Cell Biology of Airway Epithelial Basal Cell Progenitors

描述（由申请人提供）：将氧气输送到肺部进行气体交换的气道（即气管、支气管和细支气管）对人类生命至关重要。小鼠的最大气道和所有人类的传导气道都衬有一层假层状上皮，由数量大致相等的分泌细胞（Clara）、纤毛细胞、基底细胞和稀疏的神经内分泌细胞组成。这些上皮细胞的丰度、分布和功能在慢性哮喘、囊性纤维化和癌症等使肺部衰弱的疾病中被破坏。我们实验室最近的证据表明，基底细胞自我更新并在体内产生分化的克拉拉和纤毛细胞超过14周，并在体外至少三次传代。因此，作为一个祖细胞群，基底细胞具有调节整个呼吸道上皮组成的潜力。此外，识别能够长期自我更新和分化的群体对于开发基于细胞的肺部疾病治疗方法至关重要。通过将长期遗传谱系追踪与共聚焦显微镜相结合，并与干细胞专家合作，本提案的特异性目标1将验证一个假设，即居住在高度血管化的生态位中的基底细胞子集在很长一段时间内自我更新。在特异性目标2中，将使用一种新的测定方法来测试基底细胞生态位成分调节其细胞生物学、自我更新和分化的假设。初步数据显示，在缺乏其他细胞类型（如基质细胞、免疫细胞）的情况下，IL13（一种已知能改变慢性哮喘中上皮结构和功能的细胞因子）会影响许多基底细胞的行为。我们将利用该实验和转基因小鼠系来测试Bmp信号在维持气道上皮稳态中的功能。从长远来看，该试验将用于识别基底细胞行为的新效应物，这些发现将通过小鼠模型与生活联系起来。除了提供细胞生物学、肺（病理）生物学和干细胞生物学方面的多学科培训外，这些数据将为祖细胞行为对健康和疾病的贡献提供新的视角。

DESCRIPTION (provided by applicant): Airways (i.e. the trachea, bronchi, and bronchioles) that transport oxygen to the lungs for gas exchange are essential to human life. The largest airways of mice, and all human conducting airways, are lined with a pseudostratified epithelium made up of roughly equal numbers of secretory (Clara), ciliated, and basal cells and sparse neuroendocrine cells. The abundance, distribution, and function of these epithelial cells are disrupted in debilitating lung diseases such as chronic asthma, cystic fibrosis, and cancer. Recent evidence from our lab has shown that basal cells self-renew and generate differentiated Clara and ciliated cells over 14 weeks in vivo and for at least three passages in vitro. Therefore, as a progenitor population, basal cells have the potential to regulate the composition of the whole respiratory epithelium. Moreover, the identification of a population capable of long-term self-renewal and differentiation is critical for the development of cell-based therapies for lung diseases. By combining long-term genetic lineage tracing with confocal microscopy and collaborations with stem cell experts, Specific Aim 1 of this proposal will test the hypothesis that a subset of basal cells, residing in a highly vascularized niche, self-renews over very long periods. In Specific Aim 2, a novel assay will be used to test the hypothesis that components of the basal cell niche modulate their cell biology, self-renewal, and differentiation. Preliminary data has shown that IL13, a cytokine known to alter epithelial structure and function in chronic asthma, affects numerous basal cell behaviors in this assay in the absence of other cell types (e.g. stroma, immune cells). We will exploit this assay and transgenic mouse lines to test the functions of Bmp signaling in the maintenance of airway epithelial homeostasis. In the longer term, this assay will be used to identify novel effectors of basal cell behaviors and these findings will be related back to life using mouse models. In addition to providing multidisciplinary training in cell biology, lung (patho) biology, and stem cell biology, these data will throw new light on the contributions of progenitor cell behaviors to health and disease.