Long astral microtubules uncouple mitotic spindles from the cytokinetic furrow
Long astral microtubules uncouple mitotic spindles from the cytokinetic furrow
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DOI：
10.1083/jcb.201004017
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发表时间：
2010-07-12
影响因子：
7.8
通讯作者：
Wordeman, Linda
中科院分区：
文献类型：
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作者：
Rankin, Kathleen E.;Wordeman, Linda
星状微管（MT）是已知的卵裂沟诱导和纺锤体定位的重要，和星状MT的损失已被报道增加皮层收缩。为了研究过量星形MT活性的影响，我们耗尽了MT解聚剂有丝分裂着丝粒相关驱动蛋白（MCAK）从HeLa细胞产生超长，星形MT在有丝分裂过程中。MCAK耗竭促进后期早期纺锤体剧烈摇摆，其中整个有丝分裂纺锤体在皮质非肌肉肌球蛋白II的振荡驱动下沿纺锤体轴从一个原始子细胞到另一个原始子细胞沿着振荡。紫杉醇治疗的效果是表型模仿。实时成像显示，在分裂后期，皮层肌动蛋白部分空出了极皮层，有利于赤道皮层。我们认为，这使得极性肌动蛋白皮质在正常的收缩活动中容易破裂，长的星形MT扩大了水泡。异常大的泡通过胞质流动取代有丝分裂纺锤体的位置，当泡消退时触发振荡。
Astral microtubules (MTs) are known to be important for cleavage furrow induction and spindle positioning, and loss of astral MTs has been reported to increase cortical contractility. To investigate the effect of excess astral MT activity, we depleted the MT depolymerizer mitotic centromere-associated kinesin (MCAK) from HeLa cells to produce ultra-long, astral MTs during mitosis. MCAK depletion promoted dramatic spindle rocking in early anaphase, wherein the entire mitotic spindle oscillated along the spindle axis from one proto-daughter cell to the other, driven by oscillations of cortical nonmuscle myosin II. The effect was phenocopied by taxol treatment. Live imaging revealed that cortical actin partially vacates the polar cortex in favor of the equatorial cortex during anaphase. We propose that this renders the polar actin cortex vulnerable to rupture during normal contractile activity and that long astral MTs enlarge the blebs. Excessively large blebs displace mitotic spindle position by cytoplasmic flow, triggering the oscillations as the blebs resolve.