Esue Osigwe, Carson Ashley A, Tseng Yiider, Wirtz Denis
Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA.
J Biol Chem. 2006 Oct 13;281(41):30393-9. doi: 10.1074/jbc.M605452200. Epub 2006 Aug 9.
The assembly and organization of the three major eukaryotic cytoskeleton proteins, actin, microtubules, and intermediate filaments, are highly interdependent. Through evolution, cells have developed specialized multifunctional proteins that mediate the cross-linking of these cytoskeleton filament networks. Here we test the hypothesis that two of these filamentous proteins, F-actin and vimentin filament, can interact directly, i.e. in the absence of auxiliary proteins. Through quantitative rheological studies, we find that a mixture of vimentin/actin filament network features a significantly higher stiffness than that of networks containing only actin filaments or only vimentin filaments. Maximum inter-filament interaction occurs at a vimentin/actin molar ratio of 3 to 1. Mixed networks of actin and tailless vimentin filaments show low mechanical stiffness and much weaker inter-filament interactions. Together with the fact that cells featuring prominent vimentin and actin networks are much stiffer than their counterparts lacking an organized actin or vimentin network, these results suggest that actin and vimentin filaments can interact directly through the tail domain of vimentin and that these inter-filament interactions may contribute to the overall mechanical integrity of cells and mediate cytoskeletal cross-talk.
真核生物的三种主要细胞骨架蛋白，即肌动蛋白、微管和中间丝，其组装和组织高度相互依赖。在进化过程中，细胞已发展出专门的多功能蛋白，介导这些细胞骨架丝网络的交联。在此，我们检验这样一个假说：这两种丝状蛋白，即F-肌动蛋白和波形蛋白丝，能够直接相互作用，即在没有辅助蛋白的情况下。通过定量流变学研究，我们发现波形蛋白/肌动蛋白丝网络的混合物具有比仅含肌动蛋白丝或仅含波形蛋白丝的网络显著更高的硬度。最大的丝间相互作用发生在波形蛋白/肌动蛋白摩尔比为3比1时。肌动蛋白和无尾波形蛋白丝的混合网络显示出低机械硬度和弱得多的丝间相互作用。再加上具有突出波形蛋白和肌动蛋白网络的细胞比缺乏有组织的肌动蛋白或波形蛋白网络的对应细胞硬得多这一事实，这些结果表明肌动蛋白和波形蛋白丝可通过波形蛋白的尾部结构域直接相互作用，并且这些丝间相互作用可能有助于细胞的整体机械完整性并介导细胞骨架的串扰。
