Universität zu Köln 

Dr. Niels Gehring

Institut für Genetik, Universität zu Köln
email: ngehring@uni-koeln.de
phone: +49-(0)221 470 3873
website

Nonsense mediated mRNA decay (NMD) is a quality control mechanism that eliminates aberrant transcripts and thereby protects cells and organisms from potentially harmful products of mutant genes. The central NMD protein UPF1 plays an important role during the detection and degradation phases of NMD. UPF1 function requires a cycle of phosphorylation (executed by its kinase SMG1) and dephosphorylation by PP2A that is specifically stimulated by the proteins SMG5, SMG6 and SMG7. In addition to their function in UPF1 dephosphorylation, SMG5, 6 and 7 associate with hyperphosphorylated forms of UPF1. This binding initiates the degradation of the nonsense containing mRNA, because SMG5 and 7 interact with the mRNA degradation machinery and SMG6 possesses intrinsic endonuclease activity. Hence, the formation of the UPF1-SMG5/6/7 complex represents the ultimate step of NMD. Several putative phosphorylation sites within UPF1 are predicted by in silico analyses, but the importance of individual sites has not been addressed. We will employ a combination of mass spectrometry and screening of a library of phosphorylated and non-phosphorylated peptides to identify the motifs within UPF1 that are recognised by SMG5/6/7. Furthermore, we will investigate if the complex formation requires cooperative binding between UPF1 and SMG5/6/7 to enhance the specific recognition of only phosphorylated forms of UPF1 by SMG5/6/7. Finally, the importance of complex formation for NMD will be assessed using functional NMD assays.

Running time: 07/2011 – 06/2015

Recent publications:

Boehm, V., Haberman, N., Ottens, F., Ule, J., Gehring, N.H. (2014). 3' UTR length and messenger ribonucleoprotein composition determine endocleavage efficiencies at termination codons. Cell Rep. 9(2), 555-68. Pubmed

Fatscher, T., Boehm, V., Weiche, B., Gehring, N.H. (2014). The interaction of cytoplasmic poly(A)-binding protein with eukaryotic initiation factor 4G suppresses nonsense-mediated mRNA decay. RNA. 2014 Aug 21. [Epub ahead of print] Pubmed

Clerici, M., Deniaud, A., Boehm, V., Gehring, N.H., Schaffitzel, C., and Cusack, S. (2014). Structural and functional analysis of the three MIF4G domains of nonsense-mediated decay factor UPF2. Nucl. Acids Res. 42, 2673-86. PubMed

Gehring, N.H., Lamprinaki, S., Hentze, M.W., and Kulozik, A.E. (2009). The hierarchy of exon-junction complex assembly by the spliceosome explains key features of mammalian nonsense-mediated mRNA decay. PLoS Biol. 7 (5):e1000120.

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

Gehring, N.H., Hentze, M.W., and Kulozik, A.E. (2008). Tethering assays to investigate nonsense-mediated mRNA decay activating proteins. Meth. Enzymol. 448, 467-482.

Gehring, N.H., Kunz, J.B., Neu-Yilik, G., Breit, S., Viegas, M.H., Hentze, M.W., and Kulozik, A.E. (2005). Exon-junction complex components specify distinct routes of nonsense-mediated mRNA decay with differential cofactor requirements. Mol. Cell 20, 65-75.

Gehring, N.H., Neu-Yilik, G., Schell, T., Hentze, M.W., and Kulozik, A.E. (2003). Y14 and hUpf3b form an NMD-activating complex. Mol. Cell 11, 939-949.

Neu-Yilik, G., Gehring, N.H., Thermann, R., Frede, U., Hentze, M.W., and Kulozik, A.E. (2001). Splicing and 3' end formation in the definition of nonsense-mediated decay-competent human beta-globin mRNPs. EMBO J. 20, 532-540.