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Leeds BK, Kostello KF, Liu YY, Nelson CR, Biggins S, Asbury CL. Mechanical coupling coordinates microtubule growth. eLife 2023; 12:RP89467. [PMID: 38150374 PMCID: PMC10752587 DOI: 10.7554/elife.89467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2023] Open
Abstract
During mitosis, kinetochore-attached microtubules form bundles (k-fibers) in which many filaments grow and shorten in near-perfect unison to align and segregate each chromosome. However, individual microtubules grow at intrinsically variable rates, which must be tightly regulated for a k-fiber to behave as a single unit. This exquisite coordination might be achieved biochemically, via selective binding of polymerases and depolymerases, or mechanically, because k-fiber microtubules are coupled through a shared load that influences their growth. Here, we use a novel dual laser trap assay to show that microtubule pairs growing in vitro are coordinated by mechanical coupling. Kinetic analyses show that microtubule growth is interrupted by stochastic, force-dependent pauses and indicate persistent heterogeneity in growth speed during non-pauses. A simple model incorporating both force-dependent pausing and persistent growth speed heterogeneity explains the measured coordination of microtubule pairs without any free fit parameters. Our findings illustrate how microtubule growth may be synchronized during mitosis and provide a basis for modeling k-fiber bundles with three or more microtubules, as found in many eukaryotes.
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Affiliation(s)
- Bonnibelle K Leeds
- Department of Physiology & Biophysics, University of WashingtonSeattleUnited States
| | - Katelyn F Kostello
- Department of Physiology & Biophysics, University of WashingtonSeattleUnited States
| | - Yuna Y Liu
- Department of Physiology & Biophysics, University of WashingtonSeattleUnited States
| | - Christian R Nelson
- Basic Sciences Division, Fred Hutchinson Cancer Research CenterSeattleUnited States
| | - Sue Biggins
- Basic Sciences Division, Fred Hutchinson Cancer Research CenterSeattleUnited States
| | - Charles L Asbury
- Department of Physiology & Biophysics, University of WashingtonSeattleUnited States
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Leeds BK, Kostello KF, Liu YY, Nelson CR, Biggins S, Asbury CL. Mechanical coupling coordinates microtubule growth. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.29.547092. [PMID: 37905093 PMCID: PMC10614740 DOI: 10.1101/2023.06.29.547092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
During mitosis, kinetochore-attached microtubules form bundles (k-fibers) in which many filaments grow and shorten in near-perfect unison to align and segregate each chromosome. However, individual microtubules grow at intrinsically variable rates, which must be tightly regulated for a k-fiber to behave as a single unit. This exquisite coordination might be achieved biochemically, via selective binding of polymerases and depolymerases, or mechanically, because k-fiber microtubules are coupled through a shared load that influences their growth. Here, we use a novel dual laser trap assay to show that microtubule pairs growing in vitro are coordinated by mechanical coupling. Kinetic analyses show that microtubule growth is interrupted by stochastic, force-dependent pauses and indicate persistent heterogeneity in growth speed during non-pauses. A simple model incorporating both force-dependent pausing and persistent growth speed heterogeneity explains the measured coordination of microtubule pairs without any free fit parameters. Our findings illustrate how microtubule growth may be synchronized during mitosis and provide a basis for modeling k-fiber bundles with three or more microtubules, as found in many eukaryotes.
