WWP2/PTEN调控肝细胞脂质贮积及诱导NAFLD发病的作用及其分子机制

Nonalcoholic fatty liver disease (NAFLD) is an emerging health problem worldwide. However, the exact mechanisms underlying NAFLD are so far poorly understood. To date, several ubiquitin ligases（E3）have been reported regulating lipid metabolism. Owing to previous work, we validated WWP2 as a new candidate for lipid metabolism. We revealed a high expression of WWP2 in NAFLD mouse model and inhibition of WWP2 ameliorates steatosis in HepG2 cell lines, suggesting a molecular rational for NAFLD although the mechanisms are currently unknown. In this research project, by using CRISPR/Cas9 system and recombined lentivirus/adenovirus technology, as well as in vitro/vivo experiments, we try to exam and confirm that WWP2 mediates PTEN degradation to activate PI3K/Akt pathway, regulating FoxO1、PPARγ、SREBP1c、PPARδ and the other key enzymes involved in lipid metabolism，promoting fatty acid uptake and synthesis, inhibiting fatty acid oxidation, resulting in intracellular lipid accumulation, while increased oxidative stress by activation of the inflammatory cytokines such as NFκB, contributing to the onset of hepatitis. The findings of this project will be useful not only the understanding of the pathogenesis of NAFLD but also forms the basis for rational preventive and treatment strategies.

非酒精性脂肪性肝病（NAFLD）是全球性的公共健康问题，发病机制仍未完全明了。近年报道多个泛素连接酶（E3）调控脂质代谢。我们前期研究鉴定出一个新的脂质代谢相关E3连接酶WWP2，其在NAFLD小鼠肝脏高表达、抑制表达可减轻HepG2细胞的脂肪变性，但机制不明。本项目拟在已有基础上，从蛋白及基因水平着手，利用CRISPR/Cas9系统与重组腺/慢病毒技术，从体内和体外水平验证并确定WWP2通过介导PTEN降解，激活PI3K/Akt通路，促进FoxO1、PPARγ、SREBP1c及下游脂质合成酶的表达，促进肝细胞对脂肪酸的摄取与合成，抑制PPARδ及下游脂肪酸氧化酶的表达，减少脂肪酸氧化，导致胞内脂质贮积，同时激活NFκB等炎症因子，引发氧化应激，增加肝细胞损伤，从而在NAFLD发生发展过程中发挥重要作用。本课题的实施，有助于进一步认识NAFLD发病的分子机制、探寻合理的临床防治策略。