Role of endothelial nitric oxide synthase in endothelial cell migration.
Endothelium-derived nitric oxide (NO) and its precursor L-arginine have been implied to promote angiogenesis, but little is known about the precise mechanism. The inhibition of endogenous NO formation by Nomega-nitro-L-arginine methyl ester (L-NAME) (1 mmol/L) but not its inactive enantiomer D-NAME (1 mmol/L) inhibited endothelial cell sprouting from the scratched edge of the cultured bovine aortic endothelial cell monolayer. Inhibition of endogenous NO release by L-NAME was confirmed by amperometric measurement using an NO-specific electrode. In the modified Boyden chamber, L-NAME (1 mmol/L) significantly inhibited endothelial cell migration, whereas L-NAME did not affect endothelial DNA synthesis as assessed by analysis of [3H]thymidine incorporation. We then examined alteration of endothelial cell adhesion molecule expression after the inhibition of NO by L-NAME in cultured human umbilical vein endothelial cells. In both normoxic and hypoxic conditions, L-NAME (1 mmol/L) inhibited surface expression of integrin alphavbeta3, which is an important integrin facilitating endothelial cell survival and angiogenesis. However, L-NAME did not affect the expression of platelet endothelial cell adhesion molecule-1, intercellular adhesion molecule-1, vascular endothelial adhesion molecule-1, gap junction protein connexin 43, and VE-cadherin, which have been reported to potentially affect angiogenesis. In summary, inhibition of endothelial NO synthase by L-NAME attenuated endothelial cell migration but not proliferation in vitro. Furthermore, endogenous endothelium-derived NO maintains the functional expression of integrin alphavbeta3, a mediator for endothelial migration, survival, and angiogenesis. Endothelium-derived NO, thus, may play an important role in mediating angiogenesis by supporting endothelial cell migration, at least partly, via an integrin-dependent mechanism.
D000818:Animals; D015703:Antigens, CD; D001011:Aorta; D001120:Arginine / Q000378:metabolism; D015820:Cadherins / Q000096:biosynthesis; D002417:Cattle; D015687:Cell Hypoxia; D002465:Cell Movement; D002478:Cells, Cultured; D018031:Connexin 43 / Q000096:biosynthesis; D004730:Endothelium, Vascular / Q000166:cytology* / Q000293:injuries / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D018919:Neovascularization, Physiologic; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000502:physiology*; D052250:Nitric Oxide Synthase Type III; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000096:biosynthesis; D019030:Receptors, Vitronectin / Q000096:biosynthesis; D013237:Stereoisomerism; D014471:Umbilical Veins; D019010:Vascular Cell Adhesion Molecule-1 / Q000096:biosynthesis; D000099152:Cadherin 5