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Super-Enhancer-mediated Control of Liver Fibrosis by BET Bromodomain Proteins

ABSTRACT: Here, we investigate the role of enhancers in myofibroblasts, a cell type that dominates the pathogenesis and progression of tissue fibrosis. We reveal that bromodomain and extra-terminal family members (BETs), an important group of epigenetic readers, are critical for super-enhancer-mediated pro-fibrotic gene expression in hepatic stellate cells (HSCs, lipid-containing liver-specific pericytes), upon activation during liver fibrogenesis give rise to myofibroblasts2-4. We observe significantly enriched localization of BETs to hundreds of super-enhancers associated with genes involved in multiple pro-fibrotic pathways. This unique loading pattern consequentially serves as a molecular mechanism by which BETs modulate pro-fibrotic gene expression in myofibroblasts. Strikingly, suppression of BET-enhancer interaction using small-molecule inhibitors such as JQ1 dramatically blocks activation of HSCs into myofibroblasts and significantly compromises the proliferation of activated HSCs.

ORGANISM(S): Homo sapiens

PROVIDER: GSE58680 | GEO | 2015/12/11

SECONDARY ACCESSION(S): PRJNA253142

REPOSITORIES: GEO

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Super-Enhancer-mediated Control of Liver Fibrosis by BET Bromodomain Proteins

Project description:Here, we investigate the role of enhancers in myofibroblasts, a cell type that dominates the pathogenesis and progression of tissue fibrosis. We reveal that bromodomain and extra-terminal family members (BETs), an important group of epigenetic readers, are critical for super-enhancer-mediated pro-fibrotic gene expression in hepatic stellate cells (HSCs, lipid-containing liver-specific pericytes), upon activation during liver fibrogenesis give rise to myofibroblasts2-4. We observe significantly enriched localization of BETs to hundreds of super-enhancers associated with genes involved in multiple pro-fibrotic pathways. This unique loading pattern consequentially serves as a molecular mechanism by which BETs modulate pro-fibrotic gene expression in myofibroblasts. Strikingly, suppression of BET-enhancer interaction using small-molecule inhibitors such as JQ1 dramatically blocks activation of HSCs into myofibroblasts and significantly compromises the proliferation of activated HSCs. Identification of BRD2, BRD3, BRD4, PolII, PolIIs2p and PolIIs5p binding sites in human stellate LX2 cells that were treated with DMSO (0.1%) or JQ1 (500nM) for 16 hrs.

2015-12-11 | E-GEOD-58680 | biostudies-arrayexpress

Genome wide mapping of long noncoding (lnc) RNAs in hepatic stellate cells

Project description:Hepatic stellate cells are the primary cell type responsible for development of fibrosis in chronic liver disease. We used directional RNA sequencing (RNA-seq) and chromatin immunoprecipitation and sequencing (ChIP-seq) to identify the lncRNAs expressed in human HSCs. We also identified the lncRNAs that change in expression with differentiation of nonfibrotic quiescent HSCs into fibrotic HSC myofibroblasts and those that are regulated by TGF-beta signaling. ChIP-seq was also performed to identify DNA regions occupied by H3K27ac to define super-enhancers in HSC myofibroblasts. This study identified lncRNAs expressed HSCs that may regulate fibrosis. Analysis of genome-wide lncRNA expression using RNA-seq and ChiP-seq in human HSCs under four different conditions

2016-03-23 | E-GEOD-68108 | biostudies-arrayexpress

Genome wide mapping of long noncoding (lnc) RNAs in hepatic stellate cells

2016-03-23 | GSE68108 | GEO

The Forkhead Box F1 Transcription Factor Inhibits Collagen Deposition and Accumulation of Myofibroblasts During Liver Fibrosis

Project description:Hepatic fibrosis is the common end stage to a variety of chronic liver injuries and is characterized by an excessive deposition of extracellular matrix (ECM), which disrupts the liver architecture and impairs liver function. The fibrous lesions are produced by myofibroblasts, which differentiate from hepatic stellate cells (HSC). The myofibroblasts transcriptional networks remain poorly characterized. Previous studies have shown that the Forkhead box F1 (FOXF1) transcription factor is expressed in HSCs and stimulates their activation during acute liver injury; however, the role of FOXF1 in the progression of hepatic fibrosis is unknown. In the present study, we generated αSMACreER;Foxf1fl/fl mice to conditionally inactivate Foxf1 in myofibroblasts during carbon tetrachloride-mediated liver fibrosis. Foxf1 deletion increased collagen depositions and disrupted liver architecture. Timp2 expression was significantly increased in Foxf1-deficient mice while MMP9 activity was reduced. RNA sequencing of purified liver myofibroblasts demonstrated that FOXF1 inhibits expression of pro-fibrotic genes, Col1α2, Col5α2, and Mmp2 in fibrotic livers and binds to active repressors located in promotors and introns of these genes. Overexpression of FOXF1 inhibits Col1a2, Col5a2, and MMP2 in primary murine HSCs in vitro. Altogether, FOXF1 prevents aberrant ECM depositions during hepatic fibrosis by repressing pro-fibrotic gene transcription in myofibroblasts and HSCs.

