This study aims to investigate microRNA-195 (miR-195) expression in myocardial ischaemia–reperfusion (I/R) injury andthe roles of miR-195 in cardiomyocyte apoptosis though targeting Bcl-2. A mouse model of I/R injury was established. MiR-195 expression levels were detected by real-time quantitative PCR (qPCR), and the cardiomyocyte apoptosis was detectedby TUNEL assay. After cardiomyocytes isolated from neonatal rats and transfected with miR-195 mimic or inhibitor, thehypoxia/reoxygenation (H/R) injury model was established. Cardiomyocyte apoptosis and mitochondrial membrane poten-tial were evaluated using flow cytometry. Bcl-2 and Bax mRNA expressions were detected by RT-PCR. Bcl-2, Bax andcytochrome c (Cyt-c) protein levels were determined by Western blot. Caspase-3 and caspase-9 activities were assessed byluciferase assay. Compared with the sham group, miR-195 expression levels and rate of cardiomyocyte apoptosis increasedsignificantly in I/R group (both P<0.05). Compared to H/R + negative control (NC) group, rate of cardiomyocyte apopto-sis increased in H/R + miR-195 mimic group while decreased in H/R + miR-195 inhibitor group (both P <0.05). MiR-195knockdown alleviated the loss of mitochondrial membrane potential (P <0.05). MiR-195 overexpression decreased Bcl-2mRNA and protein expression, increased BaxmRNA and protein expression, Cyt-c protein expression and caspase-3 andcaspase-9 activities (all P<0.05). While, downregulated MiR-195 increased Bcl-2 mRNA and protein expression, decreasedBax mRNA and protein expression, Cyt-c protein expression and caspase-3 and caspase-9 activities (all P <0.05). Ourstudy identified that miR-195 expression was upregulated in myocardial I/R injury, and miR-195 overexpression may promotecardiomyocyte apoptosis by targeting Bcl-2 and inducing mitochondrial apoptotic pathway.
Volume 100, 2021
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