title: Overlap microtubules link sister k-fibres and balance the forces on bi-oriented kinetochores.
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.
authors.affiliation: Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany.
authors.forename: Janko
authors.initials: J
authors.lastname: Kajtez
authors.affiliation: Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany.
authors.forename: Anastasia
authors.initials: A
authors.lastname: Solomatina
authors.affiliation: Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000 Zagreb, Croatia.
authors.forename: Maja
authors.initials: M
authors.lastname: Novak
authors.affiliation: Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany.|Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
authors.forename: Bruno
authors.initials: B
authors.lastname: Polak
authors.affiliation: Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
authors.forename: Kruno
authors.initials: K
authors.lastname: Vukušić
authors.affiliation: Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany.
authors.forename: Jonas
authors.initials: J
authors.lastname: Rüdiger
authors.affiliation: Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany.
authors.forename: Gheorghe
authors.initials: G
authors.lastname: Cojoc
authors.affiliation: Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
authors.forename: Ana
authors.initials: A
authors.lastname: Milas
authors.affiliation: Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany.|Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
authors.forename: Ivana
authors.initials: I
authors.lastname: Šumanovac Šestak
authors.affiliation: Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
authors.forename: Patrik
authors.initials: P
authors.lastname: Risteski
authors.affiliation: Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany.
authors.forename: Federica
authors.initials: F
authors.lastname: Tavano
authors.affiliation: Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany.
authors.forename: Anna H
authors.initials: AH
authors.lastname: Klemm
authors.affiliation: Department of Biological Sciences, Virginia Tech, 1015 Life Science Circle, Blacksburg, Virginia 24061, USA.|Virginia Bioinformatics Institute, Virginia Tech, 1015 Life Science Circle, Blacksburg, Virginia 24061, USA.
authors.forename: Emanuele
authors.initials: E
authors.lastname: Roscioli
authors.affiliation: Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh, EH9 3BF Scotland, UK.
authors.forename: Julie
authors.initials: J
authors.lastname: Welburn
authors.affiliation: Department of Biological Sciences, Virginia Tech, 1015 Life Science Circle, Blacksburg, Virginia 24061, USA.|Virginia Bioinformatics Institute, Virginia Tech, 1015 Life Science Circle, Blacksburg, Virginia 24061, USA.
authors.forename: Daniela
authors.initials: D
authors.lastname: Cimini
authors.affiliation: Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000 Zagreb, Croatia.
authors.forename: Matko
authors.initials: M
authors.lastname: Glunčić
authors.affiliation: Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000 Zagreb, Croatia.
authors.forename: Nenad
authors.initials: N
authors.lastname: Pavin
authors.affiliation: Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany.|Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
authors.forename: Iva M
authors.initials: IM
authors.lastname: Tolić
mesh_terms: D001696:Biomechanical Phenomena; D045744:Cell Line, Tumor; D006801:Humans; D018386:Kinetochores / Q000502:physiology*; D008870:Microtubules / Q000502:physiology*; D008954:Models, Biological