Cerivastatin prevents tumor necrosis factor-α-induced downregulation of endothelial nitric oxide synthase: role of endothelial cytosolic proteins

Abstract

Cardiovascular disease is accompanied by an impaired endothelium-dependent vasodilatory response. Loss of endothelial nitric oxide synthase (eNOS) expression may contribute to endothelial dysfunction. The aim of the present study was to analyze the effect of cerivastatin, a novel HMG CoA reductase inhibitor, on tumor necrosis factor-α (TNF-α)-induced downregulation of eNOS protein expression in bovine aortic endothelial cells (BAEC). TNF-α (10 ng/ml)- incubated BAEC showed a reduced expression of eNOS protein and decreased eNOS mRNA stabilization. This effect was associated with an increased binding activity of BAEC cytosolic proteins to the 3′-untranslated region (3′UTR) of eNOS mRNA. Cerivastatin prevented TNF-α-induced downregulation of eNOS protein expression in a concentration-dependent manner (10 −8 to 10 −5 M). Cerivastatin also prevented the binding of the cytosolic proteins to 3′-UTR of eNOS mRNA and was associated with eNOS mRNA stabilization. The reduced expression of eNOS protein by TNF-α was also prevented by coincubation with cycloheximide. In addition cycloheximide inhibited the binding activity of the cytosolic proteins to 3′-UTR of eNOS mRNA, suggesting the inducible character of the mentioned-cytosolic proteins. TNF-α stimulated the translocation of nuclear factor-κB (NF-κB), an effect that was not modified by cerivastatin. Furthermore, an inhibitor of NF-κB translocation, pyrrolidine dithiocarbamate failed to modify both the downregulation of eNOS expression and the increased binding activity of the cytosolic proteins to 3′-UTR of eNOS mRNA by TNF-α. The effect of cerivastatin on eNOS expression and the binding activity of the cytosolic proteins were reversed by coincubation with l-mevalonate. In conclusion, cerivastatin stabilized eNOS mRNA and upregulated eNOS expression in the endothelium, and this was associated with a decreased binding activity of cytosolic proteins to 3′-UTR of eNOS mRNA. The effect of cerivastatin on the regulation of eNOS expression was independent of NF-κB mobilization by TNF-α. These findings suggest that cerivastatin may have beneficial effects on the endothelial dysfunction associated with cardiovascular diseases beyond its effect on lowering cholesterol.