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Project description:Histone H4 Lys 20 mono-methylation of the CENP-A nucleosome is essential for kinetochore assembly
| PRJDB2478 | ENA
Project description:Histone H4 Lys 20 mono-methylation of the CENP-A nucleosome is essential for kinetochore assembly
| PRJDB2480 | ENA
Project description:Histone H4 Lys 20 mono-methylation of the CENP-A nucleosome is essential for kinetochore assembly
| PRJDB2479 | ENA
Project description:Histone H4 Lys 20 mono-methylation of the CENP-A nucleosome is essential for kinetochore assembly
| PRJDB2481 | ENA
Project description:A key element for defining the centromere identity is the incorporation of a specific histone H3, CENP-A, known as Cnp1p in S. pombe. Previous studies have suggested that functional S. pombe centromeres lack nucleosome arrays and may involve chromatin remodeling as a key step of kinetochore assembly. We used tiling microarrays to show that nucleosomes are in fact positioned in regular intervals in the core of centromere 2, providing the first high resolution map of regional centromere chromatin. Nucleosome locations are not disrupted by mutations in kinetochore proteins cnp1, mis18, mis12, nuf2, mal2, overexpression of Cnp1p, or deletion of ams2. Bioinformatic analysis of the centromere sequence indicates certain enriched motifs in linker regions between nucleosomes and reveals a sequence-bias in nucleosome positioning. We conclude that centromeric nucleosome positions are stable and may be derived from the underlying DNA sequence. In addition, sequence analysis of nucleosome-free regions identifies novel binding sites for the GATA-like protein Ams2p, which participates in CENP-A incorporation. Keywords: Nucleosome Mapping Study Entire cnt regions and histone-related genes were tiled at 1-5 bp spacing using 60-mer probes.
2008-05-30 | E-GEOD-10742 | biostudies-arrayexpress
Project description:The CENP-T/-W histone fold complex, as an integral part of the inner kinetochore, is essential for building a proper kinetochore at the centromere in order to direct chromosome segregation during mitosis. Notably, CENP-T/-W is not inherited at centromeres and new deposition is absolutely required at each cell cycle for kinetochore function. However, the mechanisms underlying this new deposition of CENP-T/-W at centromeres are unclear. Here, we find that CENP-T deposition at centromeres is uncoupled from DNA synthesis. We identify Spt16 and SSRP1, subunits of the H2A-H2B histone chaperone FACT, as CENP-W binding partners through a proteomic screen. We find that the C-terminal region of Spt16 binds specifically to the histone fold region of CENP-T/-W. Furthermore, depletion of Spt16 impairs CENP-T and CENP-W deposition at endogenous centromeres and site directed targeting of Spt16 alone is sufficient to ensure local de novo CENP-T accumulation. We propose a model in which the FACT chaperone stabilizes the soluble CENP-T/-W complex in the cell and promotes dynamics of exchange, enabling CENP-T/-W deposition at centromeres.
2016-06-14 | PXD004099 | Pride
Project description:The centromere is a vital locus on each chromosome which seeds the kinetochore, allowing for a physical connection between the chromosome and the mitotic spindle. At the heart of the centromere is the centromere-specific histone H3 variant CENP-A/CENH3. Throughout the cell cycle the constitutive centromere associated network is bound to CENP-A chromatin, but how this protein network modifies CENP-A nucleosome dynamics in vivo is unknown. Here, using a combination of biophysical and biochemical analyses we provide evidence for the existence of two populations of structurally distinct CENP-A nucleosomes that co-exist at human centromeres. These two populations display unique sedimentation patterns in a glycerol gradient, and CENP-A nucleosomes that are physically associated with the inner kinetochore appear stabilized in an octameric conformation, with restricted access to the nucleosomal DNA by DNase I. In contrast, the bulk population of CENP-A nucleosomes have diminished heights and weakened DNA interactions. These data suggest that, in vivo, a reserve pool of immature CENP-A nucleosomes exist which wrap DNA loosely, whereas an active inner kinetochore complex associates with stabilized CENP-A nucleosomes. Our data have implications for a function for CENP-A that may be independent of its role in mitotis.
2020-04-02 | GSE129351 | GEO
Project description:The centromeric histone H3 variant CENP-A is overexpressed in many cancers. The mislocalization of CENP-A to noncentromeric regions contributes to chromosomal instability (CIN), a hallmark of cancer. However, pathways that promote or prevent CENP-A mislocalization remain poorly defined. Here, we performed a genome-wide RNAi screen for regulators of CENP-A localization which identified DNAJC9, a J-domain protein implicated in histone H3–H4 protein folding, as a factor restricting CENP-A mislocalization. Cells lacking DNAJC9 exhibit mislocalization of CENP-A throughout the genome, and CIN phenotypes. Global interactome analysis showed that DNAJC9 depletion promotes the interaction of CENP-A with the DNA-replication-associated histone chaperone MCM2. CENP-A mislocalization upon DNAJC9 depletion was dependent on MCM2, defining MCM2 as a driver of CENP-A deposition at ectopic sites when H3–H4 supply chains are disrupted. Cells depleted for histone H3.3, also exhibit CENP-A mislocalization. In summary, we have defined novel factors that prevent mislocalization of CENP-A, and demonstrated that the integrity of H3–H4 supply chains regulated by histone chaperones such as DNAJC9 restrict CENP-A mislocalization and CIN.
2024-04-11 | PXD043961 | Pride
Project description:Centromeric localization of the evolutionarily conserved histone H3 variant, CENP-A. is essential for chromosomal stability. CENP-A overexpression (OE) causesd its mislocalization to non-centromeric regions resulting in chromosomal instability (CIN) in yeast, flies and human cells. CENP-A OE and mislocalization have been observed in cancers and correlates with poor prognosis. However, the molecular consequences of CENP-A OE on CIN and aneuploidy have not been defined. Here, we overexpressed YFP-CENP-A in a pseudodiploid DLD1 cell line and showed that CENP-A OE leads to its mislocalization and CIN due to defects in kinetochore integrity and kinetochore-microtubule attachments. CENP-A OE also leads to its mislocalization and CIN in a xenograft mouse model. Under these conditions, it contributes to aneuploidy with karyotypic heterogeneity in human cells and xenograft mouse model. In summary, our studies provide a molecular link between CENP-A OE and aneuploidy, and suggest that karyotypic heterogeneity may contribute to the aggressive phenotype of CENP-A overexpressing cancers.
2020-07-16 | GSE154460 | GEO
Project description:The centromere specific histone H3 variant CENP-A/CENH3 specifies where the kinetochore is formed in most eukaryotes. Despite tight regulation of CENP-A levels in normal cells, overexpression of CENP-A is a feature shared by various types of solid tumors and results in its mislocalization to non-centromeric DNA. How CENP-A is assembled ectopically and the consequences of this mislocalization remain topics of high interest. Here, we report that in human colon cancer cells, the H3.3 chaperones HIRA and DAXX promote ectopic CENP-A deposition. Moreover, the correct balance between levels of the centromeric chaperone HJURP and CENP-A is essential to preclude ectopic assembly by H3.3 chaperones. In addition, we find that ectopic localization can recruit kinetochore components, and correlates with mitotic defects and DNA damage in G1 phase. Finally, CENP-A occupancy at the 8q24 locus is also correlated with amplification and overexpression of the MYC gene within that locus. Overall, these data provide insights into the causes and consequences of histone variant mislocalization in human cancer cells.
2018-10-10 | GSE120230 | GEO