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Conway W, Kiewisz R, Fabig G, Kelleher CP, Wu HY, Anjur-Dietrich M, Müller-Reichert T, Needleman DJ. Self-organization of kinetochore-fibers in human mitotic spindles. eLife 2022; 11:75458. [PMID: 35876665 PMCID: PMC9398449 DOI: 10.7554/elife.75458] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 07/24/2022] [Indexed: 11/22/2022] Open
Abstract
During eukaryotic cell division, chromosomes are linked to microtubules (MTs) in the spindle by a macromolecular complex called the kinetochore. The bound kinetochore microtubules (KMTs) are crucial to ensuring accurate chromosome segregation. Recent reconstructions by electron tomography (Kiewisz et al., 2022) captured the positions and configurations of every MT in human mitotic spindles, revealing that roughly half the KMTs in these spindles do not reach the pole. Here, we investigate the processes that give rise to this distribution of KMTs using a combination of analysis of large-scale electron tomography, photoconversion experiments, quantitative polarized light microscopy, and biophysical modeling. Our results indicate that in metaphase, KMTs grow away from the kinetochores along well-defined trajectories, with the speed of the KMT minus ends continually decreasing as the minus ends approach the pole, implying that longer KMTs grow more slowly than shorter KMTs. The locations of KMT minus ends, and the turnover and movements of tubulin in KMTs, are consistent with models in which KMTs predominately nucleate de novo at kinetochores in metaphase and are inconsistent with substantial numbers of non-KMTs being recruited to the kinetochore in metaphase. Taken together, this work leads to a mathematical model of the self-organization of kinetochore-fibers in human mitotic spindles.
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Affiliation(s)
- William Conway
- Department of Physics, Harvard University, Cambridge, United States
| | - Robert Kiewisz
- Experimental Center, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Gunar Fabig
- Experimental Center, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Colm P Kelleher
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
| | - Hai-Yin Wu
- Department of Physics, Harvard University, Cambridge, United States
| | - Maya Anjur-Dietrich
- John A Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, United States
| | - Thomas Müller-Reichert
- Experimental Center, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Daniel J Needleman
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
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2
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Schrock MS, Scarberry L, Stromberg BR, Sears C, Torres AE, Tallman D, Krupinski L, Chakravarti A, Summers MK. MKLP2 functions in early mitosis to ensure proper chromosome congression. J Cell Sci 2022; 135:275559. [PMID: 35638575 DOI: 10.1242/jcs.259560] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 05/23/2022] [Indexed: 11/20/2022] Open
Abstract
Mitotic kinesin-like protein 2 (MKLP2) is a motor protein with a well-established function in promoting cytokinesis. However, our results with siRNAs targeting MKLP2 and small molecule inhibitors of MKLP2 (MKLP2i) suggested a function earlier in mitosis, prior to anaphase. In this study we provide direct evidence that MKLP2 facilitates chromosome congression in prometaphase. We employed live imaging to observe HeLa cells with fluorescently tagged histones treated with MKLP2i and discovered a pronounced chromosome congression defect. We show that MKLP2 facilitates error correction as inhibited cells had a significant increase in unstable, syntelic kinetochore-microtubule attachments. We find that the aberrant attachments are accompanied by elevated Aurora Kinase (A/B) activity and phosphorylation of the downstream target, pHEC1 (Ser 55). Lastly, we show that MKLP2 inhibition results in aneuploidy, confirming that MKLP2 safeguards cells against chromosomal instability.
