Stutchbury Ben, Atherton Paul, Tsang Ricky, Wang De-Yao, Ballestrem Christoph
Wellcome Trust Centre for Cell-Matrix Research, University of Manchester, Manchester M13 9PT, England, UK.
Wellcome Trust Centre for Cell-Matrix Research, University of Manchester, Manchester M13 9PT, England, UK
J Cell Sci. 2017 May 1;130(9):1612-1624. doi: 10.1242/jcs.195362. Epub 2017 Mar 16.
Focal adhesions (FAs) are macromolecular complexes that regulate cell adhesion and mechanotransduction. By performing fluorescence recovery after photobleaching (FRAP) and fluorescence loss after photoactivation (FLAP) experiments, we found that the mobility of core FA proteins correlates with their function. Structural proteins such as tensin, talin and vinculin are significantly less mobile in FAs than signaling proteins such as FAK (also known as PTK2) and paxillin. The mobilities of the structural proteins are directly influenced by substrate stiffness, suggesting that they are involved in sensing the rigidity of the extracellular environment. The turnover rates of FAK and paxillin, as well as kindlin2 (also known as FERMT2), are not influenced by substrate stiffness. By using specific Src and FAK inhibitors, we reveal that force-sensing by vinculin occurs independently of FAK and paxillin phosphorylation. However, their phosphorylation is required for downstream Rac1-driven cellular processes, such as protrusion and cell migration. Overall, we show that the FA is composed of different functional modules that separately control mechanosensing and the cellular mechano-response.
粘着斑（FAs）是调节细胞粘附和机械转导的大分子复合物。通过进行光漂白后荧光恢复（FRAP）和光激活后荧光损失（FLAP）实验，我们发现粘着斑核心蛋白的流动性与其功能相关。诸如张力蛋白、踝蛋白和纽蛋白等结构蛋白在粘着斑中的流动性明显低于诸如粘着斑激酶（也称为PTK2）和桩蛋白等信号蛋白。结构蛋白的流动性直接受底物硬度影响，表明它们参与感知细胞外环境的硬度。粘着斑激酶、桩蛋白以及Kindlin2（也称为FERMT2）的周转速率不受底物硬度影响。通过使用特异性的Src和粘着斑激酶抑制剂，我们揭示纽蛋白的力传感独立于粘着斑激酶和桩蛋白的磷酸化而发生。然而，它们的磷酸化对于下游Rac1驱动的细胞过程（如突起和细胞迁移）是必需的。总体而言，我们表明粘着斑由不同的功能模块组成，这些模块分别控制机械传感和细胞机械反应。
