Activation of Rac1 by paxillin-Crk-DOCK180 signaling complex is antagonized by Rap1 in migrating NBT-II cells.
Induction of epithelial cell motility is a fundamental morphogenetic event that is recapitulated during carcinoma metastasis. Random motility of NBT-II carcinoma cells on collagen critically depends on paxillin phosphorylation at Tyr-31 and Tyr-118, the binding sites for the adapter protein CrkII. Two constitutive partners of CrkII are the exchange factors DOCK180 and C3G. CrkII bound to DOCK180 formed a signaling complex with phosphorylated paxillin that was necessary for cell migration as inferred from the inhibition caused by a DOCK180-interfering mutant. DOCK180, which acts predominantly on the Rho family GTPase Rac1, restored cell locomotion in cells expressing Phe-31/118 paxillin mutants deficient in Rac1 GTP-loading, suggesting that formation of paxillin-Crk-DOCK180 signaling complex controls collagen-dependent migration mainly through Rac1 activation. In migrating cells, CrkII constitutive association with C3G was not sufficient to stimulate its GDP/GTP exchange activity toward the Ras family GTPase Rap1. However, when constitutively active RapV12 was overexpressed, it negatively regulated cell motility. Activation of the C3G/Rap1 signaling pathway resulted in down-regulation of the paxillin-Crk-DOCK180 complex and reduction of Rac1-GTP, suggesting that Rap1 activation could suppress the Rac1 signaling pathway in epithelial cells.
Vallés
Ana M
AM
Unité Mixte Recherche 146, Centre National de la Recherche Scientifique, Bātiment 110, Centre Universitaire, 91405 Orsay, France. ana-maria.valles@curie.u-psud.fr
Beuvin
Maud
M
Boyer
Brigitte
B
D000818:Animals; D001665:Binding Sites; D015153:Blotting, Western; D002460:Cell Line; D045744:Cell Line, Tumor; D002465:Cell Movement; D003094:Collagen / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation; D004847:Epithelial Cells / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000378:metabolism; D047468:Immunoprecipitation; D009154:Mutation; D051419:Paxillin; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D050737:Proto-Oncogene Proteins c-crk; D051381:Rats; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection; D014443:Tyrosine / Q000737:chemistry; D020744:rac GTP-Binding Proteins / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein / Q000502:physiology*
C493872:Crk protein, rat; D003598:Cytoskeletal Proteins; C493871:DOCK180 protein, rat; D051419:Paxillin; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; D050737:Proto-Oncogene Proteins c-crk; C496063:Pxn protein, rat; D014443:Tyrosine; D003094:Collagen; D020558:GTP Phosphohydrolases; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein