We used particle-based computer simulations to study the emergent properties of the actomyosin cytoskeleton. Our model accounted for biophysical interactions between filamentous actin and non-muscle myosin II and was motivated by recent experiments demonstrating that spatial regulation of myosin activity is required for fibroblasts responding to spatial gradients of platelet derived growth factor (PDGF) to undergo chemotaxis. Our simulations revealed the spontaneous formation of actin asters, consistent with the punctate actin structures observed in chemotacting fibroblasts. We performed a systematic analysis of model parameters to identify biochemical steps in myosin activity that significantly affect aster formation and performed simulations in which model parameter values vary spatially to investigate how the model responds to chemical gradients. Interestingly, spatial variations in motor stiffness generated time-dependent behavior of the actomyosin network, in which actin asters continued to spontaneously form and dissociate in different regions of the gradient. Our results should serve as a guide for future experimental investigations.

中文翻译：

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化学梯度存在下肌动球蛋白网络的新兴时空动力学。


我们使用基于粒子的计算机模拟来研究肌动球蛋白细胞骨架的新兴特性。我们的模型解释了丝状肌动蛋白和非肌肉肌球蛋白 II 之间的生物物理相互作用，并且受到最近实验的启发，该实验表明，肌球蛋白活性的空间调节是成纤维细胞响应血小板衍生生长因子 (PDGF) 的空间梯度以经历趋化性所必需的。我们的模拟揭示了肌动蛋白紫苑的自发形成，与在趋化成纤维细胞中观察到的点状肌动蛋白结构一致。我们对模型参数进行了系统分析，以确定显着影响紫苑形成的肌球蛋白活性的生化步骤，并进行了模型参数值空间变化的模拟，以研究模型如何响应化学梯度。有趣的是，运动刚度的空间变化产生了肌动球蛋白网络的时间依赖性行为，其中肌动蛋白紫苑继续在梯度的不同区域自发形成和解离。我们的结果应该作为未来实验研究的指南。