Hepatocyte growth factor activates endothelial nitric oxide synthase by Ca2+- and phosphoinositide 3-kinase/Akt-dependent phosphorylation in aortic endothelial cells

Hepatocyte growth factor (HGF) causes endothelium-dependent vasodilation, but its relation to endothelial nitric oxide synthase (eNOS) activity remains to be elucidated. Treatment of bovine aortic endothelial cells with HGF increased eNOS activity within minutes, accompanied by an increase of activity-related site-specific phosphorylation of eNOS. The phosphorylation was completely abolished by pretreatment of the cells with a phosphoinositide 3-kinase (PI3K) inhibitor (wortmannin) and by transfection of dominant-negative Akt, and the enzyme activity was inhibited by wortmannin. In addition, eNOS activity and phos phorylation were abolished by pretreatment of the cells with an intracellular Ca2+-chelator, bis-(o-aminophenoxy)ethane-N,N, N',N'-tetra-acetic acid tetrakis(acetoxymethyl ester) (BAPTA/ AM), with a suppression of Akt phosphorylation. These results suggest that HGF stimulates eNOS activity by a PI3K/Akt-dependent phosphorylation in a Ca2+ -sensitive manner in vascular endothelial cells.