Elucidating the role of hepatic mTORC2 as a key regulator of carbohydrate metabolism in non-alcoholic fatty liver disease

项目摘要 非酒精性脂肪肝（NAFLD）目前影响约30%的美国人， 每年约1030亿美元。然而，护理标准仍然是生活方式的改变和肝脏 目前没有FDA批准的治疗方法。NAFLD通常与肥胖相关， 在发达国家和发展中国家。雷帕霉素复合物2（mTORC 2）的哺乳动物靶标正在出现 作为碳水化合物和脂质代谢的中心枢纽，其激活与NAFLD有关， 小鼠这些最近的研究强调了mTORC 2在小鼠高脂饮食中的调节作用， 其中肝脏mTORC 2消融提供了针对高脂肪诱导的肝脏脂肪变性的保护作用。 然而，膳食补充剂，已最归因于非酒精性脂肪肝的上升，在人类是 碳水化合物，特别是果糖。虽然在高脂饮食期间肝脏中mTORC 2消融的保护作用 尽管人们已经研究了高碳水化合物饮食，但它对高碳水化合物饮食的影响却被忽视了。在这里，我将检查 mTORC2保护免受高碳水化合物诱导的肝脂肪变性的能力，如先前所述， 在高脂肪饮食的背景下。从机制上讲，我将研究肝脏mTORC2 调节碳水化合物衍生的乙酰辅酶A的合成和利用，随后促进发病 的NAFLD。我将通过检查两种不同的乙酰辅酶A生产酶来完成这一点：ACLY和ACSS2。 我不仅将研究mTORC2在通过磷酸化调节ACLY和ACSS 2中的作用， 也是首次使用生长素降解决定子系统研究急性环境中的mTORC2丢失， 植物内源性降解标签。随着这项拟议工作的完成，我坚信， 将获得对肝脏信号传导和代谢的更详细和机制的理解， 这些目标最终可用于治疗NAFLD和其他代谢疾病。

Project Summary Non-alcoholic fatty liver disease (NAFLD) currently effects around 30% of Americans and costs the U.S approximately $103 billion annually. However, the standard of care remains lifestyle changes and liver transplantation with currently no FDA approved therapies. NAFLD often correlates with obesity which is rising in both developed and developing nations. Mammalian target of rapamycin complex 2 (mTORC2) is emerging as a central hub for carbohydrate and lipid metabolism, with its activation having been linked to NAFLD in mice. These recent studies have highlighted a role for mTORC2 modulation during high-fat diets in mice, where hepatic mTORC2 ablation provides a protective effect against high-fat induced hepatic steatosis. However, the dietary supplements that have been most attributed to the rise of NAFLD in humans are carbohydrates, specifically fructose. While protective effects of mTORC2 ablation in the liver during high-fat diet have been investigated, its impact on high-carbohydrate diets has been neglected. Here, I will examine the ability for mTORC2 to protect against high-carbohydrate induced hepatic steatosis, as has previously been seen in the context of high-fat diets. Mechanistically, I will investigate the role by which hepatic mTORC2 regulates carbohydrate derived acetyl-CoA synthesis and utilization, subsequently promoting the pathogenesis of NAFLD. I will accomplish this by examining two distinct acetyl-CoA producing enzymes: ACLY and ACSS2. Not only will I investigate mTORC2’s role in regulating both ACLY and ACSS2 through phosphorylation, but also for the first time, investigate mTORC2 loss in an acute setting using an auxin degron system, which is a plant based endogenous degradation tag. With the completion of this proposed work, I strongly believe that a more detailed and mechanistic understanding of hepatic signaling, and metabolism will be obtained, providing targets which could ultimately be used to treat NAFLD and other metabolic diseases.