CHROMATIN LANDSCAPES REVEAL DEVELOPMENTALLY ENCODED TRANSCRIPTIONAL STATES THAT DEFINE GLIOBLASTOMA [ChIP-Seq]
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE119755 | GEO | 2019/03/18
REPOSITORIES: GEO
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Project description:Glioblastoma is an incurable brain cancer characterized by high genetic and pathological heterogeneity. Here we mapped active chromatin landscapes with gene expression, whole-exomes, copy number profiles, and DNA methylomes across 44 glioblastoma stem cell (GSCs) models, 50 primary glioblastomas, and 10 neural stem cells (NSCs) with the goal of identifying essential super enhancer (SE)-associated genes and the core transcription factors that establish them and glioblastoma identity. Glioblastomas segregate with two dominant enhancer profiles that coopt unique developmental transcription factor regulatory programs to enforce tumor identity. From group specific enhancer profiles, we inferred core transcription factors that define subgroup identity. These transcription factors show higher activity in glioblastomas versus normal neural stem cells, are associated with poor clinical outcomes, and are required for glioblastoma growth in vitro and in vivo. Given challenges with genetically-defined targeted therapies for glioblastoma, we propose targeting underlying transcriptional identity may serve as an important therapeutic strategy.
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Project description:Glioblastomas are highly lethal cancers, containing self-renewing glioblastoma stem cells (GSCs). Here, we show that GSCs, differentiated glioblastoma cells (DGCs), and normal brain cultures all displayed robust circadian rhythms, yet GSCs alone displayed exquisite dependence on core clock transcription factors, BMAL1 and CLOCK, for optimal cell growth. Downregulation of BMAL1 or CLOCK in GSCs induced cell cycle arrest and apoptosis. Chromatin immunoprecipitation revealed BMAL1 preferentially bound at metabolic genes in GSCs, associated with differences in active chromatin regions compared to NSCs. Targeting BMAL1 or CLOCK attenuated mitochondrial metabolic function and reduced expression of the tricarboxylic acid (TCA) cycle enzymes. Small molecule agonists of two independent BMAL1::CLOCK negative regulators, the Cryptochromes and REV-ERBs, downregulated stem cell factors and reduced GSC growth. Combination of Cryptochrome and REV-ERB agonists induced synergistic anti-tumor efficacy. Collectively, GSCs coopt circadian regulators beyond canonical circadian circuitry to promote stemness maintenance and metabolism, offering novel therapeutic paradigms.
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Project description:<p>Non-coding elements in our genomes that play critical roles in complex disease are frequently marked by highly unstable RNA species. Sequencing nascent RNAs attached to an actively transcribing RNA polymerase complex can identify unstable RNAs, including those templated from gene-distal enhancers (eRNAs). However, nascent RNA sequencing techniques remain challenging to apply in some cell lines and especially to intact tissues, limiting broad applications in fields such as cancer genomics and personalized medicine. Here we report the development of chromatin run-on and sequencing (ChRO-seq), a novel run-on technology that maps the location of RNA polymerase using virtually any frozen tissue sample, including samples with degraded RNA that are intractable to conventional RNA-seq. We used ChRO-seq to develop the first maps of nascent transcription in 23 human glioblastoma (GBM) brain tumors and patient derived xenografts. Remarkably, >90,000 distal enhancers discovered using the signature of eRNA biogenesis within primary GBMs closely resemble those found in the normal human brain, and diverge substantially from GBM cell models. Despite extensive overall similarity, 12% of enhancers in each GBM distinguish normal and malignant brain tissue. These enhancers drive regulatory programs similar to the developing nervous system and are enriched for transcription factor binding sites that specify a stem-like cell fate. These results demonstrate that GBMs largely retain the enhancer landscape associated with their tissue of origin, but selectively adopt regulatory programs that are responsible for driving stem-like cell properties. We also identified enhancers and their associated transcription factors that regulate genes characteristic of each known GBM subtype, and discovered a core group of transcription factors that control the expression of genes associated with clinical outcomes. This study uncovers new insights into the molecular etiology of GBM and introduces ChRO-seq which can now be used to map regulatory programs contributing to a variety of complex diseases.</p>
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Project description:Here, we show that the Kdm5c/Smcx member of the Jarid1 family of H3K4 demethylases is recruited to both enhancer and core promoter elements in ES and neuronal progenitor cells (NPC). Knockdown of Kdm5c deregulates transcription via a local increase in H3K4me3. While at core promoters the function of Kdm5c is to restrict transcription, loss of Kdm5c impairs enhancer function. Remarkably, an impaired enhancer function activates promoter activity from Kdm5c-bound intergenic regions. Our results demonstrate that the Kdm5c demethylase plays a crucial role in the functional identity and discrimination of enhancers and core promoters. We speculate that this is related to recruitment of H3K4me3 binders like the TFIID and NURF complexes6-8. Providing functional identity to genomic regions through balancing enzymes that deposit and remove histone modifications may prove to be a general epigenetic mechanism for the functional indexing of eukaryotic genomes. Examination of the KDM5C binding sites in mouse embryonic stem cells and in neuronal progenitor cells. Effect of KDM5C knock down on H3K4me3 and H3K4me1 levels and gene expression.
