Current Biology
Volume 29, Issue 13, 8 July 2019, Pages 2120-2130.e7
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Article
Self-Organization of Minimal Anaphase Spindle Midzone Bundles

https://doi.org/10.1016/j.cub.2019.05.049Get rights and content
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Highlights

  • Spindle midzone-like minimal microtubule bundles robustly self-organize in vitro

  • PRC1 crosslinkers and KIF4A kinesins organize microtubules into well-defined bundles

  • The PRC1/KIF4A ratio controls the extent of antiparallel microtubule overlap

  • Kinesins organize microtubules by pulling mobile crosslinkers into full compaction

Summary

In anaphase spindles, antiparallel microtubules associate to form tight midzone bundles, as required for functional spindle architecture and correct chromosome segregation. Several proteins selectively bind to these overlaps to control cytokinesis. How midzone bundles assemble is poorly understood. Here, using an in vitro reconstitution approach, we demonstrate that minimal midzone bundles can reliably self-organize in solution from dynamic microtubules, the microtubule crosslinker PRC1, and the motor protein KIF4A. The length of the central antiparallel overlaps in these microtubule bundles is similar to that observed in cells and is controlled by the PRC1/KIF4A ratio. Experiments and computer simulations demonstrate that minimal midzone bundle formation results from promoting antiparallel microtubule crosslinking, stopping microtubule plus-end dynamicity, and motor-driven midzone compaction and alignment. The robustness of this process suggests that a similar self-organization mechanism may contribute to the reorganization of the spindle architecture during the metaphase to anaphase transition in cells.

Keywords

mitotic spindle
anaphase
spindle midzone
microtubule
motor protein
kinesin
self-organization
in vitro reconstitution
computer simulation
Cytosim

Cited by (0)

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Present address: The Hurlingham Academy, Peterborough Road, London SW6 3ED, UK

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Present address: The Royal Society, 6-9 Carlton House Terrace, London SW1Y 5AG, UK

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