NAFLD患者的肝脏胰岛素抵抗增加心血管疾病、2型糖尿病风险，并推动肝脏病变进展。新近发现肥胖、高脂饮食等可改变DNA甲基化推动人群肝脏胰岛素抵抗和NAFLD风险逐代累积增加，且目前对此并无有效应对措施。叶酸是机体甲基化的主要供体。我们前期研究发现人体血清叶酸水平与肝脏脂肪样变、胰岛素抵抗负相关，且动物和细胞实验初步发现叶酸可能通过调控细胞内衔接蛋白PDLIM5的DNA甲基化，下调PKCε表达，活化肝脏胰岛素信号通路。但是，尚不清楚这一机制改善肝脏胰岛素抵抗的重要性和可遗传性。因此，本项目拟进一步1)测定人体不同程度脂肪肝组织Pdlim5表达及其甲基化；2)构建Pdlim5敲减动物和细胞模型，探索叶酸调控Pdlim5启动子甲基化介导肝脏胰岛素抵抗改善的重要性；3)自然受孕和IVF-ET方法获得小鼠子代，探索叶酸调控基因表观遗传对子代影响。从而揭示叶酸改善肝脏胰岛素抵抗的机制和传代遗传效应。

Hepatic insulin resistance in patients with non-alcoholic fatty liver disease (NAFLD) could increase risk of developing both type 2 diabetes and cardiovascular disease, and promote the progression of NASH, liver cirrhosis and hepatocarcinoma. Recent studies have shown that metabolic risk factors, such as obesity, high fat diet, et al., can lead to increasing susceptibility to hepatic insulin resistance and NAFLD by transgenerationally altering the DNA methylation in liver, however, there is still a lack of effective measures to intervene with the epigenetic trends and control the current increasing NAFLD prevalence. Folic acid, also called vitamin B9, is an endogenous source of methyl groups, and it plays an important role in regulating hepatic DNA methylation. Our previous studies found that serum folic acid concentration is inversely associated with liver histological steatosis grades and insulin resistance level measured by HOMA-IR.Further mechanism study indicated that folic acid might down-regulate the expression of a cellular adaptor protein PDLIM5 through hypermethylation of Pdlim5 gene promoter, inhibiting PKCε cellular membrane translocation and activating insulin signaling pathway in hepatocytes. However，it is still unclear whether the effect of folic acid on Pdlim5 promoter methylation is a key link in improving hepatic insulin resistance, and whether this effect could pass on to the next generation. Therefore, we plan to detect the expression of PDLIM5 and its promoter methylation in liver tissue samples from patients with different grades of NAFLD,and construct Pdlim5 knock-down animal and cellular model to explore its crucial influence to the effects of folic acid in improving hepatic insulin resistance. Offsprings of the experimental mice will also be obtained by natural conception or IVF-ET technology, and the transgenerational effect of folic acid will be further investigated. Thus, this study will reveal the molecular mechanism and transgenetic effects of folic acid in improving hepatic insulin resistance and preventing NAFLD and type 2 diabetes.