RNA:DNA hybrids in the human genome have distinctive nucleotide characteristics, chromatin composition, and transcriptional relationships
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE68953 | GEO | 2015/06/15
SECONDARY ACCESSION(S): PRJNA284154
REPOSITORIES: GEO
Similar Datasets
Project description:RNA:DNA hybrids represent a non-canonical nucleic acid structure that has been associated with a range of human diseases and potential transcriptional regulatory functions. Mapping of RNA:DNA hybrids in human cells reveals them to have a number of characteristics that give insights into their functions.We find RNA:DNA hybrids to occupy millions of base pairs in the human genome. A directional sequencing approach shows the RNA component of the RNA:DNA hybrid to be purine-rich, indicating a thermodynamic contribution to their in vivo stability. The RNA:DNA hybrids are enriched at loci with decreased DNA methylation and increased DNase hypersensitivity, and within larger domains with characteristics of heterochromatin formation, indicating potential transcriptional regulatory properties. Mass spectrometry studies of chromatin at RNA:DNA hybrids shows the presence of the ILF2 and ILF3 transcription factors, supporting a model of certain transcription factors binding preferentially to the RNA:DNA conformation.Overall, there is little to indicate a dependence for RNA:DNA hybrids forming co-transcriptionally, with results from the ribosomal DNA repeat unit instead supporting the intriguing model of RNA generating these structures in trans. The results of the study indicate heterogeneous functions of these genomic elements and new insights into their formation and stability in vivo.
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Project description:This SuperSeries is composed of the SubSeries listed below. Refer to individual Series
2015-06-15 | E-GEOD-68953 | biostudies-arrayexpress
Project description:Mapping of RNA:DNA hybrids in human cells reveals a number of characteristics of these non-canonical nucleic acid structures. A directional sequencing approach reveals the RNA component of the RNA:DNA hybrid to be purine-rich, indicating a thermodynamic contribution to the stability of these structures. The RNA:DNA hybrids are enriched at loci with decreased DNA methylation and increased DNase hypersensitivity, and within larger domains with characteristics of heterochromatin formation. Studies of chromatin at RNA:DNA hybrids shows the presence of the ILF2 and ILF3 transcription factors, supporting a model of certain transcription factors binding preferentially to the RNA:DNA conformation. Overall, there is little to indicate a dependence for RNA:DNA hybrids forming co-transcriptionally, with results from the ribosomal DNA repeat unit instead supporting a model of RNA generating these structures in trans. The results of the study indicate heterogeneous functions of these genomic elements and new insights into their formation and stability in vivo. Investigation of locatization of RNA in RNA:DNA hybrids genome-wide in HEK293T and IMR-90 cells through RNA:DNA hybrid immunorprecipitation strand-specific sequencing
2015-06-15 | E-GEOD-68948 | biostudies-arrayexpress
Project description:Mapping of RNA:DNA hybrids in human cells reveals a number of characteristics of these non-canonical nucleic acid structures. A directional sequencing approach reveals the RNA component of the RNA:DNA hybrid to be purine-rich, indicating a thermodynamic contribution to the stability of these structures. The RNA:DNA hybrids are enriched at loci with decreased DNA methylation and increased DNase hypersensitivity, and within larger domains with characteristics of heterochromatin formation. Studies of chromatin at RNA:DNA hybrids shows the presence of the ILF2 and ILF3 transcription factors, supporting a model of certain transcription factors binding preferentially to the RNA:DNA conformation. Overall, there is little to indicate a dependence for RNA:DNA hybrids forming co-transcriptionally, with results from the ribosomal DNA repeat unit instead supporting a model of RNA generating these structures in trans. The results of the study indicate heterogeneous functions of these genomic elements and new insights into their formation and stability in vivo. Investigation of expression data genome-wide in HEK293T and IMR-90 cells through RNA-seq, including rRNA
2015-06-15 | E-GEOD-68938 | biostudies-arrayexpress
Project description:Mapping of RNA:DNA hybrids in human cells reveals a number of characteristics of these non-canonical nucleic acid structures. A directional sequencing approach reveals the RNA component of the RNA:DNA hybrid to be purine-rich, indicating a thermodynamic contribution to the stability of these structures. The RNA:DNA hybrids are enriched at loci with decreased DNA methylation and increased DNase hypersensitivity, and within larger domains with characteristics of heterochromatin formation. Studies of chromatin at RNA:DNA hybrids shows the presence of the ILF2 and ILF3 transcription factors, supporting a model of certain transcription factors binding preferentially to the RNA:DNA conformation. Overall, there is little to indicate a dependence for RNA:DNA hybrids forming co-transcriptionally, with results from the ribosomal DNA repeat unit instead supporting a model of RNA generating these structures in trans. The results of the study indicate heterogeneous functions of these genomic elements and new insights into their formation and stability in vivo.
