REGULATION OF AIRWAY PROGENITOR CELL FATE IN DEVELOPMENT AND REGENERATION

描述（由申请人提供）：本修订申请的总体目标是研究气道祖细胞在发育过程中和成年后再生过程中获得并平衡其不同细胞表型的机制。更具体地说，我们将重点关注Notch的作用和Ascl 1在发育中气道细胞命运选择中的调节，以及损伤后气道重新填充的情况。 我们最近报道，Notch信号在胚胎气道上皮细胞是必不可少的，建立平衡的分泌和非分泌细胞的命运。Notch信号传导的破坏阻止Clara细胞形成，并导致气道中神经内分泌细胞和纤毛细胞过度增殖。Notch如何影响细胞命运选择？哪些配体对这一过程至关重要，它们是否驱动气道中的任何特定谱系程序？对萘损伤的成年小鼠的研究表明，对该化合物具有抗性的克拉拉细胞群能够产生平衡比例的分泌细胞和纤毛细胞。目前尚不清楚这是如何实现的。我们有初步证据表明Notch可能调节这一过程。在此，我们建议在三个具体目标中解决这些问题。目标1：研究平衡上皮细胞表型的机制，着眼于不同Notch配体在其中Jagged或Delta配体失活的小鼠遗传模型中的作用;目的2：使用体内和气道上皮培养模型表征Ascl 1表达细胞的谱系和命运及其在邻近气道上皮中的影响，以及目的3：研究Notch介导的细胞命运选择在再生气道中的机制，使用损伤修复的萘模型以及药理学和遗传学方法来抑制Notch。

DESCRIPTION (provided by applicant): The overall goal of this revised application is to investigate mechanisms by which airway progenitor cells acquire and balance their different cell phenotypes during development and during regeneration in adult life. More specifically, we will focus on the role of Notch and its regulation by Ascl1 in the selection of cell fates in developing airways and when airways are repopulated after injury. We have recently reported that Notch signaling in the embryonic airway epithelium is essential for establishing the balance of secretory and non-secretory cell fates. Disruption of Notch signaling prevents Clara cells from forming and results in airways overpopulated by neuroendocrine and ciliated cells. How does Notch influence cell fate selection? Which ligands are critical for this process and do they drive any specific lineage program in the airways? Studies in adult mice injured by Naphthalene suggest that a population of Clara cells resistant to this compound is able to give rise to a balanced proportion of secretory and ciliated cells. How this is achieved is currently unknown. We have preliminary evidence that Notch may regulate this process. Here we propose to address these issues in three specific aims. Aim 1: Study mechanisms that balance epithelial cell phenotypes looking at the role of different Notch ligands in mouse genetic models in which Jagged or Delta ligands were inactivated; Aim 2: Characterize lineage and fate of Ascl1-expressing cells and their influence in the neighbor airway epithelium using in vivo and airway epithelial culture models, and, Aim 3: Investigate mechanisms of Notch-mediated cell fate choice in regenerating airways using a Naphthalene model of injury repair and pharmacologic and genetic approaches to inactivate Notch.