Mammalian Target of Rapamycin (mTOR) Sigaling Pathway Involved in the Inhibition of Silence Information Regulator1(Sirt1) on Fat Deposition of Mice | 雷帕霉素靶蛋白(mTOR)信号通路参与沉默信息调节因子1(Sirt1)抑制小鼠脂肪沉积

Chinese. 探讨沉默信息调节因子1(Sirt1)对小鼠脂肪沉积的抑制作用和雷帕霉素靶蛋白(mTOR)信号通路的影响。用Sirt1的激动剂白藜芦醇(100 mg•kg-1•d-1)和抑制剂尼克酰胺(500 mg•kg-1•d-1)灌胃处理小鼠(Mus mussulus)15 d，记录小鼠体质量变化，测定小鼠皮下脂肪、附睾脂肪和肾周脂肪的沉积量，试剂盒测定血脂指标，同时利用Real-time PCR分析与脂肪生成密切相关的转录因子过氧化物酶体增殖物激活受体γ(PPARγ)、固醇调节元件结合蛋白1 (SREBP1)和脂解基因甘油三酯水解酶(ATGL)、激素敏感性脂肪酶(HSL)、围脂滴蛋白(Perilipin)及生脂基因脂肪酸合成酶(FAS)mRNA的表达水平，检测mTOR通路关键因子雷帕霉素靶蛋白(mTOR)、核糖体S6蛋白激酶1(S6K1)和真核启动因子4E结合蛋白1(4EBP1)mRNA表达水平。与对照组相比，白藜芦醇处理组小鼠体质量增加量和体脂含量均显著降低(P0.01)，血清中甘油三酯(TG)、总胆固醇(TC)和低密度脂蛋白(LDL-C)浓度均显著降低(P0.01)，而高密度脂蛋白(HDL-C)浓度升高(P0.01)，mTOR通路关键因子mTOR、4EBP1和S6K1 mRNA表达水平降低(P0.01)，脂代谢相关基因PPARγ、SREBP1及成脂基因FAS mRNA表达水平显著降低(P0.01)，脂解相关基因ATGL、HSL和Perilipin mRNA表达水平显著升高(P0.01)；烟酰胺处理组小鼠体质量、附睾脂肪以与皮下脂肪沉积量增加缓慢(P0.05)，肾周脂肪沉积量增加(P0.05)，血清中LDL-C浓度升高(P0.05)，HDL-C浓度降低(P0.01)，mTOR通路关键因子mTOR和4EBP1 mRNA表达水平升高(P0.01)，而脂代谢调控相关因子PPARγ和SREBP1 mRNA水平升高(P0.05)，ATGL mRNA表达量显著降低(P0.05)，FAS、HSL和Perilipin mRNA表达量变化不显著(P0.05)。表明激活Sirt1可减少脂肪合成，增加脂肪分解，从而降低体脂沉积，而mTOR信号通路参与这个过程。

English. This study aimed at exploring the inhibition of silence information regulator1 (Sirt1) on fat deposition of mice and the influence of mammalian target of rapamycin (mTOR) pathway. Mice(Mus mussulus) were treated with the activator of Sirt1 resveratrol (100 mg•kg-1•d-1) and the antagonists nicotinamide (100 mg•kg-1•d-1) by gavage daily for 15 days. The body weight, subcutaneous fat tissue, periepdidymal fat pads and perirenal fat pads were weighed, while the concentrations of triglycerides(TG), total cholesterol (TC), low density lipoprotein (LDL-C) and high density lipoprotein (HDL-C) were measured by Kits. The mRNA expression of transcriptional regulation factors peroxisome proliferator-activated receptor γ (PPARγ), sterol regulatory element-binding protein 1 (SREBP1) as well as adipose decompose related gene adipose triglyceride lipase (ATGL), homrnoe-snestive lipaes (HSL), perilipin and fat synthesis gene fatty acid synthetase (FAS) mRNA were measured by Real-time PCR. Simultaneously, the levels of the key factors of mTOR pathway mammalian target of rapamycin (mTOR), eukaryotic initiation factor 4E binding protein 1 (4EBP1) and P70 ribosomal protein S6 kinases 1 (S6K1) mRNA were also measured by Real-time PCR. Compared with the control, resveratrol could decreased the increase of body mass and the body fat content(P0.01), obviously decreased the concentrations of TG, TC and LDL-C in blood serum (P0.01), and visibly increased the concentrations of HDL-C(P0.01). The expression levels of the key fatcors of mTOR pathway: mTOR, 4EBP1 and S6K1 mRNA, were down-regulated(P0.01), the major transcriptional factors PPARγ, SREBP1 and fat synthesis gene FAS mRNA were also distinctly reduced(P0.01), while the mRNA expression of adipose decompose related genes ATGL, HSL and Perilipin mRNA were up-regulated significantly(P0.01). Body weight, periepdidymal fat pads and subcutaneous fat tissue increased a little(P0.05) in nicotinamide-treatment mice, while perirenal fat pads increased(P0.05), the levels of HDL-C up-regulated(P0.05) as well as LDL-C reduced significantly(P0.01) in nicotinamide-treatment mice. The expression levels of the key factors of mTOR pathway mTOR and 4EBP1 mRNA were obviously down-regulated(P0.01), and the major transcriptional factors PPARγ and SREBP1 mRNA increased(P0.05), as well as adipose decompose related gene ATGL mRNA decreased(P0.05), but the expression of HSL and Perilipin were not significant(P0.05), and the expression levels of fat synthesis gene FAS were also not significant(P0.05).We demonstrated that activate Sirt1 can reduce fat synthesis, increase fat breakdown and reduce body fat deposition, and mTOR pathway involves in this process.