心肌肥厚中miR-98表达变化的调控机制及其作用的研究

Cardiac hypertrophy is the complication of many heart diseases, which has complex pathogenesis. Abnormality of myocardial energy metabolism is closely related to cardiac hypertrophy and heart failure. Studies have shown that microRNA plays an important role in cardiac development, cardiomyopathy, and metabolic abnormalities. MicroRNA chips and quantitative PCR showed that miR-98 was significantly upregulated in hypertrophic heart. Bioinformatics analysis indicated PGC-1α/β is the potential target of miR-98. And miR-98 was significantly downregulated in cardiac hypertrophy and heart failure，which was accompanied by fatty acid metabolism disorder and mitochondrial damage. Therefore, in this project,we will explore the role of miR-98 in regulating energy metabolism in cardiac hypertrophy and its expression regulation mechanism.Briefly,culture of cardiomyocytes in vitro; overexpression and inhibition of miR-98 in cardiomycytes to investigate the role in myocardial metabolism and its downstream signaling pathway; validation of miR-98 target to PCG-1 3'UTR by using a luciferase reporter; ChIP and epigenetic methods to investigate the regulation mechanism of miR-98; Construction of mouse cardiac hypertrophy model and study of heart function and ventricular remodeling by tail-vein injection of miR-98 antisense oligonucleotides.

心肌肥厚是多种心脏疾病的并发症，发病机制复杂。心肌能量代谢异常是导致心肌病变重要的病理基础，与心肌肥厚和心衰的发生密切相关。研究表明microRNA在心脏发育、心肌病变、代谢异常等起着重要的调控作用。microRNA芯片和定量PCR均发现miR-98在肥厚的心肌组织显著上调。生物信息学分析，心肌能量代谢重要的调节因子PGC-1α/β为miR-98的潜在靶基因，在心肌肥厚及心衰组织中显著下调。PGC-1α/β的下降同时伴随着脂肪酸代谢障碍及线粒体的损伤。因此，我们将探讨miR-98在心肌肥厚能量代谢障碍中的调控作用及其表达的调节机制：分离及培养心肌细胞，过表达及抑制miR-98探讨其对心肌代谢的作用及信号通路；荧光素酶报告验证miR-98的靶基因；ChIP和表观遗传学方法探讨miR-98的表达调节机制；构建小鼠心肌肥厚模型，通过尾静脉注射miR-98反义寡核苷酸观察对心功能、心室重构的影响。

心肌肥厚发病机制复杂,其中心肌能量的代谢异常是导致心肌病变重要的病理基础，与心肌肥厚和心衰的发生密切相关。本研究首先通过芯片筛选并证实心肌肥厚时miR-98的表达显著升高，并证明了miR-98能够靶向调控心肌能量代谢重要的调节因子PGC-1α/β的表达。小鼠TAC术后静脉注射化学修饰的miR-98的模拟物和抑制剂，在心肌肥厚发生代偿期，miR-98抑制葡萄糖的氧化磷酸化，促进糖酵解。在失代偿期，心肌脂肪酸利用相关的基因表达下降，而过表达miR-98加速心肌脂肪酸的摄取和氧化，产生了过量的FAO会造成心肌的损害，抑制心肌内源miR-98，通过能量代谢的调节可以对心脏功能起到保护作用。另外，在肥厚的代偿期，miR-98同时还能够抑制压力超负荷下的心肌肥厚和心肌纤维化。该研究从新的视角揭示肥厚心肌能量代谢紊乱的分子机制，为心肌肥厚的防治提供新思路和新靶点。