Project description:Comparison of CBP/p300 gene knock-out, bromodomain inhibitor, and acetyltransferase inhibitors Cmpd-R and A-485 in the same cell line (MEF).
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:Castration resistant prostate cancer (CRPC) remains an incurable disease stage with ineffective treatments options. Here, the androgen receptor (AR) coactivators CBP/p300, which are histone acetyltransferases, were identified as critical mediators of DNA damage repair (DDR) to potentially enhance therapeutic targeting of CRPC. Key findings demonstrate that CBP/p300 expression increases with disease progression and selects for poor prognosis in metastatic disease. CBP/p300 bromodomain inhibition enhances response to standard of care therapeutics. Functional studies, CBP/p300 cistrome mapping, and transcriptome in CRPC revealed that CBP/p300 regulates DDR. Further mechanistic investigation showed that CBP/p300 attenuation via therapeutic targeting and genomic knockdown decreases homologous recombination (HR) factors in vitro, in vivo, and in human prostate cancer (PCa) tumors ex vivo. Similarly, CBP/p300 expression in human prostate tissue correlates with HR factors. Lastly, targeting CBP/p300 impacts HR-mediate repair and patient outcome. Collectively, these studies identify CBP/p300 as drivers of PCa tumorigenesis and lay the groundwork to optimize therapeutic strategies for advanced PCa via CBP/p300 inhibition, potentially in combination with AR-directed and DDR therapies.
Project description:Dysregulated gene expression is one of the most prevalent features in human cancers. Here, we show that most subtypes of acute myeloid leukemia (AML) depend on the aberrant assembly of the MYB transcriptional co-activator complex. By rapid and selective peptidomimetic interference with the binding of CBP/P300 to MYB, but not CREB or MLL1, we find that the leukemic functions of MYB are mediated by CBP/P300-mediated co-activation of a distinct set of transcriptional factor complexes that are aberrantly assembled with MYB in AML cells. This therapeutic remodeling is accompanied by dynamic redistribution of CBP/P300 complexes to genes that control cellular differentiation and growth. Thus, aberrantly organized transcription factor complexes control convergent gene expression programs in AML cells. These findings establish a compelling strategy for pharmacologic reprogramming of oncogenic gene expression that supports its targeting for leukemias and other human cancers caused by dysregulated gene control.
Project description:Reversible epsilon-amino acetylation of lysine residues regulates transcription as well as metabolic flux; however, roles for specific lysine acetyltransferases in skeletal muscle physiology and function remain enigmatic. In this study, we investigated the role of the homologous acetyltransferases p300 and CBP in skeletal muscle transcriptional homeostasis and physiology in adult mice. Mice with skeletal muscle-specific and inducible knockout of p300 and/or CBP were generated by crossing mice with a tamoxifen-inducible Cre recombinase expressed under the human alpha-skeletal actin (HSA) promoter with mice harboring LoxP sites flanking exon 9 of both the Ep300 and Crebbp genes. Knockout was induced at 13-15 weeks of age via oral gavage of tamoxifen. We demonstrate that loss of both p300 and CBP in adult mouse skeletal muscle severely impairs contractile function and results in lethality within one week – a phenotype that is reversed by the presence of a single allele of either p300 or CBP. The loss of muscle function in p300/CBP double knockout mice is paralleled by substantial transcriptional alterations in gene networks central to skeletal muscle contraction and structural integrity. Changes in protein expression patterns, determined by 10-plex TMT labeling, were linked to impaired muscle function also manifest within days (WT mice were compared to day 3 and day 5 knock out mice). Together, these data reveal the requirement of p300 and CBP for the control and maintenance of contractile function and transcriptional homeostasis in skeletal muscle, and ultimately, organism survival. By extension, modulating p300/CBP function holds promise for the treatment of disorders characterized by impaired contractile function in humans.
Project description:Through ChIP-Seq analysis with the Illumina Whole Genome Analyzer, we identify binding sites for P300 (EP300) and CBP (CREBBP) in Human glioblastoma T98G cells that were cell cycle synchronized before and after stimulation. In our analysis, we focused on the identification of genes differentially bound by P300 and CBP. ChIP-seq with P300 and CBP antibodies over 2 timepoints
Project description:We have performed RNA-seq on mouse islets lacking all p300 (p300 KO), all CBP (CBP-null), and one copy of CBP and all p300 (triallelic). The data revealed that p300 and CBP regulate some distinct but largely overlapping genes in islets. This was further confirmed by GO term and transcription factor target analyses, which suggested that these coactivators regulate genes that function similarly and converge to Hnf1a pathway.