Resolution of islet and acinar lineages during embryogenesis

用于糖尿病移植治疗的产生胰岛素的β细胞的可再生来源最有可能来自代用细胞的有管理的发展，例如胚胎或成年‘干细胞’。彻底了解控制胚胎胰腺发育的外在形态因素和细胞自主因素将极大地促进这一目标。P48/PTF1A是一种胰腺限制性bHLH转录因子，最初被认为在决定腺泡细胞命运方面具有选择性。最近，P48/PTF1A被证明是形成胰岛和腺泡组织所必需的，而突变在 人类基因会导致永久性新生儿糖尿病(PNDM)。P48在胰腺腺泡细胞中的功能形式是异三聚体PTF1复合体。我们发现，来自成人胰腺的PTF1包括一种常见的E蛋白(E12、E47或Heb)P48和哺乳动物中果蝇SU(H)的同源物Suh-L(又名RBP-JK)。我们已经证明了SU(H)(SuH)的Notch反应哺乳动物同源基因也可以与P48和E蛋白以及它们在进化上保守的果蝇同源基因形成三聚体复合体。人类PNDM无义突变删除了P48的C-末端区域，我们已经证明该区域是与Suh和Suh-L相互作用所必需的，因此不能形成三聚体PTF1复合体。我们认为，含有Suh或Suh-L的PTF1与Notch信号通路协同作用，可能在胰腺器官发生的“二次转变”中控制细胞命运的决定。我们将通过三个具体目标来测试这一点。AIM 1将使用 用遗传学方法检测子宫内不同发育阶段P48的耗竭 发育过程需要P48，并确定直接的P48靶基因。AIMS 2和3将决定P48依赖的过程中哪些也需要Suh或Suh-L，以及这一要求是否如预测的那样包括它们参与PTF1复合体。

Renewable sources of insulin-producing beta-cells for transplantation therapy of diabetes mellitus will most likely derive from the managed development of surrogate cells, such as embryonic or adult 'stem' cells. This goal would be facilitated greatly by a thorough understanding of the extrinsic morphogens and cell-autonomous factors that control embryonic pancreatic development. P48/PTF1A is a pancreas-restricted bHLH transcription factor originally thought to functional selectively in specifying acinar cell fate. Recently P48/PTF1A has been shown to be required for the formation of islet as well as acinar tissue, and mutations in the human gene cause permanent neonatal diabetes mellitus (PNDM). The functional form of P48 in pancreatic acinar cells is the heterotrimeric PTF1 complex. We have discovered that PTF1 from adult pancreas comprises P48, one of the common E proteins (E12, E47 or HEB), and SUH-L (aka RBP-Jk), a mammalian homologue of Drosophila Su(H). We have shown that the Notch-responsive mammalian orthologue of Su(H) (SUH) can also form a trimeric complex with P48 and an E protein and as well as with their evolutionarily conserved Drosophila orthologues. The human PNDM nonsense mutations delete the C-terminal region of P48, which we have shown is required for interactions with SUH and SUH-L, and therefore would not be able to form the trimeric PTF1 complex. We propose that PTF1 containing either SUH or SUH-L and in concert with Notch-signaling may control cell-fate decisions during the 'secondary transition' of pancreatic organogenesis. We will test this through three Specific Aims. Aim 1 will use a genetic approach for depleting P48 at different developmental stages in utero to determine which developmental processes require P48 and to identify direct P48-target genes. Aims 2 and 3 will determine which of the P48-dependent processes also require SUH or SUH-L and whether that requirement includes their participation in a PTF1 complex, as predicted.