DFG Research Group FOR855

    Dual-layer translational control: understanding the msl-2 paradigm

    Prof. Dr. Matthias W. Hentze

    Project Summary:

    The translational regulation of Drosophila msl-2 mRNA by the RNA-binding proteins Sex-lethal (SXL) and Upstream-of-N-ras (UNR) has emerged as a model system to investigate the mechanims by which RNA-binding proteins control translation initiation. Using a cell-free system from Drosophila embryos, we have recapitulated this regulation and shown that binding of a SXL-UNR complex to the 3’ untranslated region (UTR) interferes with the recruitment of the 43S translation pre-initiation complex to the mRNA. We also found that SXL bound to the 5’UTR prevents ribosomal scanning, elaborating a first example of regulated scanning, and identifying a fail-safe mechanism of two independent, mutually reinforcing blocks to translation initiation. Using predominantly biochemical approaches, we want to examine the molecular details that underly both mechanisms of translational control. This will involve the establishment of methodological approaches that may well be applicable to other projects within the Forschergruppe. Scientifically, we hope to understand in unprecedented detail a dual layer regulatory mechanism acting via both UTRs.

    Selected publications (2007-09):

    1.    Duncan, K., M. Grskovic, C. Strein, K. Beckmann, R. Niggeweg, I. Abaza, F. Gebauer, M. Wilm and M.W. Hentze. Sex-lethal imparts a sex-specific function to UNR by recruiting it to the msl-2 mRNA 3’ UTR: translational repression for dosage compensation. Genes & Dev. 20, 368-379, 2006.

    2.    Thermann, R. and M.W. Hentze. Drosophila miR2 induces pseudo-polysomes and inhibits translation initiation. Nature 447, 875-879, 2007

    3.    Dankwardt, S., I. Kaufmann, M. Gentzel, K. Förstner, A.-S. Gantzert, N.H. Gehring, G. Neu-Yilik, P. Bork, W. Keller, M. Wilm, M.W. Hentze and A.E. Kulozik. Splicing factors stimulate polyadenylation via USEs  at non-canonical 3’ end formation signals. EMBO J. 26, 2658-2669, 2007

    4.    Till, S., E. Lejeune, R. Thermann, M. Bortfeld, M. Hothorn, D. Enderle, C. Heinrich, M.W. Hentze and A.G. Ladurner. A conserved motif in argonaute-interacting proteins mediates functional interactions through the argonaute PIWI domain. Nature Struc. Mol. Biol. 14, 897-903, 2007

    5.    Danckwardt, S., M.W. Hentze and A.E. Kulozik. 3’ end processing:molecular mechanisms and implications for health and disease. EMBO J. 27, 482-498, 2008

    6.    Ivanov, P.V., N.H. Gehring, J.B. Kunz, M.W. Hentze and A.E. Kulozik. Interactions between UPF1, eRFs, PABP and the exon-junction complex suggest an integrated model for mammalian NMD pathways. EMBO J. 27, 736-747, 2008

    7.    Beilharz , T.H., D.T. Humphreys, J.L. Clancy, R. Thermann, D.I.K. Martin, M.W. Hentze and T. Preiss. Rapid microRNA-mediated messenger RNA deadenylation contributes to translational repression in mammalian cells. PLoS ONE, in press, 2009

    8.    Gehring, N.H., S. Lamprinaki, M.W. Hentze and A.E. Kulozik. The hierarchy of exon-junction complex assembly by the spliceosome explains key features of mammalian nonsense-mediated mRNA decay. PLOS Biol. 7, e1000120. doi:10.1371/journal.pbio.1000120, 2009

    9.    Clerici, M., A. Mourao, I. Gutsche, N.H. Gehring, M.W. Hentze, A. Kulozik, J. Kadlec, M. Sattler and S. Cusack. Unusual bipartite mode of interaction between the nonsense decay factors UPF1 and UPF2. EMBO J 28, 2293-2306, 2009

    10.    Gehring, N.H., S. Lamprinaki, A.E. Kulozik  and M.W. Hentze. Disassembly of
    exon junction complexes by PYM. Cell 137, 536-548, 2009.

    11.   Duncan, K.E., C. Strein and M.W. Hentze. The SXL-UNR corepressor complex uses a PABP-mediated mechanism to inhibit ribosome recruitment to msl-2 mRNA. Mol. Cell 36, 571-582, 2009.