Before Apoptosis Protein Bim Modulate Autophagy And Apoptosis In Myocardial Ischemia-reperfusion Injury

Objective:Myocardial ischemia reperfusion(I/R)injury leads to excessive autophagy which promotes apoptosis,pro-apoptotic protein Bim is the intersection of autophagy and apoptosis in dialogue.Our team recently found myocardial cells under hypoxia have increased apoptosis rate accompanied by expression of Bim upregulated.We hypothesized that excessive autophagy occurredunder myocardials I/R injuryand overexpression of Bim promotes apoptosis.To explore the relationship between Bim,autophagy and apoptosis by using autophagy inhibitor intervention.The results are expected to reveal the myocardial I/R injury Bim mediated autophagy and apoptosis in the dialogue mechanism,to provide new ideas for prevention and treatment of myocardial I/R injury.Methods:Cultured myocardial cells,establishing hypoxia / reoxygenation(H/R)model,adding autophagy inhibitor 3-methyladenine 10 mM in reoxygenation(3-MA),20?M(CQ)chloroquine intervention.The experiment was divided into four groups:normal group(control),H/R group,H/R+3-MA group,H/R+CQ group,to explore the relationship between Bim and apoptosis and autophagy.Using tetramethyl azo salt azole(determined by MTT colorimetric method to detect myocardial cell survival rate,spectrophotometric method determination of lactate dehydrogenase(LDH)levels,flow cytometry instrument to detect cell apoptosis rate;Real-time PCR detection of Bim,LC3,Beclin1 mRNA expression level;Western-blot detecting apoptosis related proteins Bim,active caspase 3,CytC and the expression of LC3,Beclin1 protein involved in autophagy.Results:Hypoxia reoxygenation group compared with normal group,LDH and apoptosis rateincreased,cell survival rate decreased;Bim,LC3,Beclin1 mRNA expression increased(p<0.01);hypoxia reoxygenation group Bim,active Caspase3,CytC,LC3,Beclin1 proteinexpression increased.Join the autophagy inhibitor 3-methyladenine,chloroquine treatedwith hypoxia reoxygenation group,drug group LDH and apoptosis rate decreased,cellsurvival rate increased(p<0.01);Bim,Beclin1 mRNA expression decreased;Bim,active caspase3,CytC,Beclin1 protein expression decreased.H/R + 3-MA,H/R + CQ group and hypoxia reoxygenation group contrast,H/R + 3-MA group LC3 mRNA and protein expression decreased(p < 0.01),while group CQ LC3 protein and mRNA expression quantity increased(p < 0.01).Conclusion:Bim is involved in hypoxia reoxygenation on myocardial cell injury,by inhibiting excessive autophagy,Bim expression,reduce cell apoptosis,reduce myocardial ischemia reperfusion injury.Hypoxia leads to excessive autophagy,autophagy induced by excessive cell apoptosis and Bim expression upregulate..Bim may be a bridge between to apoptosis and autophagy.