Scaffolding adapter protein Gab1 impairs bFGF-induced bio-activity via affecting PI3K-AKT pathway.

The role of Grb2-associated binder 1 (Gab1) in bFGF-activated PI3K-AKT pathway of endothelial cells remains largely unknown. To elucidate this role, a set of studies with siRNA knockdown of Gab1 was performed. Knockdown of Gab1 using siRNA was performed in fused endothelial cell line EA.hy926 and the low level of Gab1 was confirmed with quantitative R-T PCR and Western blotting. Effects of Gab1 down-regulation were examined on several aspects: bFGF-induced AKT phosphorylation, proliferation, migration and vessel tubing formation of EA.hy926 cells. The bFGF-induced AKT phosphorylation of wild-type EA.hy926 cells was both dose-dependent and time dependent with a peak at 10 ng/ml and about 30 min after bFGF treatment. The AKT activation was significantly reduced in Gab1 siRNA-treated EA.hy926 cells. The blocking of Gab1-AKT path resulted in a set of biological alterations of EA.hy926 cells: (i) reduced proliferation; (ii) impaired migration; (iii) decreased vessel tubing formation in both 2D and 3D culture. All data support that Gab1 is associated with angiogenesis function of EA.hy926 endothelium cells via PI3K-Akt signaling pathway.