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Affiliation(s)
- Bonnibelle K. Leeds
- Physiology & Biophysics Department, University of Washington School of Medicine, Seattle WA, USA
| | - Katelyn F. Kostello
- Physiology & Biophysics Department, University of Washington School of Medicine, Seattle WA, USA
| | - Yuna Y. Liu
- Physiology & Biophysics Department, University of Washington School of Medicine, Seattle WA, USA
| | | | | | - Charles L. Asbury
- Physiology & Biophysics Department, University of Washington School of Medicine, Seattle WA, USA
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Gandhimathi R, Pinotsi D, Köhler M, Mansfeld J, Ashiono C, Kleele T, Pawar S, Kutay U. Super-resolution microscopy reveals focal organization of ER-associated Y-complexes in mitosis. EMBO Rep 2023; 24:e56766. [PMID: 37469276 PMCID: PMC10481662 DOI: 10.15252/embr.202356766] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 07/03/2023] [Accepted: 07/03/2023] [Indexed: 07/21/2023] Open
Abstract
During mitotic entry of vertebrate cells, nuclear pore complexes (NPCs) are rapidly disintegrated. NPC disassembly is initiated by hyperphosphorylation of linker nucleoporins (Nups), which leads to the dissociation of FG repeat Nups and relaxation of the nuclear permeability barrier. However, less is known about disintegration of the huge nuclear and cytoplasmic rings, which are formed by annular assemblies of Y-complexes that are dissociated from NPCs as intact units. Surprisingly, we observe that Y-complex Nups display slower dissociation kinetics compared with other Nups during in vitro NPC disassembly, indicating a mechanistic difference in the disintegration of Y-based rings. Intriguingly, biochemical experiments reveal that a fraction of Y-complexes remains associated with mitotic ER membranes, supporting recent microscopic observations. Visualization of mitotic Y-complexes by super-resolution microscopy demonstrates that they form two classes of higher order assemblies: large clusters at kinetochores and small, focal ER-associated assemblies. These, however, lack features qualifying them as persisting ring-shaped subassemblies previously proposed to serve as structural templates for NPC reassembly during mitotic exit, which helps to refine current models of nuclear reassembly.
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Affiliation(s)
- Rojapriyadharshini Gandhimathi
- Department of Biology, Institute of BiochemistryETH ZurichZurichSwitzerland
- Molecular Life Sciences Ph.D. ProgramZurichSwitzerland
| | | | - Mario Köhler
- Department of Biology, Institute of BiochemistryETH ZurichZurichSwitzerland
| | - Jörg Mansfeld
- Department of Biology, Institute of BiochemistryETH ZurichZurichSwitzerland
- The Institute of Cancer ResearchLondonUK
| | - Caroline Ashiono
- Department of Biology, Institute of BiochemistryETH ZurichZurichSwitzerland
| | - Tatjana Kleele
- Department of Biology, Institute of BiochemistryETH ZurichZurichSwitzerland
| | - Sumit Pawar
- Department of Biology, Institute of BiochemistryETH ZurichZurichSwitzerland
- Present address:
Myllia BiotechnologyViennaAustria
| | - Ulrike Kutay
- Department of Biology, Institute of BiochemistryETH ZurichZurichSwitzerland
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Nayak P, Chatterjee S, Paul R. Microtubule search-and-capture model evaluates the effect of chromosomal volume conservation on spindle assembly during mitosis. Phys Rev E 2023; 108:034401. [PMID: 37849183 DOI: 10.1103/physreve.108.034401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2023] [Accepted: 06/23/2023] [Indexed: 10/19/2023]
Abstract
Variation in the chromosome numbers can arise from the erroneous mitosis or fusion and fission of chromosomes. While the mitotic errors lead to an increase or decrease in the overall chromosomal substance in the daughter cells, fission and fusion keep this conserved. Variations in chromosome numbers are assumed to be a crucial driver of speciation. For example, the members of the muntjac species are known to have very different karyotypes with the chromosome numbers varying from 2n=70+3B in the brown brocket deer to 2n=46 in the Chinese muntjac and 2n=6/7 in the Indian muntjac. The chromosomal content in the nucleus of these closely related mammals is roughly the same and various chromosome fusion and fission pathways have been suggested as the evolution process of these karyotypes. Similar trends can also be found in lepidoptera and yeast species which show a wide variation of chromosome numbers. The effect of chromosome number variation on the spindle assembly time and accuracy is still not properly addressed. We computationally investigate the effect of conservation of the total chromosomal substance on the spindle assembly during prometaphase. Our results suggest that chromosomal fusion pathways aid the microtubule-driven search and capture of the kinetochore in cells with monocentric chromosomes. We further report a comparative analysis of the site and percentage of amphitelic captures, dependence on cell shape, and position of the kinetochore in respect to chromosomal volume partitioning.
