Dynamics of actin filaments during tension-dependent formation of actin bundles
Dynamics of actin filaments during tension-dependent formation of actin bundles
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DOI：
10.1016/j.bbagen.2007.03.010
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发表时间：
2007-08-01
影响因子：
3
通讯作者：
Sokabe, Masahiro
中科院分区：
文献类型：
--
作者：
Hirata, Hiroaki;Tatsumi, Hitoshi;Sokabe, Masahiro
肌动蛋白细胞骨架应力纤维是一种基于肌动球蛋白的收缩结构，被视为一束肌动蛋白丝。尽管细胞中的张力发展被认为调节应力纤维的形成，但对潜在的生物物理机制知之甚少。为了解决这个问题，我们研究了张力对单个肌动蛋白丝的行为的影响，在应力纤维（肌动蛋白束）形成过程中，使用无细胞溶质的半完整成纤维细胞，用Rho激酶抑制剂Y-27632预处理，将应力纤维拆解成肌动蛋白丝的网状结构。这些细丝稀疏地用量子点标记，以实时跟踪它们的运动。当ATP和Ca 2+被施加到半完整的细胞产生肌动球蛋白为基础的力量，肌动蛋白网络在突出的椎板被拖向细胞体，而网络的周边仍然在原来的区域，表明向心定向张力在网络开发。然后，在网络中的单个肌动蛋白丝向细胞体移动，并伴随着它们的运动方向的突然变化，最终形成沿着张力方向的肌动蛋白束。通过外部施加的机械力拖动网状物也产生基本相同的效果。这些结果表明，存在的张力依赖性重塑的交联网内的肌动蛋白丝的重排过程中，从而表明，张力是一个关键的球员，以调节动态的个别肌动蛋白丝，导致肌动蛋白束的形成。(C)2007 Elsevier B. V.保留所有权利。
The actin cytoskeleton stress fiber is an actomyosin-based contractile structure seen as a bundle of actin filaments. Although tension development in a cell is believed to regulate stress fiber fort-nation, little is known for the underlying biophysical mechanisms. To address this question, we examined the effects of tension on the behaviors of individual actin filaments during stress fiber (actin bundle) formation using cytosol-free semi-intact fibroblast cells that were pre-treated with the Rho kinase inhibitor Y-27632 to disassemble stress fibers into a meshwork of actin filaments. These filaments were sparsely labeled with quantum dots for live tracking of their motions. When ATP and Ca2+ were applied to the semi-intact cells to generate actomyosin-based forces, actin meshwork in the protruded lamellae was dragged toward the cell body, while the periphery of the meshwork remained in the original region, indicating that centripetally directed tension developed in the meshwork. Then the individual actin filaments in the meshwork moved towards the cell body accompanied with sudden changes in the direction of their movements, finally forming actin bundles along the direction of tension. Dragging the meshwork by externally applied mechanical forces also exerted essentially the same effects. These results suggest the existence of tension-dependent remodeling of cross-links within the meshwork during the rearrangement of actin filaments, thus demonstrating that tension is a key player to regulate the dynamics of individual actin filaments that leads to actin bundle formation. (C) 2007 Elsevier B.V. All rights reserved.