Peroxide-Inducible Ets-1 Mediates Platelet-Derived Growth Factor Receptor-α Gene Transcription in Vascular Smooth Muscle Cells

Platelet-derived growth factor (PDGF) has been implicated in the pathogenesis of vascular occlusive disorders such as atherosclerosis and restenosis in part due to its regulation of smooth muscle cell phenotype. The molecular mechanisms regulating the expression of PDGF-Rα, which binds all known dimeric forms of PDGF except PDGF-DD, are poorly understood. Here we demonstrate that the winged helix-turn-helix proto-oncogene Ets-1 controls PDGF-Rα transcription and mRNA expression in smooth muscle cells. Mutational analysis, electrophoretic mobility shift assay, and chromatin immunoprecipitation revealed the existence of a reverse Ets binding motif (−45TTCC−42) in the proximal region of the PDGF-Rα promoter, which bound both recombinant and endogenous Ets-1. Ets-1-inducible PDGF-Rα expression depended on the integrity of both the −45TTCC−42 motif and the −61G10−52 element, which resides upstream of −45TTCC−42 and mediates Sp1 induction. Hydrogen peroxide (H2O2) at nanomolar concentrations stimulated levels of Ets-1 and increased PDGF-Rα transcription and mRNA expression without affecting Sp1 expression. H2O2 activation of the PDGF-Rα promoter was abolished by disrupting −45TTCC−42 or −61G10−52. These studies identify a functional Ets motif in the PDGF-Rα promoter that plays a pivotal role in agonist-inducible PDGF-Rα transcription.