Ontology highlight
ABSTRACT:
PROVIDER: PRJNA1300380 | ENA |
REPOSITORIES: ENA
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Project description:Post-translational modifications of histone tails alter chromatin accessibility to regulate gene expression. Some viruses exploit the importance of histone modifications by expressing histone mimetic proteins that contain histone-like sequences to sequester complexes that recognize modified histones. Here we identify an evolutionarily conserved and ubiquitously expressed, endogenous mammalian protein Nucleolar protein 16 (NOP16) that functions as a H3K27 mimic. NOP16 binds to EED in the H3K27 trimethylation PRC2 complex and to the H3K27 demethylase JMJD3. NOP16 knockout selectively globally increases H3K27me3, a heterochromatin mark, without altering methylation of H3K4, H3K9, or H3K36 or acetylation of H3K27. NOP16 is overexpressed and linked to poor prognosis in breast cancer. Depletion of NOP16 in breast cancer cell lines causes cell cycle arrest, decreases cell proliferation and selectively decreases expression of E2F target genes and of genes involved in cell cycle, growth and apoptosis. Conversely, ectopic NOP16 expression in triple negative breast cancer cell lines increases cell proliferation, cell migration and invasivity in vitro and tumor growth in vivo, while NOP16 knockout or knockdown has the opposite effect. Thus, NOP16 is a histone mimic that competes with Histone H3 for H3K27 methylation and demethylation. When it is overexpressed in cancer, it derepresses genes that promote cell cycle progression to augment breast cancer growth.
2025-06-14 | GSE234948 | GEO
Project description:Analyzed histones modifications: H3K9 H3K4 H3K27 H4K20
2015-12-24 | E-MTAB-3743 | biostudies-arrayexpress
Project description:The three-dimensional (3D) genome structure is essential for gene regulation and various genomic functions. CTCF plays a key role in organizing Topologically Associated Domains (TADs) and promoter-enhancer loops, contributing to proper cell differentiation and development. Although CTCF binds the genome with high sequence specificity, its binding sites are dynamically regulated during development, and aberrant CTCF binding is linked to diseases such as cancer and neurological disorders, and aging. However, the mechanisms controlling CTCF binding remain unclear. Here, we investigated the role of repressive chromatin modifications in CTCF binding using H3K9 methyltransferase-deficient immortalized mouse embryonic fibroblasts (iMEFs) and H3K27 methyltransferase EZH1/2 inhibitor. We found that H3K9 and H3K27 methylation regulate CTCF binding at distinct genomic regions, and their simultaneous loss induces drastic changes in CTCF binding. These changes were associated with alterations in 3D genome architecture and gene expression, suggesting that repressive chromatin modifications preserve proper chromatin organization by preventing aberrant CTCF binding. Additionally, while CTCF binding sites repressed by H3K9 methylation were bound by CTCF in early mouse embryos, those repressed by both H3K9 and H3K27 methylation remained inaccessible, with early embryonic-specific H3K27 methylation forming at these sites. These findings implicate that H3K27 methylation prevents abnormal CTCF binding in early embryos, ensuring proper genome organization during development.
2025-07-17 | GSE293581 | GEO
Project description:The three-dimensional (3D) genome structure is essential for gene regulation and various genomic functions. CTCF plays a key role in organizing Topologically Associated Domains (TADs) and promoter-enhancer loops, contributing to proper cell differentiation and development. Although CTCF binds the genome with high sequence specificity, its binding sites are dynamically regulated during development, and aberrant CTCF binding is linked to diseases such as cancer and neurological disorders, and aging. However, the mechanisms controlling CTCF binding remain unclear. Here, we investigated the role of repressive chromatin modifications in CTCF binding using H3K9 methyltransferase-deficient immortalized mouse embryonic fibroblasts (iMEFs) and H3K27 methyltransferase EZH1/2 inhibitor. We found that H3K9 and H3K27 methylation regulate CTCF binding at distinct genomic regions, and their simultaneous loss induces drastic changes in CTCF binding. These changes were associated with alterations in 3D genome architecture and gene expression, suggesting that repressive chromatin modifications preserve proper chromatin organization by preventing aberrant CTCF binding. Additionally, while CTCF binding sites repressed by H3K9 methylation were bound by CTCF in early mouse embryos, those repressed by both H3K9 and H3K27 methylation remained inaccessible, with early embryonic-specific H3K27 methylation forming at these sites. These findings implicate that H3K27 methylation prevents abnormal CTCF binding in early embryos, ensuring proper genome organization during development.
