Aurora B phosphorylates centromeric MCAK and regulates its localization and microtubule depolymerization activity
Aurora B phosphorylates centromeric MCAK and regulates its localization and microtubule depolymerization activity
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DOI：
10.1016/j.cub.2004.01.055
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发表时间：
2004-02-17
期刊：
影响因子：
9.2
通讯作者：
Stukenberg, PT
中科院分区：
文献类型：
--
作者：
Lan, WJ;Zhang, X;Stukenberg, PT
背景：在有丝分裂过程中，姐妹动粒必须以双极方式结合微管以均等地分离染色体。这一过程的分子机制尚不清楚。Aurora B可能通过调节着丝粒-微管附着促进染色体双定向。有丝分裂着丝粒相关驱动蛋白（mitotic centromere-associated kinesin，MCAK）是一种能使微管解聚的Kin 1驱动蛋白。这两种蛋白质都定位于有丝分裂的着丝粒，并有重叠的有丝分裂功能，包括微管动力学的调节，正确的染色体congression，和纠正不当的kinetochore-microtubule attachments.Results：我们发现，极光B磷酸化和调节MCAK在体外和体内。具体来说，我们映射六极光B磷酸化位点MCAK在着丝粒靶向域和颈部区域。极光B活动所需的本地化MCAK的着丝粒，但不是纺锤体极。MCAK颈部丝氨酸196的Aurora B磷酸化抑制其微管解聚活性。我们发现这个关键位点在体内的着丝粒和后期纺锤体中间区被磷酸化。然而，在内部的着丝粒有口袋的磷酸化和未磷酸化的MCAK蛋白，这表明磷酸周转是至关重要的MCAK活性的调节。此外，α-P-S196抗体爪蟾卵提取物或注射α-P-S196抗体到细胞中引起的染色体定位和/或segregation.Conclusions缺陷：我们已经建立了微管解聚酶MCAK和极光B激酶之间的直接联系。我们的数据表明，极光B的积极和消极调节MCAK在有丝分裂。我们建议，极光B biorients染色体通过指导MCAK determining不正确取向的动粒微管。
Background: Sister kinetochores must bind microtubules in a bipolar fashion to equally segregate chromosomes during mitosis. The molecular mechanisms underlying this process remain unclear. Aurora B likely promotes chromosome biorientation by regulating kinetochore-microtubule attachments. MCAK (mitotic centromere-associated kinesin) is a Kin 1 kinesin that can depolymerize microtubules. These two proteins both localize to mitotic centromeres and have overlapping mitotic functions, including regulation of microtubule dynamics, proper chromosome congression, and correction of improper kinetochore-microtubule attachments.Results: We show that Aurora B phosphorylates and regulates MCAK both in vitro and in vivo. Specifically, we mapped six Aurora B phosphorylation sites on MCAK in both the centromere-targeting domain and the neck region. Aurora B activity was required to localize MCAK to centromeres, but not to spindle poles. Aurora B phosphorylation of serine 196 in the neck region of MCAK inhibited its microtubule depolymerization activity. We found that this key site was phosphorylated at centromeres and anaphase spindle midzones in vivo. However within the inner centromere there were pockets of both phosphorylated and unphosphorylated MCAK protein, suggesting that phosphate turnover is crucial in the regulation of MCAK activity. Addition of alpha-p-S196 antibodies to Xenopus egg extracts or injection of alpha-p-S196 antibodies into cells caused defects in chromosome positioning and/or segregation.Conclusions: We have established a direct link between the microtubule depolymerase MCAK and Aurora B kinase. Our data suggest that Aurora B both positively and negatively regulates MCAK during mitosis. We propose that Aurora B biorients chromosomes by directing MCAK to depolymerize incorrectly oriented kinetochore microtubules.