Mechanobiology of Epithelial Monolayers under Shear Loading

细胞之间的机械相互作用支配着生命的基本过程。然而，我们对这些机械效应的了解还不够多，无法解释我们已经知道的多细胞生物学、组织发育和疾病进展中的许多重要问题，这些问题依赖于细胞间力。细胞间附着(粘连)的维持和周转对于细胞如何在器官的不同部分之间形成屏障至关重要。黏附对伤口愈合很重要，细胞间黏附的破坏也是癌症转移的前兆。器官形成、伤口愈合和癌症转移涉及大变形和力的产生，然而，细胞黏附的动态调节机制、细胞如何相互滑动或剪切，或者细胞-细胞黏附如何在机械载荷下发挥作用尚不清楚。这项研究的目标是了解组织如何分布并对通过细胞-细胞连接传递的剪切力做出反应。该项目将测试剪切如何改变集体细胞行为和细胞结构的重组。这些变化与细胞的生物力学特性有关，并最终调节组织的完整性、屏障功能和动态平衡。研究成果将被纳入基础工程和生物课程的教学单元，并在我们的实验室内发展本科生的研究经验。PIs积极参与为教师和未被充分代表的学生提供的社区外展和研究经验。这项研究将定制的微型制造细胞培养平台与力感应和位移驱动与机械分析和细胞生物学方法(如药物抑制剂和基因敲除细胞系)相结合。我们研究了外加和细胞产生的力如何动态地改变集体细胞的行为，以响应剪切破坏。生理发育表现出缓慢的变形，而损伤发生在较快的时间尺度上，因此我们检验了集体细胞机械反应不仅取决于载荷和组织刚性，而且取决于施加的载荷速率的观点。我们将测试这种观点，即动态的细胞-细胞黏附是由具有力和速率依赖性的蛋白质捕获键控制的。这项工作将为上皮组织的机械操作和观察提供新的平台技术，并测试跨细胞-细胞粘连和细胞骨架的力转移和细胞间通信的新模型。在这项工作中获得的见解将增加我们对上皮稳态的理解，上皮稳态是每个器官系统正常屏障功能的基础。

Mechanical interactions between cells govern the basic processes of life. We don't understand these mechanical effects enough, however, to explain many of the important questions in multicellular biology, tissue development, and disease progression that we already know are dependent on intercellular forces. Maintenance and turnover of the attachments between cells (adhesions) is critical to how cells can form a barrier between different parts of organs. Adhesion is important to wound healing, and also disruption of cell-cell adhesion is a precursor to cancer metastasis. Organ formation, wound healing and cancer metastasis involve large deformations and force generation, yet the mechanisms underlying the dynamic regulation of cell adhesions, how cells slide or shear past one another, or how cell-cell adhesions function under mechanical loading are not yet understood. The research goal is to understand how tissues distribute and respond to shear force transmitted through cell-cell junctions. The project will test how shear modifies collective cell behavior and reorganization of cellular architecture. Such changes are coupled to the biomechanical properties of cells and ultimately regulate tissue integrity, barrier functions and homeostasis. The research results will be incorporated into modules for teaching basic Engineering and Biology courses, and the development of undergraduate research experiences within our laboratories. The PIs actively participate in community outreach and research experiences for teachers and under-represented students.This research combines custom micro-fabricated cell culture platforms with force-sensing and displacement-actuation with mechanical analyses and cell biological methods such as pharmacological inhibitors and knockout cell lines. We study how externally applied and cell-generated forces dynamically modify collective cell behavior in response to shear disruption. Physiological development exhibits slow deformations while injury occurs on a faster timescale, thus we test the idea that collective cell mechanoresponse depends not only on load and tissue rigidity, but also on the applied loading rate. We will test the idea that dynamic cell-cell adhesion is governed by protein catch bonds with force- and rate-dependence. This work will deliver new platform technologies for mechanical manipulation and observation of epithelial tissues and test new models of force transfer and cell-cell communications across cell-cell adhesions and the cytoskeleton. Insights gained in this work will increase our understanding of epithelial homeostasis which underlies normal barrier function in each organ system.