A model for the proposed roles of different microtubule-based motor proteins in establishing spindle bipolarity

Walczak, Claire; Vernos, Isabelle; Mitchison, Timothy J.; Karsenti, Eric; Heald, Rebecca

doi:10.1016/s0960-9822(07)00370-3

Cited by 374 publications

(347 citation statements)

References 55 publications

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“…Second, centrosomes remained associated with the spindle, microtubule minus ends were focused at the poles, and spindles were bipolar indicating that inhibition of Kid function restored spindle pole organization to cells lacking NuMA function (compare Figures 1C to D and 3C to D). We hypothesized that spindle poles were organized in the absence of Kid and NuMA function by the activity of the kinesin-related protein HSET, which has been shown to cooperate with NuMA and cytoplasmic dynein in spindle organization (Walczak et al, 1998;Mountain et al, 1999;Gordon et al, 2001). To test this, we simultaneously injected cells with antibodies to NuMA, Kid, and HSET, and found that 90% of cells injected with all three antibodies displayed disorganized poles and unaligned chromosomes ( Figure 3E and Table 1).…”

Section: Spindle Pole Organization and Spindle Size Are Influenced Bymentioning

confidence: 99%

“…To test whether the lack of efficient chromosome alignment was specific to the perturbation of both Kid and NuMA, we simultaneously injected antibodies to Kid and either HSET or CENP-E. HSET is a kinesin-related protein that cooperates with NuMA and cytoplasmic dynein in organizing microtubule minus ends at spindle poles (Walczak et al, 1998;Mountain et al, 1999;Gordon et al, 2001). We previously demonstrated that injection of HSET-specific an- tibodies perturbed HSET function, which disrupted spindle pole organization in the absence of either centrosomes or NuMA activity (Mountain et al, 1999;Gordon et al, 2001).…”

Section: Chromosome Alignment Requires Numa and Kid Activitiesmentioning

confidence: 99%

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A Functional Relationship between NuMA and Kid Is Involved in Both Spindle Organization and Chromosome Alignment in Vertebrate Cells

Levesque

Howard

Gordon

et al. 2003

MBoC

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We examined spindle morphology and chromosome alignment in vertebrate cells after simultaneous perturbation of the chromokinesin Kid and either NuMA, CENP-E, or HSET. Spindle morphology and chromosome alignment after simultaneous perturbation of Kid and either HSET or CENP-E were no different from when either HSET or CENP-E was perturbed alone. However, short bipolar spindles with organized poles formed after perturbation of both Kid and NuMA in stark contrast to splayed spindle poles observed after perturbation of NuMA alone. Spindles were disorganized if Kid, NuMA, and HSET were perturbed, indicating that HSET is sufficient for spindle organization in the absence of Kid and NuMA function. In addition, chromosomes failed to align efficiently at the spindle equator after simultaneous perturbation of Kid and NuMA despite appropriate kinetochore-microtubule interactions that generated chromosome movement at normal velocities. These data indicate that a functional relationship between the chromokinesin Kid and the spindle pole organizing protein NuMA influences spindle morphology, and we propose that this occurs because NuMA forms functional linkages between kinetochore and nonkinetochore microtubules at spindle poles. In addition, these data show that both Kid and NuMA contribute to chromosome alignment in mammalian cells.

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Section: Spindle Pole Organization and Spindle Size Are Influenced Bymentioning

confidence: 99%

Section: Chromosome Alignment Requires Numa and Kid Activitiesmentioning

confidence: 99%

A Functional Relationship between NuMA and Kid Is Involved in Both Spindle Organization and Chromosome Alignment in Vertebrate Cells

Levesque

Howard

Gordon

et al. 2003

MBoC

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“…Given the high similarity between Nek6 and Nek7, it is plausible that Eg5 is also targeted by Nek7 kinase. It is thus possible that at least part of Nek7 À/À mitotic phenotypes are due to a disturbance in one or more of the multiple mitotic tasks performed by Eg5 (Walczak et al, 1998). Interestingly, overexpression of Eg5 in transgenic mice resulted in tetraploidization, aneuploidy and high incidence of cancers (Castillo et al, 2007).…”

