Downregulation of Angiotensin II Type 1 Receptor by Hydrophobic 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase Inhibitors in Vascular Smooth Muscle Cells

Abstract

Abstract — 3-Hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors, so-called statins, reduce the relative risk of a major coronary event by lowering the serum cholesterol level. In addition, statins may confer beneficial effects by cholesterol-lowering independent mechanisms, which are incompletely characterized. Because angiotensin II (Ang II) plays crucial roles in the pathogenesis of cardiovascular diseases, we examined the effect of statins on the expression of the Ang II type 1 receptor (AT 1 -R) in cultured vascular smooth muscle cells (VSMCs). Cerivastatin and fluvastatin reduced the AT 1 -R mRNA and the AT 1 -R protein levels; however, pravastatin lacked this effect. Cerivastatin and fluvastatin suppressed the AT 1 -R promoter activity measured by luciferase assay but did not affect AT 1 -R mRNA stability, suggesting that the suppression occurs at the transcriptional level. Coincubation of VSMCs with mevalonate or geranylgeranyl pyrophosphate but not with farnesyl pyrophosphate reversed the cerivastatin-induced AT 1 -R downregulation. Overexpression of dominant-negative Rho A also suppressed AT 1 -R mRNA expression. Treatment with cerivastatin for 24 hours reduced the calcium response of VSMCs to Ang II. Taken together, statins downregulate AT 1 -R expression through a mevalonate-dependent, geranylgeranyl pyrophosphate-dependent, and Rho A-dependent manner and attenuate the biological function of Ang II. Downregulation of AT 1 -R may contribute to the cholesterol-independent beneficial effect of statins on the cardiovascular system.