1
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Virant D, Vojnovic I, Winkelmeier J, Endesfelder M, Turkowyd B, Lando D, Endesfelder U. Unraveling the kinetochore nanostructure in Schizosaccharomyces pombe using multi-color SMLM imaging. J Cell Biol 2023; 222:213836. [PMID: 36705602 PMCID: PMC9930162 DOI: 10.1083/jcb.202209096] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Revised: 12/20/2022] [Accepted: 12/27/2022] [Indexed: 01/28/2023] Open
Abstract
The key to ensuring proper chromosome segregation during mitosis is the kinetochore (KT), a tightly regulated multiprotein complex that links the centromeric chromatin to the spindle microtubules and as such leads the segregation process. Understanding its architecture, function, and regulation is therefore essential. However, due to its complexity and dynamics, only its individual subcomplexes could be studied in structural detail so far. In this study, we construct a nanometer-precise in situ map of the human-like regional KT of Schizosaccharomyces pombe using multi-color single-molecule localization microscopy. We measure each protein of interest (POI) in conjunction with two references, cnp1CENP-A at the centromere and sad1 at the spindle pole. This allows us to determine cell cycle and mitotic plane, and to visualize individual centromere regions separately. We determine protein distances within the complex using Bayesian inference, establish the stoichiometry of each POI and, consequently, build an in situ KT model with unprecedented precision, providing new insights into the architecture.
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Affiliation(s)
- David Virant
- https://ror.org/05r7n9c40Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiologyand LOEWE Center for Synthetic Microbiology, Marburg, Germany
| | - Ilijana Vojnovic
- https://ror.org/05r7n9c40Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiologyand LOEWE Center for Synthetic Microbiology, Marburg, Germany,Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA,Institute for Microbiology and Biotechnology, Rheinische-Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Jannik Winkelmeier
- https://ror.org/05r7n9c40Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiologyand LOEWE Center for Synthetic Microbiology, Marburg, Germany,Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA,Institute for Microbiology and Biotechnology, Rheinische-Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Marc Endesfelder
- https://ror.org/05591te55Institute for Assyriology and Hittitology, Ludwig-Maximilians-Universität München, München, Germany
| | - Bartosz Turkowyd
- https://ror.org/05r7n9c40Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiologyand LOEWE Center for Synthetic Microbiology, Marburg, Germany,Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA,Institute for Microbiology and Biotechnology, Rheinische-Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - David Lando
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Ulrike Endesfelder
- https://ror.org/05r7n9c40Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiologyand LOEWE Center for Synthetic Microbiology, Marburg, Germany,Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA,Institute for Microbiology and Biotechnology, Rheinische-Friedrich-Wilhelms-Universität Bonn, Bonn, Germany,Correspondence to Ulrike Endesfelder:
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2
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Embacher PA, Germanova TE, Roscioli E, McAinsh AD, Burroughs NJ. Bayesian inference of multi-point macromolecular architecture mixtures at nanometre resolution. PLoS Comput Biol 2022; 18:e1010765. [PMID: 36574448 PMCID: PMC9829179 DOI: 10.1371/journal.pcbi.1010765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 01/09/2023] [Accepted: 11/28/2022] [Indexed: 12/29/2022] Open
Abstract
Gaussian spot fitting methods have significantly extended the spatial range where fluorescent microscopy can be used, with recent techniques approaching nanometre (nm) resolutions. However, small inter-fluorophore distances are systematically over-estimated for typical molecular scales. This bias can be corrected computationally, but current algorithms are limited to correcting distances between pairs of fluorophores. Here we present a flexible Bayesian computational approach that infers the distances and angles between multiple fluorophores and has several advantages over these previous methods. Specifically it improves confidence intervals for small lengths, estimates measurement errors of each fluorophore individually and infers the correlations between polygon lengths. The latter is essential for determining the full multi-fluorophore 3D architecture. We further developed the algorithm to infer the mixture composition of a heterogeneous population of multiple polygon states. We use our algorithm to analyse the 3D architecture of the human kinetochore, a macro-molecular complex that is essential for high fidelity chromosome segregation during cell division. Using triple fluorophore image data we unravel the mixture of kinetochore states during human mitosis, inferring the conformation of microtubule attached and unattached kinetochores and their proportions across mitosis. We demonstrate that the attachment conformation correlates with intersister tension and sister alignment to the metaphase plate.
