The cytoskeleton is a complex network of interconnected biopolymers intimately involved in the generation and transmission of forces. Several mechanical properties of microtubules and actin filaments have been extensively explored in cells. In contrast, intermediate filaments (IFs) received comparatively less attention despite their central role in defining cell shape, motility and adhesion during physiological processes as well as in tumor progression. Here, we explored relevant biophysical properties of vimentin IFs in living cells combining confocal microscopy and a filament tracking routine that allows localizing filaments with ~20 nm precision. A Fourier-based analysis showed that IFs curvatures followed a thermal-like behavior characterized by an apparent persistence length (lp*) similar to that measured in aqueous solution. Additionally, we determined that certain perturbations of the cytoskeleton affect lp* and the lateral mobility of IFs as assessed in cells in which either the microtubule dynamic instability was reduced or actin filaments were partially depolymerized. Our results provide relevant clues on how vimentin IFs mechanically couple with microtubules and actin filaments in cells and support a role of this network in the response to mechanical stress.

中文翻译：

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波形蛋白中间丝在活细胞中的表观硬度及其与其他细胞骨架聚合物的关系。

细胞骨架是相互联系的生物聚合物的复杂网络，紧密地参与了力的产生和传递。微管和肌动蛋白丝的几种机械性能已在细胞中进行了广泛探索。相比之下，尽管中间丝（IFs）在定义生理过程中以及肿瘤进程中的细胞形状，运动性和粘附性方面起着核心作用，但它们受到的关注相对较少。在这里，我们结合共聚焦显微镜和细丝跟踪程序探索了波形蛋白IFs在活细胞中的相关生物物理特性，该程序可以使细丝定位为约20 nm精度。基于傅立叶的分析表明，IF曲率遵循类似热的行为，其特征是与水溶液中测得的表观持久性长度（lp *）相似。另外，我们确定，细胞骨架的某些扰动会影响lp *和IF的横向迁移率，如在其中微管动态不稳定性降低或肌动蛋白丝部分解聚的细胞中评估的那样。我们的结果为波形蛋白IFs如何与细胞中的微管和肌动蛋白丝机械偶联提供了线索，并支持了该网络在机械应力响应中的作用。