Project description:Organisms respond to mitochondrial stress by activating multiple defense pathways including the mitochondrial unfolded protein response (UPRmt). However, how different layers of UPRmt regulators are orchestrated to transcriptionally activate the stress responses remains largely unknown. Here we identified CBP-1, the worm ortholog of the mammalian acetyltransferases CBP/p300, as an essential regulator for UPRmt activation, as well as for mitochondrial stress-induced immune response, amyloid-β aggregation reduction and lifespan extension in Caenorhabditis elegans. Mechanistically, CBP-1 acts downstream of histone demethylases, JMJD-1.2/JMJD-3.1, and upstream of UPRmt transcription factors including ATFS-1, to systematically induce a broad spectrum of UPRmt genes and execute multiple beneficial functions. In mouse and human populations, transcript levels of CBP/p300 positively correlate with UPRmt transcripts and longevity. Furthermore, CBP/p300 inhibition disrupts, while forced expression of p300 is sufficient to activate, the UPRmt in mammalian cells. These results highlight an evolutionarily conserved mechanism that determines mitochondrial stress response, and promotes health and longevity through CBP/p300.
Project description:The CH1 protein interaction domain of the transcriptional coactivators p300 and CBP is thought to interact with HIF-1alpha and this interaction is thought to be critical to the expression of HIF-1alpha target genes in response to hypoxia. To test the requirement of the CH1 domain for gene expression in response to hypoxia, rimary mouse embryonic fibroblasts (MEFs) were generated from C57Bl/6x129/Sv F2 e14.5 embryos that contain a deletion in the CH1 domain of three of four alleles of CBP and p300. The remaining allele of p300 or CBP was a conditional knock out allele. Control MEFs with only a single conditional knockout allele of p300 or CBP were also generated. At passage 3 MEFs were infected with Cre Adenovirus and grown until they had expanded at least 100 fold. Subconfluent MEFs were treated with 21% oxygen (normoxia) or 0.1% oxygen (hypoxia) with 5% carbon dioxide at 37 C in a humid chamber for 6hrs. At the start of treatment, medium was removed and replaced with medium (DMEM+10% FBS+pen-strep+ l-glu) that had been preequilibrated overnight in normoxia or hypoxia as appropriate. Immediately after treatment, cells were lysed in Trizol for RNA extraction. 12 samples; 4 genotypes [CBP+/flox (flox1), p300 +/flox (flox2), CBP CH1/flox;p300 CH1/CH1 (triCH1flox1),CBP CH1/CH1;p300 CH1/flox (triCH1flox2)] , 2 treatments (normoxia and hypoxia).
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:The CH1 protein interaction domain of the transcriptional coactivators p300 and CBP is thought to interact with HIF-1alpha and this interaction is thought to be critical to the expression of HIF-1alpha target genes in response to hypoxia. Trichostatin A (TSA), an inhibitor of histone deacetylases, has been reported to repress the expression of HIF-1alpha target genes. To test the requirement of the CH1 domain and TSA for gene expression in response to dipyridyl (a hypoxia mimetic), primary mouse embryonic fibroblasts (MEFs) were generated from C57Bl/6x129/Sv F2 e14.5 embryos that contain a deletion in the CH1 domain of three of four alleles of CBP and p300. The remaining allele of p300 or CBP was a conditional knock out allele. Control MEFs with only a single conditional knockout allele of p300 or CBP were also generated. At passage 3 MEFs were infected with Cre Adenovirus and grown until they had expanded at least 100 fold. Subconfluent MEFs were treated with ethanol vehicle or 100ng/ml TSA with 5% carbon dioxide at 37 C in a humid chamber for 30 min., followed by ethanol vehicle or 100 umdipyridyl (DP) for an additional 3hrs. Immediately after treatment, cells were lysed in Trizol for RNA extraction.
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: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:Histone acetyltransferases (HATs) GCN5/PCAF and CBP/p300 are transcription coactivators. However, how these HATs regulate ligand-induced nuclear receptor target gene expression remains unclear. Here we show in mouse embryonic fibroblasts (MEFs), deletion of GCN5/PCAF specifically eliminates acetylation on H3K9 (H3K9Ac) while deletion of CBP/p300 selectively reduces acetylation on H3K18 and H3K27 (H3K18/27Ac). Treating MEFs with a specific ligand for nuclear receptor PPARdelta induces sequential increases of H3K18/27Ac and H3K9Ac on the promoter of PPARdelta target gene Angptl4, which correlates with a robust ligand-induced Angptl4 expression. Inhibiting transcription elongation blocks ligand-induced H3K9Ac but not H3K18/27Ac on Angptl4 promoter. Finally, we show CBP/p300 and their HAT activities are required, while GCN5/PCAF and H3K9Ac are dispensable, for ligand-induced PPARdelta target gene expression in MEFs. These results highlight the substrate and site specificities of HATs in cells, and suggest that GCN5/PCAF- and CBP/p300-mediated histone acetylations play distinct roles in regulating ligand-induced nuclear receptor target gene expression. PCAF and GCN5 have some redundant function. To identify PCAF/GCN5-regulated genes, immortalized MEFs with PCAF knockout and GCN5 conditional knockout were infected with retroviruses expressing either Cre recombinase or vector alone. We prepared duplicated RNAs from either vector or Cre infected cells (PCAF-/-;GCN5+/- or PCAF-/-;GCN5+/-) and RNAs from either Vector or Cre infected the other independently immortalized cells for 6 affymetrix microarray.
Project description:Mutation of rod photoreceptor-enriched transcription factors is a major cause of inherited blindness. We identified the orphan nuclear hormone receptor ERRβ as selectively expressed in rod photoreceptors. Overexpression of ERRβ induces expression of rod-specific genes in retinas of both wildtype and in Nrl-/- mice, which lack rod photoreceptors. Mutation of ERRβ results in dysfunction and degeneration of rods, while inverse agonists of ERRβ trigger rapid rod degeneration, which is rescued by constitutively active mutants of ERRβ. ERRβ coordinates expression of multiple genes that are rate-limiting regulators of ATP generation and consumption in photoreceptors. Furthermore, enhancing ERRβ activity rescues photoreceptor defects that result from loss of the photoreceptor-specific transcription factor Crx. Our findings demonstrate that ERRβ is a critical regulator of rod photoreceptor function and survival, and suggest that ERRβ agonists may be useful in the treatment of certain retinal dystrophies. Affymetrix MOE430 microarrays were used to analyze the expression patterns of P21 mouse retinal tissues. The results were compared across the variable of Genotype, specifically ERRβ knockout versus wildtype.