Involvement of Rho GTPases in the transcriptional inhibition of preproendothelin-1 gene expression by simvastatin in vascular endothelial cells

Endothelial dysfunction is characterized by an impaired vasodilatory respon se to endothelial agonists as well. as by alterations in adhesion and coagu lation processes. 3-Hydroxy-3-methylglutaryl-CoA reductase inhibitors (stat ins) have been shown to be useful in the reversal of endothelial dysfunctio n, an effect that may be independent of the reduction in cholesterol levels . Both the L-arginine-nitric oxide-cGMP and endothelin pathways are involve d in the regulation of vascular tone. Here, we show that the basal transcri ption rate of the preproendothelin-l gene was decreased by simvastatin (10 mu mol/L) in bovine aortic endothelial cells. Transfection studies with the preproendothelin-l gene promoter showed that mevalonate (100 mu mol/L) was able to prevent the inhibitory effect mediated by simvastatin. Protein ger anylgeranylation, but not farnesylation, proved to be crucial for a correct expression of the preproendothelin-1 gene. The C3 exotoxin from Clostridiu m botulinum that selectively inactivates Rho GTPases, the processing of whi ch involves geranylgeranylation, reproduced the inhibitory effect of simvas tatin on the expression of preproendothelin-1. Overexpression of dominant-n egative mutants of RhoA and RhoB led to a significant reduction in the prep roendothelin-l promoter activity, whereas the expression of wild-type and c onstitutively active forms of these proteins resulted in an increase, in su pport that Rho proteins are required for the basal expression of the prepro endothelin-l gene. Finally, we show that the Rho-dependent activation of th e preproendothelin-l gene transcription was inhibited by simvastatin. Thus, the control of vascular tone and proliferative response mediated by endoth elin-l is regulated at multiple levels, among which the Rho proteins play a n essential role.