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目的探讨miR-148b参与大鼠心肌梗死后心脏纤维化的作用及可能机制。方法采用结扎大鼠冠状动脉左前降支方法制作大鼠心肌梗死模型,RT-PCR法评价大鼠心脏miR-148b表达水平;应用生物信息学方法预测miR-148b靶基因;采用Western blot方法评价大鼠心脏同源性磷酸酶-张力蛋白(phosphatase and tensin homologue,PTEN)及α-平滑肌蛋白(α-smooth muscle actin,α-SMA)蛋白表达水平;四甲基偶氮唑盐比色(MTT)法检测心脏成纤维细胞增殖能力;应用天狼猩红染色评价心脏纤维化病理改变。结果大鼠心肌梗死组,梗死周边区纤维化程度显著增加,miR-148b表达显著上调(P<0.01);miR-148b与预测靶基因PTEN mRNA有结合位点;大鼠心肌梗死组,梗死周边区PTEN表达显著下调(P<0.01);在心脏成纤维细胞中过表达miR-148b,PTEN的蛋白表达水平显著下调(P<0.01),α-SMA蛋白表达水平显著上调(P<0.01),细胞增殖能力显著增强(P<0.05);在Ang II诱导心肌纤维化细胞模型中,抑制miR-148b,PTEN蛋白表达水平显著上调(P<0.05),α-SMA蛋白表达水平显著下调(P<0.01),心脏成纤维细胞增殖显著减少(P<0.01)。结论 miR-148b通过PTEN参与心肌梗死后心脏纤维化作用。
Objective To investigate the role of miR-148b in cardiac fibrosis after myocardial infarction in rats and its possible mechanism. Methods The model of myocardial infarction was established by ligating left anterior descending coronary artery in rats. The expression of miR-148b in rat heart was evaluated by RT-PCR. The target gene of miR-148b was predicted by bioinformatics method. The expression of PTEN and α-SMA in mouse heart tissue were detected by MTT assay. Method to detect the proliferation of cardiac fibroblasts; assessment of pathological changes of cardiac fibrosis using Sirius red staining. Results The expression of miR-148b was significantly increased (P <0.01) in the myocardial infarction group and the peripheral area of the infarct, and the binding site of miR-148b and the target gene PTEN mRNA were detected. The myocardial infarction group, (P <0.01). The overexpression of miR-148b in cardiac fibroblasts significantly down-regulated the expression of PTEN protein and the expression of α-SMA protein (P <0.01) (P <0.05). The expression of PTEN protein was significantly upregulated (P <0.05) and α-SMA protein expression was significantly down-regulated in Ang II-induced myocardial fibrosis cells model (P < 0.01). The proliferation of cardiac fibroblasts was significantly reduced (P <0.01). Conclusion miR-148b is involved in cardiac fibrosis after PTEN via PTEN.