021-1592-6 %V 27 %X The diffraction limit of light confines fluorescence imaging of subcellular structures in fungi. Different super-resolution methods are available for the analysis of fungi that we briefly discuss. We exploit the filamentous fungus Fusarium fujikuroi expressing a YFP-labeled membrane protein showing the benefit of correlative light- and electron microscopy (CLEM), that combines structured illumination microscopy (SIM) and scanning election microscopy (SEM).

2020[ to top ]

‘Live and Large’: Super-Resolution Optical Fluctuation Imaging (SOFI) and Expansion Microscopy (ExM) of Microtubule Remodelling by Rabies Virus P Protein Rozario, Ashley M.; Zwettler, Fabian; Duwé, Sam; Hargreaves, Riley B.; Brice, Aaron; Dedecker, Peter; Sauer, Markus; Moseley, Gregory W.; Whelan, Donna R.; Bell, Toby D. M. in Aust. J. Chem. (2020).
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The field of super-resolution microscopy continues to progress rapidly, both in terms of evolving techniques and methodologies as well as in the development of new multi-disciplinary applications. Two current drivers of innovation are increasing the possible resolution gain and application in live samples. Super-resolution optical fluctuation imaging (SOFI) is well suited to live samples while expansion microscopy (ExM) enables obtainment of sub-diffraction information via conventional imaging. In this Highlight we provide a brief outline of these methods and report results from application of SOFI and ExM in our on-going study into microtubule remodelling by rabies virus P proteins. We show that MT bundles in live cells transfected with rabies virus P3 protein can be visualised using SOFI in a time-lapse fashion for up to half an hour and can be expanded using current Pro-ExM protocols and imaged using conventional microscopy.

@article{rozario2020large, abstract = {The field of super-resolution microscopy continues to progress rapidly, both in terms of evolving techniques and methodologies as well as in the development of new multi-disciplinary applications. Two current drivers of innovation are increasing the possible resolution gain and application in live samples. Super-resolution optical fluctuation imaging (SOFI) is well suited to live samples while expansion microscopy (ExM) enables obtainment of sub-diffraction information via conventional imaging. In this Highlight we provide a brief outline of these methods and report results from application of SOFI and ExM in our on-going study into microtubule remodelling by rabies virus P proteins. We show that MT bundles in live cells transfected with rabies virus P3 protein can be visualised using SOFI in a time-lapse fashion for up to half an hour and can be expanded using current Pro-ExM protocols and imaged using conventional microscopy.}, author = {Rozario, Ashley M. and Zwettler, Fabian and Duwé, Sam and Hargreaves, Riley B. and Brice, Aaron and Dedecker, Peter and Sauer, Markus and Moseley, Gregory W. and Whelan, Donna R. and Bell, Toby D. M.}, journal = {Aust. J. Chem.}, keywords = {sauer}, title = {‘Live and Large’: Super-Resolution Optical Fluctuation Imaging (SOFI) and Expansion Microscopy (ExM) of Microtubule Remodelling by Rabies Virus P Protein}, year = 2020 }

%0 Journal Article %1 rozario2020large %A Rozario, Ashley M. %A Zwettler, Fabian %A Duwé, Sam %A Hargreaves, Riley B. %A Brice, Aaron %A Dedecker, Peter %A Sauer, Markus %A Moseley, Gregory W. %A Whelan, Donna R. %A Bell, Toby D. M. %D 2020 %J Aust. J. Chem. %T ‘Live and Large’: Super-Resolution Optical Fluctuation Imaging (SOFI) and Expansion Microscopy (ExM) of Microtubule Remodelling by Rabies Virus P Protein %U https://doi.org/10.1071/CH19571 %X The field of super-resolution microscopy continues to progress rapidly, both in terms of evolving techniques and methodologies as well as in the development of new multi-disciplinary applications. Two current drivers of innovation are increasing the possible resolution gain and application in live samples. Super-resolution optical fluctuation imaging (SOFI) is well suited to live samples while expansion microscopy (ExM) enables obtainment of sub-diffraction information via conventional imaging. In this Highlight we provide a brief outline of these methods and report results from application of SOFI and ExM in our on-going study into microtubule remodelling by rabies virus P proteins. We show that MT bundles in live cells transfected with rabies virus P3 protein can be visualised using SOFI in a time-lapse fashion for up to half an hour and can be expanded using current Pro-ExM protocols and imaged using conventional microscopy.
Nanoscale imaging of bacterial infections by sphingolipid expansion microscopy Götz, Ralph; Kunz, Tobias C.; Fink, Julian; Solger, Franziska; Schlegel, Jan; Seibel, Jürgen; Kozjak-Pavlovic, Vera; Rudel, Thomas; Sauer, Markus in Nature Communications (2020). 11(1) 6173-.
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Expansion microscopy (ExM) enables super-resolution imaging of proteins and nucleic acids on conventional microscopes. However, imaging of details of the organization of lipid bilayers by light microscopy remains challenging. We introduce an unnatural short-chain azide- and amino-modified sphingolipid ceramide, which upon incorporation into membranes can be labeled by click chemistry and linked into hydrogels, followed by 4× to 10× expansion. Confocal and structured illumination microscopy (SIM) enable imaging of sphingolipids and their interactions with proteins in the plasma membrane and membrane of intracellular organelles with a spatial resolution of 10–20 nm. As our functionalized sphingolipids accumulate efficiently in pathogens, we use sphingolipid ExM to investigate bacterial infections of human HeLa229 cells by Neisseria gonorrhoeae, Chlamydia trachomatis and Simkania negevensis with a resolution so far only provided by electron microscopy. In particular, sphingolipid ExM allows us to visualize the inner and outer membrane of intracellular bacteria and determine their distance to 27.6 ± 7.7 nm.

@article{gotz2020nanoscale, abstract = {Expansion microscopy (ExM) enables super-resolution imaging of proteins and nucleic acids on conventional microscopes. However, imaging of details of the organization of lipid bilayers by light microscopy remains challenging. We introduce an unnatural short-chain azide- and amino-modified sphingolipid ceramide, which upon incorporation into membranes can be labeled by click chemistry and linked into hydrogels, followed by 4× to 10× expansion. Confocal and structured illumination microscopy (SIM) enable imaging of sphingolipids and their interactions with proteins in the plasma membrane and membrane of intracellular organelles with a spatial resolution of 10–20 nm. As our functionalized sphingolipids accumulate efficiently in pathogens, we use sphingolipid ExM to investigate bacterial infections of human HeLa229 cells by Neisseria gonorrhoeae, Chlamydia trachomatis and Simkania negevensis with a resolution so far only provided by electron microscopy. In particular, sphingolipid ExM allows us to visualize the inner and outer membrane of intracellular bacteria and determine their distance to 27.6 ± 7.7 nm.}, author = {Götz, Ralph and Kunz, Tobias C. and Fink, Julian and Solger, Franziska and Schlegel, Jan and Seibel, Jürgen and Kozjak-Pavlovic, Vera and Rudel, Thomas and Sauer, Markus}, journal = {Nature Communications}, keywords = {sauer}, number = 1, pages = {6173–}, title = {Nanoscale imaging of bacterial infections by sphingolipid expansion microscopy}, volume = 11, year = 2020 }

%0 Journal Article %1 gotz2020nanoscale %A Götz, Ralph %A Kunz, Tobias C. %A Fink, Julian %A Solger, Franziska %A Schlegel, Jan %A Seibel, Jürgen %A Kozjak-Pavlovic, Vera %A Rudel, Thomas %A Sauer, Markus %D 2020 %J Nature Communications %N 1 %P 6173-- %R 10.1038/s41467-020-19897-1 %T Nanoscale imaging of bacterial infections by sphingolipid expansion microscopy %U https://doi.org/10.1038/s41467-020-19897-1 %V 11 %X Expansion microscopy (ExM) enables super-resolution imaging of proteins and nucleic acids on conventional microscopes. However, imaging of details of the organization of lipid bilayers by light microscopy remains challenging. We introduce an unnatural short-chain azide- and amino-modified sphingolipid ceramide, which upon incorporation into membranes can be labeled by click chemistry and linked into hydrogels, followed by 4× to 10× expansion. Confocal and structured illumination microscopy (SIM) enable imaging of sphingolipids and their interactions with proteins in the plasma membrane and membrane of intracellular organelles with a spatial resolution of 10–20 nm. As our functionalized sphingolipids accumulate efficiently in pathogens, we use sphingolipid ExM to investigate bacterial infections of human HeLa229 cells by Neisseria gonorrhoeae, Chlamydia trachomatis and Simkania negevensis with a resolution so far only provided by electron microscopy. In particular, sphingolipid ExM allows us to visualize the inner and outer membrane of intracellular bacteria and determine their distance to 27.6 ± 7.7 nm.
Reconstituting NK Cells After Allogeneic Stem Cell Transplantation Show Impaired Response to the Fungal Pathogen Aspergillus fumigatus Weiss, Esther; Schlegel, Jan; Terpitz, Ulrich; Weber, Michael; Linde, Jörg; Schmitt, Anna-Lena; Hünniger, Kerstin; Marischen, Lothar; Gamon, Florian; Bauer, Joachim; Löffler, Claudia; Kurzai, Oliver; Morton, Charles Oliver; Sauer, Markus; Einsele, Hermann; Loeffler, Juergen in Frontiers in Immunology (2020). 11
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Delayed natural killer (NK) cell reconstitution after allogeneic stem cell transplantation (alloSCT) is associated with a higher risk of developing invasive aspergillosis. The interaction of NK cells with the human pathogen Aspergillus (A.) fumigatus is mediated by the fungal recognition receptor CD56, which is relocated to the fungal interface after contact. Blocking of CD56 signaling inhibits the fungal mediated chemokine secretion of MIP-1α, MIP-1β, and RANTES and reduces cell activation, indicating a functional role of CD56 in fungal recognition. We collected peripheral blood from recipients of an allograft at defined time points after alloSCT (day 60, 90, 120, 180). NK cells were isolated, directly challenged with live A. fumigatus germ tubes, and cell function was analyzed and compared to healthy age and gender-matched individuals. After alloSCT, NK cells displayed a higher percentage of CD56brightCD16dim cells throughout the time of blood collection. However, CD56 binding and relocalization to the fungal contact side were decreased. We were able to correlate this deficiency to the administration of corticosteroid therapy that further negatively influenced the secretion of MIP-1α, MIP-1β, and RANTES. As a consequence, the treatment of healthy NK cells ex vivo with corticosteroids abrogated chemokine secretion measured by multiplex immunoassay. Furthermore, we analyzed NK cells regarding their actin cytoskeleton by Structured Illumination Microscopy (SIM) and flow cytometry and demonstrate an actin dysfunction of NK cells shown by reduced F-actin content after fungal co-cultivation early after alloSCT. This dysfunction remains until 180 days post-alloSCT, concluding that further actin-dependent cellular processes may be negatively influenced after alloSCT. To investigate the molecular pathomechansism, we compared CD56 receptor mobility on the plasma membrane of healthy and alloSCT primary NK cells by single-molecule tracking. The results were very robust and reproducible between tested conditions which point to a different molecular mechanism and emphasize the importance of proper CD56 mobility.

@article{weiss2020reconstituting, abstract = {Delayed natural killer (NK) cell reconstitution after allogeneic stem cell transplantation (alloSCT) is associated with a higher risk of developing invasive aspergillosis. The interaction of NK cells with the human pathogen Aspergillus (A.) fumigatus is mediated by the fungal recognition receptor CD56, which is relocated to the fungal interface after contact. Blocking of CD56 signaling inhibits the fungal mediated chemokine secretion of MIP-1α, MIP-1β, and RANTES and reduces cell activation, indicating a functional role of CD56 in fungal recognition. We collected peripheral blood from recipients of an allograft at defined time points after alloSCT (day 60, 90, 120, 180). NK cells were isolated, directly challenged with live A. fumigatus germ tubes, and cell function was analyzed and compared to healthy age and gender-matched individuals. After alloSCT, NK cells displayed a higher percentage of CD56brightCD16dim cells throughout the time of blood collection. However, CD56 binding and relocalization to the fungal contact side were decreased. We were able to correlate this deficiency to the administration of corticosteroid therapy that further negatively influenced the secretion of MIP-1α, MIP-1β, and RANTES. As a consequence, the treatment of healthy NK cells ex vivo with corticosteroids abrogated chemokine secretion measured by multiplex immunoassay. Furthermore, we analyzed NK cells regarding their actin cytoskeleton by Structured Illumination Microscopy (SIM) and flow cytometry and demonstrate an actin dysfunction of NK cells shown by reduced F-actin content after fungal co-cultivation early after alloSCT. This dysfunction remains until 180 days post-alloSCT, concluding that further actin-dependent cellular processes may be negatively influenced after alloSCT. To investigate the molecular pathomechansism, we compared CD56 receptor mobility on the plasma membrane of healthy and alloSCT primary NK cells by single-molecule tracking. The results were very robust and reproducible between tested conditions which point to a different molecular mechanism and emphasize the importance of proper CD56 mobility.}, author = {Weiss, Esther and Schlegel, Jan and Terpitz, Ulrich and Weber, Michael and Linde, Jörg and Schmitt, Anna-Lena and Hünniger, Kerstin and Marischen, Lothar and Gamon, Florian and Bauer, Joachim and Löffler, Claudia and Kurzai, Oliver and Morton, Charles Oliver and Sauer, Markus and Einsele, Hermann and Loeffler, Juergen}, journal = {Frontiers in Immunology}, keywords = {terpitz}, series = 2117, title = {Reconstituting NK Cells After Allogeneic Stem Cell Transplantation Show Impaired Response to the Fungal Pathogen Aspergillus fumigatus}, volume = 11, year = 2020 }

%0 Journal Article %1 weiss2020reconstituting %A Weiss, Esther %A Schlegel, Jan %A Terpitz, Ulrich %A Weber, Michael %A Linde, Jörg %A Schmitt, Anna-Lena %A Hünniger, Kerstin %A Marischen, Lothar %A Gamon, Florian %A Bauer, Joachim %A Löffler, Claudia %A Kurzai, Oliver %A Morton, Charles Oliver %A Sauer, Markus %A Einsele, Hermann %A Loeffler, Juergen %B 2117 %D 2020 %J Frontiers in Immunology %T Reconstituting NK Cells After Allogeneic Stem Cell Transplantation Show Impaired Response to the Fungal Pathogen Aspergillus fumigatus %U https://www.frontiersin.org/article/10.3389/fimmu.2020.02117 %V 11 %X Delayed natural killer (NK) cell reconstitution after allogeneic stem cell transplantation (alloSCT) is associated with a higher risk of developing invasive aspergillosis. The interaction of NK cells with the human pathogen Aspergillus (A.) fumigatus is mediated by the fungal recognition receptor CD56, which is relocated to the fungal interface after contact. Blocking of CD56 signaling inhibits the fungal mediated chemokine secretion of MIP-1α, MIP-1β, and RANTES and reduces cell activation, indicating a functional role of CD56 in fungal recognition. We collected peripheral blood from recipients of an allograft at defined time points after alloSCT (day 60, 90, 120, 180). NK cells were isolated, directly challenged with live A. fumigatus germ tubes, and cell function was analyzed and compared to healthy age and gender-matched individuals. After alloSCT, NK cells displayed a higher percentage of CD56brightCD16dim cells throughout the time of blood collection. However, CD56 binding and relocalization to the fungal contact side were decreased. We were able to correlate this deficiency to the administration of corticosteroid therapy that further negatively influenced the secretion of MIP-1α, MIP-1β, and RANTES. As a consequence, the treatment of healthy NK cells ex vivo with corticosteroids abrogated chemokine secretion measured by multiplex immunoassay. Furthermore, we analyzed NK cells regarding their actin cytoskeleton by Structured Illumination Microscopy (SIM) and flow cytometry and demonstrate an actin dysfunction of NK cells shown by reduced F-actin content after fungal co-cultivation early after alloSCT. This dysfunction remains until 180 days post-alloSCT, concluding that further actin-dependent cellular processes may be negatively influenced after alloSCT. To investigate the molecular pathomechansism, we compared CD56 receptor mobility on the plasma membrane of healthy and alloSCT primary NK cells by single-molecule tracking. The results were very robust and reproducible between tested conditions which point to a different molecular mechanism and emphasize the importance of proper CD56 mobility.
NMR assignments of a dynamically perturbed and dimerization inhibited N-terminal domain variant of a spider silk protein from E. australis Goretzki, Benedikt; Heiby, Julia C.; Hacker, Carolin; Neuweiler, Hannes; Hellmich, Ute A. in Biomolecular NMR Assignments (2020). 14(1) 67–71.
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Web spiders use specialized glands to produce silk proteins, so-called spidroins, which assemble into extraordinarily tough silk fibers through tightly regulated phase and structural transitions. A crucial step in the polymerization of spidroins is the pH-triggered assembly of their N-terminal domains (NTDs) into tight dimers. Major ampullate spidroin NTDs contain an unusually high content of the amino acid methionine. We previously showed that the simultaneous mutation of the six hydrophobic core methionine residues to leucine in the NTD of the major ampullate spidroin 1 from Euprosthenops australis, a nursery web spider, yields a protein (L6-NTD) retaining a three-dimensional fold identical to the wildtype (WT) domain, yet with a significantly increased stability. Further, the dynamics of the L6-NTD are significantly reduced and the ability to dimerize is severely impaired compared to the WT domain. These properties lead to significant changes in the NMR spectra between WT and L6-NTD so that the previously available WT-NTD assignments cannot be transferred to the mutant protein. Here, we thus report the de novo NMR backbone and side chain assignments of the major ampullate spidroin 1 L6-NTD variant from E. australis as a prerequisite for obtaining further insights into protein structure and dynamics.

@article{goretzki2020assignments, abstract = {Web spiders use specialized glands to produce silk proteins, so-called spidroins, which assemble into extraordinarily tough silk fibers through tightly regulated phase and structural transitions. A crucial step in the polymerization of spidroins is the pH-triggered assembly of their N-terminal domains (NTDs) into tight dimers. Major ampullate spidroin NTDs contain an unusually high content of the amino acid methionine. We previously showed that the simultaneous mutation of the six hydrophobic core methionine residues to leucine in the NTD of the major ampullate spidroin 1 from Euprosthenops australis, a nursery web spider, yields a protein (L6-NTD) retaining a three-dimensional fold identical to the wildtype (WT) domain, yet with a significantly increased stability. Further, the dynamics of the L6-NTD are significantly reduced and the ability to dimerize is severely impaired compared to the WT domain. These properties lead to significant changes in the NMR spectra between WT and L6-NTD so that the previously available WT-NTD assignments cannot be transferred to the mutant protein. Here, we thus report the de novo NMR backbone and side chain assignments of the major ampullate spidroin 1 L6-NTD variant from E. australis as a prerequisite for obtaining further insights into protein structure and dynamics.}, author = {Goretzki, Benedikt and Heiby, Julia C. and Hacker, Carolin and Neuweiler, Hannes and Hellmich, Ute A.}, journal = {Biomolecular NMR Assignments}, keywords = {hannes}, number = 1, pages = {67–71}, title = {NMR assignments of a dynamically perturbed and dimerization inhibited N-terminal domain variant of a spider silk protein from E. australis}, volume = 14, year = 2020 }

%0 Journal Article %1 goretzki2020assignments %A Goretzki, Benedikt %A Heiby, Julia C. %A Hacker, Carolin %A Neuweiler, Hannes %A Hellmich, Ute A. %D 2020 %J Biomolecular NMR Assignments %N 1 %P 67--71 %R 10.1007/s12104-019-09922-w %T NMR assignments of a dynamically perturbed and dimerization inhibited N-terminal domain variant of a spider silk protein from E. australis %U https://doi.org/10.1007/s12104-019-09922-w %V 14 %X Web spiders use specialized glands to produce silk proteins, so-called spidroins, which assemble into extraordinarily tough silk fibers through tightly regulated phase and structural transitions. A crucial step in the polymerization of spidroins is the pH-triggered assembly of their N-terminal domains (NTDs) into tight dimers. Major ampullate spidroin NTDs contain an unusually high content of the amino acid methionine. We previously showed that the simultaneous mutation of the six hydrophobic core methionine residues to leucine in the NTD of the major ampullate spidroin 1 from Euprosthenops australis, a nursery web spider, yields a protein (L6-NTD) retaining a three-dimensional fold identical to the wildtype (WT) domain, yet with a significantly increased stability. Further, the dynamics of the L6-NTD are significantly reduced and the ability to dimerize is severely impaired compared to the WT domain. These properties lead to significant changes in the NMR spectra between WT and L6-NTD so that the previously available WT-NTD assignments cannot be transferred to the mutant protein. Here, we thus report the de novo NMR backbone and side chain assignments of the major ampullate spidroin 1 L6-NTD variant from E. australis as a prerequisite for obtaining further insights into protein structure and dynamics.
Chapter Ten - Conformationally restrained pentamethine cyanines and use in reductive single molecule localization microscopy Matikonda, Siddharth S.; Götz, Ralph; McLaughlin, Ryan; Sauer, Markus; Schnermann, Martin J. in Chemical Tools for Imaging, Manipulating, and Tracking Biological Systems: Diverse Chemical, Optical and Bioorthogonal Methods, D. M. Chenoweth (Hrsg.) (2020). (Bd. 641) 225–244.
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Pentamethine cyanines are a class of far-red fluorophores that find extensive use in single-molecule localization microscopy (SMLM), as well as a broad range of other techniques. A drawback of this scaffold is its relatively low quantum yields, which is due to excited state deactivation via trans-to-cis chromophore isomerization. Here we describe a synthetic strategy to improve the photon output of these molecules. In the key synthetic transformation, a protected dialdehyde precursor undergoes a cascade reaction that forms a tetracyclic ring system. The resulting conformationally restrained analogs exhibit improved fluorescence quantum yield and extended fluorescence lifetimes. These properties, together with their ability to efficiently recover from hydride reduction, enable a uniquely simple form of single-molecule localization microscopy (SMLM).

@inbook{matikonda2020chapter, abstract = {Pentamethine cyanines are a class of far-red fluorophores that find extensive use in single-molecule localization microscopy (SMLM), as well as a broad range of other techniques. A drawback of this scaffold is its relatively low quantum yields, which is due to excited state deactivation via trans-to-cis chromophore isomerization. Here we describe a synthetic strategy to improve the photon output of these molecules. In the key synthetic transformation, a protected dialdehyde precursor undergoes a cascade reaction that forms a tetracyclic ring system. The resulting conformationally restrained analogs exhibit improved fluorescence quantum yield and extended fluorescence lifetimes. These properties, together with their ability to efficiently recover from hydride reduction, enable a uniquely simple form of single-molecule localization microscopy (SMLM).}, author = {Matikonda, Siddharth S. and Götz, Ralph and McLaughlin, Ryan and Sauer, Markus and Schnermann, Martin J.}, booktitle = {Chemical Tools for Imaging, Manipulating, and Tracking Biological Systems: Diverse Chemical, Optical and Bioorthogonal Methods}, editor = {Chenoweth, David M.}, keywords = {sauer}, pages = {225–244}, publisher = {Academic Press}, title = {Chapter Ten - Conformationally restrained pentamethine cyanines and use in reductive single molecule localization microscopy}, volume = 641, year = 2020 }

%0 Book Section %1 matikonda2020chapter %A Matikonda, Siddharth S. %A Götz, Ralph %A McLaughlin, Ryan %A Sauer, Markus %A Schnermann, Martin J. %B Chemical Tools for Imaging, Manipulating, and Tracking Biological Systems: Diverse Chemical, Optical and Bioorthogonal Methods %D 2020 %E Chenoweth, David M. %I Academic Press %P 225--244 %R https://doi.org/10.1016/bs.mie.2020.04.042 %T Chapter Ten - Conformationally restrained pentamethine cyanines and use in reductive single molecule localization microscopy %U https://www.sciencedirect.com/science/article/pii/S0076687920301701 %V 641 %X Pentamethine cyanines are a class of far-red fluorophores that find extensive use in single-molecule localization microscopy (SMLM), as well as a broad range of other techniques. A drawback of this scaffold is its relatively low quantum yields, which is due to excited state deactivation via trans-to-cis chromophore isomerization. Here we describe a synthetic strategy to improve the photon output of these molecules. In the key synthetic transformation, a protected dialdehyde precursor undergoes a cascade reaction that forms a tetracyclic ring system. The resulting conformationally restrained analogs exhibit improved fluorescence quantum yield and extended fluorescence lifetimes. These properties, together with their ability to efficiently recover from hydride reduction, enable a uniquely simple form of single-molecule localization microscopy (SMLM).
Variant signaling topology at the cancer cell–T-cell interface induced by a two-component T-cell engager Kouhestani, Dina; Geis, Maria; Alsouri, Saed; Bumm, Thomas G. P.; Einsele, Hermann; Sauer, Markus; Stuhler, Gernot in Cellular & Molecular Immunology (2020).
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@article{kouhestani2020variant, author = {Kouhestani, Dina and Geis, Maria and Alsouri, Saed and Bumm, Thomas G. P. and Einsele, Hermann and Sauer, Markus and Stuhler, Gernot}, journal = {Cellular & Molecular Immunology}, keywords = {sauer}, title = {Variant signaling topology at the cancer cell–T-cell interface induced by a two-component T-cell engager}, year = 2020 }

%0 Journal Article %1 kouhestani2020variant %A Kouhestani, Dina %A Geis, Maria %A Alsouri, Saed %A Bumm, Thomas G. P. %A Einsele, Hermann %A Sauer, Markus %A Stuhler, Gernot %D 2020 %J Cellular & Molecular Immunology %R 10.1038/s41423-020-0507-7 %T Variant signaling topology at the cancer cell–T-cell interface induced by a two-component T-cell engager %U https://doi.org/10.1038/s41423-020-0507-7
BIN2 orchestrates platelet calcium signaling in thrombosis and thrombo-inflammation Volz, Julia; Kusch, Charly; Beck, Sarah; Popp, Michael; Vögtle, Timo; Meub, Mara; Scheller, Inga; Heil, Hannah S.; Preu, Julia; Schuhmann, Michael K.; Hemmen, Katherina; Premsler, Thomas; Sickmann, Albert; Heinze, Katrin G.; Stegner, David; Stoll, Guido; Braun, Attila; Sauer, Markus; Nieswandt, Bernhard in The Journal of Clinical Investigation (2020). 130(11) 6064–6079.
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Store-operated Ca2+ entry (SOCE) is the major route of Ca2+ influx in platelets. The Ca2+ sensor stromal interaction molecule 1 (STIM1) triggers SOCE by forming punctate structures with the Ca2+ channel Orai1 and the inositol trisphosphate receptor (IP3R), thereby linking the endo-/sarcoplasmic reticulum to the plasma membrane. Here, we identified the BAR domain superfamily member bridging integrator 2 (BIN2) as an interaction partner of STIM1 and IP3R in platelets. Deletion of platelet BIN2 (Bin2fl/fl,Pf4-Cre mice) resulted in reduced Ca2+ store release and Ca2+ influx in response to all tested platelet agonists. These defects were a consequence of impaired IP3R function in combination with defective STIM1-mediated SOC channel activation, while Ca2+ store content and agonist-induced IP3 production were unaltered. This severely defective Ca2+ signaling translated into impaired thrombus formation under flow and a protection of Bin2fl/fl,Pf4-Cre mice in models of arterial thrombosis and stroke. Our results establish BIN2 as a central regulator of platelet activation in thrombosis and thrombo-inflammatory disease settings.

@article{volz2020orchestrates, abstract = {Store-operated Ca2+ entry (SOCE) is the major route of Ca2+ influx in platelets. The Ca2+ sensor stromal interaction molecule 1 (STIM1) triggers SOCE by forming punctate structures with the Ca2+ channel Orai1 and the inositol trisphosphate receptor (IP3R), thereby linking the endo-/sarcoplasmic reticulum to the plasma membrane. Here, we identified the BAR domain superfamily member bridging integrator 2 (BIN2) as an interaction partner of STIM1 and IP3R in platelets. Deletion of platelet BIN2 (Bin2fl/fl,Pf4-Cre mice) resulted in reduced Ca2+ store release and Ca2+ influx in response to all tested platelet agonists. These defects were a consequence of impaired IP3R function in combination with defective STIM1-mediated SOC channel activation, while Ca2+ store content and agonist-induced IP3 production were unaltered. This severely defective Ca2+ signaling translated into impaired thrombus formation under flow and a protection of Bin2fl/fl,Pf4-Cre mice in models of arterial thrombosis and stroke. Our results establish BIN2 as a central regulator of platelet activation in thrombosis and thrombo-inflammatory disease settings.}, author = {Volz, Julia and Kusch, Charly and Beck, Sarah and Popp, Michael and Vögtle, Timo and Meub, Mara and Scheller, Inga and Heil, Hannah S. and Preu, Julia and Schuhmann, Michael K. and Hemmen, Katherina and Premsler, Thomas and Sickmann, Albert and Heinze, Katrin G. and Stegner, David and Stoll, Guido and Braun, Attila and Sauer, Markus and Nieswandt, Bernhard}, journal = {The Journal of Clinical Investigation}, keywords = {sauer}, month = {nov}, number = 11, pages = {6064–6079}, publisher = {The American Society for Clinical Investigation}, title = {BIN2 orchestrates platelet calcium signaling in thrombosis and thrombo-inflammation}, volume = 130, year = 2020 }

%0 Journal Article %1 volz2020orchestrates %A Volz, Julia %A Kusch, Charly %A Beck, Sarah %A Popp, Michael %A Vögtle, Timo %A Meub, Mara %A Scheller, Inga %A Heil, Hannah S. %A Preu, Julia %A Schuhmann, Michael K. %A Hemmen, Katherina %A Premsler, Thomas %A Sickmann, Albert %A Heinze, Katrin G. %A Stegner, David %A Stoll, Guido %A Braun, Attila %A Sauer, Markus %A Nieswandt, Bernhard %D 2020 %I The American Society for Clinical Investigation %J The Journal of Clinical Investigation %N 11 %P 6064--6079 %R 10.1172/JCI136457 %T BIN2 orchestrates platelet calcium signaling in thrombosis and thrombo-inflammation %U https://doi.org/10.1172/JCI136457 %V 130 %X Store-operated Ca2+ entry (SOCE) is the major route of Ca2+ influx in platelets. The Ca2+ sensor stromal interaction molecule 1 (STIM1) triggers SOCE by forming punctate structures with the Ca2+ channel Orai1 and the inositol trisphosphate receptor (IP3R), thereby linking the endo-/sarcoplasmic reticulum to the plasma membrane. Here, we identified the BAR domain superfamily member bridging integrator 2 (BIN2) as an interaction partner of STIM1 and IP3R in platelets. Deletion of platelet BIN2 (Bin2fl/fl,Pf4-Cre mice) resulted in reduced Ca2+ store release and Ca2+ influx in response to all tested platelet agonists. These defects were a consequence of impaired IP3R function in combination with defective STIM1-mediated SOC channel activation, while Ca2+ store content and agonist-induced IP3 production were unaltered. This severely defective Ca2+ signaling translated into impaired thrombus formation under flow and a protection of Bin2fl/fl,Pf4-Cre mice in models of arterial thrombosis and stroke. Our results establish BIN2 as a central regulator of platelet activation in thrombosis and thrombo-inflammatory disease settings.
Induction of BDNF Expression in Layer II/III and Layer V Neurons of the Motor Cortex Is Essential for Motor Learning Andreska, Thomas; Rauskolb, Stefanie; Schukraft, Nina; Lüningschrör, Patrick; Sasi, Manju; Signoret-Genest, Jeremy; Behringer, Marcus; Blum, Robert; Sauer, Markus; Tovote, Philip; Sendtner, Michael in J. Neurosci. (2020). 40(33) 6289-.
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Motor learning depends on synaptic plasticity between corticostriatal projections and striatal medium spiny neurons. Retrograde tracing from the dorsolateral striatum reveals that both layer II/III and V neurons in the motor cortex express BDNF as a potential regulator of plasticity in corticostriatal projections in male and female mice. The number of these BDNF-expressing cortical neurons and levels of BDNF protein are highest in juvenile mice when adult motor patterns are shaped, while BDNF levels in the adult are low. When mice are trained by physical exercise in the adult, BDNF expression in motor cortex is reinduced, especially in layer II/III projection neurons. Reduced expression of cortical BDNF in 3-month-old mice results in impaired motor learning while space memory is preserved. These findings suggest that activity regulates BDNF expression differentially in layers II/III and V striatal afferents from motor cortex and that cortical BDNF is essential for motor learning.SIGNIFICANCE STATEMENT Motor learning in mice depends on corticostriatal BDNF supply, and regulation of BDNF expression during motor learning is highest in corticostriatal projection neurons in cortical layer II/III.

@article{andreska2020induction, abstract = {Motor learning depends on synaptic plasticity between corticostriatal projections and striatal medium spiny neurons. Retrograde tracing from the dorsolateral striatum reveals that both layer II/III and V neurons in the motor cortex express BDNF as a potential regulator of plasticity in corticostriatal projections in male and female mice. The number of these BDNF-expressing cortical neurons and levels of BDNF protein are highest in juvenile mice when adult motor patterns are shaped, while BDNF levels in the adult are low. When mice are trained by physical exercise in the adult, BDNF expression in motor cortex is reinduced, especially in layer II/III projection neurons. Reduced expression of cortical BDNF in 3-month-old mice results in impaired motor learning while space memory is preserved. These findings suggest that activity regulates BDNF expression differentially in layers II/III and V striatal afferents from motor cortex and that cortical BDNF is essential for motor learning.SIGNIFICANCE STATEMENT Motor learning in mice depends on corticostriatal BDNF supply, and regulation of BDNF expression during motor learning is highest in corticostriatal projection neurons in cortical layer II/III.}, author = {Andreska, Thomas and Rauskolb, Stefanie and Schukraft, Nina and Lüningschrör, Patrick and Sasi, Manju and Signoret-Genest, Jeremy and Behringer, Marcus and Blum, Robert and Sauer, Markus and Tovote, Philip and Sendtner, Michael}, journal = {J. Neurosci.}, keywords = {sauer}, month = {aug}, number = 33, pages = {6289–}, title = {Induction of BDNF Expression in Layer II/III and Layer V Neurons of the Motor Cortex Is Essential for Motor Learning}, volume = 40, year = 2020 }

%0 Journal Article %1 andreska2020induction %A Andreska, Thomas %A Rauskolb, Stefanie %A Schukraft, Nina %A Lüningschrör, Patrick %A Sasi, Manju %A Signoret-Genest, Jeremy %A Behringer, Marcus %A Blum, Robert %A Sauer, Markus %A Tovote, Philip %A Sendtner, Michael %D 2020 %J J. Neurosci. %N 33 %P 6289-- %R 10.1523/JNEUROSCI.0288-20.2020 %T Induction of BDNF Expression in Layer II/III and Layer V Neurons of the Motor Cortex Is Essential for Motor Learning %U http://www.jneurosci.org/content/40/33/6289.abstract %V 40 %X Motor learning depends on synaptic plasticity between corticostriatal projections and striatal medium spiny neurons. Retrograde tracing from the dorsolateral striatum reveals that both layer II/III and V neurons in the motor cortex express BDNF as a potential regulator of plasticity in corticostriatal projections in male and female mice. The number of these BDNF-expressing cortical neurons and levels of BDNF protein are highest in juvenile mice when adult motor patterns are shaped, while BDNF levels in the adult are low. When mice are trained by physical exercise in the adult, BDNF expression in motor cortex is reinduced, especially in layer II/III projection neurons. Reduced expression of cortical BDNF in 3-month-old mice results in impaired motor learning while space memory is preserved. These findings suggest that activity regulates BDNF expression differentially in layers II/III and V striatal afferents from motor cortex and that cortical BDNF is essential for motor learning.SIGNIFICANCE STATEMENT Motor learning in mice depends on corticostriatal BDNF supply, and regulation of BDNF expression during motor learning is highest in corticostriatal projection neurons in cortical layer II/III.
Serotonin (5-HT) neuron-specific inactivation of Cadherin-13 impacts 5-HT system formation and cognitive function Forero, Andrea; Ku, Hsing-Ping; Malpartida, Ana Belén; Wäldchen, Sina; Alhama-Riba, Judit; Kulka, Christina; Aboagye, Benjamin; Norton, William H.J; Young, Andrew M.J; Ding, Yu-Qiang; Blum, Robert; Sauer, Markus; Rivero, Olga; Lesch, Klaus-Peter in Neuropharmacology (2020). 168 108018-.
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Genome-wide screening approaches identified the cell adhesion molecule Cadherin-13 (CDH13) as a risk factor for neurodevelopmental disorders, nevertheless the contribution of CDH13 to the disease mechanism remains obscure. CDH13 is involved in neurite outgrowth and axon guidance during early brain development and we previously provided evidence that constitutive CDH13 deficiency influences the formation of the raphe serotonin (5-HT) system by modifying neuron-radial glia interaction. Here, we dissect the specific impact of CDH13 on 5-HT system development and function using a 5-HT neuron-specific Cdh13 knockout mouse model (conditional Cdh13 knockout, Cdh13 cKO). Our results show that exclusive inactivation of CDH13 in 5-HT neurons selectively increases 5-HT neuron density in the embryonic dorsal raphe, with persistence into adulthood, and serotonergic innervation of the developing prefrontal cortex. At the behavioral level, adult Cdh13 cKO mice display delayed acquisition of several learning tasks and a subtle impulsive-like phenotype, with decreased latency in a sociability paradigm alongside with deficits in visuospatial memory. Anxiety-related traits were not observed in Cdh13 cKO mice. Our findings further support the critical role of CDH13 in the development of dorsal raphe 5-HT circuitries, a mechanism that may underlie specific clinical features observed in neurodevelopmental disorders.

@article{forero2020serotonin, abstract = {Genome-wide screening approaches identified the cell adhesion molecule Cadherin-13 (CDH13) as a risk factor for neurodevelopmental disorders, nevertheless the contribution of CDH13 to the disease mechanism remains obscure. CDH13 is involved in neurite outgrowth and axon guidance during early brain development and we previously provided evidence that constitutive CDH13 deficiency influences the formation of the raphe serotonin (5-HT) system by modifying neuron-radial glia interaction. Here, we dissect the specific impact of CDH13 on 5-HT system development and function using a 5-HT neuron-specific Cdh13 knockout mouse model (conditional Cdh13 knockout, Cdh13 cKO). Our results show that exclusive inactivation of CDH13 in 5-HT neurons selectively increases 5-HT neuron density in the embryonic dorsal raphe, with persistence into adulthood, and serotonergic innervation of the developing prefrontal cortex. At the behavioral level, adult Cdh13 cKO mice display delayed acquisition of several learning tasks and a subtle impulsive-like phenotype, with decreased latency in a sociability paradigm alongside with deficits in visuospatial memory. Anxiety-related traits were not observed in Cdh13 cKO mice. Our findings further support the critical role of CDH13 in the development of dorsal raphe 5-HT circuitries, a mechanism that may underlie specific clinical features observed in neurodevelopmental disorders.}, author = {Forero, Andrea and Ku, Hsing-Ping and Malpartida, Ana Belén and Wäldchen, Sina and Alhama-Riba, Judit and Kulka, Christina and Aboagye, Benjamin and Norton, William H.J and Young, Andrew M.J and Ding, Yu-Qiang and Blum, Robert and Sauer, Markus and Rivero, Olga and Lesch, Klaus-Peter}, journal = {Neuropharmacology}, keywords = {sauer}, pages = {108018–}, title = {Serotonin (5-HT) neuron-specific inactivation of Cadherin-13 impacts 5-HT system formation and cognitive function}, volume = 168, year = 2020 }

%0 Journal Article %1 forero2020serotonin %A Forero, Andrea %A Ku, Hsing-Ping %A Malpartida, Ana Belén %A Wäldchen, Sina %A Alhama-Riba, Judit %A Kulka, Christina %A Aboagye, Benjamin %A Norton, William H.J %A Young, Andrew M.J %A Ding, Yu-Qiang %A Blum, Robert %A Sauer, Markus %A Rivero, Olga %A Lesch, Klaus-Peter %D 2020 %J Neuropharmacology %P 108018-- %R https://doi.org/10.1016/j.neuropharm.2020.108018 %T Serotonin (5-HT) neuron-specific inactivation of Cadherin-13 impacts 5-HT system formation and cognitive function %U https://www.sciencedirect.com/science/article/pii/S0028390820300848 %V 168 %X Genome-wide screening approaches identified the cell adhesion molecule Cadherin-13 (CDH13) as a risk factor for neurodevelopmental disorders, nevertheless the contribution of CDH13 to the disease mechanism remains obscure. CDH13 is involved in neurite outgrowth and axon guidance during early brain development and we previously provided evidence that constitutive CDH13 deficiency influences the formation of the raphe serotonin (5-HT) system by modifying neuron-radial glia interaction. Here, we dissect the specific impact of CDH13 on 5-HT system development and function using a 5-HT neuron-specific Cdh13 knockout mouse model (conditional Cdh13 knockout, Cdh13 cKO). Our results show that exclusive inactivation of CDH13 in 5-HT neurons selectively increases 5-HT neuron density in the embryonic dorsal raphe, with persistence into adulthood, and serotonergic innervation of the developing prefrontal cortex. At the behavioral level, adult Cdh13 cKO mice display delayed acquisition of several learning tasks and a subtle impulsive-like phenotype, with decreased latency in a sociability paradigm alongside with deficits in visuospatial memory. Anxiety-related traits were not observed in Cdh13 cKO mice. Our findings further support the critical role of CDH13 in the development of dorsal raphe 5-HT circuitries, a mechanism that may underlie specific clinical features observed in neurodevelopmental disorders.
Interaction of YAP with the Myb-MuvB (MMB) complex defines a transcriptional program to promote the proliferation of cardiomyocytes Gründl, Marco; Walz, Susanne; Hauf, Laura; Schwab, Melissa; Werner, Kerstin Marcela; Spahr, Susanne; Schulte, Clemens; Maric, Hans Michael; Ade, Carsten P.; Gaubatz, Stefan in PLOS Genetics (2020). 16(5) e1008818-.
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Author summary YAP, the major downstream transducer of the Hippo pathway, is a potent inducer of proliferation. Here we show that the Myb-MuvB complex (MMB) mediates cardiomyocyte proliferation by YAP. We find that YAP and MMB regulate an overlapping set of pro-proliferative genes which involves binding of MMB to the promoters of these genes. We also identified a direct interaction between the B-MYB subunit of MMB and YAP. Based on the binding studies, we created a tool called MY-COMP that interferes with the association YAP to B-MYB and strongly inhibits proliferation of cardiomyocytes. Together, our data suggests that the YAP-MMB interaction is essential for division of cardiomyocytes, underscoring the functional relevance of the crosstalk between these two pathways for proper heart development.

@article{grundl2020interaction, abstract = {Author summary YAP, the major downstream transducer of the Hippo pathway, is a potent inducer of proliferation. Here we show that the Myb-MuvB complex (MMB) mediates cardiomyocyte proliferation by YAP. We find that YAP and MMB regulate an overlapping set of pro-proliferative genes which involves binding of MMB to the promoters of these genes. We also identified a direct interaction between the B-MYB subunit of MMB and YAP. Based on the binding studies, we created a tool called MY-COMP that interferes with the association YAP to B-MYB and strongly inhibits proliferation of cardiomyocytes. Together, our data suggests that the YAP-MMB interaction is essential for division of cardiomyocytes, underscoring the functional relevance of the crosstalk between these two pathways for proper heart development.}, author = {Gründl, Marco and Walz, Susanne and Hauf, Laura and Schwab, Melissa and Werner, Kerstin Marcela and Spahr, Susanne and Schulte, Clemens and Maric, Hans Michael and Ade, Carsten P. and Gaubatz, Stefan}, journal = {PLOS Genetics}, keywords = {maric}, month = {may}, number = 5, pages = {e1008818–}, publisher = {Public Library of Science}, title = {Interaction of YAP with the Myb-MuvB (MMB) complex defines a transcriptional program to promote the proliferation of cardiomyocytes}, volume = 16, year = 2020 }

%0 Journal Article %1 grundl2020interaction %A Gründl, Marco %A Walz, Susanne %A Hauf, Laura %A Schwab, Melissa %A Werner, Kerstin Marcela %A Spahr, Susanne %A Schulte, Clemens %A Maric, Hans Michael %A Ade, Carsten P. %A Gaubatz, Stefan %D 2020 %I Public Library of Science %J PLOS Genetics %N 5 %P e1008818-- %T Interaction of YAP with the Myb-MuvB (MMB) complex defines a transcriptional program to promote the proliferation of cardiomyocytes %U https://doi.org/10.1371/journal.pgen.1008818 %V 16 %X Author summary YAP, the major downstream transducer of the Hippo pathway, is a potent inducer of proliferation. Here we show that the Myb-MuvB complex (MMB) mediates cardiomyocyte proliferation by YAP. We find that YAP and MMB regulate an overlapping set of pro-proliferative genes which involves binding of MMB to the promoters of these genes. We also identified a direct interaction between the B-MYB subunit of MMB and YAP. Based on the binding studies, we created a tool called MY-COMP that interferes with the association YAP to B-MYB and strongly inhibits proliferation of cardiomyocytes. Together, our data suggests that the YAP-MMB interaction is essential for division of cardiomyocytes, underscoring the functional relevance of the crosstalk between these two pathways for proper heart development.
Multiple-Labeled Antibodies Behave Like Single Emitters in Photoswitching Buffer Helmerich, Dominic A.; Beliu, Gerti; Sauer, Markus in ACS Nano (2020).
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The degree of labeling (DOL) of antibodies has so far been optimized for high brightness and specific and efficient binding. The influence of the DOL on the blinking performance of antibodies used in direct stochastic optical reconstruction microscopy (dSTORM) has so far attained limited attention. Here, we investigated the spectroscopic characteristics of IgG antibodies labeled at DOLs of 1.1–8.3 with Alexa Fluor 647 (Al647) at the ensemble and single-molecule level. Multiple-Al647-labeled antibodies showed weak and strong quenching interactions in aqueous buffer but could all be used for dSTORM imaging with spatial resolutions of ∼20 nm independent of the DOL. Single-molecule fluorescence trajectories and photon antibunching experiments revealed that individual multiple-Al647-labeled antibodies show complex photophysics in aqueous buffer but behave as single emitters in photoswitching buffer independent of the DOL. We developed a model that explains the observed blinking of multiple-labeled antibodies and can be used for the development of improved fluorescent probes for dSTORM experiments.

@article{helmerich2020multiplelabeled, abstract = {The degree of labeling (DOL) of antibodies has so far been optimized for high brightness and specific and efficient binding. The influence of the DOL on the blinking performance of antibodies used in direct stochastic optical reconstruction microscopy (dSTORM) has so far attained limited attention. Here, we investigated the spectroscopic characteristics of IgG antibodies labeled at DOLs of 1.1–8.3 with Alexa Fluor 647 (Al647) at the ensemble and single-molecule level. Multiple-Al647-labeled antibodies showed weak and strong quenching interactions in aqueous buffer but could all be used for dSTORM imaging with spatial resolutions of ∼20 nm independent of the DOL. Single-molecule fluorescence trajectories and photon antibunching experiments revealed that individual multiple-Al647-labeled antibodies show complex photophysics in aqueous buffer but behave as single emitters in photoswitching buffer independent of the DOL. We developed a model that explains the observed blinking of multiple-labeled antibodies and can be used for the development of improved fluorescent probes for dSTORM experiments.}, author = {Helmerich, Dominic A. and Beliu, Gerti and Sauer, Markus}, booktitle = {ACS Nano}, journal = {ACS Nano}, keywords = {sauer}, month = {aug}, publisher = {American Chemical Society}, title = {Multiple-Labeled Antibodies Behave Like Single Emitters in Photoswitching Buffer}, year = 2020 }

%0 Journal Article %1 helmerich2020multiplelabeled %A Helmerich, Dominic A. %A Beliu, Gerti %A Sauer, Markus %B ACS Nano %D 2020 %I American Chemical Society %J ACS Nano %R 10.1021/acsnano.0c06099 %T Multiple-Labeled Antibodies Behave Like Single Emitters in Photoswitching Buffer %U https://doi.org/10.1021/acsnano.0c06099 %X The degree of labeling (DOL) of antibodies has so far been optimized for high brightness and specific and efficient binding. The influence of the DOL on the blinking performance of antibodies used in direct stochastic optical reconstruction microscopy (dSTORM) has so far attained limited attention. Here, we investigated the spectroscopic characteristics of IgG antibodies labeled at DOLs of 1.1–8.3 with Alexa Fluor 647 (Al647) at the ensemble and single-molecule level. Multiple-Al647-labeled antibodies showed weak and strong quenching interactions in aqueous buffer but could all be used for dSTORM imaging with spatial resolutions of ∼20 nm independent of the DOL. Single-molecule fluorescence trajectories and photon antibunching experiments revealed that individual multiple-Al647-labeled antibodies show complex photophysics in aqueous buffer but behave as single emitters in photoswitching buffer independent of the DOL. We developed a model that explains the observed blinking of multiple-labeled antibodies and can be used for the development of improved fluorescent probes for dSTORM experiments.
Tracking down the molecular architecture of the synaptonemal complex by expansion microscopy Zwettler, Fabian U.; Spindler, Marie-Christin; Reinhard, Sebastian; Klein, Teresa; Kurz, Andreas; Benavente, Ricardo; Sauer, Markus in Nature Communications (2020). 11(1) 3222-.
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The synaptonemal complex (SC) is a meiosis-specific nuclear multiprotein complex that is essential for proper synapsis, recombination and segregation of homologous chromosomes. We combined structured illumination microscopy (SIM) with different expansion microscopy (ExM) protocols including U-ExM, proExM, and magnified analysis of the proteome (MAP) to investigate the molecular organization of the SC. Comparison with structural data obtained by single-molecule localization microscopy of unexpanded SCs allowed us to investigate ultrastructure preservation of expanded SCs. For image analysis, we developed an automatic image processing software that enabled unbiased comparison of structural properties pre- and post-expansion. Here, MAP-SIM provided the best results and enabled reliable three-color super-resolution microscopy of the SCs of a whole set of chromosomes in a spermatocyte with 20–30 nm spatial resolution. Our data demonstrate that post-expansion labeling by MAP-SIM improves immunolabeling efficiency and allowed us thus to unravel previously hidden details of the molecular organization of SCs.