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Affiliation(s)
- Pinaki Nayak
- School of Mathematical and Computational Sciences, Indian Association for the Cultivation of Science, Kolkata 700032, India
| | - Saptarshi Chatterjee
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia 30332, USA
| | - Raja Paul
- School of Mathematical and Computational Sciences, Indian Association for the Cultivation of Science, Kolkata 700032, India
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McAinsh AD, Kops GJPL. Principles and dynamics of spindle assembly checkpoint signalling. Nat Rev Mol Cell Biol 2023:10.1038/s41580-023-00593-z. [PMID: 36964313 DOI: 10.1038/s41580-023-00593-z] [Citation(s) in RCA: 44] [Impact Index Per Article: 44.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/22/2023] [Indexed: 03/26/2023]
Abstract
The transmission of a complete set of chromosomes to daughter cells during cell division is vital for development and tissue homeostasis. The spindle assembly checkpoint (SAC) ensures correct segregation by informing the cell cycle machinery of potential errors in the interactions of chromosomes with spindle microtubules prior to anaphase. To do so, the SAC monitors microtubule engagement by specialized structures known as kinetochores and integrates local mechanical and chemical cues such that it can signal in a sensitive, responsive and robust manner. In this Review, we discuss how SAC proteins interact to allow production of the mitotic checkpoint complex (MCC) that halts anaphase progression by inhibiting the anaphase-promoting complex/cyclosome (APC/C). We highlight recent advances aimed at understanding the dynamic signalling properties of the SAC and how it interprets various naturally occurring intermediate attachment states. Further, we discuss SAC signalling in the context of the mammalian multisite kinetochore and address the impact of the fibrous corona. We also identify current challenges in understanding how the SAC ensures high-fidelity chromosome segregation.
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Affiliation(s)
- 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.
| | - Geert J P L Kops
- Hubrecht Institute - KNAW (Royal Netherlands Academy of Arts and Sciences) and University Medical Centre Utrecht, Utrecht, The Netherlands.
- Oncode Institute, Utrecht, The Netherlands.
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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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Aurora B Tension Sensing Mechanisms in the Kinetochore Ensure Accurate Chromosome Segregation. Int J Mol Sci 2021; 22:ijms22168818. [PMID: 34445523 PMCID: PMC8396173 DOI: 10.3390/ijms22168818] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 08/11/2021] [Accepted: 08/13/2021] [Indexed: 11/29/2022] Open
Abstract
The accurate segregation of chromosomes is essential for the survival of organisms and cells. Mistakes can lead to aneuploidy, tumorigenesis and congenital birth defects. The spindle assembly checkpoint ensures that chromosomes properly align on the spindle, with sister chromatids attached to microtubules from opposite poles. Here, we review how tension is used to identify and selectively destabilize incorrect attachments, and thus serves as a trigger of the spindle assembly checkpoint to ensure fidelity in chromosome segregation. Tension is generated on properly attached chromosomes as sister chromatids are pulled in opposing directions but resisted by centromeric cohesin. We discuss the role of the Aurora B kinase in tension-sensing and explore the current models for translating mechanical force into Aurora B-mediated biochemical signals that regulate correction of chromosome attachments to the spindle.
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Renda F, Khodjakov A. Role of spatial patterns and kinetochore architecture in spindle morphogenesis. Semin Cell Dev Biol 2021; 117:75-85. [PMID: 33836948 PMCID: PMC8762378 DOI: 10.1016/j.semcdb.2021.03.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 03/25/2021] [Accepted: 03/25/2021] [Indexed: 12/30/2022]
Abstract
Mitotic spindle is a self-assembling macromolecular machine responsible for the faithful segregation of chromosomes during cell division. Assembly of the spindle is believed to be governed by the 'Search & Capture' (S&C) principle in which dynamic microtubules explore space in search of kinetochores while the latter capture microtubules and thus connect chromosomes to the spindle. Due to the stochastic nature of the encounters between kinetochores and microtubules, the time required for incorporating all chromosomes into the spindle is profoundly affected by geometric constraints, such as the size and shape of kinetochores as well as their distribution in space at the onset of spindle assembly. In recent years, several molecular mechanisms that control these parameters have been discovered. It is now clear that stochastic S&C takes place in structured space, where components are optimally distributed and oriented to minimize steric hindrances. Nucleation of numerous non-centrosomal microtubules near kinetochores accelerates capture, while changes in the kinetochore architecture at various stages of spindle assembly promote proper connection of sister kinetochores to the opposite spindle poles. Here we discuss how the concerted action of multiple facilitating mechanisms ensure that the spindle assembles rapidly yet with a minimal number of errors.
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Affiliation(s)
- Fioranna Renda
- Biggs Laboratory, Wadsworth Center, New York State Department of Health, Empire State Plaza, Albany, NY 12237, United States.
| | - Alexey Khodjakov
- Biggs Laboratory, Wadsworth Center, New York State Department of Health, Empire State Plaza, Albany, NY 12237, United States; Rensselaer Polytechnic Institute, Troy, NY 12180, United States.
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