Homo sapiens
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ABSTRACT:
PROVIDER: PRJNA261535 | ENA |
REPOSITORIES: ENA
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Project description:Recent studies have identified a Lys 27-to-methionine (K27M) mutation at one allele of H3F3A, one of the two genes encoding histone H3 variant H3.3, in 60% of high-grade pediatric glioma cases. The median survival of this group of patients after diagnosis is ∼1 yr. Here we show that the levels of H3K27 di- and trimethylation (H3K27me2 and H3K27me3) are reduced globally in H3.3K27M patient samples due to the expression of the H3.3K27M mutant allele. Remarkably, we also observed that H3K27me3 and Ezh2 (the catalytic subunit of H3K27 methyltransferase) at chromatin are dramatically increased locally at hundreds of gene loci in H3.3K27M patient cells. Moreover, the gain of H3K27me3 and Ezh2 at gene promoters alters the expression of genes that are associated with various cancer pathways. These results indicate that H3.3K27M mutation reprograms epigenetic landscape and gene expression, which may drive tumorigenesis. We performed chromatin-immunoprecipitation of H3K27me3, H3K4me3, and EZH2 in SF7761 and NSC cell lines. And do RNA-seq in SF7761, SF8828 and NSC cell lines. SF7761 and SF8628 cell lines from patients harboring the histone H3.3 K27M mutation were obtained from Hashizume et al. (2012). NSCs (N7800-100) were purchased from Invitrogen and cultured and maintained in NSC medium (A10509-01, StemPro NSC SFM, Invitrogen).
2014-09-20 | E-GEOD-61586 | biostudies-arrayexpress
Project description:Recent studies have identified a Lys 27-to-methionine (K27M) mutation at one allele of H3F3A, one of the two genes encoding histone H3 variant H3.3, in 60% of high-grade pediatric glioma cases. The median survival of this group of patients after diagnosis is ∼1 yr. Here we show that the levels of H3K27 di- and trimethylation (H3K27me2 and H3K27me3) are reduced globally in H3.3K27M patient samples due to the expression of the H3.3K27M mutant allele. Remarkably, we also observed that H3K27me3 and Ezh2 (the catalytic subunit of H3K27 methyltransferase) at chromatin are dramatically increased locally at hundreds of gene loci in H3.3K27M patient cells. Moreover, the gain of H3K27me3 and Ezh2 at gene promoters alters the expression of genes that are associated with various cancer pathways. These results indicate that H3.3K27M mutation reprograms epigenetic landscape and gene expression, which may drive tumorigenesis.
2014-09-20 | GSE61586 | GEO
Project description:The regulation of gene expression is controlled in part by post-translational modifications to histone proteins. Methylation at histone H3, lysine 27 (H3K27), which is catalyzed by Polycomb repressive complex 2 (PRC2), is associated with silenced chromatin. Previous studies have identified dysregulation of H3K27 methylation in pediatric diffuse intrinsic pontine gliomas (DIPGs), the majority of which feature mutation of lysine 27 to methionine. This “oncohistone” potently inhibits PRC2 activity and leads to a global reduction in H3K27 methylation. Similar to DIPG, posterior fossa type A (PFA) ependymomas also show low levels of H3K27 methylation. Although PFAs do not possess the H3K27M oncohistone mutation, they do show increased expression of Cxorf67. Interestingly, Cxorf67 contains a C-terminal sequence that resembles the sequence surrounding H3K27, and we find that this portion of Cxorf67 inhibits PRC2 activity to an even greater extent than the H3K27M oncohistone. Thus, we suggest re-naming Cxorf67 as EZHIP (Enhancer of Zeste Homologs Inhibitory Protein). Furthermore, when expressed in 293T cells, Cxorf67 interacts with several members of PRC2 and induces changes in H3K27 methylation patterns that mirror the changes in H3K27 methylation induced by expression of H3K27M. We propose that PFAs have dysregulated H3K27 methylation by a mechanism that involves inhibition of PRC2 by Cxorf67, which could drive tumorigenesis.
