Ran-GTP stabilises microtubule asters and inhibits nuclear assembly in Xenopus egg extracts.
Ran-GTP stabilises microtubule asters and inhibits nuclear assembly in Xenopus egg extracts.
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Ran-GTP 可稳定微管紫苑并抑制非洲爪蟾卵提取物中的核组装。
DOI：
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发表时间：
1999
影响因子：
4
通讯作者：
Paul R. Clarke
中科院分区：
文献类型：
--
作者：
Chuanmao Zhang;Mike F. Hughes;Paul R. Clarke
Ran是Ras超家族的一个丰富的GT酶，在真核生物中高度保守。在间期细胞中，Ran主要在细胞核中，被认为主要是GTP结合的，但它也存在于细胞质中，可能是GDP结合的。这种不对称分布在指导核质转运中起着重要作用。Ran还参与细胞周期控制，包括当细胞核区室化建立时从有丝分裂到间期的转变。在这里，我们已经研究了RAN在这一转变中的作用，使用无细胞系统的非洲爪蟾卵提取物补充精子头部，提供了一个模型微管紫菀形成和后M期核组装。Ran-GTP，作为野生型蛋白添加，GTdR活性缺陷突变体（Q69 L），或通过添加特异性核苷酸交换因子RCC 1产生，稳定在精子中心体处成核的大微管星状体，防止NuMA从星状体重新分布到细胞核，并阻断染色质去浓缩。相反，Ran GDP不稳定微管或抑制核组装。RanT 24 N和RanBP 1，反对由RCC 1产生Ran-GTP，在星形细胞消失后阻止核生长。RAN与卵提取物中的微管星状体和爪蟾体细胞中的有丝分裂纺锤体有关，这表明它可能直接影响微管的稳定性。这些结果表明，Ran在控制微管稳定性方面具有明显不同于核质转运的新功能。Ran GDP/GTP开关可能在协调微管结构变化和与有丝分裂过渡到间期相关的细胞核组装中发挥作用。
Ran is an abundant GTPase of the Ras superfamily that is highly conserved in eukaryotes. In interphase cells, Ran is mainly nuclear and thought to be predominantly GTP-bound, but it is also present in the cytoplasm, probably GDP-bound. This asymmetric distribution plays an important role in directing nucleocytoplasmic transport. Ran has also been implicated in cell cycle control, including the transition from mitosis to interphase when the compartmentalisation of the nucleus is established. Here, we have examined the role of Ran in this transition using a cell-free system of Xenopus egg extracts supplemented with sperm heads that provides a model for microtubule aster formation and post-M phase nuclear assembly. Ran-GTP, added as wild-type protein, a mutant defective in GTPase activity (Q69L), or generated by addition of the specific nucleotide exchange factor RCC1, stabilises large microtubule asters nucleated at the sperm centrosome, prevents the redistribution of NuMA from the aster to the nucleus and blocks chromatin decondensation. In contrast, Ran GDP does not stabilise microtubules or inhibit nuclear assembly. RanT24N and RanBP1, which oppose the generation of Ran-GTP by RCC1, arrest nuclear growth after disappearance of the aster. Ran associates with microtubule asters in egg extracts and with mitotic spindles in somatic Xenopus cells, suggesting that it may affect microtubule stability directly. These results show that Ran has a novel function in the control of microtubule stability that is clearly distinct from nucleocytoplasmic transport. The Ran GDP/GTP switch may play a role in co-ordinating changes in the structure of microtubules and the assembly of the nucleus associated with the transition from mitosis to interphase.
DOI：
10.1073/pnas.92.5.1436
发表时间：
1995-02-28
影响因子：
11.1
作者：
DEMETER, J;MORPHEW, M;SAZER, S
通讯作者：
SAZER, S