Defining epithelial polarity cues that direct cell fate

项目总结 许多对小鼠和人类的研究证实，近端呼吸道基底细胞(BCS)是主要的 维持假复层上皮完整性的多潜能干细胞群通过 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 可引起BC生物学的深刻变化，包括BC衰竭和慢性 阻塞性肺疾病(COPD)和囊性增殖性BC样群的出现 纤维化和癌症。健康的肺和气管的管腔上皮细胞表现出明显的尖底两极， 我们发现，失去这一极性会刺激促进BC反常膨胀的信号。特别是 我们的观察表明，顶端定位的跨膜蛋白Crums3的缺失导致 转录调控基因Yap和Taz(Yap/Taz)的失调，这两个基因已经成为必不可少的 肺和其他器官的发育和疾病过程的调节器。我们的预赛 观察结果引导我们假设，异常的核YAP/Taz启动并维持内在和外在的 促进卑诗省扩张的微环境中的信号。极性缺陷呼吸道HAS的分析 揭示了一个有趣的YAP/Taz-NeuRegin-1(Nrg1)-ERBB正反馈信号级联 假设促进BC的增殖和自我更新。我们还绘制了显著的变化 我们假设的细胞外基质微环境刺激不同的整合素传递的信号， 促进YAP/Taz活性，以及确定一个我们假设的新的间充质细胞群 调节这些微环境对异常上皮极性的反应。我们建议 间充质细胞、细胞外基质和呼吸道上皮之间的串扰支持异常BC 对极性损坏的响应而膨胀。我们建议研究和定位细胞内信号介导的 通过YAP/Taz(AIM 1)和细胞外基质改变(AIM 2)促进BC扩张，并进一步定义 间充质串扰如何影响与上皮极性损伤相关的表型(目标3)。我们的 研究将为呼吸道疾病中BC的异常扩张提供重要的分子洞察力，如果成功， 将揭示潜在的生物标记物和治疗干预或靶向这些不良的途径 了解的疾病，和潜在的新方法扩大BC体外为未来的再生疗法。

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.