Cytochalasin J treatment significantly alters mitotic spindle microtubule organization and kinetochore structure in PtK1 cells

1997 ◽  
Vol 36 (2) ◽  
pp. 112-124 ◽  
Author(s):  
Gregory A. Wrench ◽  
Judith A. Snyder
Keyword(s):  
Mitotic Spindle ◽  
Microtubule Organization ◽  
Spindle Microtubule

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

2009 ◽  
Vol 20 (6) ◽  
pp. 1639-1651 ◽  
Author(s):  
Rania S. Rizk ◽  
Kevin P. Bohannon ◽  
Laura A. Wetzel ◽  
James Powers ◽  
Sidney L. Shaw ◽  
...  
Keyword(s):  
Fluorescence Intensity ◽  
Mitotic Spindle ◽  
Fluorescence Recovery After Photobleaching ◽  
Microtubule Dynamics ◽  
Microtubule Organization ◽  
Spindle Microtubule ◽  
Quantitative Immunofluorescence ◽  
Spindle Microtubules ◽  
Low Levels ◽  
Paclitaxel Treatment

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 t1/2 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 t1/2 of K-fibers but no change in the t1/2 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.

AtNUF2 modulates spindle microtubule organization and chromosome segregation during mitosis

2021 ◽  
Author(s):  
Jin Li ◽  
Yutao Wang ◽  
Wenxuan Zou ◽  
Liufang Jian ◽  
Ying Fu ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Microtubule Organization ◽  
Spindle Microtubule

scholarly journals Synergistic role of fission yeast Alp16GCP6 and Mzt1MOZART1 in γ-tubulin complex recruitment to mitotic spindle pole bodies and spindle assembly

2016 ◽  
Vol 27 (11) ◽  
pp. 1753-1763 ◽  
Author(s):  
Hirohisa Masuda ◽  
Takashi Toda
Keyword(s):  
Fission Yeast ◽  
Mitotic Spindle ◽  
Spindle Assembly Checkpoint ◽  
Synthetic Lethality ◽  
Spindle Assembly ◽  
Spindle Pole ◽  
Microtubule Assembly ◽  
Spindle Microtubule ◽  
Spindle Pole Bodies ◽  
Mitotic Spindle Pole

In fission yeast, γ-tubulin ring complex (γTuRC)–specific components Gfh1GCP4, Mod21GCP5, and Alp16GCP6 are nonessential for cell growth. Of these deletion mutants, only alp16Δ shows synthetic lethality with temperature-sensitive mutants of Mzt1MOZART1, a component of the γTuRC required for recruitment of the complex to microtubule-organizing centers. γ-Tubulin small complex levels at mitotic spindle pole bodies (SPBs, the centrosome equivalent in fungi) and microtubule levels for preanaphase spindles are significantly reduced in alp16Δ cells but not in gfh1Δ or mod21Δ cells. Furthermore, alp16Δ cells often form monopolar spindles and frequently lose a minichromosome when the spindle assembly checkpoint is inactivated. Alp16GCP6 promotes Mzt1-dependent γTuRC recruitment to mitotic SPBs and enhances spindle microtubule assembly in a manner dependent on its expression levels. Gfh1GCP4 and Mod21GCP5 are not required for Alp16GCP6-dependent γTuRC recruitment. Mzt1 has an additional role in the activation of the γTuRC for spindle microtubule assembly. The ratio of Mzt1 to γTuRC levels for preanaphase spindles is higher than at other stages of the cell cycle. Mzt1 overproduction enhances spindle microtubule assembly without affecting γTuRC levels at mitotic SPBs. We propose that Alp16GCP6 and Mzt1 act synergistically for efficient bipolar spindle assembly to ensure faithful chromosome segregation.

scholarly journals Centrophilin: a novel mitotic spindle protein involved in microtubule nucleation.

