Tumor Microenvironment-induced BRD4 Activation Results in Chromatin Remodeling and Therapy Resistance in Colorectal Cancer [ChIP-seq]
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE160352 | GEO | 2021/06/07
REPOSITORIES: GEO
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Project description:BRD4 is a key regulatory factor in multiple cancers and cellular stress responses with pleotropic functions. BRD4 regulates chromatin remodeling and transcription through its histone acetyltransferase (HAT) and kinase activities, respectively. The mechanism responsible for switching BRD4 from a chromatin to transcriptional regulator is currently unknown. Here, we report that in response to a broad range of stimuli, this switch is mediated by the JNK kinase which directly interacts with BRD4. JNK specifically phosphorylates human BRD4 at Ser1117, Thr1186 and Thr1212, triggering transient BRD4 release from chromatin. JNK phosphorylation of BRD4 halts its HAT-mediated chromatin regulation and activates its transcription-enhancing kinase function. BRD4 release from chromatin is necessary to toggle between its enzymatic activities: chromatin-bound BRD4 is kinase inactive and RNA Pol II-bound BRD4 does not acetylate chromatin. BRD4 release from chromatin augments its interaction with and phosphorylation of key transcriptional regulators RNA Pol II, PTEFb and c-MYC. The PP4 phosphatase dephosphorylates JNK phosphorylated BRD4 in the nucleoplasm, which promotes its interaction with RNA Pol II at transcriptionally active sites. Accordingly, JNK-mediated release of BRD4 from chromatin leads to significantly elevated transcription of BRD4-regulated immune and inflammatory response genes through enhanced BRD4-Pol II interaction at the promoters of these genes. JNK phosphorylation of BRD4 occurs during T-cell activation and is required for epithelial to mesenchymal transition (EMT) in prostate cancer cells. These findings thus characterize a novel mechanism that triggers the transition of BRD4 from a chromatin regulator to transcriptional activator during stress/immune/inflammatory responses and EMT.
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Project description:BRD4 functions as an epigenetic reader and plays a crucial role in regulating transcription and genome stability. Dysregulation of BRD4 is frequently observed in various human cancers. However, the molecular details of BRD4 regulation remain largely unknown. Here, we report that PRMT2- and PRMT4-mediated arginine methylation is pivotal for BRD4-dependent transcription, DNA repair, and tumor growth. Specifically, PRMT2/4 interact with and methylates BRD4 at R179, R181, and R183. This arginine methylation selectively controls a transcriptional program by promoting BRD4 enrichment at the hyper-acetylated chromatin regions. Moreover, BRD4 arginine methylation is induced by DNA damage and thereby promotes its binding to chromatin for DNA repair. Deficiency in BRD4 arginine methylation significantly suppresses tumor growth and sensitizes cells to BET inhibitors and DNA damaging agents. Therefore, our findings reveal an arginine methylation-dependent regulatory mechanism of BRD4 function and highlight targeting PRMT2/4 for better anti-tumor effect of BET inhibitors and DNA damaging agents.
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Project description:BRD4 governs pathological cardiac gene expression by binding acetylated chromatin, resulting in enhanced RNA polymerase II (Pol II) phosphorylation and transcription elongation. Here, we describe a signal-dependent mechanism for regulation of BRD4 in cardiomyocytes. BRD4 expression is suppressed by microRNA-9 (miR-9), which targets the 3’ untranslated region of the Brd4 transcript. In response to stress stimuli, miR-9 is downregulated, leading to derepression of BRD4 and enrichment of BRD4 at long-range super-enhancers (SEs) associated with pathological cardiac genes. A miR-9 mimic represses stimulus-dependent targeting of BRD4 to SEs and blunts Pol II phosphorylation at proximal transcription start sites, without affecting BRD4 binding to SEs that control constitutively expressed cardiac genes. These findings suggest that dynamic enrichment of BRD4 at SEs genome-wide serves a crucial role in the control of stress-induced cardiac gene expression, and define a miR-dependent signaling mechanism for the regulation of chromatin state and Pol II phosphorylation.
2016-10-06 | GSE83228 | GEO
Project description:BRD4 governs pathological cardiac gene expression by binding acetylated chromatin, resulting in enhanced RNA polymerase II (Pol II) phosphorylation and transcription elongation. Here, we describe a signal-dependent mechanism for regulation of BRD4 in cardiomyocytes. BRD4 expression is suppressed by microRNA-9 (miR-9), which targets the 3’ untranslated region of the Brd4 transcript. In response to stress stimuli, miR-9 is downregulated, leading to derepression of BRD4 and enrichment of BRD4 at long-range super-enhancers (SEs) associated with pathological cardiac genes. A miR-9 mimic represses stimulus-dependent targeting of BRD4 to SEs and blunts Pol II phosphorylation at proximal transcription start sites, without affecting BRD4 binding to SEs that control constitutively expressed cardiac genes. These findings suggest that dynamic enrichment of BRD4 at SEs genome-wide serves a crucial role in the control of stress-induced cardiac gene expression, and define a miR-dependent signaling mechanism for the regulation of chromatin state and Pol II phosphorylation.
