The Nup107-160 nucleoporin complex is required for correct bipolar spindle assembly
The Nup107-160 nucleoporin complex is required for correct bipolar spindle assembly
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DOI：
10.1091/mbc.e05-11-1061
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发表时间：
2006-09-01
影响因子：
3.3
通讯作者：
Forbes, Douglass J.
中科院分区：
文献类型：
--
作者：
Orjalo, Arturo V.;Arnaoutov, Alexei;Forbes, Douglass J.
Nup107-160复合体是核孔的关键亚基。该复合体定位于哺乳动物有丝分裂细胞中的着丝点，其功能尚不清楚。为了检测Nup107-160复合体对着丝点的招募，我们用抗血清对人细胞进行了四种复合体成分的染色。每种抗体不仅可以染色着丝点，还可以染色纺锤体前中期的纺锤体极点和近端纺锤体纤维，这反映了纺锤体检查点蛋白Mad1、Mad2、Bub3和Cdc20在前中期的双重定位。事实上，Nup107-160复合体的扩展月形包围了未附着的着丝点，类似于观察到的动态外部着丝点检查点蛋白和未附着着丝点上的马达的超积累。在有丝分裂的爪蟾卵提取物中，Nup107-160复合物定位于整个重建的纺锤体。当Nup107-160复合物从提取物中去除时，纺锤体检查点保持完整，但纺锤体组装出现明显缺陷。精子中心体周围的微管成核似乎正常，但微管很快解体，留下大部分未附着的精子染色质。值得注意的是，Ran- gtp在枯竭提取物中引起了微管紫菀的正常组装，这表明这种缺陷位于Ran的上游或独立于Ran。我们得出结论，Nup107-160复合体在有丝分裂中是动态的，它促进纺锤体组装的方式不同于它在间期核孔中的功能。
The Nup107-160 complex is a critical subunit of the nuclear pore. This complex localizes to kinetochores in mitotic mammalian cells, where its function is unknown. To examine Nup107-160 complex recruitment to kinetochores, we stained human cells with antisera to four complex components. Each antibody stained not only kinetochores but also prometaphase spindle poles and proximal spindle fibers, mirroring the dual prometaphase localization of the spindle checkpoint proteins Mad1, Mad2, Bub3, and Cdc20. Indeed, expanded crescents of the Nup107-160 complex encircled unattached kinetochores, similar to the hyperaccumulation observed of dynamic outer kinetochore checkpoint proteins and motors at unattached kinetochores. In mitotic Xenopus egg extracts, the Nup107-160 complex localized throughout reconstituted spindles. When the Nup107-160 complex was depleted from extracts, the spindle checkpoint remained intact, but spindle assembly was rendered strikingly defective. Microtubule nucleation around sperm centrosomes seemed normal, but the microtubules quickly disassembled, leaving largely unattached sperm chromatin. Notably, Ran-GTP caused normal assembly of microtubule asters in depleted extracts, indicating that this defect was upstream of Ran or independent of it. We conclude that the Nup107-160 complex is dynamic in mitosis and that it promotes spindle assembly in a manner that is distinct from its functions at interphase nuclear pores.