Enhancers are Activated by p300/CBP Activity-Dependent PIC Assembly, RNAPII Recruitment and Pause Release [ATAC-Seq]
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ABSTRACT: The metazoan-specific acetyltransferase p300/CBP is involved in activating signalinduced, enhancer-mediated transcription of cell-type-specific genes. However, the global kinetics and mechanisms of p300/CBP activity-dependent transcription activation remain poorly understood. We performed genome-wide, time-resolved analyses to show that enhancers and super-enhancers are dynamically activated through p300/CBP-catalyzed acetylation, deactivated by the opposing deacetylase activity, and kinetic acetylation directly contributes to maintaining cell identity at very rapid timescales. The acetyltransferase activity is dispensable for the recruitment of p300/CBP and transcription factors, but essential for promoting the recruitment of TFIID and RNAPII at virtually all enhancers and enhancer-regulated genes. This identifies pre-initiation complex assembly as a dynamically controlled step in the transcription cycle and reveals p300/CBP-catalyzed acetylation as the signal that specifically promotes transcription initiation at enhancer-regulated genes. We propose that p300/CBP activity uses a ‘recruit-and-release’ mechanism to simultaneously promote RNAPII recruitment and pause release, and thereby, enables kinetic activation of enhancer-mediated transcription.
Project description:The metazoan-specific acetyltransferase p300/CBP is involved in activating signalinduced, enhancer-mediated transcription of cell-type-specific genes. However, the global kinetics and mechanisms of p300/CBP activity-dependent transcription activation remain poorly understood. We performed genome-wide, time-resolved analyses to show that enhancers and super-enhancers are dynamically activated through p300/CBP-catalyzed acetylation, deactivated by the opposing deacetylase activity, and kinetic acetylation directly contributes to maintaining cell identity at very rapid timescales. The acetyltransferase activity is dispensable for the recruitment of p300/CBP and transcription factors, but essential for promoting the recruitment of TFIID and RNAPII at virtually all enhancers and enhancer-regulated genes. This identifies pre-initiation complex assembly as a dynamically controlled step in the transcription cycle and reveals p300/CBP-catalyzed acetylation as the signal that specifically promotes transcription initiation at enhancer-regulated genes. We propose that p300/CBP activity uses a ‘recruit-and-release’ mechanism to simultaneously promote RNAPII recruitment and pause release, and thereby, enables kinetic activation of enhancer-mediated transcription.
Project description:The metazoan-specific acetyltransferase p300/CBP is involved in activating signalinduced, enhancer-mediated transcription of cell-type-specific genes. However, the global kinetics and mechanisms of p300/CBP activity-dependent transcription activation remain poorly understood. We performed genome-wide, time-resolved analyses to show that enhancers and super-enhancers are dynamically activated through p300/CBP-catalyzed acetylation, deactivated by the opposing deacetylase activity, and kinetic acetylation directly contributes to maintaining cell identity at very rapid timescales. The acetyltransferase activity is dispensable for the recruitment of p300/CBP and transcription factors, but essential for promoting the recruitment of TFIID and RNAPII at virtually all enhancers and enhancer-regulated genes. This identifies pre-initiation complex assembly as a dynamically controlled step in the transcription cycle and reveals p300/CBP-catalyzed acetylation as the signal that specifically promotes transcription initiation at enhancer-regulated genes. We propose that p300/CBP activity uses a ‘recruit-and-release’ mechanism to simultaneously promote RNAPII recruitment and pause release, and thereby, enables kinetic activation of enhancer-mediated transcription.
Project description:The acetyltransferases CBP and p300 are multifunctional transcriptional co-activators; however, their acetylation targets, site-specific acetylation kinetics, and function in proteome regulation are incompletely understood. We combined quantitative proteomics with novel CBP/p300-specific catalytic inhibitors, bromodomain inhibitor, and gene knockout to show that CBP/p300 acetylates thousands of sites, including signature histone sites, as well as a multitude of sites on signaling effectors and enhancer-associated transcriptional regulators. Kinetic analysis identified a subset of CBP/p300-regulated sites with very rapid (<30min) acetylation turnover, revealing a dynamic balance between acetylation and deacetylation. Quantification of acetylation, mRNA, and protein abundance after CBP/p300 inhibition reveals a kinetically competent network of gene expression that strictly depends on CBP/p300-catalyzed rapid acetylation. Collectively, our in-depth acetylome analyses reveal systems attributes of CBP/p300 targets, and the resource dataset provides a framework for investigating CBP/p300 functions, as well as for understanding the impact of small molecule inhibitors targeting its catalytic and bromodomain activities.
