Despite its sequence identity with canonical H4, Drosophila H4r product is enriched at specific chromatin regions
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ABSTRACT:
ORGANISM(S): Drosophila melanogaster
PROVIDER: GSE197256 | GEO | 2022/02/26
REPOSITORIES: GEO
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Project description:Chromatin integrates extracellular signals to regulate gene expression and, therefore, tightly controls development. Mutations in histone genes, including H3.3 and H4, were recently identified in children with developmental disorders characterized by intellectual disability and dysmorphic facial features1–7. However, the mechanistic and functional roles of these de novo, heterozygous germline mutations remain largely unknown. Here, we focus on the histone H4 lysine 91 to arginine (H4K91R) or glutamine (H4K91Q) mutations located within the highly conserved core histone fold domain. Our findings demonstrate that H4K91 mutants form aberrant nuclear puncta in mouse embryonic stem cells (mESCs), as well as in differentiated neural cells in vitro and in vivo. Genome-wide analyses revealed that H4K91 mutants accumulate ectopically at H3.3 and H3K9me3-enriched heterochromatin regions. Mechanistically, H4K91 mutants demonstrated enhanced binding to histone H3 variant H3.3, and ablation of H3.3 or the H3.3-specific chaperone DAXX diminished the formation of H4 mutant puncta and enrichment at heterochromatin regions. Additionally, H4 mutant expression increased chromatin accessibility in mammalian cells. Phenotypically, H4 mutant mice exhibit reduced brain size and altered cortical neuron layers, reminiscent of microcephaly phenotypes observed in patients. Consistent with the altered brain development in vivo, the expression of H4 mutants alter developmental gene expression and accelerate pro-neural differentiation in cell culture models. Together, these studies reveal multiple concurrent pathogenic mechanisms of H4 mutants found in developmental disorders and further our understanding of how histone mutants regulate cell fate during development.
2023-10-19 | GSE231566 | GEO
Project description:Chromatin integrates extracellular signals to regulate gene expression and, therefore, tightly controls development. Mutations in histone genes, including H3.3 and H4, were recently identified in children with developmental disorders characterized by intellectual disability and dysmorphic facial features1–7. However, the mechanistic and functional roles of these de novo, heterozygous germline mutations remain largely unknown. Here, we focus on the histone H4 lysine 91 to arginine (H4K91R) or glutamine (H4K91Q) mutations located within the highly conserved core histone fold domain. Our findings demonstrate that H4K91 mutants form aberrant nuclear puncta in mouse embryonic stem cells (mESCs), as well as in differentiated neural cells in vitro and in vivo. Genome-wide analyses revealed that H4K91 mutants accumulate ectopically at H3.3 and H3K9me3-enriched heterochromatin regions. Mechanistically, H4K91 mutants demonstrated enhanced binding to histone H3 variant H3.3, and ablation of H3.3 or the H3.3-specific chaperone DAXX diminished the formation of H4 mutant puncta and enrichment at heterochromatin regions. Additionally, H4 mutant expression increased chromatin accessibility in mammalian cells. Phenotypically, H4 mutant mice exhibit reduced brain size and altered cortical neuron layers, reminiscent of microcephaly phenotypes observed in patients. Consistent with the altered brain development in vivo, the expression of H4 mutants alter developmental gene expression and accelerate pro-neural differentiation in cell culture models. Together, these studies reveal multiple concurrent pathogenic mechanisms of H4 mutants found in developmental disorders and further our understanding of how histone mutants regulate cell fate during development.
2023-10-19 | GSE231558 | GEO
Project description:Probing the rice genome for novel histone coding genes revealed a genera specific, histone H4 variant with several variations in N-terminal tail sequence motifs, expressing in a tissue-specific manner. Genetic perturbation of the H4 variant in rice led to defects in growth and fertility. Probing the chromatin binding sites of the H4 variant with a custom antibody revealed its binding at specific genes and its knockout led to mis-expression of stress-associated genes. Stress-challenged plants showed loss of the H4 variant and re-distribution of other H4 linked histone marks. In vitro reconstituted rice nucleosomes with H4 variant histones displayed atypical properties in terms of stability, intra-nucleosome binding and structure, when compared to the canonical nucleosomes.
