Reciprocal gene editing defines targetable mutant H3.3 oncohistone effectors in pediatric glioma
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA532652 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR8892220_1.fastq.gz | Fastqsanger.gz | |||
| SRR8892220_2.fastq.gz | Fastqsanger.gz | |||
| SRR8892230_1.fastq.gz | Fastqsanger.gz | |||
| SRR8892230_2.fastq.gz | Fastqsanger.gz | |||
| SRR8899900_1.fastq.gz | Fastqsanger.gz |
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Project description:High-grade pediatric gliomas often contain histone H3.3 mutations, but open questions remain about oncogenic mechanisms. To address this gap, we performed ‘reciprocal gene editing’ using CRISPR-Cas9 to introduce H3.3 mutations (K27M, G34R) into H3.3-wildtype brain and glioma cells, while in parallel reverting pre-existing K27M mutations in glioma cells back to wildtype. Analyses of our reciprocally-edited cells indicate that H3.3 mutation leads to specific transcriptomic and epigenetic events, and associated cell biological changes including in xenograft assays. We used these data and the reciprocally-edited cells to screen selected drugs and identify specific putative treatments that are mutant H3.3-specific. Overall, reciprocal gene editing provides new insights into mutant H3.3 oncogenic mechanisms and more broadly may prove useful for studying other cancer-associated mutations.
2020-06-29 | GSE129765 | GEO
Project description:The H3K27M oncogenic histone (oncohistone) mutation drives ~80% of incurable childhood brain tumors known as diffuse midline gliomas (DMGs). The major molecular feature of H3K27M mutant DMGs is a global loss of H3K27 tri-methylation (H3K27me3), a phenotype conserved in Caenorhabditis elegans (C. elegans). Here we perform unbiased genome-wide suppressor screens in C. elegans expressing H3K27M, and isolate 20 suppressors, all of which at least partially restore H3K27me3. 19/20 suppressor mutations map to the same histone H3.3 gene in which the K27M mutation was originally introduced. Most of these create single amino acid substitutions between residues R26-Y54, which do not disrupt oncohistone expression. Rather, they are predicted to impair interactions with the Polycomb Repressive Complex 2 (PRC2) and are functionally conserved in human cells. Further, we mapped a single extragenic H3K27M suppressor to ubc-20, an E2 ubiquitin conjugating enzyme, whose loss rescued H3K27me3 to nearly 50% wild-type levels despite continued oncohistone expression and chromatin incorporation. We demonstrate that ubc-20 is the major enzyme responsible for generating di-ubiquitinated histone H2B. Our study provides in vivo support for existing models of PRC2 inhibition via direct oncohistone contact, and suggests that the effects of H3K27M may be modulated by H2B ubiquitination.
2024-11-20 | GSE275118 | GEO
Project description:Point mutations within the histone H3.3 are frequent in aggressive childhood brain tumours known as paediatric high-grade gliomas (pHGGs). Intriguingly, different mutations arise in discrete anatomical regions: H3.3-G34R within the forebrain and H3.3-K27M preferentially within the hindbrain. The reasons for this contrasting aetiology are unknown. By engineering human foetal neural stem cell cultures from distinct regions, we demonstrate here that cell-intrinsic regional identity provides differential responsiveness to each mutant that mirrors the origins of pHGGs. Focusing on H3.3-G34R, we find that the oncohistone supports proliferation of forebrain cells, while inducing a cytostatic response in the hindbrain. Mechanistically, H3.3-G34R does not impose widespread transcriptional or epigenetic changes, but impairs recruitment of ZMYND11, a transcriptional repressor of highly expressed genes. We therefore propose that H3.3-G34R promotes tumorigenesis by stabilising the expression of key progenitor genes and, thus, locking initiating forebrain cells into their preexisting immature state.
2021-03-24 | GSE163185 | GEO
Project description:Point mutations within the histone H3.3 are frequent in aggressive childhood brain tumours known as paediatric high-grade gliomas (pHGGs). Intriguingly, different mutations arise in discrete anatomical regions: H3.3-G34R within the forebrain and H3.3-K27M preferentially within the hindbrain. The reasons for this contrasting aetiology are unknown. By engineering human foetal neural stem cell cultures from distinct regions, we demonstrate here that cell-intrinsic regional identity provides differential responsiveness to each mutant that mirrors the origins of pHGGs. Focusing on H3.3-G34R, we find that the oncohistone supports proliferation of forebrain cells, while inducing a cytostatic response in the hindbrain. Mechanistically, H3.3-G34R does not impose widespread transcriptional or epigenetic changes, but impairs recruitment of ZMYND11, a transcriptional repressor of highly expressed genes. We therefore propose that H3.3-G34R promotes tumorigenesis by stabilising the expression of key progenitor genes and, thus, locking initiating forebrain cells into their preexisting immature state.
