MiR-19家族促进心肌再生修复的调控机制与心梗后心衰治疗的策略研究

成年心肌细胞一直被认为终末分化细胞,退出细胞周期而不能增殖再生。最新研究表明,哺乳动物心肌细胞可以去分化重新回到细胞周期增殖再生,但内源性的增殖能力较弱。因此促进心肌细胞的增殖再生从而改善心脏疾病后心功能成为当前心衰治疗的重要方向。我们之前研究发现miR-17-92基因簇可以促进各时期心肌细胞增殖再生并保护心梗后的心功能。但此基因簇共转录6个成员miR-17,miR-20a,miR-18a,miR-19a,miR-19b,miR-92a,各成员对心肌再生的作用与机制并不清楚。本课题前期实验发现miR-19家族通过PTEN促进心肌细胞的增殖。因此拟通过小鼠遗传模型,腺相关病毒介导和miR-19 mimic输入三种方式过表达miR-19深入研究其促进心肌增殖的分子机制和心梗后再生修复治疗效果。研究结果将揭示miRNA促进心肌增殖修复疾病心脏的新机制并发展基于RNA治疗心力衰竭的新策略。

Cardiomyocytes in adult hearts are considered terminally differentiated that have exited from the cell cycle. Recent studies revealed that mature cardiomyocytes are able to proliferate through de-differentiation and re-entering cell cycle. However the intrinsic renew rate of cardiomyocyte in adult heart is low and is insufficient to reverse cardiomyocyte loss and restore cardiac function under pathophysiological conditions. Therefore, exploring new molecules, which can induce cardiomyocyte proliferation, is very promising for cardiac regeneration and repairing in ischemia-induced cardiac damage. We previously reported that miR-17-92 cluster is required and sufficient for cardiomyocytes proliferation and preserved cardiac function after myocardial infarction. The miR-17-92 cluster have 6 members which are co-transcripted. Our pilot experiments indicated that the members of miR-17-92 cluster, miR-19a/19b in particular, are required for and sufficient to induce cardiomyocyte proliferation in vitro through PTEN. In current study, (1)we will generate miR-19a/19b cardiac specific over-expression knock in mouse. (2) We will test the therapeutic potential of miR-19a/19b mimic in the heart using a mouse myocardial infarction model.(3) In addition, we will engineer a adeno-associated viral vector (AAV) carrying the precursors of hsa-miR-19a and hsa-miR-19b plus upstream and downstream flanking sequences (rAAV-miR-19a/19b) to test the long-term effects of cardiac specific overexpression of miR-19a/19b in heart attack. we will define the molecular mechanism by which miR-19a/19b targets and regulates the cell cycle events when adult cardiomyocyte proliferate. Overall, this study will highlight miRNA as a previously unrecognized class of post-transcriptional regulators for cardiomyocyte proliferation and cardiac regeneration and will develop microRNA therapies for so far untreatable heart attack and heart failure.