ROLE OF MYB FOR AIRWAY EPITHELIAL CELL DIFFERENTIATION

 描述(申请人提供)：导致呼吸道上皮细胞分化和更新的途径正在进行深入的研究，因为这些程序对于肺损伤后的修复是必不可少的，可能会导致哮喘和慢性阻塞性呼吸道疾病中的上皮细胞化生。本项目旨在探讨损伤后呼吸道上皮细胞正常恢复的机制。目前的呼吸道上皮细胞再生模式是一个一步法的过程，即调节因子将自我更新的p63前体细胞导向分化类型。在这个项目中，我们基于我们的发现建立了一个新的模型，即转录因子Myb定义了从祖细胞到特化细胞的过程中必不可少的中间阶段。我们的发现表明，Myb p63-细胞对于纤毛型和分泌型呼吸道细胞的分化是必需的。MYB在肺发育和我们的原代培养模型中瞬时表达，在健康的成人肺中缺失。在我们的小鼠肺损伤模型和慢性阻塞性肺疾病患者的呼吸道中，MYB增加。在小鼠和人的呼吸道上皮细胞的原代培养中，耗尽Myb会取消分化。因此，我们产生了呼吸道上皮细胞特异性Myb缺失的小鼠，同样发现没有发育出纤毛的ad分泌细胞。Myb缺陷细胞和足够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。验证数据显示，SOX2在p63-呼吸道上皮细胞中减少，表明对Sox2的需求依赖于Myb。综上所述，这些发现引导我们假设Myb调控着一个对分化的呼吸道上皮细胞的维持、修复和再生至关重要的程序。利用Myb靶向缺陷小鼠和原代培养模型，我们建议利用小鼠损伤模型来研究(1)依赖Myb的细胞修复和再生决定因素，以及(2)确定依赖Myb的分子程序来促进呼吸道上皮细胞分化。这些研究将为理解呼吸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.