碳水化合物反应元件结合蛋白活性增加在2型糖尿病模型db/db小鼠肝脂质过度沉积中的作用  

Role of increased activity of carbohydrate response element binding protein in excessive lipid accumulation in the liver of type 2 diabetic db/db mouse

作　　者：霍明[1] 臧会玲[1] 张冬娟[1] 王冰[1] 吴静[1] 张晓燕[1] 陈丽红[1] 李晶[1] 杨吉春[1] 管又飞[1] 

机构地区：[1]北京大学基础医学院生理学与病理生理学系,北京大学分子心血管教育部重点实验室,北京大学糖尿病中心,北京100191

出　　处：《北京大学学报（医学版）》2009年第3期307-312,共6页Journal of Peking University:Health Sciences

基　　金：国家自然科学基金(30670766,30530340,30870995)资助~~

摘　　要：目的:探讨碳水化合物反应原件结合蛋白(carbohydrate response element binding protein,ChREBP)在2型糖尿病小鼠肝中的表达及其在脂质代谢紊乱中的作用。方法:以10～13周龄的雄性C57BL/BKS基因背景的2型糖尿病模型db/db小鼠作为实验组,年龄、性别匹配的db/m小鼠作为对照组。首先用油红O染色的方法检测肝中沉积的中性脂肪。利用免疫组织化学方法确定ChREBP在肝内的表达分布,随后用Western blot及实时荧光定量PCR等方法分析其在db/db小鼠肝中的表达及活性,以及ChREBP靶基因乙酰辅酶A羧化酶(acetyl-coenzyme A carboxylase 1,Acc-1)、脂肪酸合成酶(fatty acid synthase,Fas)与甘油-3-磷酸酰基转移酶(glycerol-3-phosphate acyltransferase,Gpat)的表达变化。结果:db/db小鼠肝中有明显的脂质沉积现象。ChREBP蛋白弥散表达于正常小鼠肝组织中,在中央静脉周围及汇管区表达较高。在正常小鼠肝细胞内,ChREBP主要存在于胞浆中。但在db/db小鼠肝细胞内,细胞核中的ChREBP水平较对照组小鼠增加了8.2倍(P<0.01)。与之相一致,db/db小鼠肝中涉及脂质合成的一些重要的ChREBP靶基因(包括Acc-1,Fas和Gpat)的表达水平分别增加了2倍(P<0.05)、1.7倍(P<0.05)、4.2倍(P<0.05)。结论:在2型糖尿病小鼠,肝ChREBP的表达和活性的显著增加,激活了一系列与脂质合成相关基因的表达,进而促进脂肪肝的形成。本研究提示ChREBP可能成为治疗脂肪肝的潜在靶点。Objective： To study the role of the carbohydrate response element binding protein （ChREBP） in excessive lipid deposition in the liver of db/db mouse. Methods： The deposition of neu- tral lipids in the liver was evaluated by Oil Red O staining. Immunohistochemical assay was utilized to determine the localization of ChREBP protein expression in mouse liver. The expressions of ChREBP and its target genes including acetyl-coenzyme A carboxylase 1 （Acc-1）, fatty acid synthase （ Fas）, glycerol- 3-phosphate acyhransferase （Gpat） were analyzed by Real-time PCR and Western blot. Results： Signifi- cant lipid droplet deposition was detected in the livers of db/db mice. ChREBP was diffusely expressed in heptocytes with relative higher expression levels around portal and central veins. ChREBP was predomi- nantly located in the cytosol in non-diabetic db/m mice, but was translocated to the nucleus in db/db mice. Nuclear ChREBP protein levels were 8.2-fold higher in db/db mice than in db/m mice （P 〈 0. 01）. In contrast, another lipogenic transcription factor, sterol regulatory element binding protein-1 （SREBP-1）, remained unchanged. Consistent with increased nuclear ChREBP levels, expressions of ChREBP target genes involved in lipogenesis including Acc-1, Fas and Gpat were upregulated by 2-fold （ P 〈 0. 05 ）, 1.7-fold （ P 〈 0. 05 ） and 4.2-fold （ P 〈 0.05 ）, respectively, in db/db mice. Conclusion ： The db/db mouse exhibits significantly higher liver ChREBP activity, which may be associated with the development of hepatic steatosis frequently occurring in type 2 diabetes. Targeting ChREBP might repre- sent a new intervention strategy for fatty liver.

关 键 词：载体蛋白质类 脂肪肝 糖尿病 2型 葡萄糖 脂类 

分 类 号：R575.5[医药卫生—消化系统]