title: Pressure activates colon cancer cell adhesion via paxillin phosphorylation, Crk, Cas, and Rac1.
abstract: Physical forces can activate colon cancer cell adhesion, critical for metastasis. Paxillin is phosphorylated by FAK and required for pressure-stimulated adhesion. However, whether paxillin acts as an inert scaffolding protein or whether paxillin phosphorylation is required is unknown. Transfection with paxillin point-phosphorylation mutants demonstrated that phosphorylation at tyrosines 31 and 118 together is necessary for pressure-stimulated adhesion. We further evaluated potential paxillin partners. Reducing the adaptor protein Crk or the focal adhesion protein p130Cas blocked pressure-stimulated adhesion. Furthermore, Crk and p130Cas both displayed increased co-immunoprecipitation with paxillin in response to increased pressure, except in cells transfected with a Y31Y118 paxillin mutant. Inhibiting the small GTPase Rac1 also abolished pressure-stimulated adhesion, and reducing paxillin by siRNA blocked Rac1 phosphorylation by pressure. Thus, paxillin phosphorylation at tyrosines 31 and 118 together is necessary for pressure-induced adhesion. Paxillin, Crk and Cas form a trimeric complex that activates Rac1 and mediates this effect.
authors.affiliation: Department of Surgery, John D. Dingell VA Medical Center and Wayne State University, 4646 John R. Street, Detroit, MI 48201, USA.
authors.forename: C
authors.initials: C
authors.lastname: Downey
authors.forename: D H
authors.initials: DH
authors.lastname: Craig
authors.forename: M D
authors.initials: MD
authors.lastname: Basson
mesh_terms: D000185:Actinin / Q000037:antagonists & inhibitors; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000378:metabolism* / Q000473:pathology; D050719:Crk-Associated Substrate Protein / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006801:Humans; D009362:Neoplasm Metastasis; D051419:Paxillin / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D011312:Pressure; D050737:Proto-Oncogene Proteins c-crk / Q000037:antagonists & inhibitors / Q000378:metabolism*; D034622:RNA Interference; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*
chemical_list: D050719:Crk-Associated Substrate Protein; D051419:Paxillin; D050737:Proto-Oncogene Proteins c-crk; D000185:Actinin; D014443:Tyrosine; D020830:rac1 GTP-Binding Protein