Transduction of the environment in airway epithelium

描述（申请人提供）：机械环境深刻影响肺的结构和功能，从发育中的肺分支形态发生和细胞分化，到成熟器官的生长、损伤和重塑。细胞感知和响应其机械环境的潜在分子机制仍然难以捉摸。最近获得的证据表明，分离气道上皮细胞的细胞间隙在生理负荷下高度变形。这些细胞间隙是假定的涉及表皮生长因子受体（EGFR）及其配体的自分泌信号回路的位置。生理水平的机械应力作用于气道上皮细胞，无论是体外还是原位，通过EGFR通路触发信号。综合这些观察结果，可以得出以下中心假设：机械应力可以通过在动态调节的细胞间隙中运行的自分泌EGFR环的稳态活动来传导。这一假设将在以下三个特定目的中进行验证，使用原代人气道上皮培养：(1)建立上皮细胞间隙中自分泌信号回路的分子成分和组成功能；(2)定义细胞间隙对生理相关负载条件的动态生物物理响应；(3)利用生化和计算工具对中心假设进行检验，然后探讨其在调节mucSAC表达中的生物学作用，mucSAC是各种气道疾病中粘液分泌表型上调的标志。由此产生的见解可以为发生在细胞外空间的机械转导建立一个新的和意想不到的范式，并改变我们对机械力如何在健康和疾病中促进气道生物学的看法。肺在正常（如呼吸）和疾病（如哮喘）状态下受到一系列机械力的影响，影响肺的结构和功能。拟议的研究将探索排列在气道上的细胞如何感知和响应其机械环境的变化。这些研究将为理解和调节肺的机械反应提供一个框架。

DESCRIPTION (provided by applicant): The mechanical environment profoundly influences the structure and function of the lung, from branching morphogenesis and cellular differentiation in the developing lung, to growth, injury, and remodeling of the mature organ. The underlying molecular mechanisms by which cells sense and respond to their mechanical environment remain elusive. Recently obtained evidence demonstrates that the intercellular spaces separating airway epithelial cells are highly deformable under physiological loads. These intercellular spaces are the site of putative autocrine signaling loops involving the epidermal growth factor receptor (EGFR) and its ligands. Physiological levels of mechanical stress applied to airway epithelial cells, both in vitro and in situ, trigger signaling through the EGFR pathway. Integration of these observations leads to the following central hypothesis: mechanical stress can be transduced through the steady-state activity of an autocrine EGFR loop operating in a dynamically regulated intercellular space. This hypothesis will be tested in the following three specific aims using primary human airway epithelial cultures: (1) establish the molecular components and constitutive functionality of the autocrine signaling loop in the epithelial intercellular space; (2) define the dynamic biophysical response of the intercellular space to physiologically relevant loading conditions; and (3) use biochemical and computational tools to test the central hypothesis, then explore its biological role in modulating the expression of mucSAC, a marker of the mucus secretory phenotype upregulated in various airway disorders. The resulting insights could establish a new and unanticipated paradigm for mechanotransduction occurring in the extracellular space, and change our view of how mechanical forces contribute to the biology of the airways in health and disease. The lung experiences a range of mechanical forces during normal (e.g. breathing) and disease (e.g. asthma) conditions, influencing lung structure and function. The proposed studies will explore how the cells that line the airways sense and respond to changes in their mechanical environment. These studies will provide a framework for understanding and modulating mechanical responses in the lung.