scholarly journals Metaphase kinetochore movements are regulated by kinesin-8 motors and microtubule dynamic instability

2018 ◽  
Vol 29 (11) ◽  
pp. 1332-1345 ◽  
Author(s):  
Anna H. Klemm ◽  
Agneza Bosilj ◽  
Matko Gluncˇic´ ◽  
Nenad Pavin ◽  
Iva M. Tolic´
Keyword(s):  
Theoretical Model ◽  
Physical Mechanism ◽  
Dynamic Instability ◽  
Protein Complexes ◽  
Spindle Pole ◽  
Wild Type ◽  
Microtubule Dynamic ◽  
Spindle Poles ◽  
Sister Chromatids ◽  
Pulling Forces

During metaphase, sister chromatids are connected to microtubules extending from the opposite spindle poles via kinetochores to protein complexes on the chromosome. Kinetochores congress to the equatorial plane of the spindle and oscillate around it, with kinesin-8 motors restricting these movements. Yet, the physical mechanism underlying kinetochore movements is unclear. We show that kinetochore movements in the fission yeast Schizosaccharomyces pombe are regulated by kinesin-8-promoted microtubule catastrophe, force-induced rescue, and microtubule dynamic instability. A candidate screen showed that among the selected motors only kinesin-8 motors Klp5/Klp6 are required for kinetochore centering. Kinesin-8 accumulates at the end of microtubules, where it promotes catastrophe. Laser ablation of the spindle resulted in kinetochore movement toward the intact spindle pole in wild-type and klp5Δ cells, suggesting that kinetochore movement is driven by pulling forces. Our theoretical model with Langevin description of microtubule dynamic instability shows that kinesin-8 motors are required for kinetochore centering, whereas sensitivity of rescue to force is necessary for the generation of oscillations. We found that irregular kinetochore movements occur for a broader range of parameters than regular oscillations. Thus, our work provides an explanation for how regulation of microtubule dynamic instability contributes to kinetochore congression and the accompanying movements around the spindle center.

scholarly journals Motile kinetochores and polar ejection forces dictate chromosome position on the vertebrate mitotic spindle

1994 ◽  
Vol 124 (3) ◽  
pp. 223-233 ◽  
Author(s):  
CL Rieder ◽  
ED Salmon
Keyword(s):  
Mitotic Spindle ◽  
Constant Velocity ◽  
Molecular Mechanisms ◽  
Dynamic Instability ◽  
Microtubule Dynamic ◽  
Pole Motion ◽  
Microtubule Motors ◽  
Chromosome Position ◽  
Pulling Forces

We argue that hypotheses for how chromosomes achieve a metaphase alignment, that are based solely on a tug-of-war between poleward pulling forces produced along the length of opposing kinetochore fibers, are no longer tenable for vertebrates. Instead, kinetochores move themselves and their attached chromosomes, poleward and away from the pole, on the ends of relatively stationary but shortening/elongating kinetochore fiber microtubules. Kinetochores are also "smart" in that they switch between persistent constant-velocity phases of poleward and away from the pole motion, both autonomously and in response to information within the spindle. Several molecular mechanisms may contribute to this directional instability including kinetochore-associated microtubule motors and kinetochore microtubule dynamic instability. The control of kinetochore directional instability, to allow for congression and anaphase, is likely mediated by a vectorial mechanism whose magnitude and orientation depend on the density and orientation or growth of polar microtubules. Polar microtubule arrays have been shown to resist chromosome poleward motion and to push chromosomes away from the pole. These "polar ejection forces" appear to play a key role in regulating kinetochore directional instability, and hence, positions achieved by chromosomes on the spindle.

scholarly journals Nsk1 ensures accurate chromosome segregation by promoting association of kinetochores to spindle poles during anaphase B

2011 ◽  
Vol 22 (23) ◽  
pp. 4486-4502 ◽  
Author(s):  
Graham J. Buttrick ◽  
John C. Meadows ◽  
Theresa C. Lancaster ◽  
Vincent Vanoosthuyse ◽  
Lindsey A. Shepperd ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Growth Defect ◽  
Catalytic Subunits ◽  
Spindle Poles ◽  
Sister Chromatids ◽  
Anaphase B ◽  
Novel Protein