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Affiliation(s)
- Peter A. Embacher
- Department of Medical Physics & Biomedical Engineering, University College London, London, United Kingdom
| | - Tsvetelina E. Germanova
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom
| | - Emanuele Roscioli
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom
| | - Andrew D. McAinsh
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom
| | - Nigel J. Burroughs
- Mathematics Institute and Zeeman Institute, University of Warwick, Coventry, United Kingdom
- * E-mail:
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3
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de Regt AK, Clark CJ, Asbury CL, Biggins S. Tension can directly suppress Aurora B kinase-triggered release of kinetochore-microtubule attachments. Nat Commun 2022; 13:2152. [PMID: 35443757 PMCID: PMC9021268 DOI: 10.1038/s41467-022-29542-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 03/03/2022] [Indexed: 11/09/2022] Open
Abstract
Chromosome segregation requires sister kinetochores to attach microtubules emanating from opposite spindle poles. Proper attachments come under tension and are stabilized, but defective attachments lacking tension are released, giving another chance for correct attachments to form. This error correction process depends on Aurora B kinase, which phosphorylates kinetochores to destabilize their microtubule attachments. However, the mechanism by which Aurora B distinguishes tense versus relaxed kinetochores remains unclear because it is difficult to detect kinase-triggered detachment and to manipulate kinetochore tension in vivo. To address these challenges, we apply an optical trapping-based assay using soluble Aurora B and reconstituted kinetochore-microtubule attachments. Strikingly, the tension on these attachments suppresses their Aurora B-triggered release, suggesting that tension-dependent changes in the conformation of kinetochores can regulate Aurora B activity or its outcome. Our work uncovers the basis for a key mechano-regulatory event that ensures accurate segregation and may inform studies of other mechanically regulated enzymes.
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Affiliation(s)
- Anna K de Regt
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Cordell J Clark
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Charles L Asbury
- Department of Physiology and Biophysics, University of Washington, Seattle, WA, USA.
| | - Sue Biggins
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA.
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4
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Martin IM, Aponte-Santamaría C, Schmidt L, Hedtfeld M, Iusupov A, Musacchio A, Gräter F. Phosphorylation tunes elongation propensity and cohesiveness of INCENP's intrinsically disordered region. J Mol Biol 2021; 434:167387. [PMID: 34883116 DOI: 10.1016/j.jmb.2021.167387] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 11/24/2021] [Accepted: 11/30/2021] [Indexed: 11/16/2022]
Abstract
The inner centromere protein, INCENP, is crucial for correct chromosome segregation during mitosis. It connects the kinase Aurora B to the inner centromere allowing this kinase to dynamically access its kinetochore targets. However, the function of its central, 440-residue long intrinsically disordered region (IDR) and its multiple phosphorylation sites is unclear. Here, we determined the conformational ensemble of INCENP's IDR, systematically varying the level of phosphorylation, using all-atom and coarse-grain molecular dynamics simulations. Our simulations show that phosphorylation expands INCENP's IDR, both locally and globally, mainly by increasing its overall net charge. The disordered region undergoes critical globule-to-coil conformational transitions and the transition temperature non-monotonically depends on the degree of phosphorylation, with a mildly phosphorylated case of neutral net charge featuring the highest collapse propensity. The IDR transitions from a multitude of globular states, accompanied by several specific internal contacts that reduce INCENP length by loop formation, to weakly interacting and highly extended coiled conformations. Phosphorylation critically shifts the population between these two regimes. It thereby influences cohesiveness and phase behavior of INCENP IDR assemblies, a feature presumably relevant for INCENP's function in the chromosomal passenger complex. Overall, we propose the disordered region of INCENP to act as a phosphorylation-regulated and length-variable component, within the previously defined "dog-leash" model, that thereby regulates how Aurora B reaches its targets for proper chromosome segregation.
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Affiliation(s)
- Isabel M Martin
- Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany. https://twitter.com/@IsabelMMartin
| | - Camilo Aponte-Santamaría
- Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany; Max Planck Tandem Group in Computational Biophysics, University of Los Andes, Cra. 1 #18a-12, 111711 Bogotá, Colombia. https://twitter.com/@camiloapontelab
| | - Lisa Schmidt
- Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany
| | - Marius Hedtfeld
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany; International Max Planck Research School for Living Matter, Otto-Hahn-Straße 11, 44227 Dortmund, Germany; Centre for Medical Biotechnology, Faculty of Biology, University Duisburg-Essen, Essen, Germany
| | - Adel Iusupov
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany; University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany; Max Planck School Matter to Life, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - Andrea Musacchio
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany; Centre for Medical Biotechnology, Faculty of Biology, University Duisburg-Essen, Essen, Germany. https://twitter.com/@AndreaMusacchi1
| | - Frauke Gräter
- Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany; Max Planck School Matter to Life, Jahnstrasse 29, 69120 Heidelberg, Germany; Interdisciplinary Center for Scientific Computing, Heidelberg University, INF 205, 69120 Heidelberg, Germany.