2016-10-06 | GSE82243 | GEO
Project description:Transcriptional elongation by RNA polymerase II (Pol II) is regulated by positive transcription elongation factor b (P-TEFb) in association with Bromodomain-containing protein 4 (BRD4). We used genome-wide chromatin immunoprecipitation sequencing in primary human CD4+ T cells to reveal that BRD4 co-localizes with Ser2-phosphorylated Pol II (Pol II Ser2) at both enhancers and promoters of active genes. Disruption of bromodomain:histone acetylation interactions by JQ1, a small-molecule bromodomain inhibitor, resulted in decreased BRD4 binding, reduced Pol II Ser2, and reduced expression of lineage-specific genes in primary human CD4+ T cells. A large number of JQ1-disrupted BRD4 binding regions exhibited di-acetylated H4 (lysine-5 and -8) and H3K27 acetylation (H3K27ac), which correlated with the presence of histone acetyltransferases and deacetylases. Genes associated with BRD4/H3K27ac co-occupancy exhibited significantly higher activity than those associated with H3K27ac or BRD4 binding alone. Comparison of BRD4 binding in T cells and in human embryonic stem cells revealed that enhancer BRD4 binding sites were predominantly lineage-specific. Our findings suggest that BRD4-driven Pol II phosphorylation at serine 2 plays an important role in regulating lineage-specific gene transcription in human CD4+ T cells. Examination of BRD4, total Pol II, serine 2 phosphorylated Pol II and serine 5 phosphorylated Pol II binding in CD4+ T cells (with and without JQ1 treatment) and BRD4 binding in human embryonic stems cell; PolyA RNA expression in CD4+ T cells( with and without JQ1 treatment) using RNA-seq
2012-11-14 | E-GEOD-33281 | biostudies-arrayexpress
Project description:BRD4 is a key regulatory factor in multiple cancers and cellular stress responses with pleotropic functions. It regulates chromatin remodeling and transcription through its histone acetyltransferase (HAT) and kinase activities, respectively. The mechanism responsible for switching BRD4 from a chromatin to transcriptional regulator is currently unknown. Here, we report that in response to a broad range of stimuli, this switch is mediated by the JNK kinase which directly interacts with BRD4. JNK specifically phosphorylates human BRD4 at Ser1117, Thr1186 and Thr1212, triggering transient BRD4 release from chromatin. JNK phosphorylation of BRD4 halts its HAT-mediated chromatin regulation and activates its transcription-enhancing kinase function. BRD4 release from chromatin is necessary to toggle between its enzymatic activities: chromatin-bound BRD4 is kinase inactive and RNA Pol II-bound BRD4 does not acetylate chromatin. BRD4 release from chromatin augments its interaction with and phosphorylation of key transcriptional regulators RNA Pol II, PTEFb and c-MYC. The PP4 phosphatase dephosphorylates JNK phosphorylated BRD4 in the nucleoplasm, which promotes its interaction with RNA Pol II at transcriptionally active sites. Accordingly, JNK-mediated release of BRD4 from chromatin leads to significantly elevated transcription of BRD4-regulated immune and inflammatory response genes through enhanced BRD4-Pol II interaction at the promoters of these genes. JNK phosphorylation of BRD4 occurs during T-cell activation and is required for epithelial to mesenchymal transition (EMT) in prostate cancer cells. These findings thus characterize a novel mechanism that triggers the transition of BRD4 from a chromatin regulator to transcriptional activator during stress/immune/inflammatory responses and EMT.
