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bioRxiv · 10.1101/2020.12.30.424837

Sliding of kinetochore fibers along bridging fibers helps center the chromosomes on the spindle

Risteski, P.·Jagric, M.·Tolic, I. M.
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Abstract

Chromosome alignment at the spindle equator promotes proper chromosome segregation and depends on pulling forces exerted at kinetochore fiber tips together with polar ejection forces. However, kinetochore fibers are also subjected to forces driving their poleward flux. Here we introduce a flux-driven centering model that relies on flux generated by forces within the overlaps of bridging and kinetochore fibers. This centering mechanism works so that the longer kinetochore fiber fluxes faster than the shorter one, moving the kinetochores towards the center. We developed speckle microscopy in human spindles and confirmed the key prediction that kinetochore fiber flux is length-dependent. Kinetochores are better centered when overlaps are shorter and the kinetochore fiber flux markedly slower than the bridging fiber flux. We identify Kif18A and Kif4A as overlap and flux regulators and NuMA as a fiber coupler. Thus, length-dependent sliding forces exerted by the bridging fiber onto kinetochore fibers promote chromosome alignment.

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Risteski, P., Jagric, M., Tolic, I. M.. 2021-01-01. Sliding of kinetochore fibers along bridging fibers helps center the chromosomes on the spindle. https://doi.org/10.1101/2020.12.30.424837

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