Cell signaling and transcription factors in pancreatic islet development and function

项目总结和摘要 在过去的几十年里，美国糖尿病患者的数量稳步增加 2020年的报告显示，近10.5%的人口患有这种疾病， 死亡人数和估计成本为3270亿美元。虽然巨大的努力是针对管理糖尿病， 无法治愈一种有希望的治疗方法是胰岛替代疗法，解决了胰岛移植中的一个主要潜在问题。 1型和2型糖尿病：功能障碍和死亡的β细胞。然而，这种治疗并不广泛。 因为缺乏捐赠材料。为了克服这一限制，可以将产生胰岛素的β细胞 在体外从人类多能干细胞（hPSC）中产生，但尽管取得了巨大的进步，即使是最好的协议， 不能有效地产生用于移植的成熟β细胞群。为了改进这种治疗策略， 有必要使用体内模型阐明胰腺发育的机制， 细胞分化方案。几乎所有用于制定这些协议的信息都来自于 在小鼠中进行的发育研究，提供了一个路线图，详细说明了顺序添加或去除 或信号传导因子来促进β细胞形成。例如，视黄酸（RA）被包括在所有疾病的早期阶段。 β细胞分化方案，以指定胰腺祖细胞，模拟在 小鼠尽管RA在胰腺发育开始时的重要性，但在小鼠或小鼠中， 人类胰腺发育为了解决这一知识差距，我们进行了研究，确定了一个新的作用， 内分泌祖细胞特化过程中的RA，其中RA抑制WNT信号传导以促进β细胞 分化由于RA在这一过程中显然不是单独行动的，我也开始研究加塔的作用 胰腺发育过程中的因素，因为以前的工作已经证明了RA-GATA协同作用， 几种模型，包括人β细胞分化。此外，人类中GATA 6的单倍不足 在超过50%的病例中导致胰腺发育不全，然而在小鼠和人β细胞中也存在相同的缺失。 分化导致次要表型，这表明背景修饰剂，如RA信号，可能是 扮演着重要的角色。我在这份提案中所描述的初步研究表明， 小鼠中RA和GATA TF之间的关系：同时抑制导致RA和GATA TF的数量急剧减少和功能障碍 在发育和成年期导致严重生理缺陷的内分泌细胞。与 从这些初步数据的指导，我将阐明内分泌特化的调节机制， β细胞发育和胰岛功能，通过检验RA信号和加塔之间的协同作用的假设， 转录因子是胚胎胰腺发育和成年胰岛功能所必需的。

PROJECT SUMMARY AND ABSTRACT Over the past several decades the number of people in the United States with diabetes has steadily increased and reports from 2020 indicate nearly 10.5% of the population have the disease, leading to more than 270,000 deaths and an estimated cost of $327 billion. While tremendous effort is directed towards managing diabetes, there is no cure. One promising treatment is islet replacement therapy, addressing a major underlying issue in both type 1 and type 2 diabetes: dysfunctional and dying β cells. This treatment, however, is not widely accessible because of a lack of donor material. To overcome this limitation, insulin producing β cells can be generated from human pluripotent stem cells (hPSCs) in vitro, but despite great strides even the best protocols are unable to efficiently produce mature β cell populations for transplant. To improve this therapeutic strategy, it is essential to clarify mechanisms of pancreas development using in vivo models that will allow us to refine β cell differentiation protocols. Nearly all of the information used to formulate these protocols is derived from developmental studies in mice, which have provided a roadmap specifying the sequential addition or removal or signaling factors to promote β cell formation. For example, retinoic acid (RA) is included in early stages of all β cell differentiation protocols to specify pancreatic progenitors simulating numerous studies conducted in mice. Despite its importance at the onset of pancreas development, little is known about RA later in mouse or human pancreagenesis. To address this knowledge gap, we performed studies that identified a novel role for RA during endocrine progenitor specification where RA represses WNT signaling to promote β cell differentiation. Since RA clearly does not act alone in this process, I also began to examine the role of GATA factors during pancreas development as well, since previous work has demonstrated RA-GATA synergy in several models, including human β cell differentiations. Furthermore, haploinsufficiency of GATA6 in humans leads to pancreas agenesis in more than 50% of cases, yet this same deletion in mice and human β cell differentiations results in minor phenotypes, suggesting that background modifiers, like RA signaling, could be playing a major role. My preliminary studies described in this proposal demonstrate significant synergy between RA and GATA TFs in mice: simultaneous inhibition leads to drastically fewer and dysfunctional endocrine cells that contributes to severe physiological defects during development and adulthood. With guidance from these preliminary data, I will clarify the regulatory mechanisms defining endocrine specification, β cell development, and islet function by testing the hypothesis that synergy between RA signaling and GATA transcription factors is essential for embryonic pancreas development and adult islet function.