miR-29a promotes myocardial cell apoptosis induced by high glucose through down-regulating IGF-1.

This study was aimed to investigate the role of miR-29a in myocardial cell apoptosis induced by high glucose. Myocardial cells were cultured in normal (5.6 mmol/l) or high glucose medium (30 mmol/l). The apoptotic rate of myocardial cells was evaluated using flow cytometry. The mRNA levels of Bax, Bcl-2, miR-29a, and IGF-1 were determined using real-time quantitative PCR (RT-qPCR). The level of IGF-1 in the culture medium was analyzed using enzyme-linked immunosorbent assay (ELISA). The interaction sites between miR-29a and IGF-1 was analyzed using the the Targetscan program. The regulatory effect of miR-29a on the expression of IGF-1 was investigated using dual luciferase reporter system. The results showed that the expression of miR-29a and the Bax/Bcl-2 ratio in myocardial cells were significantly increased after the cells were cultured in high glucose medium for 72 h, which was consistent with increased apoptosis of myocardial cells. The expression of IGF-1 in myocardial cells was significantly decreased after the cells were cultured in high glucose medium for 72 and 96 h. Targetscan identified a potential binding site on the 3'-UTR of IGF-1 for miR-29a. We also observed that miR-29a mimic and miR-29a inhibitor reduced and increased the expression of IGF-1 in myocardial cells cultured in high glucose medium, respectively. Dual luciferase reporter analysis showed that miR-29a significantly reduced the fluorescence intensity of wild-type psichek2-IGF-1-3'UTR-WT but the fluorescence intensity of mutant psichek2-IGF-1-3'UTR-MT was not significantly affected. In conclusions, the expression of miR-29a in myocardial cells cultured in high glucose medium was significantly increased, which down-regulated IGF-1 and increased myocardial cell apoptosis.