Role of cell polarity during islet progenitor specification and differentiation

描述(申请人提供)：胰腺多能祖细胞(MPC)可以产生所有的胰岛内分泌细胞，包括产生胰岛素的β细胞，在早期的胰腺芽上皮细胞中出现。在此期间，胰腺上皮经历了戏剧性的和短暂的层积，上皮细胞在形成多层结构时失去了它们的极性，但随着上皮的溶解和胰腺分支的开始，它们很快就恢复了极性。这种快速形态变化的机制和后果，以及潜在的细胞极性动态变化，是完全未知的。作为支持，目前该领域的思维已经转向承认3D架构对Beta细胞命运的潜在影响[5]。推动这项工作的假设认为，胰腺上皮在发育过程中的快速层化和去层化过程，以及与之相关的细胞极性的变化，直接影响内分泌细胞的命运。本研究的目的是确定胰腺分层和分解过程中细胞的极性，并测试极性决定因子Numb、Numb-like和Par3是否在胰腺形态发生、MPC规范和内分泌分化中所必需。了解内分泌β细胞获得其命运并分化为功能成熟的胰岛素产生细胞的逐步过程将推动细胞替代疗法治疗糖尿病的努力，因为这些步骤将被模仿用于体外分化或再生。 与公共卫生相关：胰岛细胞是血糖稳态的基本调节器，血糖稳态是糖尿病等疾病患者生命所必需的过程。胰岛细胞，包括产生胰岛素的β细胞，起源于早期发育的胰腺内的多能祖细胞(MPC)。在这里，我们着重于阐明上皮细胞的极性和3D结构在MPC规范中的作用，因为我们发现胚胎胰腺上皮经历了不寻常的瞬时细胞重排(层积)和细胞极性的丧失。了解胰岛细胞形成的基本步骤直接适用于为糖尿病患者创造新的产生胰岛素的β细胞用于替代治疗的努力。

DESCRIPTION (provided by applicant): Pancreatic multipotent progenitors (MPCs) that give rise to all islet endocrine cells, including insulin-producing beta cells, emerge within the early pancreatic bud epithelium. During this time, the pancreatic epithelium undergoes a dramatic and transient stratification, with epithelial cells losing their polarity as they generate a multilayered structure, but then quickly regaining it as the epithelium resolves and pancreatic branching begins [4]. The mechanisms and consequences of this rapid morphological change, and of the underlying dynamic shifts in cell polarity, are completely unknown. In support, current thinking in the field has shifted towards acknowledging the potential impact of 3D architecture on beta cell fate [5]. The hypothesis driving this work proposes that the process of rapid stratification and de- stratification of the pancreatic epithelium during development, along with the associated changes in cell polarity, directly impacts endocrine cell fate. This proposal aims to characterize cell polarity during pancreatic stratification and resolution, and to test whether the polarity determinants Numb, Numb-like and Par3 are required for pancreatic morphogenesis, MPC specification and endocrine differentiation. Understanding the stepwise processes by which endocrine beta cells acquire their fate and differentiate into functionally mature insulin-producing cells will advance efforts towards cell replacement therapies to treat diabetes, as these steps will be mimicked for in vitro differentiation or regeneration. PUBLIC HEALTH RELEVANCE: Pancreatic islet cells are essential regulators of blood glucose homeostasis, a process required for life that is defective in patients with diseases such as diabetes. Islet cells, including insulin-producing beta cells, arise from multipotent progenitor cells (MPCs) within the early developing pancreas. Here, we focus on elucidating the role of epithelial cell polarity and 3D architecture on the specification of MPCs, as we have found that embryonic pancreatic epithelium undergoes an unusual transient cellular rearrangement (stratification) and loss of cell polarity. Understanding the steps underlying islet cell formation applies directly to efforts at creating new insulin-producing beta cells for replacement therapy in diabetics.