Project description:Trimethylation on H3K27 (H3K27me3) mediated by Polycomb repressive complex 2 (PRC2) has been linked to embryonic stem cell (ESC) identity and pluripotency. EZH2, the catalytic subunit of PRC2, has been reported as the sole histone methyltransferase that methylates H3K27 and mediates transcriptional silencing. Analysis of Ezh2(-/-) ESCs suggests existence of an additional enzyme(s) catalyzing H3K27 methylation. We have identified EZH1, a homolog of EZH2 that is physically present in a noncanonical PRC2 complex, as an H3K27 methyltransferase in vivo and in vitro. EZH1 colocalizes with the H3K27me3 mark on chromatin and preferentially preserves this mark on development-related genes in Ezh2(-/-) ESCs. Depletion of Ezh1 in cells lacking Ezh2 abolishes residual methylation on H3K27 and derepresses H3K27me3 target genes, demonstrating a role of EZH1 in safeguarding ESC identity. Ezh1 partially complements Ezh2 in executing pluripotency during ESC differentiation, suggesting that cell-fate transitions require epigenetic specificity.
Project description:We found that both EZH1 and EZH2 contributes to cell growth and H3K27 methylation, and EZH1/2 dual inhibitors induce growth inhibition in malignant rhabdoid tumor (MRT). To investigate the molecular mechanism underlying the growth inhibition of EZH inhibitors in MRT cells, we performed RNA-sequencing analysis and compared differentially expressed genes between A204.1 cells treated with EZH1/2 dual inhibitor DS-3201b or EZH2 selective inhibitor EPZ-6438.
Project description:Multiple myeloma (MM) cell line treated with an inhibitor to EZH2/EZH1 (UNC1999), DNA methylation inhibitor (5-azacytidine), and a combination of both.
Project description:Establishment and differentiation of mammary alveoli during pregnancy are controlled by prolactin through the transcription factor STAT5. As pregnancy progresses mammary signature genes are activated in a defined temporal order, which coincides with the recruitment of STAT5 to respective regulatory sequences. This study addressed the question whether the methyltransferase and transcriptional co-activator EZH2 controls the differentiation clock of mammary epithelium. Ablation of Ezh2 from mammary stem cells resulted in precocious differentiation of alveolar epithelium and accelerated activation of mammary signature genes. This coincided with enhanced occupancy by EZH1, Pol II and STAT5 to mammary-specific loci. Notably, loss of EZH2 did not result in overt changes in genome-wide and gene-specific H3K27me3 patterns, suggesting that enhanced EZH1 recruitment can compensate for the loss of EZH2. However, differentiated mammary epithelia failed to form in the combined absence of EZH1 and EZH2. Transplantation experiments failed to demonstrate a role for EZH2 in the biology of mammary stem and progenitor cells. In summary, while EZH1 and EZH2 serve redundant functions in the establishment of H3K27me3 and formation of mammary alveoli, the presence of EZH2 is required to obtain controlled temporal differentiation of mammary epithelium. ChIP-seq EZH1, EZH2, PolIII; WT and E2KO mammary cells
Project description:Polycomb Repressive Complex 2 (PRC2) plays crucial roles in transcriptional regulation and stem cell development. However, the context-specific functions associated with alternative subunits remain largely unexplored. Here we show that the related enzymatic subunits EZH1 and EZH2 undergo an expression switch during hematopoiesis. We examine the in vivo stoichiometry of the PRC2 complexes by quantitative proteomics and reveal the existence of an EZH1-SUZ12 sub-complex lacking EED. We provide evidence that EZH1 together with SUZ12 form a non-canonical PRC2 complex, occupy active chromatin domains in the absence of H3K27me3, and positively regulate gene expression. Loss of EZH2 expression leads to global repositioning of EZH1 chromatin occupancy to EZH2 targets. Moreover, we demonstrate that an erythroid-specific enhancer mediates transcriptional activation of EZH1, and a switch from GATA2 to GATA1 controls the developmental EZH1/2 switch by differential association with EZH1 enhancers during erythropoiesis. Thus, the lineage- and developmental stage-specific regulation of PRC2 expression and subunit composition leads to a switch from canonical silencing to non-canonical PRC2 functions during blood stem cell specification. Analysis of genomic occupancy of EZH1, EZH2, EED, SUZ12, various histone marks and transcription factors in primary human fetal liver proerythroblasts by ChIP-seq. Sample GSM970262 was used as the input DNA sample.
