title: VEGF(121) and VEGF(165) regulate blood vessel diameter through vascular endothelial growth factor receptor 2 in an in vitro angiogenesis model.
abstract: Vascular endothelial growth factor (VEGF) is essential for the induction of angiogenesis and drives both endothelial cell (EC) proliferation and migration. It has been suggested that VEGF also regulates vessel diameter, although this has not been tested explicitly. The two most abundant isoforms, VEGF(121) and VEGF(165), both signal through VEGF receptor 2 (VEGFR-2). We recently optimized a three-dimensional in vitro angiogenesis assay using HUVECs growing on Cytodex beads and embedded in fibrin gels. Fibroblasts provide critical factors that promote sprouting, lumen formation, and vessel stability. Using this assay, we have examined the role of VEGF in setting vessel diameter. Low concentrations of both VEGF(121) and VEGF(165) promote growth of long, thin vessels, whereas higher concentrations of VEGF remarkably enhance vessel diameter. Placental growth factor, which binds to VEGFR-1 but not VEGFR-2, does not promote capillary sprouting. Moreover, specific inhibition of VEGFR-2 signaling results in a dramatic reduction of EC sprouting in response to VEGF, indicating the critical importance of this receptor. The increase in vessel diameter is the result of cell proliferation and migration, rather than cellular hypertrophy, and likely depends on MEK1-ERK1/2 signaling. Both phosphatidylinositol 3-kinase and p38 activity are required for cell survival. We conclude that the diameter of new capillary sprouts can be determined by the local concentration of VEGF and that the action of VEGF on angiogenic EC in this assay is critically dependent on signaling through VEGFR-2.
authors.affiliation: Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, California 92697, USA.
authors.forename: Martin N
authors.initials: MN
authors.lastname: Nakatsu
authors.forename: Richard C A
authors.initials: RC
authors.lastname: Sainson
authors.forename: Sofía
authors.initials: S
authors.lastname: Pérez-del-Pulgar
authors.forename: Jason N
authors.initials: JN
authors.lastname: Aoto
authors.forename: Mark
authors.initials: M
authors.lastname: Aitkenhead
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Taylor
authors.forename: Philip M
authors.initials: PM
authors.lastname: Carpenter
authors.forename: Christopher C W
authors.initials: CC
authors.lastname: Hughes
mesh_terms: D043925:Angiogenesis Inducing Agents / Q000494:pharmacology*; D002196:Capillaries / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development; D002465:Cell Movement / Q000187:drug effects; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D048369:MAP Kinase Kinase 1; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D000072483:Placenta Growth Factor; D011257:Pregnancy Proteins / Q000378:metabolism / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D014471:Umbilical Veins / Q000166:cytology; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism*
chemical_list: D043925:Angiogenesis Inducing Agents; D004791:Enzyme Inhibitors; D005419:Flavonoids; C000608036:PGF protein, human; D011257:Pregnancy Proteins; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D000072483:Placenta Growth Factor; D040301:Vascular Endothelial Growth Factor Receptor-2; D017346:Protein Serine-Threonine Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; C482125:MAP2K1 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one