2019-04-09 | PXD013390 | Pride
Project description:Diffuse intrinsic pontine gliomas (DIPG) are a deadly paediatric brain tumours, non-resectable due to brainstem localisation and diffusive growth. Patients with DIPG have a dismal prognosis of 9-12 months of survival with no effective therapy. Over 80% of DIPGs harbour a mutation in histone 3 (H3.3 or H3.1) resulting in a lysine to methionine substitution (H3K27M). H3K27M causes global epigenetic alterations (a loss of H3K27 trimethylation and an increase in H3K27 acetylation) resulting in aberrant gene expression. To date, no therapeutic strategy exists to suppress the levels of oncogenic H3K27M.
We show that pan-HDAC inhibitors (HDACi) lead to the temporary but significant reduction in the H3.33K27M protein (up to 80%) in multiple glioma cell lines expressing the H3.3K27M histone variant, without changes in the H3F3A mRNA expression. The H3.3K27M occupancy at the chromatin is greatly reduced upon HDACi (SB939) treatment, as shown by ChIPseq analysis. H3.3K27M loss is most striking at SB939-upregulated genes suggesting the role in repression of these genes. In addition, genes previously reported as H3K27M-dependent become downregulated in response to SB939 treatment. We discover that the SB939-mediated loss of H3.3K27M is partially blocked by a lysosomal inhibitor, chloroquine. Moreover, the loss of H3.3K27M is facilitated by co-occurrence of H2A.Z, as evidenced by the knock-down of H2A.Z histone isoforms. ChIPseq analysis confirms the occupancy of H3.3K27M and H2A.Z at the same SB939-inducible genes.
Altogether, we provide new insight into disease-specific mechanism of HDAC inhibition and demonstrate pharmacological modulation of the oncogenic H3.3K27M protein levels. These findings open a new possibility to directly target the H3.3K27M oncohistone, which may be exploited in future therapies.
2023-10-05 | MSV000093052 | MassIVE
Project description:Substitution of lysine 27 with methionine in histone H3.3 is a recently discovered driver mutation of pediatric high-grade gliomas. Tumor cells carrying the mutation show a dramatic decrease in H3K27me3 levels due to physical inhibition of PRC2 methyltransferase activity. Here we use a C. elegans model to quantify the antagonistic effects of the H3.3K27M oncohistone on H3K27 trimethylation genome wide. We demonstrate that PRC2 is locally both simulated by H3K27me3 and inhibited by the oncohistone in a concentration-dependent manner.
2019-04-26 | GSE117531 | GEO
Project description:Substitution of lysine 27 with methionine in histone H3.3 is a recently discovered driver mutation of pediatric high-grade gliomas. Tumor cells carrying the mutation show a dramatic decrease in H3K27me3 levels due to physical inhibition of PRC2 methyltransferase activity. Here we use a C. elegans model to quantify the antagonistic effects of the H3.3K27M oncohistone on H3K27 trimethylation genome wide. We demonstrate that PRC2 is locally both simulated by H3K27me3 and inhibited by the oncohistone in a concentration-dependent manner.
2019-04-26 | GSE117471 | GEO
Project description:Histone H3 lysine27-to-methionine (H3K27M) gain-of-function mutations occur in highly aggressive pediatric gliomas. Here, we establish a Drosophila animal model for the pathogenic histone H3K27M mutation and show that its overexpression resembles Polycomb repressive complex 2 (PRC2) loss-of-function phenotypes, causing de-repression of PRC2 target genes and developmental perturbations. Similarly, a H3K9M mutant depletes H3K9 methylation levels and suppresses position-effect variegation in various Drosophila tissues. The histone H3K9 demethylase KDM3B/JHDM2 associates with H3K9M nucleosomes and its overexpression in Drosophila results in loss of H3K9 methylation levels and heterochromatic silencing defects. Here we establish histone lysine-to-methionine mutants as robust in vivo tools for inhibiting methylation pathways that also function as biochemical reagents for capturing site-specific histone-modifying enzymes, thus providing molecular insight into chromatin-signaling pathways. RNA-seq of wing imaginal discs expressing either H3.3WT-FLAG-HA or H3.3K27M-FLAG-HA.
