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Nat Commun. 2016 Jan 5;7:10298. doi: 10.1038/ncomms10298.

Overlap microtubules link sister k-fibres and balance the forces on bi-oriented kinetochores.

Author information

1
Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany.
2
Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000 Zagreb, Croatia.
3
Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
4
Department of Biological Sciences, Virginia Tech, 1015 Life Science Circle, Blacksburg, Virginia 24061, USA.
5
Virginia Bioinformatics Institute, Virginia Tech, 1015 Life Science Circle, Blacksburg, Virginia 24061, USA.
6
Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh, EH9 3BF Scotland, UK.

Abstract

During metaphase, forces on kinetochores are exerted by k-fibres, bundles of microtubules that end at the kinetochore. Interestingly, non-kinetochore microtubules have been observed between sister kinetochores, but their function is unknown. Here we show by laser-cutting of a k-fibre in HeLa and PtK1 cells that a bundle of non-kinetochore microtubules, which we term 'bridging fibre', bridges sister k-fibres and balances the interkinetochore tension. We found PRC1 and EB3 in the bridging fibre, suggesting that it consists of antiparallel dynamic microtubules. By using a theoretical model that includes a bridging fibre, we show that the forces at the pole and at the kinetochore depend on the bridging fibre thickness. Moreover, our theory and experiments show larger relaxation of the interkinetochore distance for cuts closer to kinetochores. We conclude that the bridging fibre, by linking sister k-fibres, withstands the tension between sister kinetochores and enables the spindle to obtain a curved shape.

PMID:
26728792
PMCID:
PMC4728446
DOI:
10.1038/ncomms10298
[Indexed for MEDLINE]
Free PMC Article

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