BRD4 loading at the transcription start site mediates pause-release and underlies the disproportionate transcriptional response to BET bromodomain inhibition
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE70450 | GEO | 2023/01/06
REPOSITORIES: GEO
Similar Datasets
Project description:BET bromodomain inhibition (BETi) abrogates cancer cell growth by disrupting oncogenic gene expression. BRD4 loading at enhancers has been suggested to mediate pause-release and underlie the selective transcriptional response to BETi. Here, we utilized GRO-seq coupled with ChIP-seq to assess the association between gene control elements and the transcriptional response to BETi. Genes immediately down-regulated by BETi display a marked pause-release defect with a minimal impact on transcript elongation within the gene body. Surprisingly, we find that BRD4 at super-enhancers does not render its associated genes or enhancer RNAs preferentially sensitive to BETi. In contrast, disproportionate loading of BRD4 at transcription start sites (TSS) correlates with the transcriptional response to BETi. Moreover, BRD4 loading at TSSs, but not enhancers, is associated with enhanced promoter-proximal pausing following BETi. Our findings stress a mechanistic role of promoter-associated BRD4 in pause-release and suggest that BRD4 loading at the TSS drives the selective transcriptional response to BETi.
2023-01-06 | GSE70449 | GEO
Project description:BET bromodomain inhibition (BETi) abrogates cancer cell growth by disrupting oncogenic gene expression. BRD4 loading at enhancers has been suggested to mediate pause-release and underlie the selective transcriptional response to BETi. Here, we utilized GRO-seq coupled with ChIP-seq to assess the association between gene control elements and the transcriptional response to BETi. Genes immediately down-regulated by BETi display a marked pause-release defect with a minimal impact on transcript elongation within the gene body. Surprisingly, we find that BRD4 at super-enhancers does not render its associated genes or enhancer RNAs preferentially sensitive to BETi. In contrast, disproportionate loading of BRD4 at transcription start sites (TSS) correlates with the transcriptional response to BETi. Moreover, BRD4 loading at TSSs, but not enhancers, is associated with enhanced promoter-proximal pausing following BETi. Our findings stress a mechanistic role of promoter-associated BRD4 in pause-release and suggest that BRD4 loading at the TSS drives the selective transcriptional response to BETi.
2023-01-06 | GSE70448 | GEO
Project description:BET bromodomain inhibition (BETi) abrogates cancer cell growth by disrupting oncogenic gene expression. BRD4 loading at enhancers has been suggested to mediate pause-release and underlie the selective transcriptional response to BETi. Here, we utilized GRO-seq coupled with ChIP-seq to assess the association between gene control elements and the transcriptional response to BETi. Genes immediately down-regulated by BETi display a marked pause-release defect with a minimal impact on transcript elongation within the gene body. Surprisingly, we find that BRD4 at super-enhancers does not render its associated genes or enhancer RNAs preferentially sensitive to BETi. In contrast, disproportionate loading of BRD4 at transcription start sites (TSS) correlates with the transcriptional response to BETi. Moreover, BRD4 loading at TSSs, but not enhancers, is associated with enhanced promoter-proximal pausing following BETi. Our findings stress a mechanistic role of promoter-associated BRD4 in pause-release and suggest that BRD4 loading at the TSS drives the selective transcriptional response to BETi.
2023-01-06 | GSE70447 | GEO
Project description:BRD4 loading at the transcription start site mediates pause-release and underlies the disproportionate transcriptional response to BET bromodomain inhibition
| PRJNA288701 | ENA
Project description:Distal enhancers characterized by the H3K4me(1) mark play critical roles in developmental and transcriptional programs. However, potential roles of specific distal regulatory elements in regulating RNA polymerase II (Pol II) promoter-proximal pause release remain poorly investigated. Here, we report that a unique cohort of jumonji C-domain-containing protein 6 (JMJD6) and bromodomain-containing protein 4 (Brd4) cobound distal enhancers, termed anti-pause enhancers (A-PEs), regulate promoter-proximal pause release of a large subset of transcription units via long-range interactions. Brd4-dependent JMJD6 recruitment on A-PEs mediates erasure of H4R3me(2(s)), which is directly read by 7SK snRNA, and decapping/demethylation of 7SK snRNA, ensuring the dismissal of the 7SK snRNA/HEXIM inhibitory complex. The interactions of both JMJD6 and Brd4 with the P-TEFb complex permit its activation and pause release of regulated coding genes. The functions of JMJD6/ Brd4-associated dual histone and RNA demethylase activity on anti-pause enhancers have intriguing implications for these proteins in development, homeostasis, and disease.
| S-EPMC3886918 | biostudies-literature
Project description:Myogenic differentiation proceeds through a highly coordinated cascade of gene activation that necessitates epigenomic changes in chromatin structure. Using a screen of small molecule epigenetic probes we identified three compounds which inhibited myogenic differentiation in C2C12 myoblasts; (+)-JQ1, PFI-1, and Bromosporine. These molecules target Bromodomain and Extra Terminal domain (BET) proteins, which are epigenetic readers of acetylated histone lysine tail residues. BETi-mediated anti-myogenic effects were also observed in a model of MYOD1-mediated myogenic conversion of human fibroblasts, and in primary mouse and human myoblasts. All three BET proteins BRD2, BRD3 and BRD4 exhibited distinct and dynamic patterns of protein expression over the course of differentiation without concomitant changes in mRNA levels, suggesting that BET proteins are regulated at the post-transcriptional level. Specific BET protein knockdown by RNA interference revealed that BRD4 was required for myogenic differentiation, whereas BRD3 down-regulation resulted in enhanced myogenic differentiation. ChIP experiments revealed a preferential binding of BRD4 to the Myog promoter during C2C12 myoblast differentiation, co-incident with increased levels of H3K27 acetylation. These results have identified an essential role for BET proteins in the regulation of skeletal myogenesis, and assign distinct functions to BRD3 and BRD4.
