Airway Smooth Muscle Cell Orientation Control by Contractile Torque

描述（由申请人提供）：已经确定贴壁细胞响应于基底的机械不均匀性（包括基底拉伸和材料各向异性）而改变其取向。虽然已知细胞使用其收缩机制来机械感知这些不均匀性，但尚不知道来自底物的机械信号和细胞内收缩力如何合作来控制细胞取向。目前的范式认为，从基板的机械不均匀性是一个先决条件的级联生化和重塑事件，管理细胞到一个新的位置。我们最近的理论研究表明，响应于基板的不均匀性的细胞的重定向和转向可能是由机械机制，甚至调节。这使我们产生了以下新的、机械的和可验证的工作假设：响应于基质的机械不均匀性，细胞骨架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，该机制将细胞转向一个新的方向。因此，本研究的主要目的是研究收缩力矩和细胞重定向之间的关系。为了实现这一点，我们需要新的实验工具来测量收缩扭矩。因此，我们提出两个目标：1。使用细胞映射流变学技术测量细胞在响应于不均匀、静态和动态基底拉伸的细胞重定向期间的收缩扭矩。2.设计一种材料各向异性可变的基底，以测量细胞在基底材料各向异性诱导下的收缩力矩。虽然所提出的工作是任何贴壁细胞的基础，在这里，我们限制注意的问题，气道平滑肌（ASM）细胞的收缩性，机械传感和定位的基板上。这些问题对气道力学至关重要，因为如果合适的话，ASM细胞对气道的收缩是正常气道狭窄的关键。如果成功的话，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中的组织和收缩性的机制的理解。 公共卫生相关性：越来越多的证据表明，气道的微环境可能有助于肺部疾病的发展，如过敏和哮喘的超敏反应，通过改变气道平滑肌细胞的结构和空间组织。本研究将探讨气道平滑肌细胞感知其微环境中的机械变化并通过改变其方向和排列作出反应的物理机制。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.