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Salas-Pino S, Daga RR. Spatiotemporal control of spindle disassembly in fission yeast. Cell Mol Life Sci 2019; 76:3543-3551. [PMID: 31129857 PMCID: PMC11105212 DOI: 10.1007/s00018-019-03139-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 04/29/2019] [Accepted: 05/07/2019] [Indexed: 12/20/2022]
Abstract
Maintenance of genomic stability during cell division is one of the most important cellular tasks, and it critically depends on the faithful replication of the genetic material and its equal partitioning into daughter cells, gametes, or spores in the case of yeasts. Defective mitotic spindle assembly and disassembly both result in changes in cellular ploidy that ultimately impinge proliferation fitness and might increase tumor malignancy. Although a great progress has been made in understanding how spindles are assembled to orchestrate chromosome segregation, much less is known about how they are disassembled once completed their function. Here, we review two recently uncovered mechanisms of spindle disassembly that operate at different stages of the fission yeast life cycle.
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Affiliation(s)
- Silvia Salas-Pino
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas-Junta de Andalucia, Carretera de Utrera, km1, 41013, Seville, Spain.
| | - Rafael R Daga
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas-Junta de Andalucia, Carretera de Utrera, km1, 41013, Seville, Spain.
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2
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Abstract
Cells sense biochemical, electrical, and mechanical cues in their environment that affect their differentiation and behavior. Unlike biochemical and electrical signals, mechanical signals can propagate without the diffusion of proteins or ions; instead, forces are transmitted through mechanically stiff structures, flowing, for example, through cytoskeletal elements such as microtubules or filamentous actin. The molecular details underlying how cells respond to force are only beginning to be understood. Here we review tools for probing force-sensitive proteins and highlight several examples in which forces are transmitted, routed, and sensed by proteins in cells. We suggest that local unfolding and tension-dependent removal of autoinhibitory domains are common features in force-sensitive proteins and that force-sensitive proteins may be commonplace wherever forces are transmitted between and within cells. Because mechanical forces are inherent in the cellular environment, force is a signal that cells must take advantage of to maintain homeostasis and carry out their functions.
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Affiliation(s)
- Erik C Yusko
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195-7290
| | - Charles L Asbury
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195-7290
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3
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Sandquist JC, Kita AM, Bement WM. And the dead shall rise: actin and myosin return to the spindle. Dev Cell 2011; 21:410-9. [PMID: 21920311 DOI: 10.1016/j.devcel.2011.07.018] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 07/27/2011] [Accepted: 07/29/2011] [Indexed: 10/17/2022]
Abstract
The spindle directs chromosome partitioning in eukaryotes and, for the last three decades, has been considered primarily a structure based on microtubules, microtubule motors, and other microtubule binding proteins. However, a surprisingly large body of both old and new studies suggests roles for actin filaments (F-actin) and myosins (F-actin-based motor proteins) in spindle assembly and function. Here we review these data and conclude that in several cases the evidence for the participation of F-actin and myosins in spindle function is very strong, and in the situations where it is less strong, there is nevertheless enough evidence to warrant further investigation.
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Affiliation(s)
- Joshua C Sandquist
- Department of Zoology, University of Wisconsin-Madison, Madison, WI 53706, USA.
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4
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Fong CS, Sato M, Toda T. Fission yeast Pcp1 links polo kinase-mediated mitotic entry to gamma-tubulin-dependent spindle formation. EMBO J 2010; 29:120-30. [PMID: 19942852 PMCID: PMC2788132 DOI: 10.1038/emboj.2009.331] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Accepted: 10/16/2009] [Indexed: 12/23/2022] Open
Abstract
The centrosomal pericentrin-related proteins play pivotal roles in various aspects of cell division; however their underlying mechanisms remain largely elusive. Here we show that fission-yeast pericentrin-like Pcp1 regulates multiple functions of the spindle pole body (SPB) through recruiting two critical factors, the gamma-tubulin complex (gamma-TuC) and polo kinase (Plo1). We isolated two pcp1 mutants (pcp1-15 and pcp1-18) that display similar abnormal spindles, but with remarkably different molecular defects. Both mutants exhibit defective monopolar spindle microtubules that emanate from the mother SPB. However, while pcp1-15 fails to localise the gamma-TuC to the mitotic SPB, pcp1-18 is specifically defective in recruiting Plo1. Consistently Pcp1 forms a complex with both gamma-TuC and Plo1 in the cell. pcp1-18 is further defective in the mitotic-specific reorganisation of the nuclear envelope (NE), leading to impairment of SPB insertion into the NE. Moreover pcp1-18, but not pcp1-15, is rescued by overproducing nuclear pore components or advancing mitotic onset. The central role for Pcp1 in orchestrating these processes provides mechanistic insight into how the centrosome regulates multiple cellular pathways.
