Neddylation对线粒体脂肪酸beta氧化的调控机理研究

Mitochondrial fatty acid beta-oxidation (FAO) disorders are inherited metabolic disorders causing serious pediatric and maternal morbidity and mortality. Neddylation is a ubiquitylation-like pathway that controls cell cycle and proliferation by covalently conjugating NEDD8 to lysines in specific substrate proteins. However, its role in mammalian metabolism remains unexplored. Recently we have found that hepatocyte-specific UBA3 deficiency leads to neonatal death associated with FAO disorder-like abnormalities: fatty changes in the liver, hypoketotic hypoglycemia, hyperammonemia, acidosis, and accumulation of acylcarnitines in the blood. Moreover, neddylation inhibition results in decreased protein levels of ETFA and ETFB, which are essential for FAO. Further exploration suggests that neddylation is active in the mitochondrion and ETFA and ETFB are potential neddylation substrates. This project aims to establish the notion that the neddylation of ETFA and ETFB stabilizes ETF proteins by inhibiting their ubiquitination and degradation, thereby contributing to FAO. These efforts can identify novel function, novel substrates, and novel E3s for neddylation. Furthermore, our findings can provide novel insight into the pathological mechanisms of FAO disorder and guideline for the clinical usage of neddylation inhibitor.

线粒体脂肪酸beta氧化(FAO)障碍是危害很大的遗传病，而其病理机制还不清楚。最近，类泛素化修饰neddylation新底物和相应病理生理功能的鉴定获得了较大进展，但其在FAO中的调控作用与分子机制还是未知的。我们近期发现neddylation E1催化亚基UBA3在肝细胞中的特异缺失导致小鼠在新生期死亡，伴有FAO障碍症状。筛选可能的介导分子发现FAO酶系中的ETFA和ETFB蛋白量受到影响，而且初步数据表明内源ETFA和ETFB蛋白发生neddylation修饰。这些工作基础提示neddylation系统调控线粒体FAO，关键分子机制可能包括直接修饰ETFA和ETFB从而影响其蛋白稳定性。本项目欲对此科研假设进行验证，项目的完成不仅可揭示neddylation的新功能、新底物和新E3，而且可为线粒体FAO障碍疾病的发病机制提供新见解，为neddylation抑制因子临床应用提供指导。

线粒体脂肪酸beta氧化(FAO)障碍是危害很大的遗传病，而其病理机制还不清楚。最近，类泛素化修饰neddylation新底物和相应病理生理功能的鉴定获得了较大进展，但其在FAO中的调控作用与分子机制还是未知的。本项目中，我们发现neddylation E1催化亚基UBA3或者NEDD8在肝细胞中的特异缺失导致小鼠在新生期死亡，伴有FAO障碍。特别是导致戊二酸尿症II型的系统性症状，筛选可能的介导分子发现FAO酶系中的ETFA和ETFB蛋白量受到影响，在成年小鼠中我们发现了类似现象，肝脏特异性阻断neddylation导致小鼠不能耐受饥饿而提前死亡、伴有酮体生成障碍和脂肪肝。进而我们证明线粒体内neddylation很活跃，内源ETFA和ETFB蛋白发生neddylation修饰，抑制其泛素化修饰和降解，从而影响其蛋白稳定性。戊二酸尿症II型患者中存在的部分ETFs突变导致其neddylation减弱、泛素化增强。项目的完成不仅揭示了neddylation的新功能和新底物，而且为线粒体FAO障碍疾病的发病机制提供了新见解，为neddylation抑制因子临床应用提供指导。