非酒精性脂肪肝（NAFLD）是肝硬化和肝癌的主要病因，其发病率在我国急剧上升。申请人前期研究显示在持续营养过剩的条件下，NAFLD病变有显著的传代性恶化效应，并伴随着组蛋白甲基化程度传代性下降。据此申请人提出"在持续营养过剩条件下，组蛋白甲基化修饰积累是引发后代NAFLD传代性恶化的关键"的假说。研究拟采用高脂和正常食物持续喂养的多代小鼠模型，①运用ChIP-seq，在肝脏中研究H3k9me2和H3k9me1调控的传代性变化基因和通路，并探讨其它组蛋白修饰参与NAFLD传代性恶化的可能性；②研究能否通过补充食物中甲基供体来抑制组蛋白甲基化下降，从而改善后代NAFLD的传代性恶化；③研究能否通过改变组蛋白甲基化酶G9a的表达水平来调控后代NAFLD病变进程。本项目将揭示组蛋白甲基化在传代性NAFLD以及相关代谢疾病中的重要生理和病理作用，为预防和治疗该疾病提供理论指导。

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of hepatocelluar carcinoma and hepatic cirrhosis in many counties. The number of newly diagnosed NAFLD patients is dramatically increased in China. Our previous study has demonstrated that there are transgenerational exacerbation of NAFLD and downregulation of histone methylation in the liver of the offspring after continuous high fat diet (HFD) feeding. To address whether this downregulation of histone methylation is the key factor that regulates the transgenerational exacerbation of NAFLD in the offspring, high fat and normal diets will give to mice for three generations as we previously reported. In this model of continuous over-nutrition, ChIP-seq will be performed to investigate the genes or signaling pathways that regulated by H3k9me2 and H3k9me1 in the liver of the offspring. The possible roles of other histone modifications involved in this transgenerational effects will also be investigated. To prevent this transgenerational effects, nutrients enriched in methyl-groups will be given to the continuous HFD-fed mice. The effects of these methyl-group enriched nutrients on histone methylation and pathogenesis of NAFLD in the offspring of continuous over-nutrition will be investigated. To manipulate the expression level of G9a, one of the key histone methyltransferases, transgenic G9a mice and liver specific G9a knock-out mice will be created. The histone methylation levels and pathogenesis of NAFLD will be investigated in the offspring of these new mouse lines after continuous HFD- and normal diet-feeding. This proposal will help us to understand the significant role of histone methylation in the transgenerational accumulation of metabolic diseases, including NAFLD. Through these studies, we may find new therapeutic targets to inhibit these transgenerational effects.