N1-methylnicotinamide ameliorates insulin resistance in skeletal muscle of type 2 diabetic mice by activating the SIRT1/PGC-1α signaling pathway
N1-methylnicotinamide ameliorates insulin resistance in skeletal muscle of type 2 diabetic mice by activating the SIRT1/PGC-1α signaling pathway
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DOI：
10.3892/mmr.2021.11909
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发表时间：
2021-04-01
影响因子：
3.4
通讯作者：
Li, Ling
中科院分区：
文献类型：
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作者：
Chen, Yu;Zhang, Jingfan;Li, Ling
胰岛素抵抗是导致2型糖尿病的重要因素之一；因此，调节胰岛素敏感性被认为是治疗2型糖尿病的一种有益方法。本研究旨在确定N1 - 甲基烟酰胺（MNAM）对2型糖尿病（T2DM）小鼠模型骨骼肌胰岛素抵抗（IR）的影响，并研究沉默调节蛋白1（SIRT1）/过氧化物酶体增殖物激活受体γ辅激活因子 - 1α（PGC - 1α）信号通路的调节机制。C57BL/6小鼠分别喂食含或不含1% MNAM的正常饮食，ob/ob小鼠也分别喂食含或不含0.3%或1% MNAM的正常饮食。采用酶联免疫吸附测定（ELISA）检测血糖、胰岛素水平、胰岛素抵抗（IR）、敏感性指数和甘油三酯（TG）含量。采用逆转录 - 定量聚合酶链反应（RT - qPCR）和蛋白质印迹法分析糖异生相关、胰岛素信号相关以及SIRT1/PGC - 1α通路相关蛋白的表达。在体外，利用C2C12细胞通过0.75 mM棕榈酸（PA）处理建立胰岛素抵抗肌肉细胞模型（PA组）。随后向胰岛素抵抗细胞模型中添加1 mM MNAM（PM组）或1 mM MNAM + 30 μM SIRT1抑制剂EX527（PME组）。处理后，分别采用ELISA和蛋白质印迹法检测葡萄糖水平和胰岛素信号相关蛋白。此外，采用RT - qPCR和蛋白质印迹法检测MNAM处理下SIRT1/PGC - 1α信号通路相关mRNA和蛋白的表达水平。MNAM降低了T2DM小鼠的体重增加，降低了空腹血糖和空腹胰岛素水平，并抑制了胰岛素抵抗。MNAM还调节胰岛素信号转导，促进骨骼肌中的葡萄糖利用，并减少脂质沉积。因此，MNAM改善了T2DM小鼠骨骼肌中的胰岛素抵抗。应用SIRT1抑制剂后，MNAM对胰岛素抵抗肌细胞中葡萄糖利用增加以及胰岛素信号通路的作用被抑制。其作用机制与SIRT1/PGC - 1α信号通路的激活有关，该通路促进了胰岛素受体底物IRS1/PI3K/AKT通路的激活。
Insulin resistance is one of important factors causing type 2 diabetes; therefore, regulating insulin sensitivity is considered a beneficial therapeutic approach against type 2 diabetes. The present study aimed to determine the effects of N1-methylnicotinamide (MNAM) on insulin resistance (IR) in skeletal muscle from a mouse model of type 2 diabetes mellitus (T2DM), and to investigate the regulatory mechanisms of the sirtuin 1 (SIRT1)/peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1 alpha) signaling pathway. C57BL/6 mice were fed a normal diet with or without 1% MNAM and ob/ob mice were also fed a normal diet with or without 0.3 or 1% MNAM. Blood glucose, insulin levels, insulin resistance (IR), sensitivity indices and triglyceride (TG) content were detected using ELISAs. The expression of gluconeogenesis-related, insulin signaling-related and SIRT1/PGC-1 alpha pathway-related proteins was analyzed using reverse transcription-quantitative PCR (RT-qPCR) and western blotting. In vitro, C2C12 cells were used to establish an IR muscle cell model by 0.75 mM palmitic acid (PA) treatment (PA group). The IR cell model was subsequently supplemented with 1 mM MNAM (PM group) or 1 mM MNAM + 30 mu M SIRT1 inhibitor, EX527 (PME group). After treatment the glucose levels and insulin signaling-related proteins were detected by ELISAs and western blotting, respectively. Furthermore, the expression levels of SIRT1/PGC-1 alpha signaling pathway-related mRNA and proteins under MNAM treatment were detected by RT-qPCR and western blotting. MNAM reduced body weight gain in T2DM mice, decreased fasting blood glucose and fasting insulin levels, and inhibited IR. MNAM also regulated insulin signal transduction and promoted glucose utilization in skeletal muscle, and reduced lipid deposition. Thus, MNAM improved IR in the skeletal muscle of T2DM mice. Following application of a SIRT1 inhibitor, the effects of MNAM on the increased glucose utilization in insulin-resistant myocytes and the insulin signaling pathway were suppressed. The mechanism of action was associated with activation of the SIRT1/PGC-1 alpha signaling pathway, which promoted the activation of the insulin receptor substrate IRS1/PI3K/AKT pathway.