Phosphorylation of Crm1 by CDK1-cyclin-B promotes Ran-dependent mitotic spindle assembly
Phosphorylation of Crm1 by CDK1-cyclin-B promotes Ran-dependent mitotic spindle assembly
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CDK1-cyclin-B 磷酸化 Crm1 可促进 Ran 依赖性有丝分裂纺锤体组装。
DOI：
10.1242/jcs.126854
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发表时间：
2013-08-01
影响因子：
4
通讯作者：
Zhang, Chuanmao
中科院分区：
文献类型：
--
作者：
Wu, Zhige;Jiang, Qing;Zhang, Chuanmao
动物细胞中的有丝分裂纺锤体组装是由指导微管稳定的染色体依赖性途径精心策划的。染色体上产生的 RanGTP 从与导入蛋白的抑制复合物中释放纺锤体组装因子，导入蛋白是促进蛋白质在间期导入细胞核的核转运因子。此外，核输出因子 Crm1 被认为通过在有丝分裂纺锤体上，特别是在中心体和着丝粒上局部组装蛋白质复合物，充当 RanGTP 的有丝分裂效应子。然而，目前尚不清楚核转运因子的功能在有丝分裂过程中是如何控制的。在此，我们报道人类 Crm1 在有丝分裂中的丝氨酸 391 处被 CDK1-细胞周期蛋白-B（即 CDK1 和细胞周期蛋白 B 复合物）磷酸化。丝氨酸 391 突变为非磷酸化或磷酸化模拟残基的 Crm1 表达表明，磷酸化将 Crm1 定位到有丝分裂纺锤体，并促进纺锤体组装、微管稳定和染色体排列。我们发现 Crm1 在丝氨酸 391 处的磷酸化增强了其与 RanGAP1-RanBP2 的 RanGTP 依赖性相互作用，并促进它们招募到有丝分裂纺锤体。这些结果表明，Crm1 的磷酸化控制其在有丝分裂过程中的分子相互作用、定位和功能，揭示了 CDK1-cyclin-B 控制有丝分裂纺锤体组装的新机制。我们提出，通过蛋白质磷酸化选择特定的分子相互作用，在有丝分裂过程中控制核转运因子。
Mitotic spindle assembly in animal cells is orchestrated by a chromosome-dependent pathway that directs microtubule stabilization. RanGTP generated at chromosomes releases spindle assembly factors from inhibitory complexes with importins, the nuclear transport factors that facilitate protein import into the nucleus during interphase. In addition, the nuclear export factor Crm1 has been proposed to act as a mitotic effector of RanGTP through the localized assembly of protein complexes on the mitotic spindle, notably at centrosomes and kinetochores. It has been unclear, however, how the functions of nuclear transport factors are controlled during mitosis. Here, we report that human Crm1 is phosphorylated at serine 391 in mitosis by CDK1-cyclin-B (i.e. the CDK1 and cyclin B complex). Expression of Crm1 with serine 391 mutated to either non-phosphorylated or phosphorylation-mimicking residues indicates that phosphorylation directs the localization of Crm1 to the mitotic spindle and facilitates spindle assembly, microtubule stabilization and chromosome alignment. We find that phosphorylation of Crm1 at serine 391 enhances its RanGTP-dependent interaction with RanGAP1-RanBP2 and promotes their recruitment to the mitotic spindle. These results show that phosphorylation of Crm1 controls its molecular interactions, localization and function during mitosis, uncovering a new mechanism for the control of mitotic spindle assembly by CDK1-cyclin-B. We propose that nuclear transport factors are controlled during mitosis through the selection of specific molecular interactions by protein phosphorylation.