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Affiliation(s)
- Chii Shyang Fong
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, London, UK
| | - Masamitsu Sato
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, London, UK
| | - Takashi Toda
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, London, UK
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5
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Saitoh S, Kobayashi Y, Ogiyama Y, Takahashi K. Dual regulation of Mad2 localization on kinetochores by Bub1 and Dam1/DASH that ensure proper spindle interaction. Mol Biol Cell 2008; 19:3885-97. [PMID: 18632983 DOI: 10.1091/mbc.e08-03-0298] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The spindle assembly checkpoint monitors the state of spindle-kinetochore interaction to prevent premature onset of anaphase. Although checkpoint proteins, such as Mad2, are localized on kinetochores that do not interact properly with the spindle, it remains unknown how the checkpoint proteins recognize abnormalities in spindle-kinetochore interaction. Here, we report that Mad2 localization on kinetochores in fission yeast is regulated by two partially overlapping but distinct pathways: the Dam1/DASH and the Bub1 pathways. We show that Mad2 is localized on "unattached" as well as "tensionless" kinetochores. Our observations suggest that Bub1 is required for Mad2 to detect tensionless kinetochores, whereas Dam1/DASH is crucial for Mad2 to detect unattached kinetochores. In cells lacking both Bub1 and Dam1/DASH, Mad2 localization on kinetochores is diminished, and mitotic progression appears to be accelerated despite the frequent occurrence of abnormal chromosome segregation. Furthermore, we found that Dam1/DASH is required for promotion of spindle association with unattached kinetochores. In contrast, there is accumulating evidence that Bub1 is involved in resolution of erroneous spindle attachment on tensionless kinetochores. These pathways may act as molecular sensors determining the state of spindle association on each kinetochore, enabling proper regulation of the checkpoint activation as well as promotion/resolution of spindle attachment.
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Affiliation(s)
- Shigeaki Saitoh
- Division of Cell Biology, Institute of Life Science, Kurume University, Kurume, Fukuoka 839-0864, Japan.
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6
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Meadows JC, Millar J. Latrunculin A delays anaphase onset in fission yeast by disrupting an Ase1-independent pathway controlling mitotic spindle stability. Mol Biol Cell 2008; 19:3713-23. [PMID: 18562692 DOI: 10.1091/mbc.e08-02-0164] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
It has been proposed previously that latrunculin A, an inhibitor of actin polymerization, delays the onset of anaphase by causing spindle misorientation in fission yeast. However, we show that Delta mto1 cells, which are defective in nucleation of cytoplasmic microtubules, have profoundly misoriented spindles but are not delayed in the timing of sister chromatid separation, providing compelling evidence that fission yeast does not possess a spindle orientation checkpoint. Instead, we show that latrunculin A delays anaphase onset by disrupting interpolar microtubule stability. This effect is abolished in a latrunculin A-insensitive actin mutant and exacerbated in cells lacking Ase1, which cross-links antiparallel interpolar microtubules at the spindle midzone both before and after anaphase. These data indicate that both Ase1 and an intact actin cytoskeleton are required for preanaphase spindle stability. Finally, we show that loss of Ase1 activates a checkpoint that requires only the Mad3, Bub1, and Mph1, but not Mad1, Mad2, or Bub3 checkpoint proteins.
