Dresden 2017 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 10: Cell Mechanics (Joint Session BP/DY)
DY 10.6: Talk
Monday, March 20, 2017, 16:30–16:45, SCH A251
Theory for forces that slide k-fibers and bridging microtubules to move chromosomes — •Agneza Bosilj1, Kruno Vukusic2, Renata Buda2, Ana Milas2, Iva Tolic2, and Nenad Pavin1 — 1Department of Physics, Faculty of Science, University of Zagreb, Bijenicka cesta 32, 10000 Zagreb, Croatia — 2Division of Molecular Biology, Ruder Boskovic Institute, Bijenicka cesta 54, 10000 Zagreb, Croatia
During cell division forces on chromosomes are exerted by k-fibers, bundles of microtubules which extend from the opposite spindle poles and attach to chromosomes. Recently we have shown that in metaphase microtubules which extend between sister chromatids, termed bridging fibers, bridge sister k-fibers and balance the tension between sister chromatids [Kajtez et al, Nat Commun 2016]. However, a theoretical description of forces driving chromosome segregation in anaphase is still missing. Here we introduce a theoretical model which includes motor proteins that connect antiparallel microtubules, as well as passive cross-linkers that connect parallel microtubules. Our model shows that motor proteins generate forces that slide antiparallel bridging microtubules apart, thereby sliding sister k-fibers apart. This implies that forces at chromosomes are balanced by bridging fibers, which we confirmed experimentally by laser ablation of (i) k-fibers close to the spindle pole and (ii) bridging fibers. Our model also predicts that non-motor cross-linkers in regions of parallel overlap allow for movement of k-fibers and chromosomes together with the bridging fiber.