@article{zwettler2020tracking, abstract = {The synaptonemal complex (SC) is a meiosis-specific nuclear multiprotein complex that is essential for proper synapsis, recombination and segregation of homologous chromosomes. We combined structured illumination microscopy (SIM) with different expansion microscopy (ExM) protocols including U-ExM, proExM, and magnified analysis of the proteome (MAP) to investigate the molecular organization of the SC. Comparison with structural data obtained by single-molecule localization microscopy of unexpanded SCs allowed us to investigate ultrastructure preservation of expanded SCs. For image analysis, we developed an automatic image processing software that enabled unbiased comparison of structural properties pre- and post-expansion. Here, MAP-SIM provided the best results and enabled reliable three-color super-resolution microscopy of the SCs of a whole set of chromosomes in a spermatocyte with 20–30 nm spatial resolution. Our data demonstrate that post-expansion labeling by MAP-SIM improves immunolabeling efficiency and allowed us thus to unravel previously hidden details of the molecular organization of SCs.}, author = {Zwettler, Fabian U. and Spindler, Marie-Christin and Reinhard, Sebastian and Klein, Teresa and Kurz, Andreas and Benavente, Ricardo and Sauer, Markus}, journal = {Nature Communications}, keywords = {sauer}, number = 1, pages = {3222–}, title = {Tracking down the molecular architecture of the synaptonemal complex by expansion microscopy}, volume = 11, year = 2020 }

%0 Journal Article %1 zwettler2020tracking %A Zwettler, Fabian U. %A Spindler, Marie-Christin %A Reinhard, Sebastian %A Klein, Teresa %A Kurz, Andreas %A Benavente, Ricardo %A Sauer, Markus %D 2020 %J Nature Communications %N 1 %P 3222-- %R 10.1038/s41467-020-17017-7 %T Tracking down the molecular architecture of the synaptonemal complex by expansion microscopy %U https://doi.org/10.1038/s41467-020-17017-7 %V 11 %X The synaptonemal complex (SC) is a meiosis-specific nuclear multiprotein complex that is essential for proper synapsis, recombination and segregation of homologous chromosomes. We combined structured illumination microscopy (SIM) with different expansion microscopy (ExM) protocols including U-ExM, proExM, and magnified analysis of the proteome (MAP) to investigate the molecular organization of the SC. Comparison with structural data obtained by single-molecule localization microscopy of unexpanded SCs allowed us to investigate ultrastructure preservation of expanded SCs. For image analysis, we developed an automatic image processing software that enabled unbiased comparison of structural properties pre- and post-expansion. Here, MAP-SIM provided the best results and enabled reliable three-color super-resolution microscopy of the SCs of a whole set of chromosomes in a spermatocyte with 20–30 nm spatial resolution. Our data demonstrate that post-expansion labeling by MAP-SIM improves immunolabeling efficiency and allowed us thus to unravel previously hidden details of the molecular organization of SCs.
Whole-cell imaging of plasma membrane receptors by 3D lattice light-sheet dSTORM Wäldchen, Felix; Schlegel, Jan; Götz, Ralph; Luciano, Michael; Schnermann, Martin; Doose, Sören; Sauer, Markus in Nature Communications (2020). 11(1) 887-.
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The molecular organization of receptors in the plasma membrane of cells is paramount for their functionality. We combined lattice light-sheet (LLS) microscopy with three-dimensional (3D) single-molecule localization microscopy (dSTORM) and single-particle tracking to quantify the expression and distribution, and mobility of CD56 receptors on whole fixed and living cells, finding that CD56 accumulated at cell–cell interfaces. For comparison, we investigated two other receptors, CD2 and CD45, which showed different expression levels and distributions in the plasma membrane. Overall, 3D-LLS-dSTORM enabled imaging and single-particle tracking of plasma membrane receptors with single-molecule sensitivity unperturbed by surface effects. Our results demonstrate that receptor distribution and mobility are largely unaffected by contact to the coverslip but the measured localization densities are in general lower at the basal plasma membrane due to partial limited accessibility for antibodies.

@article{waldchen2020wholecell, abstract = {The molecular organization of receptors in the plasma membrane of cells is paramount for their functionality. We combined lattice light-sheet (LLS) microscopy with three-dimensional (3D) single-molecule localization microscopy (dSTORM) and single-particle tracking to quantify the expression and distribution, and mobility of CD56 receptors on whole fixed and living cells, finding that CD56 accumulated at cell–cell interfaces. For comparison, we investigated two other receptors, CD2 and CD45, which showed different expression levels and distributions in the plasma membrane. Overall, 3D-LLS-dSTORM enabled imaging and single-particle tracking of plasma membrane receptors with single-molecule sensitivity unperturbed by surface effects. Our results demonstrate that receptor distribution and mobility are largely unaffected by contact to the coverslip but the measured localization densities are in general lower at the basal plasma membrane due to partial limited accessibility for antibodies.}, author = {Wäldchen, Felix and Schlegel, Jan and Götz, Ralph and Luciano, Michael and Schnermann, Martin and Doose, Sören and Sauer, Markus}, journal = {Nature Communications}, keywords = {sauer}, number = 1, pages = {887–}, title = {Whole-cell imaging of plasma membrane receptors by 3D lattice light-sheet dSTORM}, volume = 11, year = 2020 }

%0 Journal Article %1 waldchen2020wholecell %A Wäldchen, Felix %A Schlegel, Jan %A Götz, Ralph %A Luciano, Michael %A Schnermann, Martin %A Doose, Sören %A Sauer, Markus %D 2020 %J Nature Communications %N 1 %P 887-- %R 10.1038/s41467-020-14731-0 %T Whole-cell imaging of plasma membrane receptors by 3D lattice light-sheet dSTORM %U https://doi.org/10.1038/s41467-020-14731-0 %V 11 %X The molecular organization of receptors in the plasma membrane of cells is paramount for their functionality. We combined lattice light-sheet (LLS) microscopy with three-dimensional (3D) single-molecule localization microscopy (dSTORM) and single-particle tracking to quantify the expression and distribution, and mobility of CD56 receptors on whole fixed and living cells, finding that CD56 accumulated at cell–cell interfaces. For comparison, we investigated two other receptors, CD2 and CD45, which showed different expression levels and distributions in the plasma membrane. Overall, 3D-LLS-dSTORM enabled imaging and single-particle tracking of plasma membrane receptors with single-molecule sensitivity unperturbed by surface effects. Our results demonstrate that receptor distribution and mobility are largely unaffected by contact to the coverslip but the measured localization densities are in general lower at the basal plasma membrane due to partial limited accessibility for antibodies.
Molecular resolution imaging by post-labeling expansion single-molecule localization microscopy (Ex-SMLM) Zwettler, Fabian U.; Reinhard, Sebastian; Gambarotto, Davide; Bell, Toby D. M.; Hamel, Virginie; Guichard, Paul; Sauer, Markus in Nature Communications (2020). 11(1) 3388-.
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Expansion microscopy (ExM) enables super-resolution fluorescence imaging of physically expanded biological samples with conventional microscopes. By combining ExM with single-molecule localization microscopy (SMLM) it is potentially possible to approach the resolution of electron microscopy. However, current attempts to combine both methods remained challenging because of protein and fluorophore loss during digestion or denaturation, gelation, and the incompatibility of expanded polyelectrolyte hydrogels with photoswitching buffers. Here we show that re-embedding of expanded hydrogels enables dSTORM imaging of expanded samples and demonstrate that post-labeling ExM resolves the current limitations of super-resolution microscopy. Using microtubules as a reference structure and centrioles, we demonstrate that post-labeling Ex-SMLM preserves ultrastructural details, improves the labeling efficiency and reduces the positional error arising from linking fluorophores into the gel thus paving the way for super-resolution imaging of immunolabeled endogenous proteins with true molecular resolution.

@article{zwettler2020molecular, abstract = {Expansion microscopy (ExM) enables super-resolution fluorescence imaging of physically expanded biological samples with conventional microscopes. By combining ExM with single-molecule localization microscopy (SMLM) it is potentially possible to approach the resolution of electron microscopy. However, current attempts to combine both methods remained challenging because of protein and fluorophore loss during digestion or denaturation, gelation, and the incompatibility of expanded polyelectrolyte hydrogels with photoswitching buffers. Here we show that re-embedding of expanded hydrogels enables dSTORM imaging of expanded samples and demonstrate that post-labeling ExM resolves the current limitations of super-resolution microscopy. Using microtubules as a reference structure and centrioles, we demonstrate that post-labeling Ex-SMLM preserves ultrastructural details, improves the labeling efficiency and reduces the positional error arising from linking fluorophores into the gel thus paving the way for super-resolution imaging of immunolabeled endogenous proteins with true molecular resolution.}, author = {Zwettler, Fabian U. and Reinhard, Sebastian and Gambarotto, Davide and Bell, Toby D. M. and Hamel, Virginie and Guichard, Paul and Sauer, Markus}, journal = {Nature Communications}, keywords = {sauer}, number = 1, pages = {3388–}, title = {Molecular resolution imaging by post-labeling expansion single-molecule localization microscopy (Ex-SMLM)}, volume = 11, year = 2020 }

%0 Journal Article %1 zwettler2020molecular %A Zwettler, Fabian U. %A Reinhard, Sebastian %A Gambarotto, Davide %A Bell, Toby D. M. %A Hamel, Virginie %A Guichard, Paul %A Sauer, Markus %D 2020 %J Nature Communications %N 1 %P 3388-- %R 10.1038/s41467-020-17086-8 %T Molecular resolution imaging by post-labeling expansion single-molecule localization microscopy (Ex-SMLM) %U https://doi.org/10.1038/s41467-020-17086-8 %V 11 %X Expansion microscopy (ExM) enables super-resolution fluorescence imaging of physically expanded biological samples with conventional microscopes. By combining ExM with single-molecule localization microscopy (SMLM) it is potentially possible to approach the resolution of electron microscopy. However, current attempts to combine both methods remained challenging because of protein and fluorophore loss during digestion or denaturation, gelation, and the incompatibility of expanded polyelectrolyte hydrogels with photoswitching buffers. Here we show that re-embedding of expanded hydrogels enables dSTORM imaging of expanded samples and demonstrate that post-labeling ExM resolves the current limitations of super-resolution microscopy. Using microtubules as a reference structure and centrioles, we demonstrate that post-labeling Ex-SMLM preserves ultrastructural details, improves the labeling efficiency and reduces the positional error arising from linking fluorophores into the gel thus paving the way for super-resolution imaging of immunolabeled endogenous proteins with true molecular resolution.
Using Expansion Microscopy to Visualize and Characterize the Morphology of Mitochondrial Cristae Kunz, Tobias C.; Götz, Ralph; Gao, Shiqiang; Sauer, Markus; Kozjak-Pavlovic, Vera in Frontiers in Cell and Developmental Biology (2020). 8 617-.
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Mitochondria are double membrane bound organelles indispensable for biological processes such as apoptosis, cell signaling, and the production of many important metabolites, which includes ATP that is generated during the process known as oxidative phosphorylation (OXPHOS). The inner membrane contains folds called cristae, which increase the membrane surface and thus the amount of membrane-bound proteins necessary for the OXPHOS. These folds have been of great interest not only because of their importance for energy conversion, but also because changes in morphology have been linked to a broad range of diseases from cancer, diabetes, neurodegenerative diseases, to aging and infection. With a distance between opposing cristae membranes often below 100 nm, conventional fluorescence imaging cannot provide a resolution sufficient for resolving these structures. For this reason, various highly specialized super-resolution methods including dSTORM, PALM, STED, and SIM have been applied for cristae visualization. Expansion Microscopy (ExM) offers the possibility to perform super-resolution microscopy on conventional confocal microscopes by embedding the sample into a swellable hydrogel that is isotropically expanded by a factor of 4–4.5, improving the resolution to 60–70 nm on conventional confocal microscopes, which can be further increased to ∼ 30 nm laterally using SIM. Here, we demonstrate that the expression of the mitochondrial creatine kinase MtCK linked to marker protein GFP (MtCK-GFP), which localizes to the space between the outer and the inner mitochondrial membrane, can be used as a cristae marker. Applying ExM on mitochondria labeled with this construct enables visualization of morphological changes of cristae and localization studies of mitochondrial proteins relative to cristae without the need for specialized setups. For the first time we present the combination of specific mitochondrial intermembrane space labeling and ExM as a tool for studying internal structure of mitochondria.

@article{kunz2020using, abstract = {Mitochondria are double membrane bound organelles indispensable for biological processes such as apoptosis, cell signaling, and the production of many important metabolites, which includes ATP that is generated during the process known as oxidative phosphorylation (OXPHOS). The inner membrane contains folds called cristae, which increase the membrane surface and thus the amount of membrane-bound proteins necessary for the OXPHOS. These folds have been of great interest not only because of their importance for energy conversion, but also because changes in morphology have been linked to a broad range of diseases from cancer, diabetes, neurodegenerative diseases, to aging and infection. With a distance between opposing cristae membranes often below 100 nm, conventional fluorescence imaging cannot provide a resolution sufficient for resolving these structures. For this reason, various highly specialized super-resolution methods including dSTORM, PALM, STED, and SIM have been applied for cristae visualization. Expansion Microscopy (ExM) offers the possibility to perform super-resolution microscopy on conventional confocal microscopes by embedding the sample into a swellable hydrogel that is isotropically expanded by a factor of 4–4.5, improving the resolution to 60–70 nm on conventional confocal microscopes, which can be further increased to ∼ 30 nm laterally using SIM. Here, we demonstrate that the expression of the mitochondrial creatine kinase MtCK linked to marker protein GFP (MtCK-GFP), which localizes to the space between the outer and the inner mitochondrial membrane, can be used as a cristae marker. Applying ExM on mitochondria labeled with this construct enables visualization of morphological changes of cristae and localization studies of mitochondrial proteins relative to cristae without the need for specialized setups. For the first time we present the combination of specific mitochondrial intermembrane space labeling and ExM as a tool for studying internal structure of mitochondria.}, author = {Kunz, Tobias C. and Götz, Ralph and Gao, Shiqiang and Sauer, Markus and Kozjak-Pavlovic, Vera}, journal = {Frontiers in Cell and Developmental Biology}, keywords = {sauer}, pages = {617–}, title = {Using Expansion Microscopy to Visualize and Characterize the Morphology of Mitochondrial Cristae}, volume = 8, year = 2020 }

%0 Journal Article %1 kunz2020using %A Kunz, Tobias C. %A Götz, Ralph %A Gao, Shiqiang %A Sauer, Markus %A Kozjak-Pavlovic, Vera %D 2020 %J Frontiers in Cell and Developmental Biology %P 617-- %T Using Expansion Microscopy to Visualize and Characterize the Morphology of Mitochondrial Cristae %U https://www.frontiersin.org/article/10.3389/fcell.2020.00617 %V 8 %X Mitochondria are double membrane bound organelles indispensable for biological processes such as apoptosis, cell signaling, and the production of many important metabolites, which includes ATP that is generated during the process known as oxidative phosphorylation (OXPHOS). The inner membrane contains folds called cristae, which increase the membrane surface and thus the amount of membrane-bound proteins necessary for the OXPHOS. These folds have been of great interest not only because of their importance for energy conversion, but also because changes in morphology have been linked to a broad range of diseases from cancer, diabetes, neurodegenerative diseases, to aging and infection. With a distance between opposing cristae membranes often below 100 nm, conventional fluorescence imaging cannot provide a resolution sufficient for resolving these structures. For this reason, various highly specialized super-resolution methods including dSTORM, PALM, STED, and SIM have been applied for cristae visualization. Expansion Microscopy (ExM) offers the possibility to perform super-resolution microscopy on conventional confocal microscopes by embedding the sample into a swellable hydrogel that is isotropically expanded by a factor of 4–4.5, improving the resolution to 60–70 nm on conventional confocal microscopes, which can be further increased to ∼ 30 nm laterally using SIM. Here, we demonstrate that the expression of the mitochondrial creatine kinase MtCK linked to marker protein GFP (MtCK-GFP), which localizes to the space between the outer and the inner mitochondrial membrane, can be used as a cristae marker. Applying ExM on mitochondria labeled with this construct enables visualization of morphological changes of cristae and localization studies of mitochondrial proteins relative to cristae without the need for specialized setups. For the first time we present the combination of specific mitochondrial intermembrane space labeling and ExM as a tool for studying internal structure of mitochondria.
FocAn: automated 3D analysis of DNA repair foci in image stacks acquired by confocal fluorescence microscopy Memmel, Simon; Sisario, Dmitri; Zimmermann, Heiko; Sauer, Markus; Sukhorukov, Vladimir L.; Djuzenova, Cholpon S.; Flentje, Michael in BMC Bioinformatics (2020). 21(1) 27-.
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Phosphorylated histone H2AX, also known as γH2AX, forms μm-sized nuclear foci at the sites of DNA double-strand breaks (DSBs) induced by ionizing radiation and other agents. Due to their specificity and sensitivity, γH2AX immunoassays have become the gold standard for studying DSB induction and repair. One of these assays relies on the immunofluorescent staining of γH2AX followed by microscopic imaging and foci counting. During the last years, semi- and fully automated image analysis, capable of fast detection and quantification of γH2AX foci in large datasets of fluorescence images, are gradually replacing the traditional method of manual foci counting. A major drawback of the non-commercial software for foci counting (available so far) is that they are restricted to 2D-image data. In practice, these algorithms are useful for counting the foci located close to the midsection plane of the nucleus, while the out-of-plane foci are neglected.

@article{memmel2020focan, abstract = {Phosphorylated histone H2AX, also known as γH2AX, forms μm-sized nuclear foci at the sites of DNA double-strand breaks (DSBs) induced by ionizing radiation and other agents. Due to their specificity and sensitivity, γH2AX immunoassays have become the gold standard for studying DSB induction and repair. One of these assays relies on the immunofluorescent staining of γH2AX followed by microscopic imaging and foci counting. During the last years, semi- and fully automated image analysis, capable of fast detection and quantification of γH2AX foci in large datasets of fluorescence images, are gradually replacing the traditional method of manual foci counting. A major drawback of the non-commercial software for foci counting (available so far) is that they are restricted to 2D-image data. In practice, these algorithms are useful for counting the foci located close to the midsection plane of the nucleus, while the out-of-plane foci are neglected.}, author = {Memmel, Simon and Sisario, Dmitri and Zimmermann, Heiko and Sauer, Markus and Sukhorukov, Vladimir L. and Djuzenova, Cholpon S. and Flentje, Michael}, journal = {BMC Bioinformatics}, keywords = {vladimir}, number = 1, pages = {27–}, title = {FocAn: automated 3D analysis of DNA repair foci in image stacks acquired by confocal fluorescence microscopy}, volume = 21, year = 2020 }

%0 Journal Article %1 memmel2020focan %A Memmel, Simon %A Sisario, Dmitri %A Zimmermann, Heiko %A Sauer, Markus %A Sukhorukov, Vladimir L. %A Djuzenova, Cholpon S. %A Flentje, Michael %D 2020 %J BMC Bioinformatics %N 1 %P 27-- %R 10.1186/s12859-020-3370-8 %T FocAn: automated 3D analysis of DNA repair foci in image stacks acquired by confocal fluorescence microscopy %U https://doi.org/10.1186/s12859-020-3370-8 %V 21 %X Phosphorylated histone H2AX, also known as γH2AX, forms μm-sized nuclear foci at the sites of DNA double-strand breaks (DSBs) induced by ionizing radiation and other agents. Due to their specificity and sensitivity, γH2AX immunoassays have become the gold standard for studying DSB induction and repair. One of these assays relies on the immunofluorescent staining of γH2AX followed by microscopic imaging and foci counting. During the last years, semi- and fully automated image analysis, capable of fast detection and quantification of γH2AX foci in large datasets of fluorescence images, are gradually replacing the traditional method of manual foci counting. A major drawback of the non-commercial software for foci counting (available so far) is that they are restricted to 2D-image data. In practice, these algorithms are useful for counting the foci located close to the midsection plane of the nucleus, while the out-of-plane foci are neglected.
A Trojan Horse for live-cell super-resolution microscopy Beliu, Gerti; Sauer, Markus in Light: Science & Applications (2020). 9(1) 2-.
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New peptide vehicles enable the efficient live-cell labeling of intracellular organelles with cell-impermeable fluorescent probes by simple coincubation, paving the way for refined multicolor super-resolution fluorescence imaging.

@article{beliu2020trojan, abstract = {New peptide vehicles enable the efficient live-cell labeling of intracellular organelles with cell-impermeable fluorescent probes by simple coincubation, paving the way for refined multicolor super-resolution fluorescence imaging.}, author = {Beliu, Gerti and Sauer, Markus}, journal = {Light: Science & Applications}, keywords = {sauer}, number = 1, pages = {2–}, title = {A Trojan Horse for live-cell super-resolution microscopy}, volume = 9, year = 2020 }

%0 Journal Article %1 beliu2020trojan %A Beliu, Gerti %A Sauer, Markus %D 2020 %J Light: Science & Applications %N 1 %P 2-- %R 10.1038/s41377-019-0238-7 %T A Trojan Horse for live-cell super-resolution microscopy %U https://doi.org/10.1038/s41377-019-0238-7 %V 9 %X New peptide vehicles enable the efficient live-cell labeling of intracellular organelles with cell-impermeable fluorescent probes by simple coincubation, paving the way for refined multicolor super-resolution fluorescence imaging.
Expansion Microscopy for Cell Biology Analysis in Fungi Götz, Ralph; Panzer, Sabine; Trinks, Nora; Eilts, Janna; Wagener, Johannes; Turrà, David; Di Pietro, Antonio; Sauer, Markus; Terpitz, Ulrich in Frontiers in Microbiology (2020). 11
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Super-resolution microscopy has evolved as a powerful method for subdiffraction-resolution fluorescence imaging of cells and cellular organelles, but requires sophisticated and expensive installations. Expansion microscopy (ExM), which is based on the physical expansion of the cellular structure of interest, provides a cheap alternative to bypass the diffraction limit and enable super-resolution imaging on a conventional fluorescence microscope. While ExM has shown impressive results for the magnified visualization of proteins and RNAs in cells and tissues, it has not yet been applied in fungi, mainly due to their complex cell wall. Here we developed a method that enables reliable isotropic expansion of ascomycetes and basidiomycetes upon treatment with cell wall degrading enzymes. Confocal laser scanning microscopy (CLSM) and structured illumination microscopy (SIM) images of 4.5-fold expanded sporidia of Ustilago maydis expressing fluorescent fungal rhodopsins and hyphae of Fusarium oxysporum or Aspergillus fumigatus expressing either histone H1-mCherry together with Lifeact-sGFP or mRFP targeted to mitochondria, revealed details of subcellular structures with an estimated spatial resolution of around 30 nm. ExM is thus well suited for cell biology studies in fungi on conventional fluorescence microscopes.

@article{gotz2020expansion, abstract = {Super-resolution microscopy has evolved as a powerful method for subdiffraction-resolution fluorescence imaging of cells and cellular organelles, but requires sophisticated and expensive installations. Expansion microscopy (ExM), which is based on the physical expansion of the cellular structure of interest, provides a cheap alternative to bypass the diffraction limit and enable super-resolution imaging on a conventional fluorescence microscope. While ExM has shown impressive results for the magnified visualization of proteins and RNAs in cells and tissues, it has not yet been applied in fungi, mainly due to their complex cell wall. Here we developed a method that enables reliable isotropic expansion of ascomycetes and basidiomycetes upon treatment with cell wall degrading enzymes. Confocal laser scanning microscopy (CLSM) and structured illumination microscopy (SIM) images of 4.5-fold expanded sporidia of Ustilago maydis expressing fluorescent fungal rhodopsins and hyphae of Fusarium oxysporum or Aspergillus fumigatus expressing either histone H1-mCherry together with Lifeact-sGFP or mRFP targeted to mitochondria, revealed details of subcellular structures with an estimated spatial resolution of around 30 nm. ExM is thus well suited for cell biology studies in fungi on conventional fluorescence microscopes.}, author = {Götz, Ralph and Panzer, Sabine and Trinks, Nora and Eilts, Janna and Wagener, Johannes and Turrà, David and Di Pietro, Antonio and Sauer, Markus and Terpitz, Ulrich}, journal = {Frontiers in Microbiology}, keywords = {terpitz}, series = 574, title = {Expansion Microscopy for Cell Biology Analysis in Fungi}, volume = 11, year = 2020 }

%0 Journal Article %1 gotz2020expansion %A Götz, Ralph %A Panzer, Sabine %A Trinks, Nora %A Eilts, Janna %A Wagener, Johannes %A Turrà, David %A Di Pietro, Antonio %A Sauer, Markus %A Terpitz, Ulrich %B 574 %D 2020 %J Frontiers in Microbiology %T Expansion Microscopy for Cell Biology Analysis in Fungi %U https://www.frontiersin.org/article/10.3389/fmicb.2020.00574 %V 11 %X Super-resolution microscopy has evolved as a powerful method for subdiffraction-resolution fluorescence imaging of cells and cellular organelles, but requires sophisticated and expensive installations. Expansion microscopy (ExM), which is based on the physical expansion of the cellular structure of interest, provides a cheap alternative to bypass the diffraction limit and enable super-resolution imaging on a conventional fluorescence microscope. While ExM has shown impressive results for the magnified visualization of proteins and RNAs in cells and tissues, it has not yet been applied in fungi, mainly due to their complex cell wall. Here we developed a method that enables reliable isotropic expansion of ascomycetes and basidiomycetes upon treatment with cell wall degrading enzymes. Confocal laser scanning microscopy (CLSM) and structured illumination microscopy (SIM) images of 4.5-fold expanded sporidia of Ustilago maydis expressing fluorescent fungal rhodopsins and hyphae of Fusarium oxysporum or Aspergillus fumigatus expressing either histone H1-mCherry together with Lifeact-sGFP or mRFP targeted to mitochondria, revealed details of subcellular structures with an estimated spatial resolution of around 30 nm. ExM is thus well suited for cell biology studies in fungi on conventional fluorescence microscopes.
Super-resolution imaging reveals the nanoscale organization of metabotropic glutamate receptors at presynaptic active zones Siddig, Sana; Aufmkolk, Sarah; Doose, Sören; Jobin, Marie-Lise; Werner, Christian; Sauer, Markus; Calebiro, Davide in Sci Adv (2020). 6(16) eaay7193-.
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G protein–coupled receptors (GPCRs) play a fundamental role in the modulation of synaptic transmission. A pivotal example is provided by the metabotropic glutamate receptor type 4 (mGluR4), which inhibits glutamate release at presynaptic active zones (AZs). However, how GPCRs are organized within AZs to regulate neurotransmission remains largely unknown. Here, we applied two-color super-resolution imaging by direct stochastic optical reconstruction microscopy (dSTORM) to investigate the nanoscale organization of mGluR4 at parallel fiber AZs in the mouse cerebellum. We find an inhomogeneous distribution, with multiple nanodomains inside AZs, each containing, on average, one to two mGluR4 subunits. Within these nanodomains, mGluR4s are often localized in close proximity to voltage-dependent CaV2.1 channels and Munc-18-1, which are both essential for neurotransmitter release. These findings provide previously unknown insights into the molecular organization of GPCRs at AZs, suggesting a likely implication of a close association between mGluR4 and the secretory machinery in modulating synaptic transmission.

@article{siddig2020superresolution, abstract = {G protein–coupled receptors (GPCRs) play a fundamental role in the modulation of synaptic transmission. A pivotal example is provided by the metabotropic glutamate receptor type 4 (mGluR4), which inhibits glutamate release at presynaptic active zones (AZs). However, how GPCRs are organized within AZs to regulate neurotransmission remains largely unknown. Here, we applied two-color super-resolution imaging by direct stochastic optical reconstruction microscopy (dSTORM) to investigate the nanoscale organization of mGluR4 at parallel fiber AZs in the mouse cerebellum. We find an inhomogeneous distribution, with multiple nanodomains inside AZs, each containing, on average, one to two mGluR4 subunits. Within these nanodomains, mGluR4s are often localized in close proximity to voltage-dependent CaV2.1 channels and Munc-18-1, which are both essential for neurotransmitter release. These findings provide previously unknown insights into the molecular organization of GPCRs at AZs, suggesting a likely implication of a close association between mGluR4 and the secretory machinery in modulating synaptic transmission.}, author = {Siddig, Sana and Aufmkolk, Sarah and Doose, Sören and Jobin, Marie-Lise and Werner, Christian and Sauer, Markus and Calebiro, Davide}, journal = {Sci Adv}, keywords = {werner}, month = {apr}, number = 16, pages = {eaay7193–}, title = {Super-resolution imaging reveals the nanoscale organization of metabotropic glutamate receptors at presynaptic active zones}, volume = 6, year = 2020 }

%0 Journal Article %1 siddig2020superresolution %A Siddig, Sana %A Aufmkolk, Sarah %A Doose, Sören %A Jobin, Marie-Lise %A Werner, Christian %A Sauer, Markus %A Calebiro, Davide %D 2020 %J Sci Adv %N 16 %P eaay7193-- %R 10.1126/sciadv.aay7193 %T Super-resolution imaging reveals the nanoscale organization of metabotropic glutamate receptors at presynaptic active zones %U http://advances.sciencemag.org/content/6/16/eaay7193.abstract %V 6 %X G protein–coupled receptors (GPCRs) play a fundamental role in the modulation of synaptic transmission. A pivotal example is provided by the metabotropic glutamate receptor type 4 (mGluR4), which inhibits glutamate release at presynaptic active zones (AZs). However, how GPCRs are organized within AZs to regulate neurotransmission remains largely unknown. Here, we applied two-color super-resolution imaging by direct stochastic optical reconstruction microscopy (dSTORM) to investigate the nanoscale organization of mGluR4 at parallel fiber AZs in the mouse cerebellum. We find an inhomogeneous distribution, with multiple nanodomains inside AZs, each containing, on average, one to two mGluR4 subunits. Within these nanodomains, mGluR4s are often localized in close proximity to voltage-dependent CaV2.1 channels and Munc-18-1, which are both essential for neurotransmitter release. These findings provide previously unknown insights into the molecular organization of GPCRs at AZs, suggesting a likely implication of a close association between mGluR4 and the secretory machinery in modulating synaptic transmission.
Maintaining protein stability of ∆Np63 via USP28 is required by squamous cancer cells Prieto-Garcia, Cristian; Hartmann, Oliver; Reissland, Michaela; Braun, Fabian; Fischer, Thomas; Walz, Susanne; Schülein-Völk, Christina; Eilers, Ursula; Ade, Carsten P; Calzado, Marco A; Orian, Amir; Maric, Hans M; Münch, Christian; Rosenfeldt, Mathias; Eilers, Martin; Diefenbacher, Markus E in EMBO Molecular Medicine (2020). 12(4) e11101-.
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Abstract The transcription factor ?Np63 is a master regulator of epithelial cell identity and essential for the survival of squamous cell carcinoma (SCC) of lung, head and neck, oesophagus, cervix and skin. Here, we report that the deubiquitylase USP28 stabilizes ?Np63 and maintains elevated ?NP63 levels in SCC by counteracting its proteasome-mediated degradation. Impaired USP28 activity, either genetically or pharmacologically, abrogates the transcriptional identity and suppresses growth and survival of human SCC cells. CRISPR/Cas9-engineered in vivo mouse models establish that endogenous USP28 is strictly required for both induction and maintenance of lung SCC. Our data strongly suggest that targeting ?Np63 abundance via inhibition of USP28 is a promising strategy for the treatment of SCC tumours.

@article{prietogarcia2020maintaining, abstract = {Abstract The transcription factor ?Np63 is a master regulator of epithelial cell identity and essential for the survival of squamous cell carcinoma (SCC) of lung, head and neck, oesophagus, cervix and skin. Here, we report that the deubiquitylase USP28 stabilizes ?Np63 and maintains elevated ?NP63 levels in SCC by counteracting its proteasome-mediated degradation. Impaired USP28 activity, either genetically or pharmacologically, abrogates the transcriptional identity and suppresses growth and survival of human SCC cells. CRISPR/Cas9-engineered in vivo mouse models establish that endogenous USP28 is strictly required for both induction and maintenance of lung SCC. Our data strongly suggest that targeting ?Np63 abundance via inhibition of USP28 is a promising strategy for the treatment of SCC tumours.}, author = {Prieto-Garcia, Cristian and Hartmann, Oliver and Reissland, Michaela and Braun, Fabian and Fischer, Thomas and Walz, Susanne and Schülein-Völk, Christina and Eilers, Ursula and Ade, Carsten P and Calzado, Marco A and Orian, Amir and Maric, Hans M and Münch, Christian and Rosenfeldt, Mathias and Eilers, Martin and Diefenbacher, Markus E}, booktitle = {EMBO Molecular Medicine}, journal = {EMBO Molecular Medicine}, keywords = {maric}, month = {apr}, number = 4, pages = {e11101–}, publisher = {John Wiley & Sons, Ltd}, title = {Maintaining protein stability of ∆Np63 via USP28 is required by squamous cancer cells}, volume = 12, year = 2020 }

%0 Journal Article %1 prietogarcia2020maintaining %A Prieto-Garcia, Cristian %A Hartmann, Oliver %A Reissland, Michaela %A Braun, Fabian %A Fischer, Thomas %A Walz, Susanne %A Schülein-Völk, Christina %A Eilers, Ursula %A Ade, Carsten P %A Calzado, Marco A %A Orian, Amir %A Maric, Hans M %A Münch, Christian %A Rosenfeldt, Mathias %A Eilers, Martin %A Diefenbacher, Markus E %B EMBO Molecular Medicine %D 2020 %I John Wiley & Sons, Ltd %J EMBO Molecular Medicine %N 4 %P e11101-- %R 10.15252/emmm.201911101 %T Maintaining protein stability of ∆Np63 via USP28 is required by squamous cancer cells %U https://doi.org/10.15252/emmm.201911101 %V 12 %X Abstract The transcription factor ?Np63 is a master regulator of epithelial cell identity and essential for the survival of squamous cell carcinoma (SCC) of lung, head and neck, oesophagus, cervix and skin. Here, we report that the deubiquitylase USP28 stabilizes ?Np63 and maintains elevated ?NP63 levels in SCC by counteracting its proteasome-mediated degradation. Impaired USP28 activity, either genetically or pharmacologically, abrogates the transcriptional identity and suppresses growth and survival of human SCC cells. CRISPR/Cas9-engineered in vivo mouse models establish that endogenous USP28 is strictly required for both induction and maintenance of lung SCC. Our data strongly suggest that targeting ?Np63 abundance via inhibition of USP28 is a promising strategy for the treatment of SCC tumours.
A Novel Glycine Receptor Variant with Startle Disease Affects Syndapin I and Glycinergic Inhibition Langlhofer, Georg; Schaefer, Natascha; Maric, Hans M.; Keramidas, Angelo; Zhang, Yan; Baumann, Peter; Blum, Robert; Breitinger, Ulrike; Strømgaard, Kristian; Schlosser, Andreas; Kessels, Michael M.; Koch, Dennis; Qualmann, Britta; Breitinger, Hans-Georg; Lynch, Joseph W.; Villmann, Carmen in J. Neurosci. (2020). 40(25) 4954-.
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Glycine receptors (GlyRs) are the major mediators of fast synaptic inhibition in the adult human spinal cord and brainstem. Hereditary mutations to GlyRs can lead to the rare, but potentially fatal, neuromotor disorder hyperekplexia. Most mutations located in the large intracellular domain (TM3-4 loop) of the GlyRα1 impair surface expression levels of the receptors. The novel GLRA1 mutation P366L, located in the TM3-4 loop, showed normal surface expression but reduced chloride currents, and accelerated whole-cell desensitization observed in whole-cell recordings. At the single-channel level, we observed reduced unitary conductance accompanied by spontaneous opening events in the absence of extracellular glycine. Using peptide microarrays and tandem MS-based analysis methods, we show that the proline-rich stretch surrounding P366 mediates binding to syndapin I, an F-BAR domain protein involved in membrane remodeling. The disruption of the noncanonical Src homology 3 recognition motif by P366L reduces syndapin I binding. These data suggest that the GlyRα1 subunit interacts with intracellular binding partners and may therefore play a role in receptor trafficking or synaptic anchoring, a function thus far only ascribed to the GlyRβ subunit. Hence, the P366L GlyRα1 variant exhibits a unique set of properties that cumulatively affect GlyR functionality and thus might explain the neuropathological mechanism underlying hyperekplexia in the mutant carriers. P366L is the first dominant GLRA1 mutation identified within the GlyRα1 TM3-4 loop that affects GlyR physiology without altering protein expression at the whole-cell and surface levels.SIGNIFICANCE STATEMENT We show that the intracellular domain of the inhibitory glycine receptor α1 subunit contributes to trafficking and synaptic anchoring. A proline-rich stretch in this receptor domain forms a noncanonical recognition motif important for the interaction with syndapin I (PACSIN1). The disruption of this motif, as present in a human patient with hyperekplexia led to impaired syndapin I binding. Functional analysis revealed that the altered proline-rich stretch determines several functional physiological parameters of the ion channel (e.g., faster whole-cell desensitization) reduced unitary conductance and spontaneous opening events. Thus, the proline-rich stretch from the glycine receptor α1 subunit represents a multifunctional intracellular protein motif.

@article{langlhofer2020novel, abstract = {Glycine receptors (GlyRs) are the major mediators of fast synaptic inhibition in the adult human spinal cord and brainstem. Hereditary mutations to GlyRs can lead to the rare, but potentially fatal, neuromotor disorder hyperekplexia. Most mutations located in the large intracellular domain (TM3-4 loop) of the GlyRα1 impair surface expression levels of the receptors. The novel GLRA1 mutation P366L, located in the TM3-4 loop, showed normal surface expression but reduced chloride currents, and accelerated whole-cell desensitization observed in whole-cell recordings. At the single-channel level, we observed reduced unitary conductance accompanied by spontaneous opening events in the absence of extracellular glycine. Using peptide microarrays and tandem MS-based analysis methods, we show that the proline-rich stretch surrounding P366 mediates binding to syndapin I, an F-BAR domain protein involved in membrane remodeling. The disruption of the noncanonical Src homology 3 recognition motif by P366L reduces syndapin I binding. These data suggest that the GlyRα1 subunit interacts with intracellular binding partners and may therefore play a role in receptor trafficking or synaptic anchoring, a function thus far only ascribed to the GlyRβ subunit. Hence, the P366L GlyRα1 variant exhibits a unique set of properties that cumulatively affect GlyR functionality and thus might explain the neuropathological mechanism underlying hyperekplexia in the mutant carriers. P366L is the first dominant GLRA1 mutation identified within the GlyRα1 TM3-4 loop that affects GlyR physiology without altering protein expression at the whole-cell and surface levels.SIGNIFICANCE STATEMENT We show that the intracellular domain of the inhibitory glycine receptor α1 subunit contributes to trafficking and synaptic anchoring. A proline-rich stretch in this receptor domain forms a noncanonical recognition motif important for the interaction with syndapin I (PACSIN1). The disruption of this motif, as present in a human patient with hyperekplexia led to impaired syndapin I binding. Functional analysis revealed that the altered proline-rich stretch determines several functional physiological parameters of the ion channel (e.g., faster whole-cell desensitization) reduced unitary conductance and spontaneous opening events. Thus, the proline-rich stretch from the glycine receptor α1 subunit represents a multifunctional intracellular protein motif.}, author = {Langlhofer, Georg and Schaefer, Natascha and Maric, Hans M. and Keramidas, Angelo and Zhang, Yan and Baumann, Peter and Blum, Robert and Breitinger, Ulrike and Strømgaard, Kristian and Schlosser, Andreas and Kessels, Michael M. and Koch, Dennis and Qualmann, Britta and Breitinger, Hans-Georg and Lynch, Joseph W. and Villmann, Carmen}, journal = {J. Neurosci.}, keywords = {maric}, month = {jun}, number = 25, pages = {4954–}, title = {A Novel Glycine Receptor Variant with Startle Disease Affects Syndapin I and Glycinergic Inhibition}, volume = 40, year = 2020 }

%0 Journal Article %1 langlhofer2020novel %A Langlhofer, Georg %A Schaefer, Natascha %A Maric, Hans M. %A Keramidas, Angelo %A Zhang, Yan %A Baumann, Peter %A Blum, Robert %A Breitinger, Ulrike %A Strømgaard, Kristian %A Schlosser, Andreas %A Kessels, Michael M. %A Koch, Dennis %A Qualmann, Britta %A Breitinger, Hans-Georg %A Lynch, Joseph W. %A Villmann, Carmen %D 2020 %J J. Neurosci. %N 25 %P 4954-- %R 10.1523/JNEUROSCI.2490-19.2020 %T A Novel Glycine Receptor Variant with Startle Disease Affects Syndapin I and Glycinergic Inhibition %U http://www.jneurosci.org/content/40/25/4954.abstract %V 40 %X Glycine receptors (GlyRs) are the major mediators of fast synaptic inhibition in the adult human spinal cord and brainstem. Hereditary mutations to GlyRs can lead to the rare, but potentially fatal, neuromotor disorder hyperekplexia. Most mutations located in the large intracellular domain (TM3-4 loop) of the GlyRα1 impair surface expression levels of the receptors. The novel GLRA1 mutation P366L, located in the TM3-4 loop, showed normal surface expression but reduced chloride currents, and accelerated whole-cell desensitization observed in whole-cell recordings. At the single-channel level, we observed reduced unitary conductance accompanied by spontaneous opening events in the absence of extracellular glycine. Using peptide microarrays and tandem MS-based analysis methods, we show that the proline-rich stretch surrounding P366 mediates binding to syndapin I, an F-BAR domain protein involved in membrane remodeling. The disruption of the noncanonical Src homology 3 recognition motif by P366L reduces syndapin I binding. These data suggest that the GlyRα1 subunit interacts with intracellular binding partners and may therefore play a role in receptor trafficking or synaptic anchoring, a function thus far only ascribed to the GlyRβ subunit. Hence, the P366L GlyRα1 variant exhibits a unique set of properties that cumulatively affect GlyR functionality and thus might explain the neuropathological mechanism underlying hyperekplexia in the mutant carriers. P366L is the first dominant GLRA1 mutation identified within the GlyRα1 TM3-4 loop that affects GlyR physiology without altering protein expression at the whole-cell and surface levels.SIGNIFICANCE STATEMENT We show that the intracellular domain of the inhibitory glycine receptor α1 subunit contributes to trafficking and synaptic anchoring. A proline-rich stretch in this receptor domain forms a noncanonical recognition motif important for the interaction with syndapin I (PACSIN1). The disruption of this motif, as present in a human patient with hyperekplexia led to impaired syndapin I binding. Functional analysis revealed that the altered proline-rich stretch determines several functional physiological parameters of the ion channel (e.g., faster whole-cell desensitization) reduced unitary conductance and spontaneous opening events. Thus, the proline-rich stretch from the glycine receptor α1 subunit represents a multifunctional intracellular protein motif.
Confocal Fluorescence-Lifetime Single-Molecule Localization Microscopy Thiele, Jan Christoph; Helmerich, Dominic A.; Oleksiievets, Nazar; Tsukanov, Roman; Butkevich, Eugenia; Sauer, Markus; Nevskyi, Oleksii; Enderlein, Jörg in ACS Nano (2020). 14(10) 14190–14200.
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Fluorescence lifetime imaging microscopy is an important technique that adds another dimension to intensity and color acquired by conventional microscopy. In particular, it allows for multiplexing fluorescent labels that have otherwise similar spectral properties. Currently, the only super-resolution technique that is capable of recording super-resolved images with lifetime information is stimulated emission depletion microscopy. In contrast, all single-molecule localization microscopy (SMLM) techniques that employ wide-field cameras completely lack the lifetime dimension. Here, we combine fluorescence-lifetime confocal laser-scanning microscopy with SMLM for realizing single-molecule localization-based fluorescence-lifetime super-resolution imaging. Besides yielding images with a spatial resolution much beyond the diffraction limit, it determines the fluorescence lifetime of all localized molecules. We validate our technique by applying it to direct stochastic optical reconstruction microscopy and points accumulation for imaging in nanoscale topography imaging of fixed cells, and we demonstrate its multiplexing capability on samples with two different labels that differ only by fluorescence lifetime but not by their spectral properties.

@article{thiele2020confocal, abstract = {Fluorescence lifetime imaging microscopy is an important technique that adds another dimension to intensity and color acquired by conventional microscopy. In particular, it allows for multiplexing fluorescent labels that have otherwise similar spectral properties. Currently, the only super-resolution technique that is capable of recording super-resolved images with lifetime information is stimulated emission depletion microscopy. In contrast, all single-molecule localization microscopy (SMLM) techniques that employ wide-field cameras completely lack the lifetime dimension. Here, we combine fluorescence-lifetime confocal laser-scanning microscopy with SMLM for realizing single-molecule localization-based fluorescence-lifetime super-resolution imaging. Besides yielding images with a spatial resolution much beyond the diffraction limit, it determines the fluorescence lifetime of all localized molecules. We validate our technique by applying it to direct stochastic optical reconstruction microscopy and points accumulation for imaging in nanoscale topography imaging of fixed cells, and we demonstrate its multiplexing capability on samples with two different labels that differ only by fluorescence lifetime but not by their spectral properties.}, author = {Thiele, Jan Christoph and Helmerich, Dominic A. and Oleksiievets, Nazar and Tsukanov, Roman and Butkevich, Eugenia and Sauer, Markus and Nevskyi, Oleksii and Enderlein, Jörg}, booktitle = {ACS Nano}, journal = {ACS Nano}, keywords = {sauer}, month = {oct}, number = 10, pages = {14190–14200}, publisher = {American Chemical Society}, title = {Confocal Fluorescence-Lifetime Single-Molecule Localization Microscopy}, volume = 14, year = 2020 }

%0 Journal Article %1 thiele2020confocal %A Thiele, Jan Christoph %A Helmerich, Dominic A. %A Oleksiievets, Nazar %A Tsukanov, Roman %A Butkevich, Eugenia %A Sauer, Markus %A Nevskyi, Oleksii %A Enderlein, Jörg %B ACS Nano %D 2020 %I American Chemical Society %J ACS Nano %N 10 %P 14190--14200 %R 10.1021/acsnano.0c07322 %T Confocal Fluorescence-Lifetime Single-Molecule Localization Microscopy %U https://doi.org/10.1021/acsnano.0c07322 %V 14 %X Fluorescence lifetime imaging microscopy is an important technique that adds another dimension to intensity and color acquired by conventional microscopy. In particular, it allows for multiplexing fluorescent labels that have otherwise similar spectral properties. Currently, the only super-resolution technique that is capable of recording super-resolved images with lifetime information is stimulated emission depletion microscopy. In contrast, all single-molecule localization microscopy (SMLM) techniques that employ wide-field cameras completely lack the lifetime dimension. Here, we combine fluorescence-lifetime confocal laser-scanning microscopy with SMLM for realizing single-molecule localization-based fluorescence-lifetime super-resolution imaging. Besides yielding images with a spatial resolution much beyond the diffraction limit, it determines the fluorescence lifetime of all localized molecules. We validate our technique by applying it to direct stochastic optical reconstruction microscopy and points accumulation for imaging in nanoscale topography imaging of fixed cells, and we demonstrate its multiplexing capability on samples with two different labels that differ only by fluorescence lifetime but not by their spectral properties.

2019[ to top ]

Registration and Visualization of Correlative Super-Resolution Microscopy Data Reinhard, Sebastian; Aufmkolk, Sarah; Sauer, Markus; Doose, Sören in Biophysical Journal (2019). 116(11) 2073–2078.
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We introduce a method for registration and visualization of correlative super-resolution microscopy images from different microscopy techniques. We established an automated registration procedure based on the generalized Hough transform. We developed a software tool to apply this algorithm and visualize correlated images from structured illumination microscopy (SIM) and direct stochastic optical reconstruction microscopy (dSTORM). To demonstrate the potential of this super-resolution correlator, we visualize the distribution of the presynaptic protein bassoon in the active zones of synapses in the molecular layer of the mouse cerebellum. First, a multiple labeled sample is imaged by SIM, followed by imaging of one of the fluorescent labels by dSTORM. To avoid the use of artificial fiducial markers, we used the signal of Alexa Fluor 647 recorded in switching buffer on the two microscopes for image superposition. We recorded multicolor SIM images in 20-μm thick brain slices to identify synapses in the dendritic system of Purkinje cells and put higher-resolved dSTORM images of the synaptic distribution of bassoon in registry.

@article{reinhard2019registration, abstract = {We introduce a method for registration and visualization of correlative super-resolution microscopy images from different microscopy techniques. We established an automated registration procedure based on the generalized Hough transform. We developed a software tool to apply this algorithm and visualize correlated images from structured illumination microscopy (SIM) and direct stochastic optical reconstruction microscopy (dSTORM). To demonstrate the potential of this super-resolution correlator, we visualize the distribution of the presynaptic protein bassoon in the active zones of synapses in the molecular layer of the mouse cerebellum. First, a multiple labeled sample is imaged by SIM, followed by imaging of one of the fluorescent labels by dSTORM. To avoid the use of artificial fiducial markers, we used the signal of Alexa Fluor 647 recorded in switching buffer on the two microscopes for image superposition. We recorded multicolor SIM images in 20-μm thick brain slices to identify synapses in the dendritic system of Purkinje cells and put higher-resolved dSTORM images of the synaptic distribution of bassoon in registry.}, author = {Reinhard, Sebastian and Aufmkolk, Sarah and Sauer, Markus and Doose, Sören}, journal = {Biophysical Journal}, keywords = {sauer}, number = 11, pages = {2073–2078}, title = {Registration and Visualization of Correlative Super-Resolution Microscopy Data}, volume = 116, year = 2019 }

%0 Journal Article %1 reinhard2019registration %A Reinhard, Sebastian %A Aufmkolk, Sarah %A Sauer, Markus %A Doose, Sören %D 2019 %J Biophysical Journal %N 11 %P 2073--2078 %R https://doi.org/10.1016/j.bpj.2019.04.029 %T Registration and Visualization of Correlative Super-Resolution Microscopy Data %U http://www.sciencedirect.com/science/article/pii/S000634951930373X %V 116 %X We introduce a method for registration and visualization of correlative super-resolution microscopy images from different microscopy techniques. We established an automated registration procedure based on the generalized Hough transform. We developed a software tool to apply this algorithm and visualize correlated images from structured illumination microscopy (SIM) and direct stochastic optical reconstruction microscopy (dSTORM). To demonstrate the potential of this super-resolution correlator, we visualize the distribution of the presynaptic protein bassoon in the active zones of synapses in the molecular layer of the mouse cerebellum. First, a multiple labeled sample is imaged by SIM, followed by imaging of one of the fluorescent labels by dSTORM. To avoid the use of artificial fiducial markers, we used the signal of Alexa Fluor 647 recorded in switching buffer on the two microscopes for image superposition. We recorded multicolor SIM images in 20-μm thick brain slices to identify synapses in the dendritic system of Purkinje cells and put higher-resolved dSTORM images of the synaptic distribution of bassoon in registry.
FSP1 is a glutathione-independent ferroptosis suppressor Doll, Sebastian; Freitas, Florencio Porto; Shah, Ron; Aldrovandi, Maceler; da Silva, Milene Costa; Ingold, Irina; Grocin, Andrea Goya; Xavier da Silva, Thamara Nishida; Panzilius, Elena; Scheel, Christina H.; Mourão, André; Buday, Katalin; Sato, Mami; Wanninger, Jonas; Vignane, Thibaut; Mohana, Vaishnavi; Rehberg, Markus; Flatley, Andrew; Schepers, Aloys; Kurz, Andreas; White, Daniel; Sauer, Markus; Sattler, Michael; Tate, Edward William; Schmitz, Werner; Schulze, Almut; O’Donnell, Valerie; Proneth, Bettina; Popowicz, Grzegorz M.; Pratt, Derek A.; Angeli, José Pedro Friedmann; Conrad, Marcus in Nature (2019). 575(7784) 693–698.
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Ferroptosis is an iron-dependent form of necrotic cell death marked by oxidative damage to phospholipids1,2. To date, ferroptosis has been thought to be controlled only by the phospholipid hydroperoxide-reducing enzyme glutathione peroxidase 4 (GPX4)3,4 and radical-trapping antioxidants5,6. However, elucidation of the factors that underlie the sensitivity of a given cell type to ferroptosis7 is crucial to understand the pathophysiological role of ferroptosis and how it may be exploited for the treatment of cancer. Although metabolic constraints8 and phospholipid composition9,10 contribute to ferroptosis sensitivity, no cell-autonomous mechanisms have been identified that account for the resistance of cells to ferroptosis. Here we used an expression cloning approach to identify genes in human cancer cells that are able to complement the loss of GPX4. We found that the flavoprotein apoptosis-inducing factor mitochondria-associated 2 (AIFM2) is a previously unrecognized anti-ferroptotic gene. AIFM2, which we renamed ferroptosis suppressor protein 1 (FSP1) and which was initially described as a pro-apoptotic gene11, confers protection against ferroptosis elicited by GPX4 deletion. We further demonstrate that the suppression of ferroptosis by FSP1 is mediated by ubiquinone (also known as coenzyme Q10, CoQ10): the reduced form, ubiquinol, traps lipid peroxyl radicals that mediate lipid peroxidation, whereas FSP1 catalyses the regeneration of CoQ10 using NAD(P)H. Pharmacological targeting of FSP1 strongly synergizes with GPX4 inhibitors to trigger ferroptosis in a number of cancer entities. In conclusion, the FSP1–CoQ10–NAD(P)H pathway exists as a stand-alone parallel system, which co-operates with GPX4 and glutathione to suppress phospholipid peroxidation and ferroptosis.

