目的 探讨姜黄素(curcumin)调控沉默信息调节因子 1(silent mating-type information regulation 2 homolog 1,SIRT1)/叉头盒蛋白O1(forkhead box protein O1,FoxO1)信号通路防控非酒精性脂肪肝(nonalcoholic fatty liver disease,NAFLD)的作用及机制.方法 采用脂肪酸诱导HepG2 细胞 24 h建立NAFLD体外模型,油红O染色后光镜下观察细胞内脂肪变性,透射电镜观察细胞内自噬体形成,比色法检测细胞内总胆固醇(total cholesterol,TC)、甘油三酯(triglyceride,TG)含量,免疫印迹法检测细胞内沉默信息调节因子 1(silent mating type information regulation 2 homolog 1,SIRT1)、乙酰化叉头盒蛋白O1(acetylated forkhead box protein O1,AC-FoxO1)、微管相关蛋白 1 轻链 3(microtubule-associated protein 1 light chain 3,LC3)、选择性自噬接头蛋白 1(sequestosome 1,SQSTM1/P62)、自噬相关蛋白 7(autophagy related protein 7,ATG7)蛋白质表达,免疫荧光观察细胞内SIRT1 和FoxO1 蛋白质共定位.结果 姜黄素可改善细胞内脂肪变性,自噬体增加,显著降低 TC、TG 含量及 AC-FoxO1、P62 蛋白质表达(P＜0.01),显著升高 SIRT1、ATG7 蛋白质表达及 LC3-Ⅱ/LC3-I比值(P＜0.01).干扰 SIRT1 表达显著影响了姜黄素对细胞的保护作用及相关蛋白质的调控(P＜0.05 或P＜0.01);姜黄素通过激活SIRT1,增强细胞中FoxO1 核定位.干扰SIRT1 表达,FoxOl大量迁入细胞质区,SIRT1 和FoxOl共定位减少.结论 姜黄素通过激活SIRT1 促进FoxO1 脱乙酰化,诱导自噬,改善肝细胞脂肪变性.
THE ROLE AND MECHANISM OF CURCUMIN IN REGULATING THE SIRT1/FOXO1 SIGHALING PATHWAY TO PREVENT NONALCOHOLIC FATTY LIVER DISEASE
Objective To investigate the effect and mechanism of curcumin on nonalcoholic fatty liver disease(NAFLD)via regulating silent mating-type information regulation 2 homolog 1(SIRT1)/forkhead box protein O1(FoxO1)signal pathway in HepG2 cells.Methods HepG2 cells were induced by fatty acids for 24 hours to establish an in vitro model of NAFLD.After staining with oil red O,the cellular steatosis was observed under light microscope,and the formation of autophage was observed under transmission electron microscope.The levels of total cholesterol(TC)and triglyceride(TG)in cells were measured by colorimetry.The expressions of SIRT1,acetylated forkhead box protein O1(AC-FoxO1),microtubule-associated protein 1 light chain 3(LC3),sequestosome 1(SQSTM1/P62)and autophagy related protein 7(ATG7)were detected by Western blot.The co-localization of SIRT1 and FoxO1 proteins in cells was observed by immunofluorescence.Results Curcumin could improve cellular steatosis,increase autophagy,and significantly reduce the contents of TC and TG and the expressions of AC-FoxO1 and P62 proteins(P<0.01).The protein expressions of SIRT1,ATG7 and the ratio of LC3-Ⅱ/LC3-Ⅰ were significantly increased(P<0.01).Curcumin also enhanced nuclear localization of FoxO1 in cells by activating SIRT1.By interfering with the expression of SIRT1,a large number of FoxOl migrated into the cytoplasmic region,and the co-localization of SIRT1 and FoxOl decreased.Conclusion Curcumin prevents NAFLD by regulating SIRT1/FoxO1 pathway,in which curcumin can promote the deacetylation of FoxO1,induce autophagy,and improve hepatocyte steatosis by activating SIRT1.
curcuminnonalcoholic fatty liver disease(NAFLD)silent mating-type information regulation 2 homolog 1(SRIT1)forkhead box protein O1(FoxO1)autophagy
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