Abstract

In cells, cytoskeletal filament networks are responsible for cell movement, growth, and division. Filaments in the cytoskeleton are driven and organized by crosslinking molecular motors. In reconstituted cytoskeletal systems, motor activity is responsible for far-from-equilibrium phenomena such as active stress, self-organized flow, and spontaneous nematic defect generation. How microscopic interactions between motors and filaments lead to larger-scale dynamics remains incompletely understood. To build from motor–filament interactions to predict bulk behavior of cytoskeletal systems, more computationally efficient techniques for modeling motor–filament interactions are needed. Here, we derive a coarse-graining hierarchy of explicit and continuum models for crosslinking motors that bind to and walk on filament pairs. We compare the steady-state motor distribution and motor-induced filament motion for the different models and analyze their computational cost. All three models agree well in the limit of fast motor binding kinetics. Evolving a truncated moment expansion of motor density speeds the computation by \(10^3\)–\(10^6\) compared to the explicit or continuous-density simulations, suggesting an approach for more efficient simulation of large networks. These tools facilitate further study of motor–filament networks on micrometer to millimeter length scales.

Graphic abstract

中文翻译：

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具有交联马达的细胞骨架丝的显式和平均场模型的比较

摘要

在细胞中，细胞骨架丝网络负责细胞运动、生长和分裂。细胞骨架中的细丝由交联分子马达驱动和组织。在重组的细胞骨架系统中，运动活动是造成远离平衡现象的原因，例如主动应力、自组织流动和自发向列缺陷产生。电机和细丝之间的微观相互作用如何导致更大规模的动力学仍然不完全清楚。为了从运动-细丝相互作用来预测细胞骨架系统的整体行为，需要更高效的计算技术来模拟运动-细丝相互作用。在这里，我们推导了一个粗粒度层次结构的显式和连续模型，用于交联电机，这些电机结合并在灯丝对上行走。我们比较了不同模型的稳态电机分布和电机引起的灯丝运动，并分析了它们的计算成本。所有三个模型都在快速电机结合动力学的限制上非常一致。发展运动密度的截断力矩扩展可加快计算速度\(10^3\) – \(10^6\)与显式或连续密度模拟相比，提出了一种更有效地模拟大型网络的方法。这些工具有助于进一步研究微米到毫米长度尺度上的电机-灯丝网络。

图形摘要