Polycomb Ezh2 controls the fate of GABAergic neurons in the embryonic cerebellum
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ABSTRACT: Genetic ablation of Ezh2 in Pax7-Cre driven lineages resulted in developmental defects in E13.5 cerebellum. The transcriptional change and H3K27me3 mark change were investigated by RNA-seq and ChIP-seq on H3K27me3.
Project description:Although the genetic interactions between signaling pathways and transcription factors have been largely decoded, much remains to be learned about the epigenetic regulation of cerebellar development. Here, we report that cerebellar deletion of Ezh2, the methyltransferase subunit of the PRC2 complex, results in reduced H3K27me3 and profound transcriptional dysregulation, including that of a set of transcription factors directly involved in cerebellar neuronal cell-type specification and differentiation. Such transcriptional changes lead to increased GABAergic interneurons and decreased Purkinje cells. Transcriptional changes also inhibit the proliferation of granule precursor cells derived from the rhombic lip. The loss of both cell types ultimately results in cerebellar hypoplasia. These findings indicate Ezh2/PRC2 plays crucial roles in regulating neurogenesis from both cerebellar germinal zones.
Project description:Overexpression of EZH2 in estrogen receptor negative (ER-) breast cancer promotes metastasis. EZH2 has been mainly studied as the catalytic component of the Polycomb Repressive Complex 2 (PRC2) that mediates gene repression by trimethylating histone H3 at lysine 27 (H3K27me3). However, how EZH2 drives metastasis despite the low H3K27me3 levels observed in ER- breast cancer is unknown. We have shown that in human invasive carcinomas and distant metastases, cytoplasmic EZH2 phosphorylated at T367 is significantly associated with ER- disease and low H3K27me3 levels. Here, we explore the interactome of EZH2 and of a phosphodeficient mutant EZH2_T367A. We identified novel interactors of EZH2, and identified interactions that are dependent on the phosphorylation and cellular localization of EZH2 that may play a role in EZH2 dependent metastatic progression.
Project description:Background: Precise spatiotemporal control of gene expression is essential for the establishment of correct cell numbers and identities during brain development. This process involves epigenetic control mechanisms, such as those mediated by the polycomb group protein Ezh2 that catalyzes trimethylation of histone H3K27 (H3K27me3) and thereby represses gene expression. Results: Here we show that Ezh2 plays a crucial role in development and maintenance of the midbrain. Conditional deletion of Ezh2 in the developing midbrain resulted in decreased neural progenitor proliferation, which is associated with derepression of cell cycle inhibitors and negative regulation of Wnt/beta-catenin signaling. Of note, Ezh2 ablation also promoted ectopic expression of a forebrain transcriptional program involving derepression of the forebrain determinants Foxg1 and Pax6. This was accompanied by reduced expression of midbrain markers, including Pax3 and Pax7, as a consequence of decreased Wnt/beta-catenin signaling. Conclusion: Ezh2 is required for appropriate brain growth and for maintenance of regional identity by H3K27me3-mediated gene repression and control of canonical Wnt signaling. After tissue isolation from dorsal midbrains of embryonic day (E) 10.5 embryos, total RNA was isolated with the RNAeasy kit (Qiagen) and RNase-Free DNase Set (79254, Qiagen) following the manufacturer's instructions. Isolated total RNA of E10.5 control (n=3, from 2 different litters) and Ezh2 cko (n=3, from 2 different litters) dorsal midbrains was used for microarray analysis performed at the Functional Genomics Center Zurich (FGCZ), Switzerland, using the Affymetrix A430 platform.
Project description:We hypothesized that EZH2 could be involved in immune escape in Merkel Cell Carcinoma (MCC). In this context, we aimed at evaluating whether EZH2 might contribute to HLA-I expression repression in MCC. To this purpose, we first investigated whether low/lack of HLA-I expression is associated with high H3K27me3 levels in MCC tumor samples. Whole proteome analysis of the PeTa cell line by mass spectrometry after DZNeP treatment (EZH2 inhibitor) revealed upregulation of proteins involved in Fc receptor, as well as antigen processing and presentation pathways components.
Project description:The symptoms of ataxia-telangiectasia (A-T) include a progressive neurodegeneration caused by ATM protein deficiency. We previously found that nuclear accumulation of histone deacetylase-4, HDAC4, contributes to this degeneration; we now report that increased histone H3K27 trimethylation (H3K27me3) mediated by polycomb repressive complex 2 (PRC2) also plays an important role in the A-T phenotype. Enhancer of zeste homolog 2 (EZH2), a core catalytic component of PRC2, is identified as a new ATM kinase target, and its S734 phosphorylation reduces protein stability. Thus, PRC2 formation is elevated along with H3K27me3in ATM deficiency. ChIP-sequencing shows a significant increase in H3K27me3 ‘marks’ and a dramatic shift in their location. The change of H3K27me3 chromatin-binding pattern is directly related to cell cycle re-entry and cell death of ATM-deficient neurons. Lentiviral knockdown of EZH2 rescues Purkinje cell degeneration and behavioral abnormalities in Atm / mice, demonstrating that EZH2-mediated H3K27me3 is another key factor in A-T neurodegeneration. Two samples each were run of brain total RNA from Atm+/+ and Atm-/- mice.