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Affiliation(s)
- John C Meadows
- Division of Yeast Genetics, National Institute for Medical Research, London NW7 1AA, United Kingdom
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7
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Tange Y, Niwa O. Schizosaccharomyces pombe Bub3 is dispensable for mitotic arrest following perturbed spindle formation. Genetics 2008; 179:785-92. [PMID: 18505884 PMCID: PMC2429874 DOI: 10.1534/genetics.107.081695] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2007] [Accepted: 04/07/2008] [Indexed: 11/18/2022] Open
Abstract
The core proteins of the spindle assembly checkpoint (SAC), Mads, Bubs, and Mps1, first identified in the budding yeast, are thought to be functionally and structurally conserved through evolution. We found that fission yeast Bub3 is dispensable for SAC, as bub3 null mutants blocked mitotic progression when spindle formation was disrupted. Consistently, the bub3 mutation only weakly affected the stability of minichromosome Ch16 compared with other SAC mutants. Fission yeast Rae1 has sequence homology with Bub3. The bub3 rae1 double mutant and rae1 single mutant did not have defective SAC, suggesting that these genes do not have overlapping roles for SAC. Observations of living cells revealed that the duration of the mitotic prometaphase/metaphase was longer in the bub3 mutant and was Mad2 dependent. Further, the bub3 mutant was defective in sister centromere association during metaphase. Together, these findings suggest that fission yeast Bub3 is required for normal spindle dynamics, but not for SAC.
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Affiliation(s)
- Yoshie Tange
- Kazusa DNA Research Institute, Kisarazu, Chiba 292-0818, Japan
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8
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Huang Y, Tran P, Oliferenko S, Balasubramanian MK. Assembly of microtubules and actomyosin rings in the absence of nuclei and spindle pole bodies revealed by a novel genetic method. PLoS One 2007; 2:e618. [PMID: 17637834 PMCID: PMC1913206 DOI: 10.1371/journal.pone.0000618] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2007] [Accepted: 06/11/2007] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The nucleus and the centrosomes (spindle pole bodies; SPBs in yeast) are believed to play key roles in the organization of various cellular structures, such as the actomyosin ring and microtubules. The ability to generate cells lacking nuclei and centrosomes (SPBs) is key to the elucidation of the role of these structures in various cellular processes. METHODOLOGY/PRINCIPAL FINDINGS Here we describe a genetic method, using the Schizosaccharomyces pombe cdc16-116 mutant, to reliably and efficiently generate fission yeast cells lacking nuclei and SPBs. We use this approach to show that the assembly of microtubules does not require nuclear associated microtubule organizing centers and SPBs. We also show that actomyosin rings can assemble albeit inefficiently in the absence of nuclei and SPBs. CONCLUSION We conclude that key cytoskeletal elements can be assembled in the absence of nuclei and SPBs. In addition, the approach we describe, taken together with physical approaches such as centrifugation, should facilitate the investigation of the role of the nucleus and SPBs in the assembly and inheritance of various cellular structures and organelles.
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Affiliation(s)
- Yinyi Huang
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore
| | - P.T. Tran
- Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Snezhana Oliferenko
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore
| | - Mohan K. Balasubramanian
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore
- * To whom correspondence should be addressed. E-mail:
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9
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Abstract
During the cell cycle of the fission yeast Schizosaccharomyces pombe, striking changes in the organization of the cytoplasmic microtubule cytoskeleton take place. These may serve as a model for understanding the different modes of microtubule organization that are often characteristic of differentiated higher eukaryotic cells. In the last few years, considerable progress has been made in our understanding of the organization and behaviour of fission yeast cytoplasmic microtubules, not only in the identification of the genes and proteins involved but also in the physiological analysis of function using fluorescently-tagged proteins in vivo. In this review we discuss the state of our knowledge in three areas: microtubule nucleation, regulation of microtubule dynamics and the organization and polarity of microtubule bundles. Advances in these areas provide a solid framework for a more detailed understanding of cytoplasmic microtubule organization.
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Affiliation(s)
- Kenneth E Sawin
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Swann Building, Mayfield Road, Edinburgh EH9 3JR, UK.
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10
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Vogel SK, Raabe I, Dereli A, Maghelli N, Tolić-Nørrelykke I. Interphase microtubules determine the initial alignment of the mitotic spindle. Curr Biol 2007; 17:438-44. [PMID: 17306542 DOI: 10.1016/j.cub.2007.01.047] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2006] [Revised: 01/10/2007] [Accepted: 01/17/2007] [Indexed: 11/18/2022]
Abstract
In the fission yeast Schizosaccharomyces pombe, interphase microtubules (MTs) position the nucleus [1, 2], which in turn positions the cell-division plane [1, 3]. It is unclear how the spindle orients, with respect to the predetermined division plane, to ensure that the chromosomes are segregated across this plane. It has been proposed that, during prometaphase, the astral MT interaction with the cell cortex aligns the spindle with the cell axis [4] and also participates in a spindle orientation checkpoint (SOC), which delays entry into anaphase as long as the spindle is misaligned [5-7]. Here, we trace the position of the spindle throughout mitosis in a single-cell assay. We find no evidence for the SOC. We show that the spindle is remarkably well aligned with the cell longitudinal axis at the onset of mitosis, by growing along the axis of the adjacent interphase MT. Misalignment of nascent spindles can give rise to anucleate cells when spindle elongation is impaired. We propose a new role for interphase microtubules: through interaction with the spindle pole body, interphase microtubules determine the initial alignment of the spindle in the subsequent cell division.
