Src mediates stimulation by vascular endothelial growth factor of the phosphorylation of focal adhesion kinase at tyrosine 861, and migration and anti-apoptosis in endothelial cells
R. Abu-ghazaleh et al., Src mediates stimulation by vascular endothelial growth factor of the phosphorylation of focal adhesion kinase at tyrosine 861, and migration and anti-apoptosis in endothelial cells, BIOCHEM J, 360, 2001, pp. 255-264
Vascular endothelial growth factor (VEGF) stimulates the tyrosine phosphory
lation of focal adhesion kinase (FAK), increases focal adhesion formation a
nd is chemotactic for human umbilical-vein endothelial cells (HUVECs). In t
he present study we identified the major sites of VEGF-induced FAK tyrosine
phosphorylation and investigated the mechanism mediating this pathway in t
he action of VEGF. VEGF increased the focal adhesion localization of FAK ph
osphorylated at Tyr-397 (Y397) and Y861 but stimulated a marked increase in
phosphorylation at Y861 without significantly affecting the total level of
phospho-Y397 FAK. Inhibition of Src with the specific inhibitor 4-amino-5-
(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP2) completely bloc
ked VEGF-induced Y861 phosphorylation without decreasing the level of phosp
ho-Y397 FAK. We also examined the role of Src in mediating endothelial func
tions of VEGF in which FAK has been implicated as having a role. PP2 marked
ly inhibited V-EGF-induced chemotaxis and wound-healing cell migration. The
Src inhibitor also decreased the anti-apoptotic effect of VEGF determined
by surface staining of annexin V but did not increase FAK proteolysis or pr
event the VEGF-dependent inhibition of FAK proteolysis. In contrast, the sp
ecific PtdIns 3-kinase inhibitor LY294002 induced apoptosis and markedly de
creased p125(FAK) expression and increased FAK proteolysis but had little e
ffect on Y861 phosphorylation. These findings identify Src-dependent FAK ph
osphorylation at Y861 as a novel VEGF-induced signalling pathway in endothe
lial cells and suggest that this pathway might be involved in the mechanism
s mediating VEGF-induced endothelial cell migration and anti-apoptosis.