FAM3A通过调控ATP合酶β亚基的稳定性和活性促进ATP合成分泌的机制研究

近年糖尿病已成为严重威胁国民健康的重大疾病，但其发病机制迄今尚未完全阐明。线粒体是为细胞提供能量的细胞器，糖脂代谢在很大程度上依赖线粒体产生的能量—三磷酸腺苷（ATP），我们的前期工作提示：FAM3A作为一种新线粒体蛋白，能增加肝细胞内外ATP含量，进一步研究表明FAM3A能增加ATP合酶的核心催化亚基β亚基（ATPSβ）的表达，并与ATPSβ相互作用。本研究拟在前期研究的基础上：1）明确FAM3A与ATPSβ在胞浆和线粒体中是否存在相互作用；2）探讨FAM3A通过与ATPSβ相互作用，调控ATPSβ的稳定性和ATP合酶的活性，影响ATP合成分泌及线粒体功能的机制；3）利用FAM3A基因全身和肝脏特异性敲除小鼠，探讨过表达ATPSβ能否部分逆转由于缺失FAM3A基因所引起的肝脏糖脂代谢紊乱、肝脏ATP合成的减少以及对下游信号通路的抑制，以期为糖尿病的治疗提供新思路。

In recent years, the incidence of diabetes was significantly increased, and serious threatened human health, but its pathogenesis is poorly understood. Mitochondria is the organelle that provide energy to cells, glucose and lipid metabolism is largely dependent on ATP produced by mitochondria, our previous study indicated that FAM3A could increase the ATP production of hepatocytes, while activate the PI3K-Akt signaling pathway independent of insulin to improve the high blood glucose and lipid deposits in diabetic mice, but the mechanism of FAM3A in ATP production and secretion is not clear. As a catalytic subunit of ATP synthase, ATP synthase subunit β (ATPSβ) is responsible for ATP synthesis, which can inhibit liver gluconeogenesis by activating downstream signaling pathways in a similar mechanism with FAM3A. Our current pre-experimental studies found that the levels of FAM3A and ATPSβ consistently decreased in the liver of diabetic mice. In global FAM3A knockout mice liver, the expression of ATPSβ mRNA and protein, as well as the content of ATP were significantly decreased. Overexpression of FAM3A increased the protein expression of ATPSβ in HepG2 cells. Additional study found that FAM3A can interact with ATPSβ. Therefore, we proposed a scientific hypothesis: FAM3A promotes the ATP production and secretion by regulating the protein stability of ATPSβ and activity of ATP synthase. Based on our previous findings and preliminary experimental evidence, the current study aimed to: 1) confirm the interaction of FAM3A and ATPSβ in cytoplasm and mitochondria; 2) investigate the mechanism of FAM3A promoting ATP production and secretion by regulating the protein stability of ATPSβ and activity of ATP synthase, as well as the roles of FAM3A regulate mitochondrial function; 3) utilize global FAM3A gene knockout and liver specific FAM3A gene knockout mice to explore if overexpression of ATPSβ could partly rescue the abnormal liver glucose and lipid metabolic disorders, hepatic ATP production decreased and the downstream signaling pathways inhibited by missing FAM3A gene, in order to provide some new ideas for the clinical treatment of diabetes.