Transforming Growth Factor-β1-mediated Inhibition of the flk-1/KDR Gene is Mediated by a 5′-Untranslated Region Palindromic GATA Site

Abstract

The angiogenic effects of vascular endothelial growth factor are mediated predominantly by the FLK-1/KDR receptor. An understanding of the transcriptional control mechanisms underlying flk-1/KDR expression should provide insight into the molecular basis of angiogenesis. In this study, we show that transforming growth factor-β1 (TGF-β 1) down-regulates expression of the endogenous flk-1/KDR gene in endothelial cells. In transient transfection assays, this effect was mapped to a palindromic GATA site in the 5′-untranslated region. In electrophoretic mobility shift assays, the palindromic GATA site was shown to bind to two molecules of GATA protein. Moreover, DNA-GATA interactions were inhibited by TGF-β1. Finally, in cotransfection assays, transactivation of the flk-1/KDR promoter by GATA-1 or GATA-2 was attenuated in TGF-β 1-treated cells. Taken together, these results suggest that the TGF-β-1-mediated inhibition of the flk-1/KDR gene is mediated by a 5′-untranslated region palindromic GATA site.