Project description:Ezh2 and EZH1 are histone H3 lysine 27 (H3K27)-specific methyltransferases. Their hyperactive mutations and overexpression were found in cancer including various hematological malignancies. UNC1999 is a highly selective inhibitor for both enzymes. It suppresses H3K27 tri- and di-methylation globally and inhibits growth of MLL-rearranged acute leukemia. Here we performed ChIP-Seq to profile how UNC1999 affects distribution of H3K27me3 and its antagonizing H3K27ac in MLL-AF9-immortalized leukemia cells. We also performed ChIP-seq of SUZ12, an essential common cofactor of EZH2 and EZH1 following compound treatments. We treated MLL-AF9 transformed murine leukemia cells with DMSO, UNC1999 or UNC2400 (an inactive analog compound of UNC1999). Cells were then collected and used for ChIP-Sequencing of Input, H3K27me3, SUZ12, and H3K27ac.
Project description:Polycomb repressive complex 2 (PRC2) represses transcription by trimethylation of histone H3 at lysine 27. Valemetostat is a potent inhibitor of enhancer of zeste homolog (EZH)2 and EZH1, which are histone methyltransferases of PRC2. PRC2 inhibitors, including valemetostat, have been showing promises in multiple cancer types. PRC2 inhibitors, however, can induce thrombocytopenia as a class adverse effect. To better understand valemetostat-induced thrombocytopenia, we performed single-cell ATAC-seq and bulk RNA-seq for human bone marrow CD34+ cells that were in vitro differentiated into megakaryocytes.
Project description:Polycomb group (PcG) proteins initiate the formation of repressed chromatin domains and regulate developmental gene expression. A mammalian PcG protein, Enhancer of Zeste homolog 2 (Ezh2), triggers transcriptional repression by catalyzing the addition of methyl groups onto lysine-27 of histone H3 (H3K27me2/3)1. This action facilitates the binding of other PcG proteins to histone H3 and compaction of chromatin. Interestingly, there exists a paralog of Ezh2, termed Ezh1, whose primary function remains unclear. Here, we provide evidence for genome-wide association of Ezh1 with active epigenetic marks, RNA polymerase II (PolII) and mRNA production. Ezh1 depletion reduced global PolII occupancy within gene bodies and resulted in delayed transcriptional activation during differentiation of skeletal muscle cells. Conversely, ectopic expression of wild-type Ezh1 led to premature gene activation and rescued PolII-elongation defects in Ezh1-depleted cells. Collectively, these findings reveal an unanticipated role of a PcG protein in promoting mRNA transcription. Examination of 3 different histone modifications, 3 modified forms of RNA polymerase II, Ezh1, Ezh2 and mRNA levels in a skeletal muscle cells at various developmental stages.
Project description:We analyzed the genomic distribution of H3K27me3 in a clone of c-Myc iMEFs (clone C2) either i) wild-type for Ezh2, ii) in the presence of overexpressed exogenous Ezh2, iii) Ezh2-mutant, and iv) Ezh1/Ezh2 pre-deletion (Ezh1/Ezh2 introduced before deletion of endogenous Ezh2) and Ezh2 post-deletion rescue (Ezh2 re-introduced in Ezh2-mutant cells).
Project description:During development, the major class of chromatin regulators is the Polycomb group (PcG) proteins. In this context, they maintain the balance between self-renewal and differentiation. While the role of the Polycomb factor EZH2 has been well described in different developmental contexts, the in vivo activity of EZH1 has long been a puzzle. Here, we show that knocking down EZH1 in chick embryo neural tubes reduces neuronal differentiation without affecting progenitor proliferation or neuronal specification. Transcriptional profiling and functional assays demonstrate that EZH1 mainly acts as a transcriptional activator during neuronal differentiation. Importantly, genes involved in the actin cytoskeleton and cell dynamics that become activated during this process are directly regulated by EZH1. Consistently, depletion of EZH1 in mature neurons leads to morphological alterations and neurite outgrowth defects. Overall, our findings underscore an essential role of EZH1 during early neurogenesis in vivo and highlight the relevance of the dynamic EZH2 to EZH1 switch at the onset of neuronal differentiation.