miR-361-3p mitigates hypoxia-induced cardiomyocyte injury via targeting apoptosis initiators caspase-2/-8/-9.

Acute myocardial infarction (AMI) is an ischemic heart disease with high mortality. AMI-induced hypoxia will trigger serious myocardial injury, such as cardiomyocyte apoptosis. miRNAs have been reported to be involved in the development of AMI. Our previous study revealed that hypoxia regulates the miRNAome of rat cardiomyoblast cells (H9c2), including many known "hypoxamiRs." This study aimed to investigate the potential function of miR-361-3p in the hypoxic response of cardiomyocytes. H9c2 cells were cultured in hypoxic condition and rat AMI model was established by ligating the coronary artery. Cell apoptosis and miR-361-3p expression were measured in hypoxia-exposed H9c2 cell and myocardium of AMI rat. Gain- and loss-of-function analyses in vitro were performed to assess the effect of miR-361-3p in hypoxia-induced cardiomyocyte injury. Hypoxia induced notable changes in cell morphology, triggered cell apoptosis, increased cell membrane damage, and meanwhile decreased miR-361-3p expression in a time-dependent manner. AMI induced cell apoptosis in rat myocardium accompanied by downregulation of miR-361-3p. miR-361-3p overexpression markedly reduced hypoxia-induced cardiomyocyte injury; however, its downregulation had an opposite effect. Functionally, miR-361-3p mitigated hypoxia injury by inhibiting apoptosis via targeting apoptosis initiators caspase-2/-8/-9. This study revealed that miR-361-3p has a cardioprotective effect on hypoxia-induced cardiomyocyte injury, suggesting it may be a novel therapeutic target for hypoxia-related cardiac diseases.