Investigating the genetic basis of RNA Editing in humans
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE39167 | GEO | 2017/07/01
SECONDARY ACCESSION(S): PRJNA170210
REPOSITORIES: GEO
Similar Datasets
Project description:Adenosine deaminases, RNA specific (ADAR) are proteins that deaminate adenosine to inosine which is then recognized in translation as guanosine. To study the roles of ADAR proteins in RNA editing and gene regulation, we carried out DNA and RNA sequencing, RNA interference and RNA-immunoprecipitation in human B-cells. We also characterized the ADAR protein complex by mass spectrometry. The results uncovered over 60,000 sites where the adenosines (A) are edited to guanosine (G) and several thousand genes whose expression levels are influenced by ADAR. We also identified more than 100 proteins in the ADAR protein complex; these include splicing factors, heterogeneous ribonucleoproteins and several members of the dynactin protein family. Our findings show that in human B-cells, ADAR proteins are involved in two independent functions: A-to-G editing and gene expression regulation. In addition, we showed that other types of RNA-DNA sequence differences are not mediated by ADAR proteins, and thus there are co- or post-transcriptional mechanisms yet to be determined. Here we studied human B-cells where ADAR proteins (ADAR1 and ADAR2) are expressed but APOBECs are not. We identified the sequence differences between DNA and the corresponding RNA in B-cells from two individuals. Then, we carried out RNA interference, RNA-immunoprecipitation and next generation sequencing to determine the contribution of ADAR proteins in mediating A-to-G editing and other types of RNA-DNA sequence differences.
2013-09-20 | E-GEOD-38233 | biostudies-arrayexpress
Project description:The ADAR RNA editing enzymes deaminate adenosine bases to inosines in cellular RNAs, recoding open reading frames. Human ADAR1 mutations cause Aicardi-Goutieres Syndrome (AGS) and Adar1 mutant mice showing an aberrant interferon response and death by embryonic day E12.5 model the human disease. Searches have not identified key ADAR1 RNA editing sites recoding immune/haematopoietic proteins but editing is widespread in Alu sequences. We show that Adar1 embryonic lethality is rescued in Adar1; Mavs double mutant mice in which general antiviral responses to cytoplasmic dsRNA are prevented. We propose that inosine bases are epigenetic marks identifying cellular RNA as innate immune ÒselfÓ. Consistent with this idea we show that an editing-active cytoplasmic ADAR is required to prevent aberrant immune responses in Adar1 mutant mouse embryo fibroblasts. No dramatic increase in repetitive transcripts is observed. AGS mutations in ADAR1 affect editing by the interferon-inducible cytoplasmic ADAR1 isoform. RNA-seq expression profiling in Adar1 and Adar1/Mavs knockout mice embryos.
2014-12-19 | E-GEOD-62917 | biostudies-arrayexpress
Project description:Adenosine deaminases, RNA specific (ADAR) are proteins that deaminate adenosine to inosine which is then recognized in translation as guanosine. To study the roles of ADAR proteins in RNA editing and gene regulation, we carried out DNA and RNA sequencing, RNA interference and RNA-immunoprecipitation in human B-cells. We also characterized the ADAR protein complex by mass spectrometry. The results uncovered over 60,000 sites where the adenosines (A) are edited to guanosine (G) and several thousand genes whose expression levels are influenced by ADAR. We also identified more than 100 proteins in the ADAR protein complex; these include splicing factors, heterogeneous ribonucleoproteins and several members of the dynactin protein family. Our findings show that in human B-cells, ADAR proteins are involved in two independent functions: A-to-G editing and gene expression regulation. In addition, we showed that other types of RNA-DNA sequence differences are not mediated by ADAR proteins, and thus there are co- or post-transcriptional mechanisms yet to be determined.
2013-09-20 | GSE38233 | GEO
Project description:The ADAR RNA editing enzymes deaminate adenosine bases to inosines in cellular RNAs, recoding open reading frames. Human ADAR1 mutations cause Aicardi-Goutieres Syndrome (AGS) and Adar1 mutant mice showing an aberrant interferon response and death by embryonic day E12.5 model the human disease. Searches have not identified key ADAR1 RNA editing sites recoding immune/haematopoietic proteins but editing is widespread in Alu sequences. We show that Adar1 embryonic lethality is rescued in Adar1; Mavs double mutant mice in which general antiviral responses to cytoplasmic dsRNA are prevented. We propose that inosine bases are epigenetic marks identifying cellular RNA as innate immune ÒselfÓ. Consistent with this idea we show that an editing-active cytoplasmic ADAR is required to prevent aberrant immune responses in Adar1 mutant mouse embryo fibroblasts. No dramatic increase in repetitive transcripts is observed. AGS mutations in ADAR1 affect editing by the interferon-inducible cytoplasmic ADAR1 isoform.
