The Effects and Mechanism of miR-92a and miR-126 on Myocardial Apoptosis in Mouse Ischemia-Reperfusion Model

Our objective was to explore the effects of miR-92a and miR-126 on myocardial apoptosis in mouse ischemia-reperfusion model and further investigate the underlying mechanisms. Eighteen Kunming mice were selected and randomly divided into sham operation group and ischemia-reperfusion group with nine mice in each group. Cardiac muscle tissue was stained with Evans blue to confirm myocardial infarction and ischemia. Annexin V/PI double staining was used to detect the apoptotic rate of myocardial cells, and terminal-deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) was used to detect the number of apoptotic cells; Western blot was used to detect expression of Caspase 3 to evaluate the apoptosis of mouse myocardial cells; qRT-PCR was used to detect expression of miR-92a and miR-126 in mouse myocardium, and Western blot was used to detect expression of HSP70 in two groups. Evans blue staining results showed that there was a large area of ischemia in myocardium of ischemia-reperfusion mice with marked infarction, suggesting successful establishment of the model. In sham operation group, myocardial cells were mostly normal cells. Annexin V/PI double staining of flow cytometry result showed that the apoptotic rate was 5.9 % in sham operation group and 37.0 % in ischemia-reperfusion group, respectively. Apoptosis detection results showed that apoptotic index (AI) of myocardial cells in ischemia-reperfusion mice was significantly higher than in sham operation group. In addition, qRT-PCR results showed that miR-92a expression in ischemia-reperfusion group was significantly higher than in sham operation group (F = 32.302, P = 0.000), and miR-126 expression in ischemia-reperfusion group was significantly lower than in sham operation group (F = 41.125, P = 0.000). Moreover, HSP70 detected by Western blot showed that HSP expression in ischemia-reperfusion group was significantly lower than in sham operation group. The change of miR-92a was in accordance with AI of myocardial cells. However, the change of miR-126 is in contrary with AI of myocardial cells, which may be related to the HSP70 expression in myocardial cells.