Lung specification and induction in foregut endoderm

描述（由申请人提供）： 我们建议研究决定何时何地的早期监管事件 前肠内胚层被指定为肺并形成芽。期间 在发育早期，来自腹前肠的内胚层细胞启动一个基因， 表达程序，划分未来甲状腺的领土， 肺、肝和胰腺。一旦内胚层被指定，芽的形成就被确定。 启动。关于内胚层何时决定成为 肺，其中转录因子在出芽之前指导肺特化， 以及来自中胚层的可扩散信号如何调节 肺原基的分化。我们和其他人已经证明， 视黄酸（RA）和成纤维细胞生长因子（FGF）的信号传导是 对初级肺芽形态发生至关重要。然而，目前尚不清楚是否 RA和FGF在发育过程中调节内胚层特化或它们如何调节内胚层特化。 信号与前肠中活跃的其它信号通路相互作用。我们 目的是鉴定和表征参与肺损伤的转录因子， 目的1：研究RA和FGF在肺芽前分化中的作用 前肠基因表达和肺芽诱导的信号传导（目的2），以研究 RA、FGF的生物学相关性与以下因素之间的相互作用 目标1（目标3）。为了实现这些目标，我们将定义 利用激光捕获的前肠肺野的分子边界 显微切割和定量实时PCR。我们将使用cDNA阵列 鉴定表征预期的区域的转录因子， 肺。体内足迹法将用于确定肺基因是否 启动子在启动前用转录因子引发， 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 类维生素A和成纤维细胞生长因子在最早期 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.