Patronin mediates a switch from kinesin-13-dependent poleward flux to anaphase B spindle elongation.
Patronin mediates a switch from kinesin-13-dependent poleward flux to anaphase B spindle elongation.
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Patronin 介导从驱动蛋白 13 依赖性极向通量到后期 B 纺锤体伸长的转变。
DOI：
10.1083/jcb.201306001
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Scholey,JonathanM
中科院分区：
文献类型：
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作者：
Wang,Haifeng;Brust-Mascher,Ingrid;Civelekoglu-Scholey,Gul;Scholey,JonathanM
有丝分裂期间的染色体分离涉及染色体至极运动性（后期A）和纺锤体伸长（后期B; Ris，1943; Goshima和Scholey，2010; Walczak等人，2010; Drechsler和McAinsh，2012; McIntosh等人，2012年）。在Dro sophila melanogaster胚胎中，而后期A取决于组合的pacman-flux机制（Rogers等人，2004），我们提出后期B依赖于持续的驱动蛋白-5产生的极间微管（MT; ipMT）滑动丝机制，当向极通量关闭时，该机制“接合”以推开纺锤体极（科尔等人，1994; Kashina等人，1996; Brust-Mascher和Scholey，2002; Brust-Mascher等人，2004，2009; Cheerambathur等人，2007;货车den Wildenberg等人，2008; de Lartigue等人，2011; Acar等人，2013年）。因此，在前期后期B纺锤体中，ipMT的向外滑动通过其负端在两极的解聚来平衡，产生向极的通量，并且纺锤体保持稳定的长度（“进料器-削片器机制”; Gadde和Heald，2004）。然而，在细胞周期蛋白B降解后，ipMT负端解聚停止，因此向极流动被关闭，向外滑动的ipMT现在可以延长纺锤体。与此同时，ipMT plus端显示出净增长，并招募MT-MT交联剂，以组装一个更强大的中间区，滑动马达在其中起作用。在这里，我们通过研究驱动蛋白-13 KLP 10 A的作用来测试我们的假设，即解聚ipMT负末端在两极周围的特异性稳定化触发了后期B的开始（Rogers等人，2004）和其拮抗剂Patronin，其特异性地起作用以稳定MT负末端对抗驱动蛋白-13催化的解聚（Goodwin和Vale，2010）。Patronin和KLP 10A的抑制产生短中期（Goshima et al.，2007）和塌陷或持续伸长的前中期纺锤体（Rogers et al.，2004），但它们在后期B（纺锤体的生化和机械状态与这些早期有丝分裂阶段不同时）中的作用尚不清楚。我们发现，（a）Patronin抵消KLP 10 A在纺锤体极的活性，关闭向极通量，诱导后期B纺锤体伸长，说明ipMT负端动力学变化的重要作用;和（B）KLP 10 A活性的抑制足以启动不可降解的细胞周期蛋白B停滞的纺锤体的伸长，其速率和程度特征正常的后期B。
Chromosome segregation during mitosis involves chromosome to pole motility (anaphase A) and spindle elongation (anaphase B; Ris, 1943; Goshima and Scholey, 2010; Walczak et al., 2010; Drechsler and McAinsh, 2012; McIntosh et al., 2012). In Dro sophila melanogaster embryos, whereas anaphase A depends on a combined pacman-flux mechanism (Rogers et al., 2004), we propose that anaphase B depends on a persistent kinesin-5–generated interpolar microtubule (MT; ipMT) sliding filament mechanism that “engages” to push apart the spindle poles when poleward flux is turned off (Cole et al., 1994; Kashina et al., 1996; Brust-Mascher and Scholey, 2002; Brust-Mascher et al., 2004, 2009; Cheerambathur et al., 2007; van den Wildenberg et al., 2008; de Lartigue et al., 2011; Acar et al., 2013). Thus, in preanaphase B spindles, the outward sliding of ipMTs is balanced by the depolymerization of their minus ends at the poles, producing poleward flux, and the spindle maintains a steady length (the “feeder–chipper mechanism”; Gadde and Heald, 2004). After cyclin B degradation, however, ipMT minus-end depolymerization ceases, so poleward flux is turned off, and the outwardly sliding ipMTs can now elongate the spindle. At the same time, ipMT plus ends display net growth and recruit MT–MT cross-linkers to assemble a more robust midzone where the sliding motors act. Here, we tested our hypothesis that the specific stabilization of depolymerizing ipMT minus ends around the poles triggers anaphase B onset by investigating the roles of the kinesin-13 KLP10A (Rogers et al., 2004) and its antagonist, Patronin, which functions specifically to stabilize MT minus ends against kinesin-13–catalyzed depolymerization (Goodwin and Vale, 2010). The inhibition of Patronin and KLP10A produces short metaphase (Goshima et al., 2007) and collapsed or persistently elongating prometaphase spindles (Rogers et al., 2004), respectively, but their roles in anaphase B, when the biochemical and mechanical state of the spindle differs from these earlier mitotic phases, are unknown. We show that (a) Patronin counteracts KLP10A activity at spindle poles to turn off poleward flux and induce anaphase B spindle elongation, illustrating an important role for changes in ipMT minus-end dynamics; and (b) the inhibition of KLP10A activity is sufficient to initiate the elongation of nondegradable cyclin B–arrested spindles at a rate and extent characteristic of normal anaphase B.