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Affiliation(s)
- Sven K Vogel
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany
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11
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Doxsey S, Zimmerman W, Mikule K. Centrosome control of the cell cycle. Trends Cell Biol 2006; 15:303-11. [PMID: 15953548 DOI: 10.1016/j.tcb.2005.04.008] [Citation(s) in RCA: 242] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2004] [Revised: 04/11/2005] [Accepted: 04/27/2005] [Indexed: 11/25/2022]
Abstract
Early observations of centrosomes, made a century ago, revealed a tiny dark structure surrounded by a radial array of cytoplasmic fibers. We now know that the fibers are microtubules and that the dark organelles are centrosomes that mediate functions far beyond the more conventional role of microtubule organization. More recent evidence demonstrates that the centrosome serves as a scaffold for anchoring an extensive number of regulatory proteins. Among these are cell-cycle regulators whose association with the centrosome is an essential step in cell-cycle control. Such studies show that the centrosome is required for several cell-cycle transitions, including G(1) to S-phase, G(2) to mitosis and metaphase to anaphase. In this review (which is part of the Chromosome Segregation and Aneuploidy series), we discuss recent data that provide the most direct links between centrosomes and cell-cycle progression.
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Affiliation(s)
- Stephen Doxsey
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
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12
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Asakawa K, Kume K, Kanai M, Goshima T, Miyahara K, Dhut S, Tee WW, Hirata D, Toda T. The V260I mutation in fission yeast alpha-tubulin Atb2 affects microtubule dynamics and EB1-Mal3 localization and activates the Bub1 branch of the spindle checkpoint. Mol Biol Cell 2006; 17:1421-35. [PMID: 16394105 PMCID: PMC1382329 DOI: 10.1091/mbc.e05-08-0802] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2005] [Revised: 12/13/2005] [Accepted: 12/27/2005] [Indexed: 11/11/2022] Open
Abstract
We have identified a novel temperature-sensitive mutant of fission yeast alpha-tubulin Atb2 (atb2-983) that contains a single amino acid substitution (V260I). Atb2-983 is incorporated into the microtubules, and their overall structures are not altered noticeably, but microtubule dynamics is compromised during interphase. atb2-983 displays a high rate of chromosome missegregation and is synthetically lethal with deletions in a subset of spindle checkpoint genes including bub1, bub3, and mph1, but not with mad1, mad2, and mad3. During early mitosis in this mutant, Bub1, but not Mad2, remains for a prolonged period in the kinetochores that are situated in proximity to one of the two SPBs (spindle pole bodies). High dosage mal3(+), encoding EB1 homologue, rescues atb2-983, suggesting that Mal3 function is compromised. Consistently, Mal3 localization and binding between Mal3 and Atb2-983 are impaired significantly, and a mal3 single mutant, such as atb2-983, displays prolonged Bub1 kinetochore localization. Furthermore in atb2-983 back-and-forth centromere oscillation during prometaphase is abolished. Intriguingly, this oscillation still occurs in the mal3 mutant, indicating that there is another defect independent of Mal3. These results show that microtubule dynamics is important for coordinated execution of mitotic events, in which Mal3 plays a vital role.
