二甲双胍抑制SREBP-1c改善高脂诱导的骨骼肌胰岛素抵抗  

Metformin ameliorates PA-induced skeletal muscle insulin resistance by suppressing SREBP-1c

作　　者：吴文君[1,2] 汤孙寅炎 时俊锋[3] 尹雯雯[1] 曹殊[1] 朱大龙[1] 毕艳[1] 

机构地区：[1]南京大学医学院附属南京市鼓楼医院内分泌科,江苏南京210008 [2]南京医科大学附属无锡市人民医院内分泌科,江苏无锡214023 [3]南京医科大学附属南京市第一医院肿瘤科,江苏南京210012

出　　处：《中国药理学通报》2016年第1期55-59,共5页Chinese Pharmacological Bulletin

基　　金：国家自然科学基金资助项目(No 81270906 81500630);南京医科大学科技发展基金(No 2013NJMU155)

摘　　要：目的二甲双胍已成为治疗2型糖尿病的一线药物,前期研究结果提示固醇调节元件结合蛋白-1c(sterol regulatory element binding protein-1c,SREBP-1c)抑制胰岛素受体底物-1(insulin receptor substrate-1,IRS-1)基因转录表达,在高脂诱导骨骼肌胰岛素抵抗中起关键作用。该研究探讨SREBP-1c在二甲双胍改善高脂诱导骨骼肌胰岛素抵抗中的作用及机制。方法经500μmol·L-1PA处理的L6细胞被二甲双胍(1、10 mmol·L-1)干预24 h后,采用2-NBDG方法检测其葡萄糖摄取水平,Western blot检测SREBP-1c、FAS、p-IRS-1(Tyr608/612)、IRS-1、p-AKT(Ser473)、AKT的蛋白表达。双荧光素酶报告基因实验检测二甲双胍对SREBP-1c和IRS-1基因转录的调控。CHIP定量分析二甲双胍处理后SREPB-1c蛋白与IRS-1启动子区域的相互作用。结果 L6肌管细胞经PA处理后,糖摄取下降,SREBP-1c及其下游分子FAS表达升高,胰岛素信号通路相关分子p-IRS-1(Tyr608/612)、IRS-1、p-AKT(Ser473)/AKT表达下降;不同浓度二甲双胍干预后,L6肌管细胞糖摄取呈剂量依赖性增加,SREBP-1c、FAS表达下降,而p-IRS-1(Tyr608/612)、IRS-1、p-AKT(Ser473)/AKT表达升高。双荧光素酶报告基因实验结果显示二甲双胍抑制SREBP-1c启动子活性,增加IRS-1启动子活性。CHIP结果显示二甲双胍使SREBP-1c蛋白结合到IRS-1启动子区域的量下降约30%。结论二甲双胍通过抑制SREBP-1c改善高脂诱导的骨骼肌胰岛素抵抗。Aim Metformin has been the first-line oral agent for the treatment of type 2 diabetes. The results from preliminary studies suggested that sterol regulatory element binding protein-1c( SREBP-1c) inhibited the transcription of insulin receptor substrate-1( IRS-1),which plays a key role in PA-induced skeletal muscle insulin resistance. In the current study,we investigated the role and mechanism of SREBP-1c in metformin ameliorating PA-induced skeletal muscle insulin resistance. Methods L6 cells were treated with metformin( 1,10 mmol·L- 1) for 24 h in 500 μmol·L- 1PA-induced insulin-resistant state and then harvested for protein and glucose uptake assay. Glucose uptake was performed by 2-NBDG method. The protein expression of SREBP-1c,FAS,p-IRS-1( Tyr608 /612),IRS-1,p-AKT( Ser473) and AKT was detected by western blot. The effects of metformin on SREBP-1c and IRS-1gene transcription were assessed by a dual-luciferase reporter assay. CHIP assay was performed to examine the binding of SREBP-1c protein to the IRS-1 promoter region by metformin treatment. Results PA treatment decreased glucose uptake in L6 myotubes. The protein expression of SREBP-1c and its downstream molecule FAS was increased significantly after exposure to PA.By contrast,the proteins related to insulin signaling pathway including IRS-1,p-IRS-1( Tyr608 /612) and p-AKT( Ser473) / AKT were decreased significantly.Metformin increased glucose uptake in a dose-dependent manner compared to PA-cultured L6 cells. The SREBP-1c and FAS protein levels were decreased by metformin treatment. Correspondingly, p-IRS-1( Tyr608 /612),IRS-1,p-AKT( Ser473) /AKT protein levels were increased significantly. The results from dual-luciferase reporter assay indicated metformin suppressed SREBP-1c promoter activity and enhanced IRS-1 promoter. The results from CHIP assay showed that metformin decreased binding of SREBP-1c protein to the IRS-1 promoter region( about 30%). Conclusion Metformin can improve PA-induced muscular insulin resistance by suppressing SREBP-1c.

关 键 词：二甲双胍 固醇调节元件结合蛋白-1C 胰岛素受体底物-1 棕榈酸 骨骼肌细胞 胰岛素抵抗 

分 类 号：R322.74[医药卫生—人体解剖和组织胚胎学] R341[医药卫生—基础医学]