Histone H3 Lysine 4 mono-, di- and trimethyl and CTCF in CD4+CD25+CD45RA+ regulatory and conventional CD4+CD25- T-cells
ABSTRACT: Analysis of Histone H3 Lysine 4 mono-, di- and trimethyl and the boundary protein CTCF in CD4+CD25+CD45RA+ regulatory T-cells and conventional CD4+CD25- T-cells. To investigate regulatory functions or potential new transcription start sites in Treg and Tconv cells, we investigated the associated histone modifications. Mono- and dimethylation of histone 3 lysin 4 (H3K4) were previously shown to mark enhancer regions, whereas H3K4 trimethylation generally associates with transcription start sites. At imprinted loci, binding of the insulator protein CTCF, which restricts or directs enhancer-promoter interactions, is often regulated by DNA-methylation. Therefore we performed ChIP-on-chip experiments (chromatin immunoprecipitation followed by microarray hybridization; samples were amplified with ligation mediated PCR [see label protocol for the procedure] prior to labeling) for mono- di- and trimethylation of histone 3 lysin 4 and of CTCF in expanded Treg and Tconv cells. Keywords: ChIP-on-chip Overall design: ChIP-on-chip experiments for H3K4 mono-, di- and trimethyl and CTCF in CD4+CD25+CD45RA+ regulatory T-cells and conventional CD4+CD25- T-cells were co-hybridizied with the input. Three biologiacal replicates (rep1-3) were performed for every histone mark, two CTCF (rep1 and rep2).
INSTRUMENT(S): Human custom chip-on-chip 2x105k tiling microarray AMADID: 018053
Project description:Analysis of Histone H3 Lysine 4 mono-, di- and trimethyl and the boundary protein CTCF in CD4+CD25+CD45RA+ regulatory T-cells and conventional CD4+CD25- T-cells. To investigate regulatory functions or potential new transcription start sites in Treg and Tconv cells, we investigated the associated histone modifications. Mono- and dimethylation of histone 3 lysin 4 (H3K4) were previously shown to mark enhancer regions, whereas H3K4 trimethylation generally associates with transcription start sites. At imprinted loci, binding of the insulator protein CTCF, which restricts or directs enhancer-promoter interactions, is often regulated by DNA-methylation. Therefore we performed ChIP-on-chip experiments (chromatin immunoprecipitation followed by microarray hybridization; samples were amplified with ligation mediated PCR [see label protocol for the procedure] prior to labeling) for mono- di- and trimethylation of histone 3 lysin 4 and of CTCF in expanded Treg and Tconv cells. Keywords: ChIP-on-chip ChIP-on-chip experiments for H3K4 mono-, di- and trimethyl and CTCF in CD4+CD25+CD45RA+ regulatory T-cells and conventional CD4+CD25- T-cells were co-hybridizied with the input. Three biologiacal replicates (rep1-3) were performed for every histone mark, two CTCF (rep1 and rep2).
Project description:This SuperSeries is composed of the following subset Series: GSE14232: Transcriptome analysis of freshly sorted and expanded regulatory and conventional T cells GSE14233: Detection of differentially methylated regions in CD4+CD25+CD45RA+ regulatory T-cells and conventional CD4+CD25- T-cells GSE14234: Histone H3 Lysine 4 mono-, di- and trimethyl and CTCF in CD4+CD25+CD45RA+ regulatory and conventional CD4+CD25- T-cells Refer to individual Series
Project description:Histone H3 lysine-4 (H3K4) methylation is associated with transcribed genes in eukaryotes. In Drosophila and mammals, both di- and tri-methylation of H3K4 are associated with gene activation. In contrast to animals, in Arabidopsis H3K4 trimethylation, but not mono- or di-methylation of H3K4, has been implicated in transcriptional activation. H3K4 methylation is catalyzed by the H3K4 methyltransferase complexes known as COMPASS or COMPASS-like in yeast and mammals. Here, we report that Arabidopsis homologs of the COMPASS and COMPASS-like complex core components known as Ash2, RbBP5, and WDR5 in humans form a nuclear subcomplex during vegetative and reproductive development, which can associate with multiple putative H3K4 methyltransferases. Loss of function of ARABIDOPSIS Ash2 RELATIVE (ASH2R) causes a great decrease in genome-wide H3K4 trimethylation, but not in di- or mono-methylation. Knockdown of ASH2R or the RbBP5 homolog suppresses the expression of a crucial Arabidopsis floral repressor, FLOWERING LOCUS C (FLC), and FLC homologs resulting in accelerated floral transition. ASH2R binds to the chromatin of FLC and FLC homologs in vivo and is required for H3K4 trimethylation, but not for H3K4 dimethylation in these loci; overexpression of ASH2R causes elevated H3K4 trimethylation, but not H3K4 dimethylation, in its target genes FLC and FLC homologs, resulting in activation of these gene expression and consequent late flowering. These results strongly suggest that H3K4 trimethylation in FLC and its homologs can activate their expression, providing concrete evidence that H3K4 trimethylation accumulation can activate eukaryotic gene expression. Furthermore, our findings suggest that there are multiple COMPASS-like complexes in Arabidopsis and that these complexes deposit trimethyl but not di- or mono-methyl H3K4 in target genes to promote their expression, providing a molecular explanation for the observed coupling of H3K4 trimethylation (but not H3K4 dimethylation) with active gene expression in Arabidopsis.