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5
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Brusini L, D'Archivio S, McDonald J, Wickstead B. Trypanosome KKIP1 Dynamically Links the Inner Kinetochore to a Kinetoplastid Outer Kinetochore Complex. Front Cell Infect Microbiol 2021; 11:641174. [PMID: 33834005 PMCID: PMC8023272 DOI: 10.3389/fcimb.2021.641174] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Accepted: 02/16/2021] [Indexed: 02/02/2023] Open
Abstract
Kinetochores perform an essential role in eukaryotes, coupling chromosomes to the mitotic spindle. In model organisms they are composed of a centromere-proximal inner kinetochore and an outer kinetochore network that binds to microtubules. In spite of universal function, the composition of kinetochores in extant eukaryotes differs greatly. In trypanosomes and other Kinetoplastida, kinetochores are extremely divergent, with most components showing no detectable similarity to proteins in other systems. They may also be very different functionally, potentially binding to the spindle directly via an inner-kinetochore protein. However, we do not know the extent of the trypanosome kinetochore, and proteins interacting with a highly divergent Ndc80/Nuf2-like protein (KKIP1) suggest the existence of more centromere-distal complexes. Here we use quantitative proteomics from multiple start-points to define a stable 9-protein kinetoplastid outer kinetochore (KOK) complex. This complex incorporates proteins recruited from other nuclear processes, exemplifying the role of moonlighting proteins in kinetochore evolution. The outer kinetochore complex is physically distinct from inner-kinetochore proteins, but nanometer-scale label separation shows that KKIP1 bridges the two plates in the same orientation as Ndc80. Moreover, KKIP1 exhibits substantial elongation at metaphase, altering kinetochore structure in a manner consistent with pulling at the outer plate. Together, these data suggest that the KKIP1/KOK likely constitute the extent of the trypanosome outer kinetochore and that this assembly binds to the spindle with sufficient strength to stretch the kinetochore, showing design parallels may exist in organisms with very different kinetochore composition.
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Affiliation(s)
- Lorenzo Brusini
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom.,Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| | - Simon D'Archivio
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom.,Sygnature Discovery, Nottingham, United Kingdom
| | - Jennifer McDonald
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom.,Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Bill Wickstead
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
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6
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Kukreja AA, Kavuri S, Joglekar AP. Microtubule Attachment and Centromeric Tension Shape the Protein Architecture of the Human Kinetochore. Curr Biol 2020; 30:4869-4881.e5. [PMID: 33035484 DOI: 10.1016/j.cub.2020.09.038] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 07/23/2020] [Accepted: 09/14/2020] [Indexed: 12/18/2022]
Abstract
The nanoscale protein architecture of the kinetochore plays an integral role in specifying the mechanisms underlying its functions in chromosome segregation. However, defining this architecture in human cells remains challenging because of the large size and compositional complexity of the kinetochore. Here, we use Förster resonance energy transfer to reveal the architecture of individual kinetochore-microtubule attachments in human cells. We find that the microtubule-binding domains of the Ndc80 complex cluster at the microtubule plus end. This clustering occurs only after microtubule attachment, and it increases proportionally with centromeric tension. Surprisingly, Ndc80 complex clustering is independent of the organization and number of its centromeric receptors. Moreover, this clustering is similar in yeast and human kinetochores despite significant differences in their centromeric organizations. These and other data suggest that the microtubule-binding interface of the human kinetochore behaves like a flexible "lawn" despite being nucleated by repeating biochemical subunits.
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Affiliation(s)
- Alexander A Kukreja
- Department of Biophysics, University of Michigan, 930 N. University Avenue, Ann Arbor, MI 48109, USA
| | - Sisira Kavuri
- Department of Cellular & Developmental Biology, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA
| | - Ajit P Joglekar
- Department of Biophysics, University of Michigan, 930 N. University Avenue, Ann Arbor, MI 48109, USA; Department of Cellular & Developmental Biology, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA.
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7
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Pandey N, Keifenheim D, Yoshida MM, Hassebroek VA, Soroka C, Azuma Y, Clarke DJ. Topoisomerase II SUMOylation activates a metaphase checkpoint via Haspin and Aurora B kinases. J Cell Biol 2020; 219:jcb.201807189. [PMID: 31712254 PMCID: PMC7039214 DOI: 10.1083/jcb.201807189] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 07/17/2019] [Accepted: 10/03/2019] [Indexed: 12/17/2022] Open
Abstract
To prevent chromosome missegregation, a metaphase checkpoint is activated when topoisomerase II is catalytically inhibited and DNA catenations persist. Pandey et al. dissect the key molecular events triggering this regulatory system. Topoisomerase II (Topo II) is essential for mitosis since it resolves sister chromatid catenations. Topo II dysfunction promotes aneuploidy and drives cancer. To protect from aneuploidy, cells possess mechanisms to delay anaphase onset when Topo II is perturbed, providing additional time for decatenation. Molecular insight into this checkpoint is lacking. Here we present evidence that catalytic inhibition of Topo II, which activates the checkpoint, leads to SUMOylation of the Topo II C-terminal domain (CTD). This modification triggers mobilization of Aurora B kinase from inner centromeres to kinetochore proximal centromeres and the core of chromosome arms. Aurora B recruitment accompanies histone H3 threonine-3 phosphorylation and requires Haspin kinase. Strikingly, activation of the checkpoint depends both on Haspin and Aurora B. Moreover, mutation of the conserved CTD SUMOylation sites perturbs Aurora B recruitment and checkpoint activation. The data indicate that SUMOylated Topo II recruits Aurora B to ectopic sites, constituting the molecular trigger of the metaphase checkpoint when Topo II is catalytically inhibited.
