Cooperative mechanisms of mitotic spindle formation

O’Connell, Christopher B.; Khodjakov, Alexey

doi:10.1242/jcs.03442

Cited by 174 publications

(171 citation statements)

References 52 publications

(68 reference statements)

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“…The defects in spindle organization we find are consistent with this effect because we see a significant increase in short MTs near poles, which is likely due to stabilization of the plus ends of spindle MTs that grow toward the spindle equator. This type of biased MT growth toward the chromosomes has been demonstrated in studies tracking GFP-EB1 in the spindle (Piehl and Cassimeris, 2003) and may be due to stabilization of MTs near chromosomes based on the Ran-GTP gradient (Wollman et al, 2005;Bastiaens et al, 2006;Kalab et al, 2006;O'Connell and Khodjakov, 2007;Kalab and Heald, 2008). Alternatively, the increase in MTs near the poles could be a result of an increase in nucleation of MTs from the centrosome as paclitaxel has been shown to affect the MT nucleation rate (Schiff and Horwitz, 1981).…”

Section: What Is the Relationship Between Spindle Mt Dynamics And Orgmentioning

confidence: 85%

MCAK and Paclitaxel Have Differential Effects on Spindle Microtubule Organization and Dynamics

Rizk

Bohannon

Wetzel

et al. 2009

MBoC

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Within the mitotic spindle, there are multiple populations of microtubules with different turnover dynamics, but how these different dynamics are maintained is not fully understood. MCAK is a member of the kinesin-13 family of microtubule-destabilizing enzymes that is required for proper establishment and maintenance of the spindle. Using quantitative immunofluorescence and fluorescence recovery after photobleaching, we compared the differences in spindle organization caused by global suppression of microtubule dynamics, by treating cells with low levels of paclitaxel, versus specific perturbation of spindle microtubule subsets by MCAK inhibition. Paclitaxel treatment caused a disruption in spindle microtubule organization marked by a significant increase in microtubules near the poles and a reduction in K-fiber fluorescence intensity. This was correlated with a faster t 1/2 of both spindle and K-fiber microtubules. In contrast, MCAK inhibition caused a dramatic reorganization of spindle microtubules with a significant increase in astral microtubules and reduction in K-fiber fluorescence intensity, which correlated with a slower t 1/2 of K-fibers but no change in the t 1/2 of spindle microtubules. Our data support the model that MCAK perturbs spindle organization by acting preferentially on a subset of microtubules, and they support the overall hypothesis that microtubule dynamics is differentially regulated in the spindle. INTRODUCTIONThe cytoskeleton must undergo dramatic reorganization as cells transition from interphase to mitosis to assemble the mitotic spindle. The spindle is a macromolecular structure composed of a dynamic array of microtubules (MTs) and their associated proteins that is necessary for proper chromosome segregation (Compton, 2000;Walczak and Heald, 2008). At the onset of mitosis, there is an increase in MT turnover that allows for breakdown of the interphase array and assembly of the mitotic spindle (Saxton et al., 1984;. This change is correlated with an increased catastrophe frequency (transition from growth to shrinkage) and a decreased rescue frequency (transition from shrinkage to growth) (Belmont et al., 1990;Gliksman et al., 1992;Verde et al., 1992;Rusan et al., 2001). The changes in MT dynamics are also correlated with a change in MT polymer levels during mitosis (Zhai et al., 1996). At nuclear envelope breakdown, there is a dramatic decrease in MT polymer levels, which may allow the cell to rapidly assemble a mitotic spindle because the released tubulin dimers can polymerize into new spindle MTs. As the cell progresses from mitosis to the next interphase, there is no change in the levels of MT polymer (Zhai et al., 1996), suggesting that MT polymer gets reorganized to reform the interphase MT cytoskeleton, without a significant change in the dynamics of the MTs. These studies highlight the need for the cell to possess a mechanism to temporally regulate MT dynamics.In addition to the temporal changes in dynamics throughout the cell cycle, the dynamics of MTs within mitosis are also...

