Project description:In eukaryotic cells, DNA is tightly packed in the nucleus in chromatin which has histones as its main protein component. Histones are subject to a large number of distinct post-translational modifications, whose sequential or combinatorial action affects genome function. Here, we report the identification of acetylation at lysine 36 in histone H3 (H3K36ac) as a modification in Arabidopsis thaliana. H3K36ac was found to be an evolutionary conserved modification in seed plants. It is highly enriched in euchromatin and very low in heterochromatin. Genome-wide ChIP-seq experiments revealed that H3K36ac is generally found at the 5â?? end of genes. Independently of gene length, H3K36ac covers about 500 bp, about two to three nucleosomes, immediately downstream of the transcriptional start. H3K36ac overlaps with H3K4me3 and the H2A.Z histone variant. The histone acetyl transferase GCN5 and the histone deacetylase HDA19 are required for normal steady state levels of H3K36ac in plants. There is negative crosstalk between H3K36ac and H3K36me3, mediated by the histone methyl transferase SDG8 and GCN5. H3K36ac levels are associated with transcriptional activity but show no linear relation. Instead, H3K36ac is a binary indicator of transcription Characterization of the genome-wide distribution of H3K36ac using ChIP-seq. Analysis of the mechanistic crosstalk in the deposition of acetylation and methylation at H3K36 by ChIP-seq of H3K36ac and H3K36me3 in sdg8-2 and gcn5-1, respectively.
Project description:In eukaryotic cells, DNA is tightly packed in the nucleus in chromatin which has histones as its main protein component. Histones are subject to a large number of distinct post-translational modifications, whose sequential or combinatorial action affects genome function. Here, we report the identification of acetylation at lysine 36 in histone H3 (H3K36ac) as a modification in Arabidopsis thaliana. H3K36ac was found to be an evolutionary conserved modification in seed plants. It is highly enriched in euchromatin and very low in heterochromatin. Genome-wide ChIP-seq experiments revealed that H3K36ac is generally found at the 5’ end of genes. Independently of gene length, H3K36ac covers about 500 bp, about two to three nucleosomes, immediately downstream of the transcriptional start. H3K36ac overlaps with H3K4me3 and the H2A.Z histone variant. The histone acetyl transferase GCN5 and the histone deacetylase HDA19 are required for normal steady state levels of H3K36ac in plants. There is negative crosstalk between H3K36ac and H3K36me3, mediated by the histone methyl transferase SDG8 and GCN5. H3K36ac levels are associated with transcriptional activity but show no linear relation. Instead, H3K36ac is a binary indicator of transcription
Project description:We report the application of Next-generation sequencing (NGS) for high-throughput profiling of N4-acetylcytosine (4acC) DNA modification in Arabidopsis thaliana. We find that 4acC peaks mostly distribute in the euchromatin regions and are present in nearly half of the protein-coding genes in Arabidopsis. 4acC mainly locates around transcription start sites (TSSs) of protein-coding genes and positively correlates with gene expression level . Compared to non-4acC marked genes, 4acC marked genes display a higher methylation level of 5mC in the CG context within coding regions, but a lower methylation level of 5mC in the CHG and CHH contexts. In addition, 4acC peaks showed higher overlaps with active histone modification marks than by chance, but similar overlaps with repressive histone modification marks. We observed complex cooperative interactions among 4acC, 5mC, and histone modifications on gene transcription. 4acC containing genes with low level of mCG, or active histone modification marks displayed a higher expression. In sum, we have uncovered 4acC as a hitherto unknown epigenetic DNA mark that is associated with gene expression in Arabidopsis, and suggest potential cross-talks among epigenetic marks for gene expression.
Project description:Histone lysine (K) acetylation is a major mechanism by which cells regulate the structure and function of chromatin, and new sites of acetylation continue to be discovered. Here we identify and characterize histone H3K36 acetylation (H3K36ac). By mass spectrometric analysis of H3 purified from Tetrahymena thermophila and S. cerevisiae (yeast), we find that H3K36 is acetylated in addition to being methylated. Using an antibody specific to H3K36ac, we show that this modification is conserved in mammals. In yeast, genome-wide ChIP-chip experiments show that H3K36ac is localized predominantly to the promoters of RNA polymerase II-transcribed genes, a pattern mutually exclusive to that of H3K36 methylation. The pattern of H3K36ac localization is similar to that of other sites of H3 acetylation, including H3K9ac and H3K14ac. Using histone acetyltransferase complexes purified from yeast, we show that the Gcn5-containing SAGA complex specifically acetylates H3K36 in vitro. Deletion of GCN5 completely abolishes H3K36ac in vivo. The regulation of H3K36ac by Gcn5 suggests a function for this modification in transcription. These data expand our knowledge of the genomic targets of Gcn5, show H3K36ac is highly conserved, and raise the intriguing possibility that the transition between H3K36ac and H3K36me acts as a switch in chromatin function along transcription units. This SuperSeries is composed of the SubSeries listed below.