@article{doll2019glutathioneindependent, abstract = {Ferroptosis is an iron-dependent form of necrotic cell death marked by oxidative damage to phospholipids1,2. To date, ferroptosis has been thought to be controlled only by the phospholipid hydroperoxide-reducing enzyme glutathione peroxidase 4 (GPX4)3,4 and radical-trapping antioxidants5,6. However, elucidation of the factors that underlie the sensitivity of a given cell type to ferroptosis7 is crucial to understand the pathophysiological role of ferroptosis and how it may be exploited for the treatment of cancer. Although metabolic constraints8 and phospholipid composition9,10 contribute to ferroptosis sensitivity, no cell-autonomous mechanisms have been identified that account for the resistance of cells to ferroptosis. Here we used an expression cloning approach to identify genes in human cancer cells that are able to complement the loss of GPX4. We found that the flavoprotein apoptosis-inducing factor mitochondria-associated 2 (AIFM2) is a previously unrecognized anti-ferroptotic gene. AIFM2, which we renamed ferroptosis suppressor protein 1 (FSP1) and which was initially described as a pro-apoptotic gene11, confers protection against ferroptosis elicited by GPX4 deletion. We further demonstrate that the suppression of ferroptosis by FSP1 is mediated by ubiquinone (also known as coenzyme Q10, CoQ10): the reduced form, ubiquinol, traps lipid peroxyl radicals that mediate lipid peroxidation, whereas FSP1 catalyses the regeneration of CoQ10 using NAD(P)H. Pharmacological targeting of FSP1 strongly synergizes with GPX4 inhibitors to trigger ferroptosis in a number of cancer entities. In conclusion, the FSP1–CoQ10–NAD(P)H pathway exists as a stand-alone parallel system, which co-operates with GPX4 and glutathione to suppress phospholipid peroxidation and ferroptosis.}, author = {Doll, Sebastian and Freitas, Florencio Porto and Shah, Ron and Aldrovandi, Maceler and da Silva, Milene Costa and Ingold, Irina and Grocin, Andrea Goya and Xavier da Silva, Thamara Nishida and Panzilius, Elena and Scheel, Christina H. and Mourão, André and Buday, Katalin and Sato, Mami and Wanninger, Jonas and Vignane, Thibaut and Mohana, Vaishnavi and Rehberg, Markus and Flatley, Andrew and Schepers, Aloys and Kurz, Andreas and White, Daniel and Sauer, Markus and Sattler, Michael and Tate, Edward William and Schmitz, Werner and Schulze, Almut and O’Donnell, Valerie and Proneth, Bettina and Popowicz, Grzegorz M. and Pratt, Derek A. and Angeli, José Pedro Friedmann and Conrad, Marcus}, journal = {Nature}, keywords = {sauer}, number = 7784, pages = {693–698}, title = {FSP1 is a glutathione-independent ferroptosis suppressor}, volume = 575, year = 2019 }

%0 Journal Article %1 doll2019glutathioneindependent %A Doll, Sebastian %A Freitas, Florencio Porto %A Shah, Ron %A Aldrovandi, Maceler %A da Silva, Milene Costa %A Ingold, Irina %A Grocin, Andrea Goya %A Xavier da Silva, Thamara Nishida %A Panzilius, Elena %A Scheel, Christina H. %A Mourão, André %A Buday, Katalin %A Sato, Mami %A Wanninger, Jonas %A Vignane, Thibaut %A Mohana, Vaishnavi %A Rehberg, Markus %A Flatley, Andrew %A Schepers, Aloys %A Kurz, Andreas %A White, Daniel %A Sauer, Markus %A Sattler, Michael %A Tate, Edward William %A Schmitz, Werner %A Schulze, Almut %A O’Donnell, Valerie %A Proneth, Bettina %A Popowicz, Grzegorz M. %A Pratt, Derek A. %A Angeli, José Pedro Friedmann %A Conrad, Marcus %D 2019 %J Nature %N 7784 %P 693--698 %R 10.1038/s41586-019-1707-0 %T FSP1 is a glutathione-independent ferroptosis suppressor %U https://doi.org/10.1038/s41586-019-1707-0 %V 575 %X Ferroptosis is an iron-dependent form of necrotic cell death marked by oxidative damage to phospholipids1,2. To date, ferroptosis has been thought to be controlled only by the phospholipid hydroperoxide-reducing enzyme glutathione peroxidase 4 (GPX4)3,4 and radical-trapping antioxidants5,6. However, elucidation of the factors that underlie the sensitivity of a given cell type to ferroptosis7 is crucial to understand the pathophysiological role of ferroptosis and how it may be exploited for the treatment of cancer. Although metabolic constraints8 and phospholipid composition9,10 contribute to ferroptosis sensitivity, no cell-autonomous mechanisms have been identified that account for the resistance of cells to ferroptosis. Here we used an expression cloning approach to identify genes in human cancer cells that are able to complement the loss of GPX4. We found that the flavoprotein apoptosis-inducing factor mitochondria-associated 2 (AIFM2) is a previously unrecognized anti-ferroptotic gene. AIFM2, which we renamed ferroptosis suppressor protein 1 (FSP1) and which was initially described as a pro-apoptotic gene11, confers protection against ferroptosis elicited by GPX4 deletion. We further demonstrate that the suppression of ferroptosis by FSP1 is mediated by ubiquinone (also known as coenzyme Q10, CoQ10): the reduced form, ubiquinol, traps lipid peroxyl radicals that mediate lipid peroxidation, whereas FSP1 catalyses the regeneration of CoQ10 using NAD(P)H. Pharmacological targeting of FSP1 strongly synergizes with GPX4 inhibitors to trigger ferroptosis in a number of cancer entities. In conclusion, the FSP1–CoQ10–NAD(P)H pathway exists as a stand-alone parallel system, which co-operates with GPX4 and glutathione to suppress phospholipid peroxidation and ferroptosis.
Super-resolution microscopy reveals ultra-low CD19 expression on myeloma cells that triggers elimination by CD19 CAR-T Nerreter, Thomas; Letschert, Sebastian; Götz, Ralph; Doose, Sören; Danhof, Sophia; Einsele, Hermann; Sauer, Markus; Hudecek, Michael in Nature Communications (2019). 10(1) 3137-.
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Immunotherapy with chimeric antigen receptor-engineered T-cells (CAR-T) is under investigation in multiple myeloma. There are reports of myeloma remission after CD19 CAR-T therapy, although CD19 is hardly detectable on myeloma cells by flow cytometry (FC). We apply single molecule-sensitive direct stochastic optical reconstruction microscopy (dSTORM), and demonstrate CD19 expression on a fraction of myeloma cells (10.3–80%) in 10 out of 14 patients (density: 13–5,000 molecules per cell). In contrast, FC detects CD19 in only 2 of these 10 patients, on a smaller fraction of cells. Treatment with CD19 CAR-T in vitro results in elimination of CD19-positive myeloma cells, including those with <100 CD19 molecules per cell. Similar data are obtained by dSTORM analyses of CD20 expression on myeloma cells and CD20 CAR-T. These data establish a sensitivity threshold for CAR-T and illustrate how super-resolution microscopy can guide patient selection in immunotherapy to exploit ultra-low density antigens.

@article{nerreter2019superresolution, abstract = {Immunotherapy with chimeric antigen receptor-engineered T-cells (CAR-T) is under investigation in multiple myeloma. There are reports of myeloma remission after CD19 CAR-T therapy, although CD19 is hardly detectable on myeloma cells by flow cytometry (FC). We apply single molecule-sensitive direct stochastic optical reconstruction microscopy (dSTORM), and demonstrate CD19 expression on a fraction of myeloma cells (10.3–80%) in 10 out of 14 patients (density: 13–5,000 molecules per cell). In contrast, FC detects CD19 in only 2 of these 10 patients, on a smaller fraction of cells. Treatment with CD19 CAR-T in vitro results in elimination of CD19-positive myeloma cells, including those with <100 CD19 molecules per cell. Similar data are obtained by dSTORM analyses of CD20 expression on myeloma cells and CD20 CAR-T. These data establish a sensitivity threshold for CAR-T and illustrate how super-resolution microscopy can guide patient selection in immunotherapy to exploit ultra-low density antigens.}, author = {Nerreter, Thomas and Letschert, Sebastian and Götz, Ralph and Doose, Sören and Danhof, Sophia and Einsele, Hermann and Sauer, Markus and Hudecek, Michael}, journal = {Nature Communications}, keywords = {sauer}, number = 1, pages = {3137–}, title = {Super-resolution microscopy reveals ultra-low CD19 expression on myeloma cells that triggers elimination by CD19 CAR-T}, volume = 10, year = 2019 }

%0 Journal Article %1 nerreter2019superresolution %A Nerreter, Thomas %A Letschert, Sebastian %A Götz, Ralph %A Doose, Sören %A Danhof, Sophia %A Einsele, Hermann %A Sauer, Markus %A Hudecek, Michael %D 2019 %J Nature Communications %N 1 %P 3137-- %R 10.1038/s41467-019-10948-w %T Super-resolution microscopy reveals ultra-low CD19 expression on myeloma cells that triggers elimination by CD19 CAR-T %U https://doi.org/10.1038/s41467-019-10948-w %V 10 %X Immunotherapy with chimeric antigen receptor-engineered T-cells (CAR-T) is under investigation in multiple myeloma. There are reports of myeloma remission after CD19 CAR-T therapy, although CD19 is hardly detectable on myeloma cells by flow cytometry (FC). We apply single molecule-sensitive direct stochastic optical reconstruction microscopy (dSTORM), and demonstrate CD19 expression on a fraction of myeloma cells (10.3–80%) in 10 out of 14 patients (density: 13–5,000 molecules per cell). In contrast, FC detects CD19 in only 2 of these 10 patients, on a smaller fraction of cells. Treatment with CD19 CAR-T in vitro results in elimination of CD19-positive myeloma cells, including those with <100 CD19 molecules per cell. Similar data are obtained by dSTORM analyses of CD20 expression on myeloma cells and CD20 CAR-T. These data establish a sensitivity threshold for CAR-T and illustrate how super-resolution microscopy can guide patient selection in immunotherapy to exploit ultra-low density antigens.
Imaging cellular ultrastructures using expansion microscopy (U-ExM) Gambarotto, Davide; Zwettler, Fabian U.; Le Guennec, Maeva; Schmidt-Cernohorska, Marketa; Fortun, Denis; Borgers, Susanne; Heine, Jörn; Schloetel, Jan-Gero; Reuss, Matthias; Unser, Michael; Boyden, Edward S.; Sauer, Markus; Hamel, Virginie; Guichard, Paul in Nature Methods (2019). 16(1) 71–74.
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Determining the structure and composition of macromolecular assemblies is a major challenge in biology. Here we describe ultrastructure expansion microscopy (U-ExM), an extension of expansion microscopy that allows the visualization of preserved ultrastructures by optical microscopy. This method allows for near-native expansion of diverse structures in vitro and in cells; when combined with super-resolution microscopy, it unveiled details of ultrastructural organization, such as centriolar chirality, that could otherwise be observed only by electron microscopy.

@article{gambarotto2019imaging, abstract = {Determining the structure and composition of macromolecular assemblies is a major challenge in biology. Here we describe ultrastructure expansion microscopy (U-ExM), an extension of expansion microscopy that allows the visualization of preserved ultrastructures by optical microscopy. This method allows for near-native expansion of diverse structures in vitro and in cells; when combined with super-resolution microscopy, it unveiled details of ultrastructural organization, such as centriolar chirality, that could otherwise be observed only by electron microscopy.}, author = {Gambarotto, Davide and Zwettler, Fabian U. and Le Guennec, Maeva and Schmidt-Cernohorska, Marketa and Fortun, Denis and Borgers, Susanne and Heine, Jörn and Schloetel, Jan-Gero and Reuss, Matthias and Unser, Michael and Boyden, Edward S. and Sauer, Markus and Hamel, Virginie and Guichard, Paul}, journal = {Nature Methods}, keywords = {sauer}, number = 1, pages = {71–74}, title = {Imaging cellular ultrastructures using expansion microscopy (U-ExM)}, volume = 16, year = 2019 }

%0 Journal Article %1 gambarotto2019imaging %A Gambarotto, Davide %A Zwettler, Fabian U. %A Le Guennec, Maeva %A Schmidt-Cernohorska, Marketa %A Fortun, Denis %A Borgers, Susanne %A Heine, Jörn %A Schloetel, Jan-Gero %A Reuss, Matthias %A Unser, Michael %A Boyden, Edward S. %A Sauer, Markus %A Hamel, Virginie %A Guichard, Paul %D 2019 %J Nature Methods %N 1 %P 71--74 %R 10.1038/s41592-018-0238-1 %T Imaging cellular ultrastructures using expansion microscopy (U-ExM) %U https://doi.org/10.1038/s41592-018-0238-1 %V 16 %X Determining the structure and composition of macromolecular assemblies is a major challenge in biology. Here we describe ultrastructure expansion microscopy (U-ExM), an extension of expansion microscopy that allows the visualization of preserved ultrastructures by optical microscopy. This method allows for near-native expansion of diverse structures in vitro and in cells; when combined with super-resolution microscopy, it unveiled details of ultrastructural organization, such as centriolar chirality, that could otherwise be observed only by electron microscopy.
Differential effects of the Akt inhibitor MK-2206 on migration and radiation sensitivity of glioblastoma cells Djuzenova, Cholpon S.; Fiedler, Vanessa; Memmel, Simon; Katzer, Astrid; Sisario, Dmitri; Brosch, Philippa K.; Göhrung, Alexander; Frister, Svenja; Zimmermann, Heiko; Flentje, Michael; Sukhorukov, Vladimir L. in BMC Cancer (2019). 19(1) 299-.
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Most tumor cells show aberrantly activated Akt which leads to increased cell survival and resistance to cancer radiotherapy. Therefore, targeting Akt can be a promising strategy for radiosensitization. Here, we explore the impact of the Akt inhibitor MK-2206 alone and in combination with the dual PI3K and mTOR inhibitor PI-103 on the radiation sensitivity of glioblastoma cells. In addition, we examine migration of drug-treated cells.

@article{djuzenova2019differential, abstract = {Most tumor cells show aberrantly activated Akt which leads to increased cell survival and resistance to cancer radiotherapy. Therefore, targeting Akt can be a promising strategy for radiosensitization. Here, we explore the impact of the Akt inhibitor MK-2206 alone and in combination with the dual PI3K and mTOR inhibitor PI-103 on the radiation sensitivity of glioblastoma cells. In addition, we examine migration of drug-treated cells.}, author = {Djuzenova, Cholpon S. and Fiedler, Vanessa and Memmel, Simon and Katzer, Astrid and Sisario, Dmitri and Brosch, Philippa K. and Göhrung, Alexander and Frister, Svenja and Zimmermann, Heiko and Flentje, Michael and Sukhorukov, Vladimir L.}, journal = {BMC Cancer}, keywords = {vladimir}, number = 1, pages = {299–}, title = {Differential effects of the Akt inhibitor MK-2206 on migration and radiation sensitivity of glioblastoma cells}, volume = 19, year = 2019 }

%0 Journal Article %1 djuzenova2019differential %A Djuzenova, Cholpon S. %A Fiedler, Vanessa %A Memmel, Simon %A Katzer, Astrid %A Sisario, Dmitri %A Brosch, Philippa K. %A Göhrung, Alexander %A Frister, Svenja %A Zimmermann, Heiko %A Flentje, Michael %A Sukhorukov, Vladimir L. %D 2019 %J BMC Cancer %N 1 %P 299-- %R 10.1186/s12885-019-5517-4 %T Differential effects of the Akt inhibitor MK-2206 on migration and radiation sensitivity of glioblastoma cells %U https://doi.org/10.1186/s12885-019-5517-4 %V 19 %X Most tumor cells show aberrantly activated Akt which leads to increased cell survival and resistance to cancer radiotherapy. Therefore, targeting Akt can be a promising strategy for radiosensitization. Here, we explore the impact of the Akt inhibitor MK-2206 alone and in combination with the dual PI3K and mTOR inhibitor PI-103 on the radiation sensitivity of glioblastoma cells. In addition, we examine migration of drug-treated cells.
Methionine in a protein hydrophobic core drives tight interactions required for assembly of spider silk Heiby, Julia C.; Goretzki, Benedikt; Johnson, Christopher M.; Hellmich, Ute A.; Neuweiler, Hannes in Nature Communications (2019). 10(1) 4378-.
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Web spiders connect silk proteins, so-called spidroins, into fibers of extraordinary toughness. The spidroin N-terminal domain (NTD) plays a pivotal role in this process: it polymerizes spidroins through a complex mechanism of dimerization. Here we analyze sequences of spidroin NTDs and find an unusually high content of the amino acid methionine. We simultaneously mutate all methionines present in the hydrophobic core of a spidroin NTD from a nursery web spider’s dragline silk to leucine. The mutated NTD is strongly stabilized and folds at the theoretical speed limit. The structure of the mutant is preserved, yet its ability to dimerize is substantially impaired. We find that side chains of core methionines serve to mobilize the fold, which can thereby access various conformations and adapt the association interface for tight binding. Methionine in a hydrophobic core equips a protein with the capacity to dynamically change shape and thus to optimize its function.

@article{heiby2019methionine, abstract = {Web spiders connect silk proteins, so-called spidroins, into fibers of extraordinary toughness. The spidroin N-terminal domain (NTD) plays a pivotal role in this process: it polymerizes spidroins through a complex mechanism of dimerization. Here we analyze sequences of spidroin NTDs and find an unusually high content of the amino acid methionine. We simultaneously mutate all methionines present in the hydrophobic core of a spidroin NTD from a nursery web spider’s dragline silk to leucine. The mutated NTD is strongly stabilized and folds at the theoretical speed limit. The structure of the mutant is preserved, yet its ability to dimerize is substantially impaired. We find that side chains of core methionines serve to mobilize the fold, which can thereby access various conformations and adapt the association interface for tight binding. Methionine in a hydrophobic core equips a protein with the capacity to dynamically change shape and thus to optimize its function.}, author = {Heiby, Julia C. and Goretzki, Benedikt and Johnson, Christopher M. and Hellmich, Ute A. and Neuweiler, Hannes}, journal = {Nature Communications}, keywords = {hannes}, number = 1, pages = {4378–}, title = {Methionine in a protein hydrophobic core drives tight interactions required for assembly of spider silk}, volume = 10, year = 2019 }

%0 Journal Article %1 heiby2019methionine %A Heiby, Julia C. %A Goretzki, Benedikt %A Johnson, Christopher M. %A Hellmich, Ute A. %A Neuweiler, Hannes %D 2019 %J Nature Communications %N 1 %P 4378-- %R 10.1038/s41467-019-12365-5 %T Methionine in a protein hydrophobic core drives tight interactions required for assembly of spider silk %U https://doi.org/10.1038/s41467-019-12365-5 %V 10 %X Web spiders connect silk proteins, so-called spidroins, into fibers of extraordinary toughness. The spidroin N-terminal domain (NTD) plays a pivotal role in this process: it polymerizes spidroins through a complex mechanism of dimerization. Here we analyze sequences of spidroin NTDs and find an unusually high content of the amino acid methionine. We simultaneously mutate all methionines present in the hydrophobic core of a spidroin NTD from a nursery web spider’s dragline silk to leucine. The mutated NTD is strongly stabilized and folds at the theoretical speed limit. The structure of the mutant is preserved, yet its ability to dimerize is substantially impaired. We find that side chains of core methionines serve to mobilize the fold, which can thereby access various conformations and adapt the association interface for tight binding. Methionine in a hydrophobic core equips a protein with the capacity to dynamically change shape and thus to optimize its function.
On-target restoration of a split T cell-engaging antibody for precision immunotherapy Banaszek, Agnes; Bumm, Thomas G. P.; Nowotny, Boris; Geis, Maria; Jacob, Kim; Wölfl, Matthias; Trebing, Johannes; Kucka, Kirstin; Kouhestani, Dina; Gogishvili, Tea; Krenz, Bastian; Lutz, Justina; Rasche, Leo; Hönemann, Dirk; Neuweiler, Hannes; Heiby, Julia C.; Bargou, Ralf C.; Wajant, Harald; Einsele, Hermann; Riethmüller, Gert; Stuhler, Gernot in Nature Communications (2019). 10(1) 5387-.
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T cell-engaging immunotherapies are changing the landscape of current cancer care. However, suitable target antigens are scarce, restricting these strategies to very few tumor types. Here, we report on a T cell-engaging antibody derivative that comes in two complementary halves and addresses antigen combinations instead of single molecules. Each half, now coined hemibody, contains an antigen-specific single-chain variable fragment (scFv) fused to either the variable light (VL) or variable heavy (VH) chain domain of an anti-CD3 antibody. When the two hemibodies simultaneously bind their respective antigens on a single cell, they align and reconstitute the original CD3-binding site to engage T cells. Employing preclinical models for aggressive leukemia and breast cancer, we show that by the combinatorial nature of this approach, T lymphocytes exclusively eliminate dual antigen-positive cells while sparing single positive bystanders. This allows for precision targeting of cancers not amenable to current immunotherapies.

@article{banaszek2019ontarget, abstract = {T cell-engaging immunotherapies are changing the landscape of current cancer care. However, suitable target antigens are scarce, restricting these strategies to very few tumor types. Here, we report on a T cell-engaging antibody derivative that comes in two complementary halves and addresses antigen combinations instead of single molecules. Each half, now coined hemibody, contains an antigen-specific single-chain variable fragment (scFv) fused to either the variable light (VL) or variable heavy (VH) chain domain of an anti-CD3 antibody. When the two hemibodies simultaneously bind their respective antigens on a single cell, they align and reconstitute the original CD3-binding site to engage T cells. Employing preclinical models for aggressive leukemia and breast cancer, we show that by the combinatorial nature of this approach, T lymphocytes exclusively eliminate dual antigen-positive cells while sparing single positive bystanders. This allows for precision targeting of cancers not amenable to current immunotherapies.}, author = {Banaszek, Agnes and Bumm, Thomas G. P. and Nowotny, Boris and Geis, Maria and Jacob, Kim and Wölfl, Matthias and Trebing, Johannes and Kucka, Kirstin and Kouhestani, Dina and Gogishvili, Tea and Krenz, Bastian and Lutz, Justina and Rasche, Leo and Hönemann, Dirk and Neuweiler, Hannes and Heiby, Julia C. and Bargou, Ralf C. and Wajant, Harald and Einsele, Hermann and Riethmüller, Gert and Stuhler, Gernot}, journal = {Nature Communications}, keywords = {hannes}, number = 1, pages = {5387–}, title = {On-target restoration of a split T cell-engaging antibody for precision immunotherapy}, volume = 10, year = 2019 }

%0 Journal Article %1 banaszek2019ontarget %A Banaszek, Agnes %A Bumm, Thomas G. P. %A Nowotny, Boris %A Geis, Maria %A Jacob, Kim %A Wölfl, Matthias %A Trebing, Johannes %A Kucka, Kirstin %A Kouhestani, Dina %A Gogishvili, Tea %A Krenz, Bastian %A Lutz, Justina %A Rasche, Leo %A Hönemann, Dirk %A Neuweiler, Hannes %A Heiby, Julia C. %A Bargou, Ralf C. %A Wajant, Harald %A Einsele, Hermann %A Riethmüller, Gert %A Stuhler, Gernot %D 2019 %J Nature Communications %N 1 %P 5387-- %R 10.1038/s41467-019-13196-0 %T On-target restoration of a split T cell-engaging antibody for precision immunotherapy %U https://doi.org/10.1038/s41467-019-13196-0 %V 10 %X T cell-engaging immunotherapies are changing the landscape of current cancer care. However, suitable target antigens are scarce, restricting these strategies to very few tumor types. Here, we report on a T cell-engaging antibody derivative that comes in two complementary halves and addresses antigen combinations instead of single molecules. Each half, now coined hemibody, contains an antigen-specific single-chain variable fragment (scFv) fused to either the variable light (VL) or variable heavy (VH) chain domain of an anti-CD3 antibody. When the two hemibodies simultaneously bind their respective antigens on a single cell, they align and reconstitute the original CD3-binding site to engage T cells. Employing preclinical models for aggressive leukemia and breast cancer, we show that by the combinatorial nature of this approach, T lymphocytes exclusively eliminate dual antigen-positive cells while sparing single positive bystanders. This allows for precision targeting of cancers not amenable to current immunotherapies.
Super-Resolution Microscopy Reveals Local Accumulation of Plasma Membrane Gangliosides at Neisseria meningitidis Invasion Sites Schlegel, Jan; Peters, Simon; Doose, Sören; Schubert-Unkmeir, Alexandra; Sauer, Markus in Frontiers in Cell and Developmental Biology (2019). 7 194-.
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Neisseria meningitidis (meningococcus) is a Gram-negative bacterium responsible for epidemic meningitis and sepsis worldwide. A critical step in the development of meningitis is the interaction of bacteria with cells forming the blood-cerebrospinal fluid barrier, which requires tight adhesion of the pathogen to highly specialized brain endothelial cells. Two endothelial receptors, CD147 and the β2-adrenergic receptor, have been found to be sequentially recruited by meningococci involving the interaction with type IV pilus. Despite the identification of cellular key players in bacterial adhesion the detailed mechanism of invasion is still poorly understood. Here, we investigated cellular dynamics and mobility of the type IV pilus receptor CD147 upon treatment with pili enriched fractions and specific antibodies directed against two extracellular Ig-like domains in living human brain microvascular endothelial cells. Modulation of CD147 mobility after ligand binding revealed by single-molecule tracking experiments demonstrates receptor activation and indicates plasma membrane rearrangements. Exploiting the binding of Shiga (STxB) and Cholera toxin B (CTxB) subunits to the two native plasma membrane sphingolipids globotriaosylceramide (Gb3) and raft-associated monosialotetrahexosylganglioside GM1, respectively, we investigated their involvement in bacterial invasion by super-resolution microscopy. Structured illumination microscopy (SIM) and direct stochastic optical reconstruction microscopy (dSTORM) unraveled accumulation and coating of meningococci with GM1 upon cellular uptake. Blocking of CTxB binding sites did not impair bacterial adhesion but dramatically reduced bacterial invasion efficiency. In addition, cell cycle arrest in G1 phase induced by serum starvation led to an overall increase of GM1 molecules in the plasma membrane and consequently also in bacterial invasion efficiency. Our results will help to understand downstream signaling events after initial type IV pilus-host cell interactions and thus have general impact on the development of new therapeutics targeting key molecules involved in infection.

@article{schlegel2019superresolution, abstract = {Neisseria meningitidis (meningococcus) is a Gram-negative bacterium responsible for epidemic meningitis and sepsis worldwide. A critical step in the development of meningitis is the interaction of bacteria with cells forming the blood-cerebrospinal fluid barrier, which requires tight adhesion of the pathogen to highly specialized brain endothelial cells. Two endothelial receptors, CD147 and the β2-adrenergic receptor, have been found to be sequentially recruited by meningococci involving the interaction with type IV pilus. Despite the identification of cellular key players in bacterial adhesion the detailed mechanism of invasion is still poorly understood. Here, we investigated cellular dynamics and mobility of the type IV pilus receptor CD147 upon treatment with pili enriched fractions and specific antibodies directed against two extracellular Ig-like domains in living human brain microvascular endothelial cells. Modulation of CD147 mobility after ligand binding revealed by single-molecule tracking experiments demonstrates receptor activation and indicates plasma membrane rearrangements. Exploiting the binding of Shiga (STxB) and Cholera toxin B (CTxB) subunits to the two native plasma membrane sphingolipids globotriaosylceramide (Gb3) and raft-associated monosialotetrahexosylganglioside GM1, respectively, we investigated their involvement in bacterial invasion by super-resolution microscopy. Structured illumination microscopy (SIM) and direct stochastic optical reconstruction microscopy (dSTORM) unraveled accumulation and coating of meningococci with GM1 upon cellular uptake. Blocking of CTxB binding sites did not impair bacterial adhesion but dramatically reduced bacterial invasion efficiency. In addition, cell cycle arrest in G1 phase induced by serum starvation led to an overall increase of GM1 molecules in the plasma membrane and consequently also in bacterial invasion efficiency. Our results will help to understand downstream signaling events after initial type IV pilus-host cell interactions and thus have general impact on the development of new therapeutics targeting key molecules involved in infection.}, author = {Schlegel, Jan and Peters, Simon and Doose, Sören and Schubert-Unkmeir, Alexandra and Sauer, Markus}, journal = {Frontiers in Cell and Developmental Biology}, keywords = {sauer}, pages = {194–}, title = {Super-Resolution Microscopy Reveals Local Accumulation of Plasma Membrane Gangliosides at Neisseria meningitidis Invasion Sites}, volume = 7, year = 2019 }

%0 Journal Article %1 schlegel2019superresolution %A Schlegel, Jan %A Peters, Simon %A Doose, Sören %A Schubert-Unkmeir, Alexandra %A Sauer, Markus %D 2019 %J Frontiers in Cell and Developmental Biology %P 194-- %T Super-Resolution Microscopy Reveals Local Accumulation of Plasma Membrane Gangliosides at Neisseria meningitidis Invasion Sites %U https://www.frontiersin.org/article/10.3389/fcell.2019.00194 %V 7 %X Neisseria meningitidis (meningococcus) is a Gram-negative bacterium responsible for epidemic meningitis and sepsis worldwide. A critical step in the development of meningitis is the interaction of bacteria with cells forming the blood-cerebrospinal fluid barrier, which requires tight adhesion of the pathogen to highly specialized brain endothelial cells. Two endothelial receptors, CD147 and the β2-adrenergic receptor, have been found to be sequentially recruited by meningococci involving the interaction with type IV pilus. Despite the identification of cellular key players in bacterial adhesion the detailed mechanism of invasion is still poorly understood. Here, we investigated cellular dynamics and mobility of the type IV pilus receptor CD147 upon treatment with pili enriched fractions and specific antibodies directed against two extracellular Ig-like domains in living human brain microvascular endothelial cells. Modulation of CD147 mobility after ligand binding revealed by single-molecule tracking experiments demonstrates receptor activation and indicates plasma membrane rearrangements. Exploiting the binding of Shiga (STxB) and Cholera toxin B (CTxB) subunits to the two native plasma membrane sphingolipids globotriaosylceramide (Gb3) and raft-associated monosialotetrahexosylganglioside GM1, respectively, we investigated their involvement in bacterial invasion by super-resolution microscopy. Structured illumination microscopy (SIM) and direct stochastic optical reconstruction microscopy (dSTORM) unraveled accumulation and coating of meningococci with GM1 upon cellular uptake. Blocking of CTxB binding sites did not impair bacterial adhesion but dramatically reduced bacterial invasion efficiency. In addition, cell cycle arrest in G1 phase induced by serum starvation led to an overall increase of GM1 molecules in the plasma membrane and consequently also in bacterial invasion efficiency. Our results will help to understand downstream signaling events after initial type IV pilus-host cell interactions and thus have general impact on the development of new therapeutics targeting key molecules involved in infection.
Platelet lamellipodium formation is not required for thrombus formation and stability Schurr, Yvonne; Sperr, Andreas; Volz, Julia; Beck, Sarah; Reil, Lucy; Kusch, Charly; Eiring, Patrick; Bryson, Sheila; Sauer, Markus; Nieswandt, Bernhard; Machesky, Laura; Bender, Markus in Blood (2019). 134 2318–2329.
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During platelet spreading, the actin cytoskeleton undergoes rapid rearrangement, forming filopodia and lamellipodia. Controversial data have been published on the role of lamellipodia in thrombus formation and stability. The Wiskott-Aldrich syndrome protein-family verprolin-homologous protein (WAVE)-regulatory complex, which has been shown in other cells to drive lamellipodium formation by enhancing actin nucleation via the actin-related protein 2/3 (Arp2/3) complex, is activated by Ras-related C3 botulinum toxin substrate 1 (Rac1) interaction with the WAVE complex subunit cytoplasmic fragile X mental retardation 1–interacting protein 1 (Cyfip1). We analyzed Cyfip1flox/floxPf4-Cre mice to investigate the role of Cyfip1 in platelet function. These mice displayed normal platelet counts and a slight reduction in platelet volume. Activation of mutant platelets was only moderately reduced to all tested agonists as measured by αIIbβ3 integrin activation and P-selectin surface exposure. However, lamellipodium formation of mutant platelets was completely abolished on different matrices. Nevertheless, Cyfip1-deficient platelets formed stable thrombi on collagen fibers ex vivo and in 2 models of occlusive arterial thrombosis in vivo. Similarly, the hemostatic function and maintenance of vascular integrity during inflammation of the skin and lung were unaltered in the mutant mice. Investigation of platelet morphology in an induced thrombus under flow revealed that platelets rather form filopodia in the thrombus shell, and are flattened with filopodium-like structures when in direct contact to collagen fibers at the bottom of the thrombus. We provide for the first time direct evidence that platelet lamellipodium formation is not required for stable thrombus formation, and that morphological changes of platelets differ between a static spreading assay and thrombus formation under flow.

@article{schurr2019platelet, abstract = {During platelet spreading, the actin cytoskeleton undergoes rapid rearrangement, forming filopodia and lamellipodia. Controversial data have been published on the role of lamellipodia in thrombus formation and stability. The Wiskott-Aldrich syndrome protein-family verprolin-homologous protein (WAVE)-regulatory complex, which has been shown in other cells to drive lamellipodium formation by enhancing actin nucleation via the actin-related protein 2/3 (Arp2/3) complex, is activated by Ras-related C3 botulinum toxin substrate 1 (Rac1) interaction with the WAVE complex subunit cytoplasmic fragile X mental retardation 1–interacting protein 1 (Cyfip1). We analyzed Cyfip1flox/floxPf4-Cre mice to investigate the role of Cyfip1 in platelet function. These mice displayed normal platelet counts and a slight reduction in platelet volume. Activation of mutant platelets was only moderately reduced to all tested agonists as measured by αIIbβ3 integrin activation and P-selectin surface exposure. However, lamellipodium formation of mutant platelets was completely abolished on different matrices. Nevertheless, Cyfip1-deficient platelets formed stable thrombi on collagen fibers ex vivo and in 2 models of occlusive arterial thrombosis in vivo. Similarly, the hemostatic function and maintenance of vascular integrity during inflammation of the skin and lung were unaltered in the mutant mice. Investigation of platelet morphology in an induced thrombus under flow revealed that platelets rather form filopodia in the thrombus shell, and are flattened with filopodium-like structures when in direct contact to collagen fibers at the bottom of the thrombus. We provide for the first time direct evidence that platelet lamellipodium formation is not required for stable thrombus formation, and that morphological changes of platelets differ between a static spreading assay and thrombus formation under flow.}, author = {Schurr, Yvonne and Sperr, Andreas and Volz, Julia and Beck, Sarah and Reil, Lucy and Kusch, Charly and Eiring, Patrick and Bryson, Sheila and Sauer, Markus and Nieswandt, Bernhard and Machesky, Laura and Bender, Markus}, booktitle = {Blood}, journal = {Blood}, keywords = {sauer}, pages = {2318-2329}, series = 25, title = {Platelet lamellipodium formation is not required for thrombus formation and stability}, volume = 134, year = 2019 }

%0 Journal Article %1 schurr2019platelet %A Schurr, Yvonne %A Sperr, Andreas %A Volz, Julia %A Beck, Sarah %A Reil, Lucy %A Kusch, Charly %A Eiring, Patrick %A Bryson, Sheila %A Sauer, Markus %A Nieswandt, Bernhard %A Machesky, Laura %A Bender, Markus %B Blood %D 2019 %J Blood %P 2318-2329 %T Platelet lamellipodium formation is not required for thrombus formation and stability %U https://doi.org/10.1182/blood.2019002105 %V 134 %X During platelet spreading, the actin cytoskeleton undergoes rapid rearrangement, forming filopodia and lamellipodia. Controversial data have been published on the role of lamellipodia in thrombus formation and stability. The Wiskott-Aldrich syndrome protein-family verprolin-homologous protein (WAVE)-regulatory complex, which has been shown in other cells to drive lamellipodium formation by enhancing actin nucleation via the actin-related protein 2/3 (Arp2/3) complex, is activated by Ras-related C3 botulinum toxin substrate 1 (Rac1) interaction with the WAVE complex subunit cytoplasmic fragile X mental retardation 1–interacting protein 1 (Cyfip1). We analyzed Cyfip1flox/floxPf4-Cre mice to investigate the role of Cyfip1 in platelet function. These mice displayed normal platelet counts and a slight reduction in platelet volume. Activation of mutant platelets was only moderately reduced to all tested agonists as measured by αIIbβ3 integrin activation and P-selectin surface exposure. However, lamellipodium formation of mutant platelets was completely abolished on different matrices. Nevertheless, Cyfip1-deficient platelets formed stable thrombi on collagen fibers ex vivo and in 2 models of occlusive arterial thrombosis in vivo. Similarly, the hemostatic function and maintenance of vascular integrity during inflammation of the skin and lung were unaltered in the mutant mice. Investigation of platelet morphology in an induced thrombus under flow revealed that platelets rather form filopodia in the thrombus shell, and are flattened with filopodium-like structures when in direct contact to collagen fibers at the bottom of the thrombus. We provide for the first time direct evidence that platelet lamellipodium formation is not required for stable thrombus formation, and that morphological changes of platelets differ between a static spreading assay and thrombus formation under flow.
Detection of Chlamydia Developmental Forms and Secreted Effectors by Expansion Microscopy Kunz, Tobias C.; Götz, Ralph; Sauer, Markus; Rudel, Thomas in Frontiers in Cellular and Infection Microbiology (2019). 9 276-.
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Expansion microscopy (ExM) is a novel tool to improve the resolution of fluorescence-based microscopy that has not yet been used to visualize intracellular pathogens. Here we show the expansion of the intracellular pathogen Chlamydia trachomatis, enabling to differentiate its two distinct forms, catabolic active reticulate bodies (RB) and infectious elementary bodies (EB), on a conventional confocal microscope. We show that ExM enables the possibility to precisely locate chlamydial effector proteins, such as CPAF or Cdu1, within and outside of the chlamydial inclusion. Thus, we claim that ExM offers the possibility to address a broad range of questions and may be useful for further research on various intracellular pathogens.

@article{kunz2019detection, abstract = {Expansion microscopy (ExM) is a novel tool to improve the resolution of fluorescence-based microscopy that has not yet been used to visualize intracellular pathogens. Here we show the expansion of the intracellular pathogen Chlamydia trachomatis, enabling to differentiate its two distinct forms, catabolic active reticulate bodies (RB) and infectious elementary bodies (EB), on a conventional confocal microscope. We show that ExM enables the possibility to precisely locate chlamydial effector proteins, such as CPAF or Cdu1, within and outside of the chlamydial inclusion. Thus, we claim that ExM offers the possibility to address a broad range of questions and may be useful for further research on various intracellular pathogens.}, author = {Kunz, Tobias C. and Götz, Ralph and Sauer, Markus and Rudel, Thomas}, journal = {Frontiers in Cellular and Infection Microbiology}, keywords = {sauer}, pages = {276–}, title = {Detection of Chlamydia Developmental Forms and Secreted Effectors by Expansion Microscopy}, volume = 9, year = 2019 }

%0 Journal Article %1 kunz2019detection %A Kunz, Tobias C. %A Götz, Ralph %A Sauer, Markus %A Rudel, Thomas %D 2019 %J Frontiers in Cellular and Infection Microbiology %P 276-- %T Detection of Chlamydia Developmental Forms and Secreted Effectors by Expansion Microscopy %U https://www.frontiersin.org/article/10.3389/fcimb.2019.00276 %V 9 %X Expansion microscopy (ExM) is a novel tool to improve the resolution of fluorescence-based microscopy that has not yet been used to visualize intracellular pathogens. Here we show the expansion of the intracellular pathogen Chlamydia trachomatis, enabling to differentiate its two distinct forms, catabolic active reticulate bodies (RB) and infectious elementary bodies (EB), on a conventional confocal microscope. We show that ExM enables the possibility to precisely locate chlamydial effector proteins, such as CPAF or Cdu1, within and outside of the chlamydial inclusion. Thus, we claim that ExM offers the possibility to address a broad range of questions and may be useful for further research on various intracellular pathogens.
Measles Virus Infection Fosters Dendritic Cell Motility in a 3D Environment to Enhance Transmission to Target Cells in the Respiratory Epithelium Derakhshani, Shaghayegh; Kurz, Andreas; Japtok, Lukasz; Schumacher, Fabian; Pilgram, Lisa; Steinke, Maria; Kleuser, Burkhard; Sauer, Markus; Schneider-Schaulies, Sibylle; Avota, Elita in Frontiers in Immunology (2019). 10 1294-.
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Transmission of measles virus (MV) from dendritic to airway epithelial cells is considered as crucial to viral spread late in infection. Therefore, pathways and effectors governing this process are promising targets for intervention. To identify these, we established a 3D respiratory tract model where MV transmission by infected dendritic cells (DCs) relied on the presence of nectin-4 on H358 lung epithelial cells. Access to recipient cells is an important prerequisite for transmission, and we therefore analyzed migration of MV-exposed DC cultures within the model. Surprisingly, enhanced motility towards the epithelial layer was observed for MV-infected DCs as compared to their uninfected siblings. This occurred independently of factors released from H358 cells indicating that MV infection triggered cytoskeletal remodeling associated with DC polarization enforced velocity cell autonomously. Accordingly, the latter was also observed for MV-infected DCs in collagen matrices and was particularly sensitive to ROCK inhibition indicating infected DCs preferentially employed the amoeboid migration mode. This was also implicated by loss of podosomes and reduced filopodial activity both of which were retained in MV-exposed uninfected DCs. Evidently, sphingosine kinase (SphK) and sphingosine-1-phosphate (S1P) as produced in response to virus-infection in DCs contributed to enhanced velocity because this was abrogated upon inhibition of sphingosine kinase activity. These findings indicate that MV infection promotes a push-and-squeeze fast amoeboid migration mode via the SphK/S1P system characterized by loss of filopodia and podosome dissolution. Consequently, this enables rapid trafficking of virus towards epithelial cells during viral exit.

@article{derakhshani2019measles, abstract = {Transmission of measles virus (MV) from dendritic to airway epithelial cells is considered as crucial to viral spread late in infection. Therefore, pathways and effectors governing this process are promising targets for intervention. To identify these, we established a 3D respiratory tract model where MV transmission by infected dendritic cells (DCs) relied on the presence of nectin-4 on H358 lung epithelial cells. Access to recipient cells is an important prerequisite for transmission, and we therefore analyzed migration of MV-exposed DC cultures within the model. Surprisingly, enhanced motility towards the epithelial layer was observed for MV-infected DCs as compared to their uninfected siblings. This occurred independently of factors released from H358 cells indicating that MV infection triggered cytoskeletal remodeling associated with DC polarization enforced velocity cell autonomously. Accordingly, the latter was also observed for MV-infected DCs in collagen matrices and was particularly sensitive to ROCK inhibition indicating infected DCs preferentially employed the amoeboid migration mode. This was also implicated by loss of podosomes and reduced filopodial activity both of which were retained in MV-exposed uninfected DCs. Evidently, sphingosine kinase (SphK) and sphingosine-1-phosphate (S1P) as produced in response to virus-infection in DCs contributed to enhanced velocity because this was abrogated upon inhibition of sphingosine kinase activity. These findings indicate that MV infection promotes a push-and-squeeze fast amoeboid migration mode via the SphK/S1P system characterized by loss of filopodia and podosome dissolution. Consequently, this enables rapid trafficking of virus towards epithelial cells during viral exit.}, author = {Derakhshani, Shaghayegh and Kurz, Andreas and Japtok, Lukasz and Schumacher, Fabian and Pilgram, Lisa and Steinke, Maria and Kleuser, Burkhard and Sauer, Markus and Schneider-Schaulies, Sibylle and Avota, Elita}, journal = {Frontiers in Immunology}, keywords = {sauer}, pages = {1294–}, title = {Measles Virus Infection Fosters Dendritic Cell Motility in a 3D Environment to Enhance Transmission to Target Cells in the Respiratory Epithelium}, volume = 10, year = 2019 }

%0 Journal Article %1 derakhshani2019measles %A Derakhshani, Shaghayegh %A Kurz, Andreas %A Japtok, Lukasz %A Schumacher, Fabian %A Pilgram, Lisa %A Steinke, Maria %A Kleuser, Burkhard %A Sauer, Markus %A Schneider-Schaulies, Sibylle %A Avota, Elita %D 2019 %J Frontiers in Immunology %P 1294-- %T Measles Virus Infection Fosters Dendritic Cell Motility in a 3D Environment to Enhance Transmission to Target Cells in the Respiratory Epithelium %U https://www.frontiersin.org/article/10.3389/fimmu.2019.01294 %V 10 %X Transmission of measles virus (MV) from dendritic to airway epithelial cells is considered as crucial to viral spread late in infection. Therefore, pathways and effectors governing this process are promising targets for intervention. To identify these, we established a 3D respiratory tract model where MV transmission by infected dendritic cells (DCs) relied on the presence of nectin-4 on H358 lung epithelial cells. Access to recipient cells is an important prerequisite for transmission, and we therefore analyzed migration of MV-exposed DC cultures within the model. Surprisingly, enhanced motility towards the epithelial layer was observed for MV-infected DCs as compared to their uninfected siblings. This occurred independently of factors released from H358 cells indicating that MV infection triggered cytoskeletal remodeling associated with DC polarization enforced velocity cell autonomously. Accordingly, the latter was also observed for MV-infected DCs in collagen matrices and was particularly sensitive to ROCK inhibition indicating infected DCs preferentially employed the amoeboid migration mode. This was also implicated by loss of podosomes and reduced filopodial activity both of which were retained in MV-exposed uninfected DCs. Evidently, sphingosine kinase (SphK) and sphingosine-1-phosphate (S1P) as produced in response to virus-infection in DCs contributed to enhanced velocity because this was abrogated upon inhibition of sphingosine kinase activity. These findings indicate that MV infection promotes a push-and-squeeze fast amoeboid migration mode via the SphK/S1P system characterized by loss of filopodia and podosome dissolution. Consequently, this enables rapid trafficking of virus towards epithelial cells during viral exit.
Super-resolution microscopy demystified Schermelleh, Lothar; Ferrand, Alexia; Huser, Thomas; Eggeling, Christian; Sauer, Markus; Biehlmaier, Oliver; Drummen, Gregor P. C. in Nature Cell Biology (2019). 21(1) 72–84.
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Super-resolution microscopy (SRM) bypasses the diffraction limit, a physical barrier that restricts the optical resolution to roughly 250 nm and was previously thought to be impenetrable. SRM techniques allow the visualization of subcellular organization with unprecedented detail, but also confront biologists with the challenge of selecting the best-suited approach for their particular research question. Here, we provide guidance on how to use SRM techniques advantageously for investigating cellular structures and dynamics to promote new discoveries.

@article{schermelleh2019superresolution, abstract = {Super-resolution microscopy (SRM) bypasses the diffraction limit, a physical barrier that restricts the optical resolution to roughly 250 nm and was previously thought to be impenetrable. SRM techniques allow the visualization of subcellular organization with unprecedented detail, but also confront biologists with the challenge of selecting the best-suited approach for their particular research question. Here, we provide guidance on how to use SRM techniques advantageously for investigating cellular structures and dynamics to promote new discoveries.}, author = {Schermelleh, Lothar and Ferrand, Alexia and Huser, Thomas and Eggeling, Christian and Sauer, Markus and Biehlmaier, Oliver and Drummen, Gregor P. C.}, journal = {Nature Cell Biology}, keywords = {sauer}, number = 1, pages = {72–84}, title = {Super-resolution microscopy demystified}, volume = 21, year = 2019 }

%0 Journal Article %1 schermelleh2019superresolution %A Schermelleh, Lothar %A Ferrand, Alexia %A Huser, Thomas %A Eggeling, Christian %A Sauer, Markus %A Biehlmaier, Oliver %A Drummen, Gregor P. C. %D 2019 %J Nature Cell Biology %N 1 %P 72--84 %R 10.1038/s41556-018-0251-8 %T Super-resolution microscopy demystified %U https://doi.org/10.1038/s41556-018-0251-8 %V 21 %X Super-resolution microscopy (SRM) bypasses the diffraction limit, a physical barrier that restricts the optical resolution to roughly 250 nm and was previously thought to be impenetrable. SRM techniques allow the visualization of subcellular organization with unprecedented detail, but also confront biologists with the challenge of selecting the best-suited approach for their particular research question. Here, we provide guidance on how to use SRM techniques advantageously for investigating cellular structures and dynamics to promote new discoveries.
The conserved NxNNWHW motif in Aha-type co-chaperones modulates the kinetics of Hsp90 ATPase stimulation Mercier, Rebecca; Wolmarans, Annemarie; Schubert, Jonathan; Neuweiler, Hannes; Johnson, Jill L.; LaPointe, Paul in Nature Communications (2019). 10(1) 1273-.
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Hsp90 is a dimeric molecular chaperone that is essential for the folding and activation of hundreds of client proteins. Co-chaperone proteins regulate the ATP-driven Hsp90 client activation cycle. Aha-type co-chaperones are the most potent stimulators of the Hsp90 ATPase activity but the relationship between ATPase regulation and in vivo activity is poorly understood. We report here that the most strongly conserved region of Aha-type co-chaperones, the N terminal NxNNWHW motif, modulates the apparent affinity of Hsp90 for nucleotide substrates. The ability of yeast Aha-type co-chaperones to act in vivo is ablated when the N terminal NxNNWHW motif is removed. This work suggests that nucleotide exchange during the Hsp90 functional cycle may be more important than rate of catalysis.

