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bioRxiv · 10.64898/2026.01.07.698278

Kinetochore Homeostasis is Maintained by Coordinated Chromatin Stabilization and Soluble Buffering

Sridhar, S.·Nakagawa, R.·Fukagawa, T.
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Abstract

Faithful chromosome segregation requires the coordinated assembly and maintenance of kinetochore complexes. However, the homeostatic mechanisms that maintain these multi-subunit assemblies remain unclear. CENP-T is a chromatin-bound linker that recruits the outer kinetochore modules via the CENP-T-W-S-X complex to form a functional kinetochore. Although CENP-T must be continuously replenished, how its steady-state levels are maintained is unknown. Here we demonstrate that CENP-T homeostasis is actively sustained by two spatially distinct pathways. Using covalent pulse-labeling, we find that CENP-T undergoes cell-cycle-coupled turnover rather than being stably inherited. In situ proximity labeling of chromatin-bound and soluble pools identifies regulators of CENP-T stability, including an unexpected role for the CENP-O complex in stabilizing soluble CENP-T. Mechanistically, CENP-S-X stabilizes chromatin-bound CENP-T through DNA-binding, whereas the CENP-O complex buffers a replenishment-competent CENP-T pool. Together, these conserved, spatially compartmentalized pathways establish an actively maintained homeostatic system that ensures robust kinetochore assembly and faithful chromosome segregation.

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Sridhar, S., Nakagawa, R., Fukagawa, T.. 2026-01-08. Kinetochore Homeostasis is Maintained by Coordinated Chromatin Stabilization and Soluble Buffering. https://doi.org/10.64898/2026.01.07.698278

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