2019-02-05 | GSE123726 | GEO

Downregulation of the Wnt antagonist Dkk2 links loss of Sept4 and myofibroblastic transformation of hepatic stellate cells

Project description:Background/Aims: Sept4, a subunit of the septin cytoskeleton specifically expressed in quiescent hepatic stellate cells (HSCs), is downregulated through transdifferentiation to fibrogenic and contractile myofibroblastic cells. Since Sept4?/? mice are prone to liver fibrosis, we examined the unknown molecular network underlying liver fibrosis by probing the association between loss of Sept4 and accelerated transdifferentiation of HSCs. Methods: We compared the transcriptomes of Sept4+/+ and Sept4?/? HSCs by differential DNA microarray analysis and quantitative RT-PCR. Based on reduced dickkopf2 (Dkk2) gene expression in Sept4?/? HSCs, we tested whether supplementing Dkk2 could suppress myofibroblastic transformation of Sept4?/? HSCs. We used a lymphoid enhancer-binding factor/transcription factor-luciferase reporter assay to test whether Dkk2 can exert anti-fibrotic effects by interfering with the canonical Wnt pathway. Results: We observed consistent upregulation of Dkk2 in primary cultured HSCs and in a carbon tetrachloride hepatitis model in mice, which decreased with loss of Sept4. Supplementing Dkk2 suppressed the induction of pro-fibrotic genes (?-smooth muscle actin and 2 collagen genes) and induced an anti-fibrotic gene (Smad7) in Sept4?/? HSCs. In human liver specimens with inflammation and fibrosis, Dkk2 immunoreactivity appeared to be positively correlated with the degree of fibrotic changes. Conclusions: Pro-fibrotic transformation of HSCs through the loss of Sept4 is partly due to reduced expression of Dkk2 and its homologues, and the resulting disinhibition of the canonical Wnt pathway. We induced Liver Cirrhosis to SEPT4-KO or wild type mouse by CCl4, and examined mRNA expression profiling in hepatic stellate cell of these mouse.

2012-06-02 | E-GEOD-24588 | biostudies-arrayexpress

Models of Human Core Transcriptional Regulatory Circuitries

Project description:A small set of core transcription factors (TFs) dominates control of the gene expression program in embryonic stem cells and other well-studied cellular models. These core TFs collectively regulate their own gene expression, thus forming an interconnected autoregulatory loop that can be considered the core transcriptional regulatory circuitry (CRC) for that cell type. There is limited knowledge of core TFs, and thus models of core regulatory circuitry, for most cell types. We recently discovered that genes encoding known core TFs forming CRCs are driven by super-enhancers, which provides an opportunity to systematically predict CRCs in poorly studied cell types through super-enhancer mapping. Here we use super-enhancer maps to generate CRC models for 75 human cell and tissue types. These core circuitry models should prove valuable for further investigating cell type-specific transcriptional regulation in healthy and diseased cells. ChIP-Seq for RUNX1 and GATA3 in Jurkat T cell acute lymphoblastic leukemia cells.

2015-12-18 | E-GEOD-76181 | biostudies-arrayexpress

Master Transcription Factors and Mediator Establish Super-Enhancers at Key Cell Identity Genes

Project description:The master transcription factors Oct4, Sox2 and Nanog bind enhancer elements and recruit the Mediator co-activator to activate much of the gene expression program of embryonic stem cells (ESCs). We report here that these ESC master transcription factors and Mediator form M-bM-^@M-^\super-enhancersM-bM-^@M-^] at most genes that are known to control the pluripotent state, including those encoding the master transcription factors themselves. These super-enhancers consist of extraordinarily large genomic domains occupied by exceptional amounts of Oct4 and Mediator. Super-enhancers stimulate considerably higher transcription than typical enhancers in reporter vectors. ESC differentiation causes preferential loss of expression of super-enhancer -associated genes. Super-enhancers are also found at key cell identity genes in differentiated cells. These results implicate super-enhancers in the control of mammalian cell identity and differentiation and suggest that these elements might generally be used to identify genes that control cell-type specific gene expression programs in many mammalian cells. ChIP-Seq and RNA-seq of Med1 in ZHBTc4 ES during treatment with doxycycline. ChIP-Seq data of Med1 in 38B9 pro-B cells.

