Dynactin-dependent cortical dynein and spherical spindle shape correlate temporally with meiotic spindle rotation in Caenorhabditis elegans.
Dynactin-dependent cortical dynein and spherical spindle shape correlate temporally with meiotic spindle rotation in Caenorhabditis elegans.
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DOI：
10.1091/mbc.e15-05-0290
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发表时间：
2015-09-01
影响因子：
3.3
通讯作者：
McNally FJ
中科院分区：
文献类型：
--
作者：
Crowder ME;Flynn JR;McNally KP;Cortes DB;Price KL;Kuehnert PA;Panzica MT;Andaya A;Leary JA;McNally FJ
细胞质动力蛋白在秀丽隐杆线虫雌性减数分裂纺锤体旋转前的皮层上积累。这些纺锤体也会缩短成球形，这可能会减少动力蛋白对皮质的拉力。卵母细胞减数分裂纺锤体的方向是一极与皮质并列，以促进染色体进入极体。在秀丽隐杆线虫中，这些无中心纺锤体最初平行于皮层定向，然后旋转到垂直方向。为了理解纺锤体旋转的机制，我们描述了与旋转时间相关的事件，包括极-极轴中纺锤体的缩短，这导致了旋转时的近球形纺锤体。通过对多倍体C.线虫和相关的线虫物种，我们发现纺锤体旋转开始在一个定义的球形形状，而不是在一个定义的纺锤体长度。此外，在旋转前，动力蛋白在皮质上积累，微管从纺锤体中生长，在旋转过程中，微管的正端向外。动力蛋白耗竭阻止了动力蛋白在皮质上的积累，并阻止了纺锤体旋转，而与纺锤体形状无关。这些结果支持皮质牵拉模型，其中纺锤体形状可能有助于旋转，因为球体可以旋转而不使相邻的弹性细胞质变形。我们还提出的证据表明，纺锤体旋转的激活是由p150 dynactin的基本结构域的去磷酸化促进的。
Cytoplasmic dynein accumulates on the cortex of Caenorhabditis elegans female meiotic spindles just before they rotate in a dynein-dependent manner. These spindles also shorten to a spherical shape that might reduce the drag that opposes cortical pulling by dynein. Oocyte meiotic spindles orient with one pole juxtaposed to the cortex to facilitate extrusion of chromosomes into polar bodies. In Caenorhabditis elegans, these acentriolar spindles initially orient parallel to the cortex and then rotate to the perpendicular orientation. To understand the mechanism of spindle rotation, we characterized events that correlated temporally with rotation, including shortening of the spindle in the pole-to pole axis, which resulted in a nearly spherical spindle at rotation. By analyzing large spindles of polyploid C. elegans and a related nematode species, we found that spindle rotation initiated at a defined spherical shape rather than at a defined spindle length. In addition, dynein accumulated on the cortex just before rotation, and microtubules grew from the spindle with plus ends outward during rotation. Dynactin depletion prevented accumulation of dynein on the cortex and prevented spindle rotation independently of effects on spindle shape. These results support a cortical pulling model in which spindle shape might facilitate rotation because a sphere can rotate without deforming the adjacent elastic cytoplasm. We also present evidence that activation of spindle rotation is promoted by dephosphorylation of the basic domain of p150 dynactin.