Project description:This goal of this study was to identify genes that are deregulated in the absence of EZH2 in early lymphocyte progenitors. Due to a requirement for EZH2 to repress Cdkn2a in early B and T cell development we generated Cdkn2a-/-Ezh2fl/fl Il7racre/+ mice. We examined gene expression by RNA-sequencing in sorted pro-B cells (B220+CD19+CD43+), DN3 cells (Lin- CD25+ CD117-), from Cdkn2a-/- Ezh2fl/fl Il7racre/+ and Cdkn2a-/- Il7racre/+ control mice. Reads were aligned to the mm10 reference genome by Tophat2.1.0. Reads were assigned to genes using the htseq-count tool from HTSeq v 0.6.1 and gene annotations from Ensembl release 78. Differential expression was calculated across 3 independent replicates by EdgeR. We found that pro-B and DN3 cells remain specified to their respective lineages despite loss of EZH2. In contrast, loss of EZH2 led to expression of alternate lineage determinants in pro-B but not DN3 cells indicating that EZH2 is required for lineage commitment in B, but not T lymphocyte progenitors.
Project description:This goal of this study was to identify genes that are deregulated in the absence of EZH2 in early lymphocyte progenitors. We examined gene expression by RNA-sequencing in sorted CLPs (Lin-CD117int CD127+ CD135+), pro-B cells (B220+CD19+CD43+), DN3 cells (Lin- CD25+ CD117-), splenic NK cells (Lin-NK1.1+DX5+) and bone marrow ILC2 cells (Lin- Sca1+CD127+) from Ezh2fl/fl Il7racre/+ and Il7racre/+ control mice. Reads were aligned to the mm10 reference genome by Tophat2.1.0. Reads were assigned to genes using the htseq-count tool from HTSeq v 0.6.1 and gene annotations from Ensembl release 78. Differential expression was calculated across 2-3 independent replicates by EdgeR. We found that CLPs, ILC2s, and splenic NK cells maintained their normal transcriptional programs despite loss of EZH2. In contrast, loss of EZH2 caused over 1000 genes to be deregulated in pro-B and DN3 cells indicating that EZH2 is required for transcriptomic stability in adaptive, but not innate lymphocyte progenitors.
Project description:Inactivation of the tumor suppressor genes TP53 and CDKN2A occurs early during GEJ tumorigenesis. However, due to a paucity of GEJ-specific disease models, cancer-promoting consequences of TP53 and CDKN2A inactivation at the GEJ have been incompletely characterized. Here we report the development of the first wild-type primary human GEJ organoid model, as well as a CRISPR-edited transformed GEJ organoid model. CRISPR/Cas9 engineering to inactivate TP53 and CDKN2A (TP53/CDKN2A KO) in GEJ organoids induced morphologic dysplasia as well as pro-neoplastic features in vitro and tumor formation in vivo. Notably, lipidomic profiling identified several Platelet-Activating Factors (PTAFs) among the most upregulated lipids in CRISPR-edited organoids; and importantly, PT AF/PT AFR abrogation by siRNA knockdown or a pharmacologic inhibitor (WEB2086) significantly blocked proliferation and other pro-neoplastic features of TP53/CDKN2A KO GEJ organoids in vitro and tumor formation in vivo. In addition, murine xenografts derived from Eso26, an established esophageal adenocarcinoma (EAC) cell line, were suppressed by WEB2086. Mechanistically, TP53/CDKN2A dual inactivation disrupted both the transcriptome and the DNA methylome, likely mediated by key transcription factors, particularly Forkhead Box M1 (FOXM1). Importantly, FOXM1 activated PTAFR transcription by binding to the PTAFR promoter, further amplifying the PTAF-PTAFR pathway. In summary, we established a robust model system for investigating early GEJ neoplastic events, identified crucial metabolic and epigenomic changes occurring during GEJ model tumorigenesis, and discovered a potential cancer-therapeutic strategy, while providing insights into pro-neoplastic mechanisms associated with TP53/CDKN2A inactivation in early GEJ neoplasia.
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:The repertoire of diverse T-cell receptors (TCRs) and immunoglobulins is generated through restrictedly lineage and stage specific DNA rearrangements of variable (V), diversity (D) and Joining (J) gene segments at early T and B cell development. Histone modifications has been demonstrated to ensure proper VDJ recombination. However, the epigenetic mechanisms and the role of enzymes that catalyze epigenetic modifications in regulating VDJ recombination still remain largely unexplored. Herein we report that deletion of SetD2, the histone methyltransferase to catalyze the trimethylation of lysine 36 on histone 3, leads to severe lymphopenia due to development blockage of T lymphocyte at the double negative 3 (DN3) stage and differentiation arrest of B cell development at the pro-B stage in genetically engineered mouse models. SetD2 deficiency causes a loss of H3K36me3 and markedly impairs VDJ rearrangement of TCRβ and immunoglobulin heavy chain. Our study demonstrates that SetD2 and its mediated H3K36M3 modification are required for the VDJ recombination and normal lymphocyte development.
Project description:EZH2 has been studied most extensively in the context of PRC2-dependent gene repression. Paradoxically, accumulating evidence indicates non-canonical functions for EZH2 in cancer contexts including promoting gene expression in triple negative breast cancer (TNBC) cells through interactions with the transcription factor NF-kB. We define a genomic profile of EZH2 and NF-kB factor RelA, RelB, and NFKB2/p52 co-localization and positive regulation of a subset of NF-kB targets and genes associated with oncogenic functions in TNBC, which is enriched in patient datasets. We demonstrate interaction between EZH2 and RelA requiring the recently identified EZH2 transactivation domain (TAD), which mediates EZH2 recruitment to and activation of certain NF-kB-dependent genes, and supports downstream stemness phenotypes in TNBC cells. Interestingly, EZH2-NF-kB positive regulation of genes and stemness does not require PRC2. This study provides new insight into pro-oncogenic regulatory functions for EZH2 in breast cancer through PRC2-independent, and NF-kB-dependent regulatory mechanisms.
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.