Molecular and Cellular Basis of Pharyngeal Pouch Development

描述(申请人提供)：面部上皮，包括咽囊，是组织头部发育的重要信号中心。人类出生缺陷(如DiGeorge综合征)中的眼袋形成缺陷会导致面部骨骼、心脏和腺体(例如甲状旁腺和胸腺)的各种发育异常。然而，我们仍然对眼袋形成背后的遗传控制和细胞行为知之甚少。这项建议的长期目标是了解DiGeorge综合征基因TBX1如何与成纤维细胞生长因子和Wnt信号通路相互作用，以精确控制驱动眼袋形成的上皮转变。在这项建议中，我们使用创新的转基因和突变工具在斑马鱼中评估前袋内胚层中发育基因的功能。我们将其与活胚胎中眼袋发育的时间推移成像相结合，这使我们能够了解这些基因如何控制特定的眼袋细胞行为。斑马鱼非常适合这些研究，因为袋子的发育与人类高度保守，但斑马鱼是唯一可以进行高通量转基因研究和单细胞分辨率时间推移成像的脊椎动物系统。这项工作的积极发现将阐明TBX1如何在上游激活Wnt和成纤维细胞生长因子信号级联，从而驱动眼袋的发育。特别是，Wnt途径基因将代表潜在的和/或改变人类出生缺陷的新候选基因，如DiGeorge和Pfeiffer综合征。由于胚胎内胚层的分枝不仅产生囊，还产生肝、胰腺、肺和其他器官，从我们的研究中获得的经验教训也将对理解许多重要内胚层器官的初始形成具有普遍意义。

DESCRIPTION (provided by applicant): Facial epithelia, including the pharyngeal pouches, are important signaling centers that organize development of the head. Defects in pouch formation in human birth defects such as DiGeorge Syndrome result in a variety of developmental abnormalities of the facial skeleton, heart, and glands (e.g. parathyroid and thymus). However, we still know little about the genetic control and cellular behaviors underlying pouch formation. The long-term goal of this proposal is to understand how the DiGeorge Syndrome gene Tbx1 interacts with Fgf and Wnt signaling pathways to precisely control the epithelial transitions that drive pouch formation. In this proposal, we use innovative transgenic and mutant tools in zebrafish to assess the function of developmental genes in the pre-pouch endoderm. We combine this with time-lapse imaging of pouch development in living embryos, which allows us to understand how these genes control specific pouch cell behaviors. Zebrafish is ideally suited for these studies as pouch development is highly conserved with humans, yet zebrafish is the only vertebrate system in which high-throughout transgenic studies and single-cell- resolution time-lapse imaging are practical. Positive findings from this work will elucidate how Tbx1 acts upstream to activate Wnt and Fgf signaling cascades that drive pouch development. In particular, Wnt pathway genes will represent novel candidates for underlying and/or modifying human birth defects such as DiGeorge and Pfeiffer Syndromes. As branching of the embryonic endoderm generates not only pouches but also the liver, pancreas, lung, and other organs, lessons learned from our studies will also have general implications for understanding the initial formation of many important endodermal organs.