A novel MET-interacting protein shares high sequence similarity with RanBPM, but fails to stimulate MET-induced Ras/Erk signaling.
MET is a receptor protein tyrosine kinase for hepatocyte growth factor, a multifunctional cytokine controlling cell growth, morphogenesis, and motility. In our previous study, RanBPM/RanBP9, whose name originated from its ability to interact with Ran, was identified as a MET-interacting protein. RanBPM/RanBP9 activates the Ras/Erk signaling pathway by serving as an adaptor protein of MET to recruit Sos. In this study, we identify a protein sharing a high amino acid sequence identity with RanBPM/RanBP9, especially in its SPRY domain, the region responsible for MET binding. This protein lacks the N-terminal poly-proline and poly-glutamine (Poly-PQ) stretch present in RanBPM/RanBP9 and has less homology with RanBPM/RanBP9 in its mid-region. We subsequently named this protein RanBP10 after demonstrating its interaction with Ran. We show that, like RanBPM/RanBP9, RanBP10 interacts with the tyrosine kinase domain of MET via its SPRY domain and these two proteins can compete with each other to bind to MET. Interestingly, unlike RanBPM/RanBP9, overexpression of RanBP10 cannot induce Erk1/2 phosphorylation and serum response element-luciferase (SRE-LUC) reporter gene expression. More importantly, co-transfection of RanBPM/RanBP9 and RanBP10 significantly represses SRE-LUC reporter gene expression induced by overexpression of RanBPM/RanBP9. Additional binding assays demonstrate that RanBP10 fails to interact with Sos, which explains its inability to activate the Ras/Erk pathway. Furthermore, we show that the N-terminus of RanBPM/RanBP9 with the Poly-PQ stretch is required for recruiting Sos and a truncated RanBPM/RanBP9 lacking this region fails to recruit Sos, indicating that the functional difference between RanBP10 and RanBPM/RanBP9 lies in their sequence difference in their N-termini.
Wang
Dakun
D
Department of Urology, University of Rochester Medical Center, Rochester, NY 14642, USA.
Li
Zaibo
Z
Schoen
Susan R
SR
Messing
Edward M
EM
Wu
Guan
G
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D001667:Binding, Competitive; D002460:Cell Line; D003598:Cytoskeletal Proteins; D004789:Enzyme Activation / Q000187:drug effects; D017930:Genes, Reporter; D005982:Glutathione Transferase / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D011233:Precipitin Tests; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D027602:Serum Response Element / Q000235:genetics; D015398:Signal Transduction / Q000502:physiology; D020664:Son of Sevenless Proteins / Q000378:metabolism; D020931:ran GTP-Binding Protein / Q000235:genetics* / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; D003598:Cytoskeletal Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; C116005:Ran binding protein 9; D020664:Son of Sevenless Proteins; D008156:Luciferases; D005982:Glutathione Transferase; D019859:Proto-Oncogene Proteins c-met; D020928:Mitogen-Activated Protein Kinases; D020931:ran GTP-Binding Protein