2024-09-16 | GSE252981 | GEO
Project description:BRD4 is a key regulatory factor in multiple cancers and cellular stress responses with pleotropic functions. It regulates chromatin remodeling and transcription through its histone acetyltransferase (HAT) and kinase activities, respectively. The mechanism responsible for switching BRD4 from a chromatin to transcriptional regulator is currently unknown. Here, we report that in response to a broad range of stimuli, this switch is mediated by the JNK kinase which directly interacts with BRD4. JNK specifically phosphorylates human BRD4 at Ser1117, Thr1186 and Thr1212, triggering transient BRD4 release from chromatin. JNK phosphorylation of BRD4 halts its HAT-mediated chromatin regulation and activates its transcription-enhancing kinase function. BRD4 release from chromatin is necessary to toggle between its enzymatic activities: chromatin-bound BRD4 is kinase inactive and RNA Pol II-bound BRD4 does not acetylate chromatin. BRD4 release from chromatin augments its interaction with and phosphorylation of key transcriptional regulators RNA Pol II, PTEFb and c-MYC. The PP4 phosphatase dephosphorylates JNK phosphorylated BRD4 in the nucleoplasm, which promotes its interaction with RNA Pol II at transcriptionally active sites. Accordingly, JNK-mediated release of BRD4 from chromatin leads to significantly elevated transcription of BRD4-regulated immune and inflammatory response genes through enhanced BRD4-Pol II interaction at the promoters of these genes. JNK phosphorylation of BRD4 occurs during T-cell activation and is required for epithelial to mesenchymal transition (EMT) in prostate cancer cells. These findings thus characterize a novel mechanism that triggers the transition of BRD4 from a chromatin regulator to transcriptional activator during stress/immune/inflammatory responses and EMT.
2024-09-16 | GSE252980 | GEO
Project description:BRD4 is a key regulatory factor in multiple cancers and cellular stress responses with pleotropic functions. It regulates chromatin remodeling and transcription through its histone acetyltransferase (HAT) and kinase activities, respectively. The mechanism responsible for switching BRD4 from a chromatin to transcriptional regulator is currently unknown. Here, we report that in response to a broad range of stimuli, this switch is mediated by the JNK kinase which directly interacts with BRD4. JNK specifically phosphorylates human BRD4 at Thr1186 and Thr1212, triggering transient BRD4 release from chromatin. JNK phosphorylation of BRD4 halts its HAT-mediated chromatin regulation and activates its transcription-enhancing kinase function. BRD4 release from chromatin is necessary to toggle between its enzymatic activities: chromatin-bound BRD4 is kinase inactive and RNA Pol II-bound BRD4 does not acetylate chromatin. BRD4 release from chromatin augments its interaction with and phosphorylation of key transcriptional regulators RNA Pol II, PTEFb and c-MYC. The PP4 phosphatase dephosphorylates JNK phosphorylated BRD4 in the nucleoplasm, which promotes its interaction with RNA Pol II at transcriptionally active sites. Accordingly, JNK-mediated release of BRD4 from chromatin leads to significantly elevated transcription of BRD4-regulated immune and inflammatory response genes through enhanced BRD4-Pol II interaction at the promoters of these genes. JNK phosphorylation of BRD4 occurs during T-cell activation and is required for epithelial to mesenchymal transition (EMT) in prostate cancer cells. These findings thus characterize a novel mechanism that triggers the transition of BRD4 from a chromatin regulator to transcriptional activator during stress/immune/inflammatory responses and EMT.
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Project description:Chromatin regulators have become highly attractive targets for cancer therapy, yet many of these regulators are expressed in a broad range of healthy cells and contribute generally to gene expression. An important conundrum has thus emerged: how can inhibition of a general regulator of gene expression produce selective effects at specific oncogenes? Here we investigate how inhibition of the transcriptional coactivator BRD4 (Bromodomain containing 4) leads to selective inhibition of disease-critical oncogenes in a highly malignant blood cancer, multiple myeloma (MM). We found that BRD4 generally occupies the promoter elements of active genes together with the Mediator coactivator, but remarkably high levels of these two coactivator proteins were associated with a small set of exceptionally large enhancers. These super-enhancers are associated with genes that feature prominently in MM biology, including the MYC oncogene. Treatment of MM tumor cells with the BET-bromodomain inhibitor JQ1 led to preferential loss of BRD4 at super-enhancers and consequent transcription elongation defects that preferentially impact genes with super-enhancers, including the c-MYC oncogene. Super-enhancers were found at key oncogenic drivers in many other tumor cells. Thus, super-enhancers can regulate oncogenic drivers in tumor cells, which in some cells can be preferentially disrupted by BRD4 inhibition, which in turn contributes to the selective transcriptional effects observed at these oncogenes. These observations have implications for the discovery of novel cancer therapeutics directed at components of super-enhancers in diverse tumor types. ChIP-Seq for chromatin regulators and RNA Polymerase II in multiple myeloma, glioblastoma multiforme, and small cell lung cancer
2013-01-02 | E-GEOD-42355 | biostudies-arrayexpress
Project description:Tumor Microenvironment-induced BRD4 Activation Results in Chromatin Remodeling and Therapy Resistance in Colorectal Cancer
| PRJNA671678 | ENA