title: The scaffolding adapter Gab1 mediates vascular endothelial growth factor signaling and is required for endothelial cell migration and capillary formation.
abstract: Vascular endothelial growth factor (VEGF) is involved in the promotion of endothelial cell proliferation, migration, and capillary formation. These activities are mainly mediated by the VEGFR2 receptor tyrosine kinase that upon stimulation, promotes the activation of numerous proteins including phospholipase Cgamma (PLCgamma), phosphatidylinositol 3-kinase (PI3K), Akt, Src, and ERK1/2. However, the VEGFR2-proximal signaling events leading to the activation of these targets remain ill defined. We have identified the Gab1 adapter as a novel tyrosine-phosphorylated protein in VEGF-stimulated cells. In bovine aortic endothelial cells, Gab1 associates with VEGFR2, Grb2, PI3K, SHP2, Shc, and PLCgamma, and its overexpression enhances VEGF-dependent cell migration. Importantly, silencing of Gab1 using small interfering RNAs leads to the impaired activation of PLCgamma, ERK1/2, Src, and Akt; blocks VEGF-induced endothelial cell migration; and perturbs actin reorganization and capillary formation. In addition, co-expression of VEGFR2 with Gab1 mutants unable to bind SHP2 or PI3K in human embryonic kidney 293 cells and bovine aortic endothelial cells mimics the defects observed in Gab1-depleted cells. Our work thus identifies Gab1 as a novel critical regulatory component of endothelial cell migration and capillary formation and reveals its key role in the activation of VEGF-evoked signaling pathways required for angiogenesis.
authors.affiliation: Centre de Recherche du Centre Hospitalier de l'Université de Montréal/Institut du Cancer de Montréal and Département de Médecine de l'Université de Montréal, Montréal, Québec H2L 4M1, Canada.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Laramée
authors.forename: Catherine
authors.initials: C
authors.lastname: Chabot
authors.forename: Monikca
authors.initials: M
authors.lastname: Cloutier
authors.forename: Raphaëlle
authors.initials: R
authors.lastname: Stenne
authors.forename: Marina
authors.initials: M
authors.lastname: Holgado-Madruga
authors.forename: Albert J
authors.initials: AJ
authors.lastname: Wong
authors.forename: Isabelle
authors.initials: I
authors.lastname: Royal
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000502:physiology*; D000818:Animals; D001011:Aorta / Q000166:cytology*; D002196:Capillaries / Q000378:metabolism; D002417:Cattle; D002460:Cell Line; D002465:Cell Movement; D042783:Endothelial Cells / Q000166:cytology*; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D008954:Models, Biological; D016297:Mutagenesis, Site-Directed; D009389:Neovascularization, Pathologic; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051966:Phospholipase C gamma / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C098587:GAB1 protein, human; D042461:Vascular Endothelial Growth Factor A; D019869:Phosphatidylinositol 3-Kinases; D040301:Vascular Endothelial Growth Factor Receptor-2; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D051966:Phospholipase C gamma