线粒体融合蛋白2抑制2型糖尿病胰岛β细胞去分化作用机制研究

Type 2 diabetes (T2DM) is a metabolic disease characterized by hyperglycaemia. Oral medications and insulin injections treat but do not cure T2DM. Recent researches showed that β cell dedifferentiation plays a critical role in β cell dysfunction of T2DM. We have demonstrated that Mitofusin2 (MFN2) regulated β cell glucose stimulated insulin secretion. Our preliminary studies showed that MFN2 expression increased during mouse embryonic pancreas development and β cell differentiation. MFN2 deficiency disturbed β cell differentiation from mouse embryonic stem cells. Furthermore, knockdown of MFN2 reduced the expressions of β cell markers, and induced pancreatic progenitor cell generation in mouse islets, indicated that MFN2 may contribute to inhibiting β cell dedifferentiation. In this study, overexpression or knockdown of MFN2 by lentiviral vectors will be applied in ES cell derived β cells differentiation, mouse isolated islets in vitro, normal and T2DM mice pancreas in vivo. We will explore the role of MFN2 in β cell dedifferentiation as well as the underlying mechanisms. The results will provide new insights into the pathogenesis of T2DM and potential targets for anti-diabetes drug discovery.

2型糖尿病是常见的内分泌代谢紊乱疾病，现有药物无法治愈该疾病。β细胞去分化是导致2型糖尿病β细胞胰岛素分泌功能障碍的重要原因，研究调控β细胞去分化靶点可为2型糖尿病治疗药物研发提供新思路。申请人前期研究发现线粒体融合蛋白2（MFN2）参与调控β细胞胰岛素分泌功能。本课题初步预实验显示MFN2在胚胎胰腺发育及胚胎干细胞分化β细胞过程表达上升，抑制MFN2表达减少β细胞体外分化；慢病毒干扰小鼠原代胰岛MFN2，减少β细胞标志蛋白表达，并诱导胰腺内分泌祖细胞生成，提示MFN2可能参与抑制β细胞去分化。基于此，本项目拟利用小鼠原代胰岛、胚胎干细胞分化β细胞体外模型及2型糖尿病动物模型，采用慢病毒载体小鼠体内胰胆管注射与体外转染技术，干扰或过表达胰岛MFN2，进一步明确MFN2抑制β细胞去分化作用与机制，以期为认识2型糖尿病发病机制、寻找新的治疗2型糖尿病药物作用靶点作出贡献。

2型糖尿病是常见的内分泌代谢紊乱疾病，现有药物无法治愈该疾病。β细胞去分化是导致2型糖尿病β细胞胰岛素分泌功能障碍的重要原因，研究调控β细胞去分化靶点可为2型糖尿病治疗药物研发提供新思路。申请人前期研究发现线粒体融合蛋白2（MFN2）参与调控β细胞胰岛素分泌功能。本课题利用小鼠原代胰岛、胚胎干细胞分化β细胞体外模型及2型糖尿病动物模型，采用慢病毒载体小鼠体内胰胆管注射与体外转染技术，干扰或过表达胰岛MFN2，研究MFN2对β细胞分化作用。研究结果显示Mfn2缺失可导致体外胰岛β细胞去分化，在ES细胞分化β细胞过程中，Mfn2促进成熟β细胞分化。在糖尿病db/db小鼠中胰岛过表达Mfn2后分离胰岛细胞，其GSIS功能有部分改善。利用体外ES细胞分化β细胞模型研究发现未成熟β细胞以无氧糖酵解产生乳酸为主要糖代谢模式，而在成熟β细胞中以有氧代谢产生ATP为主要糖代谢模式。在正常动物模型中胰岛细胞Mfn2缺失可导致胰岛细胞ATP产量减少。Mfn2可增强ES细胞分化的β细胞的无氧酵解向线粒体有氧代谢转化。Ras/Raf/Erk以及Sirt3/Idh2信号通路参与Mfn2维持以及促进β细胞GSIS功能成熟作用。本研究结果有望为认识2型糖尿病发病机制、寻找新的治疗2型糖尿病药物作用靶点作出贡献。