Cell migration is one of the most important processes in which the cytoskeleton plays a main role. The cytoskeleton network is formed by tubulin microtubules, actin filaments, and intermediate filaments (IFs). While the structure and functions of the two aforementioned proteins have been extensively investigated during the last decades, vimentin IFs structure and their role in cell migration and adhesion remain unclear. Here, we investigated polarity determination in rat fibroblasts with either a knocked out vim gene or with a mutation that blocks filament formation on the stage of unit‐length filaments (ULFs). Structured illumination microscopy has demonstrated the difference in the morphology of IFs in wild‐type fibroblasts and of ULFs in mutant fibroblasts. We have developed an approach to measure cell stiffness separately on the trailing and leading edges using atomic force microscopy. Young's modulus values on the leading and trailing edge of migrating rat fibroblasts differ approximately by two times, being larger on the leading edge. The knockout of the vim gene leads to having comparable values of Young's moduli on both edges. Vimentin‐null cells change the direction of migration more frequently than those expressing wild‐type or mutated vimentin. Our results have shown the principle role of vimentin, not only in the form of IFs, but also as ULFs, in the determination of the polarity and the directionality of fibroblast migration.

中文翻译：

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波形蛋白在大鼠成纤维细胞定向迁移中的作用。

细胞迁移是细胞骨架发挥主要作用的最重要过程之一。细胞骨架网络由微管蛋白微管，肌动蛋白丝和中间丝（IF）形成。尽管在过去的几十年中已广泛研究了上述两种蛋白质的结构和功能，但波形蛋白IFs的结构及其在细胞迁移和粘附中的作用仍不清楚。在这里，我们调查了敲除的vim在大鼠成纤维细胞中的极性测定基因或突变，可阻止单位长度细丝（ULF）阶段的细丝形成。结构照明显微镜已证明野生型成纤维细胞中的IFs和突变型成纤维细胞中的ULF形态上的差异。我们已经开发出一种使用原子力显微镜在后缘和前缘分别测量细胞刚度的方法。迁移的大鼠成纤维细胞的前缘和后缘的杨氏模量值相差大约两倍，在前缘处更大。vim的敲除基因导致在两个边缘上具有可比的杨氏模量值。与表达野生型或突变波形蛋白的细胞相比，波形蛋白零细胞更频繁地改变迁移方向。我们的研究结果表明波形蛋白在确定成纤维细胞迁移的极性和方向性时，不仅以IFs形式而且以ULF形式发挥了重要作用。