Effect of microRNA-21 on PTEN/AKT/FOXO3a signal transduction pathway

Objective: To investigate the effect of microRNA-21 on cardiomyocyte apoptosis induced by ischemia-reperfusion injury and the role of PTEN/AKT/FOXO3a signaling pathway. Methods: The rat model of ischemia and reperfusion was established. TUNEL assay of myocardial tissue apoptosis indicated that the apoptotic rate of myocardial cells in I/R injury group was significantly higher than that in normal group (P<0.01), suggesting the success of I/R Modeling. After isolation culture, cardiomyocytes were divided into normal group (Sham group), I/R group and I/R plus microRNA-21 group (I/R+miR-21 group). The effect of miR-21 on myocardial cell apoptosis induced by ischemia-reperfusion injury was observed by transfection of miR-21 recombinant lentiviral vector into cardiomyocytes. The expression levels of miR-21 and PTEN mRNA in myocardium were detected by RT-PCR. The expression of PTEN, pPTEN, AKT, pAKTser473, pAKTThr308, pFOX03a, FOX03a and FasL were detected by Western blot. Results: Hoechst33342/PI results showed that the apoptotic rate of cardiomyocytes in I/R group was significantly higher than that in Sham group (P<0.05) and I/R+miR-21 group was significantly lower than that of I/R group (P<0.05). Compared with Sham group, the expression of miR-21 in cardiomyocytes of I/R group was down-regulated (P<0.05), and the expression of miR-21 in I/R+miR-21 group was about 3 times of that in I/R group. The relative expression of PTEN mRNA in I/R group was 2 times that in CM group (P<0.05) and 5 times in I/R+miR-21 group. Western blot showed that the change of PTEN protein was consistent with the expression level of PTEN mRNA. The relative expression of pPTEN, pAKTser473, pAKTThr308, pFOX03a and FasL protein in I/R group was significantly higher than that in Sham group (P<0.05). The relative expression of pPTEN, pAKTser473, pAKTThr308, pFOX03a and FasL protein in I/R+miR-21 group was significantly lower than that in I/R group. Conclusion: PTEN is one of the target genes of miRNA-21 anti-cardiomyocyte apoptosis. MiR-21 can protect cardiomyocyte apoptosis induced by ischemia-reperfusion injury, and its mechanism may be related to PTEN/AKT/FOXO3a signal transduction Pathway mediated.