The ultrastructural organization of actin and myosin II filaments in the contractile ring: new support for an old model of cytokinesis.
The ultrastructural organization of actin and myosin II filaments in the contractile ring: new support for an old model of cytokinesis.
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DOI：
10.1091/mbc.e16-06-0466
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发表时间：
2017-03-01
影响因子：
3.3
通讯作者：
Shuster CB
中科院分区：
文献类型：
--
作者：
Henson JH;Ditzler CE;Germain A;Irwin PM;Vogt ET;Yang S;Wu X;Shuster CB
胞质分裂研究中的一个主要问题是动物细胞收缩环中肌动蛋白和非肌肉肌球蛋白II细丝的精确结构。超分辨和透射电子显微镜支持肌动球蛋白组织与滑丝/荷包串模型的胞质分裂。尽管最近的进展，我们了解的组件和空间调节的收缩环（CR），精确的超微结构的肌动蛋白和肌球蛋白II的动物细胞CR内仍然是一个悬而未决的问题。我们使用超分辨率光学显微镜和铂复制透射电子显微镜（TEM）来确定从分裂的海胆胚胎中制备的分离皮质细胞骨架中肌动蛋白和肌球蛋白II的结构组织。三维结构照明显微镜表明，在CR，肌动蛋白和肌球蛋白II丝组织成紧密堆积的线性阵列，定向沿着轴的收缩和限制在一个狭窄的区域内的沟。相比之下，肌球蛋白II丝在胞质分裂的早期阶段组织成小，离散，并定期间隔的集群。透射电镜显示，肌动蛋白在CR形成了一个密集的和各向异性的阵列的细长，反平行的细丝，而肌球蛋白II组织成横向相关的，头对头的丝链高度联想到哺乳动物细胞应力纤维。总之，这些结果不仅支持典型的“荷包”模型的收缩环收缩，但也表明，CR可能是来自肌球蛋白II丝的焦点，在一种类似的方式已被证明在裂变酵母。
A major question in cytokinesis research is the precise architecture of actin and nonmuscle myosin II filaments in the animal cell contractile ring. Superresolution and transmission electron microscopy support an actomyosin organization consistent with the sliding-filament/purse-string model of cytokinesis. Despite recent advances in our understanding of the components and spatial regulation of the contractile ring (CR), the precise ultrastructure of actin and myosin II within the animal cell CR remains an unanswered question. We used superresolution light microscopy and platinum replica transmission electron microscopy (TEM) to determine the structural organization of actin and myosin II in isolated cortical cytoskeletons prepared from dividing sea urchin embryos. Three-dimensional structured illumination microscopy indicated that within the CR, actin and myosin II filaments were organized into tightly packed linear arrays oriented along the axis of constriction and restricted to a narrow zone within the furrow. In contrast, myosin II filaments in earlier stages of cytokinesis were organized into small, discrete, and regularly spaced clusters. TEM showed that actin within the CR formed a dense and anisotropic array of elongate, antiparallel filaments, whereas myosin II was organized into laterally associated, head-to-head filament chains highly reminiscent of mammalian cell stress fibers. Together these results not only support the canonical “purse-string” model for contractile ring constriction, but also suggest that the CR may be derived from foci of myosin II filaments in a manner similar to what has been demonstrated in fission yeast.