Project description:The acetyltransferases CBP and p300 are multifunctional transcriptional co-activators; however, their acetylation targets, site-specific acetylation kinetics, and function in proteome regulation are incompletely understood. We combined quantitative proteomics with novel CBP/p300-specific catalytic inhibitors, bromodomain inhibitor, and gene knockout to show that CBP/p300 acetylates thousands of sites, including signature histone sites, as well as a multitude of sites on signaling effectors and enhancer-associated transcriptional regulators. Kinetic analysis identified a subset of CBP/p300-regulated sites with very rapid (<30min) acetylation turnover, revealing a dynamic balance between acetylation and deacetylation. Quantification of acetylation, mRNA, and protein abundance after CBP/p300 inhibition reveals a kinetically competent network of gene expression that strictly depends on CBP/p300-catalyzed rapid acetylation. Collectively, our in-depth acetylome analyses reveal systems attributes of CBP/p300 targets, and the resource dataset provides a framework for investigating CBP/p300 functions, as well as for understanding the impact of small molecule inhibitors targeting its catalytic and bromodomain activities.
Project description:Chromatin features are widely used for genome-scale mapping of enhancers. However, discriminating active enhancers from other cis-regulatory elements, predicting enhancer strength, and identifying their target genes remains challenging. Here we establish histone H2B N-terminus multisite lysine acetylation (H2BNTac) as a genuine signature of active enhancers. H2BNTac prominently marks candidate active enhancers and a subset of promoters and discriminates them from ubiquitously active promoters. Two mechanisms afford the distinct H2BNTac specificity. (1) Unlike H3K27ac, H2BNTac is specifically catalyzed by CBP/p300. (2) H2A-H2B, but not H3-H4, are rapidly exchanged through transcription-induced nucleosome remodeling. H2BNTac-positive candidate enhancers show a high validation rate in orthogonal enhancer activity assays, and a vast majority of endogenously active enhancers are marked by H2BNTac and H3K27ac. Notably, H2BNTac intensity predicts enhancer strength and outperforms the current state-of-the-art models in predicting CBP/p300 target genes. These findings have broad implications for generating fine-grained enhancer maps and modeling CBP/p300-dependent gene regulation.
Project description:The clustered homeobox proteins play crucial roles in development, hematopoiesis and leukemia yet the targets they regulate and their mechanisms of action are poorly understood. Here, we identified the binding sites for Hoxa9 and the Hox cofactor Meis1 on a genome-wide level and profiled their associated epigenetic modifications and transcriptional targets. Hoxa9 and the Hox cofactor Meis1 co-bind at hundreds of highly evolutionarily-conserved sites, most of which are distant from transcription start sites. These sites show high levels of histone H3K4 monomethylation and CBP/P300 binding characteristic of enhancers. Furthermore, a subset of these sites shows enhancer activity in transient transfection assays. Many Hoxa9 and Meis1 binding sites are also bound by PU.1 and other lineage-restricted transcription factors previously implicated in establishment of myeloid enhancers. Conditional Hoxa9 activation is associated with CBP/P300 recruitment, histone acetylation and transcriptional activation of a network of proto-oncogenes including Erg, Flt3, Lmo2, Myb and Sox4. Collectively this work suggests that Hoxa9 regulates transcription by interacting with enhancers of genes important for hematopoiesis and leukemia. To identify the genome-wide binding sites for Hoxa9 and the Hox cofactor Meis1
Project description:Genome-wide distribution of histone H3K18 and H3K27 acetyltransferases, Crebbp (CBP) and Ep300 (p300), is used to map enhancers and promoters, but whether these elements functionally require CBP/p300 remains largely uncertain. We investigated this relationship by comparing genomic CBP recruitment with gene expression in wild type and CBP/p300 double-knockout fibroblasts. ChIP-seq revealed nearby CBP recruitment for 20 percent of constitutively expressed genes, but surprisingly, three-quarters of these were unaffected or slightly activated by CBP/p300 deletion. Computationally defined enhancer-promoter-units (EPUs) having a CBP peak within two kilobases of the enhancer-like element provided better predictive value, with CBP/p300 deletion attenuating expression of 40 percent of such EPU assigned constitutively expressed genes. We next examined signaling-responsive (Hypoxia Inducible Factor) gene expression and CBP recruitment, and found that 97 percent of inducible genes were within 50 kilobases of an inducible CBP peak, and 70 percent of these required CBP/p300 for full inducible expression. Unexpectedly however, most inducible CBP peaks occurred near signal-nonresponsive genes. 12 samples, 3 each wild type and CBP/p300 null treated for 3hrs with 100uM dipyridyl orethanol vehicle.
