ROLE OF MYB FOR AIRWAY EPITHELIAL CELL DIFFERENTIATION

 描述（由申请人提供）：导致气道上皮细胞分化和更新的途径正在进行深入研究，因为这些程序对于肺损伤后的修复至关重要，并且可能失调导致哮喘和慢性阻塞性气道疾病中的上皮细胞化生。该项目致力于研究损伤后气道上皮正常恢复的机制。当前气道上皮细胞再生的范例是一步过程，其中调节因子将自我更新的 P63 祖细胞引导至分化类型。在这个项目中，我们基于我们的发现建立了一个新模型，即转录因子 Myb 定义了从祖细胞到特化细胞进展的一个重要的中间阶段。我们的研究结果表明，Myb P63-细胞对于纤毛细胞和分泌性气道细胞类型的分化是必需的。 Myb 在肺发育期间和我们的原代培养模型中短暂表达，并且在健康成人肺中不存在。 Myb 在我们的肺损伤小鼠模型和患有慢性阻塞性肺病的个体气道中增加。在小鼠和人气道上皮细胞的原代培养物中耗尽 Myb 会消除分化。因此，我们培育了气道上皮细胞特异性删除 Myb 的小鼠，并且同样发现无法发育纤毛广告分泌细胞。 Myb 缺陷细胞和充足细胞之间的全基因组基因表达比较确定了纤毛细胞和分泌细胞分化的程序以及 Sox2 水平的降低。验证数据表明，P63-气道上皮细胞中的 Sox2 减少，表明对 Sox2 的 Myb 依赖性需求。总之，这些发现使我们推测 Myb 调节对分化气道上皮细胞的维持、修复和再生至关重要的程序。使用 Myb 靶向缺陷小鼠和原代培养模型，我们建议研究（1）使用小鼠损伤模型进行修复和再生的 Myb 依赖性细胞决定因素，以及（2）确定气道上皮分化的 Myb 依赖性分子程序。这些研究将建立一个新模型来了解气道疾病的发病机制，并确定关键要素作为修复治疗的目标。

 DESCRIPTION (provided by applicant): The pathways leading to airway epithelial cell differentiation and renewal are undergoing intense study as these programs are essential for repair following lung injury, and may be dysregulated leading to epithelial cell metaplasia in asthma and chronic obstructive airway disease. This project addresses the mechanism of normal restoration of the airway epithelium after injury. The current paradigm for airway epithelial cell regeneration is a one-step process, whereby regulatory factors direct a self-renewing P63+ progenitor cell to a differentiated type. In this project, we establish a new model based on our finding that the transcription factor Myb defines an essential intermediate stage in the progression from progenitor to specialized cell. Our findings suggest that the Myb+P63- cell is obligatory for the differentiation of a ciliated and secretory airway cell types. Myb is transietly expressed during lung development and in our primary-culture models, and is absent in the healthy adult lung. Myb is increased in our mouse models of lung injury and in airways of individuals with chronic obstructive lung disease. Depleting Myb in primary-culture of mouse and human airway epithelial cells abrogates differentiation. Accordingly, we generated mice with airway epithelial cell-specific deletion of Myb, and likewise found a failure to develop ciliated ad secretory cells. Genome-wide gene expression comparison between Myb deficient and sufficient cells identified programs for ciliated and secretory cell differentiation, and a reductin of Sox2 levels. Validation data demonstrated Sox2 was decreased in P63- airway epithelial cells, suggesting a Myb dependent requirement for Sox2. Together, these findings lead us to hypothesize that Myb regulates a program essential for the maintenance, repair and regeneration of differentiated airway epithelial cells. Using Myb targeted deficient mice and primary culture models, we propose to investigate (1) Myb-dependent cellular determinants for repair and regeneration using mouse injury models, and (2) identify Myb-dependent molecular programs for airway epithelial differentiation. The studies will establish a new model for understanding the pathogenesis of airways disease and define key elements as targets for reparative therapies.