Active multistage coarsening of actin networks driven by myosin motors
Active multistage coarsening of actin networks driven by myosin motors
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DOI：
10.1073/pnas.1016616108
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发表时间：
2011-06-07
影响因子：
11.1
通讯作者：
Koenderink, Gijsje H.
中科院分区：
文献类型：
--
作者：
Soares e Silva, Marina;Depken, Martin;Koenderink, Gijsje H.
在细胞中，许多重要的过程涉及肌球蛋白驱动的运动，积极重塑肌动蛋白细胞骨架和改变细胞形状。在这里，我们研究肌球蛋白电机的集体行动如何组织肌动蛋白丝收缩结构在一个简化的模型系统缺乏生化调节。我们表明，这种自组织发生通过一个积极的多级粗化过程。首先，马达通过沿着肌动蛋白网络结构移动并随后聚结而形成密集的焦点。然后，这些病灶在它们周围的壳中聚集肌动蛋白丝。这些肌动球蛋白冷凝物最终由于马达驱动的聚结而聚集。我们建议，这种多级聚集的物理起源是肌动蛋白丝的高度不对称的负载响应：它们可以支持大的张力，但很容易在皮牛顿压缩载荷下屈曲。由于电机产生的力远远超过了这个阈值，因此在连接的肌动蛋白网络上诱导了屈曲，以抵抗电机驱动的细丝滑动。我们展示了这种屈曲如何引起肌动蛋白壳在肌球蛋白病灶周围的积累，以及随后病灶聚结成超聚集体。这种新的物理机制为在体内观察到的无序凝聚肌动球蛋白状态的形成和收缩动力学提供了解释。
In cells, many vital processes involve myosin-driven motility that actively remodels the actin cytoskeleton and changes cell shape. Here we study how the collective action of myosin motors organizes actin filaments into contractile structures in a simplified model system devoid of biochemical regulation. We show that this self-organization occurs through an active multistage coarsening process. First, motors form dense foci by moving along the actin network structure followed by coalescence. Then the foci accumulate actin filaments in a shell around them. These actomyosin condensates eventually cluster due to motor-driven coalescence. We propose that the physical origin of this multistage aggregation is the highly asymmetric load response of actin filaments: they can support large tensions but buckle easily under piconewton compressive loads. Because the motor-generated forces well exceed this threshold, buckling is induced on the connected actin network that resists motor-driven filament sliding. We show how this buckling can give rise to the accumulation of actin shells around myosin foci and subsequent coalescence of foci into superaggregates. This new physical mechanism provides an explanation for the formation and contractile dynamics of disordered condensed actomyosin states observed in vivo.