Reconstitution of basic mitotic spindles in cell-like confinement

30 November 2018 - 13:30 PM

Marileen DogteromDelft University of Technology, Delft, Netherlands

Location: Amphi Astier, Building Esclangon, Tower 66

Abstract: Bipolar organization of the mitotic spindle is the result of forces generated by dynamic microtubules and associated proteins in interaction with chromosomes and the cell boundary. However, a quantitative understanding of the force balance that results from the concerted action of individual force-generation components is difficult to obtain. I will present an experimental platform based on water-in-oil emulsion droplets that allows for the bottom-up reconstitution of minimal spindles. We find a typical metaphase organization, where two microtubule asters position symmetrically at moderate distance from the mid-zone, is readily obtained even in the absence of chromosomes. Consistent with simulations, we observe an intrinsic repulsive force between two asters that can be counterbalanced alternatively by cortical pulling forces, anti-parallel microtubule cross linking, or adjustment of microtubule dynamics, emphasizing the robustness of the system. Adding motor proteins that slide anti-parallel microtubules apart drives the asters to maximum separation, as observed in cells during anaphase. Our platform offers a valuable complementary approach to in vivo experiments where essential mitotic components are typically removed, instead of added, one by one.

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