ABSTRACT: We used quantitative proteomics to characterize the p300-regulated lysine 2-hydroxyisobutyrylome in wild type (WT) and p300 knockout (KO) cells.
Project description:We used quantitative proteomics to characterize the p300-regulated lysine crotonylome in wild type (WT) and p300 knockout (KO) cells.
Project description:We performed genome-wide expression profiling analysis to define the genes underlying the synthetic-lethal relationship between CBP and p300. We extracted 1,936 genes whose expression levels changed >2-fold upon p300-knockdown (KD) in CBP-KO cells, or upon CBP-KD in p300-KO cells, but not in either KD in wild-type cells Gene expression profile in human lung H1299, H1299 CBP KO, H1299 p300KO cells was measured at 48 hours after transfection of siNT, siCBP or sip300. Two independent experiments were performed at each time (48 hours).
Project description:The transcriptional co-activator and acetyltransferase p300 is required for fundamental cellular processes, including differentiation and growth. Here, we report that p300 forms phase separated condensates in the cell nucleus. The phase separation ability of p300 is regulated by autoacetylation and relies on its catalytic core components, including the HAT domain, the autoinhibition loop, and bromodomain. p300 condensates sequester chromatin components, such as histone H3 tail and DNA, and are amplified through binding of p300 to the nucleosome. The catalytic HAT activity of p300 is decreased due to occlusion of the active site in the phase separated droplets, a large portion of which co-localizes with chromatin regions enriched in H3K27me3. Our findings suggest a model in which p300 condensates can act as a storage pool of the protein with reduced HAT activity, allowing p300 to be compartmentalized and concentrated at poised or repressed chromatin regions.
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:Lysine 2-hydroxyisobutyrylation (Khib) is an evolutionary conserved and widespread protein posttranslational modification (PTM) that has diverse cellular functions. Recently, it has been demonstrated that Khib can be regulated by p300 and Tip60. Although the specific Khib substrates mediated by p300 has been revealed, how Tip60 regulates diverse cellular processes through the Khib pathway and the different roles between Tip60 and p300 towards regulating Khib remains largely unknown, which hinders our understanding of the mechanisms by which this modification exerts its biological functions. Here we report the first Khib proteome mediated by Tip60. A total of 2999 unique Khib sites on 956 proteins were identified. Among them, 397 Khib sites from 322 proteins presented only in Tip60 overexpressing cells and 10 Khib sites increased greater than 2-fold in response of Tip60 overexpression, indicating that Tip60 significantly affected global Khib . Surprisingly, only 5 of the 407 Tip60-targeted Khib sites overlapping with the 149 known p300-targeted Khib sites, indicating that Tip60 and p300 have different substrate preference for Khib. In addition, the Khib substrates regulated by Tip60 are deeply involved in processes such as mRNA translation and protein co-folding, and some are associated with diseases such as Parkinson. Together, this study reveals the Khib substrates in response to Tip60, which elucidates the role of Tip60 in regulating various cellular processes through Khib pathway, and provides new insights into functional mechanism of Tip60.
Project description:Rubinstein-Taybi syndrome (RSTS) is a complex autosomal-dominant disease characterized by mental and growth retardation and skeletal abnormalities. A majority of the individuals diagnosed with RSTS carry heterozygous mutation in the gene CREBBP, but a small percentage of cases are caused by mutations in EP300. To investigate the contribution of p300 to RSTS pathoetiology, we carried out a comprehensive and multidisciplinary characterization of p300+/- mice. These mice exhibited facial abnormalities and impaired growth, two traits associated to RSTS in humans. We also observed abnormal gait, reduced swimming speed, enhanced anxiety in the elevated plus maze, and mild cognitive impairment during the transfer task in the water maze. These analyses demonstratethat p300+/- mice exhibit phenotypes that are reminiscent of neurological traits observed in RSTS patients, but their comparison with previous studies on CBP deficient strains also indicate that, in agreement with the most recent findings in human patients, the activity of p300 in cognition is likely less relevant or more susceptible to compensation than the activity of CBP. To identify those genes whose expression was altered in the hippocampus of p300 deficient mutants, we performed a gene profiling analysis of hippocampal tissue using high-density oligonucleotide microarrays. Experiment Overall Design: We obtained triplicate samples containing total RNA from the hippocampi of four 3-month old females of either genotype (in total 12 p300+/- mice and 12 wild type littermates were used in the experiment).
Project description:The completion of the Plasmodium falciparum clone 3D7 genome provides a basis on which to conduct comparative proteomics studies of this human pathogen. Here, we applied a high-throughput proteomics approach to identify new potential drug and vaccine targets and to better understand the biology of this complex protozoan parasite. We characterized four stages of the parasite life cycle (sporozoites, merozoites, trophozoites and gametocytes) by multidimensional protein identification technology. Functional profiling of over 2,400 proteins agreed with the physiology of each stage. Unexpectedly, the antigenically variant proteins of var and rif genes, defined as molecules on the surface of infected erythrocytes, were also largely expressed in sporozoites. The detection of chromosomal clusters encoding co-expressed proteins suggested a potential mechanism for controlling gene expression. Keywords: ordered
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:Determining the spatial and temporal activity patterns of enhancers remains a challenge in the functional annotation of the human genome. Here, we performed genome-wide mapping of tissue-specific in vivo binding sites for the enhancer-associated protein p300 and assessed in transgenic mice the utility of this information in identifying enhancers and predicting their activity patterns. Chromatin immunoprecipitation followed by massively-parallel sequencing was used to identify p300-enriched sites in mouse embryonic day 11.5 (e11.5) forebrain, midbrain, and limb. In total, 4,686 genomic regions were enriched for p300 in vivo in at least one of these tissues. To determine whether p300-binding accurately identifies enhancers and predicts their activity patterns, we tested 86 of these regions in a transgenic mouse enhancer assay at e11.5. In 88% of the cases, p300-enriched sequences were reproducible enhancers, and in 91% of these cases p300 enrichment correctly predicted the tissues in which in vivo activity was observed. Our results indicate that in vivo mapping of p300 binding to non-coding DNA is a highly effective means for identifying enhancers and their associated spatial activity patterns. Examination of p300 binding in 3 embryonic stage 11.5 mouse tissues
Project description:Mitochondrial dysfunction is one of many key factors in the etiology of alcoholic liver disease (ALD). Lysine acetylation is known to regulate numerous mitochondrial metabolic pathways and recent reports demonstrate that alcohol-induced protein acylation negatively impacts these processes. To identify regulatory mechanisms attributed to alcohol-induced protein post-translational modifications, we employed a model of alcohol consumption within the context of wild type (WT), sirtuin 3 knockout (SIRT3 KO), and sirtuin 5 knockout(SIRT5 KO) mice to manipulate hepatic mitochondrial protein acylation. Mitochondrial fractions were examined by label-free quantitative HPLC-MS/MS to reveal competition between lysine acetylation and succinylation. A class of proteins defined as “differential acyl switching proteins” demonstrate select sensitivity to alcohol-induced protein acylation. A number of these proteins reveal saturated lysine-site occupancy, suggesting a significant level of differential stoichiometry in the setting of ethanol consumption. We hypothesize that ethanol downregulates numerous mitochondrial metabolic pathways through differential acyl switching proteins.