Beta-cell differentiation: Role of the smad network

描述（来自申请人摘要的逐字）：使用推定的 “胰腺干细胞”已被认为是一个潜在的来源， 工程β细胞治疗糖尿病。我们发现 胚胎胰腺上皮能够形成三种成分中的每一种， 成熟胰腺（内分泌、腺泡和导管），取决于具体的 细胞外生长环境我们关注细胞外信号， 可能在早期胚胎上皮细胞的正常发育中起作用 因为这些细胞外因子可能具有潜在的 体外工程化产生胰岛素的β细胞的治疗用途 基因改造的必要性。激活素，TGF-β成员 信号分子超家族，对于内分泌分化是重要的 无论是正常发育的胰腺内源性，还是外源性 当添加到培养物中的胰腺细胞或胰腺雏形中时。激活素 在体内具有剂量窗，使得阻断表达，或 组成型表达，两者都产生发育不全的胰岛，而 适当的信号传导产生正常的胰岛。在体外，在胚胎胰腺中，我们 发现中等剂量的激活素是促内分泌的，但高或低， 剂量不是。此外，在类似于胚胎胰腺的细胞系中， 上皮细胞（AR 42 J），激活素单独诱导内分泌分化，但与 凋亡率高。其他细胞因子（HGF或β细胞素）， 然而，激活素阻止细胞凋亡并诱导胰岛素表达。中央 这项拨款提案的假设是，细胞内关键细胞内的变化 激活素信号级联的组分（特别是Smad 2和Smad 3）是 对激活素调节的胰岛素阳性分化至关重要。此外，委员会认为， 然后，HGF调节smad信号传导，从而增强胰岛素阳性细胞。 分化我们希望确定最佳剂量的外源性和/或 内源性激活素和/或HGF在诱导的胰岛素分化方面， 以及最佳胰岛素表达与表达水平的关系 对激活素和HGF信号传导至关重要的smad分子 （smad 2和3）。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来证实表达。在 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导， 将胰腺内分泌祖细胞或干细胞操作为β细胞。

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.