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Sds22 and Repo-Man stabilize chromosome segregation by counteracting Aurora B on anaphase kinetochores.

ABSTRACT: During mitotic spindle assembly, Aurora B kinase is part of an error correction mechanism that detaches microtubules from kinetochores that are under low mechanical tension. During anaphase, however, kinetochore-microtubule attachments must be maintained despite a drop of tension after removal of sister chromatid cohesion. Consistent with this requirement, Aurora B relocates away from chromosomes to the central spindle at the metaphase-anaphase transition. By ribonucleic acid interference screening using a phosphorylation biosensor, we identified two PP1-targeting subunits, Sds22 and Repo-Man, which counteracted Aurora B-dependent phosphorylation of the outer kinetochore component Dsn1 during anaphase. Sds22 or Repo-Man depletion induced transient pauses during poleward chromosome movement and a high incidence of chromosome missegregation. Thus, our study identifies PP1-targeting subunits that regulate the microtubule-kinetochore interface during anaphase for faithful chromosome segregation.

SUBMITTER: Wurzenberger C

PROVIDER: S-EPMC3410419 | biostudies-literature | 2012 Jul

REPOSITORIES: biostudies-literature

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Sds22 and Repo-Man stabilize chromosome segregation by counteracting Aurora B on anaphase kinetochores.

Wurzenberger Claudia C Held Michael M Lampson Michael A MA Poser Ina I Hyman Anthony A AA Gerlich Daniel W DW

The Journal of cell biology 20120716 2

During mitotic spindle assembly, Aurora B kinase is part of an error correction mechanism that detaches microtubules from kinetochores that are under low mechanical tension. During anaphase, however, kinetochore-microtubule attachments must be maintained despite a drop of tension after removal of sister chromatid cohesion. Consistent with this requirement, Aurora B relocates away from chromosomes to the central spindle at the metaphase-anaphase transition. By ribonucleic acid interference screen ...[more]

PMID: 22801782

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Project description:Accurate chromosome segregation during mitosis requires that all chromosomes establish stable bi-oriented attachments with the spindle apparatus. Kinetochores form the interface between chromosomes and spindle microtubules and as such are under tight control by complex regulatory circuitry. As part of the chromosomal passenger complex (CPC), the Aurora B kinase plays a central role within this circuitry by destabilizing improper kinetochore-microtubule attachments and relaying the attachment status to the spindle assembly checkpoint, a feedback control system that delays the onset of anaphase by inhibiting the anaphase-promoting complex/cyclosome. Intriguingly, Aurora B is conserved even in kinetoplastids, an evolutionarily divergent group of eukaryotes, whose kinetochores are composed of a unique set of structural and regulatory proteins. Kinetoplastids do not have a canonical spindle checkpoint and it remains unclear how their kinetochores are regulated to ensure the fidelity and timing of chromosome segregation. Here, we show in Trypanosoma brucei, the kinetoplastid parasite that causes African sleeping sickness, that inhibition of Aurora B using an analogue-sensitive approach arrests cells in metaphase, with a reduction in properly bi-oriented kinetochores. Aurora B phosphorylates several kinetochore proteins in vitro, including the N-terminal region of the divergent Bub1-like protein KKT14. Depletion of KKT14 partially overrides the cell cycle arrest caused by Aurora B inhibition, while overexpression of a non-phosphorylatable KKT14 protein results in a prominent delay in the metaphase-to-anaphase transition. Finally, we demonstrate using a nanobody-based system that re-targeting the catalytic module of the CPC to the outer kinetochore is sufficient to promote mitotic exit but causes massive chromosome mis-segregation in anaphase. Our results indicate that the CPC and KKT14 are involved in an unconventional pathway controlling mitotic exit and error-free chromosome segregation in trypanosomes.

Dataset Information

Sds22 and Repo-Man stabilize chromosome segregation by counteracting Aurora B on anaphase kinetochores.

Publications

Sds22 and Repo-Man stabilize chromosome segregation by counteracting Aurora B on anaphase kinetochores.

Similar Datasets

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