Motor-driven advection competes with crowding to drive spatiotemporally heterogeneous transport in cytoskeleton composites
Motor-driven advection competes with crowding to drive spatiotemporally heterogeneous transport in cytoskeleton composites
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DOI：
10.3389/fphy.2022.1055441
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发表时间：
2022-05
影响因子：
3.1
通讯作者：
J. Sheung;Jonathan Garamella;Stella K Kahl;Brian Y. Lee;R. McGorty;R. Robertson-Anderson
中科院分区：
文献类型：
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作者：
J. Sheung;Jonathan Garamella;Stella K Kahl;Brian Y. Lee;R. McGorty;R. Robertson-Anderson
细胞骨架——生物聚合物、分子马达和相关结合蛋白的复合网络——是活性物质的典型例子。通过细胞骨架的粒子传输范围可以从异常和异质的亚扩散到超扩散和平流。然而，概括和理解这些在细胞骨架和其他不平衡的软物质系统中普遍存在的特性仍然具有挑战性。在这里，我们将光片显微镜与微分动态显微镜和单粒子追踪相结合，以阐明肌动球蛋白-微管复合材料中的异常和平流运输。我们表明，粒子表现出多模式传输，在可调节的交叉时间尺度上从明显的次扩散过渡到超扩散。令人惊讶的是，虽然较高的肌动球蛋白含量增加了超扩散运输的时间尺度范围，但它也显着增加了短时间尺度下的亚扩散程度，并且通常减慢了运输。相应的位移分布显示出非高斯性、不对称性和非零模式的独特组合，表明定向平流与笼式扩散和跳跃相结合。在更大的时空尺度上，活性复合材料中的粒子表现出超扩散动力学，其缩放指数对改变肌动球蛋白分数具有鲁棒性，这与没有肌动球蛋白的网络中正常但更快的扩散形成鲜明对比。我们的具体结果为活跃细胞骨架系统中非平衡过程、拥挤和异质性之间的相互作用提供了重要的新线索。更一般地说，我们的方法广泛适用于活性物质系统，以阐明跨尺度的传输和动力学。
The cytoskeleton–a composite network of biopolymers, molecular motors, and associated binding proteins–is a paradigmatic example of active matter. Particle transport through the cytoskeleton can range from anomalous and heterogeneous subdiffusion to superdiffusion and advection. Yet, recapitulating and understanding these properties–ubiquitous to the cytoskeleton and other out-of-equilibrium soft matter systems–remains challenging. Here, we combine light sheet microscopy with differential dynamic microscopy and single-particle tracking to elucidate anomalous and advective transport in actomyosin-microtubule composites. We show that particles exhibit multi-mode transport that transitions from pronounced subdiffusion to superdiffusion at tunable crossover timescales. Surprisingly, while higher actomyosin content increases the range of timescales over which transport is superdiffusive, it also markedly increases the degree of subdiffusion at short timescales and generally slows transport. Corresponding displacement distributions display unique combinations of non-Gaussianity, asymmetry, and non-zero modes, indicative of directed advection coupled with caged diffusion and hopping. At larger spatiotemporal scales, particles in active composites exhibit superdiffusive dynamics with scaling exponents that are robust to changing actomyosin fractions, in contrast to normal, yet faster, diffusion in networks without actomyosin. Our specific results shed important new light on the interplay between non-equilibrium processes, crowding and heterogeneity in active cytoskeletal systems. More generally, our approach is broadly applicable to active matter systems to elucidate transport and dynamics across scales.