Project description:Newly discovered histone lysine acylations increase the functional diversity of nucleosomes well beyond acetylation. Here, we focus on histone butyrylation in the context of sperm cell differentiation. Specifically, we investigate the butyrylation of histone H4 lysine 5 and 8 at gene promoters, where acetylation guides the binding of Brdt, a bromodomain-and-extra-terminal protein, thereby mediating stage-specific gene expression programs. Genome-wide mapping data show that highly active Brdt-bound gene promoters systematically harbour competing histone acetylation and butyrylation marks at H4 K5 and K8. Histone butyrylation, despite acting as a direct stimulator of transcription, competes with acetylation, especially at H4 K5, to prevent Brdt binding. The observed in vivo H4 K5K8 acetylation butyrylation state at active promoters is reproduced in vitro where p300 indistinctly acetylates and butyrylates H4 K5 and K8. Altogether, highly active gene promoter regions are characterized by alternating H4 acetylation and butyrylation sustaining direct gene activation and a dynamic bromodomain binding.
Project description:Changes in acetylation of histone H4 are a common hallmark of cancer cells. In leukemia cells, histone H4 is characterized by loss of K16 mono-acetylation. Bromodomain proteins specifically recognize acetylated lysines and have been used as a target for anti cancer drug, JQ1 and iBET. Although acetylation and de-acetylation of histone H4 have been shown to have big impact in cancer cells, little attention has been focused on histone H4-acetylation at a genome level. To uncover potential epigenetic role of hyper-acetylated histone H4 at a genome-wide level in cancer cell, we generated a novel monoclonal antibody specifically recognizing histone H4 with at least two acetylated lysine residues (H4K5ac+K8ac). At the genome-wide level, hyper-acetylated histone H4 is associated with promoter and regulatory element (active enhancer, eRNA and super enhancer). We show that diacetylation at K5 and K8 of histone H4 co-localizes H3K27ac and BRD2 in the majority of active enhancer and promoters. However BRD2 has a stronger association with H4K5acK8ac. Furthermore we identified two specific chromatin states, which separately contain either H3K27ac or acetylated histone H4. Although JQ1 led to global reduction of BRD2 binding on the chromatin, only local changes of histone H4 multi-acetylation were observed upon BET inhibition by JQ1
Project description:In yeast, histone H3/H4 exchange independent of replication is poorly understood. Here, we analyzed the deposition of histone H3 molecules, synthesized during G1, using a high-density microarray histone exchange assay. While we found that H3 exchange in coding regions requires high levels of transcription, promoters exchange H3 molecules in absence of transcription. In inactive promoters, H3 is deposited predominantly in well-positioned nucleosomes surrounding nucleosome free regions, indicating that some nucleosomes in promoters are dynamic. This could facilitate induction of repressed genes. Importantly, we show that histone H3 K56 acetylation, a replication-associated mark, is also present in replication-independent newly assembled nucleosomes and correlates perfectly with the deposition of new H3. Finally, we found that transcription-dependent incorporation of H3 at promoters is highly dependent on Asf1. Taken together our data underline the dynamic nature of replication-independent nucleosome assembly/disassembly, specify a link to transcription and implicate Asf1 and H3 K56 acetylation. Keywords: ChIP-chip
Project description:Epigenetic regulation of gene expression is tightly controlled by the dynamic modification of histones by chemical groups, the diversity of which has largely expanded over the past decade with the discovery of lysine acylations, catalyzed from acyl-coenzymes A. Here, we investigated the dynamics of lysine acetylation and crotonylation on histones H3 and H4 during mouse spermatogenesis. Lysine crotonylation appeared to be of significant abundance compared to acetylation, particularly on Lys27 of histone H3 (H3K27cr) that accumulates in sperm in a cleaved form of H3. We identified the genomic localization of H3K27cr and studied its effects on transcription compared to the classical active mark H3K27ac at promoters and distal enhancers. The presence of both marks was strongly associated with highest gene expression. Assessment of their co-localization with transcription regulators (SLY, SOX30) and chromatin-binding proteins (BRD4, BORIS and CTCF) indicated systematic highest binding when both active marks were present and different selective binding when present alone at chromatin. H3K27cr and H3K27ac finally mark the building of some sperm super-enhancers. This integrated analysis of omics data provides an unprecedented level of understanding of gene expression regulation by H3K27cr in comparison to H3K27ac, and reveals both synergistic and specific actions of each histone modification.
