五甲基槲皮素对胰岛素抵抗状态下mTOR-S6K1通路的调控作用及机制研究

The mammalian target of rapamycin(mTOR) has been proved to be closely associated with the incidence of insulin resistance and type 2 diabetes(T2DM) through influencing its downstream effector S6K1. In our previous work, we found that PMQ, a typical member of the polymethoxylated flavones family, significantly attenuated hyperglycemia,dyslipidemia and insulin resistance, up-regulated the expression level of AMP-activated protein kinase(AMPK) and adiponectin. For AMPK and adiponectin are both the upstream negative regulator of the mTOR-S6K1 pathway, we hypothesize that PMQ attenuates insulin resistance through down-regulating the over-activated mTOR-S6K1 signaling in the present research. To test this hypothesis, western blotting, real-time PCR, immunofluorescence histochemistry and recombinant adenovirus construction techniques are applied, and the insulin resistant rat model and L6 cell model induced by high-fat diet feeding and fatty acid supplementation respectively are established. Our data will verify the influence of PMQ treatment on the expression level of the mTOR-S6K1 pathway, provide valuable evidence for the mechanism research of PMQ for its anti-diabetic property, and furthermore, will shed light on the screening of new therapy targets for type 2 diabetes treatment.

哺乳动物雷帕霉素靶点（mTOR）通过作用于底物蛋白S6K1与胰岛素信号通路相关联，而其过度激活与胰岛素抵抗和2型糖尿病（T2DM）的发病密切相关。在前期工作中，我们发现多甲氧基黄酮类化合物-五甲基槲皮素（PMQ）显著改善糖脂代谢紊乱和胰岛素抵抗，上调AMP激活的蛋白激酶（AMPK）和脂联素（Adiponectin）的表达水平。由于AMPK和Adiponectin均是mTOR-S6K1通路上游的负性调节因子，因此我们推测，PMQ可下调胰岛素抵抗状态下过度激活的mTOR-S6K1通路；为此，本课题拟建立胰岛素抵抗的大鼠模型和骨骼肌L6细胞模型，运用蛋白质印迹、荧光定量PCR、免疫荧光组化和重组腺病毒载体构建等技术，明确PMQ对胰岛素抵抗状态下mTOR-S6K1通路相关信号分子表达水平的影响，以期从新的视角阐明PMQ抗T2DM效应的分子机制，也为发现抗T2DM药物新的作用靶点提供思路和线索。

近年来，越来越多的研究结果揭示了mTOR-S6K1信号通路与胰岛素抵抗以及糖脂代谢之间的密切联系。雷帕霉素是mTORC1-S6K1通路的经典抑制剂，在临床上一直被用作免疫抑制剂。本项研究以mTOR-S6K1信号通路为切入点，以雷帕霉素为工具药，通过构建胰岛素抵抗的动物模型和细胞模型，深入研究雷帕霉素对机体糖脂代谢的影响及其分子机制。我们发现，雷帕霉素可以在糖尿病小鼠模型中显著降低小鼠体重，诱发更为严重的糖脂代谢紊乱，而在棕榈酸诱导的脂肪变性细胞模型中雷帕霉素可以通过调控Sirt-1信号通路对脂肪代谢产生影响。我们的研究数据进一步明确了mTOR-S6K1信号通路在糖脂代谢稳态中所扮演的角色，为2型糖尿病及脂代谢紊乱的干预提供了可能的分子靶点，也为经典药物雷帕霉素的药理作用研究开辟了新的视角。