scholarly journals Automated tracking of mitotic spindle pole positions shows that LGN is required for spindle rotation but not orientation maintenance

Cell Cycle ◽  
2013 ◽  
Vol 12 (16) ◽  
pp. 2643-2655 ◽  
Author(s):  
Adam M Corrigan ◽  
Roshan L Shrestha ◽  
Ihsan Zulkipli ◽  
Noriko Hiroi ◽  
Yingjun Liu ◽  
...  
Keyword(s):  
Mitotic Spindle ◽  
Spindle Pole ◽  
Automated Tracking ◽  
Spindle Rotation ◽  
Mitotic Spindle Pole

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 Aurora-A inactivation causes mitotic spindle pole fragmentation by unbalancing microtubule-generated forces

2011 ◽  
Vol 10 (1) ◽  
pp. 131 ◽  
Author(s):  
Italia A Asteriti ◽  
Maria Giubettini ◽  
Patrizia Lavia ◽  
Giulia Guarguaglini
Keyword(s):  
Mitotic Spindle ◽  
Spindle Pole ◽  
Aurora A ◽  
Mitotic Spindle Pole

scholarly journals Chlamydia trachomatis Infection Causes Mitotic Spindle Pole Defects Independently from its Effects on Centrosome Amplification

Traffic ◽  
2011 ◽  
Vol 12 (7) ◽  
pp. 854-866 ◽  
Author(s):  
Andrea E. Knowlton ◽  
Heather M. Brown ◽  
Theresa S. Richards ◽  
Lauren A. Andreolas ◽  
Rahul K. Patel ◽  
...  
Keyword(s):  
Chlamydia Trachomatis ◽  
Mitotic Spindle ◽  
Spindle Pole ◽  
Centrosome Amplification ◽  
Chlamydia Trachomatis Infection ◽  
Mitotic Spindle Pole

scholarly journals A novel mitotic spindle pole component that originates from the cytoplasm during prophase.

1986 ◽  
Vol 103 (5) ◽  
pp. 1863-1872 ◽  
Author(s):  
P R Sager ◽  
N L Rothfield ◽  
J M Oliver ◽  
R D Berlin
Keyword(s):  
Mitotic Spindle ◽  
Spindle Pole ◽  
Early Prophase ◽  
Microtubule Organizing Center ◽  
Spindle Poles ◽  
Interphase Cells ◽  
Organizing Center ◽  
Mitotic Spindle Pole ◽  
Pole Component

Several unique aspects of mitotic spindle formation have been revealed by investigation of an autoantibody present in the serum of a patient with the CREST (calcinosis, Raynaud's phenomenon, esophageal dysmotility, schlerodacytyly, and telangiectasias) syndrome. This antibody was previously shown to label at the spindle poles of metaphase and anaphase cells and to be absent from interphase cells. We show here that the serum stained discrete cytoplasmic foci in early prophase cells and only later localized to the spindle poles. The cytoplasmic distribution of the antigen was also seen in nocodazole-arrested cells and prophase cells in populations treated with taxol. In normal and taxol-treated cells, the microtubules appeared to emanate from the cytoplasmic foci and polar stain, and in cells released from nocodazole block, microtubules regrew from antigen-containing centers. This characteristic distribution suggests that the antigen is part of a microtubule organizing center. Thus, we propose that a prophase originating polar antigen functions in spindle pole organization as a coalescing microtubule organizing center that is present only during mitosis. Characterization of the serum showed reactions with multiple proteins at 115, 110, 50, 36, 30, and 28 kD. However, affinity-eluted antibody from the 115/110-kD bands was shown to specifically label the spindle pole and cytosolic foci in prophase cells.

scholarly journals Differential responses of mitotic spindle pole formation to microtubule-stabilizing agents epothilones A and B at low concentrations

Cell Cycle ◽  
2008 ◽  
Vol 7 (4) ◽  
pp. 477-483 ◽  
Author(s):  
Shinji Sakaushi ◽  
Kumi Nishida ◽  
Takashi Fukada ◽  
Kaori Senda-Murata ◽  
Shigenori Oka ◽  
...  
Keyword(s):  
Mitotic Spindle ◽  
Spindle Pole ◽  
Stabilizing Agents ◽  
Low Concentrations ◽  
Differential Responses ◽  
Mitotic Spindle Pole

scholarly journals Importin-β negatively regulates multiple aspects of mitosis including RANGAP1 recruitment to kinetochores

2012 ◽  
Vol 196 (4) ◽  
pp. 435-450 ◽  
Author(s):  
Emanuele Roscioli ◽  
Laura Di Francesco ◽  
Alessio Bolognesi ◽  
Maria Giubettini ◽  
Serena Orlando ◽  
...  
Keyword(s):  
Mitotic Spindle ◽  
Binding Sites ◽  
Protein Import ◽  
Spindle Pole ◽  
Nuclear Pore ◽  
Microtubule Dynamic ◽  
Nuclear Envelope Breakdown ◽  
Microtubule Attachment ◽  
Importin Α ◽  
Mitotic Spindle Pole

