TBX1在肥胖诱导骨骼肌胰岛素抵抗中的作用机制研究

Insulin resistance is the common pathophysiological basis of various obesity related diseases, and is one of the main causes of type 2 diabetes. As the main peripheral target organ of insulin, skeletal muscle plays a key role in the occurrence of insulin resistance. However, the relationship between skeletal muscle and insulin resistance is not clear. TBX1 is an important transcription factor, but whether it is involved in the occurrence of skeletal muscle insulin resistance has not been reported. In the preliminary studies, we used high throughput sequencing to study the whole genome methylation and gene expression profiles of skeletal muscles in obese and healthy samples. By integration of multi-omics data and verification in more samples， we found that the methylation level of TBX1 promoter in skeletal muscle of obese patients was significantly decreased, and methylation level was significantly correlated with gene expression. Based on this, we speculate that TBX1 may be involved in the formation of insulin resistance in skeletal muscle by changing gene expression through the regulatory of methylation state. Based on the cellular and animal models, a variety of experimental methods, such as quantitative PCR, Western blot, adeno-related virus infection and chromatin immunoprecipitation will be applied to study on the mechanism of TBX1 in the development of insulin resistance in skeletal muscle. Our studies may provide a great help in the discovery of new insulin resistance specific therapeutic targets.

胰岛素抵抗是多种肥胖相关性疾病的共同病理生理基础，是造成2型糖尿病的主要原因之一。骨骼肌作为胰岛素的主要外周靶器官，在胰岛素抵抗的发生中起关键作用，然而其与胰岛素抵抗之间的关系并不明确。TBX1是一种重要的转录因子，但其是否参与骨骼肌胰岛素抵抗的发生尚未见报道。在前期研究中，我们使用高通量测序研究了肥胖和健康人骨骼肌的全基因组甲基化谱和基因表达谱。通过多组学整合分析并扩大样本验证后发现，TBX1在肥胖病人骨骼肌中启动子甲基化水平显著降低，且与表达量呈显著相关。基于此，我们推测TBX1可能是通过甲基化状态改变调控基因表达，从而参与骨骼肌胰岛素抵抗的形成。本项目拟在细胞和动物模型上，利用定量PCR、蛋白印迹、腺相关病毒感染、染色质免疫共沉淀等多种实验方法，研究TBX1在骨骼肌胰岛素抵抗发生中的作用机制，为发现新的胰岛素抵抗特异性治疗靶点提供依据。

本项目主要聚焦于探究DNA甲基化状态的改变在肥胖、2型糖尿病以及胰岛素抵抗中的作用机制。在前期研究中，我们使用高通量测序研究了肥胖和健康人骨骼肌的全基因组甲基化谱和基因表达谱。通过多组学整合分析并扩大样本验证后发现，肥胖患者骨骼肌中TBX1和FGF6这两个基因启动子区域甲基化水平发生了显著改变，并且甲基化水平和基因表达量呈显著相关性。基于此，我们对这两个基因开展了进一步的功能学研究，并且在细胞和动物模型上揭示了FGF6在调节骨骼肌蛋白合成和能量代谢稳态中的作用。FGF6启动子区CRE的高甲基化抑制了CREB1的结合，导致转录被抑制；在小鼠骨骼肌中过表达Fgf6可激活mTOR信号通路，促进蛋白合成，引起骨骼肌肥大，并且可以部分逆转高脂诱导的体重和脂肪的增加，从而改善糖脂代谢。针对FGF6的DNA甲基化编辑或AAV基因治疗策略的开发或许可以为肥胖患者的代谢调控提供新的思路。此外，我们还成功建立了肥胖合并2型糖尿病大鼠模型，发现减重手术对DNA甲基化具有重塑作用。本项目累计发表SCI论文5篇，其中IF>5分的有2篇，参与培养博士研究生4名。

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