MiR-146b protects cardiomyocytes injury in myocardial ischemia/reperfusion by targeting Smad4.

MicroRNAs, a class of small and non-encoding RNAs that transcriptionally or post-transcriptionally modulate the expression of their target genes, have been implicated as critical regulatory molecules in many cardiovascular diseases, including ischemia-/reperfusion-induced cardiac injury. In the present study, we report on the role of miR-146b in myocardial I/R injury and the underlying cardio-protective mechanism. Antagomir-146b was used to explore the effects of miR-146b on cardiac ischemia/reperfusion injury (30 min ischemia followed by 180 min reperfusion). As predicted, miR-146b overexpression significantly reduced the infarct size and cardiomyocytes apoptosis and release of creatine kinase and lactate dehydrogenase. In addition, miR-146b attenuated H9c2 cell apoptosis. Furthermore, Smad4 was predicted and verified as a potential miR-146b target using bioinformatics and luciferase assay. In summary, this study demonstrated that miR-146b plays a critical protective role in cardiac ischemic injury and may provide a new therapeutic approach for the treatment of myocardial I/R injury.