Kashiwabara Tomoka, Fukuyama Tatsuya, Maeda Yusuke T
Department of Chemical Engineering, Kyoto University, Nishi-kyoku, Kyoto, 615-8510, Japan.
Sci Rep. 2024 Dec 28;14(1):31339. doi: 10.1038/s41598-024-82864-z.
The actomyosin cytoskeleton, a protein assembly comprising actin fibers and the myosin molecular motor, drives various cellular dynamics through contractile force generation at high densities. However, the relationship between the density dependence of the actomyosin cytoskeleton and force-controlled ordered structure remains poorly understood. In this study, we measured contraction-driven flow generation by varying the concentration of cell extracts containing the actomyosin cytoskeleton and associated nucleation factors. We observed continuous actin flow toward the center at a critical actomyosin density in cell-sized droplets. The actin flow exhibited an emergent oscillation in which the tracer advection in the bulk solution periodically changed in a stop-and-go fashion. In the vicinity of the actomyosin density where oscillatory dynamics occur, the velocity of tracer particle motion decreases with actomyosin density but exhibits superdiffusive motion. Furthermore, the increase or decrease in myosin activity causes the oscillatory flow generation to become irregular, indicating that the density-dependent flow generation of actomyosin is driven by an interplay between actin density and myosin force generation.
肌动球蛋白细胞骨架是一种由肌动蛋白纤维和肌球蛋白分子马达组成的蛋白质组装体，通过在高密度下产生收缩力来驱动各种细胞动力学过程。然而，肌动球蛋白细胞骨架的密度依赖性与力控有序结构之间的关系仍知之甚少。在本研究中，我们通过改变含有肌动球蛋白细胞骨架和相关成核因子的细胞提取物浓度，测量了收缩驱动的流动产生。我们在细胞大小的液滴中观察到，在临界肌动球蛋白密度下，肌动蛋白持续向中心流动。肌动蛋白流表现出一种涌现振荡，其中本体溶液中的示踪剂平流以停停走走的方式周期性变化。在发生振荡动力学的肌动球蛋白密度附近，示踪粒子运动的速度随肌动球蛋白密度降低，但表现出超扩散运动。此外，肌球蛋白活性的增加或降低会导致振荡流的产生变得不规则，这表明肌动球蛋白的密度依赖性流动产生是由肌动蛋白密度和肌球蛋白力产生之间的相互作用驱动的。
