ERK1/2 Signaling Pathway Mediates PDGF-CC Induced Rat Cardiac Fibroblasts Proliferation And Collagen Synthesis

Background and Objective: Cardiac fibrosis is a pathological change on cardiac fibroblasts that proliferate excessively and synthesize large amounts of collagen in myocardium.It is associated closely with coronary heart disease,hypertension,dilated cardiomyopathy,viral myocarditis and other cardiovascular diseases.Cardiac fibrosis is a common manifestation of many heart disease at the end stage.In clinical,the coronary heart disease with severe coronary artery stenosis can lead to persistent or recurrent myocardial ischemia,get cardiac fibrosis and gradually develope into heart failure that is called chronic ischemic cardiomyopathy.That ACEI or ARB drugs can inhibit the prognosis of heart failure by inhibiting renin-angiotensin-aldosterone system(RAAS)may be related to the inhibition of cardiac fibrosis.The pathogenesis of cardiac fibrosis is very complex.There are cell growth factors,oxidative stress,inflammatory factors and vascular endothelial dysfunction and other factors that are involved in the development of cardiac fibrosis beside RAAS.However,the literatures reported in cardiac fibrosis about the cell growth factor are not in-depth discussion.Cardiac fibroblasts are the main cells involved in cardiac fibrosis,and platelet-derived growth factor(PDGF)is an important cell mitogenic factor that stimulates specific cell division and proliferation.In this study,we investigated the effect of exogenous PDGF-CC on rat cardiac fibroblasts and the possible signal transduction chain-ERK1 / 2 pathway in cultured rat cardiac fibroblasts in vitro.ERK1/2 signaling pathway may be related to the mechanism of cardiac fibrosis.Methods: The cardiac fibroblasts(CFs)were isolated and purified from cardiac tissues of 1-3-days old SD rats by differential time attachment,then divided randomly into following 3 groups: control group(CON),PDGF-CC group(P)and group of PDGF-CC+ERK1/2 inhibitors was U0126(PU).MTT assay was used to detect the proliferation of cardiac fibroblasts.The mRNA expression levels of PDGFR-?,PDGFR-?,ERK1,ERK2,collagen type I and collagen type ? were detected by real-time fluorescent quantitative PCR(qRT-PCR).The protein expressions of phosphorylated PDGFR-?(p-PDGFR-?),ERK1 / 2,p-ERK1 / 2,collagen type I and collagen type ? were detected by Western blotting.Results:(1)MTT showed that the number of cells in P group was significantly higher than that in CON group(P<0.01),while the number of cells in PU group was significantly lower than that in P group(P<0.01).(2)qRT-PCR showed that the mRNA expressions of PDGFR-?(PDGF receptor-?),ERK1,ERK2,collagen type I and type III(Col?,Col ?)were significantly higher than CON group(P<0.001),PDGFR-? mRNA expression showed no significant difference between P and CON group,and that PDGFR-??ERK1?ERK2 ?Col?and Col ? in PU group was markedly reduced as compared to P group(P<0.01).(3)Western blot showed that the protein expressions of phosphorylatedPDGFR-?(p-PDGFR-?),ERK1/2,p-ERK1/2,Col I and Col III were significantly higher than that in CON group(P<0.001),and those expressions were significantly decreased in the PU group compared with P group(P<0.001).Conclusions: PDGF-CC can induce the proliferation of cardiac fibroblasts and promote collagen synthesis;PDGF-CC mainly activates of ERK1 / 2 pathway by binding PDGFR-?,PDGFR-?/ ERK1 / 2 signal pathway is involved in cardiac fibrosis;U0126 inhibits ERK1 / 2 pathway and reduces the effect of cardiac fibrosis,it may play a role in anti-cardiac fibrosis.