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Affiliation(s)
- Kazuhide Asakawa
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, London WC2A 3PX, UK
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13
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Asakawa K, Toya M, Sato M, Kanai M, Kume K, Goshima T, Garcia MA, Hirata D, Toda T. Mal3, the fission yeast EB1 homologue, cooperates with Bub1 spindle checkpoint to prevent monopolar attachment. EMBO Rep 2006; 6:1194-200. [PMID: 16179942 PMCID: PMC1369205 DOI: 10.1038/sj.embor.7400540] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2005] [Revised: 08/22/2005] [Accepted: 08/24/2005] [Indexed: 11/09/2022] Open
Abstract
Bipolar microtubule attachment is central to genome stability. Here, we investigate the mitotic role of the fission yeast EB1 homologue Mal3. Mal3 shows dynamic inward movement along the spindle, initial emergence at the spindle pole body (SPB) and translocation towards the equatorial plane, followed by sudden disappearance. Deletion of Mal3 results in early mitotic delay, which is dependent on the Bub1, but not the Mad2, spindle checkpoint. Consistently, Bub1, but not Mad2, shows prolonged kinetochore localization. Double mutants between mal3 and a subset of checkpoint mutants, including bub1, bub3, mad3 and mph1, but not mad1 or mad2, show massive chromosome mis-segregation defects. In mal3bub1 mutants, both sister centromeres tend to remain in close proximity to one of the separating SPBs. Further analysis indicates that mis-segregated centromeres are exclusively associated with the mother SPB. Mal3, therefore, has a role in preventing monopolar attachment in cooperation with the Bub1/Bub3/Mad3/Mph1-dependent checkpoint.
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Affiliation(s)
- Kazuhide Asakawa
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
| | - Mika Toya
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
| | - Masamitsu Sato
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
| | - Muneyoshi Kanai
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi Hiroshima 739-8530, Japan
| | - Kazunori Kume
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi Hiroshima 739-8530, Japan
| | - Tetsuya Goshima
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi Hiroshima 739-8530, Japan
| | - Miguel Angel Garcia
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
| | - Dai Hirata
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi Hiroshima 739-8530, Japan
| | - Takashi Toda
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
- Tel: +44 20 7269 3535; Fax: 44 20 7269 3258; E-mail:
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14
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Abstract
Centrosomes, spindle pole bodies, and related structures in other organisms are a morphologically diverse group of organelles that share a common ability to nucleate and organize microtubules and are thus referred to as microtubule organizing centers or MTOCs. Features associated with MTOCs include organization of mitotic spindles, formation of primary cilia, progression through cytokinesis, and self-duplication once per cell cycle. Centrosomes bind more than 100 regulatory proteins, whose identities suggest roles in a multitude of cellular functions. In fact, recent work has shown that MTOCs are required for several regulatory functions including cell cycle transitions, cellular responses to stress, and organization of signal transduction pathways. These new liaisons between MTOCs and cellular regulation are the focus of this review. Elucidation of these and other previously unappreciated centrosome functions promises to yield exciting scientific discovery for some time to come.
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Affiliation(s)
- Stephen Doxsey
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
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15
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Gachet Y, Reyes C, Goldstone S, Tournier S. The fission yeast spindle orientation checkpoint: a model that generates tension? Yeast 2006; 23:1015-29. [PMID: 17072894 DOI: 10.1002/yea.1410] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
In all eukaryotes, the alignment of the mitotic spindle with the axis of cell polarity is essential for accurate chromosome segregation as well as for the establishment of cell fate, and thus morphogenesis, during development. Studies in invertebrates, higher eukaryotes and yeast suggest that astral microtubules interact with the cell cortex to position the spindle. These microtubules are thought to impose pushing or pulling forces on the spindle poles to affect the rotation or movement of the spindle. In the fission yeast model, where cell division is symmetrical, spindle rotation is dependent on the interaction of astral microtubules with the cortical actin cytoskeleton. In these cells, a bub1-dependent mitotic checkpoint, the spindle orientation checkpoint (SOC), is activated when the spindles fail to align with the cell polarity axis. In this paper we review the mechanism that orientates the spindle during mitosis in fission yeast, and discuss the consequences of misorientation on metaphase progression.
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Affiliation(s)
- Yannick Gachet
- LBCMCP-CNRS UMR5088, Institut d'Exploration Fonctionelle des Génomes (IFR109), Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse, France
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16
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Bimbó A, Liu J, Balasubramanian MK. Roles of Pdk1p, a fission yeast protein related to phosphoinositide-dependent protein kinase, in the regulation of mitosis and cytokinesis. Mol Biol Cell 2005; 16:3162-75. [PMID: 15857958 PMCID: PMC1165401 DOI: 10.1091/mbc.e04-09-0769] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Proteins related to the phosphoinositide-dependent protein kinase family have been identified in the majority of eukaryotes. Although much is known about upstream mechanisms that regulate the PDK1-family of kinases in metazoans, how these kinases regulate cell growth and division remains unclear. Here, we characterize a fission yeast protein related to members of this family, which we have termed Pdk1p. Pdk1p localizes to the spindle pole body and the actomyosin ring in early mitotic cells. Cells deleted for pdk1 display multiple defects in mitosis and cytokinesis, all of which are exacerbated when the function of fission yeast polo kinase, Plo1p, is partially compromised. We conclude that Pdk1p functions in concert with Plo1p to regulate multiple processes such as the establishment of a bipolar mitotic spindle, transition to anaphase, placement of the actomyosin ring and proper execution of cytokinesis. We also present evidence that the effects of Pdk1p on cytokinesis are likely mediated via the fission yeast anillin-related protein, Mid1p, and the septation initiation network.