Importin-β is the main vector for interphase nuclear protein import and plays roles after nuclear envelope breakdown. Here we show that importin-β regulates multiple aspects of mitosis via distinct domains that interact with different classes of proteins in human cells. The C-terminal region (which binds importin-α) inhibits mitotic spindle pole formation. The central region (harboring nucleoporin-binding sites) regulates microtubule dynamic functions and interaction with kinetochores. Importin-β interacts through this region with NUP358/RANBP2, which in turn binds SUMO-conjugated RANGAP1 in nuclear pores. We show that this interaction continues after nuclear pore disassembly. Overexpression of importin-β, or of the nucleoporin-binding region, inhibited RANGAP1 recruitment to mitotic kinetochores, an event that is known to require microtubule attachment and the exportin CRM1. Co-expressing either importin-β–interacting RANBP2 fragments, or CRM1, restored RANGAP1 to kinetochores and rescued importin-β–dependent mitotic dynamic defects. These results reveal previously unrecognized importin-β functions at kinetochores exerted via RANBP2 and opposed by CRM1.

A reevaluation of the mitotic spindle pole body cycle in Tilletia caries based on freeze-substitution techniques

1994 ◽  
Vol 72 (10) ◽  
pp. 1412-1423 ◽  
Author(s):  
Kerry O'donnell
Keyword(s):  
Electron Microscopy ◽  
Mitotic Spindle ◽  
Spindle Pole Body ◽  
Freeze Substitution ◽  
Spindle Pole ◽  
Metaphase Chromosomes ◽  
Tilletia Caries ◽  
Pole Body ◽  
The One ◽  
Mitotic Spindle Pole

Mitosis in the wheat pathogen Tilletia caries (Basidiomycota, Tilletiales) was investigated by electron microscopy of serially sectioned, fast-frozen, freeze-substituted mitotic cells called ballistospores. A duplicated spindle pole body consisting of two identical, three-layered globular elements connected by a middle piece was attached to the extranuclear face of each nucleus at interphase. During mitosis, astral and spindle microtubules radiated from the globular elements that form the poles of an intranuclear spindle. At metaphase, chromosomes were interspersed with the nonkinetochore microtubules, and they were spread along the central two-thirds of the spindle. Each chromatid was attached to a spindle pole by a single, continuous, kinetochore microtubule. Postmitotic replication of the spindle pole body occurred during late telophase to interphase. Results from this study are presented in the form of a model of the mitotic spindle pole body cycle in Tilletia, and this model is compared with the one previously reported for Tilletia and other basidiomycetes. Key words: electron microscopy, freeze substitution, mitosis, spindle pole body, Tilletia.

Role of gamma-tubulin in mitosis-specific microtubule nucleation from the Schizosaccharomyces pombe spindle pole body

1996 ◽  
Vol 109 (1) ◽  
pp. 165-177 ◽  
Author(s):  
H. Masuda ◽  
T. Shibata
Keyword(s):  
Protein Kinase ◽  
Mitotic Spindle ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Microtubule Nucleation ◽  
Amino Terminal ◽  
Pole Body ◽  
Gamma Tubulin ◽  
Mitotic Spindle Pole

The ability of the Schizosacchromyces pombe spindle pole body to nucleate microtubules is activated at the onset of mitosis for forming a mitotic spindle, but it is inactivated during interphase. We have previously developed an in vitro assay for studying the molecular mechanism of spindle pole body activation using permeabilized interphase S. pombe cells and Xenopus mitotic extracts. We have shown that the interphase spindle pole body is activated indirectly by p34cdc2 protein kinase in Xenopus mitotic extracts. In this study we examined the role of gamma-tubulin, a component of both interphase and mitotic spindle pole body, in formation of the microtubule nucleating complex at the mitotic spindle pole body. A polyclonal antibody specific to S. pombe gamma-tubulin inhibited both activation of the interphase spindle pole body and microtubule nucleation from the mitotic spindle pole body. Addition of bacterially expressed S. pombe gamma-tubulin or its amino-terminal fragments to Xenopus mitotic extracts inhibited spindle pole body activation. Affinity chromatography of partially fractionated Xenopus mitotic extracts with the amino-terminal fragment of S. pombe gamma-tubulin showed that fractions bound to the fragment supported the activation. The fractions did not contain Xenopus gamma-tubulin, showing that activation of the spindle pole body is not due to recruitment of Xenopus gamma-tubulin to the spindle pole body. The spindle pole body activation occurred in extracts depleted of p34cdc2 protein kinase or MAP kinase. The activity of the fractions bound to the fragment was inhibited by a protein kinase inhibitor, staurosporine. These results suggest that S. pombe gamma-tubulin is a component of the microtubule nucleating complex, and that the function of proteins that interact with gamma-tubulin is required for activation of the spindle pole body. We present possible models for the activation that convert the immature microtubule nucleating complex at interphase into the mature microtubule nucleating complex at mitosis.

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