title: Integrin alphavbeta3, requirement for VEGFR2-mediated activation of SAPK2/p38 and for Hsp90-dependent phosphorylation of focal adhesion kinase in endothelial cells activated by VEGF.
abstract: Endothelial cell migration, a key process in angiogenesis, requires the coordinated integration of motogenic signals elicited by the adhesion of endothelial cells to extracellular matrices and by angiogenic cytokines such as the vascular endothelial growth factor (VEGF). In this study, we found that addition of VEGF to human umbilical vein endothelial cells cultivated on vitronectin triggers a synergistic interaction between the VEGF receptor VEGFR2 and the clustered integrin receptor alphavbeta3. The interaction between VEGFR2 and alphavbeta3 is required for full phosphorylation of VEGFR2 and to drive the activation of motogenic pathways involving focal adhesion kinase (FAK) and stress-activated protein kinase-2/p38 (SAPK2/p38). The signal emanating from the VEGFR2 and alphavbeta3 interaction and leading to SAPK2/p38 activation proceeds directly from VEGFR2. The chaperone Hsp90 is found in a complex that coprecipitates with inactivated VEGFR2, and the association is increased by VEGF and decreased by geldanamycin, a specific inhibitor of Hsp90-mediated events. Geldanamycin also impairs the phosphorylation of FAK that results from the interaction between VEGFR2 and alphavbeta3, and this is accompanied by an inhibition of the recruitment of vinculin to VEGFR2. We conclude that a necessary cross talk should occur between VEGFR2 and the integrin alphavbeta3, to transduce the VEGF signals to SAPK2/p38 and FAK and that Hsp90 is instrumental in the building up of focal adhesions by allowing the phosphorylation of FAK and the recruitment of vinculin to VEGFR2.
authors.affiliation: Centre de recherche en cancérologie de l'Université Laval, L'Hôtel-Dieu de Québec, 9 rue McMahon, Québec, G1R 2J6, Canada.
authors.forename: Bénédicte
authors.initials: B
authors.lastname: Masson-Gadais
authors.forename: François
authors.initials: F
authors.lastname: Houle
authors.forename: Julie
authors.initials: J
authors.lastname: Laferrière
authors.forename: Jacques
authors.initials: J
authors.lastname: Huot
mesh_terms: D000911:Antibodies, Monoclonal; D016227:Benzoquinones; D002465:Cell Movement / Q000502:physiology; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D004789:Enzyme Activation; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D018014:Gene Transfer Techniques; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000819:agonists*; D047029:Lactams, Macrocyclic; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011809:Quinones / Q000494:pharmacology; D014471:Umbilical Veins / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000819:agonists*; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D000911:Antibodies, Monoclonal; D016227:Benzoquinones; D018841:HSP90 Heat-Shock Proteins; D039302:Integrin alphaVbeta3; D047029:Lactams, Macrocyclic; D011809:Quinones; D042461:Vascular Endothelial Growth Factor A; D011505:Protein-Tyrosine Kinases; D040301:Vascular Endothelial Growth Factor Receptor-2; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C001277:geldanamycin