Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France.
Institute of Experimental and Clinical Pharmacology and Toxicology, Medical Faculty, University of Freiburg, Freiburg, Germany.
Nat Commun. 2024 Nov 3;15(1):9497. doi: 10.1038/s41467-024-53859-1.
Focal adhesions (FAs) strengthen their link with the actin cytoskeleton to resist force. Talin-vinculin association could reinforce actin anchoring to FAs by controlling actin polymerization. However, the actin polymerization activity of the talin-vinculin complex is not known because it requires the reconstitution of the mechanical and biochemical activation steps that control the association of talin and vinculin. By combining kinetic and binding assays with single actin filament observations in TIRF microscopy, we show that the association of talin and vinculin mutants, mimicking mechanically stretched talin and activated vinculin, triggers a sequential mechanism in which filaments are nucleated, capped and released to elongate. In agreement with these observations, FRAP experiments in cells co-expressing the same constitutive mutants of talin and vinculin revealed accelerated growth of stress fibers. Our findings suggest a versatile mechanism for the regulation of actin assembly in FAs subjected to various combinations of biochemical and mechanical cues.
焦点黏附（FAs）通过加强与肌动蛋白细胞骨架的连接来抵抗外力。粘着斑钙黏蛋白（talin）- 结合蛋白（vinculin）的关联可以通过控制肌动蛋白聚合来加强肌动蛋白在 FAs 中的锚定。然而，由于需要重建控制粘着斑钙黏蛋白（talin）和结合蛋白（vinculin）关联的机械和生化激活步骤，因此 talin-vinculin 复合物的肌动蛋白聚合活性尚不清楚。通过将动力学和结合测定与 TIRF 显微镜中单肌动蛋白丝观察相结合，我们表明，模拟机械拉伸 talin 和激活 vinculin 的 talin 和 vinculin 突变体的关联引发了一个连续的机制，其中细丝被成核、加帽和释放以延长。与这些观察结果一致，在共表达相同组成型突变体的 talin 和 vinculin 的细胞中进行的 FRAP 实验揭示了应力纤维的快速生长。我们的发现表明，在受到各种生化和机械线索组合的 FAs 中，肌动蛋白组装的调节存在一种通用机制。