2013-01-02 | E-GEOD-42474 | biostudies-arrayexpress

Defining super-enhancer landscape in triple-negative breast cancer by multiomic profiling

Project description:Here we apply integrated epigenomic and transcriptomic profiling to uncover super-enhancer heterogeneity between breast cancer subtypes, and provide clinically relevant biological insights towards TNBC. Using CRISPR/Cas9-mediated gene editing, we identify genes that are specifically regulated by TNBC-specific super-enhancers, including FOXC1 and MET, thereby unveiling a mechanism for specific overexpression of the key oncogenes in TNBC. We also identify ANLN as a novel TNBC-specific gene regulated by super-enhancer. Our studies reveal a TNBC-specific epigenomic landscape, contributing to the dysregulated oncogene expression in breast tumorigenesis.

2021-03-04 | PXD024505 | iProX

Master Transcription Factors and Mediator Establish Super-Enhancers at Key Cell Identity Genes [ChIP-Seq]

Project description:The master transcription factors Oct4, Sox2 and Nanog bind enhancer elements and recruit the Mediator co-activator to activate much of the gene expression program of embryonic stem cells (ESCs). We report here that the ESC master transcription factors and Mediator form “super-enhancers” at most genes known to control the pluripotent state, including those encoding the master transcription factors themselves. These super-enhancers consist of extraordinarily large genomic domains occupied by exceptional amounts of Oct4, Sox2, Nanog, Klf4, Esrrb and Mediator. Super-enhancers stimulate considerably higher transcription than typical enhancers in vivo and in reporter vectors. Reduced levels of Oct4 or Mediator cause preferential loss of expression of super-enhancer-associated genes relative to other genes, suggesting how changes in gene expression programs might be accomplished during development. In other more differentiated cells, super-enhancers containing cell-type-specific master transcription factors are also found at genes that define cell identity. These results implicate super-enhancers in the control of mammalian cell identity and differentiation. ChIP-Seq and controls associated with Super-Enhancers in murine cell types

2013-02-13 | E-GEOD-44286 | biostudies-arrayexpress

Downregulation of the Wnt antagonist Dkk2 links loss of Sept4 and myofibroblastic transformation of hepatic stellate cells

Project description:Background/Aims: Sept4, a subunit of the septin cytoskeleton specifically expressed in quiescent hepatic stellate cells (HSCs), is downregulated through transdifferentiation to fibrogenic and contractile myofibroblastic cells. Since Sept4−/− mice are prone to liver fibrosis, we examined the unknown molecular network underlying liver fibrosis by probing the association between loss of Sept4 and accelerated transdifferentiation of HSCs. Methods: We compared the transcriptomes of Sept4+/+ and Sept4−/− HSCs by differential DNA microarray analysis and quantitative RT-PCR. Based on reduced dickkopf2 (Dkk2) gene expression in Sept4−/− HSCs, we tested whether supplementing Dkk2 could suppress myofibroblastic transformation of Sept4−/− HSCs. We used a lymphoid enhancer-binding factor/transcription factor-luciferase reporter assay to test whether Dkk2 can exert anti-fibrotic effects by interfering with the canonical Wnt pathway. Results: We observed consistent upregulation of Dkk2 in primary cultured HSCs and in a carbon tetrachloride hepatitis model in mice, which decreased with loss of Sept4. Supplementing Dkk2 suppressed the induction of pro-fibrotic genes (α-smooth muscle actin and 2 collagen genes) and induced an anti-fibrotic gene (Smad7) in Sept4−/− HSCs. In human liver specimens with inflammation and fibrosis, Dkk2 immunoreactivity appeared to be positively correlated with the degree of fibrotic changes. Conclusions: Pro-fibrotic transformation of HSCs through the loss of Sept4 is partly due to reduced expression of Dkk2 and its homologues, and the resulting disinhibition of the canonical Wnt pathway.

2012-06-03 | GSE24588 | GEO

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