@article{mercier2019conserved, abstract = {Hsp90 is a dimeric molecular chaperone that is essential for the folding and activation of hundreds of client proteins. Co-chaperone proteins regulate the ATP-driven Hsp90 client activation cycle. Aha-type co-chaperones are the most potent stimulators of the Hsp90 ATPase activity but the relationship between ATPase regulation and in vivo activity is poorly understood. We report here that the most strongly conserved region of Aha-type co-chaperones, the N terminal NxNNWHW motif, modulates the apparent affinity of Hsp90 for nucleotide substrates. The ability of yeast Aha-type co-chaperones to act in vivo is ablated when the N terminal NxNNWHW motif is removed. This work suggests that nucleotide exchange during the Hsp90 functional cycle may be more important than rate of catalysis.}, author = {Mercier, Rebecca and Wolmarans, Annemarie and Schubert, Jonathan and Neuweiler, Hannes and Johnson, Jill L. and LaPointe, Paul}, journal = {Nature Communications}, keywords = {hannes}, number = 1, pages = {1273–}, title = {The conserved NxNNWHW motif in Aha-type co-chaperones modulates the kinetics of Hsp90 ATPase stimulation}, volume = 10, year = 2019 }

%0 Journal Article %1 mercier2019conserved %A Mercier, Rebecca %A Wolmarans, Annemarie %A Schubert, Jonathan %A Neuweiler, Hannes %A Johnson, Jill L. %A LaPointe, Paul %D 2019 %J Nature Communications %N 1 %P 1273-- %R 10.1038/s41467-019-09299-3 %T The conserved NxNNWHW motif in Aha-type co-chaperones modulates the kinetics of Hsp90 ATPase stimulation %U https://doi.org/10.1038/s41467-019-09299-3 %V 10 %X Hsp90 is a dimeric molecular chaperone that is essential for the folding and activation of hundreds of client proteins. Co-chaperone proteins regulate the ATP-driven Hsp90 client activation cycle. Aha-type co-chaperones are the most potent stimulators of the Hsp90 ATPase activity but the relationship between ATPase regulation and in vivo activity is poorly understood. We report here that the most strongly conserved region of Aha-type co-chaperones, the N terminal NxNNWHW motif, modulates the apparent affinity of Hsp90 for nucleotide substrates. The ability of yeast Aha-type co-chaperones to act in vivo is ablated when the N terminal NxNNWHW motif is removed. This work suggests that nucleotide exchange during the Hsp90 functional cycle may be more important than rate of catalysis.
Nanogels Enable Efficient miRNA Delivery and Target Gene Downregulation in Transfection-Resistant Multiple Myeloma Cells Zilkowski, Ilona; Ziouti, Fani; Schulze, Andres; Hauck, Stefanie; Schmidt, Stefanie; Mainz, Laura; Sauer, Markus; Albrecht, Krystyna; Jundt, Franziska; Groll, Jürgen in Biomacromolecules (2019). 20(2) 916–926.
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Multiple myeloma is a common plasma-cell-derived hematologic neoplasm. While the delivery of growth-inhibiting miRNA to multiple myeloma cells would be a promising strategy to evaluate treatment options, most multiple myeloma cells are transfection-resistant with established methods. Nonviral nanoparticulate transfection systems are particularly promising in this context, but so far struggle with transfection and knockdown efficiency. Here, we present poly(glycidol)-based nanogels with covalently bound cell-penetrating peptide TAT (transactivator of transcription from HIV). TAT facilitated a varying internalization efficiency of the nanogels depending on the cell line. The positively charged peptide also served as complexation agent for miRNA and enabled covalent binding of the TAT/miR-34a complex in the nanogels. These TAT/miRNA-loaded nanogels delivered and released miR-34a with high efficiency into OPM-2 multiple myeloma cells that are known as transfection-resistant. Delivery resulted in efficient downregulation of known target genes such as Notch1, Hey1, Hes6, and Hes1. Thus, these nanogel constructs offer a new tool to enhance gene delivery into multiple myeloma cells with immediate value in cancer research.

@article{zilkowski2019nanogels, abstract = {Multiple myeloma is a common plasma-cell-derived hematologic neoplasm. While the delivery of growth-inhibiting miRNA to multiple myeloma cells would be a promising strategy to evaluate treatment options, most multiple myeloma cells are transfection-resistant with established methods. Nonviral nanoparticulate transfection systems are particularly promising in this context, but so far struggle with transfection and knockdown efficiency. Here, we present poly(glycidol)-based nanogels with covalently bound cell-penetrating peptide TAT (transactivator of transcription from HIV). TAT facilitated a varying internalization efficiency of the nanogels depending on the cell line. The positively charged peptide also served as complexation agent for miRNA and enabled covalent binding of the TAT/miR-34a complex in the nanogels. These TAT/miRNA-loaded nanogels delivered and released miR-34a with high efficiency into OPM-2 multiple myeloma cells that are known as transfection-resistant. Delivery resulted in efficient downregulation of known target genes such as Notch1, Hey1, Hes6, and Hes1. Thus, these nanogel constructs offer a new tool to enhance gene delivery into multiple myeloma cells with immediate value in cancer research.}, author = {Zilkowski, Ilona and Ziouti, Fani and Schulze, Andres and Hauck, Stefanie and Schmidt, Stefanie and Mainz, Laura and Sauer, Markus and Albrecht, Krystyna and Jundt, Franziska and Groll, Jürgen}, booktitle = {Biomacromolecules}, journal = {Biomacromolecules}, keywords = {sauer}, month = {feb}, number = 2, pages = {916–926}, publisher = {American Chemical Society}, title = {Nanogels Enable Efficient miRNA Delivery and Target Gene Downregulation in Transfection-Resistant Multiple Myeloma Cells}, volume = 20, year = 2019 }

%0 Journal Article %1 zilkowski2019nanogels %A Zilkowski, Ilona %A Ziouti, Fani %A Schulze, Andres %A Hauck, Stefanie %A Schmidt, Stefanie %A Mainz, Laura %A Sauer, Markus %A Albrecht, Krystyna %A Jundt, Franziska %A Groll, Jürgen %B Biomacromolecules %D 2019 %I American Chemical Society %J Biomacromolecules %N 2 %P 916--926 %R 10.1021/acs.biomac.8b01553 %T Nanogels Enable Efficient miRNA Delivery and Target Gene Downregulation in Transfection-Resistant Multiple Myeloma Cells %U https://doi.org/10.1021/acs.biomac.8b01553 %V 20 %X Multiple myeloma is a common plasma-cell-derived hematologic neoplasm. While the delivery of growth-inhibiting miRNA to multiple myeloma cells would be a promising strategy to evaluate treatment options, most multiple myeloma cells are transfection-resistant with established methods. Nonviral nanoparticulate transfection systems are particularly promising in this context, but so far struggle with transfection and knockdown efficiency. Here, we present poly(glycidol)-based nanogels with covalently bound cell-penetrating peptide TAT (transactivator of transcription from HIV). TAT facilitated a varying internalization efficiency of the nanogels depending on the cell line. The positively charged peptide also served as complexation agent for miRNA and enabled covalent binding of the TAT/miR-34a complex in the nanogels. These TAT/miRNA-loaded nanogels delivered and released miR-34a with high efficiency into OPM-2 multiple myeloma cells that are known as transfection-resistant. Delivery resulted in efficient downregulation of known target genes such as Notch1, Hey1, Hes6, and Hes1. Thus, these nanogel constructs offer a new tool to enhance gene delivery into multiple myeloma cells with immediate value in cancer research.
Generation of site-distinct N-glycan variants for in vitro bioactivity testing Brühlmann, David; Vuillemin, Thomas; Satwekar, Abhijeet; Galano, Eugenio; Palmese, Angelo; D’Angelo, Alessandra; Manco, Zeynep; Souquet, Jonathan; Broly, Hervé; Sauer, Markus; Hemberger, Jürgen; Jordan, Martin in Biotechnology and Bioengineering (2019). 116(5) 1017–1028.
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Abstract Glycosylation, a critical product quality attribute, may affect the efficacy and safety of therapeutic proteins in vivo. Chinese hamster ovary fed-batch cell culture batches yielded consistent glycoprofiles of a Fc-fusion antibody comprizing three different N-glycosylation sites. By adding media supplements at specific concentrations in cell culture and applying enzymatic glycoengineering, a diverse N-glycan variant population was generated, including high mannose, afucosylated, fucosylated, agalactosylated, galactosylated, asialylated, and sialylated forms. Site-specific glycosylation profiles were elucidated by glycopeptide mapping and the effect of the glycosylation variants on the Fc?RIIIa receptor binding affinity and the biological activity (cell-based and surface plasmon resonance) was assessed. The two fusion body glycosylation sites were characterized by a high degree of sialic acid, more complex N-glycan structures, a higher degree of antennarity, and a site-specific behavior in the presence of a media supplement. On the other hand, the media supplements affected the Fc-site glycosylation heterogeneity similarly to the various studies described in the literature with classical monoclonal antibodies. Enzymatic glycoengineering solely managed to generate high levels of galactosylation at the fusion body sites. Variants with low core fucosylation, and to a lower extent, high mannose glycans exhibited increased Fc?RIIIa receptor binding affinity. All N-glycan variants exhibited weak effects on the biological activity of the fusion body. Both media supplementation and enzymatic glycoengineering are suitable to generate sufficient diversity to assess the effect of glycostructures on the biological activity.

@article{bruhlmann2019generation, abstract = {Abstract Glycosylation, a critical product quality attribute, may affect the efficacy and safety of therapeutic proteins in vivo. Chinese hamster ovary fed-batch cell culture batches yielded consistent glycoprofiles of a Fc-fusion antibody comprizing three different N-glycosylation sites. By adding media supplements at specific concentrations in cell culture and applying enzymatic glycoengineering, a diverse N-glycan variant population was generated, including high mannose, afucosylated, fucosylated, agalactosylated, galactosylated, asialylated, and sialylated forms. Site-specific glycosylation profiles were elucidated by glycopeptide mapping and the effect of the glycosylation variants on the Fc?RIIIa receptor binding affinity and the biological activity (cell-based and surface plasmon resonance) was assessed. The two fusion body glycosylation sites were characterized by a high degree of sialic acid, more complex N-glycan structures, a higher degree of antennarity, and a site-specific behavior in the presence of a media supplement. On the other hand, the media supplements affected the Fc-site glycosylation heterogeneity similarly to the various studies described in the literature with classical monoclonal antibodies. Enzymatic glycoengineering solely managed to generate high levels of galactosylation at the fusion body sites. Variants with low core fucosylation, and to a lower extent, high mannose glycans exhibited increased Fc?RIIIa receptor binding affinity. All N-glycan variants exhibited weak effects on the biological activity of the fusion body. Both media supplementation and enzymatic glycoengineering are suitable to generate sufficient diversity to assess the effect of glycostructures on the biological activity.}, author = {Brühlmann, David and Vuillemin, Thomas and Satwekar, Abhijeet and Galano, Eugenio and Palmese, Angelo and D'Angelo, Alessandra and Manco, Zeynep and Souquet, Jonathan and Broly, Hervé and Sauer, Markus and Hemberger, Jürgen and Jordan, Martin}, booktitle = {Biotechnology and Bioengineering}, journal = {Biotechnology and Bioengineering}, keywords = {sauer}, month = {may}, number = 5, pages = {1017–1028}, publisher = {John Wiley & Sons, Ltd}, title = {Generation of site-distinct N-glycan variants for in vitro bioactivity testing}, volume = 116, year = 2019 }

%0 Journal Article %1 bruhlmann2019generation %A Brühlmann, David %A Vuillemin, Thomas %A Satwekar, Abhijeet %A Galano, Eugenio %A Palmese, Angelo %A D'Angelo, Alessandra %A Manco, Zeynep %A Souquet, Jonathan %A Broly, Hervé %A Sauer, Markus %A Hemberger, Jürgen %A Jordan, Martin %B Biotechnology and Bioengineering %D 2019 %I John Wiley & Sons, Ltd %J Biotechnology and Bioengineering %N 5 %P 1017--1028 %R 10.1002/bit.26930 %T Generation of site-distinct N-glycan variants for in vitro bioactivity testing %U https://doi.org/10.1002/bit.26930 %V 116 %X Abstract Glycosylation, a critical product quality attribute, may affect the efficacy and safety of therapeutic proteins in vivo. Chinese hamster ovary fed-batch cell culture batches yielded consistent glycoprofiles of a Fc-fusion antibody comprizing three different N-glycosylation sites. By adding media supplements at specific concentrations in cell culture and applying enzymatic glycoengineering, a diverse N-glycan variant population was generated, including high mannose, afucosylated, fucosylated, agalactosylated, galactosylated, asialylated, and sialylated forms. Site-specific glycosylation profiles were elucidated by glycopeptide mapping and the effect of the glycosylation variants on the Fc?RIIIa receptor binding affinity and the biological activity (cell-based and surface plasmon resonance) was assessed. The two fusion body glycosylation sites were characterized by a high degree of sialic acid, more complex N-glycan structures, a higher degree of antennarity, and a site-specific behavior in the presence of a media supplement. On the other hand, the media supplements affected the Fc-site glycosylation heterogeneity similarly to the various studies described in the literature with classical monoclonal antibodies. Enzymatic glycoengineering solely managed to generate high levels of galactosylation at the fusion body sites. Variants with low core fucosylation, and to a lower extent, high mannose glycans exhibited increased Fc?RIIIa receptor binding affinity. All N-glycan variants exhibited weak effects on the biological activity of the fusion body. Both media supplementation and enzymatic glycoengineering are suitable to generate sufficient diversity to assess the effect of glycostructures on the biological activity.
Opsin 1 and Opsin 2 of the Corn Smut Fungus Ustilago maydis Are Green Light-Driven Proton Pumps Panzer, Sabine; Brych, Annika; Batschauer, Alfred; Terpitz, Ulrich in Frontiers in Microbiology (2019). 10
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In fungi green light is absorbed by rhodopsins, opsin proteins carrying a retinal molecule as chromophore. The basidiomycete Ustilago maydis, a fungal pathogen that infects corn plants, encodes three putative photoactive opsins, called ops1 (UMAG_02629), ops2 (UMAG_00371) and ops3 (UMAG_04125). UmOps1 and UmOps2 are expressed during the whole life cycle, in axenic cultures as well as in planta, whereas UmOps3 was recently shown to be absent in axenic cultures but highly expressed during plant infection. Here we show that expression of UmOps1 and UmOps2 is induced by blue light under control of White Collar 1 (Wco1). UmOps1 is mainly localized in the plasma membrane, both when expressed in HEK cells and U. maydis sporidia. In contrast, UmOps2 was mostly found intracellularly in the membranes of vacuoles. Patch-clamp studies demonstrated that both rhodopsins are green light-driven outward rectifying proton pumps. UmOps1 revealed an extraordinary pH dependency with increased activity in more acidic environment. Also, UmOps1 showed a pronounced, concentration-dependent enhancement of pump current caused by weak organic acids, especially by acetic acid and indole-3-acetic acid. In contrast, UmOps2 showed the typical behavior of light-driven, outwardly directed proton pumps, whereas UmOps3 did not exhibit any electrogenity. With this work, insights were gained into the localization and molecular function of two U. maydis rhodopsins, paving the way for further studies on the biological role of these rhodopsins in the life cycle of U. maydis.

@article{panzer2019opsin, abstract = {In fungi green light is absorbed by rhodopsins, opsin proteins carrying a retinal molecule as chromophore. The basidiomycete Ustilago maydis, a fungal pathogen that infects corn plants, encodes three putative photoactive opsins, called ops1 (UMAG_02629), ops2 (UMAG_00371) and ops3 (UMAG_04125). UmOps1 and UmOps2 are expressed during the whole life cycle, in axenic cultures as well as in planta, whereas UmOps3 was recently shown to be absent in axenic cultures but highly expressed during plant infection. Here we show that expression of UmOps1 and UmOps2 is induced by blue light under control of White Collar 1 (Wco1). UmOps1 is mainly localized in the plasma membrane, both when expressed in HEK cells and U. maydis sporidia. In contrast, UmOps2 was mostly found intracellularly in the membranes of vacuoles. Patch-clamp studies demonstrated that both rhodopsins are green light-driven outward rectifying proton pumps. UmOps1 revealed an extraordinary pH dependency with increased activity in more acidic environment. Also, UmOps1 showed a pronounced, concentration-dependent enhancement of pump current caused by weak organic acids, especially by acetic acid and indole-3-acetic acid. In contrast, UmOps2 showed the typical behavior of light-driven, outwardly directed proton pumps, whereas UmOps3 did not exhibit any electrogenity. With this work, insights were gained into the localization and molecular function of two U. maydis rhodopsins, paving the way for further studies on the biological role of these rhodopsins in the life cycle of U. maydis.}, author = {Panzer, Sabine and Brych, Annika and Batschauer, Alfred and Terpitz, Ulrich}, journal = {Frontiers in Microbiology}, keywords = {terpitz}, series = 735, title = {Opsin 1 and Opsin 2 of the Corn Smut Fungus Ustilago maydis Are Green Light-Driven Proton Pumps}, volume = 10, year = 2019 }

%0 Journal Article %1 panzer2019opsin %A Panzer, Sabine %A Brych, Annika %A Batschauer, Alfred %A Terpitz, Ulrich %B 735 %D 2019 %J Frontiers in Microbiology %T Opsin 1 and Opsin 2 of the Corn Smut Fungus Ustilago maydis Are Green Light-Driven Proton Pumps %U https://www.frontiersin.org/article/10.3389/fmicb.2019.00735 %V 10 %X In fungi green light is absorbed by rhodopsins, opsin proteins carrying a retinal molecule as chromophore. The basidiomycete Ustilago maydis, a fungal pathogen that infects corn plants, encodes three putative photoactive opsins, called ops1 (UMAG_02629), ops2 (UMAG_00371) and ops3 (UMAG_04125). UmOps1 and UmOps2 are expressed during the whole life cycle, in axenic cultures as well as in planta, whereas UmOps3 was recently shown to be absent in axenic cultures but highly expressed during plant infection. Here we show that expression of UmOps1 and UmOps2 is induced by blue light under control of White Collar 1 (Wco1). UmOps1 is mainly localized in the plasma membrane, both when expressed in HEK cells and U. maydis sporidia. In contrast, UmOps2 was mostly found intracellularly in the membranes of vacuoles. Patch-clamp studies demonstrated that both rhodopsins are green light-driven outward rectifying proton pumps. UmOps1 revealed an extraordinary pH dependency with increased activity in more acidic environment. Also, UmOps1 showed a pronounced, concentration-dependent enhancement of pump current caused by weak organic acids, especially by acetic acid and indole-3-acetic acid. In contrast, UmOps2 showed the typical behavior of light-driven, outwardly directed proton pumps, whereas UmOps3 did not exhibit any electrogenity. With this work, insights were gained into the localization and molecular function of two U. maydis rhodopsins, paving the way for further studies on the biological role of these rhodopsins in the life cycle of U. maydis.
Targeting GABAAR-Associated Proteins: New Modulators, Labels and Concepts Khayenko, Vladimir; Maric, Hans Michael in Frontiers in Molecular Neuroscience (2019). 12 162-.
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γ-aminobutyric acid type A receptors (GABAARs) are the major mediators of synaptic inhibition in the brain. Aberrant GABAAR activity or regulation is observed in various neurodevelopmental disorders, neurodegenerative diseases and mental illnesses, including epilepsy, Alzheimer’s and schizophrenia. Benzodiazepines, anesthetics and other pharmaceutics targeting these receptors find broad clinical use, but their inherent lack of receptor subtype specificity causes unavoidable side effects, raising a need for new or adjuvant medications. In this review we introduce a new strategy to modulate GABAeric signaling: Targeting the intracellular protein interactors of GABAARs. Of special interest are scaffolding, anchoring and supporting proteins that display high GABAAR subtype specificity. Recent efforts to target gephyrin, the major intracellular integrator of GABAergic signaling, confirm that GABAAR-associated proteins can be successfully targeted through diverse molecules, including recombinant proteins, intrabodies, peptide-based probes and small molecules. Small-molecule artemisinins and peptides derived from endogenous interactors, that specifically target the universal receptor binding site of gephyrin, acutely affect synaptic GABAAR numbers and clustering, modifying neuronal transmission. Interference with GABAAR trafficking provides another way to modulate inhibitory signaling. Peptides blocking the binding site of GABAAR to AP2 increase the surface concentration of GABAAR clusters and enhance GABAergic signaling. Engineering of gephyrin binding peptides delivered superior means to interrogate neuronal structure and function. Fluorescent peptides, designed from gephyrin binders, enable live neuronal staining and visualization of gephyrin in the post synaptic sites with nanometer resolution. We anticipate that in the future, novel fluorescent probes, with improved size and binding efficiency, may find wide application in super resolution microscopy studies, enlightening the nanoscale architecture of the inhibitory synapse. Broader studies on GABAAR accessory proteins and the identification of the exact molecular binding interfaces and affinities will advance the development of novel GABAAR modulators and following in-vivo studies will reveal their clinical potential as adjuvant or stand-alone drugs.

@article{khayenko2019targeting, abstract = {γ-aminobutyric acid type A receptors (GABAARs) are the major mediators of synaptic inhibition in the brain. Aberrant GABAAR activity or regulation is observed in various neurodevelopmental disorders, neurodegenerative diseases and mental illnesses, including epilepsy, Alzheimer’s and schizophrenia. Benzodiazepines, anesthetics and other pharmaceutics targeting these receptors find broad clinical use, but their inherent lack of receptor subtype specificity causes unavoidable side effects, raising a need for new or adjuvant medications. In this review we introduce a new strategy to modulate GABAeric signaling: Targeting the intracellular protein interactors of GABAARs. Of special interest are scaffolding, anchoring and supporting proteins that display high GABAAR subtype specificity. Recent efforts to target gephyrin, the major intracellular integrator of GABAergic signaling, confirm that GABAAR-associated proteins can be successfully targeted through diverse molecules, including recombinant proteins, intrabodies, peptide-based probes and small molecules. Small-molecule artemisinins and peptides derived from endogenous interactors, that specifically target the universal receptor binding site of gephyrin, acutely affect synaptic GABAAR numbers and clustering, modifying neuronal transmission. Interference with GABAAR trafficking provides another way to modulate inhibitory signaling. Peptides blocking the binding site of GABAAR to AP2 increase the surface concentration of GABAAR clusters and enhance GABAergic signaling. Engineering of gephyrin binding peptides delivered superior means to interrogate neuronal structure and function. Fluorescent peptides, designed from gephyrin binders, enable live neuronal staining and visualization of gephyrin in the post synaptic sites with nanometer resolution. We anticipate that in the future, novel fluorescent probes, with improved size and binding efficiency, may find wide application in super resolution microscopy studies, enlightening the nanoscale architecture of the inhibitory synapse. Broader studies on GABAAR accessory proteins and the identification of the exact molecular binding interfaces and affinities will advance the development of novel GABAAR modulators and following in-vivo studies will reveal their clinical potential as adjuvant or stand-alone drugs.}, author = {Khayenko, Vladimir and Maric, Hans Michael}, journal = {Frontiers in Molecular Neuroscience}, keywords = {maric}, pages = {162–}, title = {Targeting GABAAR-Associated Proteins: New Modulators, Labels and Concepts}, volume = 12, year = 2019 }

%0 Journal Article %1 khayenko2019targeting %A Khayenko, Vladimir %A Maric, Hans Michael %D 2019 %J Frontiers in Molecular Neuroscience %P 162-- %T Targeting GABAAR-Associated Proteins: New Modulators, Labels and Concepts %U https://www.frontiersin.org/article/10.3389/fnmol.2019.00162 %V 12 %X γ-aminobutyric acid type A receptors (GABAARs) are the major mediators of synaptic inhibition in the brain. Aberrant GABAAR activity or regulation is observed in various neurodevelopmental disorders, neurodegenerative diseases and mental illnesses, including epilepsy, Alzheimer’s and schizophrenia. Benzodiazepines, anesthetics and other pharmaceutics targeting these receptors find broad clinical use, but their inherent lack of receptor subtype specificity causes unavoidable side effects, raising a need for new or adjuvant medications. In this review we introduce a new strategy to modulate GABAeric signaling: Targeting the intracellular protein interactors of GABAARs. Of special interest are scaffolding, anchoring and supporting proteins that display high GABAAR subtype specificity. Recent efforts to target gephyrin, the major intracellular integrator of GABAergic signaling, confirm that GABAAR-associated proteins can be successfully targeted through diverse molecules, including recombinant proteins, intrabodies, peptide-based probes and small molecules. Small-molecule artemisinins and peptides derived from endogenous interactors, that specifically target the universal receptor binding site of gephyrin, acutely affect synaptic GABAAR numbers and clustering, modifying neuronal transmission. Interference with GABAAR trafficking provides another way to modulate inhibitory signaling. Peptides blocking the binding site of GABAAR to AP2 increase the surface concentration of GABAAR clusters and enhance GABAergic signaling. Engineering of gephyrin binding peptides delivered superior means to interrogate neuronal structure and function. Fluorescent peptides, designed from gephyrin binders, enable live neuronal staining and visualization of gephyrin in the post synaptic sites with nanometer resolution. We anticipate that in the future, novel fluorescent probes, with improved size and binding efficiency, may find wide application in super resolution microscopy studies, enlightening the nanoscale architecture of the inhibitory synapse. Broader studies on GABAAR accessory proteins and the identification of the exact molecular binding interfaces and affinities will advance the development of novel GABAAR modulators and following in-vivo studies will reveal their clinical potential as adjuvant or stand-alone drugs.
Neisseria meningitidis Type IV Pili Trigger Ca2+-Dependent Lysosomal Trafficking of the Acid Sphingomyelinase To Enhance Surface Ceramide Levels Peters, Simon; Schlegel, Jan; Becam, Jérôme; Avota, Elita; Sauer, Markus; Schubert-Unkmeir, Alexandra in Infect. Immun., (A. J. Bäumler, Hrsg.) (2019). 87(8) e00410–19.
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Acid sphingomyelinase (ASM) is a lipid hydrolase that converts sphingomyelin to ceramide and that can be activated by various cellular stress mechanisms, including bacterial pathogens. Vesicle transportation or trafficking of ASM from the lysosomal compartment to the cell membrane is a prerequisite for its activation in response to bacterial infections; however, the effectors and mechanisms of ASM translocation and activation are poorly defined. Our recent work documented the key importance of ASM for Neisseria meningitidis uptake into human brain microvascular endothelial cells (HBMEC). We clearly identified OpcA to be one bacterial effector promoting ASM translocation and activity, though it became clear that additional bacterial components were involved, as up to 80% of ASM activity and ceramide generation was retained in cells infected with an opcA-deficient mutant. We hypothesized that N. meningitidis might use pilus components to promote the translocation of ASM into HBMEC. Indeed, we found that both live, piliated N. meningitidis and pilus-enriched fractions trigger transient ASM surface display, followed by the formation of ceramide-rich platforms (CRPs). By using indirect immunocytochemistry and direct stochastic optical reconstruction microscopy, we show that the overall number of CRPs with a size of ∼80 nm in the plasma membrane is significantly increased after exposure to pilus-enriched fractions. Infection with live bacteria as well as exposure to pilus-enriched fractions transiently increased cytosolic Ca2+ levels in HBMEC, and this was found to be important for ASM surface display mediated by lysosomal exocytosis, as depletion of cytosolic Ca2+ resulted in a significant decrease in ASM surface levels, ASM activity, and CRP formation.

@article{peters2019ltspan, abstract = {Acid sphingomyelinase (ASM) is a lipid hydrolase that converts sphingomyelin to ceramide and that can be activated by various cellular stress mechanisms, including bacterial pathogens. Vesicle transportation or trafficking of ASM from the lysosomal compartment to the cell membrane is a prerequisite for its activation in response to bacterial infections; however, the effectors and mechanisms of ASM translocation and activation are poorly defined. Our recent work documented the key importance of ASM for Neisseria meningitidis uptake into human brain microvascular endothelial cells (HBMEC). We clearly identified OpcA to be one bacterial effector promoting ASM translocation and activity, though it became clear that additional bacterial components were involved, as up to 80% of ASM activity and ceramide generation was retained in cells infected with an opcA-deficient mutant. We hypothesized that N. meningitidis might use pilus components to promote the translocation of ASM into HBMEC. Indeed, we found that both live, piliated N. meningitidis and pilus-enriched fractions trigger transient ASM surface display, followed by the formation of ceramide-rich platforms (CRPs). By using indirect immunocytochemistry and direct stochastic optical reconstruction microscopy, we show that the overall number of CRPs with a size of ∼80 nm in the plasma membrane is significantly increased after exposure to pilus-enriched fractions. Infection with live bacteria as well as exposure to pilus-enriched fractions transiently increased cytosolic Ca2+ levels in HBMEC, and this was found to be important for ASM surface display mediated by lysosomal exocytosis, as depletion of cytosolic Ca2+ resulted in a significant decrease in ASM surface levels, ASM activity, and CRP formation.}, author = {Peters, Simon and Schlegel, Jan and Becam, Jérôme and Avota, Elita and Sauer, Markus and Schubert-Unkmeir, Alexandra}, editor = {Bäumler, Andreas J.}, journal = {Infect. Immun.}, keywords = {sauer}, month = {aug}, number = 8, pages = {e00410-19–}, title = {Neisseria meningitidis Type IV Pili Trigger Ca2+-Dependent Lysosomal Trafficking of the Acid Sphingomyelinase To Enhance Surface Ceramide Levels}, volume = 87, year = 2019 }

%0 Journal Article %1 peters2019ltspan %A Peters, Simon %A Schlegel, Jan %A Becam, Jérôme %A Avota, Elita %A Sauer, Markus %A Schubert-Unkmeir, Alexandra %D 2019 %E Bäumler, Andreas J. %J Infect. Immun. %N 8 %P e00410-19-- %R 10.1128/IAI.00410-19 %T Neisseria meningitidis Type IV Pili Trigger Ca2+-Dependent Lysosomal Trafficking of the Acid Sphingomyelinase To Enhance Surface Ceramide Levels %U http://iai.asm.org/content/87/8/e00410-19.abstract %V 87 %X Acid sphingomyelinase (ASM) is a lipid hydrolase that converts sphingomyelin to ceramide and that can be activated by various cellular stress mechanisms, including bacterial pathogens. Vesicle transportation or trafficking of ASM from the lysosomal compartment to the cell membrane is a prerequisite for its activation in response to bacterial infections; however, the effectors and mechanisms of ASM translocation and activation are poorly defined. Our recent work documented the key importance of ASM for Neisseria meningitidis uptake into human brain microvascular endothelial cells (HBMEC). We clearly identified OpcA to be one bacterial effector promoting ASM translocation and activity, though it became clear that additional bacterial components were involved, as up to 80% of ASM activity and ceramide generation was retained in cells infected with an opcA-deficient mutant. We hypothesized that N. meningitidis might use pilus components to promote the translocation of ASM into HBMEC. Indeed, we found that both live, piliated N. meningitidis and pilus-enriched fractions trigger transient ASM surface display, followed by the formation of ceramide-rich platforms (CRPs). By using indirect immunocytochemistry and direct stochastic optical reconstruction microscopy, we show that the overall number of CRPs with a size of ∼80 nm in the plasma membrane is significantly increased after exposure to pilus-enriched fractions. Infection with live bacteria as well as exposure to pilus-enriched fractions transiently increased cytosolic Ca2+ levels in HBMEC, and this was found to be important for ASM surface display mediated by lysosomal exocytosis, as depletion of cytosolic Ca2+ resulted in a significant decrease in ASM surface levels, ASM activity, and CRP formation.
MYC Recruits SPT5 to RNA Polymerase II to Promote Processive Transcription Elongation Baluapuri, Apoorva; Hofstetter, Julia; Dudvarski Stankovic, Nevenka; Endres, Theresa; Bhandare, Pranjali; Vos, Seychelle Monique; Adhikari, Bikash; Schwarz, Jessica Denise; Narain, Ashwin; Vogt, Markus; Wang, Shuang-Yan; Düster, Robert; Jung, Lisa Anna; Vanselow, Jens Thorsten; Wiegering, Armin; Geyer, Matthias; Maric, Hans Michael; Gallant, Peter; Walz, Susanne; Schlosser, Andreas; Cramer, Patrick; Eilers, Martin; Wolf, Elmar in Molecular Cell (2019). 74(4) 674–687.e11.
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Summary The MYC oncoprotein binds to promoter-proximal regions of virtually all transcribed genes and enhances RNA polymerase II (Pol II) function, but its precise mode of action is poorly understood. Using mass spectrometry of both MYC and Pol II complexes, we show here that MYC controls the assembly of Pol II with a small set of transcription elongation factors that includes SPT5, a subunit of the elongation factor DSIF. MYC directly binds SPT5, recruits SPT5 to promoters, and enables the CDK7-dependent transfer of SPT5 onto Pol II. Consistent with known functions of SPT5, MYC is required for fast and processive transcription elongation. Intriguingly, the high levels of MYC that are expressed in tumors sequester SPT5 into non-functional complexes, thereby decreasing the expression of growth-suppressive genes. Altogether, these results argue that MYC controls the productive assembly of processive Pol II elongation complexes and provide insight into how oncogenic levels of MYC permit uncontrolled cellular growth.

@article{baluapuri2019recruits, abstract = {Summary The MYC oncoprotein binds to promoter-proximal regions of virtually all transcribed genes and enhances RNA polymerase II (Pol II) function, but its precise mode of action is poorly understood. Using mass spectrometry of both MYC and Pol II complexes, we show here that MYC controls the assembly of Pol II with a small set of transcription elongation factors that includes SPT5, a subunit of the elongation factor DSIF. MYC directly binds SPT5, recruits SPT5 to promoters, and enables the CDK7-dependent transfer of SPT5 onto Pol II. Consistent with known functions of SPT5, MYC is required for fast and processive transcription elongation. Intriguingly, the high levels of MYC that are expressed in tumors sequester SPT5 into non-functional complexes, thereby decreasing the expression of growth-suppressive genes. Altogether, these results argue that MYC controls the productive assembly of processive Pol II elongation complexes and provide insight into how oncogenic levels of MYC permit uncontrolled cellular growth.}, author = {Baluapuri, Apoorva and Hofstetter, Julia and Dudvarski Stankovic, Nevenka and Endres, Theresa and Bhandare, Pranjali and Vos, Seychelle Monique and Adhikari, Bikash and Schwarz, Jessica Denise and Narain, Ashwin and Vogt, Markus and Wang, Shuang-Yan and Düster, Robert and Jung, Lisa Anna and Vanselow, Jens Thorsten and Wiegering, Armin and Geyer, Matthias and Maric, Hans Michael and Gallant, Peter and Walz, Susanne and Schlosser, Andreas and Cramer, Patrick and Eilers, Martin and Wolf, Elmar}, journal = {Molecular Cell}, keywords = {maric}, number = 4, pages = {674–687.e11}, title = {MYC Recruits SPT5 to RNA Polymerase II to Promote Processive Transcription Elongation}, volume = 74, year = 2019 }

%0 Journal Article %1 baluapuri2019recruits %A Baluapuri, Apoorva %A Hofstetter, Julia %A Dudvarski Stankovic, Nevenka %A Endres, Theresa %A Bhandare, Pranjali %A Vos, Seychelle Monique %A Adhikari, Bikash %A Schwarz, Jessica Denise %A Narain, Ashwin %A Vogt, Markus %A Wang, Shuang-Yan %A Düster, Robert %A Jung, Lisa Anna %A Vanselow, Jens Thorsten %A Wiegering, Armin %A Geyer, Matthias %A Maric, Hans Michael %A Gallant, Peter %A Walz, Susanne %A Schlosser, Andreas %A Cramer, Patrick %A Eilers, Martin %A Wolf, Elmar %D 2019 %J Molecular Cell %N 4 %P 674--687.e11 %R https://doi.org/10.1016/j.molcel.2019.02.031 %T MYC Recruits SPT5 to RNA Polymerase II to Promote Processive Transcription Elongation %U http://www.sciencedirect.com/science/article/pii/S109727651930142X %V 74 %X Summary The MYC oncoprotein binds to promoter-proximal regions of virtually all transcribed genes and enhances RNA polymerase II (Pol II) function, but its precise mode of action is poorly understood. Using mass spectrometry of both MYC and Pol II complexes, we show here that MYC controls the assembly of Pol II with a small set of transcription elongation factors that includes SPT5, a subunit of the elongation factor DSIF. MYC directly binds SPT5, recruits SPT5 to promoters, and enables the CDK7-dependent transfer of SPT5 onto Pol II. Consistent with known functions of SPT5, MYC is required for fast and processive transcription elongation. Intriguingly, the high levels of MYC that are expressed in tumors sequester SPT5 into non-functional complexes, thereby decreasing the expression of growth-suppressive genes. Altogether, these results argue that MYC controls the productive assembly of processive Pol II elongation complexes and provide insight into how oncogenic levels of MYC permit uncontrolled cellular growth.
Elucidating the Molecular Basis for Inhibitory Neurotransmission Regulation by Artemisinins Kasaragod, Vikram Babu; Hausrat, Torben Johann; Schaefer, Natascha; Kuhn, Maximilian; Christensen, Nikolaj Riis; Tessmer, Ingrid; Maric, Hans Michael; Madsen, Kenneth Lindegaard; Sotriffer, Christoph; Villmann, Carmen; Kneussel, Matthias; Schindelin, Hermann in Neuron (2019). 101(4) 673–689.e11.
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Summary The frontline anti-malarial drug artemisinin and its derivatives have also been implicated in modulating multiple mammalian cellular pathways, including the recent identification of targeting γ-aminobutyric acid type A receptor (GABAAR) signaling in the pancreas. Their molecular mechanism of action, however, remains elusive. Here, we present crystal structures of gephyrin, the central organizer at inhibitory postsynapses, in complex with artesunate and artemether at 1.5-Å resolution. These artemisinins target the universal inhibitory neurotransmitter receptor-binding epitope of gephyrin, thus inhibiting critical interactions between gephyrin and glycine receptors (GlyRs) as well as GABAARs. Electrophysiological recordings reveal a significant inhibition of gephyrin-mediated neurotransmission by artemisinins. Furthermore, clustering analyses in primary neurons demonstrate a rapid inhibition and a time-dependent regulation of gephyrin and GABAAR cluster parameters. Our data not only provide a comprehensive model for artemisinin-mediated modulation of inhibitory neurotransmission but also establish artemisinins as potential lead compounds to pharmacologically interfere with this process.

@article{kasaragod2019elucidating, abstract = {Summary The frontline anti-malarial drug artemisinin and its derivatives have also been implicated in modulating multiple mammalian cellular pathways, including the recent identification of targeting γ-aminobutyric acid type A receptor (GABAAR) signaling in the pancreas. Their molecular mechanism of action, however, remains elusive. Here, we present crystal structures of gephyrin, the central organizer at inhibitory postsynapses, in complex with artesunate and artemether at 1.5-Å resolution. These artemisinins target the universal inhibitory neurotransmitter receptor-binding epitope of gephyrin, thus inhibiting critical interactions between gephyrin and glycine receptors (GlyRs) as well as GABAARs. Electrophysiological recordings reveal a significant inhibition of gephyrin-mediated neurotransmission by artemisinins. Furthermore, clustering analyses in primary neurons demonstrate a rapid inhibition and a time-dependent regulation of gephyrin and GABAAR cluster parameters. Our data not only provide a comprehensive model for artemisinin-mediated modulation of inhibitory neurotransmission but also establish artemisinins as potential lead compounds to pharmacologically interfere with this process.}, author = {Kasaragod, Vikram Babu and Hausrat, Torben Johann and Schaefer, Natascha and Kuhn, Maximilian and Christensen, Nikolaj Riis and Tessmer, Ingrid and Maric, Hans Michael and Madsen, Kenneth Lindegaard and Sotriffer, Christoph and Villmann, Carmen and Kneussel, Matthias and Schindelin, Hermann}, journal = {Neuron}, keywords = {maric}, number = 4, pages = {673–689.e11}, title = {Elucidating the Molecular Basis for Inhibitory Neurotransmission Regulation by Artemisinins}, volume = 101, year = 2019 }

%0 Journal Article %1 kasaragod2019elucidating %A Kasaragod, Vikram Babu %A Hausrat, Torben Johann %A Schaefer, Natascha %A Kuhn, Maximilian %A Christensen, Nikolaj Riis %A Tessmer, Ingrid %A Maric, Hans Michael %A Madsen, Kenneth Lindegaard %A Sotriffer, Christoph %A Villmann, Carmen %A Kneussel, Matthias %A Schindelin, Hermann %D 2019 %J Neuron %N 4 %P 673--689.e11 %R https://doi.org/10.1016/j.neuron.2019.01.001 %T Elucidating the Molecular Basis for Inhibitory Neurotransmission Regulation by Artemisinins %U http://www.sciencedirect.com/science/article/pii/S0896627319300029 %V 101 %X Summary The frontline anti-malarial drug artemisinin and its derivatives have also been implicated in modulating multiple mammalian cellular pathways, including the recent identification of targeting γ-aminobutyric acid type A receptor (GABAAR) signaling in the pancreas. Their molecular mechanism of action, however, remains elusive. Here, we present crystal structures of gephyrin, the central organizer at inhibitory postsynapses, in complex with artesunate and artemether at 1.5-Å resolution. These artemisinins target the universal inhibitory neurotransmitter receptor-binding epitope of gephyrin, thus inhibiting critical interactions between gephyrin and glycine receptors (GlyRs) as well as GABAARs. Electrophysiological recordings reveal a significant inhibition of gephyrin-mediated neurotransmission by artemisinins. Furthermore, clustering analyses in primary neurons demonstrate a rapid inhibition and a time-dependent regulation of gephyrin and GABAAR cluster parameters. Our data not only provide a comprehensive model for artemisinin-mediated modulation of inhibitory neurotransmission but also establish artemisinins as potential lead compounds to pharmacologically interfere with this process.
MTHFD1 interaction with BRD4 links folate metabolism to transcriptional regulation Sdelci, Sara; Rendeiro, André F.; Rathert, Philipp; You, Wanhui; Lin, Jung-Ming G.; Ringler, Anna; Hofstätter, Gerald; Moll, Herwig P.; Gürtl, Bettina; Farlik, Matthias; Schick, Sandra; Klepsch, Freya; Oldach, Matthew; Buphamalai, Pisanu; Schischlik, Fiorella; Májek, Peter; Parapatics, Katja; Schmidl, Christian; Schuster, Michael; Penz, Thomas; Buckley, Dennis L.; Hudecz, Otto; Imre, Richard; Wang, Shuang-Yan; Maric, Hans Michael; Kralovics, Robert; Bennett, Keiryn L.; Müller, Andre C.; Mechtler, Karl; Menche, Jörg; Bradner, James E.; Winter, Georg E.; Klavins, Kristaps; Casanova, Emilio; Bock, Christoph; Zuber, Johannes; Kubicek, Stefan in Nature Genetics (2019). 51(6) 990–998.
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The histone acetyl reader bromodomain-containing protein 4 (BRD4) is an important regulator of chromatin structure and transcription, yet factors modulating its activity have remained elusive. Here we describe two complementary screens for genetic and physical interactors of BRD4, which converge on the folate pathway enzyme MTHFD1 (methylenetetrahydrofolate dehydrogenase, cyclohydrolase and formyltetrahydrofolate synthetase 1). We show that a fraction of MTHFD1 resides in the nucleus, where it is recruited to distinct genomic loci by direct interaction with BRD4. Inhibition of either BRD4 or MTHFD1 results in similar changes in nuclear metabolite composition and gene expression; pharmacological inhibitors of the two pathways synergize to impair cancer cell viability in vitro and in vivo. Our finding that MTHFD1 and other metabolic enzymes are chromatin associated suggests a direct role for nuclear metabolism in the control of gene expression.

@article{sdelci2019mthfd1, abstract = {The histone acetyl reader bromodomain-containing protein 4 (BRD4) is an important regulator of chromatin structure and transcription, yet factors modulating its activity have remained elusive. Here we describe two complementary screens for genetic and physical interactors of BRD4, which converge on the folate pathway enzyme MTHFD1 (methylenetetrahydrofolate dehydrogenase, cyclohydrolase and formyltetrahydrofolate synthetase 1). We show that a fraction of MTHFD1 resides in the nucleus, where it is recruited to distinct genomic loci by direct interaction with BRD4. Inhibition of either BRD4 or MTHFD1 results in similar changes in nuclear metabolite composition and gene expression; pharmacological inhibitors of the two pathways synergize to impair cancer cell viability in vitro and in vivo. Our finding that MTHFD1 and other metabolic enzymes are chromatin associated suggests a direct role for nuclear metabolism in the control of gene expression.}, author = {Sdelci, Sara and Rendeiro, André F. and Rathert, Philipp and You, Wanhui and Lin, Jung-Ming G. and Ringler, Anna and Hofstätter, Gerald and Moll, Herwig P. and Gürtl, Bettina and Farlik, Matthias and Schick, Sandra and Klepsch, Freya and Oldach, Matthew and Buphamalai, Pisanu and Schischlik, Fiorella and Májek, Peter and Parapatics, Katja and Schmidl, Christian and Schuster, Michael and Penz, Thomas and Buckley, Dennis L. and Hudecz, Otto and Imre, Richard and Wang, Shuang-Yan and Maric, Hans Michael and Kralovics, Robert and Bennett, Keiryn L. and Müller, Andre C. and Mechtler, Karl and Menche, Jörg and Bradner, James E. and Winter, Georg E. and Klavins, Kristaps and Casanova, Emilio and Bock, Christoph and Zuber, Johannes and Kubicek, Stefan}, journal = {Nature Genetics}, keywords = {maric}, number = 6, pages = {990–998}, title = {MTHFD1 interaction with BRD4 links folate metabolism to transcriptional regulation}, volume = 51, year = 2019 }

%0 Journal Article %1 sdelci2019mthfd1 %A Sdelci, Sara %A Rendeiro, André F. %A Rathert, Philipp %A You, Wanhui %A Lin, Jung-Ming G. %A Ringler, Anna %A Hofstätter, Gerald %A Moll, Herwig P. %A Gürtl, Bettina %A Farlik, Matthias %A Schick, Sandra %A Klepsch, Freya %A Oldach, Matthew %A Buphamalai, Pisanu %A Schischlik, Fiorella %A Májek, Peter %A Parapatics, Katja %A Schmidl, Christian %A Schuster, Michael %A Penz, Thomas %A Buckley, Dennis L. %A Hudecz, Otto %A Imre, Richard %A Wang, Shuang-Yan %A Maric, Hans Michael %A Kralovics, Robert %A Bennett, Keiryn L. %A Müller, Andre C. %A Mechtler, Karl %A Menche, Jörg %A Bradner, James E. %A Winter, Georg E. %A Klavins, Kristaps %A Casanova, Emilio %A Bock, Christoph %A Zuber, Johannes %A Kubicek, Stefan %D 2019 %J Nature Genetics %N 6 %P 990--998 %R 10.1038/s41588-019-0413-z %T MTHFD1 interaction with BRD4 links folate metabolism to transcriptional regulation %U https://doi.org/10.1038/s41588-019-0413-z %V 51 %X The histone acetyl reader bromodomain-containing protein 4 (BRD4) is an important regulator of chromatin structure and transcription, yet factors modulating its activity have remained elusive. Here we describe two complementary screens for genetic and physical interactors of BRD4, which converge on the folate pathway enzyme MTHFD1 (methylenetetrahydrofolate dehydrogenase, cyclohydrolase and formyltetrahydrofolate synthetase 1). We show that a fraction of MTHFD1 resides in the nucleus, where it is recruited to distinct genomic loci by direct interaction with BRD4. Inhibition of either BRD4 or MTHFD1 results in similar changes in nuclear metabolite composition and gene expression; pharmacological inhibitors of the two pathways synergize to impair cancer cell viability in vitro and in vivo. Our finding that MTHFD1 and other metabolic enzymes are chromatin associated suggests a direct role for nuclear metabolism in the control of gene expression.
Bioorthogonal labeling with tetrazine-dyes for super-resolution microscopy Beliu, Gerti; Kurz, Andreas J.; Kuhlemann, Alexander C.; Behringer-Pliess, Lisa; Meub, Mara; Wolf, Natalia; Seibel, Jürgen; Shi, Zhen-Dan; Schnermann, Martin; Grimm, Jonathan B.; Lavis, Luke D.; Doose, Sören; Sauer, Markus in Communications Biology (2019). 2(1) 261-.
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Genetic code expansion (GCE) technology allows the specific incorporation of functionalized noncanonical amino acids (ncAAs) into proteins. Here, we investigated the Diels-Alder reaction between trans-cyclooct-2-ene (TCO)-modified ncAAs, and 22 known and novel 1,2,4,5-tetrazine-dye conjugates spanning the entire visible wavelength range. A hallmark of this reaction is its fluorogenicity - the tetrazine moiety can elicit substantial quenching of the dye. We discovered that photoinduced electron transfer (PET) from the excited dye to tetrazine is the main quenching mechanism in red-absorbing oxazine and rhodamine derivatives. Upon reaction with dienophiles quenching interactions are reduced resulting in a considerable increase in fluorescence intensity. Efficient and specific labeling of all tetrazine-dyes investigated permits super-resolution microscopy with high signal-to-noise ratio even at the single-molecule level. The different cell permeability of tetrazine-dyes can be used advantageously for specific intra- and extracellular labeling of proteins and highly sensitive fluorescence imaging experiments in fixed and living cells.

