Vascular endothelial growth factor (VEGF) enhances the expression of receptors and activates mitogen-activated protein (MAP) kinase of dog retinal capillary endothelial cells

Since the galactose-fed dog is an animal model that develops the advanced s tage of proliferative retinopathy, the effects of vascular endothelial grow th factor (VEGF) on cell growth, receptor expression and the activation of mitogen-activated protein (MAP) kinase pathway of dog retinal capillary end othelial cells were investigated. Dog retinal endothelial cells were cultur ed at 37 degrees C under 5% carbon dioxide atmosphere in CS-C medium supple mented with endothelial cell growth factor(ECGF). VEGF receptor expression was examined by RT-PCR, and activation of MAP kinase was examined with anti body against phospho-Elk-l (Ser383). When growth factors were removed from the culture medium, cell survival of dog endothelial cells was significantl y reduced. Addition of VEGF protected these cells from cell death induced b y growth factor starvation. VEGF also enhanced tube formation in dog endoth elial cells and increased the expression of two VEGF receptors, Flt-1 and K DR/Flk-1. Cells treated with VEGF also displayed the phosphorylation of the transcription factor, Elk-1. Addition of the tyrosine kinase inhibitor, ge nistein, eliminated VEGF-induced cell growth and Elk-1 phosphorylation. The se data confirm that cell growth and tube formation of dog retinal capillar y endothelial cells are stimulated by VEGF. VEGF also increases the express ion of the receptors, KDR and Flt-1, and activates the p44/42 MAP kinase pa thway.