Project description:PRDM9 (PR domain-containing protein 9) is a meiosis-specific protein that trimethylates H3K4 and controls the activation of recombination hot spots. It is an essential enzyme in the progression of early meiotic prophase. Disruption of the PRDM9 gene results in sterility in mice. In human, several PRDM9 SNPs have been implicated in sterility as well. Here we report on kinetic studies of H3K4 methylation by PRDM9 in vitro indicating that PRDM9 is a highly active histone methyltransferase catalyzing mono-, di-, and trimethylation of the H3K4 mark. Screening for other potential histone marks, we identified H3K36 as a second histone residue that could also be mono-, di-, and trimethylated by PRDM9 as efficiently as H3K4. Overexpression of PRDM9 in HEK293 cells also resulted in a significant increase in trimethylated H3K36 and H3K4 further confirming our in vitro observations. Our findings indicate that PRDM9 may play critical roles through H3K36 trimethylation in cells.
Project description:DNA replication is a highly regulated process that is initiated from replication origins, but the elements of chromatin structure that contribute to origin activity have not been fully elucidated. To identify histone post-translational modifications important for DNA replication, we initiated a genetic screen to identify interactions between genes encoding chromatin-modifying enzymes and those encoding proteins required for origin function in the budding yeast Saccharomyces cerevisiae. We found that enzymes required for histone H3K4 methylation, both the histone methyltransferase Set1 and the E3 ubiquitin ligase Bre1, are required for robust growth of several hypomorphic replication mutants, including cdc6-1. Consistent with a role for these enzymes in DNA replication, we found that both Set1 and Bre1 are required for efficient minichromosome maintenance. These phenotypes are recapitulated in yeast strains bearing mutations in the histone substrates (H3K4 and H2BK123). Set1 functions as part of the COMPASS complex to mono-, di-, and tri-methylate H3K4. By analyzing strains lacking specific COMPASS complex members or containing H2B mutations that differentially affect H3K4 methylation states, we determined that these replication defects were due to loss of H3K4 di-methylation. Furthermore, histone H3K4 di-methylation is enriched at chromosomal origins. These data suggest that H3K4 di-methylation is necessary and sufficient for normal origin function. We propose that histone H3K4 di-methylation functions in concert with other histone post-translational modifications to support robust genome duplication.
Project description:In eukaryotes, the post-translational addition of methyl groups to histone H3 lysine 4 (H3K4) plays key roles in maintenance and establishment of appropriate gene expression patterns and chromatin states. We report here that an essential locus within chromosome 3L centric heterochromatin encodes the previously uncharacterized Drosophila melanogaster ortholog (dSet1, CG40351) of the Set1 H3K4 histone methyltransferase (HMT). Our results suggest that dSet1 acts as a "global" or general H3K4 di- and trimethyl HMT in Drosophila. Levels of H3K4 di- and trimethylation are significantly reduced in dSet1 mutants during late larval and post-larval stages, but not in animals carrying mutations in genes encoding other well-characterized H3K4 HMTs such as trr, trx, and ash1. The latter results suggest that Trr, Trx, and Ash1 may play more specific roles in regulating key cellular targets and pathways and/or act as global H3K4 HMTs earlier in development. In yeast and mammalian cells, the HMT activity of Set1 proteins is mediated through an evolutionarily conserved protein complex known as Complex of Proteins Associated with Set1 (COMPASS). We present biochemical evidence that dSet1 interacts with members of a putative Drosophila COMPASS complex and genetic evidence that these members are functionally required for H3K4 methylation. Taken together, our results suggest that dSet1 is responsible for the bulk of H3K4 di- and trimethylation throughout Drosophila development, thus providing a model system for better understanding the requirements for and functions of these modifications in metazoans.
