Defining epithelial polarity cues that direct cell fate

项目摘要 在小鼠和人类中的许多研究已经确定近端气道基底细胞（BC）是主要的气道上皮细胞。 多能干细胞群，其通过以下方式维持假复层上皮的完整性： 分化为分泌细胞、纤毛细胞和杯状细胞。影响呼吸道上皮的慢性病理 可以带来BC生物学的深刻变化，包括BC衰竭和慢性疾病的功能障碍。 阻塞性肺疾病（COPD）以及囊性肺组织中增殖性BC样人群的出现 纤维化和癌症。肺和气管中的健康管腔上皮细胞表现出明显的顶部-底部极性， 我们发现，失去这种极性会刺激促进异常BC扩张的信号。特别是 我们的观察表明，缺失位于顶端的跨膜蛋白Crumbs 3导致了 转录调节因子雅普和Taz（雅普/Taz）的失调，这已经成为必需的 肺和其他器官中发育和疾病过程的调节剂。我们的初步 观察使我们假设异常的核雅普/Taz启动和维持内在和外在的 在微环境中发出信号，促进BC扩张。分析极性缺陷气道， 揭示了一个有趣的雅普/Taz-神经调节蛋白-1（Nrg 1）-ERBB正反馈信号级联反应， 假设促进BC增殖和自我更新。我们还绘制了 细胞外基质微环境，我们假设刺激不同的整合素中继信号， 促进雅普/Taz活性，以及确定了一种新的间充质细胞群，我们假设 介导这些微环境的变化，以响应异常的上皮极性。我们建议 间充质细胞、细胞外基质和气道上皮细胞之间的相互作用支持异常BC 膨胀是对极性损伤的反应。我们建议研究和靶向细胞内信号介导的 通过促进BC扩增的雅普/Taz（AIM 1）和细胞外基质改变（AIM 2），并进一步确定 间充质串扰如何促成与上皮极性损伤相关的表型（AIM 3）。我们 研究将为气道疾病中BC异常扩张提供重要的分子见解，如果成功， 将揭示潜在的生物标志物和治疗干预或靶向这些不良的途径， 了解的疾病，以及用于体外扩增BC用于未来再生疗法的潜在新方法。

PROJECT SUMMARY Numerous studies in mice and humans have established the proximal airway basal cells (BCs) as the major multipotent stem cell population that maintains the integrity of pseudostratified epithelium through differentiation to secretory, ciliated and goblet cells. Chronic pathologies affecting the respiratory epithelium can bring about profound changes in BC biology, including BC exhaustion and dysfunction in chronic obstructive pulmonary disease (COPD) as well as emergence of proliferative BC-like populations in cystic fibrosis and cancer. Healthy luminal epithelial cells in the lung and trachea exhibit distinct apical-basal polarity, and we have found that loss this polarity stimulates signals that promote aberrant BC expansion. In particular our observations indicate that deletion of apical-localized transmembrane protein Crumbs3 leads to the dysregulation of the transcriptional regulators Yap and Taz (Yap/Taz), which have emerged as essential regulators of developmental and disease processes in the lungs and other organs. Our preliminary observations lead us to hypothesize that aberrant nuclear Yap/Taz initiate and sustain intrinsic and extrinsic signals in a microenvironment that promotes BC expansion. Analyses of polarity defective airways has revealed an interesting Yap/Taz-Neuregulin-1(Nrg1)-ERBB positive feed-back signaling cascade that we hypothesize promotes BC proliferation and self-renewal. We have also mapped notably changes in the extracellular matrix microenvironment that we hypothesize stimulates distinct Integrin-relayed signals that promote Yap/Taz activity, as well as identified a novel mesenchymal cell population that we hypothesize mediates these microenvironment changes in response to aberrant epithelial polarity. We propose that crosstalk between mesenchymal cells, extracellular matrix and the airway epithelium support aberrant BC expansion in response to polarity damage. We propose to study and target the intracellular signals mediated by Yap/Taz (AIM 1) and extracellular matrix alterations (AIM 2) that promote BC expansion, and further define how mesenchymal crosstalk contributes to phenotypes associated with epithelial polarity damage (AIM 3). Our studies will offer important molecular insight into aberrant BC expansion in airway disease, and if successful, will reveal potential biomarkers and avenues for therapeutic intervention or targeting of these poorly understood diseases, and potential new methods for expanding BC ex vivo for future regenerative therapies.