Project description:In the article "Fra-1 regulates its target genes via binding to remote enhancers without exerting major control on chromatin architecture in triple negative breast cancers" by Bejjani et al., we mapped p300/CBP binding sites in MDA-MB-231 cells transfected with a control siRNA or a siRNA directed against Fra-1(FOSL1) to study whether Fra-1 can modulate p300/CBP recruitment on MDA-MB-231 genome
Project description:In the article "Fra-1 regulates its target genes via binding to remote enhancers without exerting major control on chromatin architecture in triple negative breast cancers" by Bejjani et al., we mapped epigenetic marks (H3K4me1, H3K4me3, H3K27ac), p300/CBP, PolII and CTCF to characterize the binding sites of Fra-1 and Fra-2 on MDA-MB-231 genome. Data for Fra-1 and Fra-2 ChIP-seq are available on GEO database, accession number GSE132098 (Tolza et al., 2019, MCR 17, 1999-2014)
Project description:Histone acetylation is important for the activation of gene transcription but little is known about its direct ‘read/write’ mechanisms. Here, we report cryo-electron microscopy structures in which a p300/CBP multidomain monomer recognizes histone H4 N-terminal tail (NT) acetylation (ac) in a nucleosome and acetylates non-H4 histone NTs within the same nucleosome. p300/CBP not only recognized H4NTac via the bromodomain pocket responsible for ‘reading’, but also interacted with the DNA minor grooves via the outside of that pocket. This directed the catalytic center of p300/CBP to one of the non-H4 histone NTs. The primary target that p300 ‘writes’ by ‘reading’ H4NTac was H2BNT, and H2BNTac promoted H2A-H2B dissociation from the nucleosome. We propose a model in which p300/CBP ‘replicates’ histone NT acetylation within the H3-H4 tetramer to inherit epigenetic storage, and ‘transcribes’ it from the H3-H4 tetramer to the H2B-H2A dimers to activate context-dependent gene transcription through local nucleosome destabilization.
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:Prostate cancer is driven by oncogenic transcription factor enhanceosomes comprising chromatin and epigenetic regulators. The lysine acetyltransferases p300 and CBP are key cofactors that activate enhancers through histone acetylation. Here, we identify p300/CBP-mediated multisite acetylation of the histone H2B N-terminus (H2BNTac) as a defining feature of oncogenic enhanceosomes in androgen receptor (AR)-positive prostate cancer. p300/CBP are essential for AR and ERG transcriptional activity, and their dual degradation eliminates H2BNTac and H3K27ac marks at hyperactive enhancers more effectively than targeting either paralog or bromodomains alone. Cytotoxicity profiling across >900 cell lines revealed that tumors with high H2BNTac, including AR-positive prostate cancer, are selectively dependent on p300/CBP. In preclinical models, systemic p300/CBP degradation inhibited tumor growth, synergized with AR antagonists, and showed no evident toxicity. These findings position H2BNTac as a key epigenetic marker of enhancer addiction and support dual p300/CBP degradation as a promising therapy for enhancer-driven cancers.
Project description:Prostate cancer is driven by oncogenic transcription factor enhanceosomes comprising chromatin and epigenetic regulators. The lysine acetyltransferases p300 and CBP are key cofactors that activate enhancers through histone acetylation. Here, we identify p300/CBP-mediated multisite acetylation of the histone H2B N-terminus (H2BNTac) as a defining feature of oncogenic enhanceosomes in androgen receptor (AR)-positive prostate cancer. p300/CBP are essential for AR and ERG transcriptional activity, and their dual degradation eliminates H2BNTac and H3K27ac marks at hyperactive enhancers more effectively than targeting either paralog or bromodomains alone. Cytotoxicity profiling across >900 cell lines revealed that tumors with high H2BNTac, including AR-positive prostate cancer, are selectively dependent on p300/CBP. In preclinical models, systemic p300/CBP degradation inhibited tumor growth, synergized with AR antagonists, and showed no evident toxicity. These findings position H2BNTac as a key epigenetic marker of enhancer addiction and support dual p300/CBP degradation as a promising therapy for enhancer-driven cancers.
Project description:C4-2B prostate cancer cells were transfected with siRNA against a non-specific (NS) sequence, siRNA specifically targeting EP300, or siRNA specifically targeting CREBBP. We tested the hypothesis that their exists different subgroups of genes that are preferentially affected by p300 or CBP depletion.