Section: Nek7 Kinase Targeting Leads To Polyploidy H Salem Et Almentioning

confidence: 99%

Nek7 kinase targeting leads to early mortality, cytokinesis disturbance and polyploidy

et al. 2010

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The mammalian NIMA-related kinases (Neks) are commonly referred to as mitotic kinases, although a definitive in vivo verification of this definition is largely missing. Reduction in the activity of Nek7 or its close paralog, Nek6, has previously been shown to arrest cells in mitosis, mainly at metaphase. In this study, we investigate the developmental and cellular roles of Nek7 kinase through the generation and analysis of Nek7-deficient mice. We show that absence of Nek7 leads to lethality in late embryogenesis or at early post-natal stages and to severe growth retardation. Mouse embryonic fibroblasts (MEFs) derived from Nek7 À/À embryos show increase tendency for chromosomal lagging, micronuclei formation and cytokinesis failure. Tetraploidy and aneuploidy were commonly observed and their prevalence arises with MEFs passages. The frequency of multicentrosomal cells in the mutant's MEF cells was higher, and it commonly occurred concurrently with a binuclear phenotype, suggesting cytokinesis failure etiology. Lastly, the percentage of mutant MEF cells bearing primary cilia (PC) was low, whereas a cell population having two cilia appeared in the mutant MEFs. Taken together, these results confirm Nek7 as a regulator of cell division, and reveal it as an essential component for mammalian growth and survival. The intimate connection between tetraploidy, aneuploidy and cancer development suggests that Nek7 deregulation can induce oncogenesis.

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“…However, mitotic spindles can form in the absence of centrosomes through actions of motor proteins and structural elements (Theirkauf and Hawley, 1992;Bartolini and Gundersen, 2006;Walczak et al, 1998;Compton, 1998;McKim and Hawley, 1995;Matthies et al, 1996;Heald et al, 1997). It is commonly believed that centrosome functions have not been fully elucidated.…”

Section: Growing Evidence Of Centrosomal Checkpoints Responding To Dnmentioning

confidence: 99%

An ATM- and ATR-dependent checkpoint inactivates spindle assembly by targeting CEP63

Smith¹,

Dejsuphong

Balestrini³

et al. 2009

Nat Cell Biol

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The effects of ATM and ATR signalling induced by chromosomal breakage have been described extensively in modulating cell cycle progression up to the onset of mitosis.However, DNA damage checkpoint responses in mitotic cells are not well understood.This thesis reports on the effects of double strand breaks on the progression of mitosis.We found ATM and ATR activation can occur in mitotic Xenopus laevis egg extract and the induction of ATM and ATR by chromosomal breakages inhibits spindle assembly in both Xenopus egg extract and somatic cells. The delay in mitotic progression induced by ATM and ATR was found not to involve major spindle assembly factors activities such as, Cdk1, Plx1 and RCC1/Ran-GTP. However, normal anastral spindles formation around linear DNA coated beads, which can activate ATM and ATR, linked centrosome-driven spindle assembly to ATM and ATR dependent spindle defects. cDNA expression library screening was undertaken to identify novel ATM and ATR targets in this mitotic checkpoint pathway, through which the novel centrosomal protein XCEP63 was identified as a likely candidate. Data obtained from depletion and reconstitution of XCEP63 in Xenopus egg extract established that normal centrosome-driven spindle assembly requires XCEP63. Moreover, ATM and ATR phosphorylates XCEP63 on serine 560 and promotes delocalisation from the centrosome. ATM and ATR inhibition or addition of non-phosphorylable XCEP63 recombinant protein mutated at serine 560 prevents spindle assembly abnormalities.These findings suggest that ATM and ATR regulate mitotic events by targeting XCEP63 and centrosome-dependent spindle assembly. This pathway may provide support for DNA repair processes or regulate cell survival in the presence of mitotic DNA damage. 3

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A model for the proposed roles of different microtubule-based motor proteins in establishing spindle bipolarity

Abstract: Multiple microtubule-based motor activities are required for the bipolar organization of microtubules around chromatin beads, and we propose a model for the roles of the individual motor proteins in this process.

Cited by 374 publications

References 55 publications

A Functional Relationship between NuMA and Kid Is Involved in Both Spindle Organization and Chromosome Alignment in Vertebrate Cells

A Functional Relationship between NuMA and Kid Is Involved in Both Spindle Organization and Chromosome Alignment in Vertebrate Cells

Nek7 kinase targeting leads to early mortality, cytokinesis disturbance and polyploidy

An ATM- and ATR-dependent checkpoint inactivates spindle assembly by targeting CEP63

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