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Affiliation(s)
- Nootan Pandey
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS
| | - Daniel Keifenheim
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN
| | | | | | - Caitlin Soroka
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS
| | - Yoshiaki Azuma
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS
| | - Duncan J Clarke
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN
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8
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Renda F, Magidson V, Tikhonenko I, Fisher R, Miles C, Mogilner A, Khodjakov A. Effects of malleable kinetochore morphology on measurements of intrakinetochore tension. Open Biol 2020; 10:200101. [PMID: 32634373 PMCID: PMC7571466 DOI: 10.1098/rsob.200101] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The distance between fluorescent spots formed by various kinetochore proteins (delta) is commonly interpreted as a manifestation of intrakinetochore tension (IKT) caused by microtubule-mediated forces. However, large-scale changes of the kinetochore architecture (such as its shape or dimensions) may also contribute to the value of delta. To assess contributions of these non-elastic changes, we compare behaviour of delta values in human kinetochores with small yet mechanically malleable kinetochores against compound kinetochores in Indian muntjac (IM) cells whose architecture remains constant. Due to the micrometre-scale length of kinetochore plates in IM, their shape and orientation are discernible in conventional light microscopy, which enables precise measurements of IKT independent of contributions from changes in overall architecture of the organelle. We find that delta in IM kinetochores remains relatively constant when microtubule-mediated forces are suppressed by Taxol, but it prominently decreases upon detachment of microtubules. By contrast, large decreases of delta observed in Taxol-treated human cells coincide with prominent changes in length and curvature of the kinetochore plate. These observations, supported by computational modelling, suggest that at least 50% of the decrease in delta in human cells reflects malleable reorganization of kinetochore architecture rather than elastic recoil due to IKT.
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Affiliation(s)
- Fioranna Renda
- New York State Department of Health, Wadsworth Center, Albany, NY, USA
| | - Valentin Magidson
- New York State Department of Health, Wadsworth Center, Albany, NY, USA
| | - Irina Tikhonenko
- New York State Department of Health, Wadsworth Center, Albany, NY, USA
| | - Rebecca Fisher
- New York State Department of Health, Wadsworth Center, Albany, NY, USA
| | - Christopher Miles
- Courant Institute and Department of Biology, New York University, New York, NY, USA
| | - Alex Mogilner
- Courant Institute and Department of Biology, New York University, New York, NY, USA
| | - Alexey Khodjakov
- New York State Department of Health, Wadsworth Center, Albany, NY, USA.,Rensselaer Polytechnic Institute, Troy, NY, USA
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9
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Roscioli E, Germanova TE, Smith CA, Embacher PA, Erent M, Thompson AI, Burroughs NJ, McAinsh AD. Ensemble-Level Organization of Human Kinetochores and Evidence for Distinct Tension and Attachment Sensors. Cell Rep 2020; 31:107535. [PMID: 32348762 PMCID: PMC7196887 DOI: 10.1016/j.celrep.2020.107535] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 02/10/2020] [Accepted: 03/27/2020] [Indexed: 12/13/2022] Open
Abstract
Kinetochores are multi-protein machines that form dynamic attachments to microtubules and control chromosome segregation. High fidelity is ensured because kinetochores can monitor attachment status and tension, using this information to activate checkpoints and error-correction mechanisms. To explore how kinetochores achieve this, we used two- and three-color subpixel fluorescence localization to define how proteins from six major complexes (CCAN, MIS12, NDC80, KNL1, RZZ, and SKA) and the checkpoint proteins Bub1, Mad1, and Mad2 are organized in the human kinetochore. This reveals how the outer kinetochore has a high nematic order and is largely invariant to the loss of attachment or tension, except for two mechanical sensors. First, Knl1 unravels to relay tension, and second, NDC80 undergoes jackknifing and loss of nematic order under microtubule detachment, with only the latter wired up to the checkpoint signaling system. This provides insight into how kinetochores integrate mechanical signals to promote error-free chromosome segregation.
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Affiliation(s)
- Emanuele Roscioli
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, UK; Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK
| | - Tsvetelina E Germanova
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, UK; Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK
| | - Christopher A Smith
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, UK; Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK
| | - Peter A Embacher
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, UK; Mathematics Institute, University of Warwick, Coventry, UK
| | - Muriel Erent
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, UK; Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK
| | - Amelia I Thompson
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, UK; Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK
| | - Nigel J Burroughs
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, UK; Mathematics Institute, University of Warwick, Coventry, UK.
| | - Andrew D McAinsh
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, UK; Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK.
