miR-327在心肌缺血再灌注损伤中的作用及分子机制研究

The activities of inflammatory, apoptotic and autophagic responses mediated by intercellular signaling pathways play critical roles in the pathogenesis of myocardial ischemia/reperfusion injury (MIRI).‘RP105-TLR2/4 imbalance’ synergistically regulates the initiations of signaling pathways; meanwhile, Sp1/ARC obstructs the transduction of multiple-detrimental responses. Therefore, it is important to investigate key mediators that selectively modulate upstream molecular and simultaneously regulate downstream signaling transductions. According to the miRNA expression profiles in MIRI and the bioinformatics analysis, we found that up-regulated miR-327 might be one of the key miRNAs involved in MIRI. In the present study, 1) we attempt to investigate the influence and molecular mechanism of miR-327 over-expression and silencing on its potential targets-RP105, Sp1 and ARC; 2) observe that downregulated miR-327 selectively mediate the expressions of TLR2/4, and meanwhile regulate multiple detrimental processes, through which miR-327 significantly ameliorate MIRI. This research might offer prospective strategies that miR-327 act as central mediator in prevention of MIRI via multiple protective manners, and provide novel targets for the treatment of MIRI.

信号通路介导的炎症、凋亡、自噬反应是调节心肌缺血再灌注损伤（MIRI）的关键节点。其中，“RP105-TLR2/4失衡”协同调控上游信号转导，同时Sp1/ARC在下游“阻断”多重损伤效应。因此探寻能够选择性干预上游信号同时影响下游通路转导的关键因子具有重大意义。本课题结合MIRI的miRNAs表达谱芯片和生物信息学分析，选取前期研究证实在MIRI中表达显著升高的miR-327为核心：（1）通过调控miR-327表达，探索其对靶基因RP105、Sp1、ARC及相关信号通路的“多位点”干预作用及分子机制；（2）观察下调miR-327通过负向调控“多位点”靶基因，选择性调节上游TLR2/4表达，并干预介导多重致病环节的关键下游信号分子，从而在整体水平减轻MIRI。通过本项目的成功实施，为以miR-327“多途径”调控为核心的研究思路提供实验依据，为有效防治MIRI提供新靶点。

心肌缺血再灌注损伤（MIRI）是减弱冠心病患者再灌注治疗效果的重要因素，然而目前各种防治措施对再灌注心肌的保护作用有限，其原因可能与干预靶点的作用单一性有关。本课题结合MIRI后miRNAs表达谱芯片和生物信息学分析，选取前期研究证实在MIRI中表达显著升高的miR-327为核心：（1）通过上调或抑制miR-327表达，探索其对靶基因RP105、ARC、FGF10及相关信号通路的“多位点”干预作用；（2）观察miR-327通过负向调控“多位点”靶基因，选择性上调保护基因与下调致病基因，干预介导多重致病环节的上下游关键信号转导，从整体水平探讨上调或抑制miR-327表达对MIRI的影响。目前已取得的研究结果如下：（1）腺病毒成功转染大鼠心肌组织及H9C2心肌细胞；（2）下调miR-327的表达显著促进其靶基因RP105、ARC和FGF10的表达，抑制下游信号分子TLR4、TLR2的表达，活化PI3K/Akt信号通路；（3）下调miR-327可显著改善缺血再灌注诱导的心肌组织损伤及心肌细胞活性；（4）下调miR-327可显著改善缺血再灌注诱导的心肌细胞凋亡、炎症反应和氧化应激。通过本项目的成功实施，可进一步阐明miR-327在MIRI中的作用和分子机制，为临床防治心肌缺血再灌注损伤提供新的实验依据及干预靶点。