Similar Datasets
Project description:Various types of repetitive sequences are dysregulated in cancer but their contributions to oncogenesis are yet to be determined. Here we combine nascent transcription profiling with epigenome editing to test the function of GGAA microsatellites in Ewing sarcoma, a pediatric bone cancer where the oncogenic fusion protein EWS-FLI1 induces chromatin features of active enhancers at this class of repeats. Silencing of chromatin through epigenome editing at specific GGAA repeats abolished local nascent transcription, decreased the expression of neighboring target genes and, in the case of a repeat associated with the SOX2 locus, reduced the growth of tumor xenografts. Our studies directly demonstrate that repeat elements can acquire enhancer functions in cancer and become critical components of oncogenic gene regulation programs.
2018-07-30 | GSE106915 | GEO
Project description:Various types of repetitive sequences are dysregulated in cancer but their contributions to oncogenesis are yet to be determined. Here we combine nascent transcription profiling with epigenome editing to test the function of GGAA microsatellites in Ewing sarcoma, a pediatric bone cancer where the oncogenic fusion protein EWS-FLI1 induces chromatin features of active enhancers at this class of repeats. Silencing of chromatin through epigenome editing at specific GGAA repeats abolished local nascent transcription, decreased the expression of neighboring target genes and, in the case of a repeat associated with the SOX2 locus, reduced the growth of tumor xenografts. Our studies directly demonstrate that repeat elements can acquire enhancer functions in cancer and become critical components of oncogenic gene regulation programs. Raw data for MSC Samples GSM2857574-GSM2857587 are subject to privacy restrictions and were not submitted.
2018-07-30 | GSE106914 | GEO
Project description:Various types of repetitive sequences are dysregulated in cancer. In Ewing sarcoma, the oncogenic fusion protein EWS-FLI1 induces chromatin features typical of active enhancers at GGAA microsatellite repeats, but the function of these sites has not been directly demonstrated. Here, by combining nascent transcription profiling with epigenome editing, we found that a subset of GGAA microsatellite repeats is transcriptionally active in Ewing sarcoma and that silencing individual repeats abolishes local nascent transcription and leads to markedly reduced expression of putative target genes. Epigenome silencing of these repeat sites does not affect gene expression in unrelated cells, can prevent the induction of gene expression by EWS-FLI1, and, in the case of a GGAA repeat that controls SOX2 expression from a distance of 470 kb, is sufficient to impair the growth of Ewing sarcoma xenografts. Using an experimental approach that is broadly applicable to testing different types of repetitive genomic elements, our study directly demonstrates that specific repeat microsatellites can have critical gene regulation functions in cancer and thus represent tumor-specific vulnerabilities that may be exploited to develop new therapies.
| S-EPMC6075149 | biostudies-literature
Project description:Epigenome editing of microsatellite repeat enhancers reveals specific regulatory functions and tumor dependencies
| PRJNA418451 | ENA
Project description:Epigenome editing of microsatellite repeat enhancers reveals specific regulatory functions and tumor dependencies [NRO-Seq]
| PRJNA418458 | ENA
Project description:Epigenome editing of microsatellite repeat enhancers reveals specific regulatory functions and tumor dependencies [ChIP-Seq]
| PRJNA418456 | ENA
Project description:Epigenome editing with the CRISPR (clustered, regularly interspaced, short palindromic repeats)-Cas9 platform is a promising technology for modulating gene expression to direct cell phenotype and to dissect the causal epigenetic mechanisms of gene regulation. Fusions of nuclease-inactive dCas9 to the Krüppel-associated box (KRAB) repressor (dCas9-KRAB) can silence target gene expression, but the genome-wide specificity and the extent of heterochromatin formation catalyzed by dCas9-KRAB are not known. We targeted dCas9-KRAB to the HS2 enhancer, a distal regulatory element that orchestrates the expression of multiple globin genes, and observed highly specific induction of H3K9 trimethylation (H3K9me3) at the enhancer and decreased chromatin accessibility of both the enhancer and its promoter targets. Targeted epigenetic modification of HS2 silenced the expression of multiple globin genes, with minimal off-target changes in global gene expression. These results demonstrate that repression mediated by dCas9-KRAB is sufficiently specific to disrupt the activity of individual enhancers via local modification of the epigenome.
| S-EPMC4666778 | biostudies-literature
Project description:For ∼30 million years, the eggs of Hawaiian Drosophila were laid in ever-changing environments caused by high rates of island formation. The associated diversification of the size and developmental rate of the syncytial fly embryo would have altered morphogenic gradients, thus necessitating frequent evolutionary compensation of transcriptional responses. We investigate the consequences these radiations had on transcriptional enhancers patterning the embryo to see whether their pattern of molecular evolution is different from non-Hawaiian species. We identify and functionally assay in transgenic D. melanogaster the Neurogenic Ectoderm Enhancers from two different Hawaiian Drosophila groups: (i) the picture wing group, and (ii) the modified mouthparts group. We find that the binding sites in this set of well-characterized enhancers are footprinted by diverse microsatellite repeat (MSR) sequences. We further show that Hawaiian embryonic enhancers in general are enriched in MSR relative to both Hawaiian non-embryonic enhancers and non-Hawaiian embryonic enhancers. We propose embryonic enhancers are sensitive to Activator spacing because they often serve as assembly scaffolds for the aggregation of transcription factor activator complexes. Furthermore, as most indels are produced by microsatellite repeat slippage, enhancers from Hawaiian Drosophila lineages, which experience dynamic evolutionary pressures, would become grossly enriched in MSR content.
| S-EPMC4076327 | biostudies-literature
Project description:Technologies that enable targeted manipulation of epigenetic marks could be used to precisely control cell phenotype or interrogate the relationship between the epigenome and transcriptional control. Here we describe a programmable, CRISPR-Cas9-based acetyltransferase consisting of the nuclease-null dCas9 protein fused to the catalytic core of the human acetyltransferase p300. The fusion protein catalyzes acetylation of histone H3 lysine 27 at its target sites, leading to robust transcriptional activation of target genes from promoters and both proximal and distal enhancers. Gene activation by the targeted acetyltransferase was highly specific across the genome. In contrast to previous dCas9-based activators, the acetyltransferase activates genes from enhancer regions and with an individual guide RNA. We also show that the core p300 domain can be fused to other programmable DNA-binding proteins. These results support targeted acetylation as a causal mechanism of transactivation and provide a robust tool for manipulating gene regulation.
| S-EPMC4430400 | biostudies-literature
Project description:Mammalian gene regulation is dependent on tissue-specific enhancers that can act across large distances to influence transcriptional activity. Mapping experiments have identified hundreds of thousands of putative enhancers whose functionality is supported by cell type-specific chromatin signatures and striking enrichments for disease-associated sequence variants. However, these studies did not address the in vivo functions of the putative elements or their chromatin states and did not determine which genes, if any, a given enhancer regulates. Here we present a strategy to investigate endogenous regulatory elements by selectively altering their chromatin state using programmable reagents. Transcription activator-like (TAL) effector repeat domains fused to the LSD1 histone demethylase efficiently remove enhancer-associated chromatin modifications from target loci, without affecting control regions. We find that inactivation of enhancer chromatin by these fusion proteins frequently causes downregulation of proximal genes, revealing enhancer target genes. Our study demonstrates the potential of epigenome editing tools to characterize an important class of functional genomic elements.
| S-EPMC3858395 | biostudies-literature