2025-05-28 | GSE297986 | GEO
Project description:Herpesvirus latency is generally thought to be governed by epigenetic modifications, but the dynamics of viral chromatin at early timepoints of latent infection are poorly understood. Here, we report a comprehensive spatial and temporal analysis of epigenetic modifications during latent infection with Kaposi's sarcoma associated herpesvirus (KSHV), the etiologic agent of Kaposi's sarcoma and primary effusion lymphoma (PEL). Using high resolution tiling microarrays in conjunction with immunprecipitation of methylated DNA (MeDIP) and modified histones (ChIP), we have determined global patterns of epigenetic modifications across the KSHV genome in several tumor-derived cell lines as well as de novo infected endothelial cells, revealing highly distinct landscapes of epigenetic modifications associated with latent KSHV infection. We find that KSHV genomes are subject to profound methylation at CpG dinucleotides, leading to the establishment of characteristic global DNA methylation patterns. However, such patterns evolved slowly and thus are unlikely to govern latency early during the infection process. In contrast, we observed that latent histone modification patterns were rapidly established upon a de novo infection. Our analysis furthermore demonstrates that such patterns are not characterized by the absence of activating histone modifications, since both H3K9/K14-ac and H3K4-me3 marks were prominently detected at several loci, including the promoter of the lytic cycle transactivator Rta. While these regions were furthermore largely devoid of the constitutive heterochromatin marker H3K9-me3, we observed rapid and widespread deposition of H3K27-me3 across latent KSHV genomes, a bivalent modification which is able to repress transcription despite of the simultaneous presence of activating marks. Our findings suggest that the epigenetic patterns identified here induce a poised state of repression during viral latency, which can be rapidly reversed once the lytic cycle is induced. This dataset contains our ChIP-on-chip data; the MeDIP data are deposited in a separate dataset.
2010-06-07 | GSE19906 | GEO
Project description:Epigenetic mechanisms including histone modifications play key roles in the pathogenesis of multiple myeloma (MM). We have previously shown that a histone H3 lysine 27 (H3K27) methyltransferase EZH2 and a H3K9 methyltransferase G9a are potential therapeutic targets in MM. Recent studies suggested that EZH2 and G9a cooperate to regulate gene expression. We thus aimed to evaluate the anti-tumor effect by dual targeting of EZH2 and G9a in MM. A combination of an EZH2 inhibitor and a G9a inhibitor strongly suppressed myeloma cell proliferation through inducing cell cycle arrest and apoptosis in vitro. Dual inhibition of EZH2 and G9a also repressed xenograft formation by myeloma cells in vivo. Higher expression levels of EZH2 and EHMT2, which encodes G9a, are significantly associated with poorer prognosis in MM patients, respectively. Microarray analysis revealed that EZH2/G9a inhibition significantly upregulated interferon (IFN)-stimulated genes and suppressed IRF4-MYC axis genes in myeloma cells. Notably, we found increased expression and reduced H3K27/H3K9 methylation levels of endogenous retrovirus (ERV) genes in myeloma cells with the dual inhibition, suggesting that activation of the ERV genes may cause the IFN response. These results suggest that dual targeting of EZH2 and G9a may be a novel therapeutic strategy in MM.
2021-01-27 | GSE155135 | GEO
Project description:We report the application of single-molecule-based sequencing technology for high-throughput profiling of histone modifications in mammalian cells and characterized genome-wide SetDB1 binding and H3K9 trimethylation (H3K9me3) profiles in mouse ES cells and uncovered two distinct classes of SetDB1 binding sites, termed solo and ensemble peaks. The solo peaks were devoid of H3K9me3 and enriched near developmental regulators while the ensemble peaks were associated with H3K9me3. A subset of the SetDB1 solo peaks, particularly those near neural development related genes, was found to be associated with Polycomb Repressive Complex 2 (PRC2) as well as PRC2-interacting proteins Jarid2 and Mtf2. Genetic deletion of Setdb1 dramatically reduced Ezh2 binding as well as histone 3 lysine 27 (H3K27) trimethylation level at SetDB1 solo peaks and facilitated neural differentiation. Furthermore, we found that H3K27me3 inhibits SetDB1 methyltransferase activity in vitro. The currently identified reciprocal action between SetDB1 and PRC2 reveals a novel mechanism underlying ES cell pluripotency and differentiation regulation. Examination of 2 different histone modifications in 2 cell status.
