MicroRNA-374a protects against myocardial ischemia-reperfusion injury in mice by targeting the MAPK6 pathway

Aims: Clinical treatment strategies for patients with myocardial ischemia typically include coronary artery recanalization to restore myocardial blood supply. However, myocardial reperfusion insult often induces oxidative stress and inflammation, which further leads to apoptosis and necrosis of myocardial cells. Increasing evidence suggests that microRNAs (miRNAs) participate in the pathological and physiological processes associated with myocardial ischemia reperfusion. Main methods: In this study, we established a myocardial H/R H9C2 cell model and a mouse I/R model to detect molecules implicated in myocardial I/R regulation and to determine the underlying signal transduction pathways. Key findings: Herein, we showed that the expression of miR-374a-5p decreased in a myocardial cell model (H9C2 cells) of hypoxia/reoxygenation (H/R) and mouse model of ischemia/reperfusion (I/R). Alternatively, over-expression of miR-374a-5p was found to ameliorate myocardial cell damage within both in vivo and in vitro models of ischemia. Further, mitogen-activated protein kinase 6 (MAPK6) was identified as a direct target of miR-374a-5p. Thus, by targeting MAPK6, miR-374a-5p was found to negatively regulate MAPK6 expression. However, up-regulation of MAPK6 functioned to inhibit the previously observed protective effect of miR-374a-5p in the H9C2 H/R model. Significance: Taken together, our study suggests that miR-374a-5p may have protective effects against cardiac I/R injury in vivo, and H/R injury in vitro, thereby providing novel insights into the molecular mechanisms associated with ischemia/reperfusion injury and a potential novel therapeutic target.