2015-06-15 | GSE68948 | GEO
Project description:Mapping of RNA:DNA hybrids in human cells reveals a number of characteristics of these non-canonical nucleic acid structures. A directional sequencing approach reveals the RNA component of the RNA:DNA hybrid to be purine-rich, indicating a thermodynamic contribution to the stability of these structures. The RNA:DNA hybrids are enriched at loci with decreased DNA methylation and increased DNase hypersensitivity, and within larger domains with characteristics of heterochromatin formation. Studies of chromatin at RNA:DNA hybrids shows the presence of the ILF2 and ILF3 transcription factors, supporting a model of certain transcription factors binding preferentially to the RNA:DNA conformation. Overall, there is little to indicate a dependence for RNA:DNA hybrids forming co-transcriptionally, with results from the ribosomal DNA repeat unit instead supporting a model of RNA generating these structures in trans. The results of the study indicate heterogeneous functions of these genomic elements and new insights into their formation and stability in vivo.
2015-06-15 | GSE68938 | GEO
Project description:RNA:DNA hybrids in the human genome have distinctive nucleotide characteristics, chromatin composition, and transcriptional relationships
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Project description:The p53-Mdm2 system is key to tumor suppression. We have recently reported that p53 as well as Mdm2 are capable of supporting DNA replication fork progression. On the other hand, we found that Mdm2 is a modifier of chromatin, modulating polycomb repressor complex (PRC)-driven histone modifications. Here we show that, similar to Mdm2 knockdown, the depletion of PRC members impairs DNA synthesis, as determined in fiber assays. In particular, the ubiquitin ligase and PRC1 component RNF2/Ring1B is required to support DNA replication, similar to Mdm2. Moreover, the Ring finger domain of Mdm2 is not only essential for its ubiquitin ligase activity, but also for proper DNA replication. Strikingly, Mdm2 overexpression can rescue RNF2 depletion with regard to DNA replication fork progression, and vice versa, strongly suggesting that the two ubiquitin ligases perform overlapping functions in this context. H2A overexpression also rescues fork progression upon depletion of Mdm2 or RNF2, but only when the ubiquitination sites K118/K119 are present. Depleting the H2A deubiquitinating enzyme BAP1 reduces the fork rate, suggesting that both ubiquitination and deubiquitination of H2A are required to support fork progression. The depletion of Mdm2 elicits the accumulation of RNA/DNA hybrids, suggesting R-loop formation as a mechanism of impaired DNA replication. Accordingly, RNase H overexpression or the inhibition of the transcription elongation kinase CDK9 each rescues DNA replication upon depletion of Mdm2 or RNF2. Taken together, our results suggest that chromatin modification by Mdm2 and PRC1 ensures smooth DNA replication through the avoidance of R-loop formation.
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Project description:While most cells in multicellular organisms carry the same genetic information, in each cell type only a subset of genes is being transcribed. Such differentiation in gene expression depends, for a large part, on the activation and repression of regulatory sequences, including transcriptional enhancers. Transcriptional enhancers can be located tens of kilobases from their target genes, but display characteristic chromatin and DNA features, allowing their identification by genome-wide profiling. Here we show that integration of chromatin characteristics can be applied to predict distal enhancer candidates in Zea mays, thereby providing a basis for a better understanding of gene regulation in this important crop plant.To predict transcriptional enhancers in the crop plant maize (Zea mays L. ssp. mays), we integrated available genome-wide DNA methylation data with newly generated maps for chromatin accessibility and histone 3 lysine 9 acetylation (H3K9ac) enrichment in young seedling and husk tissue. Approximately 1500 intergenic regions, displaying low DNA methylation, high chromatin accessibility and H3K9ac enrichment, were classified as enhancer candidates. Based on their chromatin profiles, candidate sequences can be classified into four subcategories. Tissue-specificity of enhancer candidates is defined based on the tissues in which they are identified and putative target genes are assigned based on tissue-specific expression patterns of flanking genes.Our method identifies three previously identified distal enhancers in maize, validating the new set of enhancer candidates and enlarging the toolbox for the functional characterization of gene regulation in the highly repetitive maize genome.
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Project description:One of the long-standing mysteries of evolutionary genomics is the source of the wide phylogenetic diversity in genome nucleotide composition (G?+?C versus A?+?T), which must be a consequence of interspecific differences in mutation bias, the efficiency of selection for different nucleotides or a combination of the two. We demonstrate that although genomic G?+?C composition is strongly driven by mutation bias, it is also substantially modified by direct selection and/or as a by-product of biased gene conversion. Moreover, G?+?C composition at fourfold redundant sites is consistently elevated above the neutral expectation-more so than for any other class of sites.
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