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Epigenetically induced paucity of histone H2A.Z stabilizes fission yeast ectopic centromeres

ABSTRACT: In most eukaryotes, the centromere is epigenetically defined by nucleosomes that contain the histone H3 variant centromere protein A (CENP-A). Specific targeting of the CENP-A-loading chaperone to the centromere is vital for stable centromere propagation; however, the existence of ectopic centromeres (neocentromeres) indicates that this chaperone can function in different chromatin environments. The mechanism responsible for accommodating the CENP-A chaperone at novel chromatin regions is poorly understood. Here, we report the identification of transient, immature neocentromeres in Schizosaccharomyces pombe, which show reduced association with the CENP-A chaperone Scm3 attributable to persistence of the histone H2A variant H2A.Z. Following acquisition of adjacent heterochromatin or relocation of the immature neocentromeres to subtelomeric regions, H2A.Z was depleted and Scm3 was replenished, leading to subsequent stabilization of the neocentromeres. These findings provide novel insights into histone variant-mediated epigenetic control of neocentromere establishment.

ORGANISM(S): Schizosaccharomyces pombe

PROVIDER: GSE37094 | GEO | 2013/11/03

SECONDARY ACCESSION(S): PRJNA158255

REPOSITORIES: GEO

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Epigenetically induced paucity of histone H2A.Z stabilizes fission yeast ectopic centromeres

Project description:In most eukaryotes, the centromere is epigenetically defined by nucleosomes that contain the histone H3 variant centromere protein A (CENP-A). Specific targeting of the CENP-A-loading chaperone to the centromere is vital for stable centromere propagation; however, the existence of ectopic centromeres (neocentromeres) indicates that this chaperone can function in different chromatin environments. The mechanism responsible for accommodating the CENP-A chaperone at novel chromatin regions is poorly understood. Here, we report the identification of transient, immature neocentromeres in Schizosaccharomyces pombe, which show reduced association with the CENP-A chaperone Scm3 attributable to persistence of the histone H2A variant H2A.Z. Following acquisition of adjacent heterochromatin or relocation of the immature neocentromeres to subtelomeric regions, H2A.Z was depleted and Scm3 was replenished, leading to subsequent stabilization of the neocentromeres. These findings provide novel insights into histone variant-mediated epigenetic control of neocentromere establishment. Comparison of chromosomal distributions of centromeric proteins and heterochromatin proteins between the NC survivors and their derivatives.

2013-11-03 | E-GEOD-37094 | biostudies-arrayexpress

Genome-wide maps of CENP-A nucleosomes in three neocentromere-containing cell lines

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2013-05-04 | E-GEOD-44724 | biostudies-arrayexpress

Genome-wide maps of chromatin state (heterochromatin H3K9me2 or centromeric histone H3 variant CENP-A/Cnp1) in heterozygous deletion diploid mhf2∆/+ and the meiotic haploid progeny of heterozygous deletion diploid wip1∆/+, mhf1∆/+ and mhf2∆/+.

Project description:We report the high-throughput profiling of histone modification (H3K9me2) or histone variant CNEP-A/Cnp1 in fission yeast Schizosaccharomyces pombe. By obtaining 1-10 ng immunoprecipitated DNA, we generated genome-wide H3K9me2 or CENP-A/Cnp1 maps of heterozygous deletion diploid mhf2∆/+ and the meiotic haploid progeny of heterozygous deletion diploid wip1∆/+, mhf1∆/+ and mhf2∆/+ in fission yeast. We find that centromere inactivation and neocentromere formation occur independently and postzygotically in single depletion of CENP-T-W-X-S.

2019-09-28 | GSE117954 | GEO

Ccp1 homodimer mediates chromatin integrity by antagonizing CENP-A loading

Project description:CENP-A is a centromere-specific histone 3 variant essential for centromere specification. CENP-A partially replaces canonical histone H3 at the centromeres. How the particular CENP-A/H3 ratio at centromeres is precisely maintained is unknown. It also remains unclear how CENP-A is excluded from non-centromeric chromatin. Here we identify Ccp1, an uncharacterized NAP family protein in fission yeast that antagonizes CENP-A loading at both centromeric and non-centromeric regions. Like the CENP-A loading factor HJURP, Ccp1 interacts with CENP-A, and is recruited to centromeres at the end of mitosis in a Mis16-dependent manner. These data indicate that factors with opposing CENP-A loading activities are recruited to centromeres. Furthermore, Ccp1 also cooperates with H2A.Z to evict CENP-A assembled in euchromatin. Structural analyses indicate that Ccp1 forms a homodimer that is required for its anti-CENP-A loading activity. Our study establishes mechanisms for maintenance of CENP-A homeostasis at centromeres and the prevention of ectopic assembly of centromeres. Examination of cnp1 distribution in one wild type (wt) and two ccp1 mutants.

