MicroRNA-497 promotes proliferation and inhibits apoptosis of cardiomyocytes through the downregulation of Mfn2 in a mouse model of myocardial ischemia-reperfusion injury.

INTRODUCTION: Myocardial ischemia-reperfusion (I/R) injury affects millions of people worldwide and has a very high mortality rate. Since microRNA-497 (miR-497) has been found to be related with cardiomyocyte apoptosis, this study aimed to explore the effect of miR-497 by targeting Mfn2 in a mouse model of myocardial ischemia-reperfusion (I/R) injury.

MATERIALS: BALB/c mice were modeled with I/R and some were injected with miR-497 agomir before I/R to observe whether miR-497 alleviates the injury that occurs as a result of I/R. Bioinformatics website and dual-luciferase reporter gene assay were employed in order to detect the relations between miR-497 and Mfn2 gene. Next, cells were extracted to be transfected with different mimic, inhibitor and siRNAs to further explore how miR-497 acts to I/R. Western blot analysis and reverse transcription quantitative polymerase chain reaction (RT-qPCR) were conducted to measure expressions of miR-497, Mfn2, Fas, Bcl-2, Bax and Caspase-3 in myocardial tissues and cardiomyocytes after transfection. CCK-8 assay and flow cytometry were used to determine proliferation, cell cycle distribution and apoptosis of cardiomyocytes in each group after transfection.

RESULTS: Mice with I/R had myocardial dysfunction but before the injection with miR-497 agomir, the impairment was alleviated. Mfn2 was verified as the target gene of miR-497. The inhibition of miR-497 in turn inhibits Mfn2 expressione and cardiomyocyte apoptosis. The overexpression of miR-497 and Mfn2 gene silencing can lead to the promotion of proliferation capability of mice cardiomyocytes in vitro. Overexpressed miR-497 and Mfn2 gene silencing can also facilitate cell cycle entry and inhibit the apoptosis cardiomyocytes of mice in vitro.

CONCLUSION: The present study provided strong evidence that miR-497 promotes proliferation and inhibits apoptosis of cardiomyocytes by downregulating the expression of Mfn2 in a mouse model of myocardial I/R injury.