SIRT3调控VLCAD乙酰化修饰在脂肪酸代谢异常介导房颤的机制研究

心肌能量代谢失衡是心房颤动（房颤）发生机制之一。我们前期研究发现脂肪酸β氧化限速酶超长链脂酰辅酶A脱氢酶（VLCAD）在房颤患者心肌中表达异常，其乙酰化水平显著上调；已知脂肪酸氧化为心肌最重要供能途径，而乙酰化修饰显著影响蛋白质活性，且沉默信息调节因子3（SIRT3）是调控线粒体蛋白乙酰化修饰的关键因子。据此我们科学假说：VLCAD受乙酰化修饰调控，通过差异性表达调节心肌脂肪酸代谢与心肌供能影响房颤的发生发展；而VLCAD乙酰化程度受SIRT3调控。本研究拟构建VLCAD野生型/乙酰化位点突变型病毒及SIRT3过表达/低表达病毒，在犬房颤模型和原代心肌细胞上研究：①VLCAD的表达及乙酰化修饰对脂肪酸代谢及房颤的影响，②房颤时VLCAD乙酰化调节位点及SIRT3对其乙酰化水平的影响，以期阐明SIRT3调控VLCAD乙酰化修饰影响房颤心肌能量代谢受损的机制，为防治房颤寻找新的干预靶点。

Disordered myocardial energy metabolism is a critical mechanism of the incidence of atrial fibrillation (AF). Our preliminary study presented that the very long-chain specific acyl-CoA dehydrogenase (VLCAD), one rate-limiting enzyme in fatty acid oxidation, was differently expressed in atrial tissues of AF patients, and the level of VLCAD acetylation was also significantly increased. Fatty acid oxidation is known as the most important energy source for myocardial cells. It has also been identified that acetylation could affect the biological activity of proteins and silent information regulator of transcription 3 (SIRT3) plays a key role in mitochondrial proteins acetylation. Thus, we suppose that differential expression of VLCAD, whose activity is influenced by acetylation, could affect the incidence and development of AF through regulating myocardial fatty acid metabolism and energy production, and VLCAD acetylation could be controlled by SIRT3. In the present project, we will construct wild-type and acetylation-mutated VLCAD viruses, SIRT3 gene overexpression and lentiviral vector to investigate (1) the effect of differential expression and acetylation of VLCAD on fatty acid metabolism and AF, and (2) the regulatory site of VLCAD acetylation and the effect of SIRT3 on the acetylation level of VLCAD during AF in both canine atrial fibrillation model and the primary myocardial cells. Our project is likely to illustrate the influence of VLCAD acetylation on regulating energy metabolism during AF, and the effect of SIRT3 on VLCAD acetylation, which may provide new targets for the prevention and treatment of AF.