REGULATION OF AIRWAY PROGENITOR CELL FATE IN DEVELOPMENT AND REGENERATION

描述（由申请人提供）：本次修订申请的总体目标是研究气道祖细胞在发育和成人再生过程中获得和平衡其不同细胞表型的机制。更具体地说，我们将关注Notch及其通过Ascl1调控在气道发育和气道损伤后再生过程中细胞命运选择中的作用。我们最近报道了胚胎气道上皮中的Notch信号对于建立分泌和非分泌细胞命运的平衡至关重要。Notch信号的破坏阻止了Clara细胞的形成，导致气道中神经内分泌细胞和纤毛细胞过多。Notch如何影响细胞命运选择？哪些配体对这个过程至关重要它们是否驱动气道中的特定谱系程序？对受萘损伤的成年小鼠的研究表明，对这种化合物有抵抗力的Clara细胞群体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，我们建议从三个具体目标来解决这些问题。目的1：研究平衡上皮细胞表型的机制，观察不同Notch配体在Jagged或Delta配体失活的小鼠遗传模型中的作用；目的2：利用体内和气道上皮培养模型表征表达ascl1细胞的谱系和命运及其对邻近气道上皮的影响；目的3：利用萘损伤修复模型和药理学和遗传学方法灭活Notch，研究再生气道中Notch介导的细胞命运选择机制。

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.