Lung specification and induction in foregut endoderm

描述(由申请人提供)： 我们建议研究决定时间和地点的早期监管事件 前肠内胚层被指定为肺，并形成芽。在.期间 早期发育，内皮细胞从腹侧前肠启动一个基因 划定未来甲状腺领域的表达程序， 肺、肝和胰腺。一旦指定了内胚层，芽的形成就是 已启动。关于内胚层何时被确定为 肺，哪些转录因子在萌发之前指导着肺的规范， 以及来自中胚层的可扩散信号如何调节空间和时间 肺原基的分化。我们和其他人已经证明了 维甲酸(RA)和成纤维细胞生长因子(FGF)的信号转导 对于原发肺芽形态发生来说是必不可少的。然而，目前还不清楚是否 RA和成纤维细胞生长因子在发育过程中调节内胚层的规格，或者它们如何 信号与前肠中活跃的其他信号通路相互作用。我们的 目标是识别和表征与肺相关的转录因子。 肺芽前规范(目标1)，研究RA和成纤维细胞生长因子的作用 前肠基因表达和肺芽诱导中的信号转导(目标2)，研究 类风湿因子、成纤维细胞生长因子与生物相关性的相互作用 在目标1(目标3)中确定。为了实现这些目标，我们将定义 激光捕捉前部肺野的分子边界 显微切割和实时定量聚合酶链式反应。我们将使用cDNA阵列来 确定表征预期区域的转录因子 阿龙。体内足迹将被用来确定肺基因 启动子在启动之前用转录因子启动 器官发生。这些研究将与一种新的体外系统相结合 允许对前肠和肺芽进行分析和实验操作 在其形成的最初阶段。该系统将用于评估 维甲酸和成纤维细胞生长因子在早期发挥的作用 肺形成的步骤。

DESCRIPTION (provided by applicant): We propose to study the early regulatory events that determine when and where the foregut endoderm is specified to become lung and to form buds. During early development, endodermal cells from the ventral foregut start a gene expression program that demarcates the territories of the future thyroid, lung, liver and pancreas. Once the endoderm is specified, bud formation is initiated. Little is known about when the endoderm is determined to become lung, which transcription factors direct lung specification prior to budding, and how diffusible signals from the mesoderm regulate the spatial and temporal differentiation of the lung primordium. We and others have shown that signaling by retinoic acid (RA) and fibroblast growth factor (FGF) is essential for primary lung bud morphogenesis. However, it is unclear whether RA and FGF regulate endoderm specification during development or how their signals interact with other signaling pathways active in the foregut. Our goals are to identify and characterize transcription factors involved in lung specification before the lung buds (Aim 1), to study the role of RA and FGF signaling in foregut gene expression and lung bud induction (Aim 2), to study interactions between the biological relevance of RA, FGF, and the factors identified in Aim 1 (Aim 3). To accomplish these goals we will define the molecular boundaries of the foregut lung field using laser capture microdissection, and quantitative real-time PCR. We will use cDNA arrays to identify transcription factors that characterize the region of the prospective lung. In vivo footprinting will be used to determine whether lung gene promoters are primed with transcription factors prior to initiation of organogenesis. These studies will be coupled with a new in vitro system that allows analysis and experimental manipulation of the foregut and lung bud during its initial stages of formation. This system will be used to assess the role that retinoids and fibroblast growth factors play in the earliest steps of lung formation.