miR-808通过调控TGF-β1改善心肌梗死后心肌纤维化的机制

MiR-808 Improves the Mechanism of Myocardial Fibrosis after Myocardial Infarction by Regulating TGF-β1

目的:探究miR-808通过调控TGF-β1改善心肌梗死后的心肌纤维化的机制。方法:70只健康大鼠,随机选取60只通过冠状动脉结扎法构建大鼠心肌梗死模型,为心肌梗死模型组(心梗组,60只),其余10只为对照组(Control组,10只),术后1周,选取20只心梗组大鼠进行重装慢病毒转染分为miR-808前体组(Pre-miR-808,40μmoL/L)和miR-808抑制剂组(anti-miR-808,40μmoL/L);转染后1周,Masson染色观察各组大鼠心肌组织;提取培养大鼠心脏成纤维细胞和细胞总RNA,RT-PCR检测TGF-β1、Furin蛋白和α-SMA的合成水平,观察miR-808通过调控TGF-β1改善心肌梗死后的心肌纤维化的机制。结果:转染后1周,Masson染色心肌组织切片,心梗组心肌梗死区细胞明显减少,边缘区心肌细胞代偿性肥大,大量排列紊乱的结缔组织增生和炎性粒细胞浸润,部分心肌纤维溶解或断裂,大量胶原纤维沉积;miR-808前体侵染心梗组1周后,组织病变有明显改善,心肌细胞增多、胶原纤维沉淀减少;术后1周,RT-PCR结果显示,与Control组比较,心梗组心肌组织miR-808表达降低,而TGF-β1mRNA的表达升高,差异有统计学意义(P<0.05);转染后1周,RT-PCR结果显示,转染miR-808前体能抑制心脏成纤细胞TGF-β1、Furin蛋白和α-SMA的合成水平,而抑制miR-808则能提高TGF-β1、Furin蛋白和α-SMA的合成水平,并且高于空白对照组,差异有统计学意义(P<0.05)。结论:miR-808可通过靶向作用于Furin蛋白和α-SMA的合成水平调控TGF-β1改善心肌梗死后心肌纤维化。

Objective:To explore the mechanism of miR-808 to regulate myocardial fibrosis after myocardial infarction by TGF-β1.Methods:One week after surgery,SD rat models with myocardial infarction were established by coronary artery ligation,and pathological changes of myocardial tissues were observed by Masson staining.One week after surgery,the extraction and culture of rat cardiac fibroblasts,extraction of total RNA from cells,real-time quantitative PCR detection of TGF-β1,Furin protein and alpha-SMA synthesis level.The reloading lentivirus was divided into miR-808 precursor group(Pre-miR-808)and miR-808 inhibitor group(anti-miR-808),which were transfected into rat myocardial tissues and cardiac fibroblast respectively.Results:One week after the operation,the myocardial tissue sections were stained with Masson,and the infarct area cells in the myocardial infarction group were obviously reduced.The compensatory hypertrophy of the cardiomyocytes could be observed in the marginal area.A large number of irregular connective tissue hyperplasia and inflammatory granulocyte infiltration were arranged.Some of the myocardial fibers were dissolved or broken,and a large number of collagen fibrils were deposited.After the infection with miR-808 precursor for 1 week,the pathological change was remarkably improved,while the number of myocardial cells increased,and the deposition of collagen fibers decreased.One week after operation,real time fluorescence quantitative PCR showed that the expression level of miR-808 in myocardial tissue of the myocardial infarction group was lower than that in the blank control group,while the expression level of TGF-β1 mRNA was higher.The difference was significant(P<0.05).The pre transfection of miR-808 could inhibit the synthesis level of TGF-β1,Furin protein and alpha-SMA in cardiac fibroblast,while inhibition of miR-808 could improve the synthesis level of TGF-β1,Furin protein and alpha-SMA,more than that in the blank control group,and the difference was significant(P<0.05).Conclusion:miR-808 can regulate TGF-β1 by improving the synthesis level of Furin protein and alpha-SMA,and improve myocardial fibrosis after myocardial infarction.