Project description:We report a direct interaction between RNA epigenome and DNA epigenome. We demonstrate that m6A methyltransferase METTL3 regulates DNA methylation levels co-transcriptionally. We observed a genome-wide correlation between m6A / METTL3 and occupancy by the DNA demethylase TET1, and m6A reader physically interacts and recruits TET1 to m6A-associated chromatin regions. Our results demonstrates an original but unheeded feed-back regulatory mechanism from RNA epigenome to DNA epigenome and detect a new aspect of epigenetic crosstalk to regulate gene expression.
Project description:The pluripotent ground state is defined as a basal state free of epigenetic restrictions, which influence lineage specification. While naive embryonic stem cells (ESCs) can be maintained in a hypomethylated state with open chromatin when grown using two small-molecule inhibitors (2i)/leukemia inhibitory factor (LIF), in contrast to serum/LIF-grown ESCs that resemble early post-implantation embryos, broader features of the ground-state pluripotent epigenome are not well understood. We identified epigenetic features of mouse ESCs cultured using 2i/LIF or serum/LIF by proteomic profiling of chromatin-associated complexes and histone modifications. Polycomb-repressive complex 2 (PRC2) and its product H3K27me3 are highly abundant in 2i/LIF ESCs, and H3K27me3 is distributed genome-wide in a CpG-dependent fashion. Consistently, PRC2-deficient ESCs showed increased DNA methylation at sites normally occupied by H3K27me3 and increased H4 acetylation. Inhibiting DNA methylation in PRC2-deficient ESCs did not affect their viability or transcriptome. Our findings suggest a unique H3K27me3 configuration protects naive ESCs from lineage priming, and they reveal widespread epigenetic crosstalk in ground-state pluripotency.
Project description:Biochemical crosstalk between two or more histone modifications is often observed in epigenetic enzyme regulation but its functional significance in cells has been difficult to discern. Prior enzymatic studies have revealed that Lys14 acetylation of histone H3 can inhibit Lys4 demethylation by lysine specific demethylase 1 (LSD1). Here we have engineered a mutant form of LSD1, Y391K, which renders the nucleosome demethylase activity of LSD1 insensitive to Lys14 acetylation. Y391K LSD1 knockin cells show increased repression of a set of genes associated with cellular adhesion. Chromatin profiling revealed that the cis-regulatory regions of these silenced genes display a higher level of H3 Lys14 acetylation than the baseline in unedited, parental cells. Y391K LSD1 knockin cells show diminished H3 mono-methyl Lys4 in the vicinity of these silenced genes, consistent with a role for enhanced LSD1 demethylase activity in these regions. These findings illuminate the functional consequences of disconnecting histone modification crosstalk for a key epigenetic enzyme in gene and chromatin regulation.
Project description:Epigenetic regulation is a dynamic and reversible process that controls gene expression. Abnormal function results in downregulation or upregulation of pathways leading to diseases, such as cancer. The enzymes that establish and maintain epigenetic marks, such as histone methyltransferases (HMTs), are therapeutic targets as their and, importantly, the epigenetic modifications are reversible. Noteworthy, HMTs, as the other epigenetic enzymes and readers, form together multiprotein complexes that in concert regulate histone marks. To probe the epigenetic protein complexes in a biological system, we developed a reliable chemical biology high-content imaging strategy to screen compound libraries on multiple histone marks inside cells simultaneously. The advantage is double: (1) it identifies directly a drug that is active in cells on a specific histone mark and (2) it reveals the crosstalk between the epigenetic marks. By this approach, we identified that compound 4, a published CARM1 (PRMT4) inhibitor, inhibits both histone mark H3R2me2a (regulated by CARM1) and H3K79me2 (regulated by DOT1L) pointing out a synergistic interaction between the two HMTs. The results obtained by the screening assay were validated by mass spectrometry and other techniques confirming the crosstalk between the two marks and HMTs. Prompted by the interaction between CARM1 and DOT1L we combined compound 4 and DOT1L inhibitor EPZ-5676 resulting in a stronger cell proliferation inhibition and apoptosis, indicating that our approach provides also a novel strategy to identify effective synergistic drug combinations for cancer therapy.
Project description:This SuperSeries is composed of the following subset Series: GSE26018: Crosstalk between gene body DNA methylation, H3K9me3 and H3K36me3 chromatin marks and transcription [HuEx-1_0-st] GSE26019: Crosstalk between gene body DNA methylation, H3K9me3 and H3K36me3 chromatin marks and transcription [HuGene-1_0-st] GSE26038: Crosstalk between gene body DNA methylation, H3K9me3 and H3K36me3 chromatin marks and transcription [HuEx-1_0-st, transcript] GSE26040: Relationship between gene body DNA methylation and intragenic H3K9me3 and H3K36me3 chromatin marks Refer to individual Series
Project description:Epithelial to Mesenchymal Transition (EMT) renders epithelial cells to acquire migratory characteristics during development and cancer metastasis. While epigenetic and splicing changes have been implicated in EMT, the mechanisms governing their crosstalk remain poorly understood. Here, we identify C2H2 zinc finger protein, ZNF827, a novel factor, is strongly induced during important EMT mediated processes including in brain development and breast cancer metastasis and is required for the molecular and phenotypic changes underlying EMT in these processes. Mechanistically, ZNF827 mediated these responses by orchestrating a large-scale remodeling of the splicing landscape by recruiting HDAC1 for epigenetic modulation of distinct genomic loci, thereby slowing RNA Pol II progression and altering the splicing of transcripts encoding key EMT regulators in cis. These findings reveal an unprecedented complexity between epigenetic landscape and splicing and identifies ZNF827 as a master regulator coupling these processes during EMT in brain development and breast cancer metastasis.