转录活化因子4（ATF4)调控酒精性肝病的作用与机制研究

Alcoholic liver disease (ALD) is a major health and economic problem in the western world. The morbidity of ALD in China has risen quickly in recent years, along with the improved living standard and increased alcohol consumption. ALD is closely related to nutrition, living habits and the metabolic homeostasis. At present, its pathogenesis is still largely unknown, and it is lack of effective treatment drugs. Our previous work had shown that activating transcription factor 4 (ATF4) plays a key role in lipid metabolism, energy metabolism, and high-fat-diet(HFD)-induced oxidative stress, inflammation, and liver fibrosis. Based on these results, we hypothesized that ATF4 plays a key role in the development and progression of ALD. To test this possibility, liver specific ATF4 deletion mice and liver specific ATF4 transgenic mice, as well as adenovirus-mediated gene overexpression and knockdown techniques, will be used in current study. We will also investigate the alcoholic induced metabolic phenotypes including of alcoholic fatty liver, alcoholic hepatisis, alcoholic hepatic fibrosis or alcoholic cirrhosis, which is resulting from deletion or overexpression of ATF4 in liver of mice fed on HFD，high carbohydrate diet(HCD) or leucine deficiency diet, and elucidate underlying mechanisms. Identifying the role of ATF4 in the development and progression of ALD is not only important for the understanding of the ALD, but also might provide important hints for the prevention and treatment of ALD. The results of this project will enrich people awareness of ATF4 physiological functions, and provide solid theoretical basis for screening the effective drug target for prevention and treatment of ALD.

酒精性肝病是中国当前面临的严重慢性肝病之一，与营养、生活习惯和机体代谢稳态调控密切相关。目前，其发病机制和药物治疗的研究尚不完善。我们前期研究发现：活化转录因子4（Activating transcription factor 4, ATF4）参与脂质代谢、能量代谢和高脂饮食诱导的氧化应激、炎症及纤维化，降低ATF4表达抵抗酒精性脂肪肝的发生。本项目中，将利用已有的肝脏特异敲除ATF4的基因突变小鼠和肝脏特异过表达ATF4的转基因小鼠的特色资源，结合成熟的酒精性脂肪肝、酒精性肝炎和酒精性肝纤维化的造模和研究技术平台，系统研究ATF4在不同营养条件下（基础条件、高脂饮食、高糖饮食或者氨基酸缺乏饮食）参与酒精性肝病发生发展的作用及分子机理，并探究ATF4作为防治酒精性肝病的药物靶标的潜在应用价值。其成果将丰富人们对ATF4生理功能的认识，并为开发有效的防治酒精性肝病的药物提供坚实的实验基础。

酒精性肝病是中国当前面临的严重慢性肝病之一，与营养、生活习惯和机体代谢稳态调控密切相关。探索酒精性脂肪肝发生发展的分子机制以及靶向治疗分子途径对有效改善这一健康问题具有重要意义。经本项目资助(No. 81471076)，我们利用肝脏特异敲除活化转录因子4（Activating transcription factor 4, ATF4）的基因突变小鼠制备酒精性肝损伤的动物模型，主要开展了如下研究：首次证实肝细胞ATF4敲除小鼠具有抵抗酒精性肝损伤的作用；证实ATF4-TRB3-AMPK轴是酒精性肝损伤发生发展的重要病理机制，是潜在的酒精性脂肪肝的防治药物分子靶点；分子水平证实TRB3与AMPKα直接结合调控AMPK的磷酸化水平参与酒精性肝脏脂质沉积；项目负责人以通讯作者身份在2016年Journal Biological Chemistry上发表题为“Liver-specific Gene Inactivation of the Transcription Factor ATF4 Alleviates Alcoholic Liver Steatosis in Mice”的研究论文，揭示了ATF4-TRB3-AMPK轴作为酒精性脂肪肝致病主要病理机制，可能作为将来治疗酒精性脂肪肝的药物靶标；完成了项目原定主要研究目标。酒精刺激降低机体血清游离氨基酸水平，本项目探索研究发现亮氨酸缺乏激活ATF4-miR212-5p靶向FAS和SCD1抑制肝脏脂质沉积；研究成果发表在2017年Journal of Molecular Endocrinology上。在此基础上，项目负责人所在课题组在郭非凡研究员指导下拓展研究发现了POMC和AgPR 神经元ATF4缺失影响小鼠机体脂质代谢，成果分别发表在2017的国际学术期刊Diabetes上(2篇)。在项目执行期间，项目组成员的研究成果在国际专业学术期刊Diabetes, Autophagy, JBC, Open biology, Journal of Molecular Endocrinology上共发表标注有本项目资助的SCI研究论文9篇，培养博士研究生4名；项目负责人获得上海市自然科学奖三等奖（排名第二位）。达到了项目预期设定的目标。其成果将丰富人们对ATF4生理功能的认识，并为开发有效的防治酒精性肝病的药物提供坚实的实验基础。