1. Cell Biology
  2. Physics of Living Systems

Self-organization of kinetochore-fibers in human mitotic spindles

  1. William Conway  Is a corresponding author
  2. Robert Kiewisz
  3. Gunar Fabig
  4. Colm P Kelleher
  5. Hai-Yin Wu
  6. Maya Anjur-Dietrich
  7. Thomas Müller-Reichert
  8. Daniel J Needleman
  1. Harvard University, United States
  2. Technische Universität Dresden, Germany
https://doi.org/10.7554/eLife.75458
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  1. William Conway
  2. Robert Kiewisz
  3. Gunar Fabig
  4. Colm P Kelleher
  5. Hai-Yin Wu
  6. Maya Anjur-Dietrich
  7. Thomas Müller-Reichert
  8. Daniel J Needleman
(2022)
Self-organization of kinetochore-fibers in human mitotic spindles
eLife 11:e75458.
https://doi.org/10.7554/eLife.75458
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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. 2021) 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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Author details

  1. William Conway

    Department of Physics, Harvard University, Cambridge, United States
    For correspondence
    wconway@g.harvard.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-7532-4331

  2. Robert Kiewisz

    Experimental Center, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
    Competing interests
    The authors declare that no competing interests exist.

  3. Gunar Fabig

    Experimental Center, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-3017-0978

  4. Colm P Kelleher

    Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
    Competing interests
    The authors declare that no competing interests exist.

  5. Hai-Yin Wu

    Department of Physics, Harvard University, Cambridge, United States
    Competing interests
    The authors declare that no competing interests exist.

  6. Maya Anjur-Dietrich

    John A Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, United States
    Competing interests
    The authors declare that no competing interests exist.

  7. Thomas Müller-Reichert

    Experimental Center, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-0203-1436

  8. Daniel J Needleman

    Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
    Competing interests
    The authors declare that no competing interests exist.

Funding

NSF-Simons Foundation (Center for Mathematical and Statistical Analysis of Biology at Harvard,1764269)

  • William Conway
  • Colm P Kelleher
  • Hai-Yin Wu
  • Maya Anjur-Dietrich
  • Daniel J Needleman

NSF (Graduate Research Fellowship Program)

  • William Conway

Deutsche Forsschunggemeinshaft (MU 1423/8-2)

  • Robert Kiewisz
  • Gunar Fabig
  • Thomas Müller-Reichert

European Union Horizon (Marie Sklodowska-Curie Agreement,675737)

  • Robert Kiewisz
  • Thomas Müller-Reichert

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Copyright

© 2022, Conway et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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  1. William Conway
  2. Robert Kiewisz
  3. Gunar Fabig
  4. Colm P Kelleher
  5. Hai-Yin Wu
  6. Maya Anjur-Dietrich
  7. Thomas Müller-Reichert
  8. Daniel J Needleman
(2022)
Self-organization of kinetochore-fibers in human mitotic spindles
eLife 11:e75458.
https://doi.org/10.7554/eLife.75458

Share this article

https://doi.org/10.7554/eLife.75458

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Further reading

    1. Cell Biology
    2. Physics of Living Systems

    Three-dimensional structure of kinetochore-fibers in human mitotic spindles

    Robert Kiewisz, Gunar Fabig ... Thomas Müller-Reichert
    Research Article Updated

    During cell division, kinetochore microtubules (KMTs) provide a physical linkage between the chromosomes and the rest of the spindle. KMTs in mammalian cells are organized into bundles, so-called kinetochore-fibers (k-fibers), but the ultrastructure of these fibers is currently not well characterized. Here, we show by large-scale electron tomography that each k-fiber in HeLa cells in metaphase is composed of approximately nine KMTs, only half of which reach the spindle pole. Our comprehensive reconstructions allowed us to analyze the three-dimensional (3D) morphology of k-fibers and their surrounding MTs in detail. We found that k-fibers exhibit remarkable variation in circumference and KMT density along their length, with the pole-proximal side showing a broadening. Extending our structural analysis then to other MTs in the spindle, we further observed that the association of KMTs with non-KMTs predominantly occurs in the spindle pole regions. Our 3D reconstructions have implications for KMT growth and k-fiber self-organization models as covered in a parallel publication applying complementary live-cell imaging in combination with biophysical modeling (Conway et al., 2022). Finally, we also introduce a new visualization tool allowing an interactive display of our 3D spindle data that will serve as a resource for further structural studies on mitosis in human cells.