Type 1 phosphatase (PP1) antagonizes Aurora B kinase to stabilize kinetochore–microtubule attachments and to silence the spindle checkpoint. We screened for factors that exacerbate the growth defect of Δdis2 cells, which lack one of two catalytic subunits of PP1 in fission yeast, and identified Nsk1, a novel protein required for accurate chromosome segregation. During interphase, Nsk1 resides in the nucleolus but spreads throughout the nucleoplasm as cells enter mitosis. Following dephosphorylation by Clp1 (Cdc14-like) phosphatase and at least one other phosphatase, Nsk1 localizes to the interface between kinetochores and the inner face of the spindle pole body during anaphase. In the absence of Nsk1, some kinetochores become detached from spindle poles during anaphase B. If this occurs late in anaphase B, then the sister chromatids of unclustered kinetochores segregate to the correct daughter cell. These unclustered kinetochores are efficiently captured, retrieved, bioriented, and segregated during the following mitosis, as long as Dis2 is present. However, if kinetochores are detached from a spindle pole early in anaphase B, then these sister chromatids become missegregated. These data suggest Nsk1 ensures accurate chromosome segregation by promoting the tethering of kinetochores to spindle poles during anaphase B.

scholarly journals Sld5 Ensures Centrosomal Resistance to Congression Forces by Preserving Centriolar Satellites

2017 ◽  
Vol 38 (2) ◽  
Author(s):  
Manpreet Kaur ◽  
Raksha Devi ◽  
Tanushree Ghosh ◽  
Md Muntaz Khan ◽  
Praveen Kumar ◽  
...  
Keyword(s):  
Dna Replication ◽  
Unknown Function ◽  
Motor Protein ◽  
Spindle Pole ◽  
Replication Protein ◽  
Traction Forces ◽  
Centrosomal Protein ◽  
Spindle Poles ◽  
Chromosome Congression ◽  
Pulling Forces

ABSTRACT The migration of chromosomes during mitosis is mediated primarily by kinesins that bind to the chromosomes and move along the microtubules, exerting pulling and pushing forces on the centrosomes. We report that a DNA replication protein, Sld5, localizes to the centrosomes, resisting the microtubular pulling forces experienced during chromosome congression. In the absence of Sld5, centriolar satellites, which normally cluster around the centrosomes, are dissipated throughout the cytoplasm, resulting in the loss of their known function of recruiting the centrosomal protein, pericentrin. We observed that Sld5-deficient centrosomes lacking pericentrin were unable to endure the CENP-E- and Kid-mediated microtubular forces that converge on the centrosomes during chromosome congression, resulting in monocentriolar and acentriolar spindle poles. The minus-end-directed kinesin-14 motor protein, HSET, sustains the traction forces that mediate centrosomal fragmentation in Sld5-depleted cells. Thus, we report that a DNA replication protein has an as yet unknown function of ensuring spindle pole resistance to traction forces exerted during chromosome congression.

scholarly journals Conservative Duplication of Spindle Poles during Meiosis in Saccharomyces cerevisiae

2001 ◽  
Vol 183 (7) ◽  
pp. 2372-2375 ◽  
Author(s):  
Andreas Wesp ◽  
Susanne Prinz ◽  
Gerald R. Fink
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Spore Formation ◽  
Wild Type ◽  
Body Distribution ◽  
Spindle Poles ◽  
Pole Body ◽  
Spindle Pole Bodies ◽  
Type Strains

ABSTRACT During sporulation in diploid Saccharomyces cerevisiae, spindle pole bodies acquire the so-called meiotic plaque, a prerequisite for spore formation. Mpc70p is a component of the meiotic plaque and is thus essential for spore formation. We show here that MPC70/mpc70 heterozygous strains most often produce two spores instead of four and that these spores are always nonsisters. In wild-type strains, Mpc70p localizes to all four spindle pole bodies, whereas in MPC70/mpc70 strains Mpc70p localizes to only two of the four spindle pole bodies, and these are always nonsisters. Our data can be explained by conservative spindle pole body distribution in which the two newly synthesized meiosis II spindle pole bodies of MPC70/mpc70 strains lack Mpc70p.

scholarly journals Chiasmata and the kinetochore component Dam1 are crucial for elimination of erroneous chromosome attachments and centromere oscillation at meiosis I

Open Biology ◽  
2021 ◽  
Vol 11 (2) ◽  
Author(s):  
Misuzu Wakiya ◽  
Eriko Nishi ◽  
Shinnosuke Kawai ◽  
Kohei Yamada ◽  
Kazuhiro Katsumata ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Spindle Pole ◽  
Oriented Attachment ◽  
Aurora B ◽  
Correction Factors ◽  
Homologous Chromosomes ◽  
Spindle Poles ◽  
Sister Chromatids ◽  
Potential Link ◽  
Meiosis I

