Experimental Study Of The Relationship Between MiR-375 And Ejection Fraction Preserved Heart Failure

一.Background and purposeHeart failure(HF)refers to the pathological condition that the heart can not satisfy the hemodynamics of the body.It is a common clinical syndrome leading to higher mortality.According to the data of the WHO,more than 17 million and 500 thousand people die of HF each year,account for 30% of all died person.HFp EF,also known as diastolic heart failure,accounts for more than 50% of the total HF patients,still have no effective treatment.Early diagnosis is difficult,mainly manifested as myocardial hypertrophy,myocardial fibrosis and diastolic dysfunction.Cardiac hypertrophy significantly increases the risk of HFp EF.Myocardial hypertrophy is a compensatory pathological remodeling process induced by myocardial pressure,including long-term hypertension,myocardial injury and valvular disease.Cardiac hypertrophy is the main pathophysiological response induced by cardiac hemodynamic overload.Early manifestation is diastolic dysfunction,later may develop into cardiac pathological remodeling and systolic heart failure.In recent years,the role of mi RNA in the development of cardiac hypertrophy has been extensively studied.mi RNA is a highly conserved non coding RNA molecule,about 22 nucleotides and mi RNA promotes its degradation or translation inhibition by combining with the 3’untranslated region(3’UTR)of target m RNA,playing an important role in post transcriptional gene regulation.mi RNA is a regulator of cardiovascular system in many aspects such as cardiovascular development,arrhythmia,atherosclerosis,myocardial hypertrophy,myocardial infarction and heart failure.However,the mechanism of mi RNA is not yet clear in cardiac hypertrophy.Studies have shown that mi R-375 plays an important role in ischemic cardiomyopathy,mi R-375 is related to myocardial infarction in mice.However,there has no research shown that mi R-375 plays an important role in cardiac hypertrophy and HFp EF.By screening downstream target genes of mi R-375,it has been proved that PDK1 is a predictive target of mi R-375 in bone marrow progenitor cells.Therefore,we selected the TGF-β /Smads pathway related to myocardial hypertrophy and fibrosis,and selected the upstream protein PDK1 as the upstream protein.In this study,we established TAC mice model,and study whether TAC can simulate the occurrence and development of myocardial hypertrophy in the early stage of HFp EF.We also studied the expression of mi R-375 in TAC mouse model and its relationship with TGF-β /Smads,to provide basic theory for the prevention and treatment for HFp EF.二.Method1.Divide 24 male C57BL/6 mice into 4 groups:sham1,sham2,TAC1,TAC2.2.Recorded the weight changes of the mice before and after operation;Echocardiography and hemodynamic were operated.3.Western-blotting and RT-PCR were carried out.三.Result1.General condition: The weight in TAC2 was statistically significant(P<0.05)compared with before operation.2.Cardiac color Doppler ultrasound : The IVSd and LVPWd in TAC1 and TAC2 were significantly thickened than those in the sham group at the same age,IVRT and EDT were significantly longer than those in the sham group at the same age(P<0.05).E/A decreased significantly in TAC1 and TAC2 compared with no operation(P<0.05).3.Hemodynamic: LVEDP and Tau in mice at TAC2 were significantly higher than those in sham2(P<0.05);-dp/dt Max decreased significantly in TAC2 compared with that in the sham2;Tau was significantly longer in TAC2 than in TAC1(P<0.05);after 8 weeks of TAC,-dp/dt Max was significantly decreased significantly in TAC2 than that in TAC1(P<0.05).4.Western-blotting : PDK1 in TAC was lower than that in sham at the same age(P<0.05);TGFβ1 、smad2/3 and β-MHC in TAC both increased compared with that in sham at the same age(P<0.05).5.RT-PCR :(1)PDK1 and mi R-375-3p gene in TAC was both significantly lower than that in sham(P<0.05).四.ConclusionTAC mouse after 8-week showed obvious diastolic function,and the expression of cardiac hypertrophy pathway protein and factor increased significantly,indicating that TAC can be used to simulate and study HFp EF.It was found that the expression level of PDK1 and mir-375-3p in mice decreased in TAC after 8 weeks compared with in sham,thus predicted that mi R-375-3p was a protective gene for cardiac hypertrophy.PDK1 is the target gene of mir-375-3p acting on cardiac hypertrophy,which lays the foundation for further experiments.