Dresden 2020 – scientific programme
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BP: Fachverband Biologische Physik
BP 13: Cell Mechanics I
BP 13.2: Talk
Tuesday, March 17, 2020, 10:00–10:15, SCH A251
Bridging microtubules promote centering of kinetochores by length-dependent pulling forces — Agneza Bosilj1, Iva Tolic2, and •Nenad Pavin1 — 1Department of Physics, Faculty of Science, University of Zagreb — 2Ruder Bošković Institute, Zagreb
The mitotic spindle, by exerting forces, segregates chromosomes into two daughter cells during cell division. During metaphase, chromosome are positioned in the equatorial plane of the mitotic spindle, which is necessary to prevent lagging chromosomes and abnormal nuclear envelope reformation. It has been proposed that two centering mechanisms play a key role here, microtubule catastrophe promoted by kinesin-8 motors and pushing forces exerted by chromokinesins. Here we show, by combining a theoretical model and quantitative experiments, that kinetochore microtubules cross-linked by bridging microtubules exert length-dependent centering pulling forces. Our model also shows that length-dependent catastrophe and rescue regulated by motor proteins and passive cross-linkers are necessary for well defined length of microtubules and their antiparallel overlap, respectively. We predict that stable antiparallel overlaps exert length-dependent forces on kinetochores to navigate their positioning in the center of the metaphase plate.