endothelin-1 and farnesyl-pyrophosphate

Statins are known to display benefits in various diseases independently from their cholesterol lowering properties. In this study, we investigated the acute effects of atorvastatin on vascular reactivity to various spasmogens in isolated rat aorta. The responses to noradrenaline (NA, 10(-8) -10(-4) m), endothelin-1 (ET-1, 10(-10) -10(-7) m), and potassium chloride (KCl, 10-100 mm) were evaluated in aortic rings pretreated with atorvastatin (10(-7) -10(-4) m, 30 min). To verify the mechanism of action, the effects of atorvastatin were studied in the presence of cholesterol precursor, mevalonate (10(-2) m, 45 min), mevalonate-derived isoprenoids, namely geranylgeranyl pyrophosphate (GGPP, 5 × 10(-6) m, 30 min) and farnesyl pyrophosphate (FPP, 5 × 10(-6) m, 30 min), and in the absence of endothelium. In parallel, aortic rings were pretreated with the specific inhibitor of Rho kinase, Y-27632 (10(-7) -10(-6) m). Atorvastatin significantly and concentration-dependently reduced the contractions to spasmogens in rat aorta. This acute inhibitory effect was also evident in endothelium-denuded rings. Pretreatment with mevalonate and GGPP, but not with FPP, reversed the inhibitory effect of atorvastatin (10(-4) m) on NA and ET-1 induced contractions. Similar to atorvastatin, pretreatment with Y-27632 inhibited the contractions to NA and KCl in a concentration-dependent manner. Western blot analysis revealed that both atorvastatin (10(-4) m) and Y-27632 (10(-6) m) pretreatment inhibited the phosphorylation of myosin phosphatase target subunit-1 (MYPT-1) triggered by NA, indicating an inhibitory influence on myosin phosphatase. In conclusion, atorvastatin displayed an acute inhibitory effect on vascular contractility evoked by various spasmogens and the inhibitory effect was possibly mediated by the inhibition of mevalonate and GGPP synthesis as well as the prevention of MYPT-1 phosphorylation induced by Rho/Rho kinase.

Topics: Amides; Animals; Aorta, Thoracic; Atorvastatin; Endothelin-1; Endothelium; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Male; Muscle, Smooth, Vascular; Myosin-Light-Chain Phosphatase; Norepinephrine; Phosphorylation; Polyisoprenyl Phosphates; Potassium Chloride; Prenylation; Protein Phosphatase 1; Pyridines; Rats; Rats, Wistar; rho-Associated Kinases; Sesquiterpenes

Endothelial dysfunction is characterized by an impaired vasodilatory response to endothelial agonists as well as by alterations in adhesion and coagulation processes. 3-Hydroxy-3-methylglutaryl-CoA reductase inhibitors (statins) have been shown to be useful in the reversal of endothelial dysfunction, an effect that may be independent of the reduction in cholesterol levels. Both the L-arginine-nitric oxide-cGMP and endothelin pathways are involved in the regulation of vascular tone. Here, we show that the basal transcription rate of the preproendothelin-1 gene was decreased by simvastatin (10 micromol/L) in bovine aortic endothelial cells. Transfection studies with the preproendothelin-1 gene promoter showed that mevalonate (100 micromol/L) was able to prevent the inhibitory effect mediated by simvastatin. Protein geranylgeranylation, but not farnesylation, proved to be crucial for a correct expression of the preproendothelin-1 gene. The C3 exotoxin from Clostridium botulinum that selectively inactivates Rho GTPases, the processing of which involves geranylgeranylation, reproduced the inhibitory effect of simvastatin on the expression of preproendothelin-1. Overexpression of dominant-negative mutants of RhoA and RhoB led to a significant reduction in the preproendothelin-1 promoter activity, whereas the expression of wild-type and constitutively active forms of these proteins resulted in an increase, in support that Rho proteins are required for the basal expression of the preproendothelin-1 gene. Finally, we show that the Rho-dependent activation of the preproendothelin-1 gene transcription was inhibited by simvastatin. Thus, the control of vascular tone and proliferative response mediated by endothelin-1 is regulated at multiple levels, among which the Rho proteins play an essential role.

Topics: Alkyl and Aryl Transferases; Animals; Cattle; Cells, Cultured; Drug Interactions; Endothelin-1; Endothelins; Endothelium, Vascular; Farnesyltranstransferase; Gene Expression Regulation; Mevalonic Acid; Nitric Oxide; Polyisoprenyl Phosphates; Protein Precursors; rho GTP-Binding Proteins; Sesquiterpenes; Simvastatin; Transcription, Genetic