2021-03-24 | GSE163044 | GEO
Project description:Development proceeds by the activation of genes by transcription factors and the inactivation of others by chromatin-mediated gene silencing. In some cases development can be reversed or redirected by mis-expression of master regulator transcription factors. This must involve the activation of previously silenced genes, and such developmental aberrations are thought to underlie a variety of cancers. Here, we express the wing-specific Vestigial master regulator to reprogram the developing eye, and test the role of silencing in reprogramming using an H3.3K27M oncohistone mutation that dominantly inhibits histone H3K27 trimethylation. We find that expression of the oncohistone blocks eye-to-wing reprogramming. CUT&Tag chromatin profiling of mutant tissues shows that H3K27me3 domains are globally reduced with oncohistone expression, suggesting that previous developmental programs must be silenced for effective transformation. Strikingly, mis-expressed Vg and H3.3K27M synergize to stimulate overgrowth of eye tissue, a phenotype that resembles that of mutations in Polycomb Repressive Complex 1 components. Our results imply that growth dysregulation can result from the simple combination of crippled silencing and transcription factor mis-expression, an effect that may explain the origins of oncohistone-bearing cancers.
2021-06-15 | GSE161919 | GEO
Project description:Oncohistone mutations are crucial drivers for tumorigenesis, but how a living organism responds to and governs the loss-of-function oncohistone remains unclear. Here, we generated a histone H2B triple knockout (3KO) strain in Caenorhabditis elegans, which decreased the embryonic H2B level, disrupted cell divisions, and caused animal sterility. Our genetic screens identified mutations defective in a histone H3-H4 chaperone UNC-85 as suppressors that recovered H2B 3KO fertility. We found that unc-85 mutations reduced chromatin H3-H4 levels and that inhibiting other H3-H4 chaperones or H3-H4 histones also rescued H2B 3KO sterility. The oncohistone H2BE76K mutation disrupts the H2B-H4 interface and causes nucleosome instability, and we showed that blocking H3-H4 chaperones restored cell division defects in C. elegans or human cells carrying H2BE76K. Thus, our results indicate that reducing chromatin H3-H4 rescues H2B loss and suggest that inhibiting H3-H4 chaperones may be a therapeutic strategy to treat cancers resulting from loss-of-function H2B oncohistone.
2022-04-03 | GSE185582 | GEO
Project description:Histone variants can effect nucleosome stability or affect histone of DNA modifications. H3.3 is a major H3 histone variant that is incorporated into chromatin outside of S-phase in various eukaryotes. In animals, H3.3 is associated with active transcription and possibly maintenance of transcriptional memory. Plant H3.3, which evolved independently of animal H3.3, is much less well understood. We performed ChIP-chip using chromatin from rosette leaves of 35S:H3.3-YFP plants.
2014-03-10 | E-MTAB-1685 | biostudies-arrayexpress
Project description:Histone H3.3 is frequently mutated in cancers, with the lysine 36 to methionine mutation (K36M) being a hallmark of chondroblastomas. While it is known that H3.3K36M changes the cellular epigenetic landscape, it remains unclear how it affects the dynamics of gene expression. Here, we use a synthetic reporter to measure the effect of H3.3K36M on silencing and epigenetic memory after recruitment of KRAB: a member of the largest class of human repressors, commonly used in synthetic biology, and associated with H3K9me3. We find that H3.3K36M, which decreases H3K36 methylation, leads to a decrease in epigenetic memory and promoter methylation weeks after KRAB release. We propose a new model for establishment and maintenance of epigenetic memory, where H3K36 methylation is necessary to convert H3K9me3 domains into DNA methylation for stable epigenetic memory. Our quantitative model can inform oncogenic mechanisms and guide development of epigenetic editing tools.
| S-EPMC10592807 | biostudies-literature
Project description:Histone H3.3 is a highly conserved histone H3 replacement variant in metazoans, and has been implicated in many important biological processes including cell differentiation and reprogramming. Germline and somatic mutations in H3.3 genomic incorporation pathway components, or in H3.3 encoding genes, have been associated with human congenital diseases and cancers, respectively. However, the role of H3.3 in mammalian development remains unclear. To address this question, we generated H3.3 null mouse models through classical genetic approaches. We found H3.3 plays an essential role in mouse development. Complete depletion of H3.3 leads to developmental retardation and early embryonic lethality. At the cellular level, H3.3 loss triggers cell cycle suppression and cell death. Surprisingly, H3.3 depletion does not dramatically disrupt gene regulation in the developing embryo. Instead, H3.3 depletion causes dysfunction of heterochromatin structures at telomeres, centromeres and pericentromeric regions of chromosomes leading to mitotic defects. The resulting karyotypical abnormalities and DNA damage lead to p53 pathway activation. In summary, our results reveal that an important function of H3.3 is to support chromosomal heterochromatic structures, thus maintaining genome integrity during mammalian development. RNA-seq in embryos at E10.5 comparing 3 samples with the following genotype Trp53-/-; H3f3afl/-; H3f3bfl/-; Sox2-CreTg/0 to three samples with the following genotype Trp53-/-; H3f3afl/+; H3f3bfl/+; Sox2-CreTg/0
2015-06-12 | E-GEOD-69771 | biostudies-arrayexpress
Project description:The H3.3K27M oncohistone antagonizes reprogramming in Drosophila
| PRJNA679825 | ENA