Department of New Materials and Biosystems, Max Planck Institute for Metals Research, Stuttgart, Germany.
J Phys Condens Matter. 2010 May 19;22(19):194108. doi: 10.1088/0953-8984/22/19/194108. Epub 2010 Apr 26.
Focal adhesions (FAs) are important adhesion sites between eukaryotic cells and the extracellular matrix, their size depending on the locally applied force. To quantitatively study the mechanosensitivity of FAs, we induce their growth and disassembly by varying the distribution of intracellular stress. We present a novel method for micromanipulation of living cells to explore the dynamics of focal adhesion (FA) assembly under force. Fibroblasts are sheared laterally to their adhesion surface with single PDMS micropillars in order to apply laterally stretch or compression to focal adhesions. This allows for measuring the shear force exerted by the micropillar and correlates it with FA length and growth velocity. Furthermore, we analyze the resulting dynamics of FA molecules (paxillin) and compare intensity profiles along FAs before and after the application of external force. The responses of stretched and relaxed FAs differ fundamentally: relaxed and compressed FAs disassemble isotropically and show no length variation while stretched FAs grow unisotropically in the direction of the applied force and show protein influx only at their front.
焦点黏附（FAs）是真核细胞与细胞外基质之间的重要黏附位点，其大小取决于局部施加的力。为了定量研究 FAs 的机械敏感性，我们通过改变细胞内应力的分布来诱导它们的生长和组装。我们提出了一种新的方法来进行活细胞的微操作，以探索在力作用下焦点黏附（FA）组装的动力学。通过单个 PDMS 微柱将成纤维细胞侧向剪切到它们的黏附表面，以向焦点黏附施加侧向拉伸或压缩。这允许测量微柱施加的剪切力，并将其与 FA 长度和生长速度相关联。此外，我们分析了 FA 分子（桩蛋白）的动力学，并比较了施加外力前后 FA 上的强度分布。拉伸和放松的 FA 的响应有根本的不同：放松和压缩的 FA 各向同性地解体，没有长度变化，而拉伸的 FA 则沿作用力方向非均匀地生长，并且只有在其前端才有蛋白质流入。
