Mechanisms of Pancreatic Beta Cell Specification

描述（由申请人提供）：葡萄糖稳态的维持对我们的健康至关重要，其失败会导致糖尿病。尽管目前的治疗方案是每天注射几次胰岛素，但糖尿病患者的血糖水平仍然波动很大，使糖尿病成为美国第六大死亡原因。胰岛素注射的替代方法包括试图通过产生分泌胰岛素的细胞疗法来治疗糖尿病。-人类胚胎干细胞（hESCs）细胞或通过重新编程其他细胞类型？——细胞。然而，尽管在将hESCs分化为胰岛素表达细胞方面取得了一些成功，但这些细胞表达多种激素，不能逆转糖尿病。生成真正的函数的主要瓶颈是什么？-对其他细胞来源的细胞是如何缺乏认识的？指定-cells。我们观察到，在内分泌祖细胞中有条件的、稳定的转录因子Nkx6.1的激活引入了一个？-细胞命运偏向和不倾向分化为非？-cell胰岛细胞类型。此外，我们发现Nkx6.1是维持？-成年小鼠基因表达的细胞特异性程序。本提案下的研究将(a)定义指定？(b)直接测试Nkx6.1是否可以重编程非-？-细胞胰岛细胞成？(c)从遗传学角度剖析Nkx6.1调控成人？-细胞命运的维持、增殖和功能。从这些研究中获得的知识将有助于制定策略来解决hesc来源的内分泌细胞的混合内分泌谱系模式，并将其他细胞类型重新编程为功能齐全的？

DESCRIPTION (provided by applicant): Maintenance of glucose homeostasis is central to our health and its failure results in diabetes mellitus. Despite current treatment regimens of several insulin injections per day, blood glucose levels still fluctuate significantly in diabetic patients, making diabetes the sixth leading cause of death in the United States. Alternative approaches to insulin injections include attempts to develop a cell therapy for diabetes by producing insulin- secreting ?-cells from human embryonic stem cells (hESCs) cells or by reprogramming other cell types into ?- cells. However, despite some success to differentiate hESCs into insulin-expressing cells, these cells express multiple hormones and are not capable of reversing diabetes. The main bottleneck for generating true functional ?-cells from other cell sources is the paucity of knowledge of how ?-cells are specified. We observed that conditional, stable activation of the transcription factor Nkx6.1 in endocrine progenitors introduces a ?-cell fate bias and disfavors differentiation into non-?-cell islet cell types. Moreover, we found that Nkx6.1 is required to maintain expression of ?-cell-specific programs of gene expression in adult mice. Research under this proposal will (a) define the molecular cues that specify ?-cells and repress alternative endocrine cell fates, (b) directly test whether the Nkx6.1 can reprogram non-?-cell islet cells into ?-cells in vivo and (c) genetically dissect the gene regulatory network controlled by Nkx6.1 in the regulation of adult ?-cell fate maintenance, proliferation and function. Knowledge gained from these studies will help devise strategies to resolve mixed endocrine lineage patterns in hESC-derived endocrine cells and to reprogram other cell types into fully functional ?-cells.