Ontology highlight
ABSTRACT:
PROVIDER: PRJNA874842 | ENA |
REPOSITORIES: ENA
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Project description:The SNAP-ADAR tool enables precise and efficient A-to-I RNA editing in a guideRNA-dependent manner by applying the self-labeling SNAP-tag enzyme to generate RNA-guided editases in cell culture. Here, we extend this platform by combining the SNAP-tagged tool with further effectors steered by the orthogonal HALO-tag. Due to their small size (ca. 2 kb), both effectors are readily integrated into one genomic locus. We demonstrate selective and concurrent recruitment of ADAR1 and ADAR2 deaminase activity for optimal editing with extended substrate scope and moderate global off-target effects. Furthermore, we combine the recruitment of ADAR1 and APOBEC1 deaminase activity to achieve selective and concurrent A-to-I and C-to-U RNA base editing of endogenous transcripts inside living cells again with moderate global off-target effects. The platform should be readily transferable to further epitranscriptomic writers and erasers to manipulate epitranscriptomic marks in a programmable way with high molecular precision.
2021-06-09 | GSE160945 | GEO
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: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:Huge efforts are made to engineer safe and efficient genome editing tools. An alternative might be the harnessing of ADAR-mediated RNA editing. We now present the engineering of chemically optimized antisense oligonucleotides that recruit endogenous human ADARs to edit endogenous transcripts in a simple and programmable way, an approