The role of myosin II motor activity in distributing myosin asymmetrically and coupling protrusive activity to cell translocation
The role of myosin II motor activity in distributing myosin asymmetrically and coupling protrusive activity to cell translocation
复制标题
DOI：
10.1091/mbc.e06-05-0431
复制
发表时间：
2006-10-01
影响因子：
3.3
通讯作者：
Kolega, John
中科院分区：
文献类型：
--
作者：
Kolega, John
非肌肌球蛋白IIA和IIB优先分布于迁移内皮细胞的两端。为了理解这种行为的机制和功能，在用运动抑制剂blebbistatin处理的细胞中检查了肌球蛋白II。当浓度≥ 30 μ M时，Blebbistatin抑制肌球蛋白IIA的前分布，而100 μ M时，Blebbistatin引起肌球蛋白IIA的后积累。肌球蛋白IIB的后部积聚不受影响。延时电影显微摄影显示肌球蛋白IIA进入板状伪足后不久，他们的形成，但未能移动到板状伪足blebbistatin。因此，肌球蛋白II需要运动活动向前移动到突起中的F-肌动蛋白上。然而，这种运动是抑制肌球蛋白丝组装，因为整个肌球蛋白延迟相对于无尾片段。抑制肌球蛋白的向前运动减少了细胞体的伸展活动和移位之间的耦合：在未处理的细胞中，身体运动跟随着推进的板状伪足，而blebbistatin处理的细胞延长了突起，而没有身体的位移或在运动之前有更长的延迟。blebbistatin处理的细胞的前细胞质中含有混乱的平行微丝束，但在未处理的细胞中的前F-肌动蛋白束主要是垂直于运动方向。肌球蛋白II通常可以在肌动蛋白丝上向前移动，并将交叉的肌动蛋白丝拉成反平行的纤维束，从而使细胞体向前排列。
Nonmuscle myosin IIA and IIB distribute preferentially toward opposite ends of migrating endothelial cells. To understand the mechanism and function of this behavior, myosin II was examined in cells treated with the motor inhibitor, blebbistatin. Blebbistatin at >= 30 mu M inhibited anterior redistribution of myosin IIA, with 100 mu M blebbistatin causing posterior accumulation. Posterior accumulation of myosin IIB was unaffected. Time-lapse cinemicrography showed myosin IIA entering lamellipodia shortly after, their formation, but failing to move into lamellipodia in blebbistatin. Thus, myosin II requires motor activity to move forward onto F-actin in protrusions. However, this movement is inhibited by myosin filament assembly, because whole myosin was delayed relative to a tailless fragment. Inhibiting myosin's forward movement reduced coupling between protrusive activity and translocation of the cell body: In untreated cells, body movement followed advancing lamellipodia, whereas blebbistatin-treated cells extended protrusions without displacement of the body or with a longer delay before movement. Anterior cytoplasm of blebbistatin-treated cells contained disorganized bundles of parallel microfilaments, but anterior F-actin bundles in untreated cells were mostly oriented perpendicular to movement. Myosin II may ordinarily move anteriorly on actin filaments and pull crossed filaments into antiparallel bundles, with the resulting realignment pulling the cell body forward.