Project description:Specific histone modifications play important roles in chromatin functions such as activation or repression of gene transcription. These participation must occur as a dynamic process, however, most of histone modification state maps reported to date only provide static pictures linking certain modification with active or silenced states. This study focused on the global histone modification variation that occurs in response to transcriptional reprogramming produced by a physiological perturbation in yeast. We have performed genome-wide chromatin immunoprecipitation analysis for eight specific histone modifications before and after of a saline stress. The most striking change is a quick deacetylation of lysines 9 and 14 of H3 and lysine 8 of H4 associated to repression of genes. Genes that are activated increase the acetylation levels at these same sites, but this acetylation process of activated genes seems minor quantitatively to that of the deacetylation of repressed genes. The observed changes in tri-methylation of lysines 4, 36 and 79 of H3 and also di-methylation of lysine 79 of H3 are much more moderate than those of acetylation. Additionally, we have produced new genome-wide maps for six histone modifications at more than five times higher resolution of previous available data and analyzed for the first time in S. cerevisiae genome wide profiles of two more, acetylation of lysine 8 of H4 and di-methylation of lysine 79 of H3. In this research we have shown that dynamic of acetylation state of histones during activation or repression of transcription is a process much quicker than methylation and therefore the changes produced in the acetylation may affect methylation but the reverse path is not possible. The experiments described in this study compare ChIP with a histone modification antibody to a control ChIP with a core histone antibody. Budding yeast samples were analyzed in exponential growing conditions (YPD) or after 10 minutes of 0.4M NaCl stress. For each experiment 1 or 2 biological replicates were performed.
Project description:To identify candidate enhancer elements we analyzed the distribution of two histone modifications associated with enhancers - H3K4me1 and H3K27ac - and one histone modification associated with active transcription - H4 acetylation.
Project description:Epigenetic regulation of gene expression is tightly controlled by the dynamic modification of histones by chemical groups, the diversity of which has largely expanded over the past decade with the discovery of lysine acylations, catalyzed from acyl-coenzymes A. Here, we investigated the dynamics of lysine acetylation and crotonylation on histones H3 and H4 during mouse spermatogenesis. Lysine crotonylation appeared to be of significant abundance compared to acetylation, particularly on Lys27 of histone H3 (H3K27cr) that accumulates in sperm in a cleaved form of H3. We identified the genomic localization of H3K27cr and studied its effects on transcription compared to the classical active mark H3K27ac at promoters and distal enhancers. The presence of both marks was strongly associated with highest gene expression. Assessment of their co-localization with transcription regulators (SLY, SOX30) and chromatin-binding proteins (BRD4, BORIS and CTCF) indicated systematic highest binding when both active marks were present and different selective binding when present alone at chromatin. H3K27cr and H3K27ac finally mark the building of some sperm super-enhancers. This integrated analysis of omics data provides an unprecedented level of understanding of gene expression regulation by H3K27cr in comparison to H3K27ac, and reveals both synergistic and specific actions of each histone modification.
Project description:Acetylation of histone tails has long been associated with gene activation. Exactly how acetylation regulates gene expression is not fully known. Acetylation events at specific sites or collections of sites on histones elicit distinct outcomes. Here we examine the downstream consequences of histone acetylation by the histone H4 acetyltransferase NuA4 on a genomic scale. Evidence is presented that Bdf1, which is known to bind to acetylated lysine H4 tails in vitro, binds to nucleosomes in vivo and that this binding is dependent upon Esa1, the catalytic subunit of NuA4. Loss of NuA4 results in a coordinate depletion of Bdf1, the transcription complex assembly factor TFIID, and the H2A.Z assembly complex SWR-C at highly acetylated promoter regions. This finding is consistent with known interactions between Bdf1 and TFIID and SWR-C. Loss of Bdf1 results in little or no depletion of TFIID or SWR-C at these promoter regions, possibly due to substitution by the Bdf1 paralog Bdf2. Consistent with this possibility, loss of Bdf1 results in accumulation of Bdf2 at sites normally bound by Bdf1. Together, the findings presented here strengthen the proposed cascade of events whereby nucleosome H4 acetylation by NuA4 at promoters target Bdf1, which then recruits TFIID and SWR-C to assemble the transcription machinery. Keywords: chIP-chip, histone acetylation, transcription factor recruitment
Project description:To identify candidate enhancer elements we analyzed the distribution of two histone modifications associated with enhancers - H3K4me1 and H3K27ac - and one histone modification associated with active transcription - H4 acetylation. ChIP-seq for H3K4me1, H3K27ac and H4ac, and input DNA controls, from 2 cell types (DCs & fibroblasts) under 2 conditions (unstimulated & stimulated)
Project description:The energetic costs of duplicating chromatin are large and therefore likely depend on nutrient sensing checkpoints and metabolic inputs. By studying chromatin modifiers regulated by epithelial growth factor, we identified histone acetyltransferase 1 (HAT1) as an induced gene that enhances proliferation through coordinating histone production, acetylation and glucose metabolism. In addition to its canonical role as a cytoplasmic histone H4 acetyltransferase, we isolated a HAT1-containing complex bound specifically at promoters of H4 genes. HAT1-dependent transcription of H4 genes required an acetate-sensitive promoter element. HAT1 expression was critical for S-phase progression and maintenance of H3 lysine 9 acetylation at proliferation-associated genes, including histone genes. Therefore, these data describe a feed-forward circuit whereby HAT1 captures acetyl-groups on nascent histones and drives H4 production by chromatin binding to support chromatin replication and acetylation. These findings have important implications for human disease, since high HAT1 levels associate with poor outcomes across multiple cancer types.