Project description:H4K12 acetylation mapped by chromatin Chromatin immunoprecipitation (ChIP) in human sperm. ChIP mapping of chromatin modification. Three biological replicates hybridized to each of two chips.
Project description:Map the histone H3K9/14 acetylation regions of in human cells at 7 common fragile sites and their flanking non-fragile sequences as well as a 200kb containing the rare fragile site FRAXA, a 1,075kb non-fragile region on chr22, a hyperacetylated region HALPHA44, and a heterochromatic region HET405. The acetylated regions were mapped in untreated, aphidicolin(APH)-treated, trichostatin(TSA)-treated, and TSA plus APH-treated cells by combining the chromatin-immunoprecipitation with a tiled microarray platform (ChIP-chip).
Project description:Full title: Complex patterns of genome accessibility discriminate sites of PcG repression, H4K16 acetylation and replication initiation Histone modifications have been proposed to regulate gene expression in part by modulating DNA accessibility and higher-order chromatin structure. However, there is limited direct evidence to support structural differences between euchromatic and heterochromatic fibers in the nucleus. To ask how histone modifications relate to chromatin compaction, we measured DNA accessibility throughout the genome by combining M.SssI methylase footprinting with methylated DNA immunoprecipitation (MeDIP-footprint). In the Drosophila genome, we find that accessibility to DNA methylase is variable in a manner that relates to the differential distribution of active and repressive histone modifications. Active promoters are highly permissive to M.SssI activity, yet inactive chromosomal domains decorated with H3 lysine 27 trimethylation are least accessible providing in vivo evidence for Polycomb-mediated chromatin compaction. Conversely, DNA accessibility is increased at active chromosomal regions marked with H4 lysine 16 acetylation and at the dosage-compensated male X chromosome suggesting that Drosophila transcriptional dosage compensation is facilitated by more permissive chromatin structure. Interestingly early replicating chromosomal regions and sites of replication initiation show also higher accessibility linking temporal and spatial control of genome duplication to the structural organization of chromatin. In conclusion, using a novel protocol we generated a comprehensive view of DNA accessibility and uncover different levels of chromatin organization, which are delineated by distinct patterns of posttranslational histone modifications and replication. Keywords: cell type comparison, ChIP-chip, MeDIP-footprint, RNA-seq, ChIP-seq MeDIP-footprint and ChIP-chip: ChIP-chip was performed for H3K4me3, H3K36me2, H3K36me3, H3K27me3, and H3K9me2 in Kc cells. We measured DNA accessibility throughout the genome by combining M.SssI methylase footprinting with methylated DNA immunoprecipitation (MeDIP-footprint) in Kc and S2 cells. RNA-seq: cDNA from RNA from Drosophila Kc cells was sequenced using Illumina deep sequencing. Reads were mapped and the abundance of all transcripts was determined. ChIP-seq: PSC ChIP from Drosophila Kc cells was sequenced using Illumina deep sequencing in three lanes. Reads were mapped and the binding profile of PSC was determined.
Project description:During mammalian spermatogenesis, male germ cells undergo dramatic reorganization of chromatin, whereby 90-99% of histones are evicted and replaced by protamines. This reorganization prominently features histone acetylation to loosen chromatin structure. Given the potential role of retained histones in fertility and early embryonic development, the genomic location of retained nucleosomes is of great interest. However, the ultimate position and mechanisms underlying nucleosome eviction/retention are poorly understood, including several studies utilizing MNase-seq methodologies, but reporting remarkably dissimilar locations. Here, we utilized ATAC-seq to determine the location of retained nucleosomes in mouse sperm and found enrichment at promoters, but also retention at inter- and intragenic regions, and repetitive elements. We further investigated nucleosome eviction/retention by generating pre-meiotic, germ cell specific, conditional knockout mice for the histone acetyltransferase Gcn5, a key histone acetyltransferase. Gcn5cKO germ cells exhibited abnormal chromatin dynamics during spermiogenesis, including diminished nucleosome eviction leading to increased histone retention in sperm. These mice exhibited severe reproductive phenotypes: abnormal sperm production, sperm morphology, and ultimately, male infertility. Our findings demonstrate Gcn5 mediated histone acetylation promotes chromatin accessibility and nucleosome eviction in spermiogenesis, and that loss of histone acetylation leads to defects that disrupt male fertility and potentially, early embryogenesis.
Project description:During mammalian spermatogenesis, male germ cells undergo dramatic reorganization of chromatin, whereby 90-99% of histones are evicted and replaced by protamines. This reorganization prominently features histone acetylation to loosen chromatin structure. Given the potential role of retained histones in fertility and early embryonic development, the genomic location of retained nucleosomes is of great interest. However, the ultimate position and mechanisms underlying nucleosome eviction/retention are poorly understood, including several studies utilizing MNase-seq methodologies, but reporting remarkably dissimilar locations. Here, we utilized ATAC-seq to determine the location of retained nucleosomes in mouse sperm and found enrichment at promoters, but also retention at inter- and intragenic regions, and repetitive elements. We further investigated nucleosome eviction/retention by generating pre-meiotic, germ cell specific, conditional knockout mice for the histone acetyltransferase Gcn5, a key histone acetyltransferase. Gcn5cKO germ cells exhibited abnormal chromatin dynamics during spermiogenesis, including diminished nucleosome eviction leading to increased histone retention in sperm. These mice exhibited severe reproductive phenotypes: abnormal sperm production, sperm morphology, and ultimately, male infertility. Our findings demonstrate Gcn5 mediated histone acetylation promotes chromatin accessibility and nucleosome eviction in spermiogenesis, and that loss of histone acetylation leads to defects that disrupt male fertility and potentially, early embryogenesis.