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Project description:Probing the rice genome for novel histone coding genes revealed a genera specific, histone H4 variant with several variations in N-terminal tail sequence motifs, expressing in a tissue-specific manner. Genetic perturbation of the H4 variant in rice led to defects in growth and fertility. Probing the chromatin binding sites of the H4 variant with a custom antibody revealed its binding at specific genes and its knockout led to mis-expression of stress-associated genes. Stress-challenged plants showed loss of the H4 variant and re-distribution of other H4 linked histone marks. In vitro reconstituted rice nucleosomes with H4 variant histones displayed atypical properties in terms of stability, intra-nucleosome binding and structure, when compared to the canonical nucleosomes.
2025-02-10 | GSE229599 | GEO
Project description:Probing the rice genome for novel histone coding genes revealed a genera specific, histone H4 variant with several variations in N-terminal tail sequence motifs, expressing in a tissue-specific manner. Genetic perturbation of the H4 variant in rice led to defects in growth and fertility. Probing the chromatin binding sites of the H4 variant with a custom antibody revealed its binding at specific genes and its knockout led to mis-expression of stress-associated genes. Stress-challenged plants showed loss of the H4 variant and re-distribution of other H4 linked histone marks. In vitro reconstituted rice nucleosomes with H4 variant histones displayed atypical properties in terms of stability, intra-nucleosome binding and structure, when compared to the canonical nucleosomes.
2025-02-10 | GSE229602 | GEO
Project description:The incorporation of histone H3 variants has been implicated in the epigenetic memory of cellular state. Using genome editing with zinc finger nucleases to tag endogenous H3.3, we report genome-wide profiles of H3 variants in mammalian embryonic stem (ES) cells and neuronal precursor cells. Genome-wide patterns of H3.3 are dependent on amino acid sequence, and change with cellular differentiation at developmentally regulated loci. The H3.3 chaperone Hira is required for H3.3 enrichment at active and repressed genes. Strikingly, Hira is not essential for localization of H3.3 at telomeres and many transcription factor binding sites. Immunoaffinity purification and mass spectrometry reveal that the proteins Atrx and Daxx associate with H3.3 in a Hira-independent manner. Atrx is required for Hira-independent localization of H3.3 at telomeres, and for the repression of telomeric RNA. Our data demonstrate that multiple and distinct factors are responsible for H3.3 localization at specific genomic locations in mammalian cells. Crosslinking ChIP-seq: Examination of 1 histone variant (H3.3), 2 histone modifications, and Serine-5 phosphorylated RNA polymerase in 2 different cell types (H3.3-HA ES samples 1-4, and H3.3-HA NPC samples 7-10). Examination of 1 histone variant (H3.2), and one histone modification (H3K36me3) in 2 different cell types (H3.2-HA ES samples 5-6, and H3.2-HA NPC samples 11-12). Examination of 1 histone variant (H3.3), input control, and one histone modification (H3K36me3) in one cell type (H3.3-HA hybrid ES, samples 13-15). Examination of 1 histone variant (H3.1S31), input control, and one histone modification (H3K36me3) in one cell type (H3.1S31-HA hybrid ES, samples 16-18). Native ChIP-seq: Examination of 1 histone variant (H3.3), input control, and one histone modification (H3K4me3) in one cell type (H3.3-HA ES, samples 19-21). Examination of 1 histone variant (H3.2), input control, and two histone modifications (H3K4me3 and H3K27me3) in one cell type (H3.2-HA ES, samples 22-25). Examination of 1 histone variant (H3.3), input control, and two histone modifications (H3K4me1 and H3K36me3) in one cell type (H3.3-EYFP ES, samples 26-29). Examination of 1 histone variant (H3.3), input control, and two histone modifications (H3K4me1 and H3K36me3) in one cell type (Hira -/- H3.3-EYFP ES, samples 30-33). Examination of 1 histone variant (H3.3) and input control in one cell type (Atrxflox H3.3-EYFP ES, samples 34-37). Examination of HA antibody background in one cell type (wild-type ES, sample 38).
