环状RNA分子circ-Rictor通过抑制宿主基因Rictor表达调控心肌肥厚的机制研究

As a class of non-coding RNA, circular RNA is recently considered having pivotal function in various biological process and human diseases. In our primary studies, we compared the myocardial transcriptomes from 15 patients with hypertrophic cardiomyopathy and 8 healthy controls. A circular RNA, circ-Rictor, was found to be up-regulated by 6-fold in patients. Circ-Rictor is derived from the gene encoding Rictor, who binds with mTOR protein to form mTOR complex 2 (mTORC2). MTORC2 was involved in the regulation of cardiac remodeling and can prevent the hypertrophic heart from transition to heart failure. We also overexpressed circ-Rictor in cultured neonatal rat cardiomyocyte. Overexpression of circ-Rictor resulted cardiomyocyte hypertrophy with increased cell surface and up-regulated ANP and BNP. At the same time, the expression of its host gene was suppressed, shown by decreased Rictor protein. Thus, we proposed that circ-Riptor can function as a pivotal regulator of cardiac hypertrophy by negatively regulate its host gene Rictor. In order to confirm our hypothesis and reveal the molecular regulation of circ-Rictor in cardiac remodeling, we will 1) overexpress and knockdown circ-Rictor in neonatal rat cardiomyocyte respectively to observe whether the cell is affected with oand without ISO stimulation. 2) The cardiac-specific transgenic mice of circ-Rictor overexpression and knockdown will be generated, respectively. The cardiac structure and function will be monitored, and further histologic and signaling transduction of Rictor will be measured at the time point that cardiac remodeling occurs. Moreover, Cardiac remodeling models will be generated by TAC operation in these mice, the effect of circ-Riptor overexpression and knockdown on cardiac hypertrophy and the transition from hypertrophy to heart failure will be observed. 3) Rictor will be overexpressed in cells and mice with circ-Rictor overexpression, in order to investigate whether forced upregulation of Rictor can antagonize the effect of circ-Rictor. 4) Finally, the interaction pattern of circ-Rictor and Rictor will be determined. Through this study, the function and signal pathways of circ-Rictor in myocardium and cardiac remodeling will be revealed.

环状RNA在心血管疾病中的作用尚不清楚。我们通过分析HCM和对照心肌转录组，发现环状RNA circ-Rictor在肥厚心肌中升高6倍。高表达circ-Rictor诱导心肌细胞肥大，同时导致Rictor表达降低，提示circ-Rictor通过反向抑制Rictor发挥功能。本研究将：1）在心肌细胞中过表达和敲低circ-Rictor，并且建立circ-Rictor的心肌特异转基因和基因敲低小鼠模型，研究circ-Rictor在维持正常心肌结构功能以及在心肌重构和心衰中的调控作用；2）体内和体外高表达Rictor，观察能否拮抗circ-Rictor对心肌肥厚的调控；3）通过发现circ-Rictor与Rictor的直接作用模式，探讨circ-Rictor调控心肌肥厚的分子机制。通过本研究，我们期望能够阐明circ-Rictor在心肌肥厚中的调控作用及机制，为理解心肌重构的发生机理提供新视角。

本课题研究了环状circ-Rictor在心肌肥厚中的调控作用。心肌肥厚常见于各种心血管疾病，是造成心力衰竭的重要原因，是延缓和阻断心力衰竭发生的重要干预节点。环状RNA是一类是一类3’端和5’端相接的闭合式非编码RNA，广泛存在于人体的各种组织器官中，在疾病发生发展中具有重要作用。我们首先解析了肥厚型心肌病患者心肌组织的环状RNA表达改变图谱，完成了相关宿主基因的功能分析。发现环状RNA circ-Rictor在肥厚型心肌病患者中显著上调，过表达circ-Rictor可以导致心肌肥，circ-Rictor会反向抑制宿主基因表达。同时，circ-Rictor在心纤维化模型中同样显著上调，对TGF-β刺激产生正向应答，提示circ-Rictor在心肌肥厚和心肌纤维化中均具有促进作用。本课题共发表研究论文12篇，其中SCI论文1篇，中文论文11篇；参与培养研究生6名；申请发明专利1项。