Spring-like behavior of cytoplasm holds the mitotic spindle in place.
Spring-like behavior of cytoplasm holds the mitotic spindle in place.
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DOI：
10.1073/pnas.2203036119
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发表时间：
2022-04-05
影响因子：
11.1
通讯作者：
中科院分区：
文献类型：
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在细胞生物学教科书中，细胞质通常被描述为均匀的颜色，沐浴在细胞核和细胞器中，给人留下的印象是它由没有结构或物理特性的液体溶液组成。事实上，细胞质挤满了大分子 (1) 并由细胞骨架网络 (2) 组织，赋予其粘性和弹性特性 (2)，但这些特性的生物学意义往往不清楚。在《美国国家科学院院刊》中，Xie 等人 (3) 使用磁力镊子置换海胆胚胎中的有丝分裂纺锤体，发现移位后纺锤体会弹回来。值得注意的是，维持纺锤体位置的弹性并不依赖于微管，而仅部分依赖于肌动蛋白，这表明细胞质的拥挤性质可能有所贡献。在细胞分裂过程中，真核细胞组装有丝分裂纺锤体，其位置决定分裂几何形状，有时还决定子细胞的发育命运 (4)。在对称分裂中，纺锤体位于细胞的中心。它如何实现这个中心位置已经在多种生物体中进行了研究。在大多数后生动物中，纺锤体的两极由称为紫苑的径向微管阵列定义。微管在 aster 中心成核，其生长受到动态不稳定性的限制，导致最大有丝分裂 aster 半径约为 30 μm (5)。如果细胞半径小于此值，则纺锤体在整个有丝分裂过程中通过接触皮质的微管动态定位，如秀丽隐杆线虫胚胎 (6)。如果更长，如非洲爪蟾胚胎中那样，纺锤体在前一个间期中由微管限定的中心位置形成 (7, 8)。在如此大的细胞中，纺锤体必须在整个有丝分裂过程中保持在适当的位置，而不与皮质相连，而保持其存在的机制尚不清楚。 Xie等人(3)分析的海胆胚胎半径约为48μm，有丝分裂半径约为25μm，因此它们处于大细胞状态，并提供了一个系统来探测维持纺锤体位置的机制。
In cell biology textbooks, cytoplasm is often depicted as a homogeneous color that bathes the nucleus and organelles, leaving the impression that it consists of a liquid solution without structure or physical properties. In reality, cytoplasm is crowded with macromolecules (1) and organized by cytoskeletal networks (2), which endow it with both viscous and elastic properties (2), but the biological significance of these properties is often unclear. In PNAS, Xie et al.(3) use magnetic tweezers to displace the mitotic spindle in sea urchin embryos and find that it springs back when displaced. Remarkably, the elasticity that maintains spindle position does not depend on microtubules and only partly depends on actin, suggesting that the crowded nature of cytoplasm may contribute. During cell division, eukaryotic cells assemble a mitotic spindle whose position determines cleavage geometry and sometimes, the developmental fate of daughter cells (4). In symmetric divisions, the spindle is positioned at the center of the cell. How it achieves this central location has been studied in multiple organisms. In most metazoans, the poles of the spindle are defined by radial arrays of microtubules called asters. Microtubules are nucleated at the aster center, and their growth is bounded by dynamic instability, leading to a maximum mitotic aster radius of∼ 30 μm (5). If the cell radius is shorter than this, the spindle is positioned dynamically throughout mitosis by microtubules that touch the cortex, as in Caenorhabditis elegans embryos (6). If longer, as in Xenopus embryos, the spindle forms at a central location defined by microtubules in the preceding interphase (7, 8). In such large cells, the spindle has to remain in position throughout mitosis without connections to the cortex, and the mechanisms that keep it there have been unclear. The sea urchin embryos analyzed by Xie et al.(3) have a radius of∼ 48 μm and a mitotic aster radius of∼ 25 μm, so they are in the large cell regime and provide a system to probe the mechanisms used to maintain spindle location.
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影响因子：
2.9
作者：
Mitchison, Timothy;Wuehr, Martin;Phuong Nguyen;Ishihara, Keisuke;Groen, Aaron;Field, Christine M.
通讯作者：
Field, Christine M.
DOI：
10.1073/pnas.2115593119
发表时间：
2022-02-22
影响因子：
11.1
作者：
Xie J;Najafi J;Le Borgne R;Verbavatz JM;Durieu C;Sallé J;Minc N
通讯作者：
Minc N
影响因子：
56.9
作者：
Grill, SW;Howard, J;Hyman, A
通讯作者：
Hyman, A
影响因子：
3.7
作者：
CRICK, FHC;HUGHES, AFW
通讯作者：
HUGHES, AFW
DOI：
10.1073/pnas.0901462106
发表时间：
2009-06-30
影响因子：
11.1
作者：
Zhou, E. H.;Trepat, X.;Fredberg, J. J.
通讯作者：
Fredberg, J. J.