Although diverse actin network architectures found inside the cell have been individually reconstituted outside of the cell, how different types of actin architectures reorganize under applied forces is not entirely understood. Recently, bottom-up reconstitution has enabled studies where dynamic and phenotypic characteristics of various actin networks can be recreated in an isolated cell-like environment. Here, by creating a giant unilamellar vesicle (GUV)-based cell model encapsulating actin networks, we investigate how actin networks rearrange in response to localized stresses applied by micropipette aspiration. We reconstitute actin bundles and branched bundles in GUVs separately and mechanically perturb them. Interestingly, we find that, when aspirated, protrusive actin bundles that are otherwise randomly oriented in the GUV lumen collapse and align along the axis of the micropipette. However, when branched bundles are aspirated, the network remains intact and outside of the pipette while the GUV membrane is aspirated into the micropipette. These results reveal distinct responses in the rearrangement of actin networks in a network architecture-dependent manner when subjected to physical forces.

中文翻译：

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GUV 限制的肌动蛋白网络响应微移液器抽吸的重排

尽管细胞内发现的多种肌动蛋白网络结构已在细胞外单独重建，但不同类型的肌动蛋白结构在外力作用下如何重组尚不完全清楚。最近，自下而上的重建使得研究能够在孤立的类细胞环境中重建各种肌动蛋白网络的动态和表型特征。在这里，通过创建一个封装肌动蛋白网络的基于巨型单层囊泡（GUV）的细胞模型，我们研究了肌动蛋白网络如何重新排列以响应微移液器抽吸施加的局部应力。我们分别在 GUV 中重建肌动蛋白束和分支束，并对它们进行机械扰动。有趣的是，我们发现，当被抽吸时，在 GUV 腔中随机定向的突出肌动蛋白束会塌陷并沿微移液管的轴对齐。然而，当抽吸分支束时，网络保持完整并位于移液器外部，而 GUV 膜被抽吸到微量移液器中。这些结果揭示了当受到物理力时，肌动蛋白网络以依赖于网络架构的方式重排的不同反应。