Kinetochore-fiber lengths are maintained locally but coordinated globally by polesin the mammalian spindle
- University of California - San Francisco, United States
Abstract
At each cell division, nanometer-scale components self-organize to build a micron-scale spindle. In mammalian spindles, microtubule bundles called kinetochore-fibers attach to chromosomes and focus into spindle poles. Despite evidence suggesting that poles can set spindle length, their role remains poorly understood. In fact, many species do not have spindle poles. Here, we probe the pole's contribution to mammalian spindle length, dynamics, and function by inhibiting dynein to generate spindles whose kinetochore-fibers do not focus into poles, yet maintain a metaphase steady-state length. We find that unfocused kinetochore-fibers have a mean length indistinguishable from control, but a broader length distribution, and reduced length coordination between sisters and neighbors. Further, we show that unfocused kinetochore-fibers, like control, can grow back to their steady-state length if acutely shortened by drug treatment or laser ablation: they recover their length by tuning their end dynamics, albeit slower due to their reduced baseline dynamics. Thus, kinetochore-fiber dynamics are regulated by their length, not just pole-focusing forces. Finally, we show that spindles with unfocused kinetochore-fibers can segregate chromosomes but fail to correctly do so. We propose that mammalian spindle length emerges locally from individual k-fibers while spindle poles globally coordinate k-fibers across space and time.
Data availability
We provide all source data and analyzed data for all figures. We provide source code for Figure 1.
Article and author information
Author details
Funding
Achievement Rewards for College Scientists Foundation (Graduate Student Scholarship)
- Manuela Richter
Hertz Foundation (Hertz Fellowship)
- Lila Neahring
American Heart Association (Predoctoral Fellowship)
- Nathan H Cho
University of California, San Francisco (Discovery Fellows Program)
- Lila Neahring
- Nathan H Cho
National Science Foundation (Graduate Research Fellowship Program)
- Manuela Richter
University of California, San Francisco (PIBS Bishop Fellowship)
- Manuela Richter
National Institutes of Health (NIHR35GM136420)
- Sophie Dumont
National Science Foundation (NSF CAREER 1554139)
- Sophie Dumont
National Science Foundation (NSF 1548297 Center for Cellular Construction)
- Sophie Dumont
Chan Zuckerberg Initiative (Chan Zuckerberg Biohub)
- Sophie Dumont
University of California, San Francisco (Byers Award)
- Sophie Dumont
University of California, San Francisco (Program for Breakthrough Biomedical Research (PBBR))
- Sophie Dumont
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2023, Richter 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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Kinetochore-fiber lengths are maintained locally but coordinated globally by polesin the mammalian spindle
eLife 12:e85208.
https://doi.org/10.7554/eLife.85208
