Centrosomes [1, 2] play a central role during spindle assembly in most animal cells [3]. In early mitosis, they organize two symmetrical microtubule arrays that upon separation define the two poles of the forming spindle. Centrosome separation is tightly regulated [4, 5], occurring through partially redundant mechanisms that rely on the action of microtubule-based dynein and kinesin motors and the actomyosin system [6]. While centrosomes can separate in prophase or in prometaphase after nuclear envelope breakdown (NEBD), prophase centrosome separation optimizes spindle assembly and minimizes the occurrence of abnormal chromosome attachments that could end in aneuploidy [7, 8]. Prophase centrosome separation relies on the activity of Eg5/KIF11, a mitotic kinesin [9] that accumulates around centrosomes in early mitosis under the control of CDK1 and the Nek9/Nek6/7 kinase module [10-17]. Here, we show that Eg5 localization and centrosome separation in prophase depend on the nuclear microtubule-associated protein TPX2 [18], a pool of which localizes to the centrosomes before NEBD. This localization involves RHAMM/HMMR [19] and the kinase Nek9 [20], which phosphorylates TPX2 nuclear localization signal (NLS) preventing its interaction with importin and nuclear import. The pool of centrosomal TPX2 in prophase has a critical role for both microtubule aster organization and Eg5 localization, and thereby for centrosome separation. Our results uncover an unsuspected role for TPX2 before NEBD and define a novel regulatory mechanism for centrosome separation in prophase. They furthermore suggest NLS phosphorylation as a novel regulatory mechanism for spindle assembly factors controlled by the importin/Ran system.
Pubmed ID: 29276125 RIS Download
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This unknown targets Mouse IgG (H+L)
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View all literature mentionsThis polyclonal targets Goat Mouse IgG HRP Affinity Purified PAb
View all literature mentionsThis polyclonal targets Rabbit IgG
View all literature mentionsThis polyclonal targets Human Eg5
View all literature mentionsThis polyclonal targets NTF97/Importin beta antibody
View all literature mentionsThis polyclonal targets LMNB1
View all literature mentionsThis polyclonal targets Pericentrin
View all literature mentionsThis monoclonal targets Tubulin, gamma
View all literature mentionsThis monoclonal targets beta-Tubulin
View all literature mentionsThis monoclonal targets alpha-Tubulin
View all literature mentionsThis monoclonal targets FLAG
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View all literature mentionsThis polyclonal targets Citrine, EGFP, GFP, YFP
View all literature mentionsThis monoclonal targets GAPDH
View all literature mentionsCell line HeLa is a Cancer cell line with a species of origin Homo sapiens
View all literature mentionsCell line HEK293T is a Transformed cell line with a species of origin Homo sapiens (Human)
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