MicroRNA-129-5p通过抑制心肌细胞自噬改善心力衰竭大鼠心功能的作用机制研究

MicroRNA-129-5p improves cardiac function of heart failure rat models by inhibiting autophagy of cardiomyocytes

摘要:

目的 探讨miR-129-5p通过抑制心肌细胞自噬改善心力衰竭（HF）大鼠心功能的作用机制。方法 将40只健康雄性Wistar大鼠作为研究对象，并分为空白对照组、模型组、空载病毒组和miR-129-5p组，每组10只。模型组腹腔注射阿霉素溶液复制慢性HF模型；空白对照组腹腔注射等量0.9%生理盐水；空载病毒组、miR-129-5p组分别通过尾静脉注射空载体病毒、miR-129-5p载体复制HF模型。各组大鼠连续给药6周后，采用心脏彩色多普勒超声仪检测大鼠左室射血分数（LVEF）、左室舒张末期内径（LVEDd）和左室收缩末期内径（LVEDs）。实时荧光定量聚合酶链反应检测大鼠心肌组织miR-129-5p表达，HE染色观察心肌组织病理形态，Western blotting检测心肌细胞自噬相关蛋白表达。结果 模型组、空载病毒组EF较空白对照组降低（P <0.05），LVEDd、LVEDs较空白对照组增大（P <0.05）；模型组与空载病毒组EF、LVEDd、LVEDs比较，差异无统计学意义（P >0.05）；miR-129-5p组EF较模型组升高（P <0.05），LVEDd、LVEDs较模型组缩小（P <0.05）。模型组、空载病毒组心肌组织miR-129-5p相对表达量较空白对照组低（P <0.05），miR-129-5p组较模型组高（P <0.05）。模型组和空载病毒组心肌细胞ATG7蛋白相对表达量较空白对照组升高（P <0.05），miR-129-5p组较模型组降低（P <0.05）。模型组LC3Ⅱ/LC3Ⅰ、Beclin-1较空白对照组增加（P <0.05），P62较空白对照组降低（P <0.05）。miR-129-5p组LC3Ⅱ/LC3Ⅰ、Beclin-1较模型组降低（P <0.05），P62较模型组增加（P <0.05）。结论 HF大鼠心肌组织中miR-129-5p表达下调，可能减弱对ATG7的抑制，上调miR-129-5p可能通过抑制心肌细胞过度自噬，从而改善大鼠心功能。

Abstract:

Objective To investigate the mechanism by which microRNA-129-5p inhibits autophagy of cardiomyocytes and improves the cardiac function of heart failure rat models.Methods Forty male Wistar rats were randomly divided into control group, model group, vector group and microRNA-129-5p group, with 10 rats in each group. The rats in the model group were intraperitoneally injected with doxorubicin to establish the heart failure models, and those in the control group were intraperitoneally injected with the same amount of normal saline. The rats in the vector group and microRNA-129-5p group were also modeled and injected with viruses carrying empty vectors and microRNA-129-5p vectors, respectively. After 6 weeks of injection, the left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter (LVEDd) and left ventricular end-systolic diameter (LVEDs) of rats were measured by echocardiography. The expression of microRNA-129-5p was detected by quantitative real-time polymerase chain reaction (qRT-PCR). The pathological morphology of myocardial tissues was observed by HE staining. Western blotting was used to detect the expression of autophagy-related proteins in myocardial tissues.Results Compared with the control group, the LVEF of the model group and that of the vector group were decreased (P < 0.05), while the LVEDd and the LVEDs of the latter groups were increased (P < 0.05). There was no difference in the LVEF, LVEDd, and LVEDs between the model group and the vector group (P >0.05). Compared with the model group, the LVEF of the microRNA-129-5p group was higher (P < 0.05), whereas the LVEDd and the LVEDs of the microRNA-129-5p group were lower (P < 0.05). The expression of microRNA-129-5p was down-regulated in the model group and the vector group, but was up-regulated in the microRNA-129-5p group compared with the control group (P < 0.05). The protein expression of ATG7 in cardiomyocytes was higher in the model group and vector group than in the control group (P < 0.05), while that in the microRNA-129-5p group was lower than that in the model group (P < 0.05). Compared with the control group, the LC3II/LC3I ratio and the expression of Beclin-1 were increased (P < 0.05), and the expression of P62 was decreased in the model group (P < 0.05). In comparison to the model group, the LC3II/LC3I ratio and the expression of Beclin-1 were lower (P < 0.05), and the expression of P62 was higher in the microRNA-129-5p group (P < 0.05).Conclusions The expression of microRNA-129-5p is down-regulated in myocardial tissues of heart failure rat models, which may weaken the inhibition of ATG7. In contrast, upregulation of microRNA-129-5p could improve cardiac function in rats with heart failure by inhibiting excessive autophagy of cardiomyocytes.