Project description:Previously, we suggested a cytosolic role for the histone-methyltransferase Ezh2 in regulating lymphocyte activation, but molecular mechanisms underpinning this extra-nuclear function remained unclear. Here we show that Ezh2 regulates integrin-signaling and adhesion dynamics of neutrophils and dendritic cells. Ezh2 deficiency impaired integrin-dependent transendothelial migration of innate leukocytes and restricted disease progression in an animal model of multiple sclerosis. Direct methylation of talin, a key regulatory molecule in cell migration, by Ezh2 disrupted talin binding to F-actin and thereby promoted adhesion structure turnover. This regulatory effect was abolished by targeted disruption of Ezh2 interactions with Vav1. Our studies reveal a novel extra-nuclear function for Ezh2 in regulating adhesion dynamics with implications for leukocyte migration, immune responses and potentially pathogenic processes. Control and Ezh2-deficient bone marrow derived immature and mature dendritic cells were analyzed in triplicates
Project description:Previously, we suggested a cytosolic role for the histone-methyltransferase Ezh2 in regulating lymphocyte activation, but molecular mechanisms underpinning this extra-nuclear function remained unclear. Here we show that Ezh2 regulates integrin-signaling and adhesion dynamics of neutrophils and dendritic cells. Ezh2 deficiency impaired integrin-dependent transendothelial migration of innate leukocytes and restricted disease progression in an animal model of multiple sclerosis. Direct methylation of talin, a key regulatory molecule in cell migration, by Ezh2 disrupted talin binding to F-actin and thereby promoted adhesion structure turnover. This regulatory effect was abolished by targeted disruption of Ezh2 interactions with Vav1. Our studies reveal a novel extra-nuclear function for Ezh2 in regulating adhesion dynamics with implications for leukocyte migration, immune responses and potentially pathogenic processes.
Project description:Ovarian cancer develops early intra-peritoneal metastasis establishing a pro-tumorigenic tumor microenvironment (TME) through reprogramming normal mesenchymal stem cells into carcinoma-associated mesenchymal stem cells (CA-MSCs). CA-MSCs are the stromal stem cell of the TME, supporting cancer growth, increasing desmoplasia, angiogenesis and chemotherapy resistance. We demonstrate epigenetic rewiring drives CA-MSC formation via enhancer-enriched DNA hypermethylation, altered chromatin accessibility and differential histone modifications inducing a partial mesenchymal to epithelial transition (MET) increasing tumor cell adhesion. Direct CA-MSC:tumor cell interactions, confirmed in patient ascites, facilitate ovarian cancer metastasis through co-migration. WT1, a developmental mediator of MET, and EZH2, mediate CA-MSC epigenetic reprogramming. WT1 overexpression induces CA-MSC conversion while WT1 knock-down, in combination with EZH2 inhibition, blocks CA-MSC formation. EZH2 inhibition subsequently decreases intra-abdominal metastasis.
Project description:In eukaryotes, epigenetic post-translational modification of histones is critical for regulation of chromatin structure and gene expression. EZH2 is the catalytic subunit of the Polycomb Repressive Complex 2 (PRC2) and is responsible for repressing target gene expression through methylation of histone H3 on lysine 27 (H3K27). Over-expression of EZH2 is implicated in tumorigenesis and correlates with poor prognosis in multiple tumor types. Recent reports have identified somatic heterozygous mutations of Y641 and A677 residues within the catalytic SET domain of EZH2 in diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL). The Y641 residue is the most frequently mutated residue, with 22% of GCB (Germinal centre B-cell) DLBCL and FL harboring mutations at this site. These lymphomas exhibit increased H3K27 tri-methylation (H3K27me3) due to altered substrate preferences of the mutant enzymes. However, it is unknown whether direct inhibition of EZH2 methyltransferase activity alone will be effective in treating lymphomas carrying activating EZH2 mutations. Herein, we demonstrate that GSK126, a potent, highly-selective, SAM-competitive, small molecule inhibitor of EZH2 methyltransferase activity, decreases global H3K27me3 levels and reactivates silenced PRC2 target genes. GSK126 effectively inhibits the proliferation of EZH2 mutant DLBCL cell lines and dramatically inhibits the growth of EZH2 mutant DLBCL xenografts in mice. Together, these data demonstrate that pharmacological inhibition of EZH2 activity may provide a promising treatment for EZH2 mutant lymphoma. We performed a ChIP-seq experiment to understand the genomewide pattern of H3K27me3 enrichment in DLBCL cell lines that were differentially sensitive to GSK126. H3K27me3 bound chromatin and input controls was immunoprecipitated and subjected to sequencing on the Illumina GA Iix. In total, 3 cell lines were profiled - 3 EZH2 mutant (Pfeiffer, KARPAS-422, WSU-DLCL2).