2014-12-19 | GSE62917 | GEO
Project description:High-throughput sequencing screens suggest that RNA editing, which consists in the substitution of adenosine with inosine by the RNA-specific adenosine deaminase (ADAR) enzyme, occurs at several thousand positions across the human genome. Recent evidences have shown that RNA-editing could promote proliferation and carcinogenesis; however, the general principles of ADAR activity on the transcriptome and how ADAR is controlled in cancers remain to be established. The main aim of this project was to investigate the phenomenon of RNA editing in breast and other cancers. The frequency of A-to-I editing was evaluated in 58 breast cancers equally distributed among the different molecular subtypes and 10 normal breast tissues. The analysis was focused on defining: the relationship between the global amount of editing and ADAR expression; the ability to predict the level of editability of specific sites; the distribution of editing in normal and tumour samples and among different breast cancer subtypes; and the clinical, pathological and genomic factors affecting editing.
| EGAS00001000495 | EGA
Project description:Alternative mRNA splicing is a major mechanism for gene regulation and transcriptome diversity. Despite the extent of the phenomenon, the regulation and specificity of the splicing machinery are only partially understood. Adenosine-to-inosine (A-to-I) RNA editing of pre-mRNA by ADAR enzymes has been linked to splicing regulation in several cases. Here we used bioinformatics approaches, RNA-seq and exon-specific microarray of ADAR knockdown cells to globally examine how ADAR and its A-to-I RNA editing activity influence alternative mRNA splicing. Although A-to-I RNA editing only rarely targets canonical splicing acceptor, donor, and branch sites, it was found to affect splicing regulatory elements (SREs) within exons. Cassette exons were found to be significantly enriched with A-to-I RNA editing sites compared with constitutive exons. RNA-seq and exon-specific microarray revealed that ADAR knockdown in hepatocarcinoma and myelogenous leukemia cell lines leads to global changes in gene expression, with hundreds of genes changing their splicing patterns in both cell lines. This global change in splicing pattern cannot be explained by putative editing sites alone. Genes showing significant changes in their splicing pattern are frequently involved in RNA processing and splicing activity. Analysis of recently published RNA-seq data from glioblastoma cell lines showed similar results. Our global analysis reveals that ADAR plays a major role in splicing regulation. Although direct editing of the splicing motifs does occur, we suggest it is not likely to be the primary mechanism for ADAR-mediated regulation of alternative splicing. Rather, this regulation is achieved by modulating trans-acting factors involved in the splicing machinery. HepG2 and K562 cell lines were stably transfected with plasmids containing siRNA designed to specifically knock down ADAR expression (ADAR KD). This in order to examine how ADAR affects alternative splicing globally.
2013-06-15 | E-GEOD-47945 | biostudies-arrayexpress
Project description:Alternative mRNA splicing is a major mechanism for gene regulation and transcriptome diversity. Despite the extent of the phenomenon, the regulation and specificity of the splicing machinery are only partially understood. Adenosine-to-inosine (A-to-I) RNA editing of pre-mRNA by ADAR enzymes has been linked to splicing regulation in several cases. Here we used bioinformatics approaches, RNA-seq and exon-specific microarray of ADAR knockdown cells to globally examine how ADAR and its A-to-I RNA editing activity influence alternative mRNA splicing. Although A-to-I RNA editing only rarely targets canonical splicing acceptor, donor, and branch sites, it was found to affect splicing regulatory elements (SREs) within exons. Cassette exons were found to be significantly enriched with A-to-I RNA editing sites compared with constitutive exons. RNA-seq and exon-specific microarray revealed that ADAR knockdown in hepatocarcinoma and myelogenous leukemia cell lines leads to global changes in gene expression, with hundreds of genes changing their splicing patterns in both cell lines. This global change in splicing pattern cannot be explained by putative editing sites alone. Genes showing significant changes in their splicing pattern are frequently involved in RNA processing and splicing activity. Analysis of recently published RNA-seq data from glioblastoma cell lines showed similar results. Our global analysis reveals that ADAR plays a major role in splicing regulation. Although direct editing of the splicing motifs does occur, we suggest it is not likely to be the primary mechanism for ADAR-mediated regulation of alternative splicing. Rather, this regulation is achieved by modulating trans-acting factors involved in the splicing machinery. HepG2 and K562 cell lines were stably transfected with plasmids containing siRNA designed to specifically knock down ADAR expression (ADAR KD). This in order to examine how ADAR affects alternative splicing globally.
