PPARα/γ共调控FABP4影响心肌能量代谢对房颤发生发展的影响及机制研究

Atrial fibrillation (AF) has become an important social problem in ageing countries, yet the pathogenesis of AF has not been fully elucidated. In our preliminary study, we identified 517 energy metabolism related proteins in the auricle of AF patients and found that the expression of fatty acid binding protein 4 (FABP4), the key molecular of fatty acid metabolism, was down-regulated in the atrial tissue of AF patients. The overexpression of FABP4 could enhance the transportation of fatty acid and promote energy supply in cardiac myocyte, and FABP4 could be regulated by PPARα/γ. Thus, we suppose that FABP4 regulated by PPARα/γ can affect the balance of myocardial fatty acid transportation and energy metabolism, and influence the development of AF. As the common agonist of PPARα/γ, omega-3 fish oil may promote myocardial energy supply and inhibit the development of AF by activating FABP4 expression. In this project, we will construct canine atrial fibrillation model and primary cardiac myocyte to confirm our hypothesis through molecular techniques like recombined adenovirus/lentiviral transfection, chromatin immunoprecipitation and electrophoretic mobility shift assay. This project is likely to illustrate the influence of FABP4 in the abnormal fatty acid energy metabolism during AF and molecular mechanisms of PPARα/γ on regulating FABP4，and then reveal the new mechanisms of omega-3 fish oil in inhibiting AF, which may contribute to new strategies and therapeutic targets for AF prevention and treatment.

心房颤动（房颤）已成为老龄化大国重要社会问题，其发病机制未完全阐明。我们前期鉴定了房颤患者心肌中差异表达的蛋白质，发现脂肪酸转运的关键分子脂肪酸结合蛋白4（FABP4）在房颤患者中表达降低。已知过表达FABP4可增强脂肪酸转运与心肌能量供给，而PPARα/γ可转录调控FABP4表达水平。据此我们科学假说：PPARα/γ共同调节FABP4，影响心肌脂肪酸运输平衡和能量代谢，调节房颤的发生发展；Omega-3鱼油作为PPARα/γ的共同激动剂，可通过激活FABP4改善心肌能量供给，抑制房颤发生。本项目拟在犬房颤模型和原代心肌细胞水平上，利用重组腺病毒/慢病毒转染、染色质免疫共沉淀和凝胶迁移率电泳等技术，阐明FABP4在调控房颤脂肪酸能量代谢异常中的作用，证实PPARα/γ共调控FABP4的具体机制，从而揭示Omega-3 鱼油抑制房颤发生的新机制，为房颤防治提供新的思路和靶点。

本研究通过建立犬急性/慢性房颤模型，运用Omega-3 鱼油、二甲双胍、低迷走刺激等干预方式，探索出相关干预情况下房颤时的能量代谢、脂肪酸代谢、内质网应激状态和房颤的发生发展机制，并进一步拓展研究层面，扩大房颤患者临床样本量，深度分析房颤状态下的翻译后修饰蛋白质组学改变。发现：(1) 犬急性房颤时：房颤使心肌能量代谢状态受损，心肌内能量代谢储备下降，而ATP分解代谢供能受阻，FABP4和脂质沉积增加，而二甲双胍和迷走神经刺激改善急性房颤下的心肌高能量磷酸盐紊乱水平和比例。进一步研究提示，二甲双胍能通过AMPK/PPAR-α/VLCAD通路调节心房脂肪酸代谢，改善房颤的诱发阈值；(2) 犬慢性房颤时：服用Omega-3 鱼油可以改善心房电重塑和房颤易感性、改善内质网应激的反应和心房炎症和Ca2+转运、减少心房肌细胞的纤维化和凋亡。(3) 房颤的翻译后修饰研究：我们扩大收集房颤患者心耳组织标本，采用二甲基标记、修饰亲和富集、高效液相色谱-质谱串联分析测定甲基化、乙酰化及琥珀酰化蛋白质组，分析房颤相关翻译后修饰蛋白质组学差异与关联。获得目前最全面的瓣膜病房颤患者的乙酰化、琥珀酰化蛋白质组差异表达谱。这些结果对于房颤的后期研究提供了有针对性的全面的视野。