Mechanism of hyperpermeability induced by vascular endothelial growth factor in glomerular endothelial cells through Racl activation / 中华肾脏病杂志

ABSTRACT

Objective To investigate if Rac1 GTPase activation plays an important role in hyperpermeability and tyresine phosphorylation of tight junction induced by vascular endothelial growth factor (VEGF) in glomertdar endothelial cells (GEnCs). Methods Primary cultured rat endothelial cells were used as experimental model. The effect of VEGF at different concentrations (5 or 50 μg/L) on endothelial permeability was investigated by transendothelial electrical resistance (TEER). The permeability of GEnCs transfected with wild type Rac1 (wtRacl) or dominant negative Racl (N17Rac1) was also detected. Immune precipitation and immune blotting were used to detect the tyrosine phosphor-occludin in GEnCs. Results VEGF at high concentration (50 μg/L) induced hyperpermeability in GEnCs (P<0.05). At the same time, GTP-binding and membrane-bound Racl GTPase significantly increased(P<0.01)in GEnCs. Tyrosine phosphor-occludin was also increased (P<0.05) under VEGF stimulation. However, transfection of GEnCs with N17Rac1 dramatically attenuated the effect of VEGF on tyrosine phospho-occludin and endothelial cell permeability. Conclusions Increased VEGF can induce hyperpermeability in glomerular endothelial cells, which is related to occludin tyrosine phosphorylation through Racl activation. It provides a framework for understanding the role of VEGF-induced Racl-phospho-occludin pathway in the integrity of barrier function in the diabetic milieu.