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

Kajtez, Janko; Solomatina, Anastasia; Novak, Maja; Polak, Bruno; Vukušić, Kruno; Rüdiger, Jonas; Cojoc, Gheorge; Milas, Ana; Šumanovac Šestak, Ivana; Risteski, Patrik; Tavano, Federica; H. Klemm, Anna; Roscioli, Emanuele; Welburn, Julie; Cimini, Daniela; Glunčić, Matko; Pavin, Nenad; Tolić, Iva M. (2016) Overlap microtubules link sister k-fibres and balance the forces on bi-oriented kinetochores. Nature Communications, 7 . ISSN 2041-1723

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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.

Item Type:	Article
Uncontrolled Keywords:	Kinetochores ; Microtubules ; Mitotic Spindle ; Metaphase
Subjects:	NATURAL SCIENCES > Physics NATURAL SCIENCES > Biology > Biochemistry and Molecular Biology
Divisions:	Division of Molecular Biology
Depositing User:	Iva Tolić
Date Deposited:	05 Mar 2019 12:05
URI:	http://fulir.irb.hr/id/eprint/4440
DOI:	10.1038/ncomms10298

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