基于调控转录因子网络探讨黄连人参对药配伍对胰岛细胞身份转换影响的分子机制

Recent research shows that the key aspect of type 2 diabetes mellitus, pancreatic β-cell dysfunction, may not be caused by the pancreatic β-cells apoptosis, but due to the conversion of pancreatic β-cells to α-cells identity through dedifferentiation and transdifferentiation of β-cells in the presence of risk factors, which may happen by activating or inhibiting the expression of corresponding transcription factors. It has been demonstrated that Coptidis-Ginseng pairing herbs possess the function of protecting pancreatic islet β-cells. To investigate the molecular mechanism of their protecting β-cells, it is hypothesized that Coptidis-Ginseng pairing herbs may regulate the transcription factors network to improve the conversion of islet cells identity and to restore the capacity of insulin secretion of islet β-cells. This project will establish in vivo model with murine type 2 diabetes induced by high glucose and high fat. The effects of Coptidis-Ginseng pairing herbs on the secretion of insulin and glucagon, the changes of the morphological structure and size and feature of β cells, as well as the number and ratio of α to β cells will be systemically observed. The correlation of Coptidis-Ginseng pairing herbs between their regulating transcription factors network (including Nkx2.2, Nkx6.1, Pdx1 and FoxO1, ARX) and their protecting islet β-cells identity will be explored. Based on the future experimental findings in this project, the molecular machnism of Coptidis-Ginseng pairing herbs on protecting pancreatic islet β cells could be illustrated.

最新研究表明2型糖尿病关键发病环节之胰岛β细胞功能障碍或许不是由于β细胞凋亡所致，而是由于胰岛β细胞在致病因素作用下经过去分化和转分化而发生了由β细胞向α细胞的身份转换，并且通过激活或抑制相关转录因子的表达而实现。黄连人参对药具有保护胰岛β细胞的功能，为探讨其分子机制，本项目提出“黄连人参对药通过调控转录因子网络改善胰岛细胞的身份转换，从而恢复胰岛β细胞的胰岛素分泌功能”的假说。本项目将构建高糖高脂诱导的小鼠2型糖尿病模型，观察黄连人参对药对胰岛素/胰高血糖素的分泌、胰岛α细胞和β细胞形态大小、结构特征和数量比例等变化的影响，探讨其调控转录因子网络（包括Nkx2.2、Nkx6.1、Pdx1、FoxO1、ARX等）和保护胰岛β细胞身份的相关性，从而阐明黄连人参对药保护胰岛β细胞功能的分子机制。

本课题基于调控胰岛细胞转录因子网络的假设，采用db/db小鼠糖尿病的模型，探讨黄连人参对药改善糖尿病的作用机制。主要检测了小鼠的糖代谢指标如空腹血糖、OGTT、血清胰岛素等；胰岛形态学改变如胰岛形态结构、大小分布、胰岛β细胞与α细胞的比例；胰岛β细胞转录因子如NKX6.1、PDX1等指标，及胰岛增殖和凋亡相关因子如ki67、caspase12、caspase3/cleaved-caspase3、bcl2/bax等；最后还检测了Notch1-ngn3信号通路。实验结果表明黄连人参对药可以显著改善糖尿病小鼠糖代谢，升高血清胰岛素及改善胰岛素抵抗；通过免疫荧光共染发现黄连人参对药能显著升高胰岛中β细胞比例，并降低α细胞的比例，同时黄连人参对药还能升高胰岛β细胞转录因子如NKX6.1和PDX1等的表达；各组小鼠胰岛的形态结构、大小分布、增殖及凋亡相关指标如ki67、caspase3/cleaved-caspase3、bcl2/bax无明显差异，但黄连人参对药显著降低caspase12的表达。同时黄连人参对药显著上调活化的Notch1表达水平和降低ngn3表达水平。因此，黄连人参对药改善糖尿病可能通过作用于Notch1-ngn3信号通路调节胰岛细胞转录因子，维持胰岛β细胞身份有关。