Mechanosensitivity of Membrane-Actin Cortex Adhesion

由人类或动物细胞产生或施加于人类或动物细胞的物理力涉及几乎所有基本的细胞功能，包括分裂、形状控制、体积和内部压力控制、分化和迁移以及细胞死亡。这些力必须穿过细胞表面，细胞表面由外面的薄脂膜和里面的机械坚韧的生物聚合物网络-肌动蛋白皮层组成。细胞细致地感知和调节这些力量。就像把帐篷的织物绑在支撑框架上的带子是监测风对帐篷影响的最佳位置一样，细胞中力感应机制的主要位置也是肌动蛋白皮层和脂质膜之间的界面。单细胞如何对力作出反应并产生自己的力对于生物体中的大规模动力学非常重要，例如组织和器官发育，癌症进展和转移，伤口愈合和组织再生。然而，细胞如何感知和响应力在很大程度上仍然是未知的。在这个项目中，该团队将开发和使用一套创新的生物传感器来研究一种重要的膜肌动蛋白连接蛋白ezrin，它被认为是调节干细胞分化和细胞迁移的蛋白，并与癌症进展有关。研究人员将使用传感器来探测蛋白质积累的位置，它可以处于什么样的构象，以及当细胞被物理操纵时它所经历的力。研究人员将联合收割机将这些分子探针的结果与我们对细胞表面大尺度力学的了解相结合，并使用激光束、磁性粒子和弹性微杠杆进行微机械探测。计算建模将被用来模拟ezrin动力学和解释这些实验的结果。这项工作开发了一个创新的概念，将细胞膜和底层机械骨架之间界面上的蛋白质视为一种感官机制，提供控制细胞行为的关键信号。这项研究旨在发现重要的分子参与者，并确定它们如何与整个细胞的大规模机制联系在一起。该项目还推动了技术创新，因为它将提供一套新的生物传感器，可以探测蛋白质所经历的定位，构象和分子力，可以观察到并直接与标准荧光显微镜进行比较。细胞机械传感是生命系统物理学的核心部分，新的见解将对基础细胞和发育生物学以及生物技术和医学产生广泛的影响。机械感测和机械调节与再生医学和各种突出的人类病理学（包括癌症和纤维化）特别相关。通过将分子工程与细胞生物物理学和理论建模相结合，该项目将为培训在这一跨学科领域工作的未来科学家和工程师提供新的方法。通过教育和公众宣传，该研究将吸引来自不同社区的新一代年轻科学家，并激励他们参与生命系统物理学这一广泛领域的研究。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Physical forces generated by, or applied to, human or animal cells are involved in almost every fundamental cellular function, including division, shape control, volume and internal pressure control, differentiation, and migration, as well as cell death. These forces must pass through the surface of the cell, which consists of a thin lipid membrane on the outside and a mechanically tough biopolymer network, the actin cortex, on the inside. Cells meticulously sense and regulate these forces. In the same way that the straps that tie the fabric of a tent to its supporting frame would be the best place to monitor what the wind is doing to the tent, the prime location for force-sensing machinery in the cell is at the interface between the actin cortex and the lipid membrane. How single cells react to forces and produce their own is important for large-scale dynamics in living organisms, such as tissue and organ development, cancer progression and metastasis, wound healing, and tissue regeneration. However, it remains largely unknown how cells sense and respond to forces.In this project, the team will develop and use a suite of innovative biosensors to study a prominent membrane actin linker protein, ezrin, which is known to regulate stem cell differentiation and cell migration and is implicated in cancer progression. The investigators will use the sensors to probe where the protein accumulates, what conformations it can be in, and what forces it experiences as cells are physically manipulated. The investigators will combine the results from these molecular probes with what we know about the larger-scale mechanics of the cell surface and use manipulation with laser beams, magnetic particles, and elastic micro-cantilevers for micromechanical probing. Computational modeling will be used to simulate ezrin kinetics and interpret the results of these experiments. This work develops an innovative concept, considering the proteins at the interface between the cell membrane and the underlying mechanical skeleton as a sensory machinery supplying crucial signals to control cell behavior. The research aims to discover the important molecular players and determine how they tie into the larger-scale mechanics of the whole cell. The project also drives technical innovation in that it will provide a new suite of biosensors that probe the localization, conformation, and molecular force experienced by a protein that can be observed and directly compared with standard fluorescence microscopy.Cellular mechanosensing is a central part of the physics of living systems, and new insights will have a broad impact on fundamental cell and developmental biology as well as biotechnology and medicine. Mechanosensing and mechanoregulation are particularly relevant for regenerative medicine and for various prominent human pathologies, including cancer and fibrosis. By combining molecular engineering with cell biophysics and theoretical modeling, the project will provide new ways of training future scientists and engineers working in this interdisciplinary area at all levels. Through educational and public outreach, the research will engage new generations of young scientists from diverse communities and stimulate them to participate in research in the broad area of the physics of living systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.