2013-04-01 | E-GEOD-34975 | biostudies-arrayexpress
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Project description:<p>Transcription factor p63 is a key regulator of epidermal keratinocyte proliferation and differentiation. Mutations in the p63 DNA-binding domain are associated with Ectrodactyly Ectodermal Dysplasia Cleft Lip/Palate (EEC) syndrome. Underlying molecular mechanism of these mutations however remain unclear. Here we characterized the transcriptome and epigenome of p63 mutant keratinocytes derived from EEC patients. The transcriptome of p63 mutant keratinocytes deviated from the normal epidermal cell identity. Epigenomic analyses showed an altered enhancer landscape in p63 mutant keratinocytes contributed by loss of p63-bound active enhancers and by unexpected gain of enhancers. The gained enhancers were frequently bound by deregulated transcription factors such as RUNX1. Reversing RUNX1 overexpression partially rescued deregulated gene expression and the altered enhancer landscape. Our findings identify an unreported disease mechanism whereby mutant p63 rewires the enhancer landscape and affects epidermal cell identity, consolidating the pivotal role of p63 in controlling the enhancer landscape of epidermal keratinocytes.</p>
| phs001737 | dbGaP
Project description:Chavez2009 - a core regulatory network of OCT4 in human embryonic stem cells
A core OCT4-regulated network has been identified as a test case, to analyase stem cell characteristics and cellular differentiation.
This model is described in the article:
In silico identification of a core regulatory network of OCT4 in human embryonic stem cells using an integrated approach.
Chavez L, Bais AS, Vingron M, Lehrach H, Adjaye J, Herwig R
BMC Genomics, 2009, 10:314
Abstract:
BACKGROUND: The transcription factor OCT4 is highly expressed in pluripotent embryonic stem cells which are derived from the inner cell mass of mammalian blastocysts. Pluripotency and self renewal are controlled by a transcription regulatory network governed by the transcription factors OCT4, SOX2 and NANOG. Recent studies on reprogramming somatic cells to induced pluripotent stem cells highlight OCT4 as a key regulator of pluripotency.
RESULTS: We have carried out an integrated analysis of high-throughput data (ChIP-on-chip and RNAi experiments along with promoter sequence analysis of putative target genes) and identified a core OCT4 regulatory network in human embryonic stem cells consisting of 33 target genes. Enrichment analysis with these target genes revealed that this integrative analysis increases the functional information content by factors of 1.3 - 4.7 compared to the individual studies. In order to identify potential regulatory co-factors of OCT4, we performed a de novo motif analysis. In addition to known validated OCT4 motifs we obtained binding sites similar to motifs recognized by further regulators of pluripotency and development; e.g. the heterodimer of the transcription factors C-MYC and MAX, a prerequisite for C-MYC transcriptional activity that leads to cell growth and proliferation.
CONCLUSION: Our analysis shows how heterogeneous functional information can be integrated in order to reconstruct gene regulatory networks. As a test case we identified a core OCT4-regulated network that is important for the analysis of stem cell characteristics and cellular differentiation. Functional information is largely enriched using different experimental results. The de novo motif discovery identified well-known regulators closely connected to the OCT4 network as well as potential new regulators of pluripotency and differentiation. These results provide the basis for further targeted functional studies.
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2005-01-01 | MODEL1305010000 | BioModels
Project description:Recent studies demonstrated that tumor cells with stem cell-like properties can be cultured from human glioblastomas by using conditions that select for the expansion of neural stem cells. We established glioblastoma stem-like (GS-) cell cultures from 9 different glioblastomas, 8 of which generated stably expandable cell lines. Analyzing GS-cell cultures, we discovered two clearly discernable phenotypes. Microarray analysis showed that the 4 GSf cell lines shared expression profiles dominated by genes involved in nervous system development and neuropeptide signaling, while the 5 GSr lines shared expression signatures enriched for extracellular matrix-proteins. Keywords: Cell line comparison
2007-12-04 | GSE8049 | GEO