Establishment of proper chromosome attachments to the spindle requires elimination of erroneous attachments, but the mechanism of this process is not fully understood. During meiosis I, sister chromatids attach to the same spindle pole (mono-oriented attachment), whereas homologous chromosomes attach to opposite poles (bi-oriented attachment), resulting in homologous chromosome segregation. Here, we show that chiasmata that link homologous chromosomes and kinetochore component Dam1 are crucial for elimination of erroneous attachments and oscillation of centromeres between the spindle poles at meiosis I in fission yeast. In chiasma-forming cells, Mad2 and Aurora B kinase, which provides time for attachment correction and destabilizes erroneous attachments, respectively, caused elimination of bi-oriented attachments of sister chromatids, whereas in chiasma-lacking cells, they caused elimination of mono-oriented attachments. In chiasma-forming cells, in addition, homologous centromere oscillation was coordinated. Furthermore, Dam1 contributed to attachment elimination in both chiasma-forming and chiasma-lacking cells, and drove centromere oscillation. These results demonstrate that chiasmata alter attachment correction patterns by enabling error correction factors to eliminate bi-oriented attachment of sister chromatids, and suggest that Dam1 induces elimination of erroneous attachments. The coincidental contribution of chiasmata and Dam1 to centromere oscillation also suggests a potential link between centromere oscillation and attachment elimination.

A requirement for the Abnormal Spindle protein to organise microtubules of the central spindle for cytokinesis inDrosophila

2002 ◽  
Vol 115 (5) ◽  
pp. 913-922 ◽  
Author(s):  
Maria Giovanna Riparbelli ◽  
Giuliano Callaini ◽  
David M. Glover ◽  
Maria do Carmo Avides
Keyword(s):  
Spindle Pole Body ◽  
Spindle Pole ◽  
Male Meiosis ◽  
Wild Type ◽  
Female Meiosis ◽  
Central Spindle ◽  
Spindle Poles ◽  
Late Anaphase ◽  
Mutant Cells ◽  
Sperm Aster

Drosophila abnormal spindle (asp) mutants exhibit a mitotic metaphase checkpoint arrest with abnormal spindle poles, which reflects a requirement for Asp for the integrity of microtubule organising centres (MTOCs). In male meiosis, the absence of a strong spindle integrity checkpoint enables asp mutant cells to proceed through anaphase and telophase. However, the central spindle region is not correctly organised and cells frequently fail to complete cytokinesis. This contrasts with meiosis in wild-type males where at late anaphase a dense array of microtubules forms in the central spindle region that has Asp localised at its border. We speculate that Asp is associated with the minus ends of microtubules that have been released from the spindle poles to form the central spindle. A parallel situation arises in female meiosis where Asp not only associates with the minus ends of microtubules at the acentriolar poles but also with the central spindle pole body that forms between the two tandem spindles of meiosis II. Upon fertilisation, Asp is also recruited to the MTOC that nucleates the sperm aster. Asp is required for growth of the microtubules of the sperm aster,which in asp mutants remains diminutive and so prevents migration of the pronuclei.

scholarly journals A Mutation in γ-Tubulin Alters Microtubule Dynamics and Organization and Is Synthetically Lethal with the Kinesin-like Protein Pkl1p

2000 ◽  
Vol 11 (4) ◽  
pp. 1225-1239 ◽  
Author(s):  
Janet L. Paluh ◽  
Eva Nogales ◽  
Berl R. Oakley ◽  
Kent McDonald ◽  
Alison L. Pidoux ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Three Dimensional ◽  
Time Lapse ◽  
Spindle Pole ◽  
Microtubule Dynamics ◽  
Wild Type ◽  
Protein Protein Interactions ◽  
Cytoplasmic Microtubule ◽  
Spindle Poles ◽  
Tubulin Protein

Mitotic segregation of chromosomes requires spindle pole functions for microtubule nucleation, minus end organization, and regulation of dynamics. γ-Tubulin is essential for nucleation, and we now extend its role to these latter processes. We have characterized a mutation in γ-tubulin that results in cold-sensitive mitotic arrest with an elongated bipolar spindle but impaired anaphase A. At 30°C cytoplasmic microtubule arrays are abnormal and bundle into single larger arrays. Three-dimensional time-lapse video microscopy reveals that microtubule dynamics are altered. Localization of the mutant γ-tubulin is like the wild-type protein. Prediction of γ-tubulin structure indicates that non-α/β-tubulin protein–protein interactions could be affected. The kinesin-like protein (klp)Pkl1p localizes to the spindle poles and spindle and is essential for viability of the γ-tubulin mutant and in multicopy for normal cell morphology at 30°C. Localization and function of Pkl1p in the mutant appear unaltered, consistent with a redundant function for this protein in wild type. Our data indicate a broader role for γ-tubulin at spindle poles in regulating aspects of microtubule dynamics and organization. We propose that Pkl1p rescues an impaired function of γ-tubulin that involves non-tubulin protein–protein interactions, presumably with a second motor, MAP, or MTOC component.

