Sirt3在白藜芦醇改善肝细胞线粒体功能预防NASH发生发展中的作用及其机制研究

The prevalence of non-alcoholic fatty liver disease (NAFLD) is increasing worldwide. Nonalcoholic steatohepatitis (NASH), a more serious form of NAFLD, can proceed to cirrhosis and even hepatocellular carcinoma,and therapeutic options are limited. However, there are no ideal measurements for prevention and treatment of patients with NASH. Resveratrol, a polyphenol found in plant products, has known anti-oxidant and anti-inflammatory effects, and has been shown to regulate many cellular processes and to display multiple protective and therapeutic effects. Attenuation of inflammatory markers and hepatocellular injury were observed after a 12 week-treatment with RSV in patients with NAFLD. Those suggested that resveratrol benefit patients with NASH. Recent studies show that the mitochondrial deacetylase Sirt3-mediated regulation of mitochondrial respiratory chain is closely related to hepatocellular oxidative injury and has been a key target for NASH intervention. In this work, by using Sirt3 knockout mice and primary cultured hepatic cells along with the assays of quantitative proteomics analysis and RNA interference, we aim to clarify the hypothesis that resveratrol can affect the expression and activity of Sirt3 and improve Sirt3-mediated deacetylation of mitochondrial respiratory chain, thereby enhance mitochondrial respiratory chain activity and inhibit ROS production and hepatocellular oxidative injury. This study has important theoretical and application prospects for NASH prevention and treatment through dietary approaches.

非酒精性脂肪性肝炎（NASH）是一种较严重的非酒精性脂肪性肝病（NAFLD），且尚未发现理想防治措施。白藜芦醇（RES）具有抗氧化、抗炎症等效应，我们发现RES可显著降低NAFLD患者转氨酶活性和炎症因子水平，推测RES可能成为防治NASH的理想植物化学物。肝细胞线粒体功能障碍及氧化应激损伤是NASH发生发展的中心环节，去乙酰化酶Sirt3介导的线粒体功能调节与氧化应激损伤密切相关, Sirt3基因敲出小鼠容易发生NASH，而RES可上调多种细胞Sirt3表达与活性。结合有关RES防治NAFLD的研究进展和我们前期研究结果，提出“RES可能通过上调Sirt3改善线粒体功能、抑制肝细胞氧化应激损伤而有效预防NASH的发生发展”的科学假说。拟通过建立NASH动物模型、NASH细胞模型，围绕肝细胞的线粒体呼吸链功能障碍及氧化应激损伤，深入探讨RES通过Sirt3预防NASH发生发展及其分子机制。

非酒精性脂肪性肝炎（NASH）是一种较严重的非酒精性脂肪性肝病（NAFLD），且尚未发现理想防治措施。肝细胞线粒体功能障碍及氧化应激损伤是NASH发生发展的中心环节，去乙酰化酶Sirt3 介导的线粒体功能调节与氧化应激损伤密切相关。本项目应用NASH 细胞模型和动物模型，研究白藜芦醇（RSV）通过Sirt3改善肝细胞氧化应激与线粒体功能，预防NASH发生发展的可能机制。主要结果有：①白藜芦醇通过PARP1/AMPK信号通路上调Sirt3表达与活性，抑制ROS生成，减轻细胞氧化应激损伤，改善细胞线粒体功能，进而改善肝细胞脂质蓄积；②白藜芦醇能够通过激活PKA/AMPK信号通路上调肝细胞PPARα表达，进而改善脂质代谢和氧化应激稳态，从而减少高脂和棕榈酸诱导的肝细胞脂肪变性；③RSV能够在肝细胞和脂肪细胞中通过Sirt1促进ATF6的去乙酰化和失活化，削弱ATF6对Sirt1的转录抑制作用并上调Sirt1的转录水平，进而抑制脂滴（LDs）标志基因Fsp27的表达，减少LDs肝细胞和脂肪细胞中的蓄积；④二氢杨梅素（DHM）能够通过AMPK信号通路上调肝细胞Sirt3表达与活性，进而通过Sirt3依赖的去乙酰化调节方式促进肝细胞线粒体呼吸功能和抗氧化能力，从而减少高脂诱导的肝脏脂质沉积或肝细胞脂肪变性，预防NASH的发生发展。该研究为应用RSV和DHM等植物化学物防治NASH提供了科学依据。