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Bub1 and CENP-U redundantly recruit Plk1 to stabilize kinetochore-microtubule attachments and ensure accurate chromosome segregation

ABSTRACT: Bub1 is required for the kinetochore/centromere localization of two essential mitotic kinases Plk1 and Aurora B. Surprisingly, stable depletion of Bub1 by ~95% in human cells marginally affects whole chromosome segregation fidelity. We show that CENP-U, which is recruited to kinetochores by the CENP-P and CENP-Q subunits of the CENP-O complex, is required to prevent chromosome mis-segregation in Bub1-depleted cells. Mechanistically, Bub1 and CENP-U redundantly recruit Plk1 to kinetochores to stabilize kinetochore-microtubule attachments, thereby ensuring accurate chromosome segregation. Furthermore, unlike its budding yeast homolog, the CENP-O complex does not regulate centromeric localization of Aurora B. Consistently, depletion of Bub1 or CENP-U sensitizes cells to the inhibition of Plk1 but not Aurora B kinase activity. Taken together, our findings provide mechanistic insight into the regulation of kinetochore function, which may have implications for targeted treatment of cancer cells with mutations perturbing kinetochore recruitment of Plk1 by Bub1 or the CENP-O complex.

ORGANISM(S): Homo sapiens

PROVIDER: GSE182827 | GEO | 2021/08/29

REPOSITORIES: GEO

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Efficient checkpoint signaling depends on the integrated activities of Bub1 and the RZZ complex

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2019-02-19 | PXD012235 | Pride

Shugoshin biases chromosomes for biorientation through condensin recruitment to the pericentromere

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2014-01-08 | E-GEOD-53856 | biostudies-arrayexpress

Shugoshin biases chromosomes for biorientation through condensin recruitment to the pericentromere

2014-01-08 | GSE53856 | GEO

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2017-12-01 | PXD008316 | Pride

Centromere-Like Regions in Budding Yeast

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2013-01-18 | E-GEOD-31466 | biostudies-arrayexpress

Bub1 and CENP-U redundantly recruit Plk1 to stabilize kinetochore-microtubule attachments and ensure accurate chromosome segregation

Project description:Bub1 and CENP-U redundantly recruit Plk1 to stabilize kinetochore-microtubule attachments and ensure accurate chromosome segregation

| PRJNA758021 | ENA

Spodoptera frugiperda kinetochore co-immunoprecipitations

Project description:Accurate chromosome segregation requires assembly of the multiprotein kinetochore complex at centromeres. In most eukaryotes, kinetochore assembly is primed by the histone H3 variant CenH3, which physically interacts with components of the inner kinetochore constitutive-centromere-associated-network (CCAN). Unexpected to its critical function, previous work identified that select eukaryotic lineages, including several insects, have lost CenH3, while having retained homologs of the CCAN. These findings imply alternative CCAN assembly pathways in these organisms that function in CenH3-independent manners. Here, we study the composition and assembly of CenH3-independent kinetochores of Lepidoptera. We show that lepidopteran kinetochores consist of previously identified CCAN homologs as well as additional components including a divergent CENP-T homolog, which are required for accurate mitotic progression. Our study focuses on CENP-T that we find both necessary and sufficient to recruit the Mis12 outer kinetochore complex. In addition, CRISPR-mediated gene editing in Bombyx mori establishes an essential function of CENP-T in vivo. Finally, the retention of CENP-T homologs in other independently-derived CenH3-deficient insects indicates a conserved mechanism of kinetochore assembly between these lineages. Our study provides the first functional insights into CCAN-based kinetochore assembly pathways that function independently of CenH3, thus contributing to the emerging picture of an unexpected plasticity to build a kinetochore.

2020-02-18 | PXD016092 | Pride

Centromere-Like Regions in Budding Yeast

2013-01-18 | GSE31466 | GEO

Aurora A kinase phosphorylates Hec1 to regulate metaphase kinetochore-microtubule dynamics.

Project description:Precise regulation of kinetochore-microtubules is essential for successful chromosome segregation. Central to this regulation is Aurora B kinase, which phosphorylates kinetochore substrates to promote microtubule turnover. A critical target of Aurora B is the N-terminal “tail” domain of Hec1/NDC80, which is a component of the NDC80 complex, a force-transducing link between kinetochores and microtubules. While Aurora B is regarded as the “master regulator” of kinetochore-microtubule attachment, it is likely that other mitotic kinases contribute to Hec1phosphorylation. Here we show that Aurora A kinase phosphorylates the tail domain of Hec1 at Serine 69, a previously uncharacterized phosphorylation target site, and plays an important role in controlling kinetochore-microtubule attachment dynamics. Using phospho-specific antibodies, Hec1 phospho-deficient mutants, and kinase inhibitors, we demonstrate that Aurora A is required for the regulation of kinetochore-microtubule dynamics of metaphase chromosomes and identify Hec1 Serine 69 as a critical Aurora A substrate for this regulation. Additionally, we demonstrate that Aurora A kinase associates with INCENP during mitosis and that INCENP is competent to drive accumulation of the kinase to the centromere region of mitotic chromosomes. These findings reveal that both Aurora A and Aurora B contribute to kinetochore-microtubule attachment dynamics, and they uncover an unexpected role for Aurora A in mitosis.

2017-11-28 | PXD006892 | Pride

Expression profiles of histone point mutants

Project description:Accurate chromosome segregation requires that sister kinetochores biorient and attach to microtubules from opposite poles. Kinetochore biorientation relies on the underlying centromeric chromatin, which provides a platform to assemble the kinetochore and to recruit the regulatory factors that ensure the high fidelity of this process. To identify the centromeric chromatin determinants that contribute to chromosome segregation, we performed two complementary unbiased genetic screens using a library of mutants in every residue of histone H3 and H4. In one screen, we identified mutants that lead to increased loss of a non-essential chromosome. In the second screen, we isolated mutants whose viability depends on a key regulator of biorientation, the Aurora B protein kinase. Nine mutations, H3 Q5A, H3 R40A, H3 G44A, H3 R53A, H3 N108A, H3 L109A, H4 K44A, H4 V81A, and H4 Y98A, were common to both screens and exhibited kinetochore biorientation defects. Five of the mutants map near the unstructured nucleosome entry site and their genetic interaction with decreased Ipl1 function can be suppressed by increasing the dosage of the Sgo1 protein. In addition, the composition of purified kinetochores was altered in five of the mutants. Together, this work identifies previously unknown histone residues involved in chromosome segregation and lays the foundation for future studies of the role of the underlying chromatin structure in segregation.

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