2013-06-17 | E-GEOD-47997 | biostudies-arrayexpress
Project description:The RNA editing enzyme ADAR chemically modifies adenosine (A) to inosine (I), which is interpreted by the ribosome as a guanosine. Here we assess cotranscriptional A-to-I editing in Drosophila, by isolating nascent RNA from adult fly heads and subjecting samples to high-throughput sequencing. There are a large number of edited sites within nascent exons. Nascent RNA from an ADAR null mutant strain was also sequenced, indicating that almost all A-to-I events require ADAR. Moreover, mRNA editing levels correlate with editing levels within the cognate nascent RNA sequence, indicating that the extent of editing is set cotranscriptionally. Surprisingly, the nascent data also identify an excess of intronic over exonic editing sites. These intronic sites occur preferentially within introns that are poorly spliced cotranscriptionally, suggesting a link between editing and splicing. We conclude that ADAR-mediated editing is more widespread than previously indicated and largely occurs cotranscriptionally. GSM914095: Fly genomic DNA sequencing. Sequenced on the Illumina GA II. GSM914102-GSM914113: Fly head nascent RNA profiles over 6 time points of a 12hr light:dark cycle in duplicate; sequenced on the Illumina GA II. GSM914114-GSM914119: Fly head nascent RNA profiles of yw, FM7, ADAR0 males in duplicate; sequenced on the HiSeq2000. GSM915213-GSM915214: Fly head mRNA profiles over 2 time points of a 12hr light:dark cycle; sequenced on the Illumina GA II. GSM915215-GSM915220: Fly head mRNA profiles over 6 time points of a 12hr light:dark cycle; paired-end sequenced on the Illumina GA II. GSM915221-GSM91526: Fly head mRNA profiles over 6 time points of a 12hr light:dark cycle; sequenced on the Illumina GA II.
2012-05-31 | E-GEOD-37232 | biostudies-arrayexpress
Project description:Adenosine to inosine (A-to-I) RNA editing is a highly conserved regulatory process carried out by adenosine deaminases (ADARs) on dsRNAs. Although a significant fraction of the transcriptome is edited, the function of most editing sites is unknown. Previous studies indicated changes in A-to-I RNA editing frequencies following exposure to several stress types. However, the overall effect of stress on the expression of ADAR targets is not fully understood. Here we performed high-throughput RNA sequencing of wildtype and ADAR mutant C. elegans worms after heat shock, to analyze the effect of heat shock stress on the expression pattern of genes. We found that ADAR regulation following heat shock does not involve directly heat shock related genes. Our analysis also revealed that, lncRNAs and pseudogenes, which have a tendency for secondary RNA structures, are enriched among upregulated genes upon heat shock in ADAR mutant worms, while they are downregulated in ADAR mutant worms under permissive conditions. Therefore, temperature increases may destabilize dsRNA structures and protect them from RNAi degradation, despite the lack of ADAR function. These findings shade a new light on the dynamics of gene expression under heat shock in relation to ADAR function.
2018-12-12 | GSE122015 | GEO
Project description:The RNA editing enzyme ADAR chemically modifies adenosine (A) to inosine (I), which is interpreted by the ribosome as a guanosine. Here we assess cotranscriptional A-to-I editing in Drosophila, by isolating nascent RNA from adult fly heads and subjecting samples to high-throughput sequencing. There are a large number of edited sites within nascent exons. Nascent RNA from an ADAR null mutant strain was also sequenced, indicating that almost all A-to-I events require ADAR. Moreover, mRNA editing levels correlate with editing levels within the cognate nascent RNA sequence, indicating that the extent of editing is set cotranscriptionally. Surprisingly, the nascent data also identify an excess of intronic over exonic editing sites. These intronic sites occur preferentially within introns that are poorly spliced cotranscriptionally, suggesting a link between editing and splicing. We conclude that ADAR-mediated editing is more widespread than previously indicated and largely occurs cotranscriptionally.
2012-05-31 | GSE37232 | GEO