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Affiliation(s)
- Morgan S Schrock
- Department of Radiation Oncology, Arthur G James Comprehensive Cancer Center and Richard L. Solove Research Institute, The Ohio State University, Columbus, OH, 43210, USA
| | - Luke Scarberry
- Department of Radiation Oncology, Arthur G James Comprehensive Cancer Center and Richard L. Solove Research Institute, The Ohio State University, Columbus, OH, 43210, USA.,Biomedical Sciences Graduate, Program The Ohio State University Columbus, OH, 43210, USA
| | - Benjamin R Stromberg
- Department of Radiation Oncology, Arthur G James Comprehensive Cancer Center and Richard L. Solove Research Institute, The Ohio State University, Columbus, OH, 43210, USA.,Biomedical Sciences Graduate, Program The Ohio State University Columbus, OH, 43210, USA
| | - Claire Sears
- Department of Radiation Oncology, Arthur G James Comprehensive Cancer Center and Richard L. Solove Research Institute, The Ohio State University, Columbus, OH, 43210, USA.,Undergraduate Studies, Kenyon College, Gambier, OH, 43022, USA
| | - Adrian E Torres
- Department of Radiation Oncology, Arthur G James Comprehensive Cancer Center and Richard L. Solove Research Institute, The Ohio State University, Columbus, OH, 43210, USA
| | - David Tallman
- Department of Internal Medicine, The Ohio State University, Columbus, OH, 43210, USA.,Molecular, Cellular, and Developmental Biology Graduate Program, The Ohio State University, Columbus, OH, 43210, USA
| | - Lucas Krupinski
- Department of Radiation Oncology, Arthur G James Comprehensive Cancer Center and Richard L. Solove Research Institute, The Ohio State University, Columbus, OH, 43210, USA
| | - Arnab Chakravarti
- Department of Radiation Oncology, Arthur G James Comprehensive Cancer Center and Richard L. Solove Research Institute, The Ohio State University, Columbus, OH, 43210, USA
| | - Matthew K Summers
- Department of Radiation Oncology, Arthur G James Comprehensive Cancer Center and Richard L. Solove Research Institute, The Ohio State University, Columbus, OH, 43210, USA
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3
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Kumari A, Kumar C, Pergu R, Kumar M, Mahale SP, Wasnik N, Mylavarapu SVS. Phosphorylation and Pin1 binding to the LIC1 subunit selectively regulate mitotic dynein functions. J Cell Biol 2021; 220:212736. [PMID: 34709360 PMCID: PMC8562849 DOI: 10.1083/jcb.202005184] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 05/13/2021] [Accepted: 09/22/2021] [Indexed: 01/31/2023] Open
Abstract
The dynein motor performs multiple functions in mitosis by engaging with a wide cargo spectrum. One way to regulate dynein's cargo-binding selectivity is through the C-terminal domain (CTD) of its light intermediate chain 1 subunit (LIC1), which binds directly with cargo adaptors. Here we show that mitotic phosphorylation of LIC1-CTD at its three cdk1 sites is required for proper mitotic progression, for dynein loading onto prometaphase kinetochores, and for spindle assembly checkpoint inactivation in human cells. Mitotic LIC1-CTD phosphorylation also engages the prolyl isomerase Pin1 predominantly to Hook2-dynein-Nde1-Lis1 complexes, but not to dynein-spindly-dynactin complexes. LIC1-CTD dephosphorylation abrogates dynein-Pin1 binding, promotes prophase centrosome-nuclear envelope detachment, and impairs metaphase chromosome congression and mitotic Golgi fragmentation, without affecting interphase membrane transport. Phosphomutation of a conserved LIC1-CTD SP site in zebrafish leads to early developmental defects. Our work reveals that LIC1-CTD phosphorylation differentially regulates distinct mitotic dynein pools and suggests the evolutionary conservation of this phosphoregulation.
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Affiliation(s)
- Amrita Kumari
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, third Milestone Faridabad-Gurgaon Expressway, Faridabad Haryana, India.,Manipal Academy of Higher Education, Manipal Karnataka, India
| | - Chandan Kumar
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, third Milestone Faridabad-Gurgaon Expressway, Faridabad Haryana, India
| | - Rajaiah Pergu
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, third Milestone Faridabad-Gurgaon Expressway, Faridabad Haryana, India.,Manipal Academy of Higher Education, Manipal Karnataka, India
| | - Megha Kumar
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, third Milestone Faridabad-Gurgaon Expressway, Faridabad Haryana, India.,Council of Scientific and Industrial Research, Centre for Cellular and Molecular Biology, Habsiguda, Hyderabad, Telangana, India.,Academy of Scientific and Innovative Research, New Delhi, India
| | - Sagar P Mahale
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, third Milestone Faridabad-Gurgaon Expressway, Faridabad Haryana, India.,Manipal Academy of Higher Education, Manipal Karnataka, India
| | - Neeraj Wasnik
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, third Milestone Faridabad-Gurgaon Expressway, Faridabad Haryana, India
| | - Sivaram V S Mylavarapu
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, third Milestone Faridabad-Gurgaon Expressway, Faridabad Haryana, India.,Manipal Academy of Higher Education, Manipal Karnataka, India
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4
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Ferreira LT, Maiato H. Prometaphase. Semin Cell Dev Biol 2021; 117:52-61. [PMID: 34127384 DOI: 10.1016/j.semcdb.2021.06.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/31/2021] [Accepted: 06/02/2021] [Indexed: 11/28/2022]
Abstract
The establishment of a metaphase plate in which all chromosomes are attached to mitotic spindle microtubules and aligned at the cell equator is required for faithful chromosome segregation in metazoans. The achievement of this configuration relies on the precise coordination between several concurrent mechanisms that start upon nuclear envelope breakdown, mediate chromosome capture at their kinetochores during mitotic spindle assembly and culminate with the congression of all chromosomes to the spindle equator. This period is called 'prometaphase'. Because the nature of chromosome capture by mitotic spindle microtubules is error prone, the cell is provided of error correction mechanisms that sense and correct most erroneous kinetochore-microtubule attachments before committing to separate sister chromatids in anaphase. In this review, aimed for newcomers in the field, more than providing an exhaustive mechanistic coverage of each and every concurrent mechanism taking place during prometaphase, we provide an integrative overview of these processes that ultimately promote the subsequent faithful segregation of chromosomes during mitosis.
