Airway Smooth Muscle Cell Orientation Control by Contractile Torque

描述(由申请人提供)：众所周知，贴壁细胞会改变它们的取向，以响应衬底的机械不均匀，包括衬底拉伸和材料各向异性。虽然已知细胞使用其收缩机械来机械感知这些不均匀，但还不知道来自底物的机械信号和细胞内的收缩力量如何协作来控制细胞的取向。目前的模式认为，来自底物的机械不一致性是一系列生化和重塑事件的先决条件，这些事件将细胞控制到一个新的位置。我们最近的理论研究表明，细胞对底物不均匀的重新定位和转向可能受机械机制的支配，甚至是受机械机制的调控。这就引出了以下新颖的、机械的和可测试的工作假说：为了响应底物的机械不一致性，细胞骨架的收缩应力通过一个简单的物理机制--即收缩扭矩--决定细胞的方向，从而引导细胞走向一个新的方向。因此，这项研究的主要目的是研究收缩扭矩和细胞重定向之间的关系。要做到这一点，我们需要新的实验工具来测量收缩扭矩。因此，我们提出了两个目标：1.使用细胞映射流变学技术测量细胞在非均匀、静态和动态基质拉伸时重定向过程中的收缩扭矩。2.设计一种材料各向同性可变的基板，以测量细胞重定向过程中的收缩扭矩，以响应基板的材料各向异性。虽然拟议的工作是任何贴壁细胞的基础，但这里我们仅限于对呼吸道平滑肌(ASM)细胞收缩、机械传感和在基质上定位的问题的关注。这些问题对呼吸道力学至关重要，因为如果合适的话，ASM细胞对呼吸道的收缩是正常气道狭窄的关键。如果成功，这项研究将促进我们对机械微环境决定ASM细胞在其自然栖息地的组织和收缩能力的机制的理解。 公共卫生相关性：越来越多的证据表明，呼吸道微环境可能通过改变呼吸道平滑肌细胞的结构和空间组织，促进肺部疾病的发展，如对过敏和哮喘的过敏。本研究将探讨气道平滑肌细胞感知微环境中的机械变化并通过改变其取向和排列来做出反应的物理机制。如果成功，这项研究将建立管理气道平滑肌细胞空间组织的物理原理，并确定未来治疗干预的潜在靶点。

DESCRIPTION (provided by applicant): It is well established that adherent cells change their orientation in response to mechanical non- uniformities of the substrate, including substrate stretching and material anisotropy. While it is known that cells use their contractile machinery to mechanosense these nonuniformities, it is not known how mechanical signals from the substrate and intracellular contractile forces cooperate to govern cell orientation. The current paradigm holds that mechanical nonuniformities from the substrate are a precondition for a cascade of biochemical and remodeling events that govern cell to a new position. Our recent theoretical study suggests that reorientation and steering of the cell in response to substrate nonuniformities may be governed and even regulated by mechanical mechanisms. This led us to the following novel, mechanistic, and testable working hypothesis: In response to mechanical nonuniformities of the substrate, the cytoskeletal contractile stress dictates orientation of the cell via a simple physical mechanism - namely the contractile torque - that steers the cell towards a new orientation. The main goal of this study is therefore to investigate the relationship between the contractile torque and cell reorientation. To accomplish this, we need new experimental tools for measuring the contractile torque. Thus, we propose two aims: 1. To measure the contractile torque during cell reorientation in response to nonuniform, static and dynamic, substrate stretching using the cell mapping rheometry technique. 2. To design a substrate with alterable material isotropy in order to measure the contractile torque during cell reorientation in response to induced material anisotropy of the substrate. Although the proposed work is fundamental to any adherent cells, here we limit attention to the questions of airway smooth muscle (ASM) cell contractility, mechanosensing and positioning on the substrate. These questions are crucial to airway mechanics because, if appropriate, constriction of airways by ASM cells is the key to normal airway narrowing. If successful, this investigation will advance our understanding of the mechanisms by which the mechanical microenvironment dictates organization and contractility of ASM cells in their natural habitat. PUBLIC HEALTH RELEVANCE: A growing body of evidence indicates that the microenvironment of the airways may contribute to the development of pulmonary diseases, such as hypersensitivity to allergy and asthma, by altering structure and spatial organization of airway smooth muscle cells. The present study will investigate the physical mechanisms by which airway smooth muscle cells sense mechanical changes in their microenvironment and respond by altering their orientation and alignment. If successful, this study will establish physical principles that govern airway smooth muscle cell spatial organization and identify potential targets for therapeutic intervention in the future.