有丝分裂纺锤体组装需要含Rae1的核糖核蛋白复合物。

A Rae1-containing ribonucleoprotein complex is required for mitotic spindle assembly.

作者信息

Blower Michael D, Nachury Maxence, Heald Rebecca, Weis Karsten

机构信息

Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720, USA.

出版信息

Cell. 2005 Apr 22;121(2):223-34. doi: 10.1016/j.cell.2005.02.016.

DOI:10.1016/j.cell.2005.02.016

PMID:15851029

Abstract

Centrosome-independent microtubule polymerization around chromosomes has been shown to require a local gradient of RanGTP, which discharges mitotic cargoes from the nuclear import receptor importin beta. Here, we have used an activity-based assay in Xenopus egg extracts to purify the mRNA export protein Rae1 as a spindle assembly factor regulated by this pathway. Rae1 is a microtubule-associated protein that binds directly to importin beta. Depletion of Rae1 from extracts or cells severely inhibits mitotic spindle assembly. A purified Rae1 complex stabilizes microtubules in egg extracts in a RanGTP/importin beta-regulated manner. Interestingly, Rae1 exists in a large ribonucleoprotein complex, which requires RNA for its activity to control microtubule dynamics in vitro. Furthermore, we provide evidence that RNA associates with the mitotic spindle and that it plays a direct, translation-independent role in spindle assembly. Our studies reveal an unexpected function for RNA in spindle morphogenesis.

摘要

已证明，染色体周围不依赖中心体的微管聚合需要RanGTP的局部梯度，该梯度可从核输入受体输入蛋白β释放有丝分裂货物。在这里，我们使用基于活性的分析方法在非洲爪蟾卵提取物中纯化了mRNA输出蛋白Rae1，作为受该途径调节的纺锤体组装因子。Rae1是一种与微管相关的蛋白，可直接与输入蛋白β结合。从提取物或细胞中耗尽Rae1会严重抑制有丝分裂纺锤体组装。纯化的Rae1复合物以RanGTP/输入蛋白β调节的方式稳定卵提取物中的微管。有趣的是，Rae1存在于一个大型核糖核蛋白复合物中，该复合物在体外控制微管动力学的活性需要RNA。此外，我们提供的证据表明RNA与有丝分裂纺锤体相关，并且它在纺锤体组装中发挥直接的、不依赖翻译的作用。我们的研究揭示了RNA在纺锤体形态发生中的意外功能。