Regulation of beta cell identity and dedifferentiation

维持β细胞健康对1型和2型糖尿病都有重要影响。β细胞内的内在变化对这些需要患者终生管理的衰弱疾病的发生和发展有影响。几十年的研究已经确定了从胚胎祖细胞产生β细胞所必须发生的一系列事件，主要是使用啮齿动物模型，其中几个调控因子的缺失会破坏内分泌，特别是β细胞群体。在这里，我们使用复杂的转基因小鼠模型和人类干细胞来源的β细胞的组合来识别维持胰岛素产生细胞功能的关键信号。这一建议的首要目标是阐明转录因子Sox9的新功能，目前人们认为Sox9只在胰腺前体细胞和成年外分泌管和中央腺泡细胞中活跃。与另一种转录因子Ngn3类似，我们的数据表明Sox9在成熟的β细胞中低水平表达，在那里它发挥关键功能。Sox9缺失的后果没有剔除已知的导致青年糖尿病成熟发作(MODY)的因素后观察到的后果那么严重，从而反映了人类2型糖尿病的现实，在这种现实中，许多缺陷最终导致β细胞功能障碍的发展。我们认为，Sox9在调节β细胞发育和功能的基本方面发挥着核心作用。在第一个具体目标中，我们建议确定在成熟的啮齿动物和人类β细胞中消除Sox9的后果。我们的初步数据表明，Sox9的低水平表达支持β细胞的特性，而转录因子的丢失促进了β细胞的功能障碍。在第二个特定目标中，我们将调查强制Sox9在β细胞中表达的后果，目的是定义由转录因子控制的调控网络。我们预计，从β细胞中具有超生理水平Sox9的转基因小鼠中挖掘数据，将使我们能够将新的角色分配给以前未知的影响β细胞功能的蛋白质。在第三个具体目标中，我们重点研究Sox9调节β细胞功能的机制。我们的初步数据表明，Sox9调节初级纤毛的形成和功能，初级纤毛是一种已知的调节β细胞活动的细胞器。总而言之，我们预计，这项提案中概述的实验将提供对调控网络的更深层次的理解，这些网络是为了维持β细胞的适当和准确的功能而存在的。揭示β细胞衰竭背后的原因应该会提供新的见解，可以用来设计治疗糖尿病患者的新的治疗策略。

Maintenance of beta cell health has significant implications for Diabetes, both Type 1 and Type 2. Intrinsic changes within the beta cell have an impact on the initiation and progression of these debilitating diseases that require life-long management by the patient. Decades of research has identified the concert of events that must occur to generate a beta cell from embryonic progenitors, primarily using rodent models, and deletion of several of these regulators ablates endocrine, and specifically beta cell, populations. Here, we use a combination of sophisticated transgenic mouse models and human stem cell-derived beta cells to identify critical signals that maintain function in insulin producing cells. The overarching goal of this proposal is to elucidate novel functions of the transcription factor Sox9, currently believed to be only active in pancreas progenitors and adult exocrine duct and centroacinar cells. Similar to another transcription factor, Ngn3, our data indicate that Sox9 is expressed at low levels in mature beta cells where it performs critical functions. The consequences of Sox9 loss are less severe that those observed upon elimination of factors known to result in maturity onset of diabetes in the young (MODY), thus reflecting the reality of human Type 2 Diabetes, in which numerous defects culminate in the development of beta cell dysfunction. We pose that Sox9 plays a central role in regulating essential aspects of beta cell development and function. In the first specific aim, we propose to determine the consequences of Sox9 elimination in mature rodent and human beta cells. Our preliminary data demonstrate that low-level expression of Sox9 supports beta cell properties and loss of the transcription factor promotes beta cell dysfunction. In the second specific aim, we will investigate the consequences of forced Sox9 expression in beta cells with the goal of defining the regulatory network controlled by the transcription factor. We anticipate that mining data from transgenic mice with supra-physiological levels of Sox9 in the beta cells will allow us to assign novel roles to proteins previously not known to influence beta cell function. In the third specific aim, we focus on the mechanisms by which Sox9 modulates beta cell function. Our preliminary data indicate that Sox9 regulates formation and thus function of primary cilia, a cellular organelle known to regulate beta cell activities. In summary, we anticipate that the experiments outlined in this proposal will provide a deeper understanding of regulatory networks that are in place to maintain the appropriate and precise functioning of a beta cell. Uncovering the reasons behind beta cell failure should provide novel insights that can be exploited to devise novel therapeutic strategies for the treatment of patients with Diabetes.