Regensburg 2022 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 13: Cytoskeleton

BP 13.4: Vortrag

Mittwoch, 7. September 2022, 10:30–10:45, H15

Torques within microtubule bundles generate the curved shape of the mitotic spindle — •Arian Ivec¹, Maja Novak¹, Monika Trupinić², Ivana Ponjavić², Iva Tolić², and Nenad Pavin¹ — ¹Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000 Zagreb, Croatia — ²Division of Molecular Biology, Ruder Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia

The mitotic spindle is a complex micro-machine made up of microtubules and associated proteins, which are highly ordered in space and time to ensure its proper biological functioning. A functional spindle has a characteristic shape, which includes curved bundles of microtubules that are twisted around the pole-to-pole axis. An understanding of both how the linear and rotational forces define the overall shape of the mitotic spindle and how the twisted shapes arise as a result of interactions between microtubules and motor proteins is still missing. To answer this, we model the entire spindle by using a mean-field approach, in which we describe the forces and torques along microtubule bundles throughout the spindle. We compare our theoretical modeling with experimentally observed shapes of bundles in the mitotic spindle, including both unperturbed spindles and those compressed by an external force. We conclude that the observed shape of the spindle is predominately determined by rotational forces. Additionally, we find that a difference in bending forces explains the disparity in the shapes of inner and outer bundles, and that the chirality of the spindle is the result of a constant twisting moment.