geranylgeranyl-pyrophosphate and Cardiomegaly

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

Farnesyl pyrophosphate synthase (FPPS) is a key enzyme in the mevalonate pathway. In our previous study, we found that inhibition of FPPS attenuates cardiac hypertrophy in spontaneously hypertensive rats (SHRs) and prevents angiotensin (Ang) II-induced hypertrophy in cardiomyocytes. Here, we further investigate the role of FPPS in cardiac hypertrophy and heart failure (HF) using a transgenic (Tg) model, and its mechanisms.. Tg mice with cardiac-specific expression of FPPS were studied as an experimental model. The results showed that Tg mice with overexpression of FPPS exhibited cardiac hypertrophy, fibrosis, and HF, as well as increased synthesis of farnesyl pyrophosphate (FPP) and geranylgeranyl pyrophosphate in heart tissue. These pathological changes were associated with the activation of RhoA and other known kinases in the hypertrophic signalling pathway, such as extracellular signal-related kinases 1/2 and p38. Adenoviral infection of FPPS in cultured neonatal cardiomyocytes induced a hypertrophic response characterized by an increased cell size and an increased extent of sarcomeric organization, as well as an increased activation profile of small GTPases and downstream protein kinases concordant with those seen in vivo. Further investigation showed a marked increase of FPPS protein levels in hypertrophic ventricles of patients with valvular heart disease.. Taken together, these results suggest that FPPS may function as a potent regulator in myocardial remodelling. The FPPS-regulated signalling pathway is relevant to the pathological changes in cardiac hypertrophy and HF.

Topics: Adenoviridae; Animals; Cardiomegaly; Cells, Cultured; Disease Models, Animal; Female; Gene Expression; Geranyltranstransferase; Heart Failure; Heart Valve Diseases; Humans; In Vitro Techniques; Male; MAP Kinase Signaling System; Mice; Mice, Inbred C57BL; Mice, Inbred CBA; Mice, Transgenic; Myocardium; Myocytes, Cardiac; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Polyisoprenyl Phosphates; rhoA GTP-Binding Protein; Signal Transduction; Ventricular Dysfunction, Left