Gao Yuhua, Zhang Ranxi, Dai Shanshan, Zhang Xue, Li Xiangchen, Bai Chunyu
Institute of Precision Medicine, Jining Medical University, Jining, China.
Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China.
Front Cell Dev Biol. 2019 Dec 20;7:351. doi: 10.3389/fcell.2019.00351. eCollection 2019.
Autoimmune destruction of pancreatic beta cells causes absolute insulin deficiency and results in type 1 diabetes mellitus (T1DM). The substitution of healthy pancreatic beta cells for damaged cells would be the ideal treatment for T1DM; thus, the generation of pancreatic beta cells from adult stem cells represents an attractive avenue for research. In this study, a cocktail of factors was used to induce the differentiation of pancreatic beta cells from mesenchymal stem cells (MSCs). The differentiation program was divided into five stages, and the roles of the cocktail factors used during each stage were systematically elucidated. Activin A was found to phosphorylate Smad2 and Smad3 in stage III, thereby activating the TGF-β/Smad pathway. Meanwhile, the endocrine-specific transcription factor, Ngn3, and the pancreas-specific miRNAs, miR-375 and miR-26a, were dramatically elevated in stage III. We next demonstrated that Smad4, an important transcription factor in the TGF-β/Smad pathway, could bind to the promoter sequences of target genes and enhance their transcription to initiate the differentiation of beta cells. Use of SB-431542, an inhibitor of the TGF-β/Smad pathway, demonstrated and that this pathway plays a critical role in the production of pancreatic beta cells and in modulating insulin secretion. Thus, the TGF-β/Smad pathway is involved in the production of beta cells from adult stem cells by enhancing the transcription of Ngn3, miR-375, and miR-26a. These findings further underline the significant promise of cell transplant therapies for type 1 diabetes mellitus.
胰腺β细胞的自身免疫性破坏会导致绝对的胰岛素缺乏，进而引发1型糖尿病（T1DM）。用健康的胰腺β细胞替代受损细胞将是治疗T1DM的理想方法；因此，从成体干细胞生成胰腺β细胞是一个具有吸引力的研究途径。在本研究中，使用了一组因子鸡尾酒来诱导间充质干细胞（MSCs）分化为胰腺β细胞。分化程序分为五个阶段，并系统地阐明了每个阶段所使用的因子鸡尾酒的作用。发现激活素A在第三阶段使Smad2和Smad3磷酸化，从而激活TGF-β/Smad途径。同时，内分泌特异性转录因子Ngn3以及胰腺特异性miRNA miR-375和miR-26a在第三阶段显著升高。接下来我们证明，TGF-β/Smad途径中的重要转录因子Smad4可以与靶基因的启动子序列结合并增强其转录，从而启动β细胞的分化。使用TGF-β/Smad途径抑制剂SB-431542表明，该途径在胰腺β细胞的产生以及调节胰岛素分泌中起关键作用。因此，TGF-β/Smad途径通过增强Ngn3、miR-375和miR-26a的转录参与了成体干细胞生成β细胞的过程。这些发现进一步凸显了细胞移植疗法治疗1型糖尿病的巨大前景。
