geranylgeranyl-pyrophosphate and Fibrosis

In our previous study, farnesyl pyrophosphate synthase (FPPS) was shown to be increased in spontaneously hypertensive rats (SHR) and in mice with angiotensin-II induced cardiac hypertrophy. Overexpression of FPPS induced cardiac hypertrophy and fibrosis in mice, accompanied by an increase in the synthesis of farnesyl pyrophosphate (FPP) and geranylgeranyl pyrophosphate (GGPP). In the present study, we investigated the mechanisms of reversing cardiovascular remodeling in SHR by inhibiting FPPS.. Six-week-old rats were given vehicle or an FPPS inhibitor (alendronate, 100 ug/kg/d) daily for twelve weeks by osmotic mini-pump. The results demonstrated that FPPS inhibition attenuated cardiac hypertrophy and fibrosis in SHR as shown by the heart weight to body weight ratio, echocardiographic parameters, and histological examination. In addition, FPPS inhibition attenuated aortic remodeling as shown by reduced media thickness, media cross-sectional area and collagen of the aorta as well as SBP, DBP, MBP. Furthermore, 12 weeks of alendronate treatment significantly decreased FPP and GGPP levels, RhoA activation and geranylgeranylation in the heart and aorta, all of which were significantly upregulated in SHR compared with normotensive Wistar-Kyoto rats.. Taken together, these results indicate that chronic treatment with alendronate decreases the development of cardiac and aortic remodeling, by a pathway which involves inhibition of the geranylgeranylation and activation of RhoA.

Topics: Alendronate; Animals; Aorta; Blood Pressure; Bone Density Conservation Agents; Cardiomegaly; Collagen; Echocardiography; Fibrosis; Geranyltranstransferase; Male; Myocardium; Polyisoprenyl Phosphates; Prenylation; Rats, Inbred SHR; Rats, Inbred WKY; rhoA GTP-Binding Protein; Sesquiterpenes; Species Specificity; Vascular Remodeling; Ventricular Remodeling

Accumulating evidence suggests that hydroxymethylglutaryl-CoA reductase inhibitors have many biological effects beyond reducing cholesterol synthesis. In a mouse model of renal interstitial fibrosis induced by unilateral ureteral obstruction, fluvastatin, one of the lipophilic hydroxymethylglutaryl-CoA reductase inhibitors, was shown to ameliorate fibrosis.. In the present study, we examined the direct effects of fluvastatin on proliferation, matrix and growth factor production by rat kidney fibroblasts (NRK-49F cells).. Treatment with fluvastatin reduced proliferation of NRK-49F cells in a dose-dependent manner. The addition of mevalonate or geranylgeranyl pyrophosphate but not farnesyl pyrophosphate to the culture medium almost completely abolished the effect of fluvastatin. Moreover, fluvastatin treatment decreased the expression of activated Rho in NRK-49F cells suggesting that fluvastatin may decrease cell growth through blocking the activation of Rho. The majority of fluvastatin-treated cells were arrested at the G1 phase, associated with down-regulation of cyclin A and up-regulation of cyclin-dependent kinase inhibitor p27kip1, indicating that cell cycle modulation is an important mechanism. Fluvastatin significantly decreased messenger RNA expression of type III collagen and connective tissue growth factor.. Taken together, it is suggested that fluvastatin may prevent tubulointerstitial fibrosis in a variety of progressive renal diseases by inhibiting proliferation of interstitial fibroblasts and their matrix synthesis.

Topics: Acute-Phase Proteins; Animals; Cell Cycle Proteins; Cell Line; Cell Proliferation; Collagen Type III; Connective Tissue Growth Factor; Cyclin A; Cyclin-Dependent Kinase Inhibitor p27; Fatty Acids, Monounsaturated; Fibroblasts; Fibrosis; Fluvastatin; G1 Phase; Immediate-Early Proteins; Indoles; Intercellular Signaling Peptides and Proteins; Kidney; Kidney Tubules; Mevalonic Acid; Nephritis, Interstitial; Polyisoprenyl Phosphates; Rats; Sesquiterpenes; Tumor Suppressor Proteins