Contractile actomyosin networks are responsible for the production of intracellular forces. There is increasing evidence that bundles of actin filaments form interconnected and interconvertible structures with the rest of the network. In this study, we explored the mechanical impact of these interconnections on the production and distribution of traction forces throughout the cell. By using a combination of hydrogel micropatterning, traction force microscopy and laser photoablation, we measured the relaxation of traction forces in response to local photoablations. Our experimental results and modelling of the mechanical response of the network revealed that bundles were fully embedded along their entire length in a continuous and contractile network of cortical filaments. Moreover, the propagation of the contraction of these bundles throughout the entire cell was dependent on this embedding. In addition, these bundles appeared to originate from the alignment and coalescence of thin and unattached cortical actin filaments from the surrounding mesh.

收缩肌动球蛋白网络负责细胞内力的产生。越来越多的证据表明，肌动蛋白丝束与网络的其余部分形成相互连接和相互转换的结构。在这项研究中，我们探讨了这些互连对整个单元牵引力的产生和分配的机械影响。通过结合使用水凝胶微图案化、牵引力显微镜和激光光消融，我们测量了响应局部光消融的牵引力的松弛。我们的实验结果和网络机械响应模型表明，束沿其整个长度完全嵌入皮质细丝的连续收缩网络中。而且，这些束的收缩在整个细胞中的传播取决于这种嵌入。此外，这些束似乎起源于来自周围网状物的薄且未附着的皮质肌动蛋白丝的排列和聚结。