@article{beliu2019bioorthogonal, abstract = {Genetic code expansion (GCE) technology allows the specific incorporation of functionalized noncanonical amino acids (ncAAs) into proteins. Here, we investigated the Diels-Alder reaction between trans-cyclooct-2-ene (TCO)-modified ncAAs, and 22 known and novel 1,2,4,5-tetrazine-dye conjugates spanning the entire visible wavelength range. A hallmark of this reaction is its fluorogenicity - the tetrazine moiety can elicit substantial quenching of the dye. We discovered that photoinduced electron transfer (PET) from the excited dye to tetrazine is the main quenching mechanism in red-absorbing oxazine and rhodamine derivatives. Upon reaction with dienophiles quenching interactions are reduced resulting in a considerable increase in fluorescence intensity. Efficient and specific labeling of all tetrazine-dyes investigated permits super-resolution microscopy with high signal-to-noise ratio even at the single-molecule level. The different cell permeability of tetrazine-dyes can be used advantageously for specific intra- and extracellular labeling of proteins and highly sensitive fluorescence imaging experiments in fixed and living cells.}, author = {Beliu, Gerti and Kurz, Andreas J. and Kuhlemann, Alexander C. and Behringer-Pliess, Lisa and Meub, Mara and Wolf, Natalia and Seibel, Jürgen and Shi, Zhen-Dan and Schnermann, Martin and Grimm, Jonathan B. and Lavis, Luke D. and Doose, Sören and Sauer, Markus}, journal = {Communications Biology}, keywords = {sauer}, number = 1, pages = {261–}, title = {Bioorthogonal labeling with tetrazine-dyes for super-resolution microscopy}, volume = 2, year = 2019 }

%0 Journal Article %1 beliu2019bioorthogonal %A Beliu, Gerti %A Kurz, Andreas J. %A Kuhlemann, Alexander C. %A Behringer-Pliess, Lisa %A Meub, Mara %A Wolf, Natalia %A Seibel, Jürgen %A Shi, Zhen-Dan %A Schnermann, Martin %A Grimm, Jonathan B. %A Lavis, Luke D. %A Doose, Sören %A Sauer, Markus %D 2019 %J Communications Biology %N 1 %P 261-- %R 10.1038/s42003-019-0518-z %T Bioorthogonal labeling with tetrazine-dyes for super-resolution microscopy %U https://doi.org/10.1038/s42003-019-0518-z %V 2 %X Genetic code expansion (GCE) technology allows the specific incorporation of functionalized noncanonical amino acids (ncAAs) into proteins. Here, we investigated the Diels-Alder reaction between trans-cyclooct-2-ene (TCO)-modified ncAAs, and 22 known and novel 1,2,4,5-tetrazine-dye conjugates spanning the entire visible wavelength range. A hallmark of this reaction is its fluorogenicity - the tetrazine moiety can elicit substantial quenching of the dye. We discovered that photoinduced electron transfer (PET) from the excited dye to tetrazine is the main quenching mechanism in red-absorbing oxazine and rhodamine derivatives. Upon reaction with dienophiles quenching interactions are reduced resulting in a considerable increase in fluorescence intensity. Efficient and specific labeling of all tetrazine-dyes investigated permits super-resolution microscopy with high signal-to-noise ratio even at the single-molecule level. The different cell permeability of tetrazine-dyes can be used advantageously for specific intra- and extracellular labeling of proteins and highly sensitive fluorescence imaging experiments in fixed and living cells.

2018[ to top ]

Sharpening emitter localization in front of a tuned mirror Heil, Hannah S.; Schreiber, Benjamin; Götz, Ralph; Emmerling, Monika; Dabauvalle, Marie-Christine; Krohne, Georg; Höfling, Sven; Kamp, Martin; Sauer, Markus; Heinze, Katrin G. in Light: Science & Applications (2018). 7(1) 99-.
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Single-molecule localization microscopy (SMLM) aims for maximized precision and a high signal-to-noise ratio1. Both features can be provided by placing the emitter in front of a metal-dielectric nanocoating that acts as a tuned mirror2–4. Here, we demonstrate that a higher photon yield at a lower background on biocompatible metal-dielectric nanocoatings substantially improves SMLM performance and increases the localization precision by up to a factor of two. The resolution improvement relies solely on easy-to-fabricate nanocoatings on standard glass coverslips and is spectrally and spatially tunable by the layer design and wavelength, as experimentally demonstrated for dual-color SMLM in cells.

@article{heil2018sharpening, abstract = {Single-molecule localization microscopy (SMLM) aims for maximized precision and a high signal-to-noise ratio1. Both features can be provided by placing the emitter in front of a metal-dielectric nanocoating that acts as a tuned mirror2–4. Here, we demonstrate that a higher photon yield at a lower background on biocompatible metal-dielectric nanocoatings substantially improves SMLM performance and increases the localization precision by up to a factor of two. The resolution improvement relies solely on easy-to-fabricate nanocoatings on standard glass coverslips and is spectrally and spatially tunable by the layer design and wavelength, as experimentally demonstrated for dual-color SMLM in cells.}, author = {Heil, Hannah S. and Schreiber, Benjamin and Götz, Ralph and Emmerling, Monika and Dabauvalle, Marie-Christine and Krohne, Georg and Höfling, Sven and Kamp, Martin and Sauer, Markus and Heinze, Katrin G.}, journal = {Light: Science & Applications}, keywords = {sauer}, number = 1, pages = {99–}, title = {Sharpening emitter localization in front of a tuned mirror}, volume = 7, year = 2018 }

%0 Journal Article %1 heil2018sharpening %A Heil, Hannah S. %A Schreiber, Benjamin %A Götz, Ralph %A Emmerling, Monika %A Dabauvalle, Marie-Christine %A Krohne, Georg %A Höfling, Sven %A Kamp, Martin %A Sauer, Markus %A Heinze, Katrin G. %D 2018 %J Light: Science & Applications %N 1 %P 99-- %R 10.1038/s41377-018-0104-z %T Sharpening emitter localization in front of a tuned mirror %U https://doi.org/10.1038/s41377-018-0104-z %V 7 %X Single-molecule localization microscopy (SMLM) aims for maximized precision and a high signal-to-noise ratio1. Both features can be provided by placing the emitter in front of a metal-dielectric nanocoating that acts as a tuned mirror2–4. Here, we demonstrate that a higher photon yield at a lower background on biocompatible metal-dielectric nanocoatings substantially improves SMLM performance and increases the localization precision by up to a factor of two. The resolution improvement relies solely on easy-to-fabricate nanocoatings on standard glass coverslips and is spectrally and spatially tunable by the layer design and wavelength, as experimentally demonstrated for dual-color SMLM in cells.
The Neutral Sphingomyelinase 2 Is Required to Polarize and Sustain T Cell Receptor Signaling Börtlein, Charlene; Draeger, Annette; Schoenauer, Roman; Kuhlemann, Alexander; Sauer, Markus; Schneider-Schaulies, Sibylle; Avota, Elita in Frontiers in Immunology (2018). 9 815-.
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By promoting ceramide release at the cytosolic membrane leaflet, the neutral sphingomyelinase 2 (NSM) is capable of organizing receptor and signalosome segregation. Its role in T cell receptor (TCR) signaling remained so far unknown. We now show that TCR-driven NSM activation is dispensable for TCR clustering and initial phosphorylation, but of crucial importance for further signal amplification. In particular, at low doses of TCR stimulatory antibodies, NSM is required for Ca2+ mobilization and T cell proliferation. NSM deficient T cells lack sustained CD3ζ and ZAP-70 phosphorylation and are unable to polarize and stabilize their microtubular system. We identified PKCζ as the key NSM downstream effector in this second wave of TCR signaling supporting dynamics of microtubule-organizing center (MTOC). Ceramide supplementation rescued PKCζ membrane recruitment and MTOC translocation in NSM deficient cells. These findings identify the NSM as essential in TCR signaling when dynamic cytoskeletal reorganization promotes continued lateral and vertical supply of TCR signaling components: CD3ζ, Zap70 and PKCζ, and functional immune synapses (IS) are organized and stabilized via MTOC polarization.

@article{bortlein2018neutral, abstract = {By promoting ceramide release at the cytosolic membrane leaflet, the neutral sphingomyelinase 2 (NSM) is capable of organizing receptor and signalosome segregation. Its role in T cell receptor (TCR) signaling remained so far unknown. We now show that TCR-driven NSM activation is dispensable for TCR clustering and initial phosphorylation, but of crucial importance for further signal amplification. In particular, at low doses of TCR stimulatory antibodies, NSM is required for Ca2+ mobilization and T cell proliferation. NSM deficient T cells lack sustained CD3ζ and ZAP-70 phosphorylation and are unable to polarize and stabilize their microtubular system. We identified PKCζ as the key NSM downstream effector in this second wave of TCR signaling supporting dynamics of microtubule-organizing center (MTOC). Ceramide supplementation rescued PKCζ membrane recruitment and MTOC translocation in NSM deficient cells. These findings identify the NSM as essential in TCR signaling when dynamic cytoskeletal reorganization promotes continued lateral and vertical supply of TCR signaling components: CD3ζ, Zap70 and PKCζ, and functional immune synapses (IS) are organized and stabilized via MTOC polarization.}, author = {Börtlein, Charlene and Draeger, Annette and Schoenauer, Roman and Kuhlemann, Alexander and Sauer, Markus and Schneider-Schaulies, Sibylle and Avota, Elita}, journal = {Frontiers in Immunology}, keywords = {sauer}, pages = {815–}, title = {The Neutral Sphingomyelinase 2 Is Required to Polarize and Sustain T Cell Receptor Signaling}, volume = 9, year = 2018 }

%0 Journal Article %1 bortlein2018neutral %A Börtlein, Charlene %A Draeger, Annette %A Schoenauer, Roman %A Kuhlemann, Alexander %A Sauer, Markus %A Schneider-Schaulies, Sibylle %A Avota, Elita %D 2018 %J Frontiers in Immunology %P 815-- %T The Neutral Sphingomyelinase 2 Is Required to Polarize and Sustain T Cell Receptor Signaling %U https://www.frontiersin.org/article/10.3389/fimmu.2018.00815 %V 9 %X By promoting ceramide release at the cytosolic membrane leaflet, the neutral sphingomyelinase 2 (NSM) is capable of organizing receptor and signalosome segregation. Its role in T cell receptor (TCR) signaling remained so far unknown. We now show that TCR-driven NSM activation is dispensable for TCR clustering and initial phosphorylation, but of crucial importance for further signal amplification. In particular, at low doses of TCR stimulatory antibodies, NSM is required for Ca2+ mobilization and T cell proliferation. NSM deficient T cells lack sustained CD3ζ and ZAP-70 phosphorylation and are unable to polarize and stabilize their microtubular system. We identified PKCζ as the key NSM downstream effector in this second wave of TCR signaling supporting dynamics of microtubule-organizing center (MTOC). Ceramide supplementation rescued PKCζ membrane recruitment and MTOC translocation in NSM deficient cells. These findings identify the NSM as essential in TCR signaling when dynamic cytoskeletal reorganization promotes continued lateral and vertical supply of TCR signaling components: CD3ζ, Zap70 and PKCζ, and functional immune synapses (IS) are organized and stabilized via MTOC polarization.
Bioorthogonal Click Chemistry Enables Site-specific Fluorescence Labeling of Functional NMDA Receptors for Super-Resolution Imaging Neubert, Franziska; Beliu, Gerti; Terpitz, Ulrich; Werner, Christian; Geis, Christian; Sauer, Markus; Doose, Sören in Angewandte Chemie International Edition (2018). 57(50) 16364–16369.
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Abstract Super-resolution microscopy requires small fluorescent labels. We report the application of genetic code expansion in combination with bioorthogonal click chemistry to label the NR1 domain of the NMDA receptor. We generated NR1 mutants incorporating an unnatural amino acid at various positions in order to attach small organic fluorophores such as Cy5-tetrazine site-specifically to the extracellular domain of the receptor. Mutants were optimized with regard to protein expression, labeling efficiency and receptor functionality as tested by fluorescence microscopy and whole-cell patch clamp. The results show that bioorthogonal click chemistry in combination with small organic dyes is superior to available immunocytochemistry protocols for receptor labeling in live and fixed cells and enables single-molecule sensitive super-resolution microscopy experiments.

@article{neubert2018bioorthogonal, abstract = {Abstract Super-resolution microscopy requires small fluorescent labels. We report the application of genetic code expansion in combination with bioorthogonal click chemistry to label the NR1 domain of the NMDA receptor. We generated NR1 mutants incorporating an unnatural amino acid at various positions in order to attach small organic fluorophores such as Cy5-tetrazine site-specifically to the extracellular domain of the receptor. Mutants were optimized with regard to protein expression, labeling efficiency and receptor functionality as tested by fluorescence microscopy and whole-cell patch clamp. The results show that bioorthogonal click chemistry in combination with small organic dyes is superior to available immunocytochemistry protocols for receptor labeling in live and fixed cells and enables single-molecule sensitive super-resolution microscopy experiments.}, author = {Neubert, Franziska and Beliu, Gerti and Terpitz, Ulrich and Werner, Christian and Geis, Christian and Sauer, Markus and Doose, Sören}, booktitle = {Angewandte Chemie International Edition}, journal = {Angewandte Chemie International Edition}, keywords = {werner}, month = {oct}, number = 50, pages = {16364–16369}, publisher = {John Wiley & Sons, Ltd}, title = {Bioorthogonal Click Chemistry Enables Site-specific Fluorescence Labeling of Functional NMDA Receptors for Super-Resolution Imaging}, volume = 57, year = 2018 }

%0 Journal Article %1 neubert2018bioorthogonal %A Neubert, Franziska %A Beliu, Gerti %A Terpitz, Ulrich %A Werner, Christian %A Geis, Christian %A Sauer, Markus %A Doose, Sören %B Angewandte Chemie International Edition %D 2018 %I John Wiley & Sons, Ltd %J Angewandte Chemie International Edition %N 50 %P 16364--16369 %R 10.1002/anie.201808951 %T Bioorthogonal Click Chemistry Enables Site-specific Fluorescence Labeling of Functional NMDA Receptors for Super-Resolution Imaging %U https://doi.org/10.1002/anie.201808951 %V 57 %X Abstract Super-resolution microscopy requires small fluorescent labels. We report the application of genetic code expansion in combination with bioorthogonal click chemistry to label the NR1 domain of the NMDA receptor. We generated NR1 mutants incorporating an unnatural amino acid at various positions in order to attach small organic fluorophores such as Cy5-tetrazine site-specifically to the extracellular domain of the receptor. Mutants were optimized with regard to protein expression, labeling efficiency and receptor functionality as tested by fluorescence microscopy and whole-cell patch clamp. The results show that bioorthogonal click chemistry in combination with small organic dyes is superior to available immunocytochemistry protocols for receptor labeling in live and fixed cells and enables single-molecule sensitive super-resolution microscopy experiments.
β Cell-specific deletion of guanylyl cyclase A, the receptor for atrial natriuretic peptide, accelerates obesity-induced glucose intolerance in mice Tauscher, Sabine; Nakagawa, Hitoshi; Völker, Katharina; Werner, Franziska; Krebes, Lisa; Potapenko, Tamara; Doose, Sören; Birkenfeld, Andreas L.; Baba, Hideo A.; Kuhn, Michaela in Cardiovascular Diabetology (2018). 17 103.
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The cardiac hormones atrial (ANP) and B-type natriuretic peptides (BNP) moderate arterial blood pressure and improve energy metabolism as well as insulin sensitivity via their shared cGMP-producing guanylyl cyclase-A (GC-A) receptor. Obesity is associated with impaired NP/GC-A/cGMP signaling, which possibly contributes to the development of type 2 diabetes and its cardiometabolic complications. In vitro, synthetic ANP, via GC-A, stimulates glucose-dependent insulin release from cultured pancreatic islets and β-cell proliferation. However, the relevance for systemic glucose homeostasis in vivo is not known. To dissect whether the endogenous cardiac hormones modulate the secretory function and/or proliferation of β-cells under (patho)physiological conditions in vivo, here we generated a novel genetic mouse model with selective disruption of the GC-A receptor in β-cells.

@article{tauscher2018cellspecific, abstract = {The cardiac hormones atrial (ANP) and B-type natriuretic peptides (BNP) moderate arterial blood pressure and improve energy metabolism as well as insulin sensitivity via their shared cGMP-producing guanylyl cyclase-A (GC-A) receptor. Obesity is associated with impaired NP/GC-A/cGMP signaling, which possibly contributes to the development of type 2 diabetes and its cardiometabolic complications. In vitro, synthetic ANP, via GC-A, stimulates glucose-dependent insulin release from cultured pancreatic islets and β-cell proliferation. However, the relevance for systemic glucose homeostasis in vivo is not known. To dissect whether the endogenous cardiac hormones modulate the secretory function and/or proliferation of β-cells under (patho)physiological conditions in vivo, here we generated a novel genetic mouse model with selective disruption of the GC-A receptor in β-cells.}, author = {Tauscher, Sabine and Nakagawa, Hitoshi and Völker, Katharina and Werner, Franziska and Krebes, Lisa and Potapenko, Tamara and Doose, Sören and Birkenfeld, Andreas L. and Baba, Hideo A. and Kuhn, Michaela}, journal = {Cardiovascular Diabetology}, keywords = {doose}, pages = 103, series = 1, title = {β Cell-specific deletion of guanylyl cyclase A, the receptor for atrial natriuretic peptide, accelerates obesity-induced glucose intolerance in mice}, volume = 17, year = 2018 }

%0 Journal Article %1 tauscher2018cellspecific %A Tauscher, Sabine %A Nakagawa, Hitoshi %A Völker, Katharina %A Werner, Franziska %A Krebes, Lisa %A Potapenko, Tamara %A Doose, Sören %A Birkenfeld, Andreas L. %A Baba, Hideo A. %A Kuhn, Michaela %B 1 %D 2018 %J Cardiovascular Diabetology %P 103 %T β Cell-specific deletion of guanylyl cyclase A, the receptor for atrial natriuretic peptide, accelerates obesity-induced glucose intolerance in mice %U https://doi.org/10.1186/s12933-018-0747-3 %V 17 %X The cardiac hormones atrial (ANP) and B-type natriuretic peptides (BNP) moderate arterial blood pressure and improve energy metabolism as well as insulin sensitivity via their shared cGMP-producing guanylyl cyclase-A (GC-A) receptor. Obesity is associated with impaired NP/GC-A/cGMP signaling, which possibly contributes to the development of type 2 diabetes and its cardiometabolic complications. In vitro, synthetic ANP, via GC-A, stimulates glucose-dependent insulin release from cultured pancreatic islets and β-cell proliferation. However, the relevance for systemic glucose homeostasis in vivo is not known. To dissect whether the endogenous cardiac hormones modulate the secretory function and/or proliferation of β-cells under (patho)physiological conditions in vivo, here we generated a novel genetic mouse model with selective disruption of the GC-A receptor in β-cells.
Two-step self-assembly of a spider silk molecular clamp Rat, Charlotte; Heiby, Julia C.; Bunz, Jessica P.; Neuweiler, Hannes in Nature Communications (2018). 9(1) 4779-.
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Web spiders synthesize silk fibers of unique strength and extensibility through the controlled self-assembly of protein building blocks, so-called spidroins. The spidroin C-terminal domain is highly conserved and connects two polypeptide chains through formation of an all-helical, intertwined dimer. Here we use contact-induced fluorescence self-quenching and resonance energy transfer in combination with far-UV circular dichroism spectroscopy as three orthogonal structural probes to dissect the mechanism of folding and dimerization of a spidroin C-terminal domain from the major ampullate gland of the nursery web spider Euprosthenops australis. We show that helices forming the dimer core assemble very rapidly and fold on association. Subsequently, peripheral helices fold and dock slowly onto the preformed core. Lability of outer helices facilitates formation of a highly expanded, partially folded dimer. The high end-to-end distance of chain termini in the partially folded dimer suggests an extensibility module that contributes to elasticity of spider silk.

@article{rat2018twostep, abstract = {Web spiders synthesize silk fibers of unique strength and extensibility through the controlled self-assembly of protein building blocks, so-called spidroins. The spidroin C-terminal domain is highly conserved and connects two polypeptide chains through formation of an all-helical, intertwined dimer. Here we use contact-induced fluorescence self-quenching and resonance energy transfer in combination with far-UV circular dichroism spectroscopy as three orthogonal structural probes to dissect the mechanism of folding and dimerization of a spidroin C-terminal domain from the major ampullate gland of the nursery web spider Euprosthenops australis. We show that helices forming the dimer core assemble very rapidly and fold on association. Subsequently, peripheral helices fold and dock slowly onto the preformed core. Lability of outer helices facilitates formation of a highly expanded, partially folded dimer. The high end-to-end distance of chain termini in the partially folded dimer suggests an extensibility module that contributes to elasticity of spider silk.}, author = {Rat, Charlotte and Heiby, Julia C. and Bunz, Jessica P. and Neuweiler, Hannes}, journal = {Nature Communications}, keywords = {hannes}, number = 1, pages = {4779–}, title = {Two-step self-assembly of a spider silk molecular clamp}, volume = 9, year = 2018 }

%0 Journal Article %1 rat2018twostep %A Rat, Charlotte %A Heiby, Julia C. %A Bunz, Jessica P. %A Neuweiler, Hannes %D 2018 %J Nature Communications %N 1 %P 4779-- %R 10.1038/s41467-018-07227-5 %T Two-step self-assembly of a spider silk molecular clamp %U https://doi.org/10.1038/s41467-018-07227-5 %V 9 %X Web spiders synthesize silk fibers of unique strength and extensibility through the controlled self-assembly of protein building blocks, so-called spidroins. The spidroin C-terminal domain is highly conserved and connects two polypeptide chains through formation of an all-helical, intertwined dimer. Here we use contact-induced fluorescence self-quenching and resonance energy transfer in combination with far-UV circular dichroism spectroscopy as three orthogonal structural probes to dissect the mechanism of folding and dimerization of a spidroin C-terminal domain from the major ampullate gland of the nursery web spider Euprosthenops australis. We show that helices forming the dimer core assemble very rapidly and fold on association. Subsequently, peripheral helices fold and dock slowly onto the preformed core. Lability of outer helices facilitates formation of a highly expanded, partially folded dimer. The high end-to-end distance of chain termini in the partially folded dimer suggests an extensibility module that contributes to elasticity of spider silk.
Nanostructure of DNA repair foci revealed by superresolution microscopy Sisario, Dmitri; Memmel, Simon; Doose, Sören; Neubauer, Julia; Zimmermann, Heiko; Flentje, Michael; Djuzenova, Cholpon S.; Sauer, Markus; Sukhorukov, Vladimir L. in The FASEB Journal (2018). fj.201701435-.
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Induction of DNA double-strand breaks (DSBs) by ionizing radiation leads to formation of micrometer-sized DNA-repair foci, whose organization on the nanometer-scale remains unknown because of the diffraction limit (?200 nm) of conventional microscopy. Here, we applied diffraction-unlimited, direct stochastic optical-reconstruction microscopy (dSTORM) with a lateral resolution of ?20 nm to analyze the focal nanostructure of the DSB marker histone ?H2AX and the DNA-repair protein kinase (DNA-PK) in irradiated glioblastoma multiforme cells. Although standard confocal microscopy revealed substantial colocalization of immunostained ?H2AX and DNA-PK, in our dSTORM images, the 2 proteins showed very little (if any) colocalization despite their close spatial proximity. We also found that ?H2AX foci consisted of distinct circular subunits (?nanofoci?) with a diameter of ?45 nm, whereas DNA-PK displayed a diffuse, intrafocal distribution. We conclude that ?H2AX nanofoci represent the elementary, structural units of DSB repair foci, that is, individual ?H2AX-containing nucleosomes. dSTORM-based ?H2AX nanofoci counting and distance measurements between nanofoci provided quantitative information on the total amount of chromatin involved in DSB repair as well as on the number and longitudinal distribution of ?H2AX-containing nucleosomes in a chromatin fiber. We thus estimate that a single focus involves between ?0.6 and ?1.1 Mbp of chromatin, depending on radiation treatment. Because of their ability to unravel the nanostructure of DSB-repair foci, dSTORM and related single-molecule localization nanoscopy methods will likely emerge as powerful tools in biology and medicine to elucidate the effects of DNA damaging agents in cells.?Sisario, D., Memmel, S., Doose, S., Neubauer, J., Zimmermann, H., Flentje, M., Djuzenova, C. S., Sauer, M., Sukhorukov, V. L. Nanostructure of DNA repair foci revealed by superresolution microscopy.

@article{sisario2018nanostructure, abstract = {Induction of DNA double-strand breaks (DSBs) by ionizing radiation leads to formation of micrometer-sized DNA-repair foci, whose organization on the nanometer-scale remains unknown because of the diffraction limit (?200 nm) of conventional microscopy. Here, we applied diffraction-unlimited, direct stochastic optical-reconstruction microscopy (dSTORM) with a lateral resolution of ?20 nm to analyze the focal nanostructure of the DSB marker histone ?H2AX and the DNA-repair protein kinase (DNA-PK) in irradiated glioblastoma multiforme cells. Although standard confocal microscopy revealed substantial colocalization of immunostained ?H2AX and DNA-PK, in our dSTORM images, the 2 proteins showed very little (if any) colocalization despite their close spatial proximity. We also found that ?H2AX foci consisted of distinct circular subunits (?nanofoci?) with a diameter of ?45 nm, whereas DNA-PK displayed a diffuse, intrafocal distribution. We conclude that ?H2AX nanofoci represent the elementary, structural units of DSB repair foci, that is, individual ?H2AX-containing nucleosomes. dSTORM-based ?H2AX nanofoci counting and distance measurements between nanofoci provided quantitative information on the total amount of chromatin involved in DSB repair as well as on the number and longitudinal distribution of ?H2AX-containing nucleosomes in a chromatin fiber. We thus estimate that a single focus involves between ?0.6 and ?1.1 Mbp of chromatin, depending on radiation treatment. Because of their ability to unravel the nanostructure of DSB-repair foci, dSTORM and related single-molecule localization nanoscopy methods will likely emerge as powerful tools in biology and medicine to elucidate the effects of DNA damaging agents in cells.?Sisario, D., Memmel, S., Doose, S., Neubauer, J., Zimmermann, H., Flentje, M., Djuzenova, C. S., Sauer, M., Sukhorukov, V. L. Nanostructure of DNA repair foci revealed by superresolution microscopy.}, author = {Sisario, Dmitri and Memmel, Simon and Doose, Sören and Neubauer, Julia and Zimmermann, Heiko and Flentje, Michael and Djuzenova, Cholpon S. and Sauer, Markus and Sukhorukov, Vladimir L.}, booktitle = {The FASEB Journal}, journal = {The FASEB Journal}, keywords = {vladimir}, month = {jun}, pages = {fj.201701435–}, publisher = {Federation of American Societies for Experimental Biology}, title = {Nanostructure of DNA repair foci revealed by superresolution microscopy}, year = 2018 }

%0 Journal Article %1 sisario2018nanostructure %A Sisario, Dmitri %A Memmel, Simon %A Doose, Sören %A Neubauer, Julia %A Zimmermann, Heiko %A Flentje, Michael %A Djuzenova, Cholpon S. %A Sauer, Markus %A Sukhorukov, Vladimir L. %B The FASEB Journal %D 2018 %I Federation of American Societies for Experimental Biology %J The FASEB Journal %P fj.201701435-- %R 10.1096/fj.201701435 %T Nanostructure of DNA repair foci revealed by superresolution microscopy %U https://doi.org/10.1096/fj.201701435 %X Induction of DNA double-strand breaks (DSBs) by ionizing radiation leads to formation of micrometer-sized DNA-repair foci, whose organization on the nanometer-scale remains unknown because of the diffraction limit (?200 nm) of conventional microscopy. Here, we applied diffraction-unlimited, direct stochastic optical-reconstruction microscopy (dSTORM) with a lateral resolution of ?20 nm to analyze the focal nanostructure of the DSB marker histone ?H2AX and the DNA-repair protein kinase (DNA-PK) in irradiated glioblastoma multiforme cells. Although standard confocal microscopy revealed substantial colocalization of immunostained ?H2AX and DNA-PK, in our dSTORM images, the 2 proteins showed very little (if any) colocalization despite their close spatial proximity. We also found that ?H2AX foci consisted of distinct circular subunits (?nanofoci?) with a diameter of ?45 nm, whereas DNA-PK displayed a diffuse, intrafocal distribution. We conclude that ?H2AX nanofoci represent the elementary, structural units of DSB repair foci, that is, individual ?H2AX-containing nucleosomes. dSTORM-based ?H2AX nanofoci counting and distance measurements between nanofoci provided quantitative information on the total amount of chromatin involved in DSB repair as well as on the number and longitudinal distribution of ?H2AX-containing nucleosomes in a chromatin fiber. We thus estimate that a single focus involves between ?0.6 and ?1.1 Mbp of chromatin, depending on radiation treatment. Because of their ability to unravel the nanostructure of DSB-repair foci, dSTORM and related single-molecule localization nanoscopy methods will likely emerge as powerful tools in biology and medicine to elucidate the effects of DNA damaging agents in cells.?Sisario, D., Memmel, S., Doose, S., Neubauer, J., Zimmermann, H., Flentje, M., Djuzenova, C. S., Sauer, M., Sukhorukov, V. L. Nanostructure of DNA repair foci revealed by superresolution microscopy.
MEK-inhibitor PD184352 enhances the radiosensitizing effect of the Hsp90 inhibitor NVP-AUY922: the role of cell type and drug-irradiation schedule Grabenbauer, Felix; Katzer, Astrid; Sisario, Dmitri; Memmel, Simon; Flentje, Michael; Sukhorukov, Vladimir L.; Djuzenova, Cholpon S. in Oncotarget (2018). 9 37379–37392.
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Targeting MEK protein in cancer cells usually leads to acquired resistance to MEK inhibitors and activation of the prosurvival protein Akt. Since both MEK and Akt are clients of the Hsp90 chaperone system, the present study explores the responses of irradiated lung carcinoma A549 and glioblastoma SNB19 cell lines to combined MEK and Hsp90 inhibition. Unexpectedly, the MEK inhibitor PD184352 administered 24 h prior to irradiation, enhanced cell survival through upregulation of not only MEK and Erk1/2 but also of Akt. In contrast, PD184352 added 1 h before irradiation strongly reduced the expression of Erk and did not upregulate Akt in both cell lines. As a result, the MEK inhibitor increased the radiosensitizing effect of the Hsp90 inhibitor NVP-AUY922 in glioblastoma SNB19 cells. Possible reasons for the enhanced cell killing under this short-term pretreatment schedule may be a down-regulation of Erk during or directly after irradiation, increased DNA damage and/or a strong G2/M arrest 24 h after irradiation. In addition, an 1-h pretreatment with PD184352 and/or NVP-AUY922 under schedule II induced neither G1 arrest nor up-regulation of p-Akt in both cell lines as it did under schedule I. Yet, a long-term treatment with the MEK inhibitor alone caused a strong cytostatical effect. We conclude that the duration of drug pretreatment before irradiation plays a key role in the targeting of MEK in tumor cells. However, due to an aberrant activation of prosurvival proteins, the therapeutic window needs to be carefully defined, or a combination of inhibitors should be considered.

@article{grabenbauer2018mekinhibitor, abstract = {Targeting MEK protein in cancer cells usually leads to acquired resistance to MEK inhibitors and activation of the prosurvival protein Akt. Since both MEK and Akt are clients of the Hsp90 chaperone system, the present study explores the responses of irradiated lung carcinoma A549 and glioblastoma SNB19 cell lines to combined MEK and Hsp90 inhibition. Unexpectedly, the MEK inhibitor PD184352 administered 24 h prior to irradiation, enhanced cell survival through upregulation of not only MEK and Erk1/2 but also of Akt. In contrast, PD184352 added 1 h before irradiation strongly reduced the expression of Erk and did not upregulate Akt in both cell lines. As a result, the MEK inhibitor increased the radiosensitizing effect of the Hsp90 inhibitor NVP-AUY922 in glioblastoma SNB19 cells. Possible reasons for the enhanced cell killing under this short-term pretreatment schedule may be a down-regulation of Erk during or directly after irradiation, increased DNA damage and/or a strong G2/M arrest 24 h after irradiation. In addition, an 1-h pretreatment with PD184352 and/or NVP-AUY922 under schedule II induced neither G1 arrest nor up-regulation of p-Akt in both cell lines as it did under schedule I. Yet, a long-term treatment with the MEK inhibitor alone caused a strong cytostatical effect. We conclude that the duration of drug pretreatment before irradiation plays a key role in the targeting of MEK in tumor cells. However, due to an aberrant activation of prosurvival proteins, the therapeutic window needs to be carefully defined, or a combination of inhibitors should be considered.}, author = {Grabenbauer, Felix and Katzer, Astrid and Sisario, Dmitri and Memmel, Simon and Flentje, Michael and Sukhorukov, Vladimir L. and Djuzenova, Cholpon S.}, journal = {Oncotarget}, keywords = {vladimir}, pages = {37379-37392}, title = {MEK-inhibitor PD184352 enhances the radiosensitizing effect of the Hsp90 inhibitor NVP-AUY922: the role of cell type and drug-irradiation schedule}, volume = 9, year = 2018 }

%0 Journal Article %1 grabenbauer2018mekinhibitor %A Grabenbauer, Felix %A Katzer, Astrid %A Sisario, Dmitri %A Memmel, Simon %A Flentje, Michael %A Sukhorukov, Vladimir L. %A Djuzenova, Cholpon S. %D 2018 %J Oncotarget %P 37379-37392 %T MEK-inhibitor PD184352 enhances the radiosensitizing effect of the Hsp90 inhibitor NVP-AUY922: the role of cell type and drug-irradiation schedule %U https://doi.org/10.18632/oncotarget.26436 %V 9 %X Targeting MEK protein in cancer cells usually leads to acquired resistance to MEK inhibitors and activation of the prosurvival protein Akt. Since both MEK and Akt are clients of the Hsp90 chaperone system, the present study explores the responses of irradiated lung carcinoma A549 and glioblastoma SNB19 cell lines to combined MEK and Hsp90 inhibition. Unexpectedly, the MEK inhibitor PD184352 administered 24 h prior to irradiation, enhanced cell survival through upregulation of not only MEK and Erk1/2 but also of Akt. In contrast, PD184352 added 1 h before irradiation strongly reduced the expression of Erk and did not upregulate Akt in both cell lines. As a result, the MEK inhibitor increased the radiosensitizing effect of the Hsp90 inhibitor NVP-AUY922 in glioblastoma SNB19 cells. Possible reasons for the enhanced cell killing under this short-term pretreatment schedule may be a down-regulation of Erk during or directly after irradiation, increased DNA damage and/or a strong G2/M arrest 24 h after irradiation. In addition, an 1-h pretreatment with PD184352 and/or NVP-AUY922 under schedule II induced neither G1 arrest nor up-regulation of p-Akt in both cell lines as it did under schedule I. Yet, a long-term treatment with the MEK inhibitor alone caused a strong cytostatical effect. We conclude that the duration of drug pretreatment before irradiation plays a key role in the targeting of MEK in tumor cells. However, due to an aberrant activation of prosurvival proteins, the therapeutic window needs to be carefully defined, or a combination of inhibitors should be considered.
Protein Activity of the Fusarium fujikuroi Rhodopsins CarO and OpsA and Their Relation to Fungus–Plant Interaction Adam, Alexander; Deimel, Stephan; Pardo-Medina, Javier; García-Martínez, Jorge; Konte, Tilen; Limón, M.; Avalos, Javier; Terpitz, Ulrich in International Journal of Molecular Sciences (2018). 19 215.
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Fungi possess diverse photosensory proteins that allow them to perceive different light wavelengths and to adapt to changing light conditions in their environment. The biological and physiological roles of the green light-sensing rhodopsins in fungi are not yet resolved. The rice plant pathogen Fusarium fujikuroi exhibits two different rhodopsins, CarO and OpsA. CarO was previously characterized as a light-driven proton pump. We further analyzed the pumping behavior of CarO by patch-clamp experiments. Our data show that CarO pumping activity is strongly augmented in the presence of the plant hormone indole-3-acetic acid and in sodium acetate, in a dose-dependent manner under slightly acidic conditions. By contrast, under these and other tested conditions, the Neurospora rhodopsin (NR)-like rhodopsin OpsA did not exhibit any pump activity. Basic local alignment search tool (BLAST) searches in the genomes of ascomycetes revealed the occurrence of rhodopsin-encoding genes mainly in phyto-associated or phytopathogenic fungi, suggesting a possible correlation of the presence of rhodopsins with fungal ecology. In accordance, rice plants infected with a CarO-deficient F. fujikuroi strain showed more severe bakanae symptoms than the reference strain, indicating a potential role of the CarO rhodopsin in the regulation of plant infection by this fungus.

@article{adam2018protein, abstract = {Fungi possess diverse photosensory proteins that allow them to perceive different light wavelengths and to adapt to changing light conditions in their environment. The biological and physiological roles of the green light-sensing rhodopsins in fungi are not yet resolved. The rice plant pathogen Fusarium fujikuroi exhibits two different rhodopsins, CarO and OpsA. CarO was previously characterized as a light-driven proton pump. We further analyzed the pumping behavior of CarO by patch-clamp experiments. Our data show that CarO pumping activity is strongly augmented in the presence of the plant hormone indole-3-acetic acid and in sodium acetate, in a dose-dependent manner under slightly acidic conditions. By contrast, under these and other tested conditions, the Neurospora rhodopsin (NR)-like rhodopsin OpsA did not exhibit any pump activity. Basic local alignment search tool (BLAST) searches in the genomes of ascomycetes revealed the occurrence of rhodopsin-encoding genes mainly in phyto-associated or phytopathogenic fungi, suggesting a possible correlation of the presence of rhodopsins with fungal ecology. In accordance, rice plants infected with a CarO-deficient F. fujikuroi strain showed more severe bakanae symptoms than the reference strain, indicating a potential role of the CarO rhodopsin in the regulation of plant infection by this fungus.}, author = {Adam, Alexander and Deimel, Stephan and Pardo-Medina, Javier and García-Martínez, Jorge and Konte, Tilen and Limón, M. and Avalos, Javier and Terpitz, Ulrich}, journal = {International Journal of Molecular Sciences}, keywords = {terpitz}, pages = 215, series = 1, title = {Protein Activity of the Fusarium fujikuroi Rhodopsins CarO and OpsA and Their Relation to Fungus–Plant Interaction}, volume = 19, year = 2018 }

%0 Journal Article %1 adam2018protein %A Adam, Alexander %A Deimel, Stephan %A Pardo-Medina, Javier %A García-Martínez, Jorge %A Konte, Tilen %A Limón, M. %A Avalos, Javier %A Terpitz, Ulrich %B 1 %D 2018 %J International Journal of Molecular Sciences %P 215 %T Protein Activity of the Fusarium fujikuroi Rhodopsins CarO and OpsA and Their Relation to Fungus–Plant Interaction %U http://www.mdpi.com/1422-0067/19/1/215 %V 19 %X Fungi possess diverse photosensory proteins that allow them to perceive different light wavelengths and to adapt to changing light conditions in their environment. The biological and physiological roles of the green light-sensing rhodopsins in fungi are not yet resolved. The rice plant pathogen Fusarium fujikuroi exhibits two different rhodopsins, CarO and OpsA. CarO was previously characterized as a light-driven proton pump. We further analyzed the pumping behavior of CarO by patch-clamp experiments. Our data show that CarO pumping activity is strongly augmented in the presence of the plant hormone indole-3-acetic acid and in sodium acetate, in a dose-dependent manner under slightly acidic conditions. By contrast, under these and other tested conditions, the Neurospora rhodopsin (NR)-like rhodopsin OpsA did not exhibit any pump activity. Basic local alignment search tool (BLAST) searches in the genomes of ascomycetes revealed the occurrence of rhodopsin-encoding genes mainly in phyto-associated or phytopathogenic fungi, suggesting a possible correlation of the presence of rhodopsins with fungal ecology. In accordance, rice plants infected with a CarO-deficient F. fujikuroi strain showed more severe bakanae symptoms than the reference strain, indicating a potential role of the CarO rhodopsin in the regulation of plant infection by this fungus.
HyphaTracker: An ImageJ toolbox for time-resolved analysis of spore germination in filamentous fungi Brunk, Michael; Sputh, Sebastian; Doose, Sören; van de Linde, Sebastian; Terpitz, Ulrich in Scientific Reports (2018). 8(1) 605-.
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The dynamics of early fungal development and its interference with physiological signals and environmental factors is yet poorly understood. Especially computational analysis tools for the evaluation of the process of early spore germination and germ tube formation are still lacking. For the time-resolved analysis of conidia germination of the filamentous ascomycete Fusarium fujikuroi we developed a straightforward toolbox implemented in ImageJ. It allows for processing of microscopic acquisitions (movies) of conidial germination starting with drift correction and data reduction prior to germling analysis. From the image time series germling related region of interests (ROIs) are extracted, which are analysed for their area, circularity, and timing. ROIs originating from germlings crossing other hyphae or the image boundaries are omitted during analysis. Each conidium/hypha is identified and related to its origin, thus allowing subsequent categorization. The efficiency of HyphaTracker was proofed and the accuracy was tested on simulated germlings at different signal-to-noise ratios. Bright-field microscopic images of conidial germination of rhodopsin-deficient F. fujikuroi mutants and their respective control strains were analysed with HyphaTracker. Consistent with our observation in earlier studies the CarO deficient mutant germinated earlier and grew faster than other, CarO expressing strains.

@article{brunk2018hyphatracker, abstract = {The dynamics of early fungal development and its interference with physiological signals and environmental factors is yet poorly understood. Especially computational analysis tools for the evaluation of the process of early spore germination and germ tube formation are still lacking. For the time-resolved analysis of conidia germination of the filamentous ascomycete Fusarium fujikuroi we developed a straightforward toolbox implemented in ImageJ. It allows for processing of microscopic acquisitions (movies) of conidial germination starting with drift correction and data reduction prior to germling analysis. From the image time series germling related region of interests (ROIs) are extracted, which are analysed for their area, circularity, and timing. ROIs originating from germlings crossing other hyphae or the image boundaries are omitted during analysis. Each conidium/hypha is identified and related to its origin, thus allowing subsequent categorization. The efficiency of HyphaTracker was proofed and the accuracy was tested on simulated germlings at different signal-to-noise ratios. Bright-field microscopic images of conidial germination of rhodopsin-deficient F. fujikuroi mutants and their respective control strains were analysed with HyphaTracker. Consistent with our observation in earlier studies the CarO deficient mutant germinated earlier and grew faster than other, CarO expressing strains.}, author = {Brunk, Michael and Sputh, Sebastian and Doose, Sören and van de Linde, Sebastian and Terpitz, Ulrich}, journal = {Scientific Reports}, keywords = {terpitz}, number = 1, pages = {605–}, title = {HyphaTracker: An ImageJ toolbox for time-resolved analysis of spore germination in filamentous fungi}, volume = 8, year = 2018 }

%0 Journal Article %1 brunk2018hyphatracker %A Brunk, Michael %A Sputh, Sebastian %A Doose, Sören %A van de Linde, Sebastian %A Terpitz, Ulrich %D 2018 %J Scientific Reports %N 1 %P 605-- %R 10.1038/s41598-017-19103-1 %T HyphaTracker: An ImageJ toolbox for time-resolved analysis of spore germination in filamentous fungi %U https://doi.org/10.1038/s41598-017-19103-1 %V 8 %X The dynamics of early fungal development and its interference with physiological signals and environmental factors is yet poorly understood. Especially computational analysis tools for the evaluation of the process of early spore germination and germ tube formation are still lacking. For the time-resolved analysis of conidia germination of the filamentous ascomycete Fusarium fujikuroi we developed a straightforward toolbox implemented in ImageJ. It allows for processing of microscopic acquisitions (movies) of conidial germination starting with drift correction and data reduction prior to germling analysis. From the image time series germling related region of interests (ROIs) are extracted, which are analysed for their area, circularity, and timing. ROIs originating from germlings crossing other hyphae or the image boundaries are omitted during analysis. Each conidium/hypha is identified and related to its origin, thus allowing subsequent categorization. The efficiency of HyphaTracker was proofed and the accuracy was tested on simulated germlings at different signal-to-noise ratios. Bright-field microscopic images of conidial germination of rhodopsin-deficient F. fujikuroi mutants and their respective control strains were analysed with HyphaTracker. Consistent with our observation in earlier studies the CarO deficient mutant germinated earlier and grew faster than other, CarO expressing strains.
Human Autoantibodies against the AMPA Receptor Subunit GluA2 Induce Receptor Reorganization and Memory Dysfunction Haselmann, Holger; Mannara, Francesco; Werner, Christian; Planagumà, Jesús; Miguez-Cabello, Federico; Schmidl, Lars; Grünewald, Benedikt; Petit-Pedrol, Mar; Kirmse, Knut; Classen, Joseph; Demir, Fatih; Klöcker, Nikolaj; Soto, David; Doose, Sören; Dalmau, Josep; Hallermann, Stefan; Geis, Christian in Neuron (2018). 100(1) 91–105.e9.
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AMPA receptors are essential for fast excitatory transmission in the CNS. Autoantibodies to AMPA receptors have been identified in humans with autoimmune encephalitis and severe defects of hippocampal function. Here, combining electrophysiology and high-resolution imaging with neuronal culture preparations and passive-transfer models in wild-type and GluA1-knockout mice, we analyze how specific human autoantibodies against the AMPA receptor subunit GluA2 affect receptor function and composition, synaptic transmission, and plasticity. Anti-GluA2 antibodies induce receptor internalization and a reduction of synaptic GluA2-containing AMPARs followed by compensatory ryanodine receptor-dependent incorporation of synaptic non-GluA2 AMPARs. Furthermore, application of human pathogenic anti-GluA2 antibodies to mice impairs long-term synaptic plasticity in vitro and affects learning and memory in vivo. Our results identify a specific immune-neuronal rearrangement of AMPA receptor subunits, providing a framework to explain disease symptoms.

@article{haselmann2018human, abstract = {AMPA receptors are essential for fast excitatory transmission in the CNS. Autoantibodies to AMPA receptors have been identified in humans with autoimmune encephalitis and severe defects of hippocampal function. Here, combining electrophysiology and high-resolution imaging with neuronal culture preparations and passive-transfer models in wild-type and GluA1-knockout mice, we analyze how specific human autoantibodies against the AMPA receptor subunit GluA2 affect receptor function and composition, synaptic transmission, and plasticity. Anti-GluA2 antibodies induce receptor internalization and a reduction of synaptic GluA2-containing AMPARs followed by compensatory ryanodine receptor-dependent incorporation of synaptic non-GluA2 AMPARs. Furthermore, application of human pathogenic anti-GluA2 antibodies to mice impairs long-term synaptic plasticity in vitro and affects learning and memory in vivo. Our results identify a specific immune-neuronal rearrangement of AMPA receptor subunits, providing a framework to explain disease symptoms.}, author = {Haselmann, Holger and Mannara, Francesco and Werner, Christian and Planagumà, Jesús and Miguez-Cabello, Federico and Schmidl, Lars and Grünewald, Benedikt and Petit-Pedrol, Mar and Kirmse, Knut and Classen, Joseph and Demir, Fatih and Klöcker, Nikolaj and Soto, David and Doose, Sören and Dalmau, Josep and Hallermann, Stefan and Geis, Christian}, journal = {Neuron}, keywords = {werner}, number = 1, pages = {91–105.e9}, title = {Human Autoantibodies against the AMPA Receptor Subunit GluA2 Induce Receptor Reorganization and Memory Dysfunction}, volume = 100, year = 2018 }

%0 Journal Article %1 haselmann2018human %A Haselmann, Holger %A Mannara, Francesco %A Werner, Christian %A Planagumà, Jesús %A Miguez-Cabello, Federico %A Schmidl, Lars %A Grünewald, Benedikt %A Petit-Pedrol, Mar %A Kirmse, Knut %A Classen, Joseph %A Demir, Fatih %A Klöcker, Nikolaj %A Soto, David %A Doose, Sören %A Dalmau, Josep %A Hallermann, Stefan %A Geis, Christian %D 2018 %J Neuron %N 1 %P 91--105.e9 %R https://doi.org/10.1016/j.neuron.2018.07.048 %T Human Autoantibodies against the AMPA Receptor Subunit GluA2 Induce Receptor Reorganization and Memory Dysfunction %U http://www.sciencedirect.com/science/article/pii/S0896627318306469 %V 100 %X AMPA receptors are essential for fast excitatory transmission in the CNS. Autoantibodies to AMPA receptors have been identified in humans with autoimmune encephalitis and severe defects of hippocampal function. Here, combining electrophysiology and high-resolution imaging with neuronal culture preparations and passive-transfer models in wild-type and GluA1-knockout mice, we analyze how specific human autoantibodies against the AMPA receptor subunit GluA2 affect receptor function and composition, synaptic transmission, and plasticity. Anti-GluA2 antibodies induce receptor internalization and a reduction of synaptic GluA2-containing AMPARs followed by compensatory ryanodine receptor-dependent incorporation of synaptic non-GluA2 AMPARs. Furthermore, application of human pathogenic anti-GluA2 antibodies to mice impairs long-term synaptic plasticity in vitro and affects learning and memory in vivo. Our results identify a specific immune-neuronal rearrangement of AMPA receptor subunits, providing a framework to explain disease symptoms.
Protein Engineering Reveals Mechanisms of Functional Amyloid Formation in Pseudomonas aeruginosa Biofilms Bleem, Alissa; Christiansen, Gunna; Madsen, Daniel J.; Maric, Hans; Strømgaard, Kristian; Bryers, James D.; Daggett, Valerie; Meyer, Rikke L.; Otzen, Daniel E. in Journal of Molecular Biology (2018). 430(20) 3751–3763.
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Amyloids are typically associated with neurodegenerative diseases, but recent research demonstrates that several bacteria utilize functional amyloid fibrils to fortify the biofilm extracellular matrix and thereby resist antibiotic treatments. In Pseudomonas aeruginosa, these fibrils are composed predominantly of FapC, a protein with high-sequence conservation among the genera. Previous studies established FapC as the major amyloid subunit, but its mechanism of fibril formation in P. aeruginosa remained largely unexplored. Here, we examine the FapC sequence in greater detail through a combination of bioinformatics and protein engineering, and we identify specific motifs that are implicated in amyloid formation. Sequence regions of high evolutionary conservation tend to coincide with regions of high amyloid propensity, and mutation of amyloidogenic motifs to a designed, non-amyloidogenic motif suppresses fibril formation in a pH-dependent manner. We establish the particular significance of the third repeat motif in promoting fibril formation and also demonstrate emergence of soluble oligomer species early in the aggregation pathway. The insights reported here expand our understanding of the mechanism of amyloid polymerization in P. aeruginosa, laying the foundation for development of new amyloid inhibitors to combat recalcitrant biofilm infections.

