KLF14在非酒精性脂肪肝发病过程中的作用研究

Nonalcoholic fatty liver disease (NAFLD) is one of the most common forms of chronic liver diaease and tightly associated with type 2 diabetes and hyperlipidemia. However, the molecular determinants of NAFLD remain largely unknown. Although human genetic studies indicate that KLF14 is associated with obesity and type 2 diabetes, but the underlying pathogenesis is still unclear. In our previous study, we identified that the hepatic KLF14 expression can be regulated by nutritional status. Meanwhile, the hepatic KLF14 mRNA levels were reduced in type 2 diabetic mice and high-fat diet-induced obese mice compared with mice fed normal chow. Luciferase assays shows that KLF14 suppressed the critical lipogenesis regulator SREBP-1c promoter activity. Adenovirus-mediated overexpression of mouse KLF14 decreased expression mRNA and protein levels of SREBP-1c and many of its target genes and intracellular triglyceride content in primary hepatocytes. These findings imply a strong correlation between KLF14 expression and lipid metabolism in liver. The present project will be focused on the role of KLF14 in the regulation of SREBP-1c using primary hepatocytes models. And we expect that f KLF14 will inhibit the expression of the SREBP-1c and decrease the intracellular triglyceride content in primary hepatocytes. The performance of this project might explore a novel potential target for curing NAFLD and type 2 diabetes.

非酒精性脂肪肝（NAFLD）是一种最常见慢性肝疾病，然而其确切的发病机制还未完全清楚。遗传学研究表明转录因子KLF14与肥胖及2型糖尿病等疾病的发生、发展相关，但具体作用机理尚未明确。我们前期研究结果证实KLF14的表达受机体营养状态调节，并且在2型糖尿病和高脂诱导肥胖小鼠肝脏中表达水平显著降低；报告基因实验结果证实KLF14可以显著抑制脂肪合成关键调节因子SREBP-1c基因启动子的活性；在原代肝细胞中腺病毒介导过表达KLF14可以明显降低SREBP-1c及其下游靶基因mRNA和蛋白表达水平，由此推测KLF14可能参与机体脂代谢的调节。本研究旨在阐明KLF14在肝脏中对脂代谢调节作用中的机制，通过在原代肝细胞中研究KLF14对SREBP-1c的调节作用，观察KLF14能否缓解机体脂代谢的紊乱。本项目的开展有望为治疗NAFLD和2型糖尿病提供新靶点。

非酒精性脂肪肝疾病（NAFLD）是一种最常见的慢性肝脏疾病，然而直到目前为止其确切的发病机制尚未完全阐明。遗传学研究表明转录因子KLF14与2型糖尿病以及肥胖等疾病的发生、发展相关；然而其具体的功能还不明确。本研究发现在db/db 2型糖尿病小鼠和高脂饮食诱导的肥胖小鼠肝组织中转录因子KLF14的表达水平显著下调；荧光报告基因试验和染色体免疫共沉淀(ChIP)试验表明KLF14可以直接结合在脂肪合成关键调控因子SREBP-1c的启动子区并抑制其转录活性。体外实验证实在原代肝脏细胞中上调KLF14的表达水平可以降低SREBP-1c的mRNA和蛋白表达水平从而下调肝细胞合成和分泌TG的能力；此外，胰岛素信号通路实验表明上调KLF14的表达水平可以明显增加胰岛素刺激引起的AKT和GSK-3β的磷酸化水平。以上结果初步表明KLF14可能通过调控SREBP-1c的表达水平从而参与肝细胞脂代谢的调节。本项目的开展有可能为治疗NAFLD和2型糖尿病寻找的新的潜在靶点。