表达下调的MicroRNA-130a过度激活心肌细胞自噬致心肌梗死后室性心律失常的研究

Recent studies have indicated a enhanced autophagy after myocardial infarction, and the autophagosomes continue to increase during reperfusion, which promotes the reperfusion ventricular arrhythmias by excessive activating Beclin1 and ATG7. It has been widely recognized that MicroRNAs can regulate autophagy in cardiomyocytes, and MicroRNA-130a (miR-130a) expression is significantly decreased after myocardial infarction, and downregulation of Beclin1 and ATG7 by upregulation of miR-130a can inhibit autophagy. Can the excessive activating autophagy result in ventricular arrhythmias after myocardial infarction? Does downregulation of miR-130a induced excessive upregulation of autophagy by Beclin1 and ATG7? Presently，there is no related research at home and abroad. In our study ,we will construct the myocardial infarction model in mice including miR-130a，Beclin 1 and ATG7 knock out mice, and transfect miR-130a in vivo. In addition, we will culture mouse cardiomyocytes and transfect miR-130a in vitro. we will also detect the expression of miR-130a, Beclin1 and ATG7 in individuals with or without ventricular tachyarrhythmias, who have suffered from myocardial infarction. In the research, we clarify the role of miR-130a and autophagy in ventricular arrhythmias after myocardial infarction to provide a novel way for the treatment of ventricular arrhythmias after myocardial infarction.

研究表明，心肌梗死后，自噬作用增强；再灌注时，自噬体数量会进一步增加，并能通过自噬相关基因Beclin1和ATG7过度激活自噬，促进再灌注室性心律失常发生。现已认识，MicroRNAs对细胞自噬具有调节作用；心肌梗死后，MicroRNA-130a（miR-130a）水平下降；表达上调的miR-130a能通过下调Beclin 1和ATG7的表达来抑制自噬。那么，心肌梗死后，过度激活的心肌细胞自噬是否能导致室性心律失常？表达下调的miR-130a是否能通过靶基因Beclin 1和ATG7过度激活心肌细胞自噬？目前国内外尚无相关研究。本项目拟通过构建小鼠（包括miR-130a、Beclin 1和ATG7敲除小鼠）心肌梗死模型进行活体转染、乳鼠心肌细胞转染以及对人体血液和心肌组织的检测，阐明miR-130a、自噬在心肌梗死后室性心律失常中的作用及其机制，为心肌梗死后室性心律失常的治疗开辟新的途径。

心肌梗死（MI）是全球人类死亡的主要原因之一。miRNA和外泌体在生物生理过程中发挥重要调控作用。我们研究发现miR-130a的过表达在统计学上改善了小鼠MI后的心脏功能并减少了心脏纤维化的面积。真核转录组测序和双荧光素酶报告实验结果验证了Tgfbr1是miR-130a的靶基因。miR-130a的抑制提高了心脏成纤维细胞中Col-1、α-SMA和TGFBR1的表达和Smad3的磷酸化水平；然而，这些增加被miR-130a的过表达所抑制。同时，与TGFBR1共转染削弱了miR-130a抑制α-SMA和Col-1表达的能力。这些发现表明，miR-130a通过直接靶向TGFBR1来调节TGF-β/Smad信号，抑制心脏成纤维细胞向心脏肌成纤维细胞的转化，从而发挥抗纤维化作用。但是，我们未发现miR-130a与心肌梗死后室性心律失常有关。于是，我们探索了外泌体与心肌梗死的关系。我们发现，心梗患者血清来源外泌体通过抑制自噬和铁死亡改善心梗后心功能，HUVECs来源外泌体可能通过激活PI3K/AKT通路抑制心肌细胞凋亡，改善小鼠急性心肌梗死后纤维化，促进其心功能恢复。