Project description:During mammalian spermatogenesis, male germ cells undergo dramatic reorganization of chromatin, whereby 90-99% of histones are evicted and replaced by protamines. This reorganization prominently features histone acetylation to loosen chromatin structure. Given the potential role of retained histones in fertility and early embryonic development, the genomic location of retained nucleosomes is of great interest. However, the ultimate position and mechanisms underlying nucleosome eviction/retention are poorly understood, including several studies utilizing MNase-seq methodologies, but reporting remarkably dissimilar locations. Here, we utilized ATAC-seq to determine the location of retained nucleosomes in mouse sperm and found enrichment at promoters, but also retention at inter- and intragenic regions, and repetitive elements. We further investigated nucleosome eviction/retention by generating pre-meiotic, germ cell specific, conditional knockout mice for the histone acetyltransferase Gcn5, a key histone acetyltransferase. Gcn5cKO germ cells exhibited abnormal chromatin dynamics during spermiogenesis, including diminished nucleosome eviction leading to increased histone retention in sperm. These mice exhibited severe reproductive phenotypes: abnormal sperm production, sperm morphology, and ultimately, male infertility. Our findings demonstrate Gcn5 mediated histone acetylation promotes chromatin accessibility and nucleosome eviction in spermiogenesis, and that loss of histone acetylation leads to defects that disrupt male fertility and potentially, early embryogenesis.
Project description:The mechanisms underlying age-associated memory impairment are not well understood. We have shown that the onset of memory disturbances in the aging brain is associated with altered hippocampal chromatin plasticity. During learning, aged mice display a specific deregulation of histone H4 lysine 12 (H4K12) acetylation. To analyze if deregulated H4K12 acetylation impacts on learning-induced gene-expression required for memory consolidation we performed a high-density oligonucleotide microarray to compare the entire hippocampal gene-expression profile of 3 and 16-month-old mice during memory consolidation.
Project description:We characterize the acetylation of H3K122 for the first time. Towards this we mapped the genomic distribution of H3K122Ac, identified the enzyme introducing H3K122Ac, and addressed the functional contribution H3K122Ac to transcription. We found that H3K122Ac is associated with chromatin marks and genomic regions associated with active transcription and is catalysed by p300/CBP and can be regulated by estrogen signaling in MCF-7. Moreover H3K122Ac stimulates transcription as dermined by in vitro transcription assays ChIP seq study
Project description:Histone acetylation is a ubiquitous hallmark of transcriptional activity, but whether the link is of a causal or consequential nature is still a matter of debate. In this study we resolve this question. Using both immunoblot analysis and chromatin immunoprecipitation-sequencing (ChIP-seq) in S. cerevisiae, we show that the majority of histone acetylation is dependent on transcription. Loss of histone H4 acetylation upon transcription inhibition is partially explained by depletion of histone acetyltransferases (HATs) from gene bodies, implicating transcription in HAT targeting. Despite this, HAT occupancy alone poorly predicts histone acetylation, suggesting that HAT activity is regulated at a step post-recruitment. Collectively, these data show that the majority of histone acetylation is a consequence of RNAPII promoting both the recruitment and activity of histone acetyltransferases.
Project description:Cardiac hypertrophy is characterized by an increase in heart size and profound gene expression changes. Pharmacological histone deacetylase (HDAC) inhibitors attenuate pathological cardiac remodeling and hypertrophic gene expression. Published literature has linked enzymes that mediates histone acetylation to pathogenesis, however, the role of histone acetylation to define hypertrophic gene regulatory events are not well understood. We used chromatin immunoprecipitation (ChIP) coupled with massive parallel sequencing (seq) to comprehensively examine genome-wide histone acetylation changes in a pre-clinical model of pathological cardiac hypertrophy by transverse aortic constricted (TAC). We examined the gene targets conferred by the prototypical HDAC inhibitor Trichostatin A (TSA). TSA induces genome-wide histone acetylation and deacetylation in the heart. Alterations to histone acetylation were found on genes involved in cardiac morphology such as cardiac contraction, collagen deposition, inflammation and extracellular matrix. Gene set enrichment analysis identified NF-kappa B (NFKB), as a transcription factor positively correlated with TAC and negatively correlated with TSA by ChIP-seq. Histone acetylation on the promoters of NKFB target genes was increased, consistent with gene activation. In contrast, the promoters of these genes were deacetylated by TSA in hypertrophic animals and reduced expression of NFKB target genes. Our results suggest a potential mechanism for TSA mediated cardioprotection conferred by histone deacetylation of target genes implicating the importance of inflammation. ChIP-seq profiles for histone acetylation in left ventricles of mice that develop cardiac hypertrophy and treated with HDAC inhibitors were generated by deep sequencing, using Illumina GAIIx.