The intermediate filament protein vimentin performs an essential role in cytoskeletal interplay and dynamics, mechanosensing and cellular stress responses. In pathology, vimentin is a key player in tumorigenesis, fibrosis and infection. Vimentin filaments undergo distinct and versatile reorganizations, and behave as redox sensors. The vimentin monomer possesses a central α-helical rod domain flanked by N- and C-terminal low complexity domains. Interactions between this type of domains play an important function in the formation of phase-separated biomolecular condensates, which in turn are critical for the organization of cellular components. Here we show that several oxidants, including hydrogen peroxide and diamide, elicit the remodeling of vimentin filaments into small particles. Oxidative stress elicited by diamide induces a fast dissociation of filaments into circular, motile dots, which requires the presence of the single vimentin cysteine residue, C328. This effect is reversible, and filament reassembly can occur within minutes of oxidant removal. Diamide-elicited vimentin droplets recover fluorescence after photobleaching. Moreover, fusion of cells expressing differentially tagged vimentin allows the detection of dots positive for both tags, indicating that vimentin dots merge upon cell fusion. The aliphatic alcohol 1,6-hexanediol, known to alter interactions between low complexity domains, readily dissolves diamide-elicited vimentin dots at low concentrations, in a C328 dependent manner, and hampers reassembly. Taken together, these results indicate that vimentin oxidation promotes a fast and reversible filament remodeling into biomolecular condensate-like structures, and provide primary evidence of its regulated phase separation. Moreover, we hypothesize that filament to droplet transition could play a protective role against irreversible damage of the vimentin network by oxidative stress.

中文翻译：

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氧化应激引起波形蛋白丝重塑为生物分子凝聚物


中间丝蛋白波形蛋白在细胞骨架相互作用和动力学、机械传感和细胞应激反应中发挥着重要作用。在病理学中，波形蛋白是肿瘤发生、纤维化和感染的关键参与者。波形蛋白丝经历独特且多功能的重组，并充当氧化还原传感器。波形蛋白单体具有中心 α-螺旋杆结构域，两侧是 N 端和 C 端低复杂性结构域。此类结构域之间的相互作用在相分离生物分子凝聚体的形成中发挥着重要作用，而这反过来又对于细胞成分的组织至关重要。在这里，我们展示了几种氧化剂，包括过氧化氢和二酰胺，引起波形蛋白丝重塑成小颗粒。二酰胺引起的氧化应激会导致细丝快速解离成圆形、活动的点，这需要单个波形蛋白半胱氨酸残基 C328 的存在。这种效应是可逆的，并且灯丝在去除氧化剂后几分钟内即可重新组装。二酰胺引发的波形蛋白液滴在光漂白后恢复荧光。此外，表达差异标记波形蛋白的细胞融合可以检测到两个标记呈阳性的点，表明波形蛋白点在细胞融合时合并。已知脂肪醇 1,6-己二醇可以改变低复杂性结构域之间的相互作用，在低浓度下很容易以 C328 依赖性方式溶解二酰胺引发的波形蛋白点，并阻碍重新组装。综上所述，这些结果表明波形蛋白氧化促进快速且可逆的丝重塑为生物分子冷凝样结构，并提供其调节相分离的主要证据。 此外，我们假设丝状到液滴的转变可以发挥保护作用，防止氧化应激对波形蛋白网络造成不可逆的损伤。