Physical Approaches for Probing the Mechanical Properties of Intermediate Filaments

摘要 细胞必须支持力量，必须施加力量，并且必须对力量做出反应。所有这些行为从根本上说是 建立在细胞的机械性能上，这在很大程度上由内部的三个丝状网络决定 细胞骨架、肌动蛋白、微管和中间丝(IF)。而肌动蛋白和微管广泛存在 被认为是决定电池机械性能的关键部件，并得到了很好的研究， 人们越来越认识到中间长丝的重要性。例如，没有振动的单元格 中间纤维在施加小剪切力时要弱得多，也更容易断裂。 在大小上与血液流动中遇到的相当；此外，它们的稳定性要差得多， 细胞核和细胞器位置不稳定，更容易移动。波形蛋白IF的存在 网络机械地稳定细胞；然而，它们必须与其他丝状网络协同工作。 本计划项目的总体目标是阐明Vimentin IF网络的角色以及它如何 与其他丝状网络协同工作，以确定细胞的机械性能。我们会 通过研究含有和不含有马达蛋白的重组混合网络来分离 在存在其他网络的情况下IF网络的机制。这些研究的结果将被比较 对生长在平面衬底上的细胞的机械行为，包括孤立层和融合层，以及对细胞 与波形蛋白相关的疾病。最终，我们将建立新的系统，使细胞特性的研究成为可能 在模拟活体环境的三维网络中生长。在这项研究中获得的知识将 建立对波形蛋白在细胞力学中的作用的基础性科学理解，这最终将 为波形蛋白相关疾病的治疗发展提供指导。

Abstract Cell must support forces, must exert forces, and must respond to forces. All these behaviors are fundamentally built on mechanical properties of the cells, which are largely determined by three filamentous networks within the cytoskeleton, actin, microtubules, and intermediate filaments (IF). While actin and microtubules are widely cited as the crucial components determining the mechanical properties of the cells and are well studied, the importance of intermediate filaments is increasingly being recognized. For example, cells without vimentin intermediate filaments are much weaker and more susceptible to break up upon application of small shear forces comparable in magnitude to those encountered in blood flow; moreover, they are much less stable, with the nucleus and organelles lacking positional stability and being easier to move. The presence of vimentin IF networks mechanically stabilize cells; however, they must work in concert with the other filamentous networks. The overarching goal of this Program Project is to elucidate the roles of the vimentin IF network and how it operates in concert with other filamentous networks to determine the mechanical properties of cells. We will accomplish this through studies of reconstituted mixed networks with and without motor proteins to isolate the mechanics of the IF networks in the presence of the other networks. The results of these studies will be compared to the mechanical behavior of cells grown on flat substrates, both isolated and in confluent layers, and for cells from vimentin-related diseases. Ultimately, we will build new systems to enable studies of the properties of cells grown in three-dimensional networks that mimic environments in vivo. The knowledge gained in this study will establish foundational scientific understanding of roles of vimentin IFs in cell mechanics, which will ultimately provide guidance to the development of treatments for vimentin related diseases.