转录因子Twist 1对肥胖致胰岛素抵抗的影响及机制研究

Obesity-induced insulin resistance (IR) is the major cause of type 2 diabetes (T2DM). Twist 1, as a transcriptional factor, is involved closely in obesity, but largely keeps unknown about the role and molecular mechanism of Twist 1 in obesity-induced IR. Literatures showed that Twist 1 was closely related with IR. Also, some studies have confirmed the critical role of dysfunctions of mitochondria in the occurrence of IR. Our previous study showed negative correlation between Twist 1 expression and occurrence of obesity based on mice and clinical specimens. Also, we found the uptake of glucose could be influenced by Twist 1. These results suggest that the effect of Twist 1 to IR of adipocytes may be related with mitochondrial biogenesis and respiration, which could further influence the transduction of insulin signaling, and induced the occurrence of IR. In this study, animal model of obesity-induced IR will be established, and expression level of Twist 1, mitochondrial biogenesis and respiration, and insulin signaling moleculors will be detected. Cultured adipocytes model of IR will also be built, Twist 1 expression will be intervened by genetic engineering, and inhibitors of insulin signaling pathway will be applied, to analyze comprehensively the role of Twist 1 in obesity-induced IR by regulating mitochondrial biogenesis and function of adipocytes. The research of this study is expected to show new molecular mechanism and provide novel targets to obesity-induced IR.

肥胖致胰岛素抵抗（IR）是Ⅱ型糖尿病发病的重要原因。转录因子Twist 1密切参与肥胖症的发生，但其表达对IR的影响及分子机制仍知之甚少。已有研究显示Twist 1与IR关系密切，且有学者证实线粒体的合成和功能障碍影响IR的发生。申请者发现Twist 1在肥胖小鼠和人体脂肪标本中表达均显著下调，且Twist 1影响脂肪细胞葡萄糖的摄取。以上结果支持Twist 1可能通过影响脂肪细胞线粒体的合成和功能调控胰岛素信号通路，进而影响IR的发生。本课题将制备肥胖致IR的小鼠模型，探讨Twist 1表达变化、线粒体的生物合成和功能改变、及胰岛素信号转导通路的变化；并建立体外培养的脂肪细胞IR模型、干预脂肪细胞中Twist 1的表达水平、借助胰岛素信号通路的抑制剂，综合分析Twist 1调控线粒体的合成和功能在肥胖致IR中的作用。本课题的研究成果将为肥胖致IR的分子生物学机制提供新的发生机制和靶点。

胰岛素抵抗（IR）已经成为一种全球性的流行病，正在严重威胁着人类健康。但是IR的分子调控机制并未阐明。本课题旨在探讨转录因子Twist 1在脂肪细胞胰岛素抵抗中的作用，并深入分析其分子机制。在本课题中，首先以体外培养的脂肪细胞3T3-L1为实验材料，高糖/高胰岛素溶液诱导建立胰岛素抵抗模型，其次体内动物实验以C57/BL6J小鼠为实验材料，高脂饮食持续诱导，建立胰岛素抵抗模型。进一步借助靶向干扰Twist 1的慢病毒载体，探讨Twist 1表达水平与机体的IR状态，线粒体功能以及下游的胰岛素信号转导通路之间的关系。研究结果发现，首先在IR的脂肪细胞中，Twist 1基因表达上调；干扰Twist 1基因表达能够拮抗IR状态。其次，线粒体超微结构的损伤，活性氧自由基（ROS）的升高，线粒体膜电位以及ATP含量的下降，以及线粒体合成和功能发挥相关基因的改变均证实在IR的脂肪细胞中线粒体功能障碍。最后，胰岛素信号通路的检测发现IRS/PI3K/AKT/GluT4途径是Twist 1基因介导的脂肪细胞胰岛素抵抗过程的效应分子。总之，本课题的研究结果揭示了干扰Twist 1基因表达在释放脂肪细胞IR状态中的潜在作用，线粒体功能障碍和下游的IRS/PI3K/AKT/GluT4胰岛素信号转导途径是Twist 1基因介导的脂肪细胞胰岛素抵抗过程的主要分子机制。