Aurora B defines its own chromosomal targeting by opposing the recruitment of the phosphatase scaffold Repo-Man

Aurora B is the catalytic subunit of the chromosomal passenger complex (CPC), which orchestrates mitotic processes by phosphorylating key regulatory proteins. During prometaphase, the CPC accumulates at the centromeres to control the spindle checkpoint and regulate kinetochore-microtubule interactions. The centromeric CPC binds to histone H3 phosphorylated at T3 (H3T3ph) by Aurora B-activated Haspin. The phosphatase PP1/Repo-Man counteracts Haspin by dephosphorylating H3T3ph at the chromosome arms, yet it is restricted from dephosphorylating centromeric H3T3ph during prometaphase. In this study, we demonstrate that Aurora B phosphorylates Repo-Man at S893, inhibiting its binding to histones. We also identify PP2A as a mitotic interactor of Repo-Man that dephosphorylates S893, facilitating Repo-Man ZM 447439 recruitment to chromosomes and promoting H3T3ph dephosphorylation by PP1. Thus, the coordinated action of PP1 and PP2A on Repo-Man serves to counterbalance Aurora B’s chromosomal targeting. We propose that the reciprocal feedback regulation of Haspin and Repo-Man by Aurora B generates a robust bistable mechanism that ensures centromeric targeting of the CPC during prometaphase.