Expression And Molecular Mechanism Of MicroRNA-15a In Myocardial Ischemia/reperfusion Injury

Objective To study on the the expression of mi R-15 a in H/R model and the effect of micro RNA-15 a regulation on cell injury and apoptosis,and further elucidate the detailed mechanism of mi R-15 a in myocardial ischemia/reperfusion injury.Method Ischemia and reperfusion injury were simulated in vitro with H9c2 rat cardiomyoblasts.MiR-15 a was upregulated and downregulated by lentivirus carrying mi R-15 a and anti-mi R-15 a,respectively.RT-PCR analysis was performed to examine mi R-15 a expression in different groups.Concentrations of lactate dehydrogenase and malonaldehyde in the culture medium and total cell apoptosis was assessed.Luciferase assays were performed to confirm that SMAD7 is a target of mi R-15 a.Expression of SMAD7,cytosolic NF-?B p65 and nuclear NF-?B p65 with mi R-15 a or anti-mi R-15 a transfection were assessed using western blotting.Result MiR-15 a expression was significantly increased compared with the Normoxia group.Under hypoxia/reoxygenation condition,mi R-15 a expression was significantly upregulated and downregulated in the H9c2 cells compared to controls by transfected with mi R-15 a and anti-mi R-15 a,respectively.Overexpression of mi R-15 a increased the lactate dehydrogenase and malonaldehyde levels induced by hypoxia/reoxygenation,whereas anti-mi R-15 a significantly decreased their levels.Annexin V-PE/ 7-AAD dual staining assays showed that mi R-15 a expression increased the apoptosis rate,whereas anti-mi R-15 a expression decreased the apoptosis rate.SMAD7 was confirmed as a target of mi R-15 a.Overexpression of mi R-15 a significantly downregulated SMAD7,whereas anti-mi R-15 a expression upregulated SMAD7.Nuclear NF-?B p65 levels were significantly increased by mi R-15 a ectopic expression and inhibited by anti-mi R-15 a expression.However,the expression of cytosolic NF-?B p65 remained unchanged with mi R-15 a or anti-mi R-15 a transfection.Conclusion MiR-15 a promotes the pathogenesis of myocardial ischemia/reperfusion by regulating the SMAD7-NF-?B p65 pathway.Inhibition of mi R-15 a plays a key role in the pathogenesis and ameliorates cell injury and apoptosis.