Regulation of exocrine pancreas formation

描述（由申请人提供）：胰腺是一个由内分泌、外分泌和导管上皮室组成的复合腺体，在代谢功能和消化活动的调节中起核心作用。与这些胰腺区室相关的功能障碍分别导致糖尿病、胰腺炎和胰腺癌。尽管它们的功能各不相同，但所有的胰腺细胞类型都起源于起源于前肠内胚层的共同祖细胞群。近年来，我们对启动腹侧和背侧胰腺原基形成和分化的环境信号的理解取得了重大进展。此外，Pdx1和Ptf1a已被确定为两个关键的调节因子，它们共同决定了这些原基内胰腺多能祖细胞的命运规范。最近，Foxa1和Foxa2已被证明对胰腺原基的生长和分化以及Pdx1的调节至关重要。除了这些因素外，关于胰腺程序从前肠内胚层开始的分子调控知之甚少。此外，尽管大量对胰岛的形成、分化和发育至关重要的转录因子已被表征，但对外分泌胰腺的形成和发育知之甚少。在这里提出的研究中，我们将研究两个Gata因子家族成员Gata4和Gata6在胰腺原基规范的调节和外分泌胰腺的发育和分化中的作用。我们使用Gata4和Gata6的条件敲除等位基因的初步数据表明，它们在这些调节过程中具有部分冗余功能。此外，我们提出Gata蛋白可能与FoxA蛋白协同调控Pdx1， Gata4可能与Ptf1a协同调控外分泌特异性基因转录。我们打算探索Gata4和Gata6在早期胰腺形成和外分泌分化中的各自作用，具体目的如下：在specific aim 1中，我们将利用Sox9+和Pdx1+胰腺原基中的Gata基因的条件基因消融，结合遗传谱系追踪，表征Gata介导的胰腺原基形成调控。在具体目标2中，我们将研究Gata因子在外分泌细胞发育中的各自作用。在Specific aim 3中，我们将通过探索Gata4与Ptf1a或Gata4与Foxa2之间的遗传和物理相互作用，并确定它们各自在调节胰腺基因表达和发育中的合作活动，来研究Gata4在胰腺特异性基因表达中的分子作用。我们还将使用全局ChIP-Seq和RNA-Seq分析来鉴定胰腺中由Gata4和/或Gata6调控的一组基因。

DESCRIPTION (provided by applicant): The pancreas is a compound gland comprised of endocrine, exocrine and ductal epithelial compartments that play central roles in the regulation of metabolic functions and digestive activities. Dysfunctions associated with these compartments of the pancreas lead to diabetes, pancreatitis and pancreatic cancer, respectively. Despite their diverse functions, all of the pancreatic cell-types arise from a common progenitor population derived from the foregut endoderm. In recent years, significant advances have been made in our understanding of the environmental signals that initiate the formation and differentiation of the ventral and dorsal pancreatic primordia. Furthermore, Pdx1 and Ptf1a have been identified as two key regulatory factors that cooperate to determine the fate specification of the pancreatic multipotent progenitor cells within these primordia. More recently, Foxa1 and Foxa2 have been shown to be essential for the outgrowth and differentiation of the pancreatic primoridia and the regulation of Pdx1. Beyond these factors, little is known about the molecular regulation of the initiation of the pancreatic program from the foregut endoderm. In addition, although a large number of transcription factors that are essential for pancreatic islet specification, differentiation and development have been characterized, little is known about the specification and development of the exocrine pancreas. In the studies proposed here, we will investigate the roles of two Gata factor family members, Gata4 and Gata6, in the regulation of pancreatic primordia specification and in the development and differentiation of the exocrine pancreas. Our preliminary data using conditional knockout alleles of Gata4 and Gata6 suggest they have partially redundant functions in these regulatory processes. Furthermore, we propose that the Gata proteins may cooperate with the FoxA proteins in the regulation of Pdx1, and Gata4 may cooperate with Ptf1a in the regulation of exocrine- specific gene transcription. We intend to explore the respective roles of Gata4 and Gata6 in early pancreas formation and exocrine differentiation in the following specific aims: In Specific aim 1 we will characterize Gata-mediated regulation of pancreatic primordia formation using conditional gene ablation of the Gata genes in the Sox9+ and Pdx1+ pancreatic primordia, combined with genetic lineage tracing. In Specific aim 2 we will investigate the respective roles of the Gata factors in exocrine cell development. In Specific aim 3 we will investigate the molecular role of Gata4 in pancreas- specific gene expression by exploring genetic and physical interactions between Gata4 and Ptf1a or Gata4 and Foxa2 and determining their respective cooperative activities in regulating pancreas gene expression and development. We will also use global ChIP-Seq and RNA-Seq analysis to identify the set of genes regulated by Gata4 and/or Gata6 in the pancreas. PUBLIC HEALTH RELEVANCE: The pancreas is a compound gland comprised of endocrine, exocrine and ductal epithelial compartments that play central roles in the regulation of metabolic functions and digestive activities. Dysfunctions associated with these compartments of the pancreas lead to diabetes, pancreatitis and pancreatic cancer, respectively. The studies proposed here will identify and characterize the primary regulatory pathways that contribute to the formation and function of the pancreas, especially the exocrine pancreas, to improve treatment and tissue replacement therapies of pancreatic diseases.