转录辅助抑制因子RIP140在心力衰竭中的转录调控机制研究

Heart failure is the terminal stage of most heart disease including cardiac hypertrophy and myocardial infarction. Energy metabolism abnormality and imbalance of heart have key effects on the pathological process of heart failure. The adjustment of cardiac energy hemostasis is suggested to be a new approach in the therapy of heart failure. Transcriptional cofactors, including coactivators and corepresors, play important role in the maintenance of cardiac energy metabolism via regulating the nuclear receptors and their target gene networks. In this study, we used the rat model of heart failure following LAD ligation and delivered the overexpression of RIP140 protein through adenovirus injection delivery into myocardium to determine the energy state and expression of metabolic regulators on the development of heart failure. We found that myocardial energy reserve index PCr/ATP ratios correlated negatively with the relative expression levels of transcriptional corepressor receptor-interacting protein 140 (RIP140) to coactivator PPARγ coactivator-1α (PGC-1α). What's more, there are many common characteristic, such as common target genes, for these two function-opposing cofactors in the regulation of energy metabolism. However, the exact mechanism of RIP140 in regulating cardiac energy metabolism is still unknown. Can RIP140 regulate target gene transcription via nuclear dependent and/or independent pathways by interacting with and repressing the activity of PGC-1α? What the exact regulation mechanism and functional element of them? To resolve these, we will aim to study the mechanism and target gene of RIP140 in the regulation of cardiac energy metabolism, through CHIP assay, promoter deletion mutation and reporter genes construction. This research may help to elucidate the mechanism of metabolic regulation in the pursuit of significant therapy target in metabolism syndrome subject to heart failure.

心衰是心肌肥大、心梗等大多数心脏疾病的终末阶段。心肌能量代谢障碍及调节失衡是心衰病理过程的核心环节，调节心肌能量代谢是心衰治疗的新策略。转录辅助因子可调节多种与能量代谢有关的基因及转录因子，在维持心脏能量平衡过程中发挥重要作用。我们利用心肌梗死所致心衰模型及过表达RIP140的腺病毒载体心肌室壁多点注射技术发现：转录辅抑制因子RIP140与辅激活因子PGC-1α的相对水平与心脏功能及能量储存关键指标PCr/ATP呈负相关性，而且此两种转录辅助因子调节的靶基因非常相似。但其具体的调节机制尚不清楚，如RIP140是通过与PGC-1α启动子区相互作用抑或直接调节多种转录因子？其转录调节机制及作用域的结构如何？本课题将进一步利用CHIP、启动子缺失突变、报告基因等方法研究与RIP140相互作用且与心肌能量代谢密切相关的靶蛋白并探讨其调控转录机制，为从能量代谢角度探索防治心衰的新靶点提供理论依据。

心肌能量代谢障碍及调节失衡是心衰病理过程的核心环节，从能量代谢角度探索防治心衰的新靶点是心衰研究的新策略。RIP140作为转录辅助因子，可调节多种与能量代谢有关的基因及转录因子，可能对心脏能量平衡的维持发挥重要作用。本研究通过体内、体外实验，探讨RIP140对心肌能量代谢的调控机制以及对心衰疾病进程的影响。在心肌梗死所致大鼠心衰模型上，通过心室室壁注射过表达RIP140腺病毒载体，明确了RIP140对心脏功能、心肌能量代谢和线粒体功能的调控作用。在乳鼠心肌细胞肥大模型上探讨了RIP140对心肌能量代谢的调控机制：（1）揭示了RIP140通过激活NF-κB通路介导心肌炎症反应，从而抑制心肌细胞能量代谢、损伤线粒体功能的调控机制；（2）揭示了RIP140对细胞能量代谢调节器——III类组蛋白去乙酰化酶Sirtuins家族，特别是SIRT3的转录调节作用；（3）探讨了RIP140与PGC-1α是否存在交互调节机制，发现RIP140并非通过直接抑制PGC-1α的表达或转录活性发挥作用，而是竞争拮抗对ERRα等核受体的募集从而调控下游靶基因转录。本课题通过深入研究RIP140调节心肌能量代谢及心衰病理过程的机制，为阐明心肌能量代谢的分子机制开拓了新的思路，也为寻找心衰代谢防治的新靶点提供理论依据。