@article{bleem2018protein, abstract = {Amyloids are typically associated with neurodegenerative diseases, but recent research demonstrates that several bacteria utilize functional amyloid fibrils to fortify the biofilm extracellular matrix and thereby resist antibiotic treatments. In Pseudomonas aeruginosa, these fibrils are composed predominantly of FapC, a protein with high-sequence conservation among the genera. Previous studies established FapC as the major amyloid subunit, but its mechanism of fibril formation in P. aeruginosa remained largely unexplored. Here, we examine the FapC sequence in greater detail through a combination of bioinformatics and protein engineering, and we identify specific motifs that are implicated in amyloid formation. Sequence regions of high evolutionary conservation tend to coincide with regions of high amyloid propensity, and mutation of amyloidogenic motifs to a designed, non-amyloidogenic motif suppresses fibril formation in a pH-dependent manner. We establish the particular significance of the third repeat motif in promoting fibril formation and also demonstrate emergence of soluble oligomer species early in the aggregation pathway. The insights reported here expand our understanding of the mechanism of amyloid polymerization in P. aeruginosa, laying the foundation for development of new amyloid inhibitors to combat recalcitrant biofilm infections.}, author = {Bleem, Alissa and Christiansen, Gunna and Madsen, Daniel J. and Maric, Hans and Strømgaard, Kristian and Bryers, James D. and Daggett, Valerie and Meyer, Rikke L. and Otzen, Daniel E.}, booktitle = {Functional Amyloids in Health and Disease}, journal = {Journal of Molecular Biology}, keywords = {maric}, number = 20, pages = {3751–3763}, title = {Protein Engineering Reveals Mechanisms of Functional Amyloid Formation in Pseudomonas aeruginosa Biofilms}, volume = 430, year = 2018 }

%0 Journal Article %1 bleem2018protein %A Bleem, Alissa %A Christiansen, Gunna %A Madsen, Daniel J. %A Maric, Hans %A Strømgaard, Kristian %A Bryers, James D. %A Daggett, Valerie %A Meyer, Rikke L. %A Otzen, Daniel E. %B Functional Amyloids in Health and Disease %D 2018 %J Journal of Molecular Biology %N 20 %P 3751--3763 %R https://doi.org/10.1016/j.jmb.2018.06.043 %T Protein Engineering Reveals Mechanisms of Functional Amyloid Formation in Pseudomonas aeruginosa Biofilms %U http://www.sciencedirect.com/science/article/pii/S0022283618307046 %V 430 %X Amyloids are typically associated with neurodegenerative diseases, but recent research demonstrates that several bacteria utilize functional amyloid fibrils to fortify the biofilm extracellular matrix and thereby resist antibiotic treatments. In Pseudomonas aeruginosa, these fibrils are composed predominantly of FapC, a protein with high-sequence conservation among the genera. Previous studies established FapC as the major amyloid subunit, but its mechanism of fibril formation in P. aeruginosa remained largely unexplored. Here, we examine the FapC sequence in greater detail through a combination of bioinformatics and protein engineering, and we identify specific motifs that are implicated in amyloid formation. Sequence regions of high evolutionary conservation tend to coincide with regions of high amyloid propensity, and mutation of amyloidogenic motifs to a designed, non-amyloidogenic motif suppresses fibril formation in a pH-dependent manner. We establish the particular significance of the third repeat motif in promoting fibril formation and also demonstrate emergence of soluble oligomer species early in the aggregation pathway. The insights reported here expand our understanding of the mechanism of amyloid polymerization in P. aeruginosa, laying the foundation for development of new amyloid inhibitors to combat recalcitrant biofilm infections.
Developmental seizures and mortality result from reducing GABAA receptor α2-subunit interaction with collybistin Hines, Rochelle M.; Maric, Hans Michael; Hines, Dustin J.; Modgil, Amit; Panzanelli, Patrizia; Nakamura, Yasuko; Nathanson, Anna J.; Cross, Alan; Deeb, Tarek; Brandon, Nicholas J.; Davies, Paul; Fritschy, Jean-Marc; Schindelin, Hermann; Moss, Stephen J. in Nature Communications (2018). 9(1) 3130-.
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Fast inhibitory synaptic transmission is mediated by γ-aminobutyric acid type A receptors (GABAARs) that are enriched at functionally diverse synapses via mechanisms that remain unclear. Using isothermal titration calorimetry and complementary methods we demonstrate an exclusive low micromolar binding of collybistin to the α2-subunit of GABAARs. To explore the biological relevance of collybistin-α2-subunit selectivity, we generate mice with a mutation in the α2-subunit-collybistin binding region (Gabra2-1). The mutation results in loss of a distinct subset of inhibitory synapses and decreased amplitude of inhibitory synaptic currents. Gabra2–1 mice have a striking phenotype characterized by increased susceptibility to seizures and early mortality. Surviving Gabra2-1 mice show anxiety and elevations in electroencephalogram δ power, which are ameliorated by treatment with the α2/α3-selective positive modulator, AZD7325. Taken together, our results demonstrate an α2-subunit selective binding of collybistin, which plays a key role in patterned brain activity, particularly during development.

@article{hines2018developmental, abstract = {Fast inhibitory synaptic transmission is mediated by γ-aminobutyric acid type A receptors (GABAARs) that are enriched at functionally diverse synapses via mechanisms that remain unclear. Using isothermal titration calorimetry and complementary methods we demonstrate an exclusive low micromolar binding of collybistin to the α2-subunit of GABAARs. To explore the biological relevance of collybistin-α2-subunit selectivity, we generate mice with a mutation in the α2-subunit-collybistin binding region (Gabra2-1). The mutation results in loss of a distinct subset of inhibitory synapses and decreased amplitude of inhibitory synaptic currents. Gabra2–1 mice have a striking phenotype characterized by increased susceptibility to seizures and early mortality. Surviving Gabra2-1 mice show anxiety and elevations in electroencephalogram δ power, which are ameliorated by treatment with the α2/α3-selective positive modulator, AZD7325. Taken together, our results demonstrate an α2-subunit selective binding of collybistin, which plays a key role in patterned brain activity, particularly during development.}, author = {Hines, Rochelle M. and Maric, Hans Michael and Hines, Dustin J. and Modgil, Amit and Panzanelli, Patrizia and Nakamura, Yasuko and Nathanson, Anna J. and Cross, Alan and Deeb, Tarek and Brandon, Nicholas J. and Davies, Paul and Fritschy, Jean-Marc and Schindelin, Hermann and Moss, Stephen J.}, journal = {Nature Communications}, keywords = {maric}, number = 1, pages = {3130–}, title = {Developmental seizures and mortality result from reducing GABAA receptor α2-subunit interaction with collybistin}, volume = 9, year = 2018 }

%0 Journal Article %1 hines2018developmental %A Hines, Rochelle M. %A Maric, Hans Michael %A Hines, Dustin J. %A Modgil, Amit %A Panzanelli, Patrizia %A Nakamura, Yasuko %A Nathanson, Anna J. %A Cross, Alan %A Deeb, Tarek %A Brandon, Nicholas J. %A Davies, Paul %A Fritschy, Jean-Marc %A Schindelin, Hermann %A Moss, Stephen J. %D 2018 %J Nature Communications %N 1 %P 3130-- %R 10.1038/s41467-018-05481-1 %T Developmental seizures and mortality result from reducing GABAA receptor α2-subunit interaction with collybistin %U https://doi.org/10.1038/s41467-018-05481-1 %V 9 %X Fast inhibitory synaptic transmission is mediated by γ-aminobutyric acid type A receptors (GABAARs) that are enriched at functionally diverse synapses via mechanisms that remain unclear. Using isothermal titration calorimetry and complementary methods we demonstrate an exclusive low micromolar binding of collybistin to the α2-subunit of GABAARs. To explore the biological relevance of collybistin-α2-subunit selectivity, we generate mice with a mutation in the α2-subunit-collybistin binding region (Gabra2-1). The mutation results in loss of a distinct subset of inhibitory synapses and decreased amplitude of inhibitory synaptic currents. Gabra2–1 mice have a striking phenotype characterized by increased susceptibility to seizures and early mortality. Surviving Gabra2-1 mice show anxiety and elevations in electroencephalogram δ power, which are ameliorated by treatment with the α2/α3-selective positive modulator, AZD7325. Taken together, our results demonstrate an α2-subunit selective binding of collybistin, which plays a key role in patterned brain activity, particularly during development.

2017[ to top ]

Association with Aurora-A Controls N-MYC-Dependent Promoter Escape and Pause Release of RNA Polymerase II during the Cell Cycle Büchel, Gabriele; Carstensen, Anne; Mak, Ka-Yan; Roeschert, Isabelle; Leen, Eoin; Sumara, Olga; Hofstetter, Julia; Herold, Steffi; Kalb, Jacqueline; Baluapuri, Apoorva; Poon, Evon; Kwok, Colin; Chesler, Louis; Maric, Hans Michael; Rickman, David S.; Wolf, Elmar; Bayliss, Richard; Walz, Susanne; Eilers, Martin in Cell Reports (2017). 21(12) 3483–3497.
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Summary MYC proteins bind globally to active promoters and promote transcriptional elongation by RNA polymerase II (Pol II). To identify effector proteins that mediate this function, we performed mass spectrometry on N-MYC complexes in neuroblastoma cells. The analysis shows that N-MYC forms complexes with TFIIIC, TOP2A, and RAD21, a subunit of cohesin. N-MYC and TFIIIC bind to overlapping sites in thousands of Pol II promoters and intergenic regions. TFIIIC promotes association of RAD21 with N-MYC target sites and is required for N-MYC-dependent promoter escape and pause release of Pol II. Aurora-A competes with binding of TFIIIC and RAD21 to N-MYC in vitro and antagonizes association of TOP2A, TFIIIC, and RAD21 with N-MYC during S phase, blocking N-MYC-dependent release of Pol II from the promoter. Inhibition of Aurora-A in S phase restores RAD21 and TFIIIC binding to chromatin and partially restores N-MYC-dependent transcriptional elongation. We propose that complex formation with Aurora-A controls N-MYC function during the cell cycle.

@article{buchel2017association, abstract = {Summary MYC proteins bind globally to active promoters and promote transcriptional elongation by RNA polymerase II (Pol II). To identify effector proteins that mediate this function, we performed mass spectrometry on N-MYC complexes in neuroblastoma cells. The analysis shows that N-MYC forms complexes with TFIIIC, TOP2A, and RAD21, a subunit of cohesin. N-MYC and TFIIIC bind to overlapping sites in thousands of Pol II promoters and intergenic regions. TFIIIC promotes association of RAD21 with N-MYC target sites and is required for N-MYC-dependent promoter escape and pause release of Pol II. Aurora-A competes with binding of TFIIIC and RAD21 to N-MYC in vitro and antagonizes association of TOP2A, TFIIIC, and RAD21 with N-MYC during S phase, blocking N-MYC-dependent release of Pol II from the promoter. Inhibition of Aurora-A in S phase restores RAD21 and TFIIIC binding to chromatin and partially restores N-MYC-dependent transcriptional elongation. We propose that complex formation with Aurora-A controls N-MYC function during the cell cycle.}, author = {Büchel, Gabriele and Carstensen, Anne and Mak, Ka-Yan and Roeschert, Isabelle and Leen, Eoin and Sumara, Olga and Hofstetter, Julia and Herold, Steffi and Kalb, Jacqueline and Baluapuri, Apoorva and Poon, Evon and Kwok, Colin and Chesler, Louis and Maric, Hans Michael and Rickman, David S. and Wolf, Elmar and Bayliss, Richard and Walz, Susanne and Eilers, Martin}, journal = {Cell Reports}, keywords = {maric}, number = 12, pages = {3483–3497}, title = {Association with Aurora-A Controls N-MYC-Dependent Promoter Escape and Pause Release of RNA Polymerase II during the Cell Cycle}, volume = 21, year = 2017 }

%0 Journal Article %1 buchel2017association %A Büchel, Gabriele %A Carstensen, Anne %A Mak, Ka-Yan %A Roeschert, Isabelle %A Leen, Eoin %A Sumara, Olga %A Hofstetter, Julia %A Herold, Steffi %A Kalb, Jacqueline %A Baluapuri, Apoorva %A Poon, Evon %A Kwok, Colin %A Chesler, Louis %A Maric, Hans Michael %A Rickman, David S. %A Wolf, Elmar %A Bayliss, Richard %A Walz, Susanne %A Eilers, Martin %D 2017 %J Cell Reports %N 12 %P 3483--3497 %R https://doi.org/10.1016/j.celrep.2017.11.090 %T Association with Aurora-A Controls N-MYC-Dependent Promoter Escape and Pause Release of RNA Polymerase II during the Cell Cycle %U http://www.sciencedirect.com/science/article/pii/S2211124717317576 %V 21 %X Summary MYC proteins bind globally to active promoters and promote transcriptional elongation by RNA polymerase II (Pol II). To identify effector proteins that mediate this function, we performed mass spectrometry on N-MYC complexes in neuroblastoma cells. The analysis shows that N-MYC forms complexes with TFIIIC, TOP2A, and RAD21, a subunit of cohesin. N-MYC and TFIIIC bind to overlapping sites in thousands of Pol II promoters and intergenic regions. TFIIIC promotes association of RAD21 with N-MYC target sites and is required for N-MYC-dependent promoter escape and pause release of Pol II. Aurora-A competes with binding of TFIIIC and RAD21 to N-MYC in vitro and antagonizes association of TOP2A, TFIIIC, and RAD21 with N-MYC during S phase, blocking N-MYC-dependent release of Pol II from the promoter. Inhibition of Aurora-A in S phase restores RAD21 and TFIIIC binding to chromatin and partially restores N-MYC-dependent transcriptional elongation. We propose that complex formation with Aurora-A controls N-MYC function during the cell cycle.
Incorporation studies of clickable ceramides in Jurkat cell plasma membranes Walter, T.; Schlegel, J.; Burgert, A.; Kurz, A.; Seibel, J.; Sauer, M. in Chem. Commun. (2017). 53(51) 6836–6839.
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The incorporation properties of ceramide analogues for click chemistry in Jurkat T cells were investigated. The analogues varied in the acyl chain length and the position of the functional group for click chemistry. Fluorescence microscopy studies including anisotropy and quenching experiments showed significant differences in the accessibility of the functional group indicating different incorporation properties into the plasma membrane.

@article{walter2017incorporation, abstract = {The incorporation properties of ceramide analogues for click chemistry in Jurkat T cells were investigated. The analogues varied in the acyl chain length and the position of the functional group for click chemistry. Fluorescence microscopy studies including anisotropy and quenching experiments showed significant differences in the accessibility of the functional group indicating different incorporation properties into the plasma membrane.}, author = {Walter, T. and Schlegel, J. and Burgert, A. and Kurz, A. and Seibel, J. and Sauer, M.}, journal = {Chem. Commun.}, keywords = {sauer}, number = 51, pages = {6836–6839}, publisher = {The Royal Society of Chemistry}, title = {Incorporation studies of clickable ceramides in Jurkat cell plasma membranes}, volume = 53, year = 2017 }

%0 Journal Article %1 walter2017incorporation %A Walter, T. %A Schlegel, J. %A Burgert, A. %A Kurz, A. %A Seibel, J. %A Sauer, M. %D 2017 %I The Royal Society of Chemistry %J Chem. Commun. %N 51 %P 6836--6839 %R 10.1039/C7CC01220A %T Incorporation studies of clickable ceramides in Jurkat cell plasma membranes %U http://dx.doi.org/10.1039/C7CC01220A %V 53 %X The incorporation properties of ceramide analogues for click chemistry in Jurkat T cells were investigated. The analogues varied in the acyl chain length and the position of the functional group for click chemistry. Fluorescence microscopy studies including anisotropy and quenching experiments showed significant differences in the accessibility of the functional group indicating different incorporation properties into the plasma membrane.
Parallel experimental design and multivariate analysis provides efficient screening of cell culture media supplements to improve biosimilar product quality Brühlmann, David; Sokolov, Michael; Butté, Alessandro; Sauer, Markus; Hemberger, Jürgen; Souquet, Jonathan; Broly, Hervé; Jordan, Martin in Biotechnology and Bioengineering (2017). 114(7) 1448–1458.
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Rational and high-throughput optimization of mammalian cell culture media has a great potential to modulate recombinant protein product quality. We present a process design method based on parallel design-of-experiment (DoE) of CHO fed-batch cultures in 96-deepwell plates to modulate monoclonal antibody (mAb) glycosylation using medium supplements. To reduce the risk of losing valuable information in an intricate joint screening, 17 compounds were separated into five different groups, considering their mode of biological action. The concentration ranges of the medium supplements were defined according to information encountered in the literature and in-house experience. The screening experiments produced wide glycosylation pattern ranges. Multivariate analysis including principal component analysis and decision trees was used to select the best performing glycosylation modulators. Subsequent D-optimal quadratic design with four factors (three promising compounds and temperature shift) in shake tubes confirmed the outcome of the selection process and provided a solid basis for sequential process development at a larger scale. The glycosylation profile with respect to the specifications for biosimilarity was greatly improved in shake tube experiments: 75% of the conditions were equally close or closer to the specifications for biosimilarity than the best 25% in 96-deepwell plates. Biotechnol. Bioeng. 2017;114: 1448–1458. © 2017 Wiley Periodicals, Inc.

@article{bruhlmann2017parallel, abstract = {Rational and high-throughput optimization of mammalian cell culture media has a great potential to modulate recombinant protein product quality. We present a process design method based on parallel design-of-experiment (DoE) of CHO fed-batch cultures in 96-deepwell plates to modulate monoclonal antibody (mAb) glycosylation using medium supplements. To reduce the risk of losing valuable information in an intricate joint screening, 17 compounds were separated into five different groups, considering their mode of biological action. The concentration ranges of the medium supplements were defined according to information encountered in the literature and in-house experience. The screening experiments produced wide glycosylation pattern ranges. Multivariate analysis including principal component analysis and decision trees was used to select the best performing glycosylation modulators. Subsequent D-optimal quadratic design with four factors (three promising compounds and temperature shift) in shake tubes confirmed the outcome of the selection process and provided a solid basis for sequential process development at a larger scale. The glycosylation profile with respect to the specifications for biosimilarity was greatly improved in shake tube experiments: 75% of the conditions were equally close or closer to the specifications for biosimilarity than the best 25% in 96-deepwell plates. Biotechnol. Bioeng. 2017;114: 1448–1458. © 2017 Wiley Periodicals, Inc.}, author = {Brühlmann, David and Sokolov, Michael and Butté, Alessandro and Sauer, Markus and Hemberger, Jürgen and Souquet, Jonathan and Broly, Hervé and Jordan, Martin}, journal = {Biotechnology and Bioengineering}, keywords = {sauer}, number = 7, pages = {1448–1458}, title = {Parallel experimental design and multivariate analysis provides efficient screening of cell culture media supplements to improve biosimilar product quality}, volume = 114, year = 2017 }

%0 Journal Article %1 bruhlmann2017parallel %A Brühlmann, David %A Sokolov, Michael %A Butté, Alessandro %A Sauer, Markus %A Hemberger, Jürgen %A Souquet, Jonathan %A Broly, Hervé %A Jordan, Martin %D 2017 %J Biotechnology and Bioengineering %N 7 %P 1448--1458 %R 10.1002/bit.26269 %T Parallel experimental design and multivariate analysis provides efficient screening of cell culture media supplements to improve biosimilar product quality %U http://dx.doi.org/10.1002/bit.26269 %V 114 %X Rational and high-throughput optimization of mammalian cell culture media has a great potential to modulate recombinant protein product quality. We present a process design method based on parallel design-of-experiment (DoE) of CHO fed-batch cultures in 96-deepwell plates to modulate monoclonal antibody (mAb) glycosylation using medium supplements. To reduce the risk of losing valuable information in an intricate joint screening, 17 compounds were separated into five different groups, considering their mode of biological action. The concentration ranges of the medium supplements were defined according to information encountered in the literature and in-house experience. The screening experiments produced wide glycosylation pattern ranges. Multivariate analysis including principal component analysis and decision trees was used to select the best performing glycosylation modulators. Subsequent D-optimal quadratic design with four factors (three promising compounds and temperature shift) in shake tubes confirmed the outcome of the selection process and provided a solid basis for sequential process development at a larger scale. The glycosylation profile with respect to the specifications for biosimilarity was greatly improved in shake tube experiments: 75% of the conditions were equally close or closer to the specifications for biosimilarity than the best 25% in 96-deepwell plates. Biotechnol. Bioeng. 2017;114: 1448–1458. © 2017 Wiley Periodicals, Inc.
Cadherin-13 Deficiency Increases Dorsal Raphe 5-HT Neuron Density and Prefrontal Cortex Innervation in the Mouse Brain Forero, Andrea; Rivero, Olga; Wäldchen, Sina; Ku, Hsing-Ping; Kiser, Dominik P.; Gärtner, Yvonne; Pennington, Laura S.; Waider, Jonas; Gaspar, Patricia; Jansch, Charline; Edenhofer, Frank; Resink, Thérèse J.; Blum, Robert; Sauer, Markus; Lesch, Klaus-Peter in Frontiers in Cellular Neuroscience (2017). 11 307-.
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Background: During early prenatal stages of brain development, serotonin (5-HT)-specific neurons migrate through somal translocation to form the raphe nuclei and subsequently begin to project to their target regions. The rostral cluster of cells, comprising the median and dorsal raphe (DR), innervates anterior regions of the brain, including the prefrontal cortex. Differential analysis of the mouse 5-HT system transcriptome identified enrichment of cell adhesion molecules in 5-HT neurons of the DR. One of these molecules, cadherin-13 (Cdh13) has been shown to play a role in cell migration, axon pathfinding and synaptogenesis. This study aimed to investigate the contribution of Cdh13 to the development of the murine brain 5-HT system. Methods: For detection of Cdh13 and components of the 5-HT system at different embryonic developmental stages of the mouse brain, we employed immunofluorescence protocols and imaging techniques, including epifluorescence, confocal and structured illumination microscopy. The consequence of CDH13 loss-of-function mutations on brain 5-HT system development was explored in a mouse model of Cdh13 deficiency. Results: Our data show that in murine embryonic brain Cdh13 is strongly expressed on 5-HT specific neurons of the DR and in radial glial cells (RGCs), which are critically involved in regulation of neuronal migration. We observed that 5-HT neurons are intertwined with these RGCs, suggesting that these neurons undergo RGC-guided migration. Cdh13 is present at points of intersection between these two cell types. Compared to wildtype controls, Cdh13-deficient mouse embryos display increased cell densities in the DR at E13.5, E17.5 and adulthood, and higher serotonergic innervation of the prefrontal cortex at E17.5. Conclusion: Our findings provide evidence for a role of CDH13 in the development of the serotonergic system in early embryonic stages. Specifically, we indicate that CDH13 deficiency affects the cell density of the developing DR and the posterior innervation of the PFC, and therefore might be involved in the migration, axonal outgrowth and terminal target finding of DR 5-HT neurons. Dysregulation of CDH13 expression may thus contribute to alterations in this system of neurotransmission, impacting cognitive function, which is frequently impaired in neurodevelopmental disorders including attention-deficit/hyperactivity and autism spectrum disorders.

@article{forero2017cadherin13, abstract = {Background: During early prenatal stages of brain development, serotonin (5-HT)-specific neurons migrate through somal translocation to form the raphe nuclei and subsequently begin to project to their target regions. The rostral cluster of cells, comprising the median and dorsal raphe (DR), innervates anterior regions of the brain, including the prefrontal cortex. Differential analysis of the mouse 5-HT system transcriptome identified enrichment of cell adhesion molecules in 5-HT neurons of the DR. One of these molecules, cadherin-13 (Cdh13) has been shown to play a role in cell migration, axon pathfinding and synaptogenesis. This study aimed to investigate the contribution of Cdh13 to the development of the murine brain 5-HT system. Methods: For detection of Cdh13 and components of the 5-HT system at different embryonic developmental stages of the mouse brain, we employed immunofluorescence protocols and imaging techniques, including epifluorescence, confocal and structured illumination microscopy. The consequence of CDH13 loss-of-function mutations on brain 5-HT system development was explored in a mouse model of Cdh13 deficiency. Results: Our data show that in murine embryonic brain Cdh13 is strongly expressed on 5-HT specific neurons of the DR and in radial glial cells (RGCs), which are critically involved in regulation of neuronal migration. We observed that 5-HT neurons are intertwined with these RGCs, suggesting that these neurons undergo RGC-guided migration. Cdh13 is present at points of intersection between these two cell types. Compared to wildtype controls, Cdh13-deficient mouse embryos display increased cell densities in the DR at E13.5, E17.5 and adulthood, and higher serotonergic innervation of the prefrontal cortex at E17.5. Conclusion: Our findings provide evidence for a role of CDH13 in the development of the serotonergic system in early embryonic stages. Specifically, we indicate that CDH13 deficiency affects the cell density of the developing DR and the posterior innervation of the PFC, and therefore might be involved in the migration, axonal outgrowth and terminal target finding of DR 5-HT neurons. Dysregulation of CDH13 expression may thus contribute to alterations in this system of neurotransmission, impacting cognitive function, which is frequently impaired in neurodevelopmental disorders including attention-deficit/hyperactivity and autism spectrum disorders.}, author = {Forero, Andrea and Rivero, Olga and Wäldchen, Sina and Ku, Hsing-Ping and Kiser, Dominik P. and Gärtner, Yvonne and Pennington, Laura S. and Waider, Jonas and Gaspar, Patricia and Jansch, Charline and Edenhofer, Frank and Resink, Thérèse J. and Blum, Robert and Sauer, Markus and Lesch, Klaus-Peter}, journal = {Frontiers in Cellular Neuroscience}, keywords = {sauer}, pages = {307–}, title = {Cadherin-13 Deficiency Increases Dorsal Raphe 5-HT Neuron Density and Prefrontal Cortex Innervation in the Mouse Brain}, volume = 11, year = 2017 }

%0 Journal Article %1 forero2017cadherin13 %A Forero, Andrea %A Rivero, Olga %A Wäldchen, Sina %A Ku, Hsing-Ping %A Kiser, Dominik P. %A Gärtner, Yvonne %A Pennington, Laura S. %A Waider, Jonas %A Gaspar, Patricia %A Jansch, Charline %A Edenhofer, Frank %A Resink, Thérèse J. %A Blum, Robert %A Sauer, Markus %A Lesch, Klaus-Peter %D 2017 %J Frontiers in Cellular Neuroscience %P 307-- %T Cadherin-13 Deficiency Increases Dorsal Raphe 5-HT Neuron Density and Prefrontal Cortex Innervation in the Mouse Brain %U https://www.frontiersin.org/article/10.3389/fncel.2017.00307 %V 11 %X Background: During early prenatal stages of brain development, serotonin (5-HT)-specific neurons migrate through somal translocation to form the raphe nuclei and subsequently begin to project to their target regions. The rostral cluster of cells, comprising the median and dorsal raphe (DR), innervates anterior regions of the brain, including the prefrontal cortex. Differential analysis of the mouse 5-HT system transcriptome identified enrichment of cell adhesion molecules in 5-HT neurons of the DR. One of these molecules, cadherin-13 (Cdh13) has been shown to play a role in cell migration, axon pathfinding and synaptogenesis. This study aimed to investigate the contribution of Cdh13 to the development of the murine brain 5-HT system. Methods: For detection of Cdh13 and components of the 5-HT system at different embryonic developmental stages of the mouse brain, we employed immunofluorescence protocols and imaging techniques, including epifluorescence, confocal and structured illumination microscopy. The consequence of CDH13 loss-of-function mutations on brain 5-HT system development was explored in a mouse model of Cdh13 deficiency. Results: Our data show that in murine embryonic brain Cdh13 is strongly expressed on 5-HT specific neurons of the DR and in radial glial cells (RGCs), which are critically involved in regulation of neuronal migration. We observed that 5-HT neurons are intertwined with these RGCs, suggesting that these neurons undergo RGC-guided migration. Cdh13 is present at points of intersection between these two cell types. Compared to wildtype controls, Cdh13-deficient mouse embryos display increased cell densities in the DR at E13.5, E17.5 and adulthood, and higher serotonergic innervation of the prefrontal cortex at E17.5. Conclusion: Our findings provide evidence for a role of CDH13 in the development of the serotonergic system in early embryonic stages. Specifically, we indicate that CDH13 deficiency affects the cell density of the developing DR and the posterior innervation of the PFC, and therefore might be involved in the migration, axonal outgrowth and terminal target finding of DR 5-HT neurons. Dysregulation of CDH13 expression may thus contribute to alterations in this system of neurotransmission, impacting cognitive function, which is frequently impaired in neurodevelopmental disorders including attention-deficit/hyperactivity and autism spectrum disorders.
Mechano-dependent signaling by Latrophilin/CIRL quenches cAMP in proprioceptive neurons Scholz, Nicole; Guan, Chonglin; Nieberler, Matthias; Grotemeyer, Alexander; Maiellaro, Isabella; Gao, Shiqiang; Beck, Sebastian; Pawlak, Matthias; Sauer, Markus; Asan, Esther; Rothemund, Sven; Winkler, Jana; Prömel, Simone; Nagel, Georg; Langenhan, Tobias; Kittel, Robert J in eLife, (H. J. Bellen, Hrsg.) (2017). 6 e28360-.
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Adhesion-type G protein-coupled receptors (aGPCRs), a large molecule family with over 30 members in humans, operate in organ development, brain function and govern immunological responses. Correspondingly, this receptor family is linked to a multitude of diverse human diseases. aGPCRs have been suggested to possess mechanosensory properties, though their mechanism of action is fully unknown. Here we show that the Drosophila aGPCR Latrophilin/dCIRL acts in mechanosensory neurons by modulating ionotropic receptor currents, the initiating step of cellular mechanosensation. This process depends on the length of the extended ectodomain and the tethered agonist of the receptor, but not on its autoproteolysis, a characteristic biochemical feature of the aGPCR family. Intracellularly, dCIRL quenches cAMP levels upon mechanical activation thereby specifically increasing the mechanosensitivity of neurons. These results provide direct evidence that the aGPCR dCIRL acts as a molecular sensor and signal transducer that detects and converts mechanical stimuli into a metabotropic response.

@article{scholz2017mechanodependent, abstract = {Adhesion-type G protein-coupled receptors (aGPCRs), a large molecule family with over 30 members in humans, operate in organ development, brain function and govern immunological responses. Correspondingly, this receptor family is linked to a multitude of diverse human diseases. aGPCRs have been suggested to possess mechanosensory properties, though their mechanism of action is fully unknown. Here we show that the Drosophila aGPCR Latrophilin/dCIRL acts in mechanosensory neurons by modulating ionotropic receptor currents, the initiating step of cellular mechanosensation. This process depends on the length of the extended ectodomain and the tethered agonist of the receptor, but not on its autoproteolysis, a characteristic biochemical feature of the aGPCR family. Intracellularly, dCIRL quenches cAMP levels upon mechanical activation thereby specifically increasing the mechanosensitivity of neurons. These results provide direct evidence that the aGPCR dCIRL acts as a molecular sensor and signal transducer that detects and converts mechanical stimuli into a metabotropic response.}, author = {Scholz, Nicole and Guan, Chonglin and Nieberler, Matthias and Grotemeyer, Alexander and Maiellaro, Isabella and Gao, Shiqiang and Beck, Sebastian and Pawlak, Matthias and Sauer, Markus and Asan, Esther and Rothemund, Sven and Winkler, Jana and Prömel, Simone and Nagel, Georg and Langenhan, Tobias and Kittel, Robert J}, editor = {Bellen, Hugo J}, journal = {eLife}, keywords = {sauer}, pages = {e28360–}, publisher = {eLife Sciences Publications, Ltd}, title = {Mechano-dependent signaling by Latrophilin/CIRL quenches cAMP in proprioceptive neurons}, volume = 6, year = 2017 }

%0 Journal Article %1 scholz2017mechanodependent %A Scholz, Nicole %A Guan, Chonglin %A Nieberler, Matthias %A Grotemeyer, Alexander %A Maiellaro, Isabella %A Gao, Shiqiang %A Beck, Sebastian %A Pawlak, Matthias %A Sauer, Markus %A Asan, Esther %A Rothemund, Sven %A Winkler, Jana %A Prömel, Simone %A Nagel, Georg %A Langenhan, Tobias %A Kittel, Robert J %D 2017 %E Bellen, Hugo J %I eLife Sciences Publications, Ltd %J eLife %P e28360-- %R 10.7554/eLife.28360 %T Mechano-dependent signaling by Latrophilin/CIRL quenches cAMP in proprioceptive neurons %U https://doi.org/10.7554/eLife.28360 %V 6 %X Adhesion-type G protein-coupled receptors (aGPCRs), a large molecule family with over 30 members in humans, operate in organ development, brain function and govern immunological responses. Correspondingly, this receptor family is linked to a multitude of diverse human diseases. aGPCRs have been suggested to possess mechanosensory properties, though their mechanism of action is fully unknown. Here we show that the Drosophila aGPCR Latrophilin/dCIRL acts in mechanosensory neurons by modulating ionotropic receptor currents, the initiating step of cellular mechanosensation. This process depends on the length of the extended ectodomain and the tethered agonist of the receptor, but not on its autoproteolysis, a characteristic biochemical feature of the aGPCR family. Intracellularly, dCIRL quenches cAMP levels upon mechanical activation thereby specifically increasing the mechanosensitivity of neurons. These results provide direct evidence that the aGPCR dCIRL acts as a molecular sensor and signal transducer that detects and converts mechanical stimuli into a metabotropic response.
Cyanine Conformational Restraint in the Far-Red Range Michie, Megan S.; Götz, Ralph; Franke, Christian; Bowler, Matthew; Kumari, Nikita; Magidson, Valentin; Levitus, Marcia; Loncarek, Jadranka; Sauer, Markus; Schnermann, Martin J. in J. Am. Chem. Soc. (2017). 139(36) 12406–12409.
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Far-red cyanine fluorophores find extensive use in modern microscopy despite modest quantum yields. To improve the photon output of these molecules, we report a synthetic strategy that blocks the major deactivation pathway: excited-state trans-to-cis polyene rotation. In the key transformation, a protected dialdehyde precursor undergoes a cascade reaction to install the requisite tetracyclic ring system. The resulting molecules exhibit the characteristic features of conformational restraint, including improved fluorescence quantum yield and extended lifetime. Moreover, these compounds recover from hydride reduction with dramatically improved efficiency. These observations enable efficient single-molecule localization microscopy in oxygenated buffer without addition of thiols. Enabled by modern organic synthesis, these studies provide a new class of far-red dyes with promising spectroscopic and chemical properties.

@article{michie2017cyanine, abstract = {Far-red cyanine fluorophores find extensive use in modern microscopy despite modest quantum yields. To improve the photon output of these molecules, we report a synthetic strategy that blocks the major deactivation pathway: excited-state trans-to-cis polyene rotation. In the key transformation, a protected dialdehyde precursor undergoes a cascade reaction to install the requisite tetracyclic ring system. The resulting molecules exhibit the characteristic features of conformational restraint, including improved fluorescence quantum yield and extended lifetime. Moreover, these compounds recover from hydride reduction with dramatically improved efficiency. These observations enable efficient single-molecule localization microscopy in oxygenated buffer without addition of thiols. Enabled by modern organic synthesis, these studies provide a new class of far-red dyes with promising spectroscopic and chemical properties.}, author = {Michie, Megan S. and Götz, Ralph and Franke, Christian and Bowler, Matthew and Kumari, Nikita and Magidson, Valentin and Levitus, Marcia and Loncarek, Jadranka and Sauer, Markus and Schnermann, Martin J.}, booktitle = {Journal of the American Chemical Society}, journal = {J. Am. Chem. Soc.}, keywords = {sauer}, month = {sep}, number = 36, pages = {12406–12409}, publisher = {American Chemical Society}, title = {Cyanine Conformational Restraint in the Far-Red Range}, volume = 139, year = 2017 }

%0 Journal Article %1 michie2017cyanine %A Michie, Megan S. %A Götz, Ralph %A Franke, Christian %A Bowler, Matthew %A Kumari, Nikita %A Magidson, Valentin %A Levitus, Marcia %A Loncarek, Jadranka %A Sauer, Markus %A Schnermann, Martin J. %B Journal of the American Chemical Society %D 2017 %I American Chemical Society %J J. Am. Chem. Soc. %N 36 %P 12406--12409 %R 10.1021/jacs.7b07272 %T Cyanine Conformational Restraint in the Far-Red Range %U http://dx.doi.org/10.1021/jacs.7b07272 %V 139 %X Far-red cyanine fluorophores find extensive use in modern microscopy despite modest quantum yields. To improve the photon output of these molecules, we report a synthetic strategy that blocks the major deactivation pathway: excited-state trans-to-cis polyene rotation. In the key transformation, a protected dialdehyde precursor undergoes a cascade reaction to install the requisite tetracyclic ring system. The resulting molecules exhibit the characteristic features of conformational restraint, including improved fluorescence quantum yield and extended lifetime. Moreover, these compounds recover from hydride reduction with dramatically improved efficiency. These observations enable efficient single-molecule localization microscopy in oxygenated buffer without addition of thiols. Enabled by modern organic synthesis, these studies provide a new class of far-red dyes with promising spectroscopic and chemical properties.
CD56 Is a Pathogen Recognition Receptor on Human Natural Killer Cells Ziegler, Sabrina; Weiss, Esther; Schmitt, Anna-Lena; Schlegel, Jan; Burgert, Anne; Terpitz, Ulrich; Sauer, Markus; Moretta, Lorenzo; Sivori, Simona; Leonhardt, Ines; Kurzai, Oliver; Einsele, Hermann; Loeffler, Juergen in Scientific Reports (2017). 7(1) 6138-.
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Aspergillus (A.) fumigatus is an opportunistic fungal mold inducing invasive aspergillosis (IA) in immunocompromised patients. Although antifungal activity of human natural killer (NK) cells was shown in previous studies, the underlying cellular mechanisms and pathogen recognition receptors (PRRs) are still unknown. Using flow cytometry we were able to show that the fluorescence positivity of the surface receptor CD56 significantly decreased upon fungal contact. To visualize the interaction site of NK cells and A. fumigatus we used SEM, CLSM and dSTORM techniques, which clearly demonstrated that NK cells directly interact with A. fumigatus via CD56 and that CD56 is re-organized and accumulated at this interaction site time-dependently. The inhibition of the cytoskeleton showed that the receptor re-organization was an active process dependent on actin re-arrangements. Furthermore, we could show that CD56 plays a role in the fungus mediated NK cell activation, since blocking of CD56 surface receptor reduced fungal mediated NK cell activation and reduced cytokine secretion. These results confirmed the direct interaction of NK cells and A. fumigatus, leading to the conclusion that CD56 is a pathogen recognition receptor. These findings give new insights into the functional role of CD56 in the pathogen recognition during the innate immune response.

@article{ziegler2017pathogen, abstract = {Aspergillus (A.) fumigatus is an opportunistic fungal mold inducing invasive aspergillosis (IA) in immunocompromised patients. Although antifungal activity of human natural killer (NK) cells was shown in previous studies, the underlying cellular mechanisms and pathogen recognition receptors (PRRs) are still unknown. Using flow cytometry we were able to show that the fluorescence positivity of the surface receptor CD56 significantly decreased upon fungal contact. To visualize the interaction site of NK cells and A. fumigatus we used SEM, CLSM and dSTORM techniques, which clearly demonstrated that NK cells directly interact with A. fumigatus via CD56 and that CD56 is re-organized and accumulated at this interaction site time-dependently. The inhibition of the cytoskeleton showed that the receptor re-organization was an active process dependent on actin re-arrangements. Furthermore, we could show that CD56 plays a role in the fungus mediated NK cell activation, since blocking of CD56 surface receptor reduced fungal mediated NK cell activation and reduced cytokine secretion. These results confirmed the direct interaction of NK cells and A. fumigatus, leading to the conclusion that CD56 is a pathogen recognition receptor. These findings give new insights into the functional role of CD56 in the pathogen recognition during the innate immune response.}, author = {Ziegler, Sabrina and Weiss, Esther and Schmitt, Anna-Lena and Schlegel, Jan and Burgert, Anne and Terpitz, Ulrich and Sauer, Markus and Moretta, Lorenzo and Sivori, Simona and Leonhardt, Ines and Kurzai, Oliver and Einsele, Hermann and Loeffler, Juergen}, journal = {Scientific Reports}, keywords = {terpitz}, number = 1, pages = {6138–}, title = {CD56 Is a Pathogen Recognition Receptor on Human Natural Killer Cells}, volume = 7, year = 2017 }

%0 Journal Article %1 ziegler2017pathogen %A Ziegler, Sabrina %A Weiss, Esther %A Schmitt, Anna-Lena %A Schlegel, Jan %A Burgert, Anne %A Terpitz, Ulrich %A Sauer, Markus %A Moretta, Lorenzo %A Sivori, Simona %A Leonhardt, Ines %A Kurzai, Oliver %A Einsele, Hermann %A Loeffler, Juergen %D 2017 %J Scientific Reports %N 1 %P 6138-- %R 10.1038/s41598-017-06238-4 %T CD56 Is a Pathogen Recognition Receptor on Human Natural Killer Cells %U https://doi.org/10.1038/s41598-017-06238-4 %V 7 %X Aspergillus (A.) fumigatus is an opportunistic fungal mold inducing invasive aspergillosis (IA) in immunocompromised patients. Although antifungal activity of human natural killer (NK) cells was shown in previous studies, the underlying cellular mechanisms and pathogen recognition receptors (PRRs) are still unknown. Using flow cytometry we were able to show that the fluorescence positivity of the surface receptor CD56 significantly decreased upon fungal contact. To visualize the interaction site of NK cells and A. fumigatus we used SEM, CLSM and dSTORM techniques, which clearly demonstrated that NK cells directly interact with A. fumigatus via CD56 and that CD56 is re-organized and accumulated at this interaction site time-dependently. The inhibition of the cytoskeleton showed that the receptor re-organization was an active process dependent on actin re-arrangements. Furthermore, we could show that CD56 plays a role in the fungus mediated NK cell activation, since blocking of CD56 surface receptor reduced fungal mediated NK cell activation and reduced cytokine secretion. These results confirmed the direct interaction of NK cells and A. fumigatus, leading to the conclusion that CD56 is a pathogen recognition receptor. These findings give new insights into the functional role of CD56 in the pathogen recognition during the innate immune response.
Quantifying protein densities on cell membranes using super-resolution optical fluctuation imaging Lukeš, Tomáš; Glatzová, Daniela; Kvíčalová, Zuzana; Levet, Florian; Benda, Aleš; Letschert, Sebastian; Sauer, Markus; Brdička, Tomáš; Lasser, Theo; Cebecauer, Marek in Nature Communications (2017). 8(1) 1731-.
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Quantitative approaches for characterizing molecular organization of cell membrane molecules under physiological and pathological conditions profit from recently developed super-resolution imaging techniques. Current tools employ statistical algorithms to determine clusters of molecules based on single-molecule localization microscopy (SMLM) data. These approaches are limited by the ability of SMLM techniques to identify and localize molecules in densely populated areas and experimental conditions of sample preparation and image acquisition. We have developed a robust, model-free, quantitative clustering analysis to determine the distribution of membrane molecules that excels in densely labeled areas and is tolerant to various experimental conditions, i.e. multiple-blinking or high blinking rates. The method is based on a TIRF microscope followed by a super-resolution optical fluctuation imaging (SOFI) analysis. The effectiveness and robustness of the method is validated using simulated and experimental data investigating nanoscale distribution of CD4 glycoprotein mutants in the plasma membrane of T cells.

@article{lukes2017quantifying, abstract = {Quantitative approaches for characterizing molecular organization of cell membrane molecules under physiological and pathological conditions profit from recently developed super-resolution imaging techniques. Current tools employ statistical algorithms to determine clusters of molecules based on single-molecule localization microscopy (SMLM) data. These approaches are limited by the ability of SMLM techniques to identify and localize molecules in densely populated areas and experimental conditions of sample preparation and image acquisition. We have developed a robust, model-free, quantitative clustering analysis to determine the distribution of membrane molecules that excels in densely labeled areas and is tolerant to various experimental conditions, i.e. multiple-blinking or high blinking rates. The method is based on a TIRF microscope followed by a super-resolution optical fluctuation imaging (SOFI) analysis. The effectiveness and robustness of the method is validated using simulated and experimental data investigating nanoscale distribution of CD4 glycoprotein mutants in the plasma membrane of T cells.}, author = {Lukeš, Tomáš and Glatzová, Daniela and Kvíčalová, Zuzana and Levet, Florian and Benda, Aleš and Letschert, Sebastian and Sauer, Markus and Brdička, Tomáš and Lasser, Theo and Cebecauer, Marek}, journal = {Nature Communications}, keywords = {sauer}, number = 1, pages = {1731–}, title = {Quantifying protein densities on cell membranes using super-resolution optical fluctuation imaging}, volume = 8, year = 2017 }

%0 Journal Article %1 lukes2017quantifying %A Lukeš, Tomáš %A Glatzová, Daniela %A Kvíčalová, Zuzana %A Levet, Florian %A Benda, Aleš %A Letschert, Sebastian %A Sauer, Markus %A Brdička, Tomáš %A Lasser, Theo %A Cebecauer, Marek %D 2017 %J Nature Communications %N 1 %P 1731-- %R 10.1038/s41467-017-01857-x %T Quantifying protein densities on cell membranes using super-resolution optical fluctuation imaging %U https://doi.org/10.1038/s41467-017-01857-x %V 8 %X Quantitative approaches for characterizing molecular organization of cell membrane molecules under physiological and pathological conditions profit from recently developed super-resolution imaging techniques. Current tools employ statistical algorithms to determine clusters of molecules based on single-molecule localization microscopy (SMLM) data. These approaches are limited by the ability of SMLM techniques to identify and localize molecules in densely populated areas and experimental conditions of sample preparation and image acquisition. We have developed a robust, model-free, quantitative clustering analysis to determine the distribution of membrane molecules that excels in densely labeled areas and is tolerant to various experimental conditions, i.e. multiple-blinking or high blinking rates. The method is based on a TIRF microscope followed by a super-resolution optical fluctuation imaging (SOFI) analysis. The effectiveness and robustness of the method is validated using simulated and experimental data investigating nanoscale distribution of CD4 glycoprotein mutants in the plasma membrane of T cells.
Single-Molecule Localization Microscopy in Eukaryotes Sauer, Markus; Heilemann, Mike in Chem. Rev. (2017).
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Super-resolution fluorescence imaging by photoactivation or photoswitching of single fluorophores and position determination (single-molecule localization microscopy, SMLM) provides microscopic images with subdiffraction spatial resolution. This technology has enabled new insights into how proteins are organized in a cellular context, with a spatial resolution approaching virtually the molecular level. A unique strength of SMLM is that it delivers molecule-resolved information, along with super-resolved images of cellular structures. This allows quantitative access to cellular structures, for example, how proteins are distributed and organized and how they interact with other biomolecules. Ultimately, it is even possible to determine protein numbers in cells and the number of subunits in a protein complex. SMLM thus has the potential to pave the way toward a better understanding of how cells function at the molecular level. In this review, we describe how SMLM has contributed new knowledge in eukaryotic biology, and we specifically focus on quantitative biological data extracted from SMLM images.

@article{sauer2017singlemolecule, abstract = {Super-resolution fluorescence imaging by photoactivation or photoswitching of single fluorophores and position determination (single-molecule localization microscopy, SMLM) provides microscopic images with subdiffraction spatial resolution. This technology has enabled new insights into how proteins are organized in a cellular context, with a spatial resolution approaching virtually the molecular level. A unique strength of SMLM is that it delivers molecule-resolved information, along with super-resolved images of cellular structures. This allows quantitative access to cellular structures, for example, how proteins are distributed and organized and how they interact with other biomolecules. Ultimately, it is even possible to determine protein numbers in cells and the number of subunits in a protein complex. SMLM thus has the potential to pave the way toward a better understanding of how cells function at the molecular level. In this review, we describe how SMLM has contributed new knowledge in eukaryotic biology, and we specifically focus on quantitative biological data extracted from SMLM images.}, author = {Sauer, Markus and Heilemann, Mike}, booktitle = {Chemical Reviews}, journal = {Chem. Rev.}, keywords = {sauer}, month = {mar}, publisher = {American Chemical Society}, title = {Single-Molecule Localization Microscopy in Eukaryotes}, year = 2017 }

%0 Journal Article %1 sauer2017singlemolecule %A Sauer, Markus %A Heilemann, Mike %B Chemical Reviews %D 2017 %I American Chemical Society %J Chem. Rev. %R 10.1021/acs.chemrev.6b00667 %T Single-Molecule Localization Microscopy in Eukaryotes %U http://dx.doi.org/10.1021/acs.chemrev.6b00667 %X Super-resolution fluorescence imaging by photoactivation or photoswitching of single fluorophores and position determination (single-molecule localization microscopy, SMLM) provides microscopic images with subdiffraction spatial resolution. This technology has enabled new insights into how proteins are organized in a cellular context, with a spatial resolution approaching virtually the molecular level. A unique strength of SMLM is that it delivers molecule-resolved information, along with super-resolved images of cellular structures. This allows quantitative access to cellular structures, for example, how proteins are distributed and organized and how they interact with other biomolecules. Ultimately, it is even possible to determine protein numbers in cells and the number of subunits in a protein complex. SMLM thus has the potential to pave the way toward a better understanding of how cells function at the molecular level. In this review, we describe how SMLM has contributed new knowledge in eukaryotic biology, and we specifically focus on quantitative biological data extracted from SMLM images.
Characterization of Plasma Membrane Ceramides by Super-Resolution Microscopy Burgert, Anne; Schlegel, Jan; Bécam, Jérôme; Doose, Sören; Bieberich, Erhard; Schubert-Unkmeir, Alexandra; Sauer, Markus in Angewandte Chemie (2017).
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The sphingolipid ceramide regulates cellular processes such as differentiation, proliferation, growth arrest, and apoptosis. Ceramide-rich membrane areas promote structural changes within the plasma membrane that segregate membrane receptors and affect membrane curvature and vesicle formation, fusion, and trafficking. Ceramides were labeled by immunocytochemistry to visualize their distribution on the plasma membrane of different cells with virtually molecular resolution by direct stochastic optical reconstruction microscopy (dSTORM). Super-resolution images show that independent of labeling conditions and cell type 50–60 % of all membrane ceramides are located in ceramide-rich platforms (CRPs) with a size of about 75 nm that are composed of at least about 20 ceramides. Treatment of cells with Bacillus cereus sphingomyelinase (bSMase) increases the overall ceramide concentration in the plasma membrane, the quantity of CRPs, and their size. Simultaneously, the ceramide concentration in CRPs increases approximately twofold.