Project description:The mixed lineage leukemia-1 (MLL1) core complex predominantly catalyzes mono- and dimethylation of histone H3 at lysine 4 (H3K4) and is frequently altered in aggressive acute leukemias. The molecular mechanisms that account for conversion of mono- to dimethyl H3K4 (H3K4me1,2) are not well understood. In this investigation, we report that the suppressor of variegation, enhancer of zeste, trithorax (SET) domains from human MLL1 and Drosophila Trithorax undergo robust intramolecular automethylation reactions at an evolutionarily conserved cysteine residue in the active site, which is inhibited by unmodified histone H3. The location of the automethylation in the SET-I subdomain indicates that the MLL1 SET domain possesses significantly more conformational plasticity in solution than suggested by its crystal structure. We also report that MLL1 methylates Ash2L in the absence of histone H3, but only when assembled within a complex with WDR5 and RbBP5, suggesting a restraint for the architectural arrangement of subunits within the complex. Using MLL1 and Ash2L automethylation reactions as probes for histone binding, we observed that both automethylation reactions are significantly inhibited by stoichiometric amounts of unmethylated histone H3, but not by histones previously mono-, di-, or trimethylated at H3K4. These results suggest that the H3K4me1 intermediate does not significantly bind to the MLL1 SET domain during the dimethylation reaction. Consistent with this hypothesis, we demonstrate that the MLL1 core complex assembled with a catalytically inactive SET domain variant preferentially catalyzes H3K4 dimethylation using the H3K4me1 substrate. Taken together, these results are consistent with a "two-active site" model for multiple H3K4 methylation by the MLL1 core complex.
Project description:Histone methylation at specific lysine residues brings about various downstream events that are mediated by different effector proteins. The WD40 domain of WDR5 represents a new class of histone methyl-lysine recognition domains that is important for recruiting H3K4 methyltransferases to K4-dimethylated histone H3 tail as well as for global and gene-specific K4 trimethylation. Here we report the crystal structures of full-length WDR5, WDR5Delta23 and its complexes with unmodified, mono-, di- and trimethylated histone H3K4 peptides. The structures reveal that WDR5 is able to bind all of these histone H3 peptides, but only H3K4me2 peptide forms extra interactions with WDR5 by use of both water-mediated hydrogen bonding and the altered hydrophilicity of the modified lysine 4. We propose a mechanism for the involvement of WDR5 in binding and presenting histone H3K4 for further methylation as a component of MLL complexes.
Project description:The gut microbiota in chicken has long been studied, mostly from the perspective of growth performance. However, there are some immunological studies regarding gut homeostasis in chicken. Although CD4+CD25+ T cells are reported to act as regulatory T cells (Tregs) in chicken, there have been no studies showing the relationship between gut microbiota and Tregs. Therefore, we established a model for 'antibiotics (ABX)-treated chickens' through administration of an antibiotic cocktail consisting of ampicillin, gentamycin, neomycin, metronidazole, and vancomycin in water for 7 days. CD4+CD8-CD25+ and CD4+CD8+CD25+ T cells in cecal tonsils were significantly decreased in this model. Gram-positive bacteria, especially Clostridia, was responsible for the changes in CD4+CD8-CD25+ or CD4+CD8+CD25+ T cells in cecal tonsils. Feeding ABX-treated chickens with acetate recovered CD4+CD8-CD25+ and CD4+CD8+CD25+ T cells in cecal tonsils. GPR43, a receptor for acetate, was highly expressed in CD4+CD8-CD25+ T cells. In conclusion, our study demonstrated that the gut microbiota can regulate the population of CD4+CD8-CD25+ and CD4+CD8+CD25+ T cells, and that acetate is responsible for the induction of CD4+CD8-CD25+ T cells in cecal tonsils via GPR43.