2015-06-25 | E-GEOD-62666 | biostudies-arrayexpress
Project description:Heterochromatin is a key architectural feature of eukaryotic chromosomes, which is critical for cell type specific gene expression and genome stability. In the mammalian nucleus, heterochromatin is segregated from transcriptionally active genomic regions, and exists as large condensed and inactive nuclear compartment. However, the underlying mechanism of spatial organization of heterochromatin is still poorly understood. Histone H3 lysine 9 di- and tri-methylation (H3K9me2/3) and lysine 27 trimethylation (H3K27me3) are two major epigenetic modifications that define constitutive and facultative heterochromatin, respectively. In mammals, there are at least five H3K9 methyltransferases (SUV39H1, SUV39H2, SETDB1, G9a and GLP) and two H3K27 methyltransferases (EZH1 and EZH2). In this study, we addressed the role of H3K9 and H3K27 methylation in heterochromatin organization by using a combination of compound mutant cells for the five H3K9 methyltransferases and an EZH1/2 dual inhibitor, DS3201. We show that H3K27me3, which is normally segregated from H3K9me2/3, was redistributed to regions targeted by H3K9me2/3 after the loss of H3K9 methylation, and loss of both H3K9 and H3K27 methylation resulted in impaired both condensation and spatial organization of heterochromatin. Our data demonstrate that the two major repressive epigenome pathways exclusively but also coordinately maintain H3K9me2/3-marked heterochromatin organization in mammalian cells.
2022-04-05 | GSE200011 | GEO
Project description:Heterochromatin is a key architectural feature of eukaryotic chromosomes, which is critical for cell type specific gene expression and genome stability. In the mammalian nucleus, heterochromatin is segregated from transcriptionally active genomic regions, and exists as large condensed and inactive nuclear compartment. However, the underlying mechanism of spatial organization of heterochromatin is still poorly understood. Histone H3 lysine 9 di- and tri-methylation (H3K9me2/3) and lysine 27 trimethylation (H3K27me3) are two major epigenetic modifications that define constitutive and facultative heterochromatin, respectively. In mammals, there are at least five H3K9 methyltransferases (SUV39H1, SUV39H2, SETDB1, G9a and GLP) and two H3K27 methyltransferases (EZH1 and EZH2). In this study, we addressed the role of H3K9 and H3K27 methylation in heterochromatin organization by using a combination of compound mutant cells for the five H3K9 methyltransferases and an EZH1/2 dual inhibitor, DS3201. We show that H3K27me3, which is normally segregated from H3K9me2/3, was redistributed to regions targeted by H3K9me2/3 after the loss of H3K9 methylation, and loss of both H3K9 and H3K27 methylation resulted in impaired both condensation and spatial organization of heterochromatin. Our data demonstrate that the two major repressive epigenome pathways exclusively but also coordinately maintain H3K9me2/3-marked heterochromatin organization in mammalian cells.
2022-04-05 | GSE200014 | GEO
Project description:Histone lysine acetylation and methylation regulate gene transcription through coordination of chromatin structure and transcriptional activity. However, our understanding of the role of histones in gene regulation is far from complete, in part due to newly discovered novel histone modifications, whose functions are yet to be uncovered1. Here we report that histone H3 lysine 27 crotonylation (H3K27cr) is selectively recognized by the YEATS domain of GAS41 in association with SIN3a-HDAC1/2 co-repressor complex for gene transcriptional repression. The GAS41 YEATS domain dimer binds proto-oncogenic transcription factor c-Myc, which recruits GAS41/SIN3a-HDAC1/2 complex to target gene loci in chromatin such as cell cycle inhibitor p21. Transcriptional de-repression of p21, directed by tumor suppressor p53 upon doxorubicin stimulation, entails dissociation of c-Myc/GAS41/SIN3a-HDAC1/2 complex from chromatin, reduced H3K27 crotonylation, and consequentially increased H3K27 acetylation at p21 locus. GAS41 knockout or H3K27cr binding depletion with CRISPR/Cas9 results in p21 activation, cell cycle arrest and tumor growth inhibition in mice. Our study explains mechanistically causal effect of GAS41 and c-Myc gene amplification on down-regulation of p21 in human colorectal cancer, and suggests GAS41 as an anti-cancer target. We propose that H3K27 crotonylation represents a previously unrecognized, distinct chromatin state for gene transcriptional repression in contrast to H3K27 trimethylation for long-term transcriptional silencing and H3K27 acetylation for transcriptional activation.
2023-10-03 | GSE128590 | GEO