Micro- and macrorheological properties of isotropically cross-linked actin networks
Micro- and macrorheological properties of isotropically cross-linked actin networks
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DOI：
10.1529/biophysj.107.112417
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发表时间：
2008-01-15
影响因子：
3.4
通讯作者：
Bausch, Andreas R.
中科院分区：
文献类型：
--
作者：
Luan, Yuxia;Lieleg, Oliver;Bausch, Andreas R.
细胞利用半柔性生物聚合物，例如肌动蛋白或中间体。通过动态调整交联分子的浓度和类型来控制其局部粘弹性响应。所得网络的微观结构主要决定其机械性能。将结构转变与交联分子的分子特性和网络的机械响应联系起来仍然是一个重要的挑战。通过明确的体外模型系统结合显微技术可以最好地实现这一点。在这里，我们表明，随着交联剂重部分肌球蛋白浓度的增加，机械网络响应发生转变。在低交联剂密度下，网络弹性由聚合物的缠结长度 I-e 决定，而在高重 Meromyosin 密度下，交联剂距离 I-c 决定弹性行为。利用微流变学，在低交联剂浓度下观察到异质网络的形成。微观流变学和宏观流变学都报告了向均匀交联相的相同转变。该转变由大约 15 μ m 的恒定平均交联距离 I-c 设定。因此，各向同性交联的体外肌动蛋白网络的微观和宏观力学特性仅由一个内在网络参数决定。
Cells make use of semi flexible biopolymers such as actin or intermediate. laments to control their local viscoelastic response by dynamically adjusting the concentration and type of cross-linking molecules. The microstructure of the resulting networks mainly determines their mechanical properties. It remains an important challenge to relate structural transitions to both the molecular properties of the cross-linking molecules and the mechanical response of the network. This can be achieved best by well defined in vitro model systems in combination with microscopic techniques. Here, we show that with increasing concentrations of the cross-linker heavy meromyosin, a transition in the mechanical network response occurs. At low cross-linker densities the network elasticity is dominated by the entanglement length I-e of the polymer, whereas at high heavy meromyosin densities the cross-linker distance I-c determines the elastic behavior. Using microrheology the formation of heterogeneous networks is observed at low cross-linker concentrations. Micro- and macrorheology both report the same transition to a homogeneous crosslinked phase. This transition is set by a constant average cross-linker distance I-c approximate to 15 mu m. Thus, the micro- and macromechanical properties of isotropically cross-linked in vitro actin networks are determined by only one intrinsic network parameter.