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10
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Edelmaier C, Lamson AR, Gergely ZR, Ansari S, Blackwell R, McIntosh JR, Glaser MA, Betterton MD. Mechanisms of chromosome biorientation and bipolar spindle assembly analyzed by computational modeling. eLife 2020; 9:48787. [PMID: 32053104 PMCID: PMC7311174 DOI: 10.7554/elife.48787] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 02/12/2020] [Indexed: 01/19/2023] Open
Abstract
The essential functions required for mitotic spindle assembly and chromosome biorientation and segregation are not fully understood, despite extensive study. To illuminate the combinations of ingredients most important to align and segregate chromosomes and simultaneously assemble a bipolar spindle, we developed a computational model of fission-yeast mitosis. Robust chromosome biorientation requires progressive restriction of attachment geometry, destabilization of misaligned attachments, and attachment force dependence. Large spindle length fluctuations can occur when the kinetochore-microtubule attachment lifetime is long. The primary spindle force generators are kinesin-5 motors and crosslinkers in early mitosis, while interkinetochore stretch becomes important after biorientation. The same mechanisms that contribute to persistent biorientation lead to segregation of chromosomes to the poles after anaphase onset. This model therefore provides a framework to interrogate key requirements for robust chromosome biorientation, spindle length regulation, and force generation in the spindle. Before a cell divides, it must make a copy of its genetic material and then promptly split in two. This process, called mitosis, is coordinated by many different molecular machines. The DNA is copied, then the duplicated chromosomes line up at the middle of the cell. Next, an apparatus called the mitotic spindle latches onto the chromosomes before pulling them apart. The mitotic spindle is a bundle of long, thin filaments called microtubules. It attaches to chromosomes at the kinetochore, the point where two copied chromosomes are cinched together in their middle. Proper cell division is vital for the healthy growth of all organisms, big and small, and yet some parts of the process remain poorly understood despite extensive study. Specifically, there is more to learn about how the mitotic spindle self-assembles, and how microtubules and kinetochores work together to correctly orient and segregate chromosomes into two sister cells. These nanoscale processes are happening a hundred times a minute, so computer simulations are a good way to test what we know. Edelmaier et al. developed a computer model to simulate cell division in fission yeast, a species of yeast often used to study fundamental processes in the cell. The model simulates how the mitotic spindle assembles, how its microtubules attach to the kinetochore and the force required to pull two sister chromosomes apart. Building the simulation involved modelling interactions between the mitotic spindle and kinetochore, their movement and forces applied. To test its accuracy, model simulations were compared to recordings of the mitotic spindle – including its length, structure and position – imaged from dividing yeast cells. Running the simulation, Edelmaier et al. found that several key effects are essential for the proper movement of chromosomes in mitosis. This includes holding chromosomes in the correct orientation as the mitotic spindle assembles and controlling the relative position of microtubules as they attach to the kinetochore. Misaligned attachments must also be readily deconstructed and corrected to prevent any errors. The simulations also showed that kinetochores must begin to exert more force (to separate the chromosomes) once the mitotic spindle is attached correctly. Altogether, these findings improve the current understanding of how the mitotic spindle and its counterparts control cell division. Errors in chromosome segregation are associated with birth defects and cancer in humans, and this new simulation could potentially now be used to help make predictions about how to correct mistakes in the process.