1991 ◽  
Vol 112 (3) ◽  
pp. 427-440 ◽  
Author(s):  
A Tousson ◽  
C Zeng ◽  
B R Brinkley ◽  
M M Valdivia
Keyword(s):  
Mitotic Spindle ◽  
Cell Extract ◽  
High Molecular Mass ◽  
Spindle Microtubule ◽  
Hela Cell Extract ◽  
Nucleation Sites ◽  
Pericentriolar Material ◽  
Aggregation And Disaggregation ◽  
Microtubule Growth ◽  
Novel Protein

A novel protein has been identified which may serve a key function in nucleating spindle microtubule growth in mitosis. This protein, called centrophilin, is sequentially relocated from the centromeres to the centrosomes to the midbody in a manner dependent on the mitotic phase. Centrophilin was initially detected by immunofluorescence with a monoclonal, primate-specific antibody (2D3) raised against kinetochore-enriched chromosome extract from HeLa cells (Valdivia, M. M., and B. R. Brinkley. 1985. J. Cell Biol. 101:1124-1134). Centrophilin forms prominent crescents at the poles of the metaphase spindle, gradually diminishes during anaphase, and bands the equatorial ends of midbody microtubules in telophase. The formation and breakdown of the spindle and midbody correlates in time and space with the aggregation and disaggregation of centrophilin foci. Immunogold EM reveals that centrophilin is a major component of pericentriolar material in metaphase. During recovery from microtubule inhibition, centrophilin foci act as nucleation sites for the assembly of spindle tubules. The 2D3 probe recognizes two high molecular mass polypeptides, 180 and 210 kD, on immunoblots of whole HeLa cell extract. Taken together, these data and the available literature on microtubule dynamics point inevitably to a singular model for control of spindle tubule turnover.

scholarly journals Action at a distance during cytokinesis

2009 ◽  
Vol 187 (6) ◽  
pp. 831-845 ◽  
Author(s):  
George von Dassow ◽  
Koen J.C. Verbrugghe ◽  
Ann L. Miller ◽  
Jenny R. Sider ◽  
William M. Bement
Keyword(s):  
Cell Surface ◽  
Mitotic Spindle ◽  
Cortical Microtubule ◽  
Live Imaging ◽  
Animal Cells ◽  
Microtubule Organization ◽  
Normal Cells ◽  
Accuracy And Precision ◽  
Action At A Distance ◽  
The Relationship

Animal cells decide where to build the cytokinetic apparatus by sensing the position of the mitotic spindle. Reflecting a long-standing presumption that a furrow-inducing stimulus travels from spindle to cortex via microtubules, debate continues about which microtubules, and in what geometry, are essential for accurate cytokinesis. We used live imaging in urchin and frog embryos to evaluate the relationship between microtubule organization and cytokinetic furrow position. In normal cells, the cytokinetic apparatus forms in a region of lower cortical microtubule density. Remarkably, cells depleted of astral microtubules conduct accurate, complete cytokinesis. Conversely, in anucleate cells, asters alone can support furrow induction without a spindle, but only when sufficiently separated. Ablation of a single centrosome displaces furrows away from the remaining centrosome; ablation of both centrosomes causes broad, inefficient furrowing. We conclude that the asters confer accuracy and precision to a primary furrow-inducing signal that can reach the cell surface from the spindle without transport on microtubules.

scholarly journals The kinesin-8 Kip3 scales anaphase spindle length by suppression of midzone microtubule polymerization

2014 ◽  
Vol 204 (6) ◽  
pp. 965-975 ◽  
Author(s):  
Rania S. Rizk ◽  
Katherine A. DiScipio ◽  
Kathleen G. Proudfoot ◽  
Mohan L. Gupta
Keyword(s):  
Mitotic Spindle ◽  
Molecular Mechanisms ◽  
Spindle Microtubule ◽  
Microtubule Polymerization ◽  
Sister Chromatids ◽  
Final Length ◽  
Spindle Microtubules ◽  
Spindle Elongation ◽  
Spindle Function ◽  
Yeast Mutants

Mitotic spindle function is critical for cell division and genomic stability. During anaphase, the elongating spindle physically segregates the sister chromatids. However, the molecular mechanisms that determine the extent of anaphase spindle elongation remain largely unclear. In a screen of yeast mutants with altered spindle length, we identified the kinesin-8 Kip3 as essential to scale spindle length with cell size. Kip3 is a multifunctional motor protein with microtubule depolymerase, plus-end motility, and antiparallel sliding activities. Here we demonstrate that the depolymerase activity is indispensable to control spindle length, whereas the motility and sliding activities are not sufficient. Furthermore, the microtubule-destabilizing activity is required to counteract Stu2/XMAP215-mediated microtubule polymerization so that spindle elongation terminates once spindles reach the appropriate final length. Our data support a model where Kip3 directly suppresses spindle microtubule polymerization, limiting midzone length. As a result, sliding forces within the midzone cannot buckle spindle microtubules, which allows the cell boundary to define the extent of spindle elongation.

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