MiR-499 Inhibits Myocardial Apoptosis After Myocardial Infarction In Rats By Targeted Inhibition Of Sox6

ObjectiveTo study the change of miR-499-5p Expression in rat myocardial Infarcted and to investigate the role of miR-499-5p in cardiomyocyte apoptosis after myocardial infarction in rats,then explore related molecular mechanism.MethodsThe rats were randomly divided into 4 group:sham operation group,AMI group,intramyocardial injection of miR-499-5p mimics group(AMI+miR-499-5p mimics),intramyocardial injection of competing negative control sequence group(AMI+scramble-NC).Evans blue and TTC staining were used to measure the area of myocardial infarction.Cardiomyocyte apoptosis was detected by TUNEL staining.Heart function was detected by Vevo 2100;Sox6 mRNA and miR-499-5p expression was detected by qPCR.Sox6,Bax,Bcl-xl protein expression were analyzed by western blot.Dual luciferase reporter gene assay was used to determine whether miR-499-5p target Sox6 3 'non-coding region.Results1.qRT-PCR: miR-499-5p expression in infarcted myocardium was lower thanthat in non-infarcted myocardium.When compared with scramble-NC group,miR-499-5p expression increased in AMI+miR-499-5p group(1.068±0.647vs8.292±1.079,P<0.01).The expression of Sox6 mRNA was higher in AMI group than that in Sham group.Compared to AMI group,the expression of Sox6 mRNA in AMI+miR-499-5p mimics group was lower.2.TTC staining: compared with AMI+scramble-NC group,the infarct size of AMI+miR-499-5p mimics group decreased(0.658±0.113vs0.381±0.121,P=0.02).3.TUNEL staining: compared with Sham group,the apoptosis rate(%)of cardiomyocytes increased in AMI group(60.435±6.004).When compared with scramble-NC and AMI group,apoptosis rate in AMI+miR-499-5p mimics group decreased(35.643±3.923).4.Western blot: in AMI group,the expression of Sox6 and Bax protein increased,while Bcl-xl decreased.Compared with scramble-NC and AMI group,the expression of Sox6 and Bax protein expression decreased and accordly Bcl-xl protein expression increased.5.Cardial echocardiography: the AMI group had a lower EF(%)(29.230±4.379)and FS(%)(17.440±3.595)than Sham group(P<0.05).Compared to scramble-NC and AMI group,EF value of AMI+miR-499-5p mimics group increased(58.200±8.925),and FS value increased(30.310±3.431)(P<0.05).6.Dual luciferase reporter gene assay suggested that miR-499-5p specifically regulates the 3' non-coding sequence of Sox6.Conclusions1.The expression of miR-499-5p in rat infarcted myocardium decreased.2.miR-499-5p inhibited cardiomyocyte apoptosis and improved cardiac function after myocardial infarction,which may be achieved through targeted inhibition of Sox6,further reducing the expression of apro-apoptotic protein Bax and increasing the expression of anti-apoptotic protein Bcl-xl.