Beta-cell differentiation: Role of the smad network

描述(逐字摘自申请人的摘要)：推定的用法 “胰腺干细胞”已被认为是一种潜在的 用于糖尿病治疗的工程β细胞。我们发现， 胚胎胰腺上皮能够形成三种元素中的每一种 成熟的胰腺(内分泌、腺泡和导管)，取决于特定的 胞外生长环境。我们一直专注于细胞外信号， 可能在早期胚胎上皮细胞的正常发育中发挥作用 转化为β细胞，因为这种细胞外因子可能具有 体外工程制造胰岛素β细胞的治疗应用 基因改造的必要性。激活素，转化生长因子-β的成员 信号分子超家族，对内分泌分化起重要作用 无论是内源性的正常发育的胰腺，还是外源性的 当添加到培养中的胰腺细胞或胰腺雏形中时。激活素 在体内有一个剂量窗口，这样要么被阻断表达，要么 结构性表达，两者均可产生发育不良的朗格汉斯胰岛，而 正确的信号会产生正常的胰岛。在体外，在胚胎胰腺中，我们 发现中等剂量的激活素是促进内分泌的，但有高或低 剂量不是。此外，在类似胚胎胰腺的细胞系中 上皮细胞(AR42J)，激活素单独诱导内分泌分化，但与 细胞凋亡率高。其他细胞因子(肝细胞生长因子或β细胞蛋白)与 然而，激活素可以防止细胞凋亡并诱导胰岛素表达。中环 这项拨款提案的假设是，关键细胞内的变化 激活素信号级联的组件(特别是Smad2和Smad3)是 对激活素调节的胰岛素阳性分化至关重要。此外， 然后，HGF调节Smad信号，从而增强胰岛素阳性 差异化。我们希望确定外源性和/或 内源性激活素和/或肝细胞生长因子在诱导胰岛素分化方面的作用 以及最适胰岛素表达与表达水平的关系 对激活素和HGF信号转导至关重要的Smad分子 (Smad2和Smad3)。此外，这些Smad分子对胰岛素的重要性 将通过反义和转基因策略确认表达。在……里面 通过这种方式，我们希望使用这种细胞内信号作为优化的指南 胰腺内分泌祖细胞或干细胞转化为p细胞的操作。

DESCRIPTION (Verbatim from Applicant's Abstract): The use of putative "pancreatic stem cells" has been recognized as a potential source for engineering beta cells for the cure of diabetes mellitus. We found that the embryonic pancreatic epithelium is able to form each of the three elements of the mature pancreas (endocrine, acinar, and ductal), depending on the specific extracellular growth environment. We have focused on extracellular signals that may play a role in the normal development of early embryonic epithelial cells into beta cells, since such extracellular factors may have potential therapeutic use for engineering insulin-producing beta cells in vitro without the need for genetic modiftcation. Activins, members of the TGF-beta superfamily of signaling molecules, are important for endocrine differentiation both endogenously in the normal developing pancreas, as well as exogenously when added to pancreatic cells or pancreatic rudiments in culture. Activins have a dosage window in vivo such that either blocked expression, or constitutive expression, both yield hypoplastic islets of Langerhans, whereas proper signaling yields normal islets. In vitro, in embryonic pancreas, we found that intermediate doses of activin are pro-endocrine, but high or low doses are not. Further, in cell lines resembling embryonic pancreatic epithelium (AR42J), activin alone induces endocrine differentiation, but with a high rate of apoptosis. Additional cytokines (HGF or betacellulin) with the activin, however, prevent apoptosis and induce insulin-expression. The central hypothesis of this grant proposal is that changes in key intracellular components of the activin signaling cascade (specifically smad2 and smad3) are critical to activin-regulated insulin-positive differentiation. Furthermore, HGF then modulates smad signaling and thus enhances insulin-positive differentiation. We wish to determine the optimal doses of exogenous and/or endogenous activin and/or HGF in terms of induced insulin differentiation, as well as the relationship of optimal insulin expression to the expression level of smad molecules that are critically important to activin and HGF signaling (smad2 and 3). Furthermore, the importance of these smad molecules to insulin expression will be confirmed through antisense and transgenic strategies. In this way, we hope to use this intracellular signaling as a guide to optimizing the manipulation of pancreatic endocrine progenitor or stem cells into p-cells.