Protective effect of miR-9-5p regulating transient receptor potential melastatin 7 on myocardial ischemia-reperfusion in rats / 解剖学报

ABSTRACT

Objective To investigate the effect of microRNA-9-5p (miR-9-5p) regulating transient receptor potential melastatin 7 (TRPM7) on myocardial ischemia-reperfusion (MIR) in rats. Methods Thirty-two SD rats were divided into sham operation group, model group, miR-9-5p overexpression group and empty vector control group. The MIR model was established by ligation of left coronary artery. The sham operation group was not ligated. miR-9-5p agomir and agomir NC were injected into tail vein 24 hours before model establishment in miR-9-5p overexpression group and empty vector control group. The myocardial injury was observed by HE staining. The expression of miR-9-5p was detected by Real-time PCR. The serum levels of interleukin(IL)-6, tumor necrosis factor alpha(TNF-α), IL-1β, creatine kinase isoenzyme MB (CK-MB), cardiac troponin Ⅰ (cTnI), lactate dehydrogenase (LDH) and the contents of malondialdehyde (MDA) and superoxide dismutase (SOD) in myocardium were measured were measured by ELISA. Cardiomyocyte apoptosis was detected by TUNEL. Double luciferase assay verified the relationship between miR-9-5p and TRPM7. The protein expressions of TRPM7, Bcl-2, Bcl-2 associated X (Bax), phosphorylated nuclear factor kappa-B 65 (p-NF-κB p65) and toll like receptor 4 (TLR4) were detected by Western blotting. Results The expression of miR-9-5p was low in myocardial tissue of rats (P<0.05). Overexpression of miR-9-5p could reduce the expression levels of CK-MB, cTnI and LDH, and improve the degree of myocardial injury. Compared with the model group, the apoptosis rate, Bax protein expression, MDA, IL-6, TNF-α and IL-1β contents in myocardial cells of miR-9-5p overexpression group decreased, while Bcl-2 protein expression and SOD content increased (P<0.05). The result of dual luciferase assay showed that TRPM7 was the target gene of miR-9-5p, and the protein expressions of TRPM7, p-NF-κB p65 and TLR4 in miR-9-5p overexpression group were lower than those in model group (P<0.05). Conclusion MiR-9-5p can inhibit myocardial cell apoptosis, oxidative stress and inflammation induced by myocardial ischemia-reperfusion, and inhibit TLR4/NF-κB pathway by regulating TRPM7.