Project description:Abnormalities of chromosome 7q are common in myeloid malignancies. Agilent CGH arrays targeted to 7q and Affymetrix SNP 6.0 arrays were used to characterise 7q aUPD and deletions. Sample #017 in this data series showed a microdeletion encompassing EZH2. Screening of a total of 614 cases with myeloid disorders revealed 49 monoallelic or biallelic EZH2 mutations in 42 individuals, most commonly myelodysplastic/myeloproliferative neoplasms (27/219; 12%) and myelofibrosis (4/30; 13%). EZH2 encodes the catalytic subunit of the Polycomb repressive complex 2 (PRC2), the highly conserved histone H3 lysine 27 methyltransferase that influences stem cell renewal by epigenetic repression of genes involved in cell fate decisions. EZH2 has oncogenic activity and its overexpression has been causally linked to differentiation blocks in epithelial tumors. Unexpectedly, the mutations we identified resulted in premature chain termination or direct abrogation of histone methyltransferase activity, suggesting that EZH2 acts as a tumor suppressor for myeloid malignancies. High density CGH array analysis of 7q and the TET2 region in 8 atypical myeloproliferative neoplasms
Project description:This SuperSeries is composed of the following subset Series: GSE41651: Characterization of the EZH2-MMSET histone methyltransferase regulatory axis in cancer [expression] GSE41652: Characterization of the EZH2-MMSET histone methyltransferase regulatory axis in cancer [ChIP-seq] Refer to individual Series
Project description:Chemotherapy resistance is the main impediment in the treatment of acute myeloid leukaemia (AML). Despite rapid advances, the various mechanisms that lead to resistance development remain to be defined in detail. Here we report that loss-of-function mutations (LOF) in the histone methyltransferase EZH2 have the potential to confer resistance against the chemotherapeutic agent cytarabine. We identify seven distinct EZH2 mutations leading to loss of H3K27 trimethylation via multiple mechanisms. Analysis of matched diagnosis and relapse samples reveal a heterogenous regulation of EZH2 and a loss of EZH2 in 50% of patients. We confirm that loss of EZH2 induces resistance against cytarabine in the cell lines HEK293T and K562 as well as in a patient-derived xenograft (PDX) model. Proteomics and transcriptomics analysis reveal that resistance is conferred by upregulation of multiple direct and indirect EZH2 target genes that are involved in apoptosis evasion, augmentation of proliferation and alteration of transmembrane transporter function. Our data indicates, that loss of EZH2 results in upregulation of its target genes, providing the cell with a selective growth advantage, which mediates chemotherapy resistance.
Project description:Inhibition of H3K27 methyltransferase EZH2 enhances osteogenic commitment of human mesenchymal progenitors and Ezh2 inactivation in mouse calvarial cells induces a post-proliferative state concomitant with increased production of a bone-related mineralizing extra-cellular matrix.
Project description:We studied transcriptional changes by Affymetrix human microarrays in 2 DLBCL cell lines as a result of shRNA mediated knockdown of EZH2. In eukaryotes, epigenetic post-translational modification of histones is critical for regulation of chromatin structure and gene expression. EZH2 is the catalytic subunit of the Polycomb Repressive Complex 2 (PRC2) and is responsible for repressing target gene expression through methylation of histone H3 on lysine 27 (H3K27). Over-expression of EZH2 is implicated in tumorigenesis and correlates with poor prognosis in multiple tumor types. Recent reports have identified somatic heterozygous mutations of Y641 and A677 residues within the catalytic SET domain of EZH2 in diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL). The Y641 residue is the most frequently mutated residue, with 22% of GCB (Germinal Cell B-cell) DLBCL and FL harboring mutations at this site. These lymphomas exhibit increased H3K27 tri-methylation (H3K27me3) due to altered substrate preferences of the mutant enzymes. However, it is unknown whether direct inhibition of EZH2 methyltransferase activity alone will be effective in treating lymphomas carrying activating EZH2 mutations. Herein, we demonstrate that GSK126, a potent, highly-selective, SAM-competitive, small molecule inhibitor of EZH2 methyltransferase activity, decreases global H3K27me3 levels and reactivates silenced PRC2 target genes. GSK126 effectively inhibits the proliferation of EZH2 mutant DLBCL cell lines and dramatically inhibits the growth of EZH2 mutant DLBCL xenografts in mice. Together, these data demonstrate that pharmacological inhibition of EZH2 activity may provide a promising treatment for EZH2 mutant lymphoma. Pfeiffer and KARPAS-422 cells were treated with either shRNA targeting EZH2 (shEZH2) or a non targeting control (shNTC) for 10 days.
Project description:This SuperSeries is composed of the following subset Series: GSE30971: The Histone Methyltransferase Wbp7 Controls Macrophage Function through GPI Glycolipid Anchor Synthesis. [Expression Profile] GSE30972: The Histone Methyltransferase Wbp7 Controls Macrophage Function through GPI Glycolipid Anchor Synthesis. [ChIP_seq] Refer to individual Series