Project description:Purpose: to demonstrate that G9a maintain CCICs functional triats is independent of its methyltransferase activity. Method: ChIP-seq was applied to CCICs to elucidate the nature of G9a and H3K9me2-regulated differential gene targets by Illumina/Soleza Genome analyzer Results: It was shown that ghe 4,902 G9a-and H3K9me2-targeted genes are broadly idstributed throughout the genome, and both are co-localized at most of the sites in CCICs. G9a and H3K9me2-targeted in CCICs
Project description:Histone H3 lysine 4 monomethylation (H3K4me1) is an evolutionarily conserved feature of enhancer chromatin catalyzed by the COMPASS-like methyltransferase family that includes Trr in Drosophila melanogaster and MLL3 (encoded by KMT2C) and MLL4 (encoded by KMT2D) in mammals. Here we demonstrate that Drosophila embryos expressing catalytically deficient Trr eclose and develop to productive adulthood. Parallel experiments with a trr allele that augments enzyme product specificity show that conversion of H3K4me1 at enhancers to H3K4me2 and H3K4me3 is also compatible with life and results in minimal changes in gene expression. Similarly, loss of the catalytic SET domains of MLL3 and MLL4 in mouse embryonic stem cells (mESCs) does not disrupt selfrenewal. Drosophila embryos with trr alleles encoding catalytic mutants manifest subtle developmental abnormalities when subjected to temperature stress or altered cohesin levels. Collectively, our findings suggest that animal development can occur in the context of Trr or mammalian COMPASS-like proteins deficient in H3K4 monomethylation activity and point to a possible role for H3K4me1 on cis-regulatory elements in specific settings to fine-tune transcriptional regulation in response to environmental stress.
Project description:To measure gene expression difference between wt and g9A knockout ES cells G9A TT2 ES cells (Yokochi et al) were treated with Veh. Or 4OHT (to delete G9A)
Project description:Gene expression in eukaryotes is tightly linked to the methylation state of specific lysine residues within the N-terminal region of the core histone proteins. While the mechanisms connecting histone lysine methylation to effector protein recruitment and control of gene activity are increasingly well understood, it remains unknown whether non-histone chromatin proteins are targets for similar modification-recognition systems. Here we show that histone H3 and the H3 methyltransferase G9a share a conserved methylation motif that is both necessary and sufficient to mediate in vivo interaction with the potent epigenetic regulator Heterochromatin Protein 1 (HP1). As with H3, G9a-HP1 interaction is dependent on lysine methylation and can be reversed by adjacent phosphorylation. NMR analysis demonstrates that the HP1 chromodomain recognizes methyl-G9a through a binding mode similar to that used in recognition of methyl-H3, and that adjacent phosphorylation directly antagonizes G9a-HP1 interaction. In addition to uncovering the chromodomain as a generalized methyl-lysine binding module, these data identify histone-like modification cassettes (or âhistone mimicsâ) as an entirely new class of non-histone methylation targets, and directly demonstrate the relevance of the principles underlying the histone code to the regulation of non-histone proteins. Experiment Overall Design: Two independent Affymetrix gene expression microarray analyses were performed on samples from G9a-deleted MEFs reconstituted with empty vector (delta), wild type FLAG-G9a (WT), FLAG-G9a K165A (K165A) or FLAG-G9a H1093K catalytic mutant (H1093K).
Project description:The role of the histone methyltrasferase G9a (also known as Ehmt2) in the normal heart has not been studied extensively. To identify the genomic regions bound to G9a in cardiomyocytes (CMs),we first generated a conditional, cardiac-specific KO mouse for this gene using the Cre-Lox approach, crossing G9a flox/flox mice with αMHC-MerCreMer mice (Cre mice were used as controls). Then we performed ChIP-seq for G9a and H3K9me2 – the main histone methylation catalysed by the HMT – on isolated G9a-KO and Cre CMs, and considered the best G9a-bound genomic regions as those that had a loss or decrease of G9a binding as well as a lower level of H3K9me2 in G9a-KO CMs. Since G9a contributes to trimethylation of H3K27 at a set of developmental genes through its interaction with PRC2, we also evaluated whether the loss of G9a had an effect on the distribution of this histone mark. To this end, we performed ChIP-seq for H3K27me3 in Cre CMs and G9a-KO CMs. Finally co-immunoprecipitation assays revealed that G9a interacts with Mef2c, thus to elucidate the function of the G9a–Mef2c interaction in adult cardiomyocytes, we used ChIP-seq to define the genomic distribution of Mef2c in Cre CMs and G9a-KO CMs.
