GW24-e2384 The role of farnesyl pyrophosphate synthase in angiotensin II-induced cardiac fibrosis

Objectives The Rho guanosine triphosphatases (Rho GTPases)family, including RhoA, plays an important part in angiotensin II (Ang II)-mediated cardiac fibrosis. Farnesyl pyrophosphate synthase (FPPS)-catalysed isoprenoid intermediates are important for activation of RhoA. Evidence is accumulated for crucial role of FPPS in the process of cardiac hypertrophy and fibrosis. The present study was designed to investigate the role of FPPS in cardiac fibrosis induced by Ang II. Methods In vivo and in vitro model of cardiac fibrosis were settled by Ang II. FPPS expression was measured by Western blot and qRT-PCR. Cultured neonatal cardiac fibroblasts (NCFs) proliferation was determined by Cell Counting Kit-8 assay and Edu assay. The role of FPPS was both estimated by FPPS inhibitor (zolendronate) and RNA interference (RNAi) against FPPS in NCFs. RhoA activation was evaluated by pull-down assay. Results First, We demonstrated that FPPS expression was elevated both in the in vitro model of NCFs and in the in vivo model of myocardium by Ang II. Then, FPPS inhibition by zolendronate decreased cardiac fibrosis marker gene of collagen I, collagen III and transforming growth factor β1(TGFβ1). Furthermore, the inhibition was reversed with geranylgerananyol (GGOH) and mimicked by Rho inhibitor, suggesting that the anti-fibrotic effect of zolendronate might be via limitation of RhoA geranylgeranylation. Pull-down assay showed that zolendronate reduced active RhoA by Ang II, which was also partially antagonised by GGOH. In addition, FPPS specifically knocking-down prevented expression of collagen I, collagen II and TGF β1, as well as prevented elevated RhoA activity by Ang II compared with non-silencing controls. Conclusions This study reveals FPPS elevation in Ang II-induced cardiac fibrosis model both in vivo and in vitro model. The inhibition and knockdown of FPPS reduces RhoA activation by diminishing geranylgeranylation which prevents Ang II-induced collagen I, collagen III, TGF β1 expression.