[Role of microRNA-1-mediated AMP-activated protein kinase pathway in cardiac fibroblasts induced by high glucose in rats].

OBJECTIVE: To investigate the role of microRNA-1 (miR-1) in cardiac fibroblasts induced by high glucose in rats.

METHODS: The primary fibroblasts were cultured from the apical tissue of 1-3 day-old Sprague-Dawley (SD) rats. The cells which were passaged to generation 3 or 4, were randomly divided into normal glucose+lentivector-vehicle group (CON+Lv-Vehicle group), normal glucose+lentivector-miR-1 group (CON+Lv-miR1 group), high glucose+lentivector-vehicle group (HG+Lv-Vehicle group), high glucose+lentivector-miR-1 group (HG+Lv-miR1 group), high glucose+Lv-Vehicle+inhibitor group (HG+Lv-Vehicle+CC group), and high glucose+lentivector-miR-1+inhibitor group (HG+Lv-miR1+CC group). The myocardial fibroblasts were cultured in the concentration of 5.5 mmol/L glucose (normal glucose) or 25.0 mmol/L (high glucose) DMEM medium. Then lentiviral vector containing miR-1 silent sequence or the same volume of lentiviral vector was inoculated into the cells. The AMP activated protein kinase (AMPK) inhibitor Compound C (20 μmol/L) was added to the medium at 12 hours before sampling in inhibitor groups. The expression of phosphorylation of AMPK (p-AMPK), collagenIandIII, matrix metalloproteinase (MMP-2, MMP-9), and autophagy flux related protein LC3B-II and p62/SQSTM1 were measured by Western Blot.

RESULTS: The purity of rat myocardial fibroblasts in vitro was 97%. Compared with CON+Lv-Vehicle group, there was no significant difference in the expression of p-AMPK in CON+Lv-miR1 group, the expression of p-AMPK in HG+Lv-Vehicle group was significantly decreased (p-AMPK/t-AMPK: 44.72±3.29 vs. 100.00±7.77, P < 0.01). The expression of p-AMPK in HG+Lv-miR1 group was higher than that in HG+Lv-Vehicle group (p-AMPK/t-AMPK: 60.52±5.16 vs. 44.72±3.29, P < 0.05). Compared with HG+Lv-Vehicle group, the expressions of collagen, MMP, LC3B-II and p62/SQSTM1 in HG+Lv-miR1 group were significantly decreased; after the treatment with AMPK inhibitor, the expressions of collagen, MMP, LC3B-II, p62/SQSTM1 were significantly increased (HG+Lv-Vehicle+CC group vs. HG+Lv-Vehicle group: collagen I/β-actin: 158.74±13.21 vs. 100.00±7.64, collagen III/β-actin: 177.38±17.31 vs. 100.00±5.18, MMP-2/β-actin: 130.09±14.31 vs. 100.00±10.47, MMP-9/β-actin: 215.54±20.92 vs. 100.00±11.28, LC3B-II/β-actin: 159.34±13.83 vs. 100.00±6.44, p62/SQSTM1/β-actin: 201.01±24.02 vs. 100.00±8.62; HG+Lv-miR1+CC group vs. HG+Lv-miR1 group: collagen I/β-actin: 108.69±9.93 vs. 80.83±7.24, collagen III/β-actin: 127.68±10.46 vs. 81.56±9.97, MMP-2/β-actin: 106.66±10.21 vs. 74.80±7.43, MMP-9/ β-actin: 145.65±11.56 vs. 74.63±10.55, LC3B-II/β-actin: 150.15±13.28 vs. 22.98±2.87, p62/SQSTM1/β-actin: 130.48±10.74 vs. 49.90±2.27, all P < 0.05).

CONCLUSIONS: miR-1 gene silencing inhibits myocardial fibrosis induced by high glucose, its mechanism may be related to the up-regulation of p-AMPK, which can recover autophagy flux.