@article{burgert2017characterization, abstract = {The sphingolipid ceramide regulates cellular processes such as differentiation, proliferation, growth arrest, and apoptosis. Ceramide-rich membrane areas promote structural changes within the plasma membrane that segregate membrane receptors and affect membrane curvature and vesicle formation, fusion, and trafficking. Ceramides were labeled by immunocytochemistry to visualize their distribution on the plasma membrane of different cells with virtually molecular resolution by direct stochastic optical reconstruction microscopy (dSTORM). Super-resolution images show that independent of labeling conditions and cell type 50–60 % of all membrane ceramides are located in ceramide-rich platforms (CRPs) with a size of about 75 nm that are composed of at least about 20 ceramides. Treatment of cells with Bacillus cereus sphingomyelinase (bSMase) increases the overall ceramide concentration in the plasma membrane, the quantity of CRPs, and their size. Simultaneously, the ceramide concentration in CRPs increases approximately twofold.}, author = {Burgert, Anne and Schlegel, Jan and Bécam, Jérôme and Doose, Sören and Bieberich, Erhard and Schubert-Unkmeir, Alexandra and Sauer, Markus}, journal = {Angewandte Chemie}, keywords = {sauer}, title = {Characterization of Plasma Membrane Ceramides by Super-Resolution Microscopy}, year = 2017 }

%0 Journal Article %1 burgert2017characterization %A Burgert, Anne %A Schlegel, Jan %A Bécam, Jérôme %A Doose, Sören %A Bieberich, Erhard %A Schubert-Unkmeir, Alexandra %A Sauer, Markus %D 2017 %J Angewandte Chemie %R 10.1002/ange.201700570 %T Characterization of Plasma Membrane Ceramides by Super-Resolution Microscopy %U http://dx.doi.org/10.1002/ange.201700570 %X The sphingolipid ceramide regulates cellular processes such as differentiation, proliferation, growth arrest, and apoptosis. Ceramide-rich membrane areas promote structural changes within the plasma membrane that segregate membrane receptors and affect membrane curvature and vesicle formation, fusion, and trafficking. Ceramides were labeled by immunocytochemistry to visualize their distribution on the plasma membrane of different cells with virtually molecular resolution by direct stochastic optical reconstruction microscopy (dSTORM). Super-resolution images show that independent of labeling conditions and cell type 50–60 % of all membrane ceramides are located in ceramide-rich platforms (CRPs) with a size of about 75 nm that are composed of at least about 20 ceramides. Treatment of cells with Bacillus cereus sphingomyelinase (bSMase) increases the overall ceramide concentration in the plasma membrane, the quantity of CRPs, and their size. Simultaneously, the ceramide concentration in CRPs increases approximately twofold.
Migration pattern, actin cytoskeleton organization and response to PI3K-, mTOR-, and Hsp90-inhibition of glioblastoma cells with different invasive capacities Memmel, Simon; Sisario, Dmitri; Zöller, Caren; Fiedler, Vanessa; Katzer, Astrid; Heiden, Robin; Becker, Nicholas; Eing, Lorenz; Ferreira, Fábio L.R.; Zimmermann, Heiko; Sauer, Markus; Flentje, Michael; Sukhorukov, Vladimir L.; Djuzenova, Cholpon S. in Oncotarget (2017). 8 45298–45310.
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High invasiveness and resistance to chemo- and radiotherapy of glioblastoma multiforme (GBM) make it the most lethal brain tumor. Therefore, new treatment strategies for preventing migration and invasion of GBM cells are needed. Using two different migration assays, Western blotting, conventional and super-resolution (dSTORM) fluorescence microscopy we examine the effects of the dual PI3K/mTORinhibitor PI-103 alone and in combination with the Hsp90 inhibitor NVP-AUY922 and/or irradiation on the migration, expression of marker proteins, focal adhesions and F-actin cytoskeleton in two GBM cell lines (DK-MG and SNB19) markedly differing in their invasive capacity. Both lines were found to be strikingly different in morphology and migration behavior. The less invasive DK-MG cells maintained a polarized morphology and migrated in a directionally persistent manner, whereas the highly invasive SNB19 cells showed a multipolar morphology and migrated randomly. Interestingly, a single dose of 2 Gy accelerated wound closure in both cell lines without affecting their migration measured by single-cell tracking. PI-103 inhibited migration of DK-MG (p53 wt, PTEN wt) but not of SNB19 (p53 mut, PTEN mut) cells probably due to aberrant reactivation of the PI3K pathway in SNB19 cells treated with PI-103. In contrast, NVP-AUY922 exerted strong anti-migratory effects in both cell lines. Inhibition of cell migration was associated with massive morphological changes and reorganization of the actin cytoskeleton. Our results showed a cell linespecific response to PI3K/mTOR inhibition in terms of GBM cell motility. We conclude that anti-migratory agents warrant further preclinical investigation as potential therapeutics for treatment of GBM.

@article{memmel2017migration, abstract = {High invasiveness and resistance to chemo- and radiotherapy of glioblastoma multiforme (GBM) make it the most lethal brain tumor. Therefore, new treatment strategies for preventing migration and invasion of GBM cells are needed. Using two different migration assays, Western blotting, conventional and super-resolution (dSTORM) fluorescence microscopy we examine the effects of the dual PI3K/mTORinhibitor PI-103 alone and in combination with the Hsp90 inhibitor NVP-AUY922 and/or irradiation on the migration, expression of marker proteins, focal adhesions and F-actin cytoskeleton in two GBM cell lines (DK-MG and SNB19) markedly differing in their invasive capacity. Both lines were found to be strikingly different in morphology and migration behavior. The less invasive DK-MG cells maintained a polarized morphology and migrated in a directionally persistent manner, whereas the highly invasive SNB19 cells showed a multipolar morphology and migrated randomly. Interestingly, a single dose of 2 Gy accelerated wound closure in both cell lines without affecting their migration measured by single-cell tracking. PI-103 inhibited migration of DK-MG (p53 wt, PTEN wt) but not of SNB19 (p53 mut, PTEN mut) cells probably due to aberrant reactivation of the PI3K pathway in SNB19 cells treated with PI-103. In contrast, NVP-AUY922 exerted strong anti-migratory effects in both cell lines. Inhibition of cell migration was associated with massive morphological changes and reorganization of the actin cytoskeleton. Our results showed a cell linespecific response to PI3K/mTOR inhibition in terms of GBM cell motility. We conclude that anti-migratory agents warrant further preclinical investigation as potential therapeutics for treatment of GBM.}, author = {Memmel, Simon and Sisario, Dmitri and Zöller, Caren and Fiedler, Vanessa and Katzer, Astrid and Heiden, Robin and Becker, Nicholas and Eing, Lorenz and Ferreira, Fábio L.R. and Zimmermann, Heiko and Sauer, Markus and Flentje, Michael and Sukhorukov, Vladimir L. and Djuzenova, Cholpon S.}, journal = {Oncotarget}, keywords = {vladimir}, month = {April}, pages = {45298–45310}, title = {Migration pattern, actin cytoskeleton organization and response to PI3K-, mTOR-, and Hsp90-inhibition of glioblastoma cells with different invasive capacities}, volume = 8, year = 2017 }

%0 Journal Article %1 memmel2017migration %A Memmel, Simon %A Sisario, Dmitri %A Zöller, Caren %A Fiedler, Vanessa %A Katzer, Astrid %A Heiden, Robin %A Becker, Nicholas %A Eing, Lorenz %A Ferreira, Fábio L.R. %A Zimmermann, Heiko %A Sauer, Markus %A Flentje, Michael %A Sukhorukov, Vladimir L. %A Djuzenova, Cholpon S. %D 2017 %J Oncotarget %P 45298–45310 %T Migration pattern, actin cytoskeleton organization and response to PI3K-, mTOR-, and Hsp90-inhibition of glioblastoma cells with different invasive capacities %U https://doi.org/10.18632/oncotarget.16847 %V 8 %X High invasiveness and resistance to chemo- and radiotherapy of glioblastoma multiforme (GBM) make it the most lethal brain tumor. Therefore, new treatment strategies for preventing migration and invasion of GBM cells are needed. Using two different migration assays, Western blotting, conventional and super-resolution (dSTORM) fluorescence microscopy we examine the effects of the dual PI3K/mTORinhibitor PI-103 alone and in combination with the Hsp90 inhibitor NVP-AUY922 and/or irradiation on the migration, expression of marker proteins, focal adhesions and F-actin cytoskeleton in two GBM cell lines (DK-MG and SNB19) markedly differing in their invasive capacity. Both lines were found to be strikingly different in morphology and migration behavior. The less invasive DK-MG cells maintained a polarized morphology and migrated in a directionally persistent manner, whereas the highly invasive SNB19 cells showed a multipolar morphology and migrated randomly. Interestingly, a single dose of 2 Gy accelerated wound closure in both cell lines without affecting their migration measured by single-cell tracking. PI-103 inhibited migration of DK-MG (p53 wt, PTEN wt) but not of SNB19 (p53 mut, PTEN mut) cells probably due to aberrant reactivation of the PI3K pathway in SNB19 cells treated with PI-103. In contrast, NVP-AUY922 exerted strong anti-migratory effects in both cell lines. Inhibition of cell migration was associated with massive morphological changes and reorganization of the actin cytoskeleton. Our results showed a cell linespecific response to PI3K/mTOR inhibition in terms of GBM cell motility. We conclude that anti-migratory agents warrant further preclinical investigation as potential therapeutics for treatment of GBM.
Conservation of folding and association within a family of spidroin N-terminal domains Heiby, Julia C.; Rajab, Suhaila; Rat, Charlotte; Johnson, Christopher M.; Neuweiler, Hannes in Scientific Reports (2017). 7(1) 16789.
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Web spiders synthesize silk fibres, nature’s toughest biomaterial, through the controlled assembly of fibroin proteins, so-called spidroins. The highly conserved spidroin N-terminal domain (NTD) is a pH-driven self-assembly device that connects spidroins to super-molecules in fibres. The degree to which forces of self-assembly is conserved across spider glands and species is currently unknown because quantitative measures are missing. Here, we report the comparative investigation of spidroin NTDs originating from the major ampullate glands of the spider species Euprosthenops australis, Nephila clavipes, Latrodectus hesperus, and Latrodectus geometricus. We characterized equilibrium thermodynamics and kinetics of folding and self-association using dynamic light scattering, stopped-flow fluorescence and circular dichroism spectroscopy in combination with thermal and chemical denaturation experiments. We found cooperative two-state folding on a sub-millisecond time scale through a late transition state of all four domains. Stability was compromised by repulsive electrostatic forces originating from clustering of point charges on the NTD surface required for function. pH-driven dimerization proceeded with characteristic fast kinetics yielding high affinities. Results showed that energetics and kinetics of NTD self-assembly are highly conserved across spider species despite the different silk mechanical properties and web geometries they produce.

@article{heiby2017conservation, abstract = {Web spiders synthesize silk fibres, nature’s toughest biomaterial, through the controlled assembly of fibroin proteins, so-called spidroins. The highly conserved spidroin N-terminal domain (NTD) is a pH-driven self-assembly device that connects spidroins to super-molecules in fibres. The degree to which forces of self-assembly is conserved across spider glands and species is currently unknown because quantitative measures are missing. Here, we report the comparative investigation of spidroin NTDs originating from the major ampullate glands of the spider species Euprosthenops australis, Nephila clavipes, Latrodectus hesperus, and Latrodectus geometricus. We characterized equilibrium thermodynamics and kinetics of folding and self-association using dynamic light scattering, stopped-flow fluorescence and circular dichroism spectroscopy in combination with thermal and chemical denaturation experiments. We found cooperative two-state folding on a sub-millisecond time scale through a late transition state of all four domains. Stability was compromised by repulsive electrostatic forces originating from clustering of point charges on the NTD surface required for function. pH-driven dimerization proceeded with characteristic fast kinetics yielding high affinities. Results showed that energetics and kinetics of NTD self-assembly are highly conserved across spider species despite the different silk mechanical properties and web geometries they produce.}, author = {Heiby, Julia C. and Rajab, Suhaila and Rat, Charlotte and Johnson, Christopher M. and Neuweiler, Hannes}, journal = {Scientific Reports}, keywords = {hannes}, month = 12, number = 1, pages = 16789, publisher = {Nature Publishing Group}, title = {Conservation of folding and association within a family of spidroin N-terminal domains}, volume = 7, year = 2017 }

%0 Journal Article %1 heiby2017conservation %A Heiby, Julia C. %A Rajab, Suhaila %A Rat, Charlotte %A Johnson, Christopher M. %A Neuweiler, Hannes %D 2017 %I Nature Publishing Group %J Scientific Reports %N 1 %P 16789 %R 10.1038/s41598-017-16881-6 %T Conservation of folding and association within a family of spidroin N-terminal domains %U https://doi.org/10.1038/s41598-017-16881-6 %V 7 %X Web spiders synthesize silk fibres, nature’s toughest biomaterial, through the controlled assembly of fibroin proteins, so-called spidroins. The highly conserved spidroin N-terminal domain (NTD) is a pH-driven self-assembly device that connects spidroins to super-molecules in fibres. The degree to which forces of self-assembly is conserved across spider glands and species is currently unknown because quantitative measures are missing. Here, we report the comparative investigation of spidroin NTDs originating from the major ampullate glands of the spider species Euprosthenops australis, Nephila clavipes, Latrodectus hesperus, and Latrodectus geometricus. We characterized equilibrium thermodynamics and kinetics of folding and self-association using dynamic light scattering, stopped-flow fluorescence and circular dichroism spectroscopy in combination with thermal and chemical denaturation experiments. We found cooperative two-state folding on a sub-millisecond time scale through a late transition state of all four domains. Stability was compromised by repulsive electrostatic forces originating from clustering of point charges on the NTD surface required for function. pH-driven dimerization proceeded with characteristic fast kinetics yielding high affinities. Results showed that energetics and kinetics of NTD self-assembly are highly conserved across spider species despite the different silk mechanical properties and web geometries they produce.
Gephyrin-binding peptides visualize postsynaptic sites and modulate neurotransmission Maric, Hans Michael; Hausrat, Torben Johann; Neubert, Franziska; Dalby, Nils Ole; Doose, Sören; Sauer, Markus; Kneussel, Matthias; Strømgaard, Kristian in Nature Chemical Biology (2017). 13 153-.
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γ-Aminobutyric acid type A and glycine receptors are the major mediators of fast synaptic inhibition in the human central nervous system and are established drug targets. However, all drugs targeting these receptors bind to the extracellular ligand-binding domain of the receptors, which inherently is associated with perturbation of the basic physiological action. Here we pursue a fundamentally different approach, by instead targeting the intracellular receptor–gephyrin interaction. First, we defined the gephyrin peptide-binding consensus sequence, which facilitated the development of gephyrin super-binding peptides and later effective affinity probes for the isolation of native gephyrin. Next, we demonstrated that fluorescent super-binding peptides could be used to directly visualize inhibitory postsynaptic sites for the first time in conventional and super-resolution microscopy. Finally, we demonstrate that the gephyrin super-binding peptides act as acute intracellular modulators of fast synaptic inhibition by modulating receptor clustering, thus being conceptually novel modulators of inhibitory neurotransmission.

@article{maric2016gephyrinbinding, abstract = {γ-Aminobutyric acid type A and glycine receptors are the major mediators of fast synaptic inhibition in the human central nervous system and are established drug targets. However, all drugs targeting these receptors bind to the extracellular ligand-binding domain of the receptors, which inherently is associated with perturbation of the basic physiological action. Here we pursue a fundamentally different approach, by instead targeting the intracellular receptor–gephyrin interaction. First, we defined the gephyrin peptide-binding consensus sequence, which facilitated the development of gephyrin super-binding peptides and later effective affinity probes for the isolation of native gephyrin. Next, we demonstrated that fluorescent super-binding peptides could be used to directly visualize inhibitory postsynaptic sites for the first time in conventional and super-resolution microscopy. Finally, we demonstrate that the gephyrin super-binding peptides act as acute intracellular modulators of fast synaptic inhibition by modulating receptor clustering, thus being conceptually novel modulators of inhibitory neurotransmission.}, author = {Maric, Hans Michael and Hausrat, Torben Johann and Neubert, Franziska and Dalby, Nils Ole and Doose, Sören and Sauer, Markus and Kneussel, Matthias and Strømgaard, Kristian}, journal = {Nature Chemical Biology}, keywords = {sauer}, month = {nov}, pages = {153–}, publisher = {Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.}, title = {Gephyrin-binding peptides visualize postsynaptic sites and modulate neurotransmission}, volume = 13, year = 2017 }

%0 Journal Article %1 maric2016gephyrinbinding %A Maric, Hans Michael %A Hausrat, Torben Johann %A Neubert, Franziska %A Dalby, Nils Ole %A Doose, Sören %A Sauer, Markus %A Kneussel, Matthias %A Strømgaard, Kristian %D 2017 %I Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved. %J Nature Chemical Biology %P 153-- %T Gephyrin-binding peptides visualize postsynaptic sites and modulate neurotransmission %U https://doi.org/10.1038/nchembio.2246 %V 13 %X γ-Aminobutyric acid type A and glycine receptors are the major mediators of fast synaptic inhibition in the human central nervous system and are established drug targets. However, all drugs targeting these receptors bind to the extracellular ligand-binding domain of the receptors, which inherently is associated with perturbation of the basic physiological action. Here we pursue a fundamentally different approach, by instead targeting the intracellular receptor–gephyrin interaction. First, we defined the gephyrin peptide-binding consensus sequence, which facilitated the development of gephyrin super-binding peptides and later effective affinity probes for the isolation of native gephyrin. Next, we demonstrated that fluorescent super-binding peptides could be used to directly visualize inhibitory postsynaptic sites for the first time in conventional and super-resolution microscopy. Finally, we demonstrate that the gephyrin super-binding peptides act as acute intracellular modulators of fast synaptic inhibition by modulating receptor clustering, thus being conceptually novel modulators of inhibitory neurotransmission.
Cell culture media supplemented with raffinose reproducibly enhances high mannose glycan formation Brühlmann, David; Muhr, Anais; Parker, Rebecca; Vuillemin, Thomas; Bucsella, Blanka; Kalman, Franka; Torre, Serena; La Neve, Fabio; Lembo, Antonio; Haas, Tobias; Sauer, Markus; Souquet, Jonathan; Broly, Hervé; Hemberger, Jürgen; Jordan, Martin in Journal of Biotechnology (2017). 252(Supplement C) 32–42.
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Glycosylation plays a pivotal role in pharmacokinetics and protein physiochemical characteristics. In particular, effector functions including antibody-dependent cell-mediated cytotoxicity (ADCC) can be desired, and it has been described that high-mannose species exhibited enhanced ADCC. In this work we present the trisaccharide raffinose as a novel cell culture medium supplement to promote high mannose N-glycans in fed-batch cultures, which is sought after in the development of biosimilars to match the quality profile of the reference medicinal product (RMP) also. Up to six-fold increases of high mannose species were observed with increasing raffinose concentrations in the medium of shaken 96-deepwell plates and shake tubes when culturing two different CHO cell lines in two different media. The findings were confirmed in a pH-, oxygen- and CO2-controlled environment in lab-scale 3.5-L bioreactors. To circumvent detrimental effects on cell growth and productivity at high raffinose concentrations, the media osmolality was adjusted to reach the same value independently of the supplement concentration. Interestingly, raffinose predominantly enhanced mannose 5 glycans, and to a considerably smaller degree, mannose 6. While the underlying mechanism is still not fully understood, minor effects on the nucleotide sugar levels have been observed and transcriptomics analysis revealed that raffinose supplementation altered the expression levels of a number of glycosylation related genes. Among many genes, galactosyltransferase was downregulated and sialyltransferase upregulated. Our results highlight the potential of cell culture medium supplementation to modulate product quality.

@article{bruhlmann2017culture, abstract = {Glycosylation plays a pivotal role in pharmacokinetics and protein physiochemical characteristics. In particular, effector functions including antibody-dependent cell-mediated cytotoxicity (ADCC) can be desired, and it has been described that high-mannose species exhibited enhanced ADCC. In this work we present the trisaccharide raffinose as a novel cell culture medium supplement to promote high mannose N-glycans in fed-batch cultures, which is sought after in the development of biosimilars to match the quality profile of the reference medicinal product (RMP) also. Up to six-fold increases of high mannose species were observed with increasing raffinose concentrations in the medium of shaken 96-deepwell plates and shake tubes when culturing two different CHO cell lines in two different media. The findings were confirmed in a pH-, oxygen- and CO2-controlled environment in lab-scale 3.5-L bioreactors. To circumvent detrimental effects on cell growth and productivity at high raffinose concentrations, the media osmolality was adjusted to reach the same value independently of the supplement concentration. Interestingly, raffinose predominantly enhanced mannose 5 glycans, and to a considerably smaller degree, mannose 6. While the underlying mechanism is still not fully understood, minor effects on the nucleotide sugar levels have been observed and transcriptomics analysis revealed that raffinose supplementation altered the expression levels of a number of glycosylation related genes. Among many genes, galactosyltransferase was downregulated and sialyltransferase upregulated. Our results highlight the potential of cell culture medium supplementation to modulate product quality.}, author = {Brühlmann, David and Muhr, Anais and Parker, Rebecca and Vuillemin, Thomas and Bucsella, Blanka and Kalman, Franka and Torre, Serena and La Neve, Fabio and Lembo, Antonio and Haas, Tobias and Sauer, Markus and Souquet, Jonathan and Broly, Hervé and Hemberger, Jürgen and Jordan, Martin}, journal = {Journal of Biotechnology}, keywords = {sauer}, number = {Supplement C}, pages = {32–42}, title = {Cell culture media supplemented with raffinose reproducibly enhances high mannose glycan formation}, volume = 252, year = 2017 }

%0 Journal Article %1 bruhlmann2017culture %A Brühlmann, David %A Muhr, Anais %A Parker, Rebecca %A Vuillemin, Thomas %A Bucsella, Blanka %A Kalman, Franka %A Torre, Serena %A La Neve, Fabio %A Lembo, Antonio %A Haas, Tobias %A Sauer, Markus %A Souquet, Jonathan %A Broly, Hervé %A Hemberger, Jürgen %A Jordan, Martin %D 2017 %J Journal of Biotechnology %N Supplement C %P 32--42 %R https://doi.org/10.1016/j.jbiotec.2017.04.026 %T Cell culture media supplemented with raffinose reproducibly enhances high mannose glycan formation %U http://www.sciencedirect.com/science/article/pii/S016816561730189X %V 252 %X Glycosylation plays a pivotal role in pharmacokinetics and protein physiochemical characteristics. In particular, effector functions including antibody-dependent cell-mediated cytotoxicity (ADCC) can be desired, and it has been described that high-mannose species exhibited enhanced ADCC. In this work we present the trisaccharide raffinose as a novel cell culture medium supplement to promote high mannose N-glycans in fed-batch cultures, which is sought after in the development of biosimilars to match the quality profile of the reference medicinal product (RMP) also. Up to six-fold increases of high mannose species were observed with increasing raffinose concentrations in the medium of shaken 96-deepwell plates and shake tubes when culturing two different CHO cell lines in two different media. The findings were confirmed in a pH-, oxygen- and CO2-controlled environment in lab-scale 3.5-L bioreactors. To circumvent detrimental effects on cell growth and productivity at high raffinose concentrations, the media osmolality was adjusted to reach the same value independently of the supplement concentration. Interestingly, raffinose predominantly enhanced mannose 5 glycans, and to a considerably smaller degree, mannose 6. While the underlying mechanism is still not fully understood, minor effects on the nucleotide sugar levels have been observed and transcriptomics analysis revealed that raffinose supplementation altered the expression levels of a number of glycosylation related genes. Among many genes, galactosyltransferase was downregulated and sialyltransferase upregulated. Our results highlight the potential of cell culture medium supplementation to modulate product quality.
Chapter 2 - 3D subcellular localization with superresolution array tomography on ultrathin sections of various species Markert, Sebastian M.; Bauer, Vivien; Muenz, Thomas S.; Jones, Nicola G.; Helmprobst, Frederik; Britz, Sebastian; Sauer, Markus; Rössler, Wolfgang; Engstler, Markus; Stigloher, Christian in Correlative Light and Electron Microscopy III, T. Müller-Reichert, P. Verkade (Hrsg.) (2017). (Bd. 140) 21–47.
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Array Tomography (AT) is a relatively easy-to-use and yet powerful method to put molecular identity in its full ultrastructural context. Ultrathin sections are stained with fluorophores and then imaged by light and afterward by electron microscopy to obtain a correlated view of a region of interest: its ultrastructure and specific staining. By combining AT with high-pressure freezing for superior structural preservation and superresolution light microscopy, even small subcellular structures can be mapped in 3D. We established protocols for the application of superresolution AT on ultrathin plastic sections of Caenorhabditis elegans, Trypanosoma brucei, and brain tissue of Cataglyphis fortis and Apis mellifera. All steps are described in detail from sample preparation to 3D reconstruction, including species-specific modifications. We thus showcase the versatility of our protocol and give some examples for biological questions that can be answered with this technique. We offer a step-by-step recipe for superresolution AT that can be easily applied for C. elegans, T. brucei, C. fortis, and A. mellifera and adapted for other model systems.

@inbook{markert2017chapter, abstract = {Array Tomography (AT) is a relatively easy-to-use and yet powerful method to put molecular identity in its full ultrastructural context. Ultrathin sections are stained with fluorophores and then imaged by light and afterward by electron microscopy to obtain a correlated view of a region of interest: its ultrastructure and specific staining. By combining AT with high-pressure freezing for superior structural preservation and superresolution light microscopy, even small subcellular structures can be mapped in 3D. We established protocols for the application of superresolution AT on ultrathin plastic sections of Caenorhabditis elegans, Trypanosoma brucei, and brain tissue of Cataglyphis fortis and Apis mellifera. All steps are described in detail from sample preparation to 3D reconstruction, including species-specific modifications. We thus showcase the versatility of our protocol and give some examples for biological questions that can be answered with this technique. We offer a step-by-step recipe for superresolution AT that can be easily applied for C. elegans, T. brucei, C. fortis, and A. mellifera and adapted for other model systems.}, author = {Markert, Sebastian M. and Bauer, Vivien and Muenz, Thomas S. and Jones, Nicola G. and Helmprobst, Frederik and Britz, Sebastian and Sauer, Markus and Rössler, Wolfgang and Engstler, Markus and Stigloher, Christian}, booktitle = {Correlative Light and Electron Microscopy III}, editor = {Müller-Reichert, Thomas and Verkade, Paul}, keywords = {sauer}, number = {Supplement C}, pages = {21–47}, publisher = {Academic Press}, title = {Chapter 2 - 3D subcellular localization with superresolution array tomography on ultrathin sections of various species}, volume = 140, year = 2017 }

%0 Book Section %1 markert2017chapter %A Markert, Sebastian M. %A Bauer, Vivien %A Muenz, Thomas S. %A Jones, Nicola G. %A Helmprobst, Frederik %A Britz, Sebastian %A Sauer, Markus %A Rössler, Wolfgang %A Engstler, Markus %A Stigloher, Christian %B Correlative Light and Electron Microscopy III %D 2017 %E Müller-Reichert, Thomas %E Verkade, Paul %I Academic Press %N Supplement C %P 21--47 %R https://doi.org/10.1016/bs.mcb.2017.03.004 %T Chapter 2 - 3D subcellular localization with superresolution array tomography on ultrathin sections of various species %U http://www.sciencedirect.com/science/article/pii/S0091679X17300481 %V 140 %X Array Tomography (AT) is a relatively easy-to-use and yet powerful method to put molecular identity in its full ultrastructural context. Ultrathin sections are stained with fluorophores and then imaged by light and afterward by electron microscopy to obtain a correlated view of a region of interest: its ultrastructure and specific staining. By combining AT with high-pressure freezing for superior structural preservation and superresolution light microscopy, even small subcellular structures can be mapped in 3D. We established protocols for the application of superresolution AT on ultrathin plastic sections of Caenorhabditis elegans, Trypanosoma brucei, and brain tissue of Cataglyphis fortis and Apis mellifera. All steps are described in detail from sample preparation to 3D reconstruction, including species-specific modifications. We thus showcase the versatility of our protocol and give some examples for biological questions that can be answered with this technique. We offer a step-by-step recipe for superresolution AT that can be easily applied for C. elegans, T. brucei, C. fortis, and A. mellifera and adapted for other model systems.

2016[ to top ]

Photometry unlocks 3D information from 2D localization microscopy data Franke, Christian; Sauer, Markus; van de Linde, Sebastian in Nat Meth (2016). advance online publication
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We developed a straightforward photometric method, temporal, radial-aperture-based intensity estimation (TRABI), that allows users to extract 3D information from existing 2D localization microscopy data. TRABI uses the accurate determination of photon numbers in different regions of the emission pattern of single emitters to generate a z-dependent photometric parameter. This method can determine fluorophore positions up to 600 nm from the focal plane and can be combined with biplane detection to further improve axial localization.

@article{franke2016photometry, abstract = {We developed a straightforward photometric method, temporal, radial-aperture-based intensity estimation (TRABI), that allows users to extract 3D information from existing 2D localization microscopy data. TRABI uses the accurate determination of photon numbers in different regions of the emission pattern of single emitters to generate a z-dependent photometric parameter. This method can determine fluorophore positions up to 600 nm from the focal plane and can be combined with biplane detection to further improve axial localization.}, author = {Franke, Christian and Sauer, Markus and van de Linde, Sebastian}, journal = {Nat Meth}, keywords = {sauer}, month = {nov}, publisher = {Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.}, title = {Photometry unlocks 3D information from 2D localization microscopy data}, volume = {advance online publication}, year = 2016 }

%0 Journal Article %1 franke2016photometry %A Franke, Christian %A Sauer, Markus %A van de Linde, Sebastian %D 2016 %I Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved. %J Nat Meth %T Photometry unlocks 3D information from 2D localization microscopy data %U http://dx.doi.org/10.1038/nmeth.4073 %V advance online publication %X We developed a straightforward photometric method, temporal, radial-aperture-based intensity estimation (TRABI), that allows users to extract 3D information from existing 2D localization microscopy data. TRABI uses the accurate determination of photon numbers in different regions of the emission pattern of single emitters to generate a z-dependent photometric parameter. This method can determine fluorophore positions up to 600 nm from the focal plane and can be combined with biplane detection to further improve axial localization.
Multi-target spectrally resolved fluorescence lifetime imaging microscopy Niehorster, Thomas; Loschberger, Anna; Gregor, Ingo; Kramer, Benedikt; Rahn, Hans-Jurgen; Patting, Matthias; Koberling, Felix; Enderlein, Jorg; Sauer, Markus in Nat Meth (2016). advance online publication
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We introduce a pattern-matching technique for efficient identification of fluorophore ratios in complex multidimensional fluorescence signals using reference fluorescence decay and spectral signature patterns of individual fluorescent probes. Alternating pulsed laser excitation at three different wavelengths and time-resolved detection on 32 spectrally separated detection channels ensures efficient excitation of fluorophores and a maximum gain of fluorescence information. Using spectrally resolved fluorescence lifetime imaging microscopy (sFLIM), we were able to visualize up to nine different target molecules simultaneously in mouse C2C12 cells. By exploiting the sensitivity of fluorescence emission spectra and the lifetime of organic fluorophores on environmental factors, we carried out fluorescence imaging of three different target molecules in human U2OS cells with the same fluorophore. Our results demonstrate that sFLIM can be used for super-resolution multi-target imaging by stimulated emission depletion (STED).

@article{niehorster2016multitarget, abstract = {We introduce a pattern-matching technique for efficient identification of fluorophore ratios in complex multidimensional fluorescence signals using reference fluorescence decay and spectral signature patterns of individual fluorescent probes. Alternating pulsed laser excitation at three different wavelengths and time-resolved detection on 32 spectrally separated detection channels ensures efficient excitation of fluorophores and a maximum gain of fluorescence information. Using spectrally resolved fluorescence lifetime imaging microscopy (sFLIM), we were able to visualize up to nine different target molecules simultaneously in mouse C2C12 cells. By exploiting the sensitivity of fluorescence emission spectra and the lifetime of organic fluorophores on environmental factors, we carried out fluorescence imaging of three different target molecules in human U2OS cells with the same fluorophore. Our results demonstrate that sFLIM can be used for super-resolution multi-target imaging by stimulated emission depletion (STED).}, author = {Niehorster, Thomas and Loschberger, Anna and Gregor, Ingo and Kramer, Benedikt and Rahn, Hans-Jurgen and Patting, Matthias and Koberling, Felix and Enderlein, Jorg and Sauer, Markus}, journal = {Nat Meth}, keywords = {sauer}, month = {jan}, publisher = {Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.}, title = {Multi-target spectrally resolved fluorescence lifetime imaging microscopy}, volume = {advance online publication}, year = 2016 }

%0 Journal Article %1 niehorster2016multitarget %A Niehorster, Thomas %A Loschberger, Anna %A Gregor, Ingo %A Kramer, Benedikt %A Rahn, Hans-Jurgen %A Patting, Matthias %A Koberling, Felix %A Enderlein, Jorg %A Sauer, Markus %D 2016 %I Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved. %J Nat Meth %T Multi-target spectrally resolved fluorescence lifetime imaging microscopy %U http://dx.doi.org/10.1038/nmeth.3740 %V advance online publication %X We introduce a pattern-matching technique for efficient identification of fluorophore ratios in complex multidimensional fluorescence signals using reference fluorescence decay and spectral signature patterns of individual fluorescent probes. Alternating pulsed laser excitation at three different wavelengths and time-resolved detection on 32 spectrally separated detection channels ensures efficient excitation of fluorophores and a maximum gain of fluorescence information. Using spectrally resolved fluorescence lifetime imaging microscopy (sFLIM), we were able to visualize up to nine different target molecules simultaneously in mouse C2C12 cells. By exploiting the sensitivity of fluorescence emission spectra and the lifetime of organic fluorophores on environmental factors, we carried out fluorescence imaging of three different target molecules in human U2OS cells with the same fluorophore. Our results demonstrate that sFLIM can be used for super-resolution multi-target imaging by stimulated emission depletion (STED).
Dual PI3K- and mTOR-inhibitor PI-103 can either enhance or reduce the radiosensitizing effect of the Hsp90 inhibitor NVP-AUY922 in tumor cells: The role of drug-irradiation schedule Djuzenova, Cholpon; Fiedler, Vanessa; Katzer, Astrid; Michel, Konstanze; Deckert, Stefanie; Zimmermann, Heiko; Sukhorukov, Vladimir; Flentje, Michael in Oncotarget (2016). 5
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Inhibition of Hsp90 can increase the radiosensitivity of tumor cells. However, inhibition of Hsp90 alone induces the anti-apoptotic Hsp70 and thereby decreases radiosensitivity. Therefore, preventing Hsp70 induction can be a promising strategy for radiosensitization. PI-103, an inhibitor of PI3K and mTOR, has previously been shown to suppress the up-regulation of Hsp70. Here, we explore the impact of combining PI-103 with the Hsp90 inhibitor NVP-AUY922 in irradiated glioblastoma and colon carcinoma cells. We analyzed the cellular response to drug-irradiation treatments by colony-forming assay, expression of several marker proteins, cell cycle progression and induction/repair of DNA damage. Although PI-103, given 24 h prior to irradiation, slightly suppressed the NVP-AUY922-mediated up-regulation of Hsp70, it did not cause radiosensitization and even diminished the radiosensitizing effect of NVP-AUY922. This result can be explained by the activation of PI3K and ERK pathways along with G1-arrest at the time of irradiation. In sharp contrast, PI-103 not only exerted a radiosensitizing effect but also strongly enhanced the radiosensitization by NVP-AUY922 when both inhibitors were added 3 h before irradiation and kept in culture for 24 h. Possible reasons for the observed radiosensitization under this drug-irradiation schedule may be a down-regulation of PI3K and ERK pathways during or directly after irradiation, increased residual DNA damage and strong G2/M arrest 24 h thereafter. We conclude that duration of drug treatment before irradiation plays a key role in the concomitant targeting of PI3K/mTOR and Hsp90 in tumor cells

@article{OT9501, abstract = {Inhibition of Hsp90 can increase the radiosensitivity of tumor cells. However, inhibition of Hsp90 alone induces the anti-apoptotic Hsp70 and thereby decreases radiosensitivity. Therefore, preventing Hsp70 induction can be a promising strategy for radiosensitization. PI-103, an inhibitor of PI3K and mTOR, has previously been shown to suppress the up-regulation of Hsp70. Here, we explore the impact of combining PI-103 with the Hsp90 inhibitor NVP-AUY922 in irradiated glioblastoma and colon carcinoma cells. We analyzed the cellular response to drug-irradiation treatments by colony-forming assay, expression of several marker proteins, cell cycle progression and induction/repair of DNA damage. Although PI-103, given 24 h prior to irradiation, slightly suppressed the NVP-AUY922-mediated up-regulation of Hsp70, it did not cause radiosensitization and even diminished the radiosensitizing effect of NVP-AUY922. This result can be explained by the activation of PI3K and ERK pathways along with G1-arrest at the time of irradiation. In sharp contrast, PI-103 not only exerted a radiosensitizing effect but also strongly enhanced the radiosensitization by NVP-AUY922 when both inhibitors were added 3 h before irradiation and kept in culture for 24 h. Possible reasons for the observed radiosensitization under this drug-irradiation schedule may be a down-regulation of PI3K and ERK pathways during or directly after irradiation, increased residual DNA damage and strong G2/M arrest 24 h thereafter. We conclude that duration of drug treatment before irradiation plays a key role in the concomitant targeting of PI3K/mTOR and Hsp90 in tumor cells}, author = {Djuzenova, Cholpon and Fiedler, Vanessa and Katzer, Astrid and Michel, Konstanze and Deckert, Stefanie and Zimmermann, Heiko and Sukhorukov, Vladimir and Flentje, Michael}, journal = {Oncotarget}, keywords = {vladimir}, title = {Dual PI3K- and mTOR-inhibitor PI-103 can either enhance or reduce the radiosensitizing effect of the Hsp90 inhibitor NVP-AUY922 in tumor cells: The role of drug-irradiation schedule}, volume = 5, year = 2016 }

%0 Journal Article %1 OT9501 %A Djuzenova, Cholpon %A Fiedler, Vanessa %A Katzer, Astrid %A Michel, Konstanze %A Deckert, Stefanie %A Zimmermann, Heiko %A Sukhorukov, Vladimir %A Flentje, Michael %D 2016 %J Oncotarget %T Dual PI3K- and mTOR-inhibitor PI-103 can either enhance or reduce the radiosensitizing effect of the Hsp90 inhibitor NVP-AUY922 in tumor cells: The role of drug-irradiation schedule %U http://www.ncbi.nlm.nih.gov/pubmed/27224913 %V 5 %X Inhibition of Hsp90 can increase the radiosensitivity of tumor cells. However, inhibition of Hsp90 alone induces the anti-apoptotic Hsp70 and thereby decreases radiosensitivity. Therefore, preventing Hsp70 induction can be a promising strategy for radiosensitization. PI-103, an inhibitor of PI3K and mTOR, has previously been shown to suppress the up-regulation of Hsp70. Here, we explore the impact of combining PI-103 with the Hsp90 inhibitor NVP-AUY922 in irradiated glioblastoma and colon carcinoma cells. We analyzed the cellular response to drug-irradiation treatments by colony-forming assay, expression of several marker proteins, cell cycle progression and induction/repair of DNA damage. Although PI-103, given 24 h prior to irradiation, slightly suppressed the NVP-AUY922-mediated up-regulation of Hsp70, it did not cause radiosensitization and even diminished the radiosensitizing effect of NVP-AUY922. This result can be explained by the activation of PI3K and ERK pathways along with G1-arrest at the time of irradiation. In sharp contrast, PI-103 not only exerted a radiosensitizing effect but also strongly enhanced the radiosensitization by NVP-AUY922 when both inhibitors were added 3 h before irradiation and kept in culture for 24 h. Possible reasons for the observed radiosensitization under this drug-irradiation schedule may be a down-regulation of PI3K and ERK pathways during or directly after irradiation, increased residual DNA damage and strong G2/M arrest 24 h thereafter. We conclude that duration of drug treatment before irradiation plays a key role in the concomitant targeting of PI3K/mTOR and Hsp90 in tumor cells
Reconstruction of the high-osmolarity glycerol (HOG) signaling pathway from the halophilic fungus Wallemia ichthyophaga in Saccharomyces cerevisiae Konte, Tilen; Terpitz, Ulrich; Plemenitas, Ana in Frontiers in Microbiology (2016). 7(901)
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The basidiomycetous fungus Wallemia ichthyophaga grows between 1.7 M and 5.1 M NaCl and is the most halophilic eukaryote described to date. Like in other fungi, in W. ichthyophaga, changes in environmental salinity are detected mainly by the evolutionarily conserved high-osmolarity glycerol (HOG) signaling pathway. In Saccharomyces cerevisiae, the HOG pathway has been extensively studied in connection to osmotic regulation, with a valuable knock-out strain collection established. In the present study, we reconstructed the architecture of the HOG pathway of W. ichthyophaga in suitable S. cerevisiae knock-out strains, through heterologous expression of the W. ichthyophaga HOG pathway proteins. Compared to S. cerevisiae, where the Pbs2 (ScPbs2) kinase of the HOG pathway is activated via the SHO1 and SLN1 branches, the interactions between the W. ichthyophaga Pbs2 (WiPbs2) kinase and the W. ichthyophaga SHO1 branch orthologs are not conserved: as well as evidence of poor interactions between the WiSho1 Src-homology 3 (SH3) domain and the WiPbs2 proline-rich motif, the absence of a considerable part of the osmosensing apparatus in the genome of W. ichthyophaga suggests that the SHO1 branch components are not involved in HOG signaling in this halophilic fungus. In contrast, the conserved activation of WiPbs2 by the S. cerevisiae ScSsk2/ScSsk22 kinase and the sensitivity of W. ichthyophaga cells to fludioxonil, emphasize the significance of two-component (SLN1-like) signaling via Group III histidine kinase. Combined with the protein modeling data, our study reveals conserved and nonconserved protein interactions in the HOG signaling pathway of W. ichthyophaga and therefore significantly improves the knowledge of hyperosmotic signal processing in this halophilic fungus.

@article{10.3389/fmicb.2016.00901, abstract = {The basidiomycetous fungus Wallemia ichthyophaga grows between 1.7 M and 5.1 M NaCl and is the most halophilic eukaryote described to date. Like in other fungi, in W. ichthyophaga, changes in environmental salinity are detected mainly by the evolutionarily conserved high-osmolarity glycerol (HOG) signaling pathway. In Saccharomyces cerevisiae, the HOG pathway has been extensively studied in connection to osmotic regulation, with a valuable knock-out strain collection established. In the present study, we reconstructed the architecture of the HOG pathway of W. ichthyophaga in suitable S. cerevisiae knock-out strains, through heterologous expression of the W. ichthyophaga HOG pathway proteins. Compared to S. cerevisiae, where the Pbs2 (ScPbs2) kinase of the HOG pathway is activated via the SHO1 and SLN1 branches, the interactions between the W. ichthyophaga Pbs2 (WiPbs2) kinase and the W. ichthyophaga SHO1 branch orthologs are not conserved: as well as evidence of poor interactions between the WiSho1 Src-homology 3 (SH3) domain and the WiPbs2 proline-rich motif, the absence of a considerable part of the osmosensing apparatus in the genome of W. ichthyophaga suggests that the SHO1 branch components are not involved in HOG signaling in this halophilic fungus. In contrast, the conserved activation of WiPbs2 by the S. cerevisiae ScSsk2/ScSsk22 kinase and the sensitivity of W. ichthyophaga cells to fludioxonil, emphasize the significance of two-component (SLN1-like) signaling via Group III histidine kinase. Combined with the protein modeling data, our study reveals conserved and nonconserved protein interactions in the HOG signaling pathway of W. ichthyophaga and therefore significantly improves the knowledge of hyperosmotic signal processing in this halophilic fungus.}, author = {Konte, Tilen and Terpitz, Ulrich and Plemenitas, Ana}, journal = {Frontiers in Microbiology}, keywords = {terpitz}, number = 901, title = {Reconstruction of the high-osmolarity glycerol (HOG) signaling pathway from the halophilic fungus Wallemia ichthyophaga in Saccharomyces cerevisiae}, volume = 7, year = 2016 }

%0 Journal Article %1 10.3389/fmicb.2016.00901 %A Konte, Tilen %A Terpitz, Ulrich %A Plemenitas, Ana %D 2016 %J Frontiers in Microbiology %N 901 %R 10.3389/fmicb.2016.00901 %T Reconstruction of the high-osmolarity glycerol (HOG) signaling pathway from the halophilic fungus Wallemia ichthyophaga in Saccharomyces cerevisiae %U http://www.frontiersin.org/extreme_microbiology/10.3389/fmicb.2016.00901/abstract %V 7 %X The basidiomycetous fungus Wallemia ichthyophaga grows between 1.7 M and 5.1 M NaCl and is the most halophilic eukaryote described to date. Like in other fungi, in W. ichthyophaga, changes in environmental salinity are detected mainly by the evolutionarily conserved high-osmolarity glycerol (HOG) signaling pathway. In Saccharomyces cerevisiae, the HOG pathway has been extensively studied in connection to osmotic regulation, with a valuable knock-out strain collection established. In the present study, we reconstructed the architecture of the HOG pathway of W. ichthyophaga in suitable S. cerevisiae knock-out strains, through heterologous expression of the W. ichthyophaga HOG pathway proteins. Compared to S. cerevisiae, where the Pbs2 (ScPbs2) kinase of the HOG pathway is activated via the SHO1 and SLN1 branches, the interactions between the W. ichthyophaga Pbs2 (WiPbs2) kinase and the W. ichthyophaga SHO1 branch orthologs are not conserved: as well as evidence of poor interactions between the WiSho1 Src-homology 3 (SH3) domain and the WiPbs2 proline-rich motif, the absence of a considerable part of the osmosensing apparatus in the genome of W. ichthyophaga suggests that the SHO1 branch components are not involved in HOG signaling in this halophilic fungus. In contrast, the conserved activation of WiPbs2 by the S. cerevisiae ScSsk2/ScSsk22 kinase and the sensitivity of W. ichthyophaga cells to fludioxonil, emphasize the significance of two-component (SLN1-like) signaling via Group III histidine kinase. Combined with the protein modeling data, our study reveals conserved and nonconserved protein interactions in the HOG signaling pathway of W. ichthyophaga and therefore significantly improves the knowledge of hyperosmotic signal processing in this halophilic fungus.
Cooperation of local motions in the Hsp90 molecular chaperone ATPase mechanism Schulze, Andrea; Beliu, Gerti; Helmerich, Dominic A; Schubert, Jonathan; Pearl, Laurence H; Prodromou, Chrisostomos; Neuweiler, Hannes in Nat Chem Biol (2016). advance online publication
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The Hsp90 chaperone is a central node of protein homeostasis, activating many diverse client proteins. Hsp90 functions as a molecular clamp that closes and opens in response to the binding and hydrolysis of ATP. Crystallographic studies have defined distinct conformational states of the mechanistic core, implying structural changes that have not yet been observed in solution. Here we engineered one-nanometer fluorescence probes based on photoinduced electron transfer into the yeast Hsp90 to observe these motions. We found that the ATPase activity of the chaperone was reflected in the kinetics of specific structural rearrangements at remote positions that acted cooperatively. Nanosecond single-molecule fluorescence fluctuation analysis uncovered that critical structural elements that undergo rearrangement were mobile on a sub-millisecond time scale. We identified a two-step mechanism for lid closure over the nucleotide-binding pocket. The activating co-chaperone Aha1 mobilized the lid of apo Hsp90, suggesting an early role in the catalytic cycle.

@article{schulze2016cooperation, abstract = {The Hsp90 chaperone is a central node of protein homeostasis, activating many diverse client proteins. Hsp90 functions as a molecular clamp that closes and opens in response to the binding and hydrolysis of ATP. Crystallographic studies have defined distinct conformational states of the mechanistic core, implying structural changes that have not yet been observed in solution. Here we engineered one-nanometer fluorescence probes based on photoinduced electron transfer into the yeast Hsp90 to observe these motions. We found that the ATPase activity of the chaperone was reflected in the kinetics of specific structural rearrangements at remote positions that acted cooperatively. Nanosecond single-molecule fluorescence fluctuation analysis uncovered that critical structural elements that undergo rearrangement were mobile on a sub-millisecond time scale. We identified a two-step mechanism for lid closure over the nucleotide-binding pocket. The activating co-chaperone Aha1 mobilized the lid of apo Hsp90, suggesting an early role in the catalytic cycle.}, author = {Schulze, Andrea and Beliu, Gerti and Helmerich, Dominic A and Schubert, Jonathan and Pearl, Laurence H and Prodromou, Chrisostomos and Neuweiler, Hannes}, journal = {Nat Chem Biol}, keywords = {hannes}, month = {jun}, publisher = {Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.}, title = {Cooperation of local motions in the Hsp90 molecular chaperone ATPase mechanism}, volume = {advance online publication}, year = 2016 }

%0 Journal Article %1 schulze2016cooperation %A Schulze, Andrea %A Beliu, Gerti %A Helmerich, Dominic A %A Schubert, Jonathan %A Pearl, Laurence H %A Prodromou, Chrisostomos %A Neuweiler, Hannes %D 2016 %I Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved. %J Nat Chem Biol %T Cooperation of local motions in the Hsp90 molecular chaperone ATPase mechanism %U http://dx.doi.org/10.1038/nchembio.2111 %V advance online publication %X The Hsp90 chaperone is a central node of protein homeostasis, activating many diverse client proteins. Hsp90 functions as a molecular clamp that closes and opens in response to the binding and hydrolysis of ATP. Crystallographic studies have defined distinct conformational states of the mechanistic core, implying structural changes that have not yet been observed in solution. Here we engineered one-nanometer fluorescence probes based on photoinduced electron transfer into the yeast Hsp90 to observe these motions. We found that the ATPase activity of the chaperone was reflected in the kinetics of specific structural rearrangements at remote positions that acted cooperatively. Nanosecond single-molecule fluorescence fluctuation analysis uncovered that critical structural elements that undergo rearrangement were mobile on a sub-millisecond time scale. We identified a two-step mechanism for lid closure over the nucleotide-binding pocket. The activating co-chaperone Aha1 mobilized the lid of apo Hsp90, suggesting an early role in the catalytic cycle.
Neurofilament depletion improves microtubule dynamics via modulation of Stat3/stathmin signaling Yadav, Preeti; Selvaraj, Bhuvaneish T.; Bender, Florian L. P.; Behringer, Marcus; Moradi, Mehri; Sivadasan, Rajeeve; Dombert, Benjamin; Blum, Robert; Asan, Esther; Sauer, Markus; Julien, Jean-Pierre; Sendtner, Michael in Acta Neuropathologica (2016). 132(1) 93–110.
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In neurons, microtubules form a dense array within axons, and the stability and function of this microtubule network is modulated by neurofilaments. Accumulation of neurofilaments has been observed in several forms of neurodegenerative diseases, but the mechanisms how elevated neurofilament levels destabilize axons are unknown so far. Here, we show that increased neurofilament expression in motor nerves of pmn mutant mice, a model of motoneuron disease, causes disturbed microtubule dynamics. The disease is caused by a point mutation in the tubulin-specific chaperone E (Tbce) gene, leading to an exchange of the most C-terminal amino acid tryptophan to glycine. As a consequence, the TBCE protein becomes instable which then results in destabilization of axonal microtubules and defects in axonal transport, in particular in motoneurons. Depletion of neurofilament increases the number and regrowth of microtubules in pmn mutant motoneurons and restores axon elongation. This effect is mediated by interaction of neurofilament with the stathmin complex. Accumulating neurofilaments associate with stathmin in axons of pmn mutant motoneurons. Depletion of neurofilament by Nefl knockout increases Stat3–stathmin interaction and stabilizes the microtubules in pmn mutant motoneurons. Consequently, counteracting enhanced neurofilament expression improves axonal maintenance and prolongs survival of pmn mutant mice. We propose that this mechanism could also be relevant for other neurodegenerative diseases in which neurofilament accumulation and loss of microtubules are prominent features.