2016-08-04 | E-GEOD-85166 | biostudies-arrayexpress

Structural basis for the assembly of Mis18a/b core modules

Project description:The centromere, defined by the enrichment of CENP-A (a Histone H3 variant) containing nucleosomes, is a specialised chromosomal locus that acts as a microtubule attachment site. To preserve centromere identity, CENP-A levels must be maintained through active CENP-A loading during the cell cycle. A central player mediating this process is the Mis18 complex (Mis18a, Mis18b and Mis18BP1), which recruits the CENP-A specific chaperone HJURP to centromeres for CENP-A deposition. Here, using a multi-pronged approach, we characterise the structure of the Mis18 complex and show that multiple hetero- and homo-oligomeric interfaces facilitate the hetero-octameric Mis18 complex assembly composed of 4 Mis18a, 2 Mis18b and 2 Mis18BP1. Evaluation of structure-guided/separation-of-function mutants reveals structural determinants essential for Mis18 complex assembly and centromere maintenance. Our results provide new mechanistic insights on centromere maintenance, highlighting that while Mis18a can associate with centromeres and deposit CENP-A independently of Mis18b, the latter is indispensable for the optimal level of CENP-A loading required for preserving the centromere identity.

2024-05-15 | PXD047345 | Pride

Structural basis for the assembly of Mis18a/b core modules

2024-09-25 | PXD052964 | Pride

Genome-wide maps of chromatin state (centromeric histone H3 variant CENP-A/Cnp1) in clr4∆ and the transformants from the deletion of clr4 in mhf2∆ (cen2_inactive) or mhf2+ (cen1_inactive).

Project description:We report the high-throughput profiling of histone variant CNEP-A/Cnp1 in fission yeast Schizosaccharomyces pombe. By obtaining 1-10 ng immunoprecipitated DNA, we generated genome-wide CENP-A/Cnp1 maps of clr4∆ and the transformants from the deletion of clr4 in mhf2∆ (cen2_inactive) or mhf2+ (cen1_inactive) in fission yeast. We find that heterochromatin is not required for the induction of centromere inactivation in mhf2∆ and the maintenance of neocentromere in mhf2+.

2019-09-28 | GSE131226 | GEO

Swr1 mediated H2A.ZPht1 incorporation designates centromere DNA for de novo CENP-ACnp1 assembly

Project description:The centromere is the location on each chromosome that directs the assembly of the kinetochore. The underlying hallmark of centromeres in most eukaryotes is the presence of specialised nucleosomes in which canonical histone H3 is replaced by the histone H3 variant CENP-A. The molecular events that mediate a programme to install CENP-A in place of histone H3, at centromeres and how the centromeric chromatin is reorganised for CENP-A assembly during cell cycle remain poorly characterised. Histone H2A variant, H2A.Z is linked to transcriptional competence, in maintaining heterochromatin silencing and enriched in CENP-A chromatin. Our analyses demonstrate that H2A.ZPht1 and the Swr1 complex are associated with CENP-ACnp1 chromatin in fission yeast. Swr1 and Msc1 regulate H2A.ZPht1 deposition at centromeres and along with H2A.ZPht1 maintain CENP-ACnp1 chromatin integrity. Additionally, they coordinate the deposition of CENP-ACnp1 through the cell cycle, coupled with eviction of histone H3 from centromeres. Based on our results, we propose that the centromere is programmed to the widespread incorporation of H2A.ZPht1 via Swr1, and that H2A.ZPht1 dynamics likely play a role in regulating centromeric chromatin by influencing CENP-A incorporation.

2020-12-01 | GSE106585 | GEO

Ccp1 homodimer mediates chromatin integrity by antagonizing CENP-A loading

2016-08-04 | GSE85166 | GEO

Hap2-Ino80 mediated transcription facilitates de novo establishment of CENP-A chromatin

Project description:Centromeres are maintained epigenetically by the presence of CENP-A, an evolutionarily-conserved histone H3 variant, which directs kinetochore assembly and hence, centromere function. To identify factors that promote assembly of CENP-A chromatin, we affinity selected solubilised fission yeast CENP-ACnp1 chromatin. All subunits of the Ino80 complex were enriched, including the auxiliary subunit Hap2. In addition to a role in maintenance of CENP-ACnp1 chromatin integrity at endogenous centromeres, Hap2 is required for de novo assembly of CENP-ACnp1 chromatin on naïve centromere DNA and promotes H3 turnover on centromere regions and other loci prone to CENP-ACnp1 deposition. Prior to CENP-ACnp1 chromatin assembly, Hap2 is required for transcription from centromere DNA. These analyses suggest that Hap2-Ino80 destabilises H3 nucleosomes on centromere DNA through transcription-mediated histone H3 turnover, driving the replacement of resident H3 nucleosomes with CENP-ACnp1 nucleosomes. These inherent properties define centromere DNA by directing a program that mediates CENP-ACnp1 assembly on appropriate sequences.

2020-05-27 | PXD016602 | Pride

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