title: Erbin inhibits RAF activation by disrupting the sur-8-Ras-Raf complex.
abstract: Erbin is a member of the LAP (leucine-rich repeat (LRR) and PDZ domain) family. It inhibits Ras-mediated activation of ERK in response to growth factors. In this study, we investigated the mechanisms by which Erbin regulates the Ras-Raf-MEK pathway. The N-terminal LRR domain was necessary and sufficient to inhibit neuregulin-activated expression of epsilon416-Luc, a reporter of ERK activation. On the other hand, Erbin had no effect on Ras activation, but it attenuated neuregulin-induced Raf activation, suggesting that Erbin may regulate Raf activation by Ras. Via the LRR domain, Erbin interacts with Sur-8, a scaffold protein necessary for the Ras-Raf complex. Expression of Erbin attenuated the interaction of Sur-8 with active Ras and Raf. Moreover, Erbin-shRNA, which suppressed Erbin expression at mRNA and protein levels, increased the interaction of Sur-8 with Ras and Raf, ERK activation, and neuregulin-induced expression of endogenous acetylcholine receptor epsilon-subunit mRNA. These results demonstrate a regulatory role of Erbin in the Ras-Raf-MEK pathway, suggesting that Erbin may inhibit ERK activation by disrupting the Sur-8-Ras/Raf interaction.
authors.affiliation: Program of Developmental Neurobiology, Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, 30912, USA.
authors.forename: Penggao
authors.initials: P
authors.lastname: Dai
authors.forename: Wen C
authors.initials: WC
authors.lastname: Xiong
authors.forename: Lin
authors.initials: L
authors.lastname: Mei
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D019556:COS Cells; D002352:Carrier Proteins / Q000378:metabolism / Q000502:physiology*; D002460:Cell Line; D002522:Chlorocebus aethiops; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D047908:Intracellular Signaling Peptides and Proteins; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D020890:Neuregulin-1 / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism*; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C413364:ERBIN protein, human; D047908:Intracellular Signaling Peptides and Proteins; D020890:Neuregulin-1; D012333:RNA, Messenger; D012097:Repressor Proteins; C112913:SHOC2 protein, human; D005346:Fibroblast Growth Factors; D012313:RNA; D006160:Guanosine Triphosphate; D008156:Luciferases; D019908:Proto-Oncogene Proteins c-raf