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Affiliation(s)
- Luísa T Ferreira
- Chromosome Instability & Dynamics Group, i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
| | - Helder Maiato
- Chromosome Instability & Dynamics Group, i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; Cell Division Group, Experimental Biology Unit, Department of Biomedicine, Faculdade de Medicina, Universidade do Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto, Portugal.
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5
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BUBR1 Pseudokinase Domain Promotes Kinetochore PP2A-B56 Recruitment, Spindle Checkpoint Silencing, and Chromosome Alignment. Cell Rep 2020; 33:108397. [PMID: 33207204 DOI: 10.1016/j.celrep.2020.108397] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 10/13/2020] [Accepted: 10/26/2020] [Indexed: 12/13/2022] Open
Abstract
The balance of phospho-signaling at the outer kinetochore is critical for forming accurate attachments between kinetochores and the mitotic spindle and timely exit from mitosis. A major player in determining this balance is the PP2A-B56 phosphatase, which is recruited to the kinase attachment regulatory domain (KARD) of budding uninhibited by benzimidazole 1-related 1 (BUBR1) in a phospho-dependent manner. This unleashes a rapid, switch-like phosphatase relay that reverses mitotic phosphorylation at the kinetochore, extinguishing the checkpoint and promoting anaphase. Here, we demonstrate that the C-terminal pseudokinase domain of human BUBR1 is required to promote KARD phosphorylation. Mutation or removal of the pseudokinase domain results in decreased PP2A-B56 recruitment to the outer kinetochore attenuated checkpoint silencing and errors in chromosome alignment as a result of imbalance in Aurora B activity. Our data, therefore, elucidate a function for the BUBR1 pseudokinase domain in ensuring accurate and timely exit from mitosis.
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6
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Dudka D, Noatynska A, Smith CA, Liaudet N, McAinsh AD, Meraldi P. Complete microtubule-kinetochore occupancy favours the segregation of merotelic attachments. Nat Commun 2018; 9:2042. [PMID: 29795284 PMCID: PMC5966435 DOI: 10.1038/s41467-018-04427-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 04/30/2018] [Indexed: 12/03/2022] Open
Abstract
Kinetochores are multi-protein complexes that power chromosome movements by tracking microtubules plus-ends in the mitotic spindle. Human kinetochores bind up to 20 microtubules, even though single microtubules can generate sufficient force to move chromosomes. Here, we show that high microtubule occupancy at kinetochores ensures robust chromosome segregation by providing a strong mechanical force that favours segregation of merotelic attachments during anaphase. Using low doses of the microtubules-targeting agent BAL27862 we reduce microtubule occupancy and observe that spindle morphology is unaffected and bi-oriented kinetochores can still oscillate with normal intra-kinetochore distances. Inter-kinetochore stretching is, however, dramatically reduced. The reduction in microtubule occupancy and inter-kinetochore stretching does not delay satisfaction of the spindle assembly checkpoint or induce microtubule detachment via Aurora-B kinase, which was so far thought to release microtubules from kinetochores under low stretching. Rather, partial microtubule occupancy slows down anaphase A and increases incidences of lagging chromosomes due to merotelically attached kinetochores. Single microtubules (MTs) can move chromosomes, but it is unclear why kinetochores bind up to 20 MTs. Here, the authors decrease the number of kinetochore MTs with BAL27862 and see lagging chromosomes, suggesting that numerous kinetochore MTs provide force ensuring robust chromosomal segregation.
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Affiliation(s)
- Damian Dudka
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, 1211, Geneva 4, Switzerland
| | - Anna Noatynska
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, 1211, Geneva 4, Switzerland
| | - Chris A Smith
- Centre for Mechanochemical Cell Biology & Division of Biomedical Sciences, Warwick Medical School, University of Warwick, CV4 7AL, Coventry, UK.,Metabolic Research Laboratories and MRC Metabolic Diseases Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
| | - Nicolas Liaudet
- Bioimaging Facility, Faculty of Medicine, University of Geneva, 1211, Geneva 4, Switzerland
| | - Andrew D McAinsh
- Centre for Mechanochemical Cell Biology & Division of Biomedical Sciences, Warwick Medical School, University of Warwick, CV4 7AL, Coventry, UK
| | - Patrick Meraldi
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, 1211, Geneva 4, Switzerland. .,Translational Research Centre in Onco-hematology, Faculty of Medicine, University of Geneva, 1211, Geneva 4, Switzerland.
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