ChREBP及其靶基因在高脂大鼠非酒精性脂肪肝中的表达

Expression of ChREBP and its target gene in nonalcoholic fatty liver of high fat rat

目的探讨碳水化合物反应元件结合蛋白(ChREBP)及其靶基因A羟化酶(ACC)、脂肪酸合成酶(FAS)在高脂大鼠非酒精性脂肪肝(NAFLD)模型中的动态表达及作用。方法选取SD大鼠24只,随机分为高脂组和对照组。两组均于喂养第12周末处死。HE染色观察肝脏脂肪变性,逆转录酶链免疫反应(RT-PCR)和Western blot方法测定两组大鼠肝脏组织中ChREBP、ACC、FAS的mRNA表达和蛋白水平,染色质免疫共沉淀分析ChREBP与ACC、FAS基因启动子碳水化合物应答元件(ChRE)结合情况。结果成功构建高脂饮食大鼠NAFLD模型,血生化指标(ALT、AST、TC、TG)明显升高,与对照组比较差异有统计学意义(P<0.01);高脂组大鼠肝组织ChREBP mRNA、蛋白及ChRE DNA的表达水平降低,与对照组比较差异有统计学意义(P<0.01);而ACC、FAS mRNA、蛋白的表达水平增高,与对照组比较差异有统计学意义(P<0.01)。结论高脂饮食可抑制ChREBP的表达,在高脂饮食导致的NAFLD形成过程对ACC、FAS的表达起负性调控作用;ACC、FAS的表达通过其他调控途径升高而参与NAFLD的形成过程。

Objective To investigate the dynamic expressions and effects of ChREBP as well as its target genes ACC and FAS in rats with non-alcoholic fatty liver disease（NAFLD）.Methods Twenty four rats were divided randomly into hyperlipoidemia group and control group and were sacrificed after twelve weeks＇s feeding.Adipose degeneration of liver was observed by hematoxylin and eosin stain.Expressions of ChREBP,ACC and FAS in both mRNA and protein levels were detected using RT-PCR and Western blot respectively.Binding conditions between ChREBP and carbohydrate response element（ChRE） of ACC and FAS were analyzed with chromatin immunoprecipitation assay（CHIP）.Results Rat models with NAFLD feeded on high fat diets were successfully prepared,and the level of ALT,AST,TC and TG in their blood increased（P〈0.01）,expressions of ChREBP mRNA and protein and of ChRE DNA in liver decreased（P〈0.01）,levels of mRNA and protein of ACC and FAS increased（P〈0.01）,as compared to the control group.Conclusion Expression of ChREBP could be inhibited by high fat diet.NAFLD induced by high fat diet has an negative effect on expression of ACC and FAS.Increased levels of ACC and FAS participate in formation of NAFLD through other regulatory pathways.