miR‑141 impairs mitochondrial function in cardiomyocytes subjected to hypoxia/reoxygenation by targeting Sirt1 and MFN2

Mitochondrial oxidative stress and dysfunction are major pathogenic features of cardiac injury induced by ischemia/reperfusion (I/R). MicroRNA-141 (miR-141) has been implicated in the mitochondrial dysfunction in cell-based models of oxidant stress. Thus, the main aim of the present study was to systematically assess the role of miR-141 in cardiomyocyte injury induced by simulated I/R. The challenge of HL-1 cardiomyocytes with hypoxia/reoxygenation (H/R) decreased cell viability, which was also associated with an increase in miR-141 expression. The H/R-induced cell injury was mitigated by a miR-141 inhibitor and exacerbated by a miR-141 mimic. Furthermore, H/R induced mitochondrial superoxide production, dysfunction (decreased oxygen utilization and membrane depolarization), as well as ultrastructural damage. These mitochondrial effects were mitigated by a miR-141 inhibitor and intensified by a miR-141 mimic. Luciferase reporter assay, reverse transcription-quantitative PCR, and western blot analyses identified sirtuin-1 (Sirt1) and mitofusin-2 (MFN2) as targets of miR-141. The silencing of Sirt1 reduced the MFN2 cardiomyocyte levels and reversed the alleviating effects of miR-141 inhibitor on mitochondrial function during H/R. Collectively, these findings suggest that miR-141 functions as a causative agent in cardiomyocyte injury induced by I/R, primarily by interfering with two mitochondrial regulatory proteins, Sirt1 and MFN2.