MiR-31 Downregulation Protects Against Cardiac Ischemia/Reperfusion Injury by Targeting Protein Kinase C Epsilon (PKCε) Directly.

BACKGROUND Various miRNAs have been shown to participate in cardiac ischemia/reperfusion injury (I/R). miR-31 was identified as the most strikingly upregulated miRNA after acute myocardial infarction; therefore, the underlying role and mechanism of miR-31 in cardiac I/R was investigated. METHODS miR-31 expression was detected after cardiac I/R in mice. The cardioprotective effect of miR-31 downregulation was assessed in vitro and in vivo. The functional target gene and its downstream molecule were determined. RESULTS miR-31 expression increased after I/R. miR-31 downregulation increased cell viability and SOD activity and decreased LDH activity and MDA content in vitro. Additionally, miR-31 downregulation alleviated myocardial infarct size in vivo. PKCε was identified as the functional target gene of miR-31, and NFκB was identified as its downstream molecule that was involved in the miR-31-mediated cardioprotective effect. CONCLUSION miR-31 expression increased throughout the cardiac I/R process, and miR-31 downregulation induced a cardioprotective effect via a miR-31/PKCε/NFκB-dependent pathway.