Cell signaling and transcription factors in pancreatic islet development and function

项目摘要和摘要 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，导致超过27万人 死亡人数和估计成本为3270亿美元。虽然在管理糖尿病方面付出了巨大的努力， 没有治愈的方法。一种有希望的治疗方法是胰岛替代疗法，解决了 1型和2型糖尿病：功能失调和濒临死亡的β细胞。然而，这种疗法并不广泛。 由于缺乏捐赠者的材料而可以使用。为了克服这一限制，产生胰岛素的β细胞可以 由人类多能干细胞(HPSC)在体外产生，但即使是最好的方案也是如此 无法有效地产生用于移植的成熟β细胞群。为了改进这一治疗策略， 使用体内模型阐明胰腺发育的机制是至关重要的，这将使我们能够提炼β 细胞分化方案。几乎所有用于制定这些协议的信息都源自 或促进β细胞形成的信号因子。例如，维甲酸(RA)在ALL的早期阶段就包括在内 β细胞分化方案用于指定胰腺祖细胞，模拟在 老鼠。尽管类风湿性关节炎在胰腺发育初期很重要，但对小鼠或小鼠以后的类风湿性关节炎知之甚少。 人类胰腺发生学。为了解决这一知识鸿沟，我们进行了一项研究，确定了 RA在内分泌前体指定期间抑制WNT信号以促进β细胞 差异化。由于RA在这个过程中显然不是单独行动的，我也开始研究GATA的作用 几个模型，包括人类β细胞分化。此外，人类GATA6基因的单倍性不足 在超过50%的病例中导致胰腺发育不全，但在小鼠和人类β细胞中也存在同样的缺失 分化导致较小的表型，这表明背景修饰物，如RA信号，可能是 发挥了重要作用。我在这项提案中描述的初步研究证明了显著的协同效应 在小鼠的RA和GATA转录因子之间：同时抑制导致显著减少和功能障碍 使用 β细胞发育和胰岛功能，通过检验RA信号和GATA之间的协同作用 转录因子是胚胎胰腺发育和成人胰岛功能所必需的。

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.