Physical mechanisms of 3D cell motility

项目摘要 细胞通过三维（3D）细胞外基质（ECM）的运动是正常细胞生长的重要组成部分。 生理学和疾病，包括伤口愈合和肿瘤转移。了解细胞如何移动 通过结构多样的3D矩阵将是至关重要的设计治疗旨在控制细胞迁移 在体内在3D迁移过程中，转移性肿瘤细胞和伤口愈合成纤维细胞都面临着转移性肿瘤细胞的转移。 同样的问题：如何有效地移动笨重、僵硬的核。而肌动球蛋白收缩的力量是 对于细胞在3D矩阵中移动其细胞核至关重要，但尚不清楚ECM如何调节它 结构或物理耦合到核。另一层复杂性来自于3D 基质结构可以控制肌动球蛋白收缩性以决定细胞用于移动的突起的类型（即， 迁移可塑性）。通过了解3D ECM的结构如何影响ECM的物理性质， 核和肌动球蛋白收缩，我们的目标是建立一个概念框架，以解释如何和为什么人类 细胞在不同的3D迁移机制之间切换。我们最近发现，人类细胞以一种 线性弹性3D基质依赖于基于整合素的细胞-基质粘附和肌动球蛋白收缩力 把细胞核向前拉，就像一个活塞，从使用低压板状伪足转换到使用高压板状伪足， 叶足突起这个项目将测试对细胞核的机械应力重新编程的假设 细胞内的结构和极性来为细胞核提供动力，从而通过3D矩阵为细胞提供动力。到 为了实现这些目标，我们将联合收割机结合生物物理学和细胞生物学的方法来测量机械应力 并确定细胞骨架所需的离散元件之间的分子连接， 高压三维运动目标1将操纵基质和细胞核的物理结构， 测量细胞组装和激活核活塞机制的能力。这种方法将 确定为什么3D矩阵可以重新编程细胞力的产生，以将细胞切换到压力驱动的3D 迁移目的2将鉴定由3D基质细胞特异性激活的肌动球蛋白机制 相互作用产生压力和管理迁移可塑性。这些实验将清楚地区分 肌动球蛋白丝负责将核活塞从那些对基质反应的细胞中拉出来 通过增加牵引力来提高刚度。目的3将确定波形蛋白中间体 纤维将力传递到细胞核以维持细胞内极化和定向细胞运动。 3D矩阵的狭窄范围。这些新的方法将确定细胞核是否是一个机械传感器 其通过控制肌动球蛋白收缩性和3D细胞迁移模式来响应3D基质结构。 这增强了对定向3D细胞运动和迁移的基本原理的理解。 可塑性将导致新的治疗策略，以控制正常和异常的细胞运动在体内。

Project Summary Cell movement through three-dimensional (3D) extracellular matrix (ECM) is an essential component of normal physiology and disease, including wound healing and tumor metastasis. Understanding how cells move through structurally diverse 3D matrices will be essential to design therapies aimed at controlling cell migration in the body. During 3D migration, both metastatic tumor cells and wound healing fibroblasts are faced with the same problem: how to efficiently move the bulky, stiff nucleus. While the power of actomyosin contractility is essential for cells to move their nuclei in 3D matrices, it is not understood how it is regulated by the ECM structure or physically coupled to the nucleus. An additional layer of complexity comes from the fact that the 3D matrix structure can govern actomyosin contractility to dictate the type of protrusions cells use to move (i.e. migratory plasticity). By understanding how the structure of the 3D ECM affects the physical properties of the nucleus and actomyosin contractility, we aim to create a conceptual framework to explain how and why human cells switch between distinct 3D migration mechanisms. We recently discovered that human cells moving in a linearly elastic 3D matrix rely on integrin-based cell-matrix adhesions and the power of actomyosin contractility to pull the nucleus forward, like a piston, and switch from using low-pressure lamellipodia to high-pressure lobopodial protrusions. This project will test the hypothesis that mechanical stress on the nucleus reprograms intracellular architecture and polarity to power the nucleus, and thereby the cell through 3D matrices. To achieve these goals, we will combine biophysical and cell biology approaches to measure mechanical stress on the nucleus and determine the molecular connections between discreet cytoskeletal elements required for high-pressure 3D motility. Aim 1 will manipulate the physical structures of the matrix and the nucleus and measure the ability of the cells to assemble and activate the nuclear piston mechanism. This approach will establish why the 3D matrix can reprogram cellular force production to switch cells to pressure-driven 3D migration. Aim 2 will identify the actomyosin machinery that is specifically activated by 3D matrix-cell interactions to generate pressure and govern migratory plasticity. These experiments will clearly distinguish the actomyosin filaments responsible for pulling the nuclear piston forward from those that respond to matrix stiffness by increasing traction force. Aim 3 will determine the mechanisms by which vimentin intermediate filaments transmit force to the nucleus to sustain intracellular polarization and directional cell movement in the narrow confines of the 3D matrix. These novel approaches will determine if the nucleus is a mechanosensor that responds to 3D matrix structure by governing actomyosin contractility and the mode of 3D cell migration. This enhanced understanding of the fundamental principles of directional 3D cell motility and migratory plasticity will lead to new therapeutic strategies to control normal and abnormal cell movement in the body.