Project description:CBP/p300 are transcription co-activators whose binding is a signature of enhancers, cis-regulatory elements that control patterns of gene expression in multicellular organisms. Active enhancers produce bi-directional enhancer RNAs (eRNAs) and display CBP/p300 dependent histone acetylation. Here, we demonstrate that CBP binds directly to RNAs in vivo and in vitro. RNAs bound to CBP in vivo include a large number of eRNAs. Using steady-state histone acetyltransferase (HAT) assays we show that an RNA binding region in the HAT domain of CBP—a regulatory motif unique to CBP/p300—allows RNA to stimulate CBP’s HAT activity. At enhancers where CBP interacts with eRNAs, stimulation manifests in RNA-dependent changes in the histone acetylation mediated by CBP, such as H3K27ac, and by corresponding changes in gene expression. By interacting directly with CBP, eRNAs contribute to the unique chromatin structure at active enhancers, which in turn is required for regulation of target genes.
Project description:Genome-wide distribution of histone H3K18 and H3K27 acetyltransferases, Crebbp (CBP) and Ep300 (p300), is used to map enhancers and promoters, but whether these elements functionally require CBP/p300 remains largely uncertain. We investigated this relationship by comparing genomic CBP recruitment with gene expression in wild type and CBP/p300 double-knockout fibroblasts. ChIP-seq revealed nearby CBP recruitment for 20 percent of constitutively expressed genes, but surprisingly, three-quarters of these were unaffected or slightly activated by CBP/p300 deletion. Computationally defined enhancer-promoter-units (EPUs) having a CBP peak within two kilobases of the enhancer-like element provided better predictive value, with CBP/p300 deletion attenuating expression of 40 percent of such EPU assigned constitutively expressed genes. We next examined signaling-responsive (Hypoxia Inducible Factor) gene expression and CBP recruitment, and found that 97 percent of inducible genes were within 50 kilobases of an inducible CBP peak, and 70 percent of these required CBP/p300 for full inducible expression. Unexpectedly however, most inducible CBP peaks occurred near signal-nonresponsive genes. eight samples total; Two wild type and two CBP null primary mouse embryonic fibroblast (MEF) lines, each treated with 100uM 2,2-dipyridyl or ethanol vehicle for 2 hours
Project description:Regulation of RNA Polymerase II (Pol2) elongation in the promoter proximal region is an important and ubiquitous control point for gene expression in metazoans. We report that transcription of the adenovirus 5 E4 region is regulated during the release of paused Pol2 into productive elongation by recruitment of the super elongation complex (SEC), dependent on promoter H3K18/27 acetylation by CBP/p300. We also establish that this is a general transcriptional regulatory mechanism that applies to ~6% of expressed protein-coding genes in primary human airway epithelial cells. We observed that a homeostatic mechanism maintains promoter, but not enhancer H3K18/27ac in response to extensive inhibition of CBP/p300 acetyl transferase activity by the highly specific small molecule inhibitor A-485. Further, our results suggest a function for BRD4 association at enhancers in regulating paused Pol2 release at nearby promoters. Taken together, our results uncover processes regulating transcriptional elongation by promoter region histone H3 acetylation and homeostatic maintenance of promoter, but not enhancer, H3K18/27ac in response to inhibition of CBP/p300 acetyl transferase activity.