TRPM2通道调控线粒体异常分裂在胰岛β细胞脂毒性凋亡中的作用及机制研究

Lipotoxicity-induced pancreatic β-cell apoptosis plays an important role in the development of type 2 diabetes. Recent studies have demonstrated that palmitate (a C16-Free fatty acid)-induced pancreatic β-cell apoptosis is dependent on abnormal mitochondrial fragmentation, but the underlying mechanisms are unclear. Using the INS-1 β-cell line, our preliminary data demonstrate that palmitate induces ROS production, which is required for mitochondrial fission. Meanwhile, we demonstrate that ROS-activated TRPM2 ion channel is involved in palmitate-induced mitochondrial fission. Therefore, the hypothesis of this project is that TRPM2 ion channel plays a role in pancreatic β-cell apoptosis by regulating mitochondrial fission. To test this hypothesis, we will use some methods include confocal microscopy live-cell imaging、 siRNA and biochemistry to carry out the following work: (1) Using the INS-1 β-cell line, we will first investigate how palmitate-mediated TRPM2 activation affects cellular Ca2+ and Zn2+. We will then focus on the regulation of sub-cellular localization of Drp1 protein, mitochondrial membrane potential and mitochondrial ROS by TRPM2 channel、Ca2+ and Zn2+. (2) More importantly, we will use TRPM2-knockout mice to investigate the role of TRPM2 ion channel in palmitate-induced β-cell apoptosis. Our results will reveal a novel, potentially druggable signaling pathway for lipotoxicity-induced β-cell apoptosis, and provide new theoretical evidence for preventing and treating pancreatic β cell apoptosis in obesity-induced type 2 diabetes.

胰岛β细胞脂毒性凋亡在2型糖尿病的发生发展中扮演重要角色，研究表明β细胞脂毒性凋亡依赖线粒体的异常分裂，但是其分子机制还不清楚。我们预实验结果表明，棕榈酸促胰岛β细胞活性氧迸发致线粒体片段化，活性氧特异激活的TRPM2离子通道参与调控线粒体片段化。因此推测TRPM2通道调控线粒体异常分裂促胰岛β细胞脂毒性凋亡。为证实以上假说，本项目拟采用激光共聚焦技术、siRNA和生物化学方法开展以下研究：在棕榈酸处理的INS-1细胞中，研究TRPM2通道激活对细胞Ca2+和Zn2+的调控，其次探讨TRPM2, Ca2+和Zn2+对线粒体形态、Drp1蛋白亚细胞定位、线粒体膜电位及线粒体活性氧的调控作用；利用INS-1细胞和TRPM2基因敲除小鼠，探讨TRPM2通道在胰岛β细胞脂毒性凋亡中的作用。该研究将阐明TRMP2通道调控胰岛β细胞脂毒性凋亡的分子机制，为肥胖型糖尿病的防治提供新的药物靶点。