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Affiliation(s)
| | - Adam R Lamson
- Department of Physics, University of Colorado Boulder, Boulder, United States
| | - Zachary R Gergely
- Department of Physics, University of Colorado Boulder, Boulder, United States.,Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, United States
| | - Saad Ansari
- Department of Physics, University of Colorado Boulder, Boulder, United States
| | - Robert Blackwell
- Department of Physics, University of Colorado Boulder, Boulder, United States
| | - J Richard McIntosh
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, United States
| | - Matthew A Glaser
- Department of Physics, University of Colorado Boulder, Boulder, United States
| | - Meredith D Betterton
- Department of Physics, University of Colorado Boulder, Boulder, United States.,Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, United States
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11
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Zhou H, Zheng T, Wang T, Li Q, Wang F, Liang X, Chen J, Teng J. CCDC74A/B are K-fiber crosslinkers required for chromosomal alignment. BMC Biol 2019; 17:73. [PMID: 31521166 PMCID: PMC6744678 DOI: 10.1186/s12915-019-0694-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 08/29/2019] [Indexed: 12/26/2022] Open
Abstract
Background Spindle microtubule organization, regulated by microtubule-associated proteins, is critical for cell division. Proper organization of kinetochore fiber (K-fiber), connecting spindle poles and kinetochores, is a prerequisite for precise chromosomal alignment and faithful genetic material transmission. However, the mechanisms of K-fiber organization and dynamic maintenance are still not fully understood. Results We reveal that two previously uncharacterized coiled-coil domain proteins CCDC74A and CCDC74B (CCDC74A/B) are spindle-localized proteins in mammalian cells. They bind directly to microtubules through two separate domains and bundle microtubules both in vivo and in vitro. These functions are required for K-fiber organization, bipolar spindle formation, and chromosomal alignment. Moreover, CCDC74A/B form homodimers in vivo, and their self-association activity is necessary for microtubule bundling and K-fiber formation. Conclusions We characterize CCDC74A and CCDC74B as microtubule-associated proteins that localize to spindles and are important K-fiber crosslinkers required for bipolar spindle formation and chromosome alignment. Electronic supplementary material The online version of this article (10.1186/s12915-019-0694-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Haining Zhou
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education and State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, Beijing, 100871, China
| | - Tao Zheng
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education and State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, Beijing, 100871, China.,Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, 100871, China
| | - Tianning Wang
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education and State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, Beijing, 100871, China
| | - Qi Li
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education and State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, Beijing, 100871, China
| | - Fulin Wang
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education and State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, Beijing, 100871, China
| | - Xin Liang
- Peking-Tsinghua Center for Life Sciences and Max-Planck Partner Group, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Jianguo Chen
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education and State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, Beijing, 100871, China. .,Center for Quantitative Biology, Peking University, Beijing, 100871, China.
| | - Junlin Teng
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education and State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, Beijing, 100871, China.
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12
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Kouznetsova A, Kitajima TS, Brismar H, Höög C. Post-metaphase correction of aberrant kinetochore-microtubule attachments in mammalian eggs. EMBO Rep 2019; 20:e47905. [PMID: 31290587 PMCID: PMC6680117 DOI: 10.15252/embr.201947905] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 05/24/2019] [Accepted: 06/07/2019] [Indexed: 12/29/2022] Open
Abstract
The accuracy of the two sequential meiotic divisions in oocytes is essential for creating a haploid gamete with a normal chromosomal content. Here, we have analysed the 3D dynamics of chromosomes during the second meiotic division in live mouse oocytes. We find that chromosomes form stable kinetochore-microtubule attachments at the end of prometaphase II stage that are retained until anaphase II onset. Remarkably, we observe that more than 20% of the kinetochore-microtubule attachments at the metaphase II stage are merotelic or lateral. However, < 1% of all chromosomes at onset of anaphase II are found to lag at the spindle equator and < 10% of the laggards missegregate and give rise to aneuploid gametes. Our results demonstrate that aberrant kinetochore-microtubule attachments are not corrected at the metaphase stage of the second meiotic division. Thus, the accuracy of the chromosome segregation process in mouse oocytes during meiosis II is ensured by an efficient correction process acting at the anaphase stage.
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Affiliation(s)
- Anna Kouznetsova
- Department of Cell and Molecular BiologyKarolinska InstitutetStockholmSweden
| | - Tomoya S Kitajima
- Laboratory for Chromosome SegregationRIKEN Center for Biosystems Dynamics ResearchKobeJapan
| | - Hjalmar Brismar
- Science for Life LaboratoryDepartment of Applied PhysicsRoyal Institute of TechnologySolnaSweden
| | - Christer Höög
- Department of Cell and Molecular BiologyKarolinska InstitutetStockholmSweden
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13
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The mammalian kinetochore-microtubule interface: robust mechanics and computation with many microtubules. Curr Opin Cell Biol 2019; 60:60-67. [PMID: 31132675 DOI: 10.1016/j.ceb.2019.04.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 04/10/2019] [Accepted: 04/15/2019] [Indexed: 12/31/2022]
Abstract
The kinetochore drives chromosome segregation at cell division. It acts as a physical link between chromosomes and dynamic microtubules, and as a signaling hub detecting and processing microtubule attachments to control anaphase onset. The mammalian kinetochore is a large macromolecular machine that forms a dynamic interface with the many microtubules that it binds. While we know most of the kinetochore's component parts, how they work together to give rise to its robust functions remains poorly understood. Here we highlight recent findings that shed light on this question, driven by an expanding physical and molecular toolkit. We present emerging principles that underlie the kinetochore's robust microtubule grip, such as redundancy, specialization, and dynamicity, and present signal processing principles that connect this microtubule grip to robust computation. Throughout, we identify open questions, and define simple engineering concepts that provide insight into kinetochore function.
