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。小鼠最大的气道和所有人类传导气道都衬有假复层上皮，其由大致相等数量的分泌细胞（Clara）、纤毛细胞和基底细胞以及稀疏的神经内分泌细胞组成。这些上皮细胞的丰度、分布和功能在使人衰弱的肺部疾病如慢性哮喘、囊性纤维化和癌症中被破坏。我们实验室最近的证据表明，基底细胞自我更新，并产生分化的克拉拉和纤毛细胞在体内超过14周，并在体外至少三代。因此，作为祖细胞群体，基底细胞具有调节整个呼吸道上皮组成的潜力。此外，鉴定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疗法至关重要。通过将长期遗传谱系追踪与共聚焦显微镜以及与干细胞专家的合作相结合，该提案的具体目标1将测试一个假设，即居住在高度血管化的小生境中的一个基底细胞子集在很长一段时间内自我更新。在特定目标2中，将使用一种新的试验来检验基底细胞龛的组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，IL 13是一种已知在慢性哮喘中改变上皮结构和功能的细胞因子，在不存在其他细胞类型（例如基质、免疫细胞）的情况下，在该测定中影响许多基底细胞行为。我们将利用这种检测方法和转基因小鼠品系来检测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型效应物，并且这些发现将使用小鼠模型与生命联系起来。除了提供细胞生物学，肺（病理）生物学和干细胞生物学的多学科培训外，这些数据还将为祖细胞行为对健康和疾病的贡献提供新的见解。

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.