Identifying Physiological and Molecular Inducers of Beta Cell Maturation

描述（由申请人提供）：糖尿病是一种血糖调节紊乱的疾病，在美国影响超过8%的人。在糖尿病中，胰岛中产生胰岛素的β细胞无法正常维持 正常的血糖水平，因为β细胞数量不足或β细胞功能不足。通过替代胰岛治疗糖尿病已被提出作为一种治疗策略，但可移植材料有限。了解如何从替代来源产生功能性β细胞可以绕过这一限制，并使胰岛替代疗法成为可能。目前用于体外产生β细胞的方法产生表达胰岛素的细胞，但其类似于具有有限葡萄糖调节能力的胎儿或新生儿β细胞。该项目将研究通常诱导胰岛从不成熟的低功能状态转变为能够有效调节血糖的成熟细胞类型的生理和分子信号。为了实现这一点，我们将首先测试通过在培养的胰岛中实验性地诱导预定的电活动来模拟正常葡萄糖诱导的细胞去极化是否足以将未成熟的出生后β细胞转化为成熟和完全功能的β细胞。电活性将通过在β细胞中特异性表达光遗传蛋白来控制，当细胞暴露于特定波长的光时，这将产生穿过细胞膜的电流。其次，我们将测试激活钙调磷酸酶/NFAT信号通路是否足以促进培养的未成熟胰岛的成熟，该信号通路感知细胞钙水平并通常控制β细胞增殖和功能。这些研究将揭示控制胰岛在发育过程中如何正常获得功能的细胞和分子刺激，并将为从可再生资源中产生新的功能性β细胞的努力提供信息。

DESCRIPTION (provided by applicant): Diabetes mellitus is a disease of disordered regulation of blood sugar, affecting over eight percent of people in the United States. In diabetes, the insulin-producing beta cells of the pancreatic islets are unable to properly maintain normal blood glucose levels because of either insufficient beta cell number or insufficient beta cell function. Treating diabetes by replacing islets has been proposed as a therapeutic strategy, but transplantable material is limited. Understanding how to produce functional beta cells from alternate sources could bypass this limitation and enable islet replacement therapies. Current methods for in vitro generation of beta cells produce cells that express insulin, but that resembles fetal or neonatal beta cells with limited glucose-regulating capacity. This project will investigate the physiological and molecular signals that normally induce islets to transition from an immature less-functional state to a mature cell type capable of effective blood glucose regulation. To achieve this, we will first test whether mimicking normal glucose-induced cell depolarization by experimentally inducing scheduled electrical activity in cultured islets is sufficient to convert immature postnatal beta cells into mature and fully functional beta cells. Electrical activity will be controlled by expressing optogenetic proteins specifically in beta cell, which will produce an electrical current across the cell membrane when cells are exposed to a specific wavelength of light. Second, we will test whether activating the Calcineurin/NFAT signaling pathway, which senses cellular calcium levels and normally controls beta cell proliferation and function, is sufficient to promote maturation of cultured immature islets. These studies will reveal cellular and molecular stimuli that control how islets normally acquire functio during development, and will inform efforts at generating new functional beta cells from renewable sources.