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，必须对力量作出反应。所有这些行为从根本上说 建立在细胞的机械特性上，这在很大程度上是由细胞内的三个丝状网络决定的。 细胞骨架、肌动蛋白、微管和中间丝（IF）。虽然肌动蛋白和微管广泛存在于 被认为是决定细胞机械性能的关键成分，并得到了很好的研究， 中间丝的重要性日益被认识到。例如，没有波形蛋白的细胞 中间长丝要弱得多并且在施加小的剪切力时更容易断裂 与血流中遇到的幅度相当;此外，它们的稳定性要差得多， 细胞核和细胞器缺乏位置稳定性，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波形蛋白IF网络的作用，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质。我们将 通过研究有和没有马达蛋白的重组混合网络来分离 在其他网络存在的情况下，IF网络的力学。这些研究的结果将被比较 对于生长在平坦基底上的细胞的机械行为，无论是分离的还是融合的层， 与波形蛋白有关的疾病最终，我们将建立新的系统来研究细胞的特性 在模拟体内环境的三维网络中生长。本研究中获得的知识将 建立对波形蛋白IF在细胞力学中作用的基础科学认识，最终将 为波形蛋白相关疾病的治疗提供指导。

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.