Regulation of type II cells in the repair ofalveolar epithelial injury

标题：肺泡上皮损伤修复中II型细胞的调节 摘要 在美国，每年约有20万例急性肺损伤（ALI）和急性呼吸道疾病。 窘迫综合征（ARDS）。损伤的肺泡上皮屏障的修复对于解决 ALI/ARDS。然而，目前缺乏旨在促进修复的靶向疗法。 恢复屏障功能。这个项目的目标是了解信号事件的贡献 内源性肺泡修复过程，并确定潜在的药物靶点，以加速修复。肺泡 内衬有两种类型的上皮细胞：肺泡I型细胞（AT 1）和II型细胞（AT 2）。AT 1覆盖率~95% 由于它们薄而扁平的形状，它们占表面积的70%，并负责血液气体交换。 AT 2具有多种功能，包括分泌表面活性剂，还能够充当祖细胞， 肺损伤后增殖并转化为AT 1，以恢复肺泡上皮屏障。但 负责调节AT 2介导的修复的信号传导事件仍然知之甚少。我们的初步 数据表明在AT 2中需要非典型Notch配体Dlk 1（对于δ样1同源物 AT 1分化。我们发现Dlk 1表达的动态变化与AT 2到AT 1之间存在相关性。 维修期间的过渡。使用在AT 2中特异性破坏Dlk 1的小鼠模型，我们发现， 突变细胞不能分化为AT 1，同时Notch异常升高 信号基于这些数据，我们假设动态调节的Notch信号传导是必不可少的， 对于AT 2的适当祖细胞功能，Dlk 1在AT 2到AT 1的过程中起着重要作用。 通过抑制Notch信号传导，在肺泡修复过程中过渡。我们打算进行以下具体工作： 目的：目的1：验证Dlk 1调节肺泡上皮细胞增殖所需的AT 2到AT 1转换的假设。 修复.我们将确定Dlk 1在恢复上皮屏障完整性和气体交换功能中的作用。 受伤后。我们将定义Dlk 1调节的AT 2到AT 1转变的详细步骤，并确定因素 Dlk 1的下游和上游。目的2：检验Dlk 1依赖性动态 在AT 2介导的肺泡修复过程中，经典Notch信号通路的调节是必不可少的。 我们将确定AT 2中Notch信号活性在肺泡修复的不同阶段的作用， 研究Dlk 1和Notch受体和配体之间的分子相互作用。最后我们将 研究通过引入Dlk 1和其他Notch调节因子来改善牙槽骨修复的效果。 将Notch/Dlk 1分子引入肺泡，并将进一步测试Notch/Dlk 1在人AT 2和人iPSC衍生的AT 2中的作用。 在这些研究的结论，我们将填补了一个重要的知识空白， 牙槽修复的潜在机制。我们相信，这些研究将导致发现治疗 目标是加速肺部修复，预防因恢复不当而导致的慢性病理状况。

Title: Regulation of type II cells in the repair of alveolar epithelial injury ABSTRACT Each year in the United States, there are ~ 200,000 cases of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) . Repair of the injured alveolar epithelial barrier is essential for the resolution of ALI/ARDS. However, there is currently a lack of targeted therapies aimed at promoting the repair of the epithelium to restore barrier function. The goal of this project is to understand the signaling events contributing to the endogenous alveolar repair process and identify potential drug targets to accelerate repair. Lung alveoli are lined with two types of epithelial cells: Alveolar Type I cells (AT1) and Type II cells (AT2). AT1 cover ~95% of the surface area because of their thin and squamous shape and are responsible for blood-gas exchange. AT2 have multiple functions including the secretion of surfactant and are also able to act as progenitor cells, proliferating and converting to AT1 after lung injury to restore the alveolar epithelial barrier. However, the signaling events responsible for regulating AT2-mediated repair remain poorly understood. Our preliminary data demonstrated the requirement of a non-canonical Notch ligand Dlk1 (For delta-like 1 homolog) in the AT2 to AT1 differentiation. We found that a dynamic change in Dlk1 expression is correlated with the AT2 to AT1 transition during repair. Using a mouse model in which Dlk1 was specifically disrupted in AT2, we found that the mutant cells were unable to differentiate into AT1 and at mean time had abnormally elevated Notch signaling. Based on these data, we hypothesize that dynamically regulated Notch signaling is essential for the proper progenitor function of AT2 and that Dlk1 plays an essential role in the AT2 to AT1 transition during alveolar repair by inhibiting Notch signaling. We intend to pursue the following specific aims: Aim 1: To test the hypothesis that Dlk1 regulates the AT2 to AT1 transition required for alveolar repair. We will determine the function of Dlk1 in restoring epithelial barrier integrity and gas-exchange function post-injury. We will define the detailed steps in the Dlk1 regulated AT2 to AT1 transition and identifying factors downstream and upstream of Dlk1. Aim 2: To test the hypothesis that the Dlk1-dependent dynamic regulation of the canonical Notch signaling pathway is essential during AT2-mediated alveolar repair. We will determine the role of Notch signaling activity in AT2 at different phases of alveolar repair and investigate the molecular interactions between Dlk1 and Notch receptors and ligands. Finally, we will investigate the effects of improving alveolar repair through the introduction of Dlk1 and other Notch-regulating molecules into alveoli and will further test the roles of Notch/Dlk1 in human AT2 and human iPSC derived AT2. At the conclusion of these studies, we will have filled an important gap in knowledge about the molecular mechanisms underlying alveolar repair. We believe that these studies will lead to the discovery of therapeutic targets to accelerate lung repair and prevent chronic pathological conditions resulting from improper recovery.