2014-09-02 | E-GEOD-59891 | biostudies-arrayexpress
Project description:The histone H3 variant, H3.3, is localized at specific regions in the genome, especially promoters and active enhancers, and has been shown to play important roles in development. A lysine to methionine substitution in position 27 (H3.3K27M) is a main cause of Diffuse Intrinsic Pontine Glioma, a lethal type of pediatric cancer. H3.3K27M has a dominant-negative effect by inhibiting the Polycomb Repressor Complex 2 (PRC2) activity. Here, we studied the immediate, genome-wide, consequences of the H3.3K27M mutation independent of PRC2 activity. We developed Doxycycline (Dox)-inducible mouse embryonic stem cells (ESCs) carrying a single copy of WT-H3.3, H3.3K27M and H3.3K27L, all fused to HA. We performed RNA-Seq and ChIP-Seq at different timepoints following Dox in undifferentiated and differentiated ESCs. We find increased binding of H3.3 around transcription start sites in cells expressing both H3.3K27M and H3.3K27L compared with WT, but not in cells treated with PRC2 inhibitors. Differentiated cells carrying either H3.3K27M or H3.3K27L retain expression of ESC-active genes, in expense of expression of genes related to neuronal differentiation. Taken together, our data suggest that a modifiable H3.3K27 is required for proper histone incorporation and cellular maturation, independent of PRC2 activity.
2022-09-01 | GSE195789 | GEO
Project description:Expression of histone H3.3K27M mutant proteins in diffuse intrinsic pontine glioma (DIPG) results in a global reduction of tri-methylation of H3K27 (H3K27me3), and paradoxically, H3K27me3 peaks remain at hundreds of genomic loci, a dichotomous change that lacks mechanistic insights. Here we show that the PRC2 complex is sequestered at poised enhancers, but not at active promoters with high levels of H3.3K27M proteins, thereby contributing to the global reduction of H3K27me3. Moreover, the levels of H3.3K27M proteins are low at the retained H3K27me3 peaks and consequently having minimal effects on the PRC2 activity at these loci. H3K27me3-mediated silencing at specific tumor suppressor genes, including Wilms Tumor 1, promotes proliferation of DIPG cells. These results support a model in which the PRC2 complex is redistributed to poised enhancers in H3.3K27M mutant cells and supports the proliferation of DIPG cells in part through silencing of tumor suppressor gene WT1.
2018-07-02 | GSE94834 | GEO
Project description:Epigenetic alterations are recurrently observed in cancer and are the subject of active therapeutic investigations. Midline high-grade gliomas (HGGs) are deadly brain tumors characterized by lysine-to-methionine substitutions at position 27 in histone 3 (H3) variants (denoted H3K27M), which are core components of the nucleosome. H3K27M, the first event in midline HGG development, results in a drastic loss of the repressive histone mark H3K27 tri-methylation (H3K27me3), and a notable increase in H3K27 acetylation (H3K27ac), a mark associated with active chromatin and cellular identity. H3K27ac gain was suggested to promote tumorigenesis in H3K27M-HGGs, but how these opposing marks shape oncogenesis remains controversial. We therefore characterized the active regulatory chromatin states in H3.3K27M and H3K27 wild-type HGGs and in H3.3K27M CRISPR/Cas9 knockout tumor-derived cell lines, as an isogenic tumor model of the mutation. We show that H3.3K27M-HGGs have distinct promoter, enhancer, super-enhancer, and core transcription factor circuitries from wild-type HGGs. However, while removal of H3.3K27M restores gross H3K27ac levels to those of wild-type HGGs, we observe minimal disruption of H3K27ac deposition at these active transcriptional elements, suggesting that they are a function of the cell of origin and independent of direct H3K27M mutagenesis and active regulation. Using quantitative ChIP-seq, we show that in H3.3K27M-HGGs, H3K27ac is pervasively deposited across the genome, including at normally silent repeat elements, leading to their increased baseline expression. H3.3K27M cells respond to DNA demethylating agents and histone deacetylase inhibitors, which further increase repeat element expression, including that of specific endogenous retroviral (ERVs) families. Our findings decouple cell lineage programs from H3K27M-dependent pervasive deposition of H3K27 acetylation. De-repression of ERVs may enhance the triggering of innate immune pathways, representing a therapeutic vulnerability in H3.3K27M HGGs.
2019-05-13 | GSE129136 | GEO