Inhibition of microRNA-181a-5p Protects H9c2 Cells from Hypoxia-Induced Injury Through Up-Regulating Sirtuin 1 Expression

Abstract

Myocardial infarction (MI), a life-threatening cardiac event, results in extreme damage to the heart muscle. In this study, we were committed to exploring the role and related mechanisms of microRNA-181a-5p (miR-181a-5p) in MIin vitro. Firstly, we established the MIin vitro cell model by subjecting H9c2 cells to hypoxia. We found that miR-181a-5p was significantly increased in hypoxia-induced H9c2 cells. Then, TargetScan and dual luciferase reporter gene assay confirmed the binding sites between Sirtuin 1 (SIRT1) and miR-181a-5p. SIRT1 was significantly reduced in hypoxia-induced H9c2 cells. Next, we explored the effect of miR-181a-5p inhibitor on hypoxiainduced H9c2 cell injury. The findings indicated that miR-181a-5p inhibitor significantly reduced creatine kinase-MB (CK-MB) and cardiac troponin I (cTnI) production enhanced by hypoxia treatment. Moreover, miR-181a-5p inhibitor increased mitochondrial viability in hypoxia-induced H9c2 cells. MTT assay showed that miR-181a-5p inhibitor enhanced hypoxia-induced H9c2 cell viability, and flow cytometry assay indicated that miR-181a-5p inhibitor reduced H9c2 cell apoptosis. ELISA assay indicated that compared with hypoxia treatment group, miR-181a-5p inhibitor decreased the secretion of inflammatory factor such as IL-6, TNF-α and IL-1β . Finally, Western blot assay showed that miR-181a-5p inhibitor decreased the expression of p-p65, indicating the inhibition on NF- κB signaling pathway activation. However, all these effects of miR-181a-5p inhibitor on hypoxia-induced H9c2 cells were reversed by SIRT1-siRNA. Taken together, miR-181a-5p inhibitor protected against hypoxia-induced H9c2 cell injury by targeting SIRT1.