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Affiliation(s)
- Andrea Bimbó
- Cell Division Laboratory, Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Singapore
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17
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Zimmerman S, Daga RR, Chang F. Intra-nuclear microtubules and a mitotic spindle orientation checkpoint. Nat Cell Biol 2005; 6:1245-6. [PMID: 15573098 DOI: 10.1038/ncb1200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2004] [Accepted: 10/19/2004] [Indexed: 11/08/2022]
Abstract
Cells of the fission yeast Schizosaccharomyces pombe have a checkpoint mechanism that reportedly monitors the orientation of the mitotic spindle. Astral microtubules in pre-anaphase spindles are thought to contact the contractile actin ring at the plasma membrane in order to rotate the spindle and to sense spindle orientation. Here, we show that these microtubules are actually inside the nuclear envelope.
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Affiliation(s)
- Sabina Zimmerman
- Department of Microbiology, Columbia University College of Physicians and Surgeons, 701 West 168th Street, New York, NY 10032, USA
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18
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Tolić-Nørrelykke IM, Sacconi L, Thon G, Pavone FS. Positioning and elongation of the fission yeast spindle by microtubule-based pushing. Curr Biol 2004; 14:1181-6. [PMID: 15242615 DOI: 10.1016/j.cub.2004.06.029] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2004] [Revised: 04/29/2004] [Accepted: 05/05/2004] [Indexed: 11/20/2022]
Abstract
In eukaryotic cells, proper position of the mitotic spindle is necessary for successful cell division and development. We explored the nature of forces governing the positioning and elongation of the mitotic spindle in Schizosaccharomyces pombe. We hypothesized that astral microtubules exert mechanical force on the S. pombe spindle and thus help align the spindle with the major axis of the cell. Microtubules were tagged with green fluorescent protein (GFP) and visualized by two-photon microscopy. Forces were inferred both from time-lapse imaging of mitotic cells and, more directly, from mechanical perturbations induced by laser dissection of the spindle and astral microtubules. We found that astral microtubules push on the spindle poles in S. pombe, in contrast to the pulling forces observed in a number of other cell types. Further, laser dissection of the spindle midzone induced spindle collapse inward. This offers direct evidence in support of the hypothesis that spindle elongation is driven by the sliding apart of antiparallel microtubules in the spindle midzone. Broken spindles recovered and mitosis completed as usual. We propose a model of spindle centering and elongation by microtubule-based pushing forces.
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Sawin KE, Lourenco PCC, Snaith HA. Microtubule nucleation at non-spindle pole body microtubule-organizing centers requires fission yeast centrosomin-related protein mod20p. Curr Biol 2004; 14:763-75. [PMID: 15120067 DOI: 10.1016/j.cub.2004.03.042] [Citation(s) in RCA: 155] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2003] [Revised: 03/17/2004] [Accepted: 03/17/2004] [Indexed: 11/18/2022]
Abstract
BACKGROUND Many types of differentiated eukaryotic cells display microtubule distributions consistent with nucleation from noncentrosomal intracellular microtubule organizing centers (MTOCs), although such structures remain poorly characterized. In fission yeast, two types of MTOCs exist in addition to the spindle pole body, the yeast centrosome equivalent. These are the equatorial MTOC, which nucleates microtubules from the cell division site at the end of mitosis, and interphase MTOCs, which nucleate microtubules from multiple sites near the cell nucleus during interphase. RESULTS From an insertional mutagenesis screen we identified a novel gene, mod20+, which is required for microtubule nucleation from non-spindle pole body MTOCs in fission yeast. Mod20p is not required for intranuclear mitotic spindle assembly, although it is required for cytoplasmic astral microtubule growth during mitosis. Mod20p localizes to MTOCs throughout the cell cycle and is also dynamically distributed along microtubules themselves. We find that mod20p is required for the localization of components of the gamma-tubulin complex to non-spindle pole body MTOCs and physically interacts with the gamma-tubulin complex in vivo. Database searches reveal a family of eukaryotic proteins distantly related to mod20p; these are found in organisms ranging from fungi to mammals and include Drosophila centrosomin. CONCLUSIONS Mod20p appears to act by recruiting components of the gamma-tubulin complex to non-spindle pole body MTOCs. The identification of mod20p-related proteins in higher eukaryotes suggests that this may represent a general mechanism for the organization of noncentrosomal MTOCs in eukaryotic cells.