Project description:We report the identification of 67 previously undescribed histone modifications, increasing the current number of known histone marks by about 70%. We further investigated one of the marks, lysine crotonylation (Kcr), confirming that it represents an evolutionarily-conserved histone posttranslational modification. The unique structure and genomic localization of histone Kcr suggest that it is mechanistically and functionally different from histone lysine acetylation (Kac). Specifically, in both human somatic and mouse male germ cell genomes, histone Kcr marks either active promoters or potential enhancers. In male germinal cells immediately following meiosis, Kcr is enriched on sex chromosomes and specifically marks testis-specific genes, including a significant proportion of X-linked genes that escape sex chromosome inactivation in haploid cells. These results therefore dramatically extend the repertoire of histone PTM sites and designate Kcr as a specific mark of active sex chromosome-linked genes in postmeiotic male germ cells. 2 histone marks (pan-lysine acetylation and pan-lysine crotonylation) were studied in 1 human cell type and 2 mouse cell types using ChIP-Seq. Input was sequenced for each cell type as a control. Pan-anti_Kac and pan-anti_Kcr antibodies were custom developed with PTM BioLab, Co., Ltd (Chicago, IL).
Project description:Bioinformatics powered correlative analysis of epigenomic patterns is an effective method to help derive biological hypotheses that can be tested genetically or biochemically. To accommodate the variety and complexity of epigenomic and transcriptomic patterns, ANchored COrrelative Patterns (ANCORP) was developed as a platform to integrate and intuitively visualize a large number of genome-wide profiles. With global profiles of 9 histone modifications mapped by ChIP-seq and a strand-specific RNA-seq dataset, we have applied the ANCORP-genetics pipeline for hypothesis building and testing in order to understand how global transcription may be regulated by epigenetic pathways such as histone modifications. It was found that intragenic antisense RNAs were depleted from genes with strong gene-body H3K36me2 mark and cytosine methylation enrichments but were significantly overrepresented in H3K4me3/H3K27me3 bivalent genes. Moreover, gene body H3K36me2 and DNA methylation anti-correlated with multiple active chromatin marks including H3K4me2/3, H3K9Ac and H3K18Ac. These observations lead us to hypothesize that H3K36me2 and DNA methylation may synergistically repress active chromatin marks in gene bodies and subsequently inhibit transcription of the antisense strand. Mutant analyses revealed that Polymerase Associated Factors (PAF) may be universally required for modulating NAT abundance whereas the role for the 5mC and H3K36me marks are more locus specific. H3K36me and PAF may either repress or permit the accumulation NATs depending on the chromatin state context in a particular transcription unit. Interestingly, the activation of antisense RNA in sdg8-2 or elf8-1 mutants does not associate with any increase of histone marks in gene bodies that are known to correlate with gene activation. Our results suggest that ANCORP-genetics is an effective approach to uncover epigenetic regulatory mechanisms by leveraging on the rapid advances in sequencing technologies and the resultant wealth of genome-wide information.
Project description:We report the identification of 67 previously undescribed histone modifications, increasing the current number of known histone marks by about 70%. We further investigated one of the marks, lysine crotonylation (Kcr), confirming that it represents an evolutionarily-conserved histone posttranslational modification. The unique structure and genomic localization of histone Kcr suggest that it is mechanistically and functionally different from histone lysine acetylation (Kac). Specifically, in both human somatic and mouse male germ cell genomes, histone Kcr marks either active promoters or potential enhancers. In male germinal cells immediately following meiosis, Kcr is enriched on sex chromosomes and specifically marks testis-specific genes, including a significant proportion of X-linked genes that escape sex chromosome inactivation in haploid cells. These results therefore dramatically extend the repertoire of histone PTM sites and designate Kcr as a specific mark of active sex chromosome-linked genes in postmeiotic male germ cells.