Local pulsatile contractions are an intrinsic property of the myosin 2A motor in the cortical cytoskeleton of adherent cells.
Local pulsatile contractions are an intrinsic property of the myosin 2A motor in the cortical cytoskeleton of adherent cells.
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DOI：
10.1091/mbc.e16-05-0335
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发表时间：
2017-01-15
影响因子：
3.3
通讯作者：
Waterman CM
中科院分区：
文献类型：
--
作者：
Baird MA;Billington N;Wang A;Adelstein RS;Sellers JR;Fischer RS;Waterman CM
肌球蛋白2A的脉动动力学发生在单个细胞中，是肌球蛋白2A所特有的，肌球蛋白2B没有这种特性，它是肌球蛋白 - 2A马达动力学的结果，而肌球蛋白 - 2B马达不足以诱导这种动态行为。这种脉动收缩是贴壁细胞中肌球蛋白 - 2A/F - 肌动蛋白网络的固有特性。
非肌肉肌球蛋白2（NM2）的脉动动力学在产生发育形态发生所需的收缩力方面的作用已被阐明，但这些脉动收缩是否是所有肌动球蛋白网络的固有特性尚不清楚。在这里，我们利用活细胞荧光成像表明，NM2A“脉冲”的瞬时、局部组装发生在间充质、上皮和肉瘤来源的单个贴壁细胞的皮质细胞骨架中，与发育信号线索以及细胞 - 细胞或细胞 - 细胞外基质相互作用无关。我们表明皮质细胞骨架中的脉冲需要Rho相关激酶或肌球蛋白轻链激酶（MLCK）活性、胞质钙增加以及NM2 ATP酶活性。令人惊讶的是，我们发现皮质细胞骨架脉冲特别需要NM2A的头部结构域，因为无论是NM2B还是2B头部 - 2A尾部嵌合体都不会产生这种脉冲。因此，我们的结果表明皮质细胞骨架中的脉动收缩是NM2A马达的一种固有特性，它可能介导其在贴壁细胞皮质细胞骨架张力稳态维持中的作用。
Pulsatile dynamics of myosin 2A occurs in single cells, is unique to myosin 2A and not 2B, and is a result of the kinetics of the myosin-2A motor, whereas the myosin-2B motor is insufficient to induce this dynamic behavior. This pulsatile contraction is an inherent property of myosin-2A/F-actin networks in adherent cells. The role of nonmuscle myosin 2 (NM2) pulsatile dynamics in generating contractile forces required for developmental morphogenesis has been characterized, but whether these pulsatile contractions are an intrinsic property of all actomyosin networks is not known. Here we used live-cell fluorescence imaging to show that transient, local assembly of NM2A “pulses” occurs in the cortical cytoskeleton of single adherent cells of mesenchymal, epithelial, and sarcoma origin, independent of developmental signaling cues and cell–cell or cell–ECM interactions. We show that pulses in the cortical cytoskeleton require Rho-associated kinase– or myosin light chain kinase (MLCK) activity, increases in cytosolic calcium, and NM2 ATPase activity. Surprisingly, we find that cortical cytoskeleton pulses specifically require the head domain of NM2A, as they do not occur with either NM2B or a 2B-head-2A-tail chimera. Our results thus suggest that pulsatile contractions in the cortical cytoskeleton are an intrinsic property of the NM2A motor that may mediate its role in homeostatic maintenance of tension in the cortical cytoskeleton of adherent cells.