scholarly journals Mitotic Chromosome Biorientation in Fission Yeast Is Enhanced by Dynein and a Minus-end–directed, Kinesin-like Protein

2007 ◽  
Vol 18 (6) ◽  
pp. 2216-2225 ◽  
Author(s):  
Ekaterina L. Grishchuk ◽  
Ilia S. Spiridonov ◽  
J. Richard McIntosh
Keyword(s):  
Fission Yeast ◽  
Chromosome Segregation ◽  
Mitotic Chromosome ◽  
Spindle Pole ◽  
Ultrastructural Analysis ◽  
Yeast Cells ◽  
Mitotic Spindles ◽  
Wild Type ◽  
Spindle Poles ◽  
Spindle Microtubules

Chromosome biorientation, the attachment of sister kinetochores to sister spindle poles, is vitally important for accurate chromosome segregation. We have studied this process by following the congression of pole-proximal kinetochores and their subsequent anaphase segregation in fission yeast cells that carry deletions in any or all of this organism's minus end–directed, microtubule-dependent motors: two related kinesin 14s (Pkl1p and Klp2p) and dynein. None of these deletions abolished biorientation, but fewer chromosomes segregated normally without Pkl1p, and to a lesser degree without dynein, than in wild-type cells. In the absence of Pkl1p, which normally localizes to the spindle and its poles, the checkpoint that monitors chromosome biorientation was defective, leading to frequent precocious anaphase. Ultrastructural analysis of mutant mitotic spindles suggests that Pkl1p contributes to error-free biorientation by promoting normal spindle pole organization, whereas dynein helps to anchor a focused bundle of spindle microtubules at the pole.

scholarly journals Evidence for anaphase pulling forces during C. elegans meiosis

2020 ◽  
Vol 219 (12) ◽  
Author(s):  
Brennan M. Danlasky ◽  
Michelle T. Panzica ◽  
Karen P. McNally ◽  
Elizabeth Vargas ◽  
Cynthia Bailey ◽  
...  
Keyword(s):  
Spindle Pole ◽  
Outer Face ◽  
Chromosome Movement ◽  
Female Meiosis ◽  
Homologous Chromosomes ◽  
C Elegans ◽  
Spindle Poles ◽  
Pulling Forces ◽  
Spindle Elongation ◽  
Anaphase B

Anaphase chromosome movement is thought to be mediated by pulling forces generated by end-on attachment of microtubules to the outer face of kinetochores. However, it has been suggested that during C. elegans female meiosis, anaphase is mediated by a kinetochore-independent pushing mechanism with microtubules only attached to the inner face of segregating chromosomes. We found that the kinetochore proteins KNL-1 and KNL-3 are required for preanaphase chromosome stretching, suggesting a role in pulling forces. In the absence of KNL-1,3, pairs of homologous chromosomes did not separate and did not move toward a spindle pole. Instead, each homolog pair moved together with the same spindle pole during anaphase B spindle elongation. Two masses of chromatin thus ended up at opposite spindle poles, giving the appearance of successful anaphase.

scholarly journals Pivot-and-bond model explains microtubule bundle formation

2017 ◽  
Author(s):  
Marcel Prelogović ◽  
Lora Winters ◽  
Ana Milas ◽  
Iva M. Tolić ◽  
Nenad Pavin
Keyword(s):  
Fission Yeast ◽  
Physical Mechanism ◽  
Spindle Pole ◽  
Yeast Cells ◽  
Cross Linking ◽  
Stable Bundle ◽  
Wild Type ◽  
Microtubule Bundle ◽  
Angular Movement ◽  
Bond Model

ABSTRACTDuring mitosis, bundles of microtubules form a spindle, but the physical mechanism of bundle formation is still not known. Here we show that random angular movement of microtubules around the spindle pole and forces exerted by passive cross-linking proteins are sufficient for the formation of stable microtubule bundles. We test these predictions by experiments in wild-type and ase1Δ fission yeast cells. In conclusion, the angular motion drives the alignment of microtubules, which in turn allows the cross-linking proteins to connect the microtubules into a stable bundle.

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