title: Compartmentalizing VEGF-induced ERK2/1 signaling in placental artery endothelial cell caveolae: a paradoxical role of caveolin-1 in placental angiogenesis in vitro.
abstract: On vascular endothelial growth factor (VEGF) stimulation, both VEGF R1 and R2 receptors were phosphorylated in ovine fetoplacental artery endothelial (oFPAE) cells. Treatment with VEGF stimulated both time- and dose-dependent activation of ERK2/1 in oFPAE cells. VEGF-induced ERK2/1 activation was mediated by VEGFR2, but not VEGFR1, and was linked to intracellular calcium, protein kinase C, and Raf-1. VEGF stimulated oFPAE cell proliferation, migration, and tube formation in vitro. Blockade of ERK2/1 pathway attenuated VEGF-induced cell proliferation and tube formation but failed to inhibit migration in oFPAE cells. Disruption of caveolae by cholesterol depletion with methyl-beta-cyclodextrin or by down-regulation of its structural protein caveolin-1 blunted VEGF-induced ERK2/1 activation, proliferation, and tube formation in oFPAE cells, indicating an essential role of integral caveolae in these VEGF-induced responses. Adenoviral overexpression of caveolin-1 and addition of a caveolin scaffolding domain peptide also inhibited VEGF-stimulated ERK2/1 activation, cell proliferation, and tube formation in oFPAE cells. Furthermore, molecules comprising the ERK2/1 signaling module, including VEGFR2, protein kinase Calpha, Raf-1, MAPK kinase 1/2, and ERK2/1, resided with caveolin-1 in caveolae. VEGF transiently stimulated ERK2/1 activation in the caveolae similarly as in intact cells. Caveolae disruption greatly diminished ERK2/1 activation by VEGF in oFPAE cell caveolae. We conclude that caveolae function as a platform for compartmentalizing the VEGF-induced ERK2/1 signaling module. Caveolin-1 and caveolae play a paradoxical role in regulating VEGF-induced ERK2/1 activation and in vitro angiogenesis as evidenced by the similar inhibitory effects of down-regulation and overexpression of caveolin-1 and disruption of caveolae in oFPAE cells.
authors.affiliation: Department of Reproductive Medicine, University of California, San Diego, La Jolla, California 92093, USA.
authors.forename: Wu-Xiang
authors.initials: WX
authors.lastname: Liao
authors.forename: Lin
authors.initials: L
authors.lastname: Feng
authors.forename: Honghai
authors.initials: H
authors.lastname: Zhang
authors.forename: Jing
authors.initials: J
authors.lastname: Zheng
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Moore
authors.forename: Dong-Bao
authors.initials: DB
authors.lastname: Chen
mesh_terms: D000818:Animals; D001158:Arteries / Q000378:metabolism*; D051242:Caveolin 1 / Q000378:metabolism*; D042783:Endothelial Cells / Q000166:cytology*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D008954:Models, Biological; D009389:Neovascularization, Pathologic; D010920:Placenta / Q000098:blood supply / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
chemical_list: D051242:Caveolin 1; D042461:Vascular Endothelial Growth Factor A; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3