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14
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Olziersky AM, Smith CA, Burroughs N, McAinsh AD, Meraldi P. Mitotic live-cell imaging at different timescales. Methods Cell Biol 2018; 145:1-27. [PMID: 29957199 DOI: 10.1016/bs.mcb.2018.03.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Mitosis is a highly dynamic and choreographed process in which chromosomes are captured by the mitotic spindle and physically segregated into the two daughter cells to ensure faithful transmission of the genetic material. Live-cell fluorescence microscopy enables these dynamics to be analyzed over diverse temporal scales. Here we present the methodologies to study chromosome segregation at three timescales: we first show how automated tracking of kinetochores enables investigation of mitotic spindle and chromosome dynamics in the seconds-to-minutes timescale; next we highlight how new DNA live dyes allow the study of chromosome segregation over a period of several hours in any cell line; finally, we demonstrate how image sequences acquired over several days can reveal the fate of whole cell populations over several consecutive cell divisions.
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Affiliation(s)
- Anna-Maria Olziersky
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Chris A Smith
- Centre for Mechanochemical Cell Biology & Division of Biomedical Science, Warwick Medical School, University of Warwick, Coventry, United Kingdom
| | - Nigel Burroughs
- Mathematics Institute, University of Warwick, Coventry, United Kingdom
| | - Andrew D McAinsh
- Centre for Mechanochemical Cell Biology & Division of Biomedical Science, Warwick Medical School, University of Warwick, Coventry, United Kingdom.
| | - Patrick Meraldi
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland.
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15
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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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16
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Itoh G, Ikeda M, Iemura K, Amin MA, Kuriyama S, Tanaka M, Mizuno N, Osakada H, Haraguchi T, Tanaka K. Lateral attachment of kinetochores to microtubules is enriched in prometaphase rosette and facilitates chromosome alignment and bi-orientation establishment. Sci Rep 2018; 8:3888. [PMID: 29497093 PMCID: PMC5832872 DOI: 10.1038/s41598-018-22164-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 02/19/2018] [Indexed: 01/08/2023] Open
Abstract
Faithful chromosome segregation is ensured by the establishment of bi-orientation; the attachment of sister kinetochores to the end of microtubules extending from opposite spindle poles. In addition, kinetochores can also attach to lateral surfaces of microtubules; called lateral attachment, which plays a role in chromosome capture and transport. However, molecular basis and biological significance of lateral attachment are not fully understood. We have addressed these questions by focusing on the prometaphase rosette, a typical chromosome configuration in early prometaphase. We found that kinetochores form uniform lateral attachments in the prometaphase rosette. Many transient kinetochore components are maximally enriched, in an Aurora B activity-dependent manner, when the prometaphase rosette is formed. We revealed that rosette formation is driven by rapid poleward motion of dynein, but can occur even in its absence, through slow kinetochore movements caused by microtubule depolymerization that is supposedly dependent on kinetochore tethering at microtubule ends by CENP-E. We also found that chromosome connection to microtubules is extensively lost when lateral attachment is perturbed in cells defective in end-on attachment. Our findings demonstrate that lateral attachment is an important intermediate in bi-orientation establishment and chromosome alignment, playing a crucial role in incorporating chromosomes into the nascent spindle.
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Affiliation(s)
- Go Itoh
- Department of Molecular Oncology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, 980-8575, Japan
- Department of Molecular Medicine and Biochemistry, Akita University Graduate School of Medicine, Akita, 010-8543, Japan
| | - Masanori Ikeda
- Department of Molecular Oncology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, 980-8575, Japan
| | - Kenji Iemura
- Department of Molecular Oncology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, 980-8575, Japan
| | - Mohammed Abdullahel Amin
- Department of Molecular Oncology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, 980-8575, Japan
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Sei Kuriyama
- Department of Molecular Medicine and Biochemistry, Akita University Graduate School of Medicine, Akita, 010-8543, Japan
| | - Masamitsu Tanaka
- Department of Molecular Medicine and Biochemistry, Akita University Graduate School of Medicine, Akita, 010-8543, Japan
| | - Natsuki Mizuno
- Department of Molecular Oncology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, 980-8575, Japan
| | - Hiroko Osakada
- Advanced ICT Research Institute, National Institute of Information and Communications Technology (NICT), Kobe, 651-2492, Japan
| | - Tokuko Haraguchi
- Advanced ICT Research Institute, National Institute of Information and Communications Technology (NICT), Kobe, 651-2492, Japan
- Graduate School of Frontier Biosciences, Osaka University, Suita, 565-0871, Japan
- Graduate School of Science, Osaka University, Toyonaka, 560-0043, Japan
| | - Kozo Tanaka
- Department of Molecular Oncology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, 980-8575, Japan.
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17
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Abstract
Faithful chromosome segregation is accomplished by attachment of chromosomes to spindle microtubules using the kinetochore. In a major step forward in understanding the functional and structural complexity of kinetochores, a 21-subunit human centromere - kinetochore complex has been reconstituted entirely from purified components, recreating the connection between DNA and microtubule.
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Affiliation(s)
| | - Aaron F Straight
- Department of Biochemistry, Stanford Medical School, Stanford, CA, USA.
