Cell Biology of Airway Epithelial Basal Cell Progenitors

描述(申请人提供)：将氧气输送到肺部进行气体交换的呼吸道(即气管、支气管和细支气管)对人类生活至关重要。小鼠最大的呼吸道和所有人类的传导呼吸道都有一层假复层上皮，由数量大致相等的分泌物(Clara)、纤毛、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、分布和功能在诸如慢性哮喘、囊性纤维化和癌症等衰弱的肺部疾病中被破坏。我们实验室的最新证据表明，在体内14周内，基底细胞可以自我更新并产生分化的Clara和纤毛细胞，体外至少可以传三代。因此，作为一个祖细胞群体，基底细胞具有调节整个呼吸道上皮细胞组成的潜力。此外，识别能够长期自我更新和分化的种群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，这项提议的具体目标1将检验这一假设，即居住在高度血管化的利基环境中的一部分基底细胞可以在非常长的时间内自我更新。在具体目标2中，将使用一种新的分析方法来检验这一假设，即基础细胞生态位的组成部分调节其细胞生物学、自我更新和分化。初步数据显示，IL13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，在缺乏其他细胞类型(如间质、免疫细胞)的情况下，在本实验中影响许多基本细胞行为。我们将利用这一实验和转基因小鼠品系来测试BMP信号在维持呼吸道上皮细胞动态平衡中的作用。从长远来看，这项测试将被用于识别基础细胞行为的新效应者，这些发现将与使用小鼠模型的生活相关。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，这些数据还将为祖细胞行为对健康和疾病的贡献提供新的线索。

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.