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Affiliation(s)
- Kenneth E Sawin
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, EH9 3JR, United Kingdom.
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Tournier S, Gachet Y, Buck V, Hyams JS, Millar JBA. Disruption of astral microtubule contact with the cell cortex activates a Bub1, Bub3, and Mad3-dependent checkpoint in fission yeast. Mol Biol Cell 2004; 15:3345-56. [PMID: 15146064 PMCID: PMC452588 DOI: 10.1091/mbc.e04-03-0256] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
In animal and yeast cells, the mitotic spindle is aligned perpendicularly to the axis of cell division. This ensures that sister chromatids are separated to opposite sides of the cytokinetic actomyosin ring. In fission yeast, spindle rotation is dependent upon the interaction of astral microtubules with the cortical actin cytoskeleton. In this article, we show that addition of Latrunculin A, which prevents spindle rotation, delays the separation of sister chromatids and anaphase promoting complex-mediated destruction of spindle-associated Securin and Cyclin B. Moreover, we find that whereas sister kinetochore pairs normally congress to the spindle midzone before anaphase onset, this congression is disrupted when astral microtubule contact with the actin cytoskeleton is disturbed. By analyzing the timing of kinetochore separation, we find that this anaphase delay requires the Bub3, Mad3, and Bub1 but not the Mad1 or Mad2 spindle assembly checkpoint proteins. In agreement with this, we find that Bub1 remains associated with kinetochores when spindles are mispositioned. These data indicate that, in fission yeast, astral microtubule contact with the medial cell cortex is monitored by a subset of spindle assembly checkpoint proteins. We propose that this checkpoint ensures spindles are properly oriented before anaphase takes place.
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Affiliation(s)
- Sylvie Tournier
- Division of Yeast Genetics, National Institute for Medical Research, London NW7 1AA, United Kingdom
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Zimmerman WC, Sillibourne J, Rosa J, Doxsey SJ. Mitosis-specific anchoring of gamma tubulin complexes by pericentrin controls spindle organization and mitotic entry. Mol Biol Cell 2004; 15:3642-57. [PMID: 15146056 PMCID: PMC491825 DOI: 10.1091/mbc.e03-11-0796] [Citation(s) in RCA: 227] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Microtubule nucleation is the best known function of centrosomes. Centrosomal microtubule nucleation is mediated primarily by gamma tubulin ring complexes (gamma TuRCs). However, little is known about the molecules that anchor these complexes to centrosomes. In this study, we show that the centrosomal coiled-coil protein pericentrin anchors gamma TuRCs at spindle poles through an interaction with gamma tubulin complex proteins 2 and 3 (GCP2/3). Pericentrin silencing by small interfering RNAs in somatic cells disrupted gamma tubulin localization and spindle organization in mitosis but had no effect on gamma tubulin localization or microtubule organization in interphase cells. Similarly, overexpression of the GCP2/3 binding domain of pericentrin disrupted the endogenous pericentrin-gamma TuRC interaction and perturbed astral microtubules and spindle bipolarity. When added to Xenopus mitotic extracts, this domain uncoupled gamma TuRCs from centrosomes, inhibited microtubule aster assembly, and induced rapid disassembly of preassembled asters. All phenotypes were significantly reduced in a pericentrin mutant with diminished GCP2/3 binding and were specific for mitotic centrosomal asters as we observed little effect on interphase asters or on asters assembled by the Ran-mediated centrosome-independent pathway. Additionally, pericentrin silencing or overexpression induced G2/antephase arrest followed by apoptosis in many but not all cell types. We conclude that pericentrin anchoring of gamma tubulin complexes at centrosomes in mitotic cells is required for proper spindle organization and that loss of this anchoring mechanism elicits a checkpoint response that prevents mitotic entry and triggers apoptotic cell death.
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Affiliation(s)
- Wendy C Zimmerman
- Department of Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
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