MicroRNA-137 Negatively Regulates H(2)O(2)-Induced Cardiomyocyte Apoptosis Through CDC42

BACKGROUND: Oxidative stress, inducing cardiomyocyte apoptosis or myocardial ischemia, is the major denominator of many cardiac diseases. In this study, we intended to explore the regulatory function of microRNA-137 (miR-137) in oxidative stress-induced cardiomyocyte apoptosis. MATERIAL/METHODS: Cardiomyocytes were extracted from newborn C57BL/6 mice and cultured in vitro. Apoptosis was induced by H(2)O(2), and evaluated by TUNEL assay. The effect of cardiomyocyte apoptosis on gene expression of miR-137 was evaluated by qRT-PCR. Lentivirus was used to stably down-regulate miR-137, and the subsequent effects of miR-137 down-regulation on cardiomyocyte apoptosis, its targeted gene CDC42, and caspase pathway were evaluated by TUNEL assay, dual-luciferase reporter assay, and Western blot assay, respectively. Finally, CDC42 was down-regulated by siRNA and its effect on miR-137-mediated cardiomyocyte apoptosis protection was examined. RESULTS: H(2)O(2) induced significant apoptosis and up-regulated miR-137 in cardiomyocytes, whereas lentivirus-mediated miR-137 down-regulation protected against apoptosis. CDC42 was the direct target gene of miR-137 and proteins of CDC42, caspase-3, and caspase-9 were all regulated by miR-137 down-regulation in cardiomyocyte apoptosis. SiRNA-mediated CDC42 down-regulation reversed the protection of miR-137 down-regulation against cardiomyocyte apoptosis. CONCLUSIONS: Our work demonstrated miR-137 and CDC42 are critical regulators in cardiomyocyte apoptosis. It may help to identify the molecular targets to prevent myocardial injury in human patients.