Project description:Gliomas bearing driver mutations of histone 3 lysine 27 (H3K27M) are incurable brain tumors. H3K27M mutant tumors display unique epigenomes with global loss of the chromatin repressive H3K27 trimethylation mark. Here, we generated a syngeneic H3K27M mouse model to study the dependence upon amino acid (AA) metabolism by performing an AA drop out screen. H3K27M mutant cells, but not histone wildtype cells, were highly dependent on the amino acid, methionine. Interrogating the methionine cycle dependency through an siRNA screen identified the enzyme Methionine Adenosyltransferase 2A (MAT2A), which catalyzes production of S-adenosylmethionine (SAM), a methyl donor. Sensitivity to MAT2A loss in H3K27M mutant cells was not mediated through the canonical mechanism of MTAP deletion; instead, H3K27M mutant cells have lower MAT2A protein levels, which is mediated by Adenosylmethionine Decarboxylase 1 (AMD1) production of decarboxylated SAM (dcSAM). MAT2A loss induces global depletion of H3K36me3, a potent chromatin mark of transcriptional elongation, as evaluated by quantitative chromatin immunoprecipitation with reference exogenous genome sequencing (ChIP-Rx-Seq) in multiple DIPG lines. Tandem H3K36me3 ChIP-Rx-seq and RNA-seq identified several oncogenic and developmental transcriptional programs associated with MAT2A loss. Moreover, inducible knockdown of MAT2A or methionine-restricted diets (MR) extended survival in both syngeneic and patient-derived xenograft models (PDXs) in vivo. Collectively, our results provide novel connections between AA metabolism and the epigenome in H3K27M gliomas, suggesting that MAT2A, a central regulator of methionine metabolism, presents exploitable therapeutic vulnerabilities in H3K27M gliomas.
Project description:We generated a syngeneic H3K27M diffuse midline glioma (DMG) mouse model and performed total RNA seq on H3K27MPP cells and control cell lines H3wtMPP and Normal Neural stem cells. Aditionally we generate a Dox Inducible Mat2A Knockdown in that human DIPG cell line DIPG04 and performed RNA sequencing on cells treated with 2ug/ml Doxycyclin and no treatment
Project description:The lysine-to-methionine mutation at residue 27 of histone H3 (H3K27M) is a driving mutation in Diffuse Intrinsic Pontine Glioma (DIPG), a highly aggressive form of pediatric brain tumor with no effective treatment and little chance of survival. H3K27M reshapes the epigenome through a global inhibition of PRC2 catalytic activity, displacement of methylation at lysine 27 of histone H3 (H3K27me2/3), and thus promoting oncogenesis of DIPG. As a consequence, a histone modification H3K36me2, antagonistic to H3K27me2/3, is aberrantly elevated. Here, we investigate the role of H3K36me2 in H3K27M-DIPG by tackling its upstream catalyzing enzymes (writers) and downstream binding factors (readers). We determine that NSD1 and NSD2 are the key writers for H3K36me2. Loss of NSD1/2 in H3K27M-DIPG impedes cellular proliferation in vitro and tumorigenesis in vivo, and disrupts tumor-promoting gene expression programs. Further, we demonstrate that LEDGF and HDGF2 are the main readers that mediate the pro-tumorigenic effects downstream of NSD1/2-H3K36me2. Treatment with a chemically modified peptide mimicking endogenous H3K36me2 dislodges LEDGF/HDGF2 from chromatin and specifically inhibits the proliferation of H3K27M-DIPG. Together, our results indicate a functional pathway of NSD1/2-H3K36me2-LEDGF/HDGF2 as an acquired dependency in H3K27M-DIPG and suggest a possibility to target this pathway for therapeutic interventions.
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.
Project description:RNAseq was used to identify host and viral transcriptome changes in methionine restricted Rael cells or Rael cells expressing control, AHCY or MAT2A sgRNAs.
Project description:Background: Targeting the metabolic dependencies of acute myeloid leukemia (AML) cells is a promising therapeutical strategy. In particular, the cysteine and methionine metabolism pathway (C/M) is significantly altered in AML cells compared to healthy blood cells. Moreover, methionine has been identified as one of the dominant amino acid dependencies of AML cells. Methods: Through RNA-seq, we found that the two nucleoside analogs 8-chloro-adenosine (8CA) and 8-amino-adenosine (8AA) significantly suppress the C/M pathway in AML cells, and methionine-adenosyltransferase-2A (MAT2A) is one of most significantly downregulated genes. Additionally, mass spectrometry analysis revealed that Venetoclax (VEN), a BCL-2 inhibitor recently approved by the FDA for AML treatment, significantly decreases the intracellular level of methionine in AML cells. Based on these findings, we hypothesized that combining 8CA or 8AA with VEN can efficiently target the Methionine-MAT2A-S-adenosyl-methionine (SAM) axis in AML. Results: Our results demonstrate that VEN and 8CA/8AA synergistically decrease the SAM biosynthesis and effectively target AML cells both in vivo and in vitro. Conclusions: These findings suggest the promising potential of combining 8CA/8AA and VEN for AML treatment by inhibiting Methionine-MAT2A-SAM axis and provide a strong rationale for our recently activated clinical trial.
Project description:Lysine 27 to methionine mutation (H3K27M) of the H3F3A gene, which encodes the variant histone H3.3, is found in the majority of Diffuse Intrinsic Pontine Gliomas (DIPGs). DIPGs are the most aggressive form of pediatric gliomas and have a median survival of <1 year from diagnosis. As H3K27M mutation is necessary but not sufficient to cause DIPGs, it is accompanied by several other mutations in tumors. However, the mechanisms by which H3K27M increases vulnerability to DIPG tumorigenesis, while expected to involve altered epigenetic regulation is unclear. Thus, in this work we built pairs of isogenic human embryonic stem cell lines with versus without this mutation, in the absence of other DIPG contributory mutations, to investigate mechanisms by which H3K27M mutation could affect cellular proliferation and differentiation and how these were related to alterations in the transcriptome, H3K27me3, and the DNA methylome. We found that H3K27M increased stem cell proliferation and interfered with differentiation, resulting in loss of most H3K27me3 and resulting in anomalous onset of expression of developmental genes during multilineage or directed differentiation. This work suggests mechanisms by which H3K27M mutation influences stem cell properties, contributing to DIPG tumorigenesis.
Project description:Lysine 27 to methionine mutation (H3K27M) of the H3F3A gene, which encodes the variant histone H3.3, is found in the majority of Diffuse Intrinsic Pontine Gliomas (DIPGs). DIPGs are the most aggressive form of pediatric gliomas and have a median survival of <1 year from diagnosis. As H3K27M mutation is necessary but not sufficient to cause DIPGs, it is accompanied by several other mutations in tumors. However, the mechanisms by which H3K27M increases vulnerability to DIPG tumorigenesis, while expected to involve altered epigenetic regulation is unclear. Thus, in this work we built pairs of isogenic human embryonic stem cell lines with versus without this mutation, in the absence of other DIPG contributory mutations, to investigate mechanisms by which H3K27M mutation could affect cellular proliferation and differentiation and how these were related to alterations in the transcriptome, H3K27me3, and the DNA methylome. We found that H3K27M increased stem cell proliferation and interfered with differentiation, resulting in loss of most H3K27me3 and resulting in anomalous onset of expression of developmental genes during multilineage or directed differentiation. This work suggests mechanisms by which H3K27M mutation influences stem cell properties, contributing to DIPG tumorigenesis.