Fast and slow dynamics of the cytoskeleton
Fast and slow dynamics of the cytoskeleton
复制标题
DOI：
10.1038/nmat1685
复制
发表时间：
2006-08-01
期刊：
影响因子：
41.2
通讯作者：
Fredberg, Jeffrey J.
中科院分区：
文献类型：
--
作者：
Deng, Linhong;Trepat, Xavier;Fredberg, Jeffrey J.
细胞骨架的材料模数(CSK)影响广泛的细胞功能(1-3)。从重组的F-肌动蛋白凝胶中有大量证据表明，存在一个以普适指数3/4的频率调节模数的制度。这种行为是起源的熵，可归因于热力驱动的半柔性聚合物的波动(4-7)，但这种熵效应是否与CSK的弹性有关并不是一个明显的先验证据。在这里，我们证明了在活细胞中存在这样一种机制，但仅在高频下存在。快事件以类似于半柔性聚合物动力学的方式随频率扩展，但慢事件以系统小于3/4的非通用指数进行扩展，并且可能更符合软玻璃区域(8，9)。这些发现强烈地表明，在较小的时间尺度上，弹性来自半柔性细丝网络的熵涨落，而在较长的时间尺度上，来自不同起源的缓慢(软玻璃样)动力学占优势。这两个政权之间的转变发生在0.01S量级的时间尺度上，因此在缓慢的玻璃政权中设定了细胞事件，如传播、爬行、收缩和入侵。
Material moduli of the cytoskeleton (CSK) influence a wide range of cell functions(1-3). There is substantial evidence from reconstituted F-actin gels that a regime exists in which the moduli scale with frequency with a universal exponent of 3/4. Such behaviour is entropic in origin and is attributable to fluctuations in semi flexible polymers driven by thermal forces(4-7), but it is not obvious a priori that such entropic effects are responsible for the elasticity of the CSK. Here we demonstrate the existence of such a regime in the living cell, but only at high frequencies. Fast events scaled with frequency in a manner comparable to semi flexible-polymer dynamics, but slow events scaled with a non-universal exponent that was systematically smaller than 3/4 and probably more consistent with a soft-glass regime(8,9). These findings strongly suggest that at smaller timescales elasticity arises from entropic fluctuations of a semi flexible-filament network, whereas on longer timescales slow (soft-glass-like) dynamics of a different origin prevail. The transition between these two regimes occurred on timescales of the order of 0.01 s, thus setting within the slow glassy regime cellular events such as spreading, crawling, contracting, and invading.