@article{yadav2016neurofilament, abstract = {In neurons, microtubules form a dense array within axons, and the stability and function of this microtubule network is modulated by neurofilaments. Accumulation of neurofilaments has been observed in several forms of neurodegenerative diseases, but the mechanisms how elevated neurofilament levels destabilize axons are unknown so far. Here, we show that increased neurofilament expression in motor nerves of pmn mutant mice, a model of motoneuron disease, causes disturbed microtubule dynamics. The disease is caused by a point mutation in the tubulin-specific chaperone E (Tbce) gene, leading to an exchange of the most C-terminal amino acid tryptophan to glycine. As a consequence, the TBCE protein becomes instable which then results in destabilization of axonal microtubules and defects in axonal transport, in particular in motoneurons. Depletion of neurofilament increases the number and regrowth of microtubules in pmn mutant motoneurons and restores axon elongation. This effect is mediated by interaction of neurofilament with the stathmin complex. Accumulating neurofilaments associate with stathmin in axons of pmn mutant motoneurons. Depletion of neurofilament by Nefl knockout increases Stat3–stathmin interaction and stabilizes the microtubules in pmn mutant motoneurons. Consequently, counteracting enhanced neurofilament expression improves axonal maintenance and prolongs survival of pmn mutant mice. We propose that this mechanism could also be relevant for other neurodegenerative diseases in which neurofilament accumulation and loss of microtubules are prominent features.}, author = {Yadav, Preeti and Selvaraj, Bhuvaneish T. and Bender, Florian L. P. and Behringer, Marcus and Moradi, Mehri and Sivadasan, Rajeeve and Dombert, Benjamin and Blum, Robert and Asan, Esther and Sauer, Markus and Julien, Jean-Pierre and Sendtner, Michael}, journal = {Acta Neuropathologica}, keywords = {sauer}, number = 1, pages = {93–110}, title = {Neurofilament depletion improves microtubule dynamics via modulation of Stat3/stathmin signaling}, volume = 132, year = 2016 }

%0 Journal Article %1 yadav2016neurofilament %A Yadav, Preeti %A Selvaraj, Bhuvaneish T. %A Bender, Florian L. P. %A Behringer, Marcus %A Moradi, Mehri %A Sivadasan, Rajeeve %A Dombert, Benjamin %A Blum, Robert %A Asan, Esther %A Sauer, Markus %A Julien, Jean-Pierre %A Sendtner, Michael %D 2016 %J Acta Neuropathologica %N 1 %P 93--110 %R 10.1007/s00401-016-1564-y %T Neurofilament depletion improves microtubule dynamics via modulation of Stat3/stathmin signaling %U http://dx.doi.org/10.1007/s00401-016-1564-y %V 132 %X In neurons, microtubules form a dense array within axons, and the stability and function of this microtubule network is modulated by neurofilaments. Accumulation of neurofilaments has been observed in several forms of neurodegenerative diseases, but the mechanisms how elevated neurofilament levels destabilize axons are unknown so far. Here, we show that increased neurofilament expression in motor nerves of pmn mutant mice, a model of motoneuron disease, causes disturbed microtubule dynamics. The disease is caused by a point mutation in the tubulin-specific chaperone E (Tbce) gene, leading to an exchange of the most C-terminal amino acid tryptophan to glycine. As a consequence, the TBCE protein becomes instable which then results in destabilization of axonal microtubules and defects in axonal transport, in particular in motoneurons. Depletion of neurofilament increases the number and regrowth of microtubules in pmn mutant motoneurons and restores axon elongation. This effect is mediated by interaction of neurofilament with the stathmin complex. Accumulating neurofilaments associate with stathmin in axons of pmn mutant motoneurons. Depletion of neurofilament by Nefl knockout increases Stat3–stathmin interaction and stabilizes the microtubules in pmn mutant motoneurons. Consequently, counteracting enhanced neurofilament expression improves axonal maintenance and prolongs survival of pmn mutant mice. We propose that this mechanism could also be relevant for other neurodegenerative diseases in which neurofilament accumulation and loss of microtubules are prominent features.
The CsrA-FliW network controls polar localization of the dual-function flagellin mRNA in Campylobacter jejuni Dugar, Gaurav; Svensson, Sarah L.; Bischler, Thorsten; Wäldchen, Sina; Reinhardt, Richard; Sauer, Markus; Sharma, Cynthia M. in Nature Communications (2016). 7 11667-.
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The widespread CsrA/RsmA protein regulators repress translation by binding GGA motifs in bacterial mRNAs. CsrA activity is primarily controlled through sequestration by multiple small regulatory RNAs. Here we investigate CsrA activity control in the absence of antagonizing small RNAs by examining the CsrA regulon in the human pathogen Campylobacter jejuni. We use genome-wide co-immunoprecipitation combined with RNA sequencing to show that CsrA primarily binds flagellar mRNAs and identify the major flagellin mRNA (flaA) as the main CsrA target. The flaA mRNA is translationally repressed by CsrA, but it can also titrate CsrA activity. Together with the main C. jejuni CsrA antagonist, the FliW protein, flaA mRNA controls CsrA-mediated post-transcriptional regulation of other flagellar genes. RNA-FISH reveals that flaA mRNA is expressed and localized at the poles of elongating cells. Polar flaA mRNA localization is translation dependent and is post-transcriptionally regulated by the CsrA-FliW network. Overall, our results suggest a role for CsrA-FliW in spatiotemporal control of flagella assembly and localization of a dual-function mRNA.

@article{dugar2016csrafliw, abstract = {The widespread CsrA/RsmA protein regulators repress translation by binding GGA motifs in bacterial mRNAs. CsrA activity is primarily controlled through sequestration by multiple small regulatory RNAs. Here we investigate CsrA activity control in the absence of antagonizing small RNAs by examining the CsrA regulon in the human pathogen Campylobacter jejuni. We use genome-wide co-immunoprecipitation combined with RNA sequencing to show that CsrA primarily binds flagellar mRNAs and identify the major flagellin mRNA (flaA) as the main CsrA target. The flaA mRNA is translationally repressed by CsrA, but it can also titrate CsrA activity. Together with the main C. jejuni CsrA antagonist, the FliW protein, flaA mRNA controls CsrA-mediated post-transcriptional regulation of other flagellar genes. RNA-FISH reveals that flaA mRNA is expressed and localized at the poles of elongating cells. Polar flaA mRNA localization is translation dependent and is post-transcriptionally regulated by the CsrA-FliW network. Overall, our results suggest a role for CsrA-FliW in spatiotemporal control of flagella assembly and localization of a dual-function mRNA.}, author = {Dugar, Gaurav and Svensson, Sarah L. and Bischler, Thorsten and Wäldchen, Sina and Reinhardt, Richard and Sauer, Markus and Sharma, Cynthia M.}, journal = {Nature Communications}, keywords = {sauer}, month = {may}, pages = {11667–}, publisher = {The Author(s)}, title = {The CsrA-FliW network controls polar localization of the dual-function flagellin mRNA in Campylobacter jejuni}, volume = 7, year = 2016 }

%0 Journal Article %1 dugar2016csrafliw %A Dugar, Gaurav %A Svensson, Sarah L. %A Bischler, Thorsten %A Wäldchen, Sina %A Reinhardt, Richard %A Sauer, Markus %A Sharma, Cynthia M. %D 2016 %I The Author(s) %J Nature Communications %P 11667-- %T The CsrA-FliW network controls polar localization of the dual-function flagellin mRNA in Campylobacter jejuni %U http://dx.doi.org/10.1038/ncomms11667 %V 7 %X The widespread CsrA/RsmA protein regulators repress translation by binding GGA motifs in bacterial mRNAs. CsrA activity is primarily controlled through sequestration by multiple small regulatory RNAs. Here we investigate CsrA activity control in the absence of antagonizing small RNAs by examining the CsrA regulon in the human pathogen Campylobacter jejuni. We use genome-wide co-immunoprecipitation combined with RNA sequencing to show that CsrA primarily binds flagellar mRNAs and identify the major flagellin mRNA (flaA) as the main CsrA target. The flaA mRNA is translationally repressed by CsrA, but it can also titrate CsrA activity. Together with the main C. jejuni CsrA antagonist, the FliW protein, flaA mRNA controls CsrA-mediated post-transcriptional regulation of other flagellar genes. RNA-FISH reveals that flaA mRNA is expressed and localized at the poles of elongating cells. Polar flaA mRNA localization is translation dependent and is post-transcriptionally regulated by the CsrA-FliW network. Overall, our results suggest a role for CsrA-FliW in spatiotemporal control of flagella assembly and localization of a dual-function mRNA.
Filling the gap: adding super-resolution to array tomography for correlated ultrastructural and molecular identification of electrical synapses at the C. elegans connectome Markert, Sebastian Matthias; Britz, Sebastian; Proppert, Sven; Lang, Marietta; Witvliet, Daniel; Mulcahy, Ben; Sauer, Markus; Zhen, Mei; Bessereau, Jean-Louis; Stigloher, Christian in Neurophotonics (2016). 3(4) 041802–041802.
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Correlating molecular labeling at the ultrastructural level with high confidence remains challenging. Array tomography (AT) allows for a combination of fluorescence and electron microscopy (EM) to visualize subcellular protein localization on serial EM sections. Here, we describe an application for AT that combines near-native tissue preservation via high-pressure freezing and freeze substitution with super-resolution light microscopy and high-resolution scanning electron microscopy (SEM) analysis on the same section. We established protocols that combine SEM with structured illumination microscopy (SIM) and direct stochastic optical reconstruction microscopy (dSTORM). We devised a method for easy, precise, and unbiased correlation of EM images and super-resolution imaging data using endogenous cellular landmarks and freely available image processing software. We demonstrate that these methods allow us to identify and label gap junctions in Caenorhabditis elegans with precision and confidence, and imaging of even smaller structures is feasible. With the emergence of connectomics, these methods will allow us to fill in the gap—acquiring the correlated ultrastructural and molecular identity of electrical synapses.

@article{markert2016filling, abstract = {Correlating molecular labeling at the ultrastructural level with high confidence remains challenging. Array tomography (AT) allows for a combination of fluorescence and electron microscopy (EM) to visualize subcellular protein localization on serial EM sections. Here, we describe an application for AT that combines near-native tissue preservation via high-pressure freezing and freeze substitution with super-resolution light microscopy and high-resolution scanning electron microscopy (SEM) analysis on the same section. We established protocols that combine SEM with structured illumination microscopy (SIM) and direct stochastic optical reconstruction microscopy (dSTORM). We devised a method for easy, precise, and unbiased correlation of EM images and super-resolution imaging data using endogenous cellular landmarks and freely available image processing software. We demonstrate that these methods allow us to identify and label gap junctions in Caenorhabditis elegans with precision and confidence, and imaging of even smaller structures is feasible. With the emergence of connectomics, these methods will allow us to fill in the gap—acquiring the correlated ultrastructural and molecular identity of electrical synapses.}, author = {Markert, Sebastian Matthias and Britz, Sebastian and Proppert, Sven and Lang, Marietta and Witvliet, Daniel and Mulcahy, Ben and Sauer, Markus and Zhen, Mei and Bessereau, Jean-Louis and Stigloher, Christian}, journal = {Neurophotonics}, keywords = {sauer}, number = 4, pages = {041802–041802}, title = {Filling the gap: adding super-resolution to array tomography for correlated ultrastructural and molecular identification of electrical synapses at the C. elegans connectome}, volume = 3, year = 2016 }

%0 Journal Article %1 markert2016filling %A Markert, Sebastian Matthias %A Britz, Sebastian %A Proppert, Sven %A Lang, Marietta %A Witvliet, Daniel %A Mulcahy, Ben %A Sauer, Markus %A Zhen, Mei %A Bessereau, Jean-Louis %A Stigloher, Christian %D 2016 %J Neurophotonics %N 4 %P 041802--041802 %T Filling the gap: adding super-resolution to array tomography for correlated ultrastructural and molecular identification of electrical synapses at the C. elegans connectome %U http://dx.doi.org/10.1117/1.NPh.3.4.041802 %V 3 %X Correlating molecular labeling at the ultrastructural level with high confidence remains challenging. Array tomography (AT) allows for a combination of fluorescence and electron microscopy (EM) to visualize subcellular protein localization on serial EM sections. Here, we describe an application for AT that combines near-native tissue preservation via high-pressure freezing and freeze substitution with super-resolution light microscopy and high-resolution scanning electron microscopy (SEM) analysis on the same section. We established protocols that combine SEM with structured illumination microscopy (SIM) and direct stochastic optical reconstruction microscopy (dSTORM). We devised a method for easy, precise, and unbiased correlation of EM images and super-resolution imaging data using endogenous cellular landmarks and freely available image processing software. We demonstrate that these methods allow us to identify and label gap junctions in Caenorhabditis elegans with precision and confidence, and imaging of even smaller structures is feasible. With the emergence of connectomics, these methods will allow us to fill in the gap—acquiring the correlated ultrastructural and molecular identity of electrical synapses.
Super-resolution imaging of plasma membrane proteins with click chemistry Mateos-Gil, Pablo; Letschert, Sebastian; Doose, Soeren; Sauer, Markus in Frontiers in Cell and Developmental Biology (2016). 4 98-.
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Besides its function as a passive cell wall, the plasma membrane (PM) serves as a platform for different physiological processes such as signal transduction and cell adhesion, determining the ability of cells to communicate with the exterior and form tissues. Therefore, the spatial distribution of PM components, and the molecular mechanisms underlying it, have important implications in various biological fields including cell development, neurobiology, and immunology. The existence of confined compartments in the plasma membrane that vary on many length scales from protein multimers to micrometer-size domains with different protein and lipid composition is today beyond all questions. As much as the physiology of cells is controlled by the spatial organization of PM components, the study of distribution, size and composition remains challenging. Visualization of the molecular distribution of PM components has been impeded mainly due to two problems: the specific labeling of lipids and proteins without perturbing their native distribution and the diffraction-limit of fluorescence microscopy restricting the resolution to about half the wavelength of light. Here, we present a bioorthogonal chemical reporter strategy based on click chemistry and metabolic labeling for efficient and specific visualization of PM proteins and glycans with organic fluorophores in combination with super-resolution fluorescence imaging by direct stochastic optical reconstruction microscopy (dSTORM) with single-molecule sensitivity.

@article{mateosgil2016superresolution, abstract = {Besides its function as a passive cell wall, the plasma membrane (PM) serves as a platform for different physiological processes such as signal transduction and cell adhesion, determining the ability of cells to communicate with the exterior and form tissues. Therefore, the spatial distribution of PM components, and the molecular mechanisms underlying it, have important implications in various biological fields including cell development, neurobiology, and immunology. The existence of confined compartments in the plasma membrane that vary on many length scales from protein multimers to micrometer-size domains with different protein and lipid composition is today beyond all questions. As much as the physiology of cells is controlled by the spatial organization of PM components, the study of distribution, size and composition remains challenging. Visualization of the molecular distribution of PM components has been impeded mainly due to two problems: the specific labeling of lipids and proteins without perturbing their native distribution and the diffraction-limit of fluorescence microscopy restricting the resolution to about half the wavelength of light. Here, we present a bioorthogonal chemical reporter strategy based on click chemistry and metabolic labeling for efficient and specific visualization of PM proteins and glycans with organic fluorophores in combination with super-resolution fluorescence imaging by direct stochastic optical reconstruction microscopy (dSTORM) with single-molecule sensitivity.}, author = {Mateos-Gil, Pablo and Letschert, Sebastian and Doose, Soeren and Sauer, Markus}, journal = {Frontiers in Cell and Developmental Biology}, keywords = {sauer}, pages = {98–}, title = {Super-resolution imaging of plasma membrane proteins with click chemistry}, volume = 4, year = 2016 }

%0 Journal Article %1 mateosgil2016superresolution %A Mateos-Gil, Pablo %A Letschert, Sebastian %A Doose, Soeren %A Sauer, Markus %D 2016 %J Frontiers in Cell and Developmental Biology %P 98-- %T Super-resolution imaging of plasma membrane proteins with click chemistry %U http://journal.frontiersin.org/article/10.3389/fcell.2016.00098 %V 4 %X Besides its function as a passive cell wall, the plasma membrane (PM) serves as a platform for different physiological processes such as signal transduction and cell adhesion, determining the ability of cells to communicate with the exterior and form tissues. Therefore, the spatial distribution of PM components, and the molecular mechanisms underlying it, have important implications in various biological fields including cell development, neurobiology, and immunology. The existence of confined compartments in the plasma membrane that vary on many length scales from protein multimers to micrometer-size domains with different protein and lipid composition is today beyond all questions. As much as the physiology of cells is controlled by the spatial organization of PM components, the study of distribution, size and composition remains challenging. Visualization of the molecular distribution of PM components has been impeded mainly due to two problems: the specific labeling of lipids and proteins without perturbing their native distribution and the diffraction-limit of fluorescence microscopy restricting the resolution to about half the wavelength of light. Here, we present a bioorthogonal chemical reporter strategy based on click chemistry and metabolic labeling for efficient and specific visualization of PM proteins and glycans with organic fluorophores in combination with super-resolution fluorescence imaging by direct stochastic optical reconstruction microscopy (dSTORM) with single-molecule sensitivity.
Optochemokine Tandem for Light-Control of Intracellular Ca²⁺ Feldbauer, Katrin; Schlegel, Jan; Weissbecker, Juliane; Sauer, Frank; Wood, Phillip G.; Bamberg, Ernst; Terpitz, Ulrich in PLoS ONE (2016). 11(10) e0165344-.
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An optochemokine tandem was developed to control the release of calcium from endosomes into the cytosol by light and to analyze the internalization kinetics of G-protein coupled receptors (GPCRs) by electrophysiology. A previously constructed rhodopsin tandem was re-engineered to combine the light-gated Ca2+-permeable cation channel Channelrhodopsin-2(L132C), CatCh, with the chemokine receptor CXCR4 in a functional tandem protein tCXCR4/CatCh. The GPCR was used as a shuttle protein to displace CatCh from the plasma membrane into intracellular areas. As shown by patch-clamp measurements and confocal laser scanning microscopy, heterologously expressed tCXCR4/CatCh was internalized via the endocytic SDF1/CXCR4 signaling pathway. The kinetics of internalization could be followed electrophysiologically via the amplitude of the CatCh signal. The light-induced release of Ca2+ by tandem endosomes into the cytosol via CatCh was visualized using the Ca2+-sensitive dyes rhod2 and rhod2-AM showing an increase of intracellular Ca2+ in response to light.

@article{feldbauer2016optochemokine, abstract = {An optochemokine tandem was developed to control the release of calcium from endosomes into the cytosol by light and to analyze the internalization kinetics of G-protein coupled receptors (GPCRs) by electrophysiology. A previously constructed rhodopsin tandem was re-engineered to combine the light-gated Ca2+-permeable cation channel Channelrhodopsin-2(L132C), CatCh, with the chemokine receptor CXCR4 in a functional tandem protein tCXCR4/CatCh. The GPCR was used as a shuttle protein to displace CatCh from the plasma membrane into intracellular areas. As shown by patch-clamp measurements and confocal laser scanning microscopy, heterologously expressed tCXCR4/CatCh was internalized via the endocytic SDF1/CXCR4 signaling pathway. The kinetics of internalization could be followed electrophysiologically via the amplitude of the CatCh signal. The light-induced release of Ca2+ by tandem endosomes into the cytosol via CatCh was visualized using the Ca2+-sensitive dyes rhod2 and rhod2-AM showing an increase of intracellular Ca2+ in response to light.}, author = {Feldbauer, Katrin and Schlegel, Jan and Weissbecker, Juliane and Sauer, Frank and Wood, Phillip G. and Bamberg, Ernst and Terpitz, Ulrich}, journal = {PLoS ONE}, keywords = {terpitz}, month = {oct}, number = 10, pages = {e0165344–}, publisher = {Public Library of Science}, title = {Optochemokine Tandem for Light-Control of Intracellular Ca2+}, volume = 11, year = 2016 }

%0 Journal Article %1 feldbauer2016optochemokine %A Feldbauer, Katrin %A Schlegel, Jan %A Weissbecker, Juliane %A Sauer, Frank %A Wood, Phillip G. %A Bamberg, Ernst %A Terpitz, Ulrich %D 2016 %I Public Library of Science %J PLoS ONE %N 10 %P e0165344-- %T Optochemokine Tandem for Light-Control of Intracellular Ca2+ %U http://dx.doi.org/10.1371/journal.pone.0165344 %V 11 %X An optochemokine tandem was developed to control the release of calcium from endosomes into the cytosol by light and to analyze the internalization kinetics of G-protein coupled receptors (GPCRs) by electrophysiology. A previously constructed rhodopsin tandem was re-engineered to combine the light-gated Ca2+-permeable cation channel Channelrhodopsin-2(L132C), CatCh, with the chemokine receptor CXCR4 in a functional tandem protein tCXCR4/CatCh. The GPCR was used as a shuttle protein to displace CatCh from the plasma membrane into intracellular areas. As shown by patch-clamp measurements and confocal laser scanning microscopy, heterologously expressed tCXCR4/CatCh was internalized via the endocytic SDF1/CXCR4 signaling pathway. The kinetics of internalization could be followed electrophysiologically via the amplitude of the CatCh signal. The light-induced release of Ca2+ by tandem endosomes into the cytosol via CatCh was visualized using the Ca2+-sensitive dyes rhod2 and rhod2-AM showing an increase of intracellular Ca2+ in response to light.
A Functionalized Sphingolipid Analogue for Studying Redistribution during Activation in Living T Cells Collenburg, Lena; Walter, Tim; Burgert, Anne; Müller, Nora; Seibel, Jürgen; Japtok, Lukasz; Kleuser, Burkhard; Sauer, Markus; Schneider-Schaulies, Sibylle in The Journal of Immunology (2016). 196(9) 3951–3962.
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Sphingolipids are major components of the plasma membrane. In particular, ceramide serves as an essential building hub for complex sphingolipids, but also as an organizer of membrane domains segregating receptors and signalosomes. Sphingomyelin breakdown as a result of sphingomyelinase activation after ligation of a variety of receptors is the predominant source of ceramides released at the plasma membrane. This especially applies to T lymphocytes where formation of ceramide-enriched membrane microdomains modulates TCR signaling. Because ceramide release and redistribution occur very rapidly in response to receptor ligation, novel tools to further study these processes in living T cells are urgently needed. To meet this demand, we synthesized nontoxic, azido-functionalized ceramides allowing for bio-orthogonal click-reactions to fluorescently label incorporated ceramides, and thus investigate formation of ceramide-enriched domains. Azido-functionalized C6-ceramides were incorporated into and localized within plasma membrane microdomains and proximal vesicles in T cells. They segregated into clusters after TCR, and especially CD28 ligation, indicating efficient sorting into plasma membrane domains associated with T cell activation; this was abolished upon sphingomyelinase inhibition. Importantly, T cell activation was not abrogated upon incorporation of the compound, which was efficiently excluded from the immune synapse center as has previously been seen in Ab-based studies using fixed cells. Therefore, the functionalized ceramides are novel, highly potent tools to study the subcellular redistribution of ceramides in the course of T cell activation. Moreover, they will certainly also be generally applicable to studies addressing rapid stimulation-mediated ceramide release in living cells.

@article{collenburg2016functionalized, abstract = {Sphingolipids are major components of the plasma membrane. In particular, ceramide serves as an essential building hub for complex sphingolipids, but also as an organizer of membrane domains segregating receptors and signalosomes. Sphingomyelin breakdown as a result of sphingomyelinase activation after ligation of a variety of receptors is the predominant source of ceramides released at the plasma membrane. This especially applies to T lymphocytes where formation of ceramide-enriched membrane microdomains modulates TCR signaling. Because ceramide release and redistribution occur very rapidly in response to receptor ligation, novel tools to further study these processes in living T cells are urgently needed. To meet this demand, we synthesized nontoxic, azido-functionalized ceramides allowing for bio-orthogonal click-reactions to fluorescently label incorporated ceramides, and thus investigate formation of ceramide-enriched domains. Azido-functionalized C6-ceramides were incorporated into and localized within plasma membrane microdomains and proximal vesicles in T cells. They segregated into clusters after TCR, and especially CD28 ligation, indicating efficient sorting into plasma membrane domains associated with T cell activation; this was abolished upon sphingomyelinase inhibition. Importantly, T cell activation was not abrogated upon incorporation of the compound, which was efficiently excluded from the immune synapse center as has previously been seen in Ab-based studies using fixed cells. Therefore, the functionalized ceramides are novel, highly potent tools to study the subcellular redistribution of ceramides in the course of T cell activation. Moreover, they will certainly also be generally applicable to studies addressing rapid stimulation-mediated ceramide release in living cells.}, author = {Collenburg, Lena and Walter, Tim and Burgert, Anne and Müller, Nora and Seibel, Jürgen and Japtok, Lukasz and Kleuser, Burkhard and Sauer, Markus and Schneider-Schaulies, Sibylle}, journal = {The Journal of Immunology}, keywords = {sauer}, month = {may}, number = 9, pages = {3951–3962}, title = {A Functionalized Sphingolipid Analogue for Studying Redistribution during Activation in Living T Cells}, volume = 196, year = 2016 }

%0 Journal Article %1 collenburg2016functionalized %A Collenburg, Lena %A Walter, Tim %A Burgert, Anne %A Müller, Nora %A Seibel, Jürgen %A Japtok, Lukasz %A Kleuser, Burkhard %A Sauer, Markus %A Schneider-Schaulies, Sibylle %D 2016 %J The Journal of Immunology %N 9 %P 3951--3962 %T A Functionalized Sphingolipid Analogue for Studying Redistribution during Activation in Living T Cells %U http://www.jimmunol.org/content/196/9/3951.abstract %V 196 %X Sphingolipids are major components of the plasma membrane. In particular, ceramide serves as an essential building hub for complex sphingolipids, but also as an organizer of membrane domains segregating receptors and signalosomes. Sphingomyelin breakdown as a result of sphingomyelinase activation after ligation of a variety of receptors is the predominant source of ceramides released at the plasma membrane. This especially applies to T lymphocytes where formation of ceramide-enriched membrane microdomains modulates TCR signaling. Because ceramide release and redistribution occur very rapidly in response to receptor ligation, novel tools to further study these processes in living T cells are urgently needed. To meet this demand, we synthesized nontoxic, azido-functionalized ceramides allowing for bio-orthogonal click-reactions to fluorescently label incorporated ceramides, and thus investigate formation of ceramide-enriched domains. Azido-functionalized C6-ceramides were incorporated into and localized within plasma membrane microdomains and proximal vesicles in T cells. They segregated into clusters after TCR, and especially CD28 ligation, indicating efficient sorting into plasma membrane domains associated with T cell activation; this was abolished upon sphingomyelinase inhibition. Importantly, T cell activation was not abrogated upon incorporation of the compound, which was efficiently excluded from the immune synapse center as has previously been seen in Ab-based studies using fixed cells. Therefore, the functionalized ceramides are novel, highly potent tools to study the subcellular redistribution of ceramides in the course of T cell activation. Moreover, they will certainly also be generally applicable to studies addressing rapid stimulation-mediated ceramide release in living cells.
Synthesis and application of water-soluble, photoswitchable cyanine dyes for bioorthogonal labeling of cell-surface carbohydrates Alexander, Mertsch; Sebastian, Letschert; Elisabeth, Memmel; Markus, Sauer; Jürgen, Seibel (2016). 347-.
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The synthesis of cyanine dyes addressing absorption wavelengths at 550 and 648 nm is reported. Alkyne functionalized dyes were used for bioorthogonal click reactions by labeling of metabolically incorporated sugar-azides on the surface of living neuroblastoma cells, which were applied to direct stochastic optical reconstruction microscopy (dSTORM) for the visualization of cell-surface glycans in the nm-range.

@misc{alexander2016synthesis, abstract = {The synthesis of cyanine dyes addressing absorption wavelengths at 550 and 648 nm is reported. Alkyne functionalized dyes were used for bioorthogonal click reactions by labeling of metabolically incorporated sugar-azides on the surface of living neuroblastoma cells, which were applied to direct stochastic optical reconstruction microscopy (dSTORM) for the visualization of cell-surface glycans in the nm-range.}, author = {Alexander, Mertsch and Sebastian, Letschert and Elisabeth, Memmel and Markus, Sauer and Jürgen, Seibel}, booktitle = {Zeitschrift für Naturforschung C}, keywords = {sauer}, pages = {347–}, title = {Synthesis and application of water-soluble, photoswitchable cyanine dyes for bioorthogonal labeling of cell-surface carbohydrates}, volume = 71, year = 2016 }

%0 Generic %1 alexander2016synthesis %A Alexander, Mertsch %A Sebastian, Letschert %A Elisabeth, Memmel %A Markus, Sauer %A Jürgen, Seibel %B Zeitschrift für Naturforschung C %D 2016 %P 347-- %R 10.1515/znc-2016-0123 %T Synthesis and application of water-soluble, photoswitchable cyanine dyes for bioorthogonal labeling of cell-surface carbohydrates %U https://www.degruyter.com/view/j/znc.2016.71.issue-9-10/znc-2016-0123/znc-2016-0123.xml %V 71 %X The synthesis of cyanine dyes addressing absorption wavelengths at 550 and 648 nm is reported. Alkyne functionalized dyes were used for bioorthogonal click reactions by labeling of metabolically incorporated sugar-azides on the surface of living neuroblastoma cells, which were applied to direct stochastic optical reconstruction microscopy (dSTORM) for the visualization of cell-surface glycans in the nm-range.
Precise Somatotopic Thalamocortical Axon Guidance Depends on LPA-Mediated PRG-2/Radixin Signaling Cheng, Jin; Sahani, Sadhna; Hausrat, Torben Johann; Yang, Jenq-Wei; Ji, Haichao; Schmarowski, Nikolai; Endle, Heiko; Liu, Xinfeng; Li, Yunbo; Böttche, Rahel; Radyushkin, Konstantin; Maric, Hans M; Hoerder-Suabedissen, Anna; Molnár, Zoltán; Prouvot, Pierre-Hugues; Trimbuch, Thorsten; Ninnemann, Olaf; Huai, Jisen; Fan, Wei; Visentin, Barbara; Sabbadini, Roger; Strømgaard, Kristian; Stroh, Albrecht; Luhmann, Heiko J; Kneussel, Matthias; Nitsch, Robert; Vogt, Johannes in Neuron (2016). 92(1) 126–142.
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Summary Precise connection of thalamic barreloids with their corresponding cortical barrels is critical for processing of vibrissal sensory information. Here, we show that PRG-2, a phospholipid-interacting molecule, is important for thalamocortical axon guidance. Developing thalamocortical fibers both in PRG-2 full knockout (KO) and in thalamus-specific KO mice prematurely entered the cortical plate, eventually innervating non-corresponding barrels. This misrouting relied on lost axonal sensitivity toward lysophosphatidic acid (LPA), which failed to repel PRG-2-deficient thalamocortical fibers. PRG-2 electroporation in the PRG-2−/− thalamus restored the aberrant cortical innervation. We identified radixin as a PRG-2 interaction partner and showed that radixin accumulation in growth cones and its LPA-dependent phosphorylation depend on its binding to specific regions within the C-terminal region of PRG-2. In vivo recordings and whisker-specific behavioral tests demonstrated sensory discrimination deficits in PRG-2−/− animals. Our data show that bioactive phospholipids and PRG-2 are critical for guiding thalamic axons to their proper cortical targets.

@article{cheng2016precise, abstract = {Summary Precise connection of thalamic barreloids with their corresponding cortical barrels is critical for processing of vibrissal sensory information. Here, we show that PRG-2, a phospholipid-interacting molecule, is important for thalamocortical axon guidance. Developing thalamocortical fibers both in PRG-2 full knockout (KO) and in thalamus-specific KO mice prematurely entered the cortical plate, eventually innervating non-corresponding barrels. This misrouting relied on lost axonal sensitivity toward lysophosphatidic acid (LPA), which failed to repel PRG-2-deficient thalamocortical fibers. PRG-2 electroporation in the PRG-2−/− thalamus restored the aberrant cortical innervation. We identified radixin as a PRG-2 interaction partner and showed that radixin accumulation in growth cones and its LPA-dependent phosphorylation depend on its binding to specific regions within the C-terminal region of PRG-2. In vivo recordings and whisker-specific behavioral tests demonstrated sensory discrimination deficits in PRG-2−/− animals. Our data show that bioactive phospholipids and PRG-2 are critical for guiding thalamic axons to their proper cortical targets.}, author = {Cheng, Jin and Sahani, Sadhna and Hausrat, Torben Johann and Yang, Jenq-Wei and Ji, Haichao and Schmarowski, Nikolai and Endle, Heiko and Liu, Xinfeng and Li, Yunbo and Böttche, Rahel and Radyushkin, Konstantin and Maric, Hans M and Hoerder-Suabedissen, Anna and Molnár, Zoltán and Prouvot, Pierre-Hugues and Trimbuch, Thorsten and Ninnemann, Olaf and Huai, Jisen and Fan, Wei and Visentin, Barbara and Sabbadini, Roger and Strømgaard, Kristian and Stroh, Albrecht and Luhmann, Heiko J and Kneussel, Matthias and Nitsch, Robert and Vogt, Johannes}, journal = {Neuron}, keywords = {maric}, number = 1, pages = {126–142}, title = {Precise Somatotopic Thalamocortical Axon Guidance Depends on LPA-Mediated PRG-2/Radixin Signaling}, volume = 92, year = 2016 }

%0 Journal Article %1 cheng2016precise %A Cheng, Jin %A Sahani, Sadhna %A Hausrat, Torben Johann %A Yang, Jenq-Wei %A Ji, Haichao %A Schmarowski, Nikolai %A Endle, Heiko %A Liu, Xinfeng %A Li, Yunbo %A Böttche, Rahel %A Radyushkin, Konstantin %A Maric, Hans M %A Hoerder-Suabedissen, Anna %A Molnár, Zoltán %A Prouvot, Pierre-Hugues %A Trimbuch, Thorsten %A Ninnemann, Olaf %A Huai, Jisen %A Fan, Wei %A Visentin, Barbara %A Sabbadini, Roger %A Strømgaard, Kristian %A Stroh, Albrecht %A Luhmann, Heiko J %A Kneussel, Matthias %A Nitsch, Robert %A Vogt, Johannes %D 2016 %J Neuron %N 1 %P 126--142 %R https://doi.org/10.1016/j.neuron.2016.08.035 %T Precise Somatotopic Thalamocortical Axon Guidance Depends on LPA-Mediated PRG-2/Radixin Signaling %U http://www.sciencedirect.com/science/article/pii/S0896627316305281 %V 92 %X Summary Precise connection of thalamic barreloids with their corresponding cortical barrels is critical for processing of vibrissal sensory information. Here, we show that PRG-2, a phospholipid-interacting molecule, is important for thalamocortical axon guidance. Developing thalamocortical fibers both in PRG-2 full knockout (KO) and in thalamus-specific KO mice prematurely entered the cortical plate, eventually innervating non-corresponding barrels. This misrouting relied on lost axonal sensitivity toward lysophosphatidic acid (LPA), which failed to repel PRG-2-deficient thalamocortical fibers. PRG-2 electroporation in the PRG-2−/− thalamus restored the aberrant cortical innervation. We identified radixin as a PRG-2 interaction partner and showed that radixin accumulation in growth cones and its LPA-dependent phosphorylation depend on its binding to specific regions within the C-terminal region of PRG-2. In vivo recordings and whisker-specific behavioral tests demonstrated sensory discrimination deficits in PRG-2−/− animals. Our data show that bioactive phospholipids and PRG-2 are critical for guiding thalamic axons to their proper cortical targets.
OmoMYC blunts promoter invasion by oncogenic MYC to inhibit gene expression characteristic of MYC-dependent tumors Jung, L A; Gebhardt, A; Koelmel, W; Ade, C P; Walz, S; Kuper, J; von Eyss, B; Letschert, S; Redel, C; d’Artista, L; Biankin, A; Zender, L; Sauer, M; Wolf, E; Evan, G; Kisker, C; Eilers, M in Oncogene (2016). 36 1911-.
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MYC genes have both essential roles during normal development and exert oncogenic functions during tumorigenesis. Expression of a dominant-negative allele of MYC, termed OmoMYC, can induce rapid tumor regression in mouse models with little toxicity for normal tissues. How OmoMYC discriminates between physiological and oncogenic functions of MYC is unclear. We have solved the crystal structure of OmoMYC and show that it forms a stable homodimer and as such recognizes DNA in the same manner as the MYC/MAX heterodimer. OmoMYC attenuates both MYC-dependent activation and repression by competing with MYC/MAX for binding to chromatin, effectively lowering MYC/MAX occupancy at its cognate binding sites. OmoMYC causes the largest decreases in promoter occupancy and changes in expression on genes that are invaded by oncogenic MYC levels. A signature of OmoMYC-regulated genes defines subgroups with high MYC levels in multiple tumor entities and identifies novel targets for the eradication of MYC-driven tumors.

@article{jung2016omomyc, abstract = {MYC genes have both essential roles during normal development and exert oncogenic functions during tumorigenesis. Expression of a dominant-negative allele of MYC, termed OmoMYC, can induce rapid tumor regression in mouse models with little toxicity for normal tissues. How OmoMYC discriminates between physiological and oncogenic functions of MYC is unclear. We have solved the crystal structure of OmoMYC and show that it forms a stable homodimer and as such recognizes DNA in the same manner as the MYC/MAX heterodimer. OmoMYC attenuates both MYC-dependent activation and repression by competing with MYC/MAX for binding to chromatin, effectively lowering MYC/MAX occupancy at its cognate binding sites. OmoMYC causes the largest decreases in promoter occupancy and changes in expression on genes that are invaded by oncogenic MYC levels. A signature of OmoMYC-regulated genes defines subgroups with high MYC levels in multiple tumor entities and identifies novel targets for the eradication of MYC-driven tumors.}, author = {Jung, L A and Gebhardt, A and Koelmel, W and Ade, C P and Walz, S and Kuper, J and von Eyss, B and Letschert, S and Redel, C and d'Artista, L and Biankin, A and Zender, L and Sauer, M and Wolf, E and Evan, G and Kisker, C and Eilers, M}, journal = {Oncogene}, keywords = {sauer}, month = {oct}, pages = {1911–}, publisher = {Macmillan Publishers Limited, part of Springer Nature.}, title = {OmoMYC blunts promoter invasion by oncogenic MYC to inhibit gene expression characteristic of MYC-dependent tumors}, volume = 36, year = 2016 }

%0 Journal Article %1 jung2016omomyc %A Jung, L A %A Gebhardt, A %A Koelmel, W %A Ade, C P %A Walz, S %A Kuper, J %A von Eyss, B %A Letschert, S %A Redel, C %A d'Artista, L %A Biankin, A %A Zender, L %A Sauer, M %A Wolf, E %A Evan, G %A Kisker, C %A Eilers, M %D 2016 %I Macmillan Publishers Limited, part of Springer Nature. %J Oncogene %P 1911-- %T OmoMYC blunts promoter invasion by oncogenic MYC to inhibit gene expression characteristic of MYC-dependent tumors %U http://dx.doi.org/10.1038/onc.2016.354 %V 36 %X MYC genes have both essential roles during normal development and exert oncogenic functions during tumorigenesis. Expression of a dominant-negative allele of MYC, termed OmoMYC, can induce rapid tumor regression in mouse models with little toxicity for normal tissues. How OmoMYC discriminates between physiological and oncogenic functions of MYC is unclear. We have solved the crystal structure of OmoMYC and show that it forms a stable homodimer and as such recognizes DNA in the same manner as the MYC/MAX heterodimer. OmoMYC attenuates both MYC-dependent activation and repression by competing with MYC/MAX for binding to chromatin, effectively lowering MYC/MAX occupancy at its cognate binding sites. OmoMYC causes the largest decreases in promoter occupancy and changes in expression on genes that are invaded by oncogenic MYC levels. A signature of OmoMYC-regulated genes defines subgroups with high MYC levels in multiple tumor entities and identifies novel targets for the eradication of MYC-driven tumors.
Gephyrin-binding peptides visualize postsynaptic sites and modulate neurotransmission Maric, Hans Michael; Hausrat, Torben Johann; Neubert, Franziska; Dalby, Nils Ole; Doose, Sören; Sauer, Markus; Kneussel, Matthias; Strømgaard, Kristian in Nature Chemical Biology (2016). 13 153-.
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γ-Aminobutyric acid type A and glycine receptors are the major mediators of fast synaptic inhibition in the human central nervous system and are established drug targets. However, all drugs targeting these receptors bind to the extracellular ligand-binding domain of the receptors, which inherently is associated with perturbation of the basic physiological action. Here we pursue a fundamentally different approach, by instead targeting the intracellular receptor–gephyrin interaction. First, we defined the gephyrin peptide-binding consensus sequence, which facilitated the development of gephyrin super-binding peptides and later effective affinity probes for the isolation of native gephyrin. Next, we demonstrated that fluorescent super-binding peptides could be used to directly visualize inhibitory postsynaptic sites for the first time in conventional and super-resolution microscopy. Finally, we demonstrate that the gephyrin super-binding peptides act as acute intracellular modulators of fast synaptic inhibition by modulating receptor clustering, thus being conceptually novel modulators of inhibitory neurotransmission.

@article{maric2016gephyrinbinding, abstract = {γ-Aminobutyric acid type A and glycine receptors are the major mediators of fast synaptic inhibition in the human central nervous system and are established drug targets. However, all drugs targeting these receptors bind to the extracellular ligand-binding domain of the receptors, which inherently is associated with perturbation of the basic physiological action. Here we pursue a fundamentally different approach, by instead targeting the intracellular receptor–gephyrin interaction. First, we defined the gephyrin peptide-binding consensus sequence, which facilitated the development of gephyrin super-binding peptides and later effective affinity probes for the isolation of native gephyrin. Next, we demonstrated that fluorescent super-binding peptides could be used to directly visualize inhibitory postsynaptic sites for the first time in conventional and super-resolution microscopy. Finally, we demonstrate that the gephyrin super-binding peptides act as acute intracellular modulators of fast synaptic inhibition by modulating receptor clustering, thus being conceptually novel modulators of inhibitory neurotransmission.}, author = {Maric, Hans Michael and Hausrat, Torben Johann and Neubert, Franziska and Dalby, Nils Ole and Doose, Sören and Sauer, Markus and Kneussel, Matthias and Strømgaard, Kristian}, journal = {Nature Chemical Biology}, keywords = {maric}, month = {nov}, pages = {153–}, publisher = {Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.}, title = {Gephyrin-binding peptides visualize postsynaptic sites and modulate neurotransmission}, volume = 13, year = 2016 }

%0 Journal Article %1 maric2016gephyrinbinding %A Maric, Hans Michael %A Hausrat, Torben Johann %A Neubert, Franziska %A Dalby, Nils Ole %A Doose, Sören %A Sauer, Markus %A Kneussel, Matthias %A Strømgaard, Kristian %D 2016 %I Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved. %J Nature Chemical Biology %P 153-- %T Gephyrin-binding peptides visualize postsynaptic sites and modulate neurotransmission %U https://doi.org/10.1038/nchembio.2246 %V 13 %X γ-Aminobutyric acid type A and glycine receptors are the major mediators of fast synaptic inhibition in the human central nervous system and are established drug targets. However, all drugs targeting these receptors bind to the extracellular ligand-binding domain of the receptors, which inherently is associated with perturbation of the basic physiological action. Here we pursue a fundamentally different approach, by instead targeting the intracellular receptor–gephyrin interaction. First, we defined the gephyrin peptide-binding consensus sequence, which facilitated the development of gephyrin super-binding peptides and later effective affinity probes for the isolation of native gephyrin. Next, we demonstrated that fluorescent super-binding peptides could be used to directly visualize inhibitory postsynaptic sites for the first time in conventional and super-resolution microscopy. Finally, we demonstrate that the gephyrin super-binding peptides act as acute intracellular modulators of fast synaptic inhibition by modulating receptor clustering, thus being conceptually novel modulators of inhibitory neurotransmission.
Human autoantibodies to amphiphysin induce defective presynaptic vesicle dynamics and composition Werner, Christian; Pauli, Martin; Doose, Sören; Weishaupt, Andreas; Haselmann, Holger; Grünewald, Benedikt; Sauer, Markus; Heckmann, Manfred; Toyka, Klaus V.; Asan, Esther; Sommer, Claudia; Geis, Christian in Brain (2016). 139(2) 365–379.
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See Irani (doi:10.1093/awv364) for a scientific commentary on this article. Stiff-person syndrome is the prototype of a central nervous system disorder with autoantibodies targeting presynaptic antigens. Patients with paraneoplastic stiff-person syndrome may harbour autoantibodies to the BAR (Bin/Amphiphysin/Rvs) domain protein amphiphysin, which target its SH3 domain. These patients have neurophysiological signs of compromised central inhibition and respond to symptomatic treatment with medication enhancing GABAergic transmission. High frequency neurotransmission as observed in tonic GABAergic interneurons relies on fast exocytosis of neurotransmitters based on compensatory endocytosis. As amphiphysin is involved in clathrin-mediated endocytosis, patient autoantibodies are supposed to interfere with this function, leading to disinhibition by reduction of GABAergic neurotransmission. We here investigated the effects of human anti-amphiphysin autoantibodies on structural components of presynaptic boutons ex vivo and in vitro using electron microscopy and super-resolution direct stochastic optical reconstruction microscopy. Ultrastructural analysis of spinal cord presynaptic boutons was performed after in vivo intrathecal passive transfer of affinity-purified human anti-amphiphysin autoantibodies in rats and revealed signs of markedly disabled clathrin-mediated endocytosis. This was unmasked at high synaptic activity and characterized by a reduction of the presynaptic vesicle pool, clathrin coated intermediates, and endosome-like structures. Super-resolution microscopy of inhibitory GABAergic presynaptic boutons in primary neurons revealed that specific human anti-amphiphysin immunoglobulin G induced an increase of the essential vesicular protein synaptobrevin 2 and a reduction of synaptobrevin 7. This constellation suggests depletion of resting pool vesicles and trapping of releasable pool vesicular proteins at the plasma membrane. Similar effects were found in amphiphysin-deficient neurons from knockout mice. Application of specific patient antibodies did not show additional effects. Blocking alternative pathways of clathrin-independent endocytosis with brefeldin A reversed the autoantibody induced effects on molecular vesicle composition. Endophilin as an interaction partner of amphiphysin showed reduced clustering within presynaptic terminals. Collectively, these results point towards an autoantibody-induced structural disorganization in GABAergic synapses with profound changes in presynaptic vesicle pools, activation of alternative endocytic pathways, and potentially compensatory rearrangement of proteins involved in clathrin-mediated endocytosis. Our findings provide novel insights into synaptic pathomechanisms in a prototypic antibody-mediated central nervous system disease, which may serve as a proof-of-principle example in this evolving group of autoimmune disorders associated with autoantibodies to synaptic antigens.

@article{werner2016human, abstract = {See Irani (doi:10.1093/awv364) for a scientific commentary on this article. Stiff-person syndrome is the prototype of a central nervous system disorder with autoantibodies targeting presynaptic antigens. Patients with paraneoplastic stiff-person syndrome may harbour autoantibodies to the BAR (Bin/Amphiphysin/Rvs) domain protein amphiphysin, which target its SH3 domain. These patients have neurophysiological signs of compromised central inhibition and respond to symptomatic treatment with medication enhancing GABAergic transmission. High frequency neurotransmission as observed in tonic GABAergic interneurons relies on fast exocytosis of neurotransmitters based on compensatory endocytosis. As amphiphysin is involved in clathrin-mediated endocytosis, patient autoantibodies are supposed to interfere with this function, leading to disinhibition by reduction of GABAergic neurotransmission. We here investigated the effects of human anti-amphiphysin autoantibodies on structural components of presynaptic boutons ex vivo and in vitro using electron microscopy and super-resolution direct stochastic optical reconstruction microscopy. Ultrastructural analysis of spinal cord presynaptic boutons was performed after in vivo intrathecal passive transfer of affinity-purified human anti-amphiphysin autoantibodies in rats and revealed signs of markedly disabled clathrin-mediated endocytosis. This was unmasked at high synaptic activity and characterized by a reduction of the presynaptic vesicle pool, clathrin coated intermediates, and endosome-like structures. Super-resolution microscopy of inhibitory GABAergic presynaptic boutons in primary neurons revealed that specific human anti-amphiphysin immunoglobulin G induced an increase of the essential vesicular protein synaptobrevin 2 and a reduction of synaptobrevin 7. This constellation suggests depletion of resting pool vesicles and trapping of releasable pool vesicular proteins at the plasma membrane. Similar effects were found in amphiphysin-deficient neurons from knockout mice. Application of specific patient antibodies did not show additional effects. Blocking alternative pathways of clathrin-independent endocytosis with brefeldin A reversed the autoantibody induced effects on molecular vesicle composition. Endophilin as an interaction partner of amphiphysin showed reduced clustering within presynaptic terminals. Collectively, these results point towards an autoantibody-induced structural disorganization in GABAergic synapses with profound changes in presynaptic vesicle pools, activation of alternative endocytic pathways, and potentially compensatory rearrangement of proteins