HNF4α在非酒精性脂肪肝发生发展中的机制研究

Mechanisms of HNF4 Alpha in Development of Nonalcoholic Fatty Liver Disease

为了探讨非酒精性脂肪肝(Nonalcoholic fatty liver disease,NAFLD)发病机制,选用小鼠脂肪肝和离体肝原代细胞培养作为非酒精性脂肪肝模型。通过免疫印迹、逆转录-聚合酶链反应、免疫共沉淀和免疫荧光检测肝脏核因子4α(Hepatocyte nuclear factor 4-alpha,HNF4-α)核质分布、转录活性和HNF4α下游脂代谢相关基因和脂代谢的表达水平。结果显示:高脂饮食诱导肝脏脂质沉积,升高脂多糖(Lipopolysaccharide,LPS)、棕榈酸(Palmitate,PA)和肿瘤坏死因子α(Tumor necrosis factor-α,TNF-α)的表达水平,这些因子能够激活蛋白激酶C(Protein kinase C,PKC)。PKC通过磷酸化显著抑制HNF4α下游基因微粒体甘油三酯转运蛋白(Microsomal triglyceride transfer protein,MTTP)和载脂蛋白B(Apolipoprotein B,Apo B)的转录活性,妨碍肝脏低密度脂蛋白(VLDL)的装配和甘油三酯(TG)外排。过多的甘油三酯滞留在肝脏,进一步加剧脂肪肝的发展。

In order to explore the mechanism of development of nonalcoholic fatty liver disease （ Nonalcoholic fatty liver disease, NAFLD） ,the mice in vivo with fatty liver and primary hepatocyte culture were chosen as nonalcoholic fatty liver model. Western blot, Reverse transcription-polymerase chain reaction, Immunoprecipitation and Immunofluorescence techniques were used to detect the description of nucleas and cytoplasmic hepatocyte nuclear factor 4-alpha（ Hepatocyte nuclear factor 4-alpha, HNF4-α）, transcrip- tion activity and the expression level of HNF4α downstream lipid metabolism related genes and the level of lipid metabolism. The results showed that high fat diet induced hepatic lipid accumulation and increased the expression levels of lipopolysaecharide （ Lipopolysaccharide, LPS）, palmitic acid （ Palmitate, PA） and tumor necrosis factor α （ Tumor necrosis factor α, TNF-α）, while the expression levels of these factors can activate protein kinase C （ Protein kinase C, PKC）. Furthermore, the activation of PKC signifi- cantly represses the transcriptional level of HNF4α down-stream microsomal triglyceride transfer protein （Microsomal Triglyceride Transfer Protein, MTTP ） and apolipoproteinB （ ApolipoproteinB, ApoB） by mediating phosphorylation （ P 〈 0.05 ）, subsequently obvi- ously reduces assembling of very low density lipoprotein （VLDL） and hepatic exportation of triglyceride （TG） （ P 〈 0.05 ）. Excessive accumulation of triglycerides in the liver further promotes the development of NAFLD.