Transcriptional Regulators of Exocrine Pancreatic Development

描述(由申请人提供)：拟议研究的目标是确定胰腺腺泡的发育程序。成熟的、有功能的腺泡是由腺泡细胞组成的，腺泡细胞围绕着一种特殊形式的夹层导管(中央腺泡细胞)和近端连接的导管(夹层导管)。我们认为，这三种细胞类型作为一个单一的发育单位产生于共同的前体细胞类型，即胚胎胰腺的末梢小管细胞。该模型基于新的标志物的使用，这些标志物揭示了成熟腺泡的发育中间体，其基因表达边界表明具有特定功能的离散发育间隔。为了检验这一模型，我们将通过生化和遗传分析来定义两个关键的转录调控因子Ptf1a和Nr5a2的作用。在胰腺器官发生过程中，Ptf1a在两个时间波中表达：在胰腺萌芽开始时和在多能前体细胞和新生腺泡细胞的次级过渡期间处于超诱导水平，在那里它似乎控制着分化。我们将确定在腺泡发育开始时重新激活Ptf1a基因表达的发育信号和转录因子。我们最近发现，Nr5a2在胰腺发育过程中是腺泡形成所必需的，并且是PTF1a的直接靶标。目的1将确定核受体NR5A2控制腺泡发育早期的调节机制。目的2通过鉴定介导Ptf1a活性的DNA结合转录因子来确定转录增强子的调节特性，并确定在胚胎发育和腺泡正常发育过程中哪些因子是调节Ptf1a表达所必需的。目的3将确定Wnt和Notch发育信号在胚胎发育过程中整合到Ptf1a基因转录激活中的方式。公共卫生相关性：胰腺炎和胰腺癌是胰腺的常见疾病。通过了解外分泌胰腺正常发育的控制，我们希望有助于帮助因胰腺炎而严重受损的胰腺再生的治疗，或者找到在不损害身体其他细胞的情况下阻止来自外分泌胰腺的癌细胞生长的方法。

DESCRIPTION (provided by applicant): The goal of the proposed research is to define the developmental program for the pancreatic acinus. A mature, functional acinus is composed of acinar cells, which surround a specialized form of intercalated duct (the centroacinar cells), and the proximal connecting duct (the intercalated duct). We propose that these three cell-types arise as a single developmental unit from a common progenitor cell-type, the terminal tubule cell of the embryonic pancreas. This model is based on the use of new markers that reveal a developmental intermediate reminiscent of the mature acinus, with gene expression boundaries that suggest discrete developmental compartments with specific functions. To examine this model we will define the roles of two key transcriptional regulators, Ptf1a and Nr5a2, through biochemical and genetic analyses. Ptf1a is expressed in two temporal waves during pancreatic organogenesis: at the onset of pancreatic budding and then at super-induced levels during the secondary transition in multipotent precursor cells and nascent acinar cells, where it appears to control differentiation. We will determine the developmental signals and transcription factors that reactivate the expression of the Ptf1a gene for the beginning of acinar development. We have recently shown that Nr5a2 is required during pancreatic development specifically for the formation of acini and is a direct target of PTF1a. Aim 1 will determine the regulatory mechanisms whereby the nuclear receptor NR5A2 controls the early stage of acinar development. Aim 2 will define the regulatory properties of the transcriptional enhancer that reactivates Ptf1a expression in newly forming acinar cells by identifying DNA-binding transcription factors that mediate the activity of the enhancer and determine which of these factors are required for the regulation of Ptf1a expression during embryogenesis and for normal acinar development. Aim 3 will determine the manner in which Wnt and Notch developmental signal are integrated into transcriptional activation of the Ptf1a gene during embryonic development. PUBLIC HEALTH RELEVANCE: Pancreatitis and pancreatic cancer are common diseases of the pancreas. By understanding the control of normal development of the exocrine pancreas we hope to contribute to therapies that may help a pancreas badly damaged by pancreatitis to regenerate, or to identify ways to stop the growth of cancer cells derived from the exocrine pancreas without damaging other cells of the body.