Project description:Background: Precise spatiotemporal control of gene expression is essential for the establishment of correct cell numbers and identities during brain development. This process involves epigenetic control mechanisms, such as those mediated by the polycomb group protein Ezh2 that catalyzes trimethylation of histone H3K27 (H3K27me3) and thereby represses gene expression. Results: Here we show that Ezh2 plays a crucial role in development and maintenance of the midbrain. Conditional deletion of Ezh2 in the developing midbrain resulted in decreased neural progenitor proliferation, which is associated with derepression of cell cycle inhibitors and negative regulation of Wnt/β-catenin signaling. Of note, Ezh2 ablation also promoted ectopic expression of a forebrain transcriptional program involving derepression of the forebrain determinants Foxg1 and Pax6. This was accompanied by reduced expression of midbrain markers, including Pax3 and Pax7, as a consequence of decreased Wnt/β-catenin signaling. Conclusion: Ezh2 is required for appropriate brain growth and for maintenance of regional identity by H3K27me3-mediated gene repression and control of canonical Wnt signaling.
Project description:The Enhancer of Zeste 2 Polycomb Repressive Complex 2 Subunit (EZH2) is an essential epigenetic modifier able to methylate lysine 27 on histone H3 (H3K27) to induce chromatin compaction, protein complex recruitment and ultimately transcriptional repression. Hematologic malignancies, including Diffuse Large B cell lymphoma (DLBCL) and Acute myeloid leukemia (AML) have shown a high EZH2-mutation frequency (>20%) associated with poor clinical outcomes. Particularly, two distinct oncogenic mutations, so-called gain-of-function (Y641F and A677G) and loss-of-function (H689A and F667I) are found in the catalytic domain of EZH2. In this study, a comprehensive multi-omics approach was employed to characterize downstream effects of H3K27me3 deposition driven by EZH2 mutations. Human embryonic kidney cells (HEK293T) were transfected to generate three stable EZH2 mutants: EZH2(Y641F), EZH2(A677G), and EZH2(H689A/F667I), which were validated via immunoblotting and DIA-MS-based histone profiling assay. Subsequently, constructs were analyzed under a comprehensive multi-omics approach including label-free whole-cell proteomics, acquired with a Bruker timsTOF Pro HPLC-MS/MS with Ion Mobility. Important protein interactors at nuclear level were dysregulated, such as SMYD3 (SET and MYND domain containing 3), NSD2 (nuclear receptor binding SET domain protein 2) and CHD7 (chromodomain helicase DNA binding protein 7), suggesting a cooperative network of chromatin remodelers for gene expression reprogramming.
Project description:The EZH2 histone methyltransferase mediates the humoral immune response and drives lymphomagenesis through de novo formation of bivalent chromatin domains at critical germinal center (GC) B cell promoters. Herein we show that the actions EZH2 in driving GC formation and lymphoma precursor lesions are dependent on the presence of the BCL6 transcriptional repressor, both of which are in turn dependent on the presence of non-canonical PRC1-BCOR complex. BCL6-BCOR complexes assemble preferentially at bivalent promoters in an H3K27me3-dependent manner. We observe specific induction of the CBX8 chromodomain protein in GC B cells. CBX8 binds to H3K27me3 at bivalent promoters and is required for stable association of BCOR complex and its histone modifications. CBX8 loss of function in B cells phenocopies loss of EZH2 and H3K27me3. Moreover, oncogenic BCL6 and EZH2 cooperate to accelerate diffuse large B cell lymphoma (DLBCL) development and combinatorial targeting of these repressors results in enhanced anti-lymphoma activity in vitro, in vivo and in primary human DLBCLs. KDM2B ChIP-sequencing of OCI-Ly1 cells
Project description:The Enhancer of Zeste 2 Polycomb Repressive Complex 2 Subunit (EZH2) is an essential epigenetic modifier able to methylate lysine 27 on histone H3 (H3K27) to induce chromatin compaction, protein complex recruitment and ultimately transcriptional repression. Hematologic malignancies, including Diffuse Large B cell lymphoma (DLBCL) and Acute myeloid leukemia (AML) have shown a high EZH2-mutation frequency (>20%) associated with poor clinical outcomes. Particularly, two distinct oncogenic mutations, so-called gain-of-function (Y641F and A677G) and loss-of-function (H689A and F667I) are found in the catalytic domain of EZH2. In this study, a comprehensive multi-omics approach was employed to characterize downstream effects of H3K27me3 deposition driven by EZH2 mutations. Human embryonic kidney cells (HEK293T) were transfected to generate three stable EZH2 mutants: EZH2(Y641F), EZH2(A677G), and EZH2(H689A/F667I), which were validated via immunoblotting and DIA-MS-based histone profiling assay. The histone profiling assay demonstrated a significant increase of approximately two-fold in H3.1/H3.3K27me3 for Y641F EZH2 mutant. There was a modest increase in the combinatorial PTMs H3.1/H3.3K27me3K36me1 and a significant depletion in H3.1 and H3.3 K27me2. The most depleted peptide was H3.3K27me2K36me2. For the A677G EZH2 mutant, the assay demonstrated an enrichment on H3.1/H3.3K27me3, combinatorial K27me3K36me1 and a slight increase in K27me1 and K18ac but only on H3.1. The most depleted peptide was H3.3K27me2K36me2. The H689A/F667I cell line has the most alterations in global histone PTMs. The most highly enriched were H3.1/H3.3K36me2, H3.1K9me3 and H3.3K36me1. The most depleted modifications were H3.1K23ac and H3.1K27me3.
Project description:This SuperSeries is composed of the following subset Series: GSE40970: ChIP-seq analysis of H3K27me3 histone modification in EZH2 mutant and wild type DLBCL cell lines GSE40971: Gene expression profiling of EZH2 mutant and wild type DLBCL cell lines treated with EZH2 inhibitor GSE41239: Gene expression profiling of two DLBCL cell lines upon shRNA mediated knockdown of EZH2 Refer to individual Series