| S-EPMC5522382 | biostudies-literature
Project description:Heart failure (HF) is driven by the interplay between regulatory transcription factors and dynamic alterations in chromatin structure. Pathologic gene transactivation in HF is associated with recruitment of histone acetyl-transferases and local chromatin hyperacetylation. We therefore assessed the role of acetyl-lysine reader proteins, or bromodomains, in HF. Using a chemical genetic approach, we establish a central role for BET family bromodomain proteins in gene control during HF pathogenesis. BET inhibition potently suppresses cardiomyocyte hypertrophy in vitro and pathologic cardiac remodeling in vivo. Integrative transcriptional and epigenomic analyses reveal that BET proteins function mechanistically as pause-release factors critical to expression of genes that are central to HF pathogenesis and relevant to the pathobiology of failing human hearts. This study implicates epigenetic readers as essential effectors of transcriptional pause release during HF pathogenesis and identifies BET coactivator proteins as therapeutic targets in the heart.
| S-EPMC4090947 | biostudies-literature
Project description:The Bromo- and Extra-Terminal (BET) proteins BRD2, BRD3, and BRD4 play important roles in transcriptional regulation, epigenetics, and cancer and are the targets of pan-BET selective bromodomain inhibitor JQ1. However, the lack of intra-BET selectivity limits the scope of current inhibitors as probes for target validation and could lead to unwanted side effects or toxicity in a therapeutic setting. We designed Proteolysis Targeted Chimeras (PROTACs) that tether JQ1 to a ligand for the E3 ubiquitin ligase VHL, aimed at triggering the intracellular destruction of BET proteins. Compound MZ1 potently and rapidly induces reversible, long-lasting, and unexpectedly selective removal of BRD4 over BRD2 and BRD3. The activity of MZ1 is dependent on binding to VHL but is achieved at a sufficiently low concentration not to induce stabilization of HIF-1α. Gene expression profiles of selected cancer-related genes responsive to JQ1 reveal distinct and more limited transcriptional responses induced by MZ1, consistent with selective suppression of BRD4. Our discovery opens up new opportunities to elucidate the cellular phenotypes and therapeutic implications associated with selective targeting of BRD4.
| S-EPMC4548256 | biostudies-literature
Project description:In this study, we identified a BET bromodomain (BRD) protein, Brd4, not only as a novel epigenetic regulator of autosomal dominant polycystic kidney disease (ADPKD) but also as a novel client protein of Hsp90. We found that Brd4 was upregulated in Pkd1 mutant mouse renal epithelial cells and tissues. This upregulation of Brd4 appears to result from the chaperone activity of Hsp90 and escape proteasomal degradation. We further identify that Brd4 is an upstream regulator of the expression of c-Myc which has been upregulated in all rodent models of PKD and ADPKD patients with unknown mechanism. Inhibition of Brd4 in Pkd1 mutant renal epithelial cells with JQ1, a selective small-molecular inhibitor of BET BRD protein(s), (1) decreased the levels of c-Myc mRNA and protein; (2) increased the levels of p21 mRNA and protein, which was transcriptionally repressed by c-Myc; (3) decreased the phosphorylation of Rb; and (4) decreased cystic epithelial cell proliferation as shown by inhibition of S-phase entry. Most importantly, treatment with JQ1 strikingly delayed cyst growth and kidney enlargement, and preserved renal function in two early stage genetic mouse strains with Pkd1 mutations. This study not only provides one of the mechanisms of how c-Myc is upregulated in PKD but also suggests that targeting Brd4 with JQ1 may function as a novel epigenetic approach in ADPKD. The unraveled link between Brd4 and Hsp90 in ADPKD may also be a general mechanism for the upregulation of Brd4 in cancer cells and opens up avenues for combination therapies against ADPKD and cancer.
| S-EPMC4476445 | biostudies-literature
Project description:Prostate cancer (PCa) that becomes resistant to hormone castration and next-generation androgen receptor (AR)-targeted therapies, called castration-resistant prostate cancer (CRPC), poses a significant clinical challenge. A better understanding of PCa progression and key molecular mechanisms could bring novel therapies to light. One potential therapeutic target is ERG, a transcription factor aberrantly up-regulated in PCa due to chromosomal rearrangements between androgen-regulated gene TMPRSS2 and ERG. Here we show that the most common PCa-associated truncated ERG T1-E4 (ERGΔ39), encoded by fusion between TMPRSS2 exon 1 and ERG exon 4, binds to bromodomain-1 (BD1) of bromodomain containing protein 4 (BRD4), a member of the bromodomain and extraterminal domain (BET) family. This interaction is partially abrogated by BET inhibitors JQ1 and iBET762. Meta-analysis of published ERG (T1-E4) and BRD4 chromatin immunoprecipitation-sequencing (ChIP-seq) data demonstrates overlap in a substantial portion of their binding sites. Gene expression profile analysis shows some ERG-BRD4 co-target genes are upregulated in CRPC compared to hormone-naïve counterparts. We provide further evidence that ERG-mediated invasion of PCa cells was significantly enhanced by an acetylation-mimicking mutation in ERG that augments the ERG-BRD4 interaction. Our findings reveal that PCa-associated ERG can interact and co-occupy with BRD4 in the genome, and suggest this druggable interaction is critical for ERG-mediated cell invasion and PCa progression.
| S-EPMC5122392 | biostudies-literature