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18
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Suzuki A, Long SK, Salmon ED. An optimized method for 3D fluorescence co-localization applied to human kinetochore protein architecture. eLife 2018; 7:32418. [PMID: 29323636 PMCID: PMC5764572 DOI: 10.7554/elife.32418] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Accepted: 12/22/2017] [Indexed: 12/13/2022] Open
Abstract
Two-color fluorescence co-localization in 3D (three-dimension) has the potential to achieve accurate measurements at the nanometer length scale. Here, we optimized a 3D fluorescence co-localization method that uses mean values for chromatic aberration correction to yield the mean separation with ~10 nm accuracy between green and red fluorescently labeled protein epitopes within single human kinetochores. Accuracy depended critically on achieving small standard deviations in fluorescence centroid determination, chromatic aberration across the measurement field, and coverslip thickness. Computer simulations showed that large standard deviations in these parameters significantly increase 3D measurements from their true values. Our 3D results show that at metaphase, the protein linkage between CENP-A within the inner kinetochore and the microtubule-binding domain of the Ndc80 complex within the outer kinetochore is on average ~90 nm. The Ndc80 complex appears fully extended at metaphase and exhibits the same subunit structure in vivo as found in vitro by crystallography.
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Affiliation(s)
- Aussie Suzuki
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - Sarah K Long
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - Edward D Salmon
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, United States
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19
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Abstract
At metaphase in mitotic cells, pulling forces at the kinetochore-microtubule interface create tension by stretching the centromeric chromatin between oppositely oriented sister kinetochores. This tension is important for stabilizing the end-on kinetochore microtubule attachment required for proper bi-orientation of sister chromosomes as well as for satisfaction of the Spindle Assembly Checkpoint and entry into anaphase. How force is coupled by proteins to kinetochore microtubules and resisted by centromere stretch is becoming better understood as many of the proteins involved have been identified. Recent application of genetically encoded fluorescent tension sensors within the mechanical linkage between the centromere and kinetochore microtubules are beginning to reveal - from live cell assays - protein specific contributions that are functionally important.
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Affiliation(s)
- Edward D Salmon
- University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Kerry Bloom
- University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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20
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Kuhn J, Dumont S. Spindle assembly checkpoint satisfaction occurs via end-on but not lateral attachments under tension. J Cell Biol 2017; 216:1533-1542. [PMID: 28536121 PMCID: PMC5461026 DOI: 10.1083/jcb.201611104] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 03/30/2017] [Accepted: 04/26/2017] [Indexed: 11/22/2022] Open
Abstract
To ensure accurate chromosome segregation, the spindle assembly checkpoint (SAC) prevents anaphase until all kinetochores attach to the spindle. What signals the SAC monitors remains unclear. We do not know the contributions of different microtubule attachment features or tension from biorientation to SAC satisfaction nor how these possible cues change during attachment. In this study, we quantify concurrent Mad1 intensity and report on SAC silencing, real-time attachment geometry, occupancy, and tension at individual mammalian kinetochores. We show that Mad1 loss from the kinetochore is switch-like with robust kinetics and that tension across sister kinetochores is established just before Mad1 loss events at the first sister. We demonstrate that CenpE-mediated lateral attachment of the second sister can persistently generate this metaphase-like tension before biorientation, likely stabilizing sister end-on attachment, yet cannot induce Mad1 loss from that kinetochore. Instead, Mad1 loss begins after several end-on microtubules attach. Thus, end-on attachment provides geometry-specific molecular cues or force on specific kinetochore linkages that other attachment geometries cannot provide.
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Affiliation(s)
- Jonathan Kuhn
- Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA.,Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA
| | - Sophie Dumont
- Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA .,Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA.,Department of Cell and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA
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21
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Cdc20: At the Crossroads between Chromosome Segregation and Mitotic Exit. Trends Biochem Sci 2017; 42:193-205. [PMID: 28202332 DOI: 10.1016/j.tibs.2016.12.001] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 11/13/2016] [Accepted: 12/06/2016] [Indexed: 11/21/2022]
Abstract
Cell-division cycle protein 20 homologue (Cdc20) has important functions in chromosome segregation and mitotic exit. Cdc20 is the target of the spindle assembly checkpoint (SAC) and a key cofactor of the anaphase-promoting complex or cyclosome (APC/C) E3 ubiquitin ligase, thus regulating APC/C ubiquitin activity on specific substrates for their subsequent degradation by the proteasome. Here we discuss the roles of Cdc20 in SAC signalling and mitotic exit, describe how the integration of traditional approaches with emerging technologies has revealed new details of Cdc20 functions, comment about the potential of Cdc20 as a therapeutic target for the treatment of human malignancies, and discuss recent advances and controversies in the mechanistic understanding of the control of chromosome segregation during cell division.
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