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Section: What Is the Relationship Between Spindle Mt Dynamics And Orgmentioning

confidence: 85%

MCAK and Paclitaxel Have Differential Effects on Spindle Microtubule Organization and Dynamics

Rizk

Bohannon

Wetzel

et al. 2009

MBoC

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“…During cell division, genetic integrity is maintained by ensuring that all chromosomes are attached to microtubules emanating from both poles of the mitotic spindle before segregation of sister chromatids begins (1). This process is monitored by the mitotic checkpoint, which prevents initiation of anaphase until every kinetochore is attached and tension between kinetochores of paired sister chromatids is sufficient, ensuring biorientation (2).…”

Section: Introductionmentioning

confidence: 99%

Caspase-3–Dependent Mitotic Checkpoint Inactivation by the Small-Molecule Inducers of Mitotic Slippage SU6656 and Geraldol

Riffell

Jänicke²,

Roberge³

2011

Molecular Cancer Therapeutics

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Microtubule-targeting cancer drugs such as paclitaxel block cell-cycle progression at mitosis by prolonged activation of the mitotic checkpoint. Cells can spontaneously escape mitotic arrest and enter interphase without chromosome segregation by a process termed mitotic slippage that involves the degradation of cyclin B1 without mitotic checkpoint inactivation. Inducing mitotic slippage with chemicals causes cells to die after multiple rounds of DNA replication without cell division, which may enhance the antitumor activity of microtubule-targeting drugs. Here, we explore pathways leading to mitotic slippage by using SU6656 and geraldol, two recently identified chemical inducers of mitotic slippage. Mitotic slippage induced by SU6656 or geraldol was blocked by the proteasome inhibitor MG-132 and involved proteasome-dependent degradation of cyclin B1 and the mitotic checkpoint proteins budding uninhibited by benzimidazole related 1 (BubR1) and cell division cycle 20 (Cdc20) in T98G cells. Mitotic slippage and the degradation of BubR1 and Cdc20 were also inhibited by the caspase-3 and -7 inhibitor DEVD-CHO.

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“…The second is a chromosome-dominated pathway found largely in female germline meiotic cells in which the chromosomes contribute to the assembly and stabilization of microtubules (MTs) that are then formed into bipolar, anastral spindles by the action of MT motor proteins. A large number of studies have used the in vitro Xenopus oocyte extract system to characterize both the centrosome-dependent and -independent pathways (Heald et al, 1997;Karsenti and Vernos, 2001; Karsenti and Nedelec, 2004;Mitchison et al, 2004) and the current view is that both of these processes contribute to the formation of the bipolar mitotic spindle in many animal cells (O'Connell and Khodjakov, 2007). In addition, recent studies suggest that the chromosomes may not be the only sites for MT assembly in acentrosomal systems in that MTs have been shown to grow from pieces of the nuclear envelope (Rebollo et al, 2004) as well as from the spindle itself (Mahoney et al, 2006), a process that may be at least partially based on MT severing (Srayko et al, 2006;McNally et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Bipolar, anastral spindle development in artificially activated sea urchin eggs

Henson

Fried

McClellan

et al. 2008

Developmental Dynamics

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The mitotic apparatus of the early sea urchin embryo is the archetype example of a centrosome-dominated, large aster spindle organized by means of the centriole of the fertilizing sperm. In this study, we tested the hypothesis that artificially activated sea urchin eggs possess the capacity to assemble the anastral, bipolar spindles present in many acentrosomal systems. Control fertilized Lytechinus pictus embryos and ammoniaactivated eggs were immunolabeled for tubulin, centrosomal material, the spindle pole structuring protein NuMA and the mitotic kinesins MKLP1/Kinesin-6, Eg5/Kinesin-5, and KinI/Kinesin-13. Confocal imaging showed that a subset of ammonia-activated eggs contained bipolar "mini-spindles" that were anastral; displayed metaphase and anaphase-like stages; labeled for centrosomal material, NuMA, and the three mitotic kinesins; and were observed in living eggs using polarization optics. These results suggest that spindle structural and motor proteins have the ability to organize bipolar, anastral spindles in sea urchin eggs activated in the absence of the paternal centriole. Developmental Dynamics 237:1348 -1358, 2008.

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Cooperative mechanisms of mitotic spindle formation

Cited by 174 publications

References 52 publications

MCAK and Paclitaxel Have Differential Effects on Spindle Microtubule Organization and Dynamics

MCAK and Paclitaxel Have Differential Effects on Spindle Microtubule Organization and Dynamics

Caspase-3–Dependent Mitotic Checkpoint Inactivation by the Small-Molecule Inducers of Mitotic Slippage SU6656 and Geraldol

Bipolar, anastral spindle development in artificially activated sea urchin eggs

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