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。本项目旨在探讨损伤后气道上皮正常恢复的机制。目前气道上皮细胞再生的范例是一个一步的过程，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，我们建立了一个新的模型的基础上，我们发现，转录因子Myb定义了一个重要的中间阶段，从祖细胞的发展专门的细胞。我们的研究结果表明，Myb+P63-细胞是必不可少的纤毛和分泌型气道细胞类型的分化。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。在我们的小鼠肺损伤模型和慢性阻塞性肺病患者的气道中，Myb增加。在小鼠和人气道上皮细胞的原代培养物中耗尽Myb消除了分化。因此，我们产生了气道上皮细胞特异性Myb缺失的小鼠，同样发现未能产生纤毛分泌细胞。Myb缺陷和足够的细胞之间的全基因组基因表达比较确定了纤毛和分泌细胞分化的程序，以及Sox 2水平的降低。验证数据表明，Sox 2在P63-气道上皮细胞中减少，表明对Sox 2的Myb依赖性需求。总之，这些发现使我们假设Myb调节分化的气道上皮细胞的维持、修复和再生所必需的程序。使用Myb靶向缺陷小鼠和原代培养模型，我们建议研究（1）使用小鼠损伤模型的Myb依赖性细胞修复和再生决定因素，以及（2）识别气道上皮分化的Myb依赖性分子程序。这些研究将为了解气道疾病的发病机制建立一个新的模型，并将关键因素确定为修复治疗的靶点。

 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.