Project description:G9a/GLP and Polycomb Repressive Complex 2 (PRC2) are two major epigenetic silencing machineries, which in particular methylate histone H3 on lysines 9 and 27 (H3K9 and H3K27), respectively. Although evidence of a crosstalk between H3K9 and H3K27 methylations has started to emerge, their actual interplay remains elusive. Here, we show that PRC2 and G9a/GLP interact physically and functionally. Moreover, combining different genome-wide approaches, we demonstrate that Ezh2 and G9a/GLP share an important number of common genomic targets, encoding developmental and neuronal regulators. Furthermore, we show that G9a enzymatic activity modulates PRC2 genomic recruitment to a subset of its target genes. Taken together, our findings demonstrate an unanticipated interplay between two main histone lysine methylation mechanisms, which cooperate to maintain silencing of a subset of developmental genes. ChIP-seq has been performed for G9a and Ezh2 in wild type TT2 mES cells or in mES cells lacking both G9a and GLP (G9a-/-GLP-/-). As a control, input DNA was saved before immunoprecipitation. Note that the two inputs (Input_TT2_0 and Input_TT2_1) have been combined and used as control for Ezh2 and G9a ChIP-seq.
Project description:Catalytic-inactivating mutations within the Drosophila enhancer H3K4 monomethyltransferase Trr and its mammalian homologs, MLL3/4, cause only minor changes in gene expression compared to whole-gene deletions for these COMPASS members. To identify essential histone methylatransferase-independent functions of Trr, we screened to identify a minimal Trr domain sufficient to rescue Trr-null lethality and demonstrate that this domain binds and stabilizes Utx in vivo. Using the homologous MLL3/MLL4 human sequences, we mapped a short ~80 amino acid UTX-Stabilization-Domain (USD) that promotes UTX stability in the absence of the rest of MLL3/4. Nuclear UTX stability is enhanced when the USD is fused with the MLL4 HMG-box. Thus, COMPASS-dependent UTX stabilization is an essential non-catalytic function of Trr/MLL3/MLL4, suggesting that stabilizing UTX could be a therapeutic strategy for cancers with MLL3/4 loss-of-function mutations.
Project description:We applied ribosomal footprinting experiment followed by RNA-seq in order to detect circular RNA associated with ribosomes in fly heads.
Project description:PPAR? promotes adipogenesis while Wnt proteins inhibit adipogenesis. However, the mechanisms that control expression of these positive and negative master regulators of adipogenesis remain incompletely understood. By genome-wide histone methylation profiling in preadipocytes, we find that among gene loci encoding adipogenesis regulators, histone methyltransferase (HMT) G9a-mediated repressive epigenetic mark H3K9me2 is enriched on the entire PPAR? locus. H3K9me2 and G9a levels decrease during adipogenesis, which correlates inversely with induction of PPAR?. Removal of H3K9me2 by G9a deletion enhances chromatin opening and binding of adipogenic transcription factor C/EBP-beta to PPAR? promoter, which promotes PPAR? expression. Interestingly, G9a represses PPAR? expression in an HMT activity-dependent manner but facilitates Wnt10a expression independent of its enzymatic activity. Consistently, deletion of G9a or inhibiting G9a HMT activity promotes adipogenesis. Finally, deletion of G9a in mouse adipose tissues increases adipogenic gene expression and tissue weight. Thus, by inhibiting PPAR? expression and facilitating Wnt10a expression, G9a represses adipogenesis. Examination of 3 different histone modification changes in 3T3-L1 preadipocytes