2010-03-04 | E-GEOD-16893 | biostudies-arrayexpress
Project description:Centromeres are essential to ensure proper chromosome segregation in eukaryotes. Their definition relies on the presence of a centromere-specific H3 histone variant CenH3, known as CENP-A in mammals. Its overexpression in aggressive cancers raises questions concerning its effect on chromatin dynamics and contribution to tumorigenesis. We find that CenH3 overexpression in human cells leads to ectopic enrichment at sites of active histone turnover. Furthermore, in over-expressing conditions, we see the formation of a novel heterotypic particle (CenH3-H4/H3.3-H4) that occludes CTCF binding, but this occlusion has only a minor effect on gene expression. Ectopic localization and CTCF occlusion depends on the H3.3 chaperone DAXX, rather than its dedicated chaperone HJURP. This DAXX-dependent occlusion also occurs in naturally overexpressing cancer cells. Furthermore, our cellular model reveals a DAXX-dependent survival advantage when challenged by DNA damage. Our findings illustrate how changes in histone variant levels can disrupt chromatin dynamics in disease and provides a possible mechanism for cell resistance to anti-cancer treatments. Examination of CenH3 ChIP-seq and RNA-seq transcriptional programs in two conditions - WT and CenH3 over-expressing.
2014-02-12 | E-GEOD-42951 | biostudies-arrayexpress
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2012-03-05 | E-GEOD-34840 | biostudies-arrayexpress
Project description:Histone chaperones and chromatin remodelers control nucleosome dynamics, essential for transcription, replication, and DNA repair. The histone chaperone Anti-Silencing Factor 1 (ASF1) plays a central role in facilitating CAF-1-mediated replication-dependent H3.1 deposition and HIRA-mediated replication-independent H3.3 deposition in yeast and metazoans. Whether ASF1 function is evolutionarily conserved in plants is unknown. Here, we show that Arabidopsis ASF1 proteins display an exclusive preference for the H3.3-depositing HIRA complex. Simultaneous mutation of both Arabidopsis ASF1 genes caused a decrease in chromatin density and ectopic H3.1 occupancy at loci typically enriched with H3.3. Genetic, transcriptomic, and proteomic data indicate that ASF1 proteins strongly prefer the HIRA complex over CAF-1. asf1 mutants also displayed an increase in spurious Pol II transcriptional initiation, and showed defects in the maintenance of gene body CG DNA methylation and in the distribution of histone modifications. Furthermore, ectopic targeting of ASF1 caused excessive histone deposition, less accessible chromatin, and gene silencing. These findings reveal the importance of ASF1-mediated H3.3-H4 deposition via the HIRA pathway for proper epigenetic regulation of the genome.
2022-10-31 | PXD035578 | Pride
Project description:Paralogous variants of canonical histones guide accessibility to DNA and function as additional layers of genome regulation. Across eukaryotes, the occurrence, mechanism of action and functional significance of several variants of core histones are well known except that of histone H4. Here we show that a novel variant of H4 (H4.V), expressing tissue-specifically among members of Oryza genera, mediates specific epigenetic changes contributing majorly to salt tolerance. H4.V was incorporated to specific chromosomal locations where it blocked deposition of active histone marks. Under salt stress, large scale re-distribution of H4.V enabled incorporation of stress dependent histone H4 Lysine5 Acetylation (H4K5Ac) marks. Mis-expression of H4.V led to defects at morphological level especially in reproductive tissues, and in mounting stress responses. H4.V mediated these alterations by condensing chromatin at specific genomic regions as seen with cryo-EM structure of reconstituted H4.V containing nucleosomes. These results not only uncovered the presence of a H4 variant in plants, but also a novel chromatin regulation of stress responses that might have contributed to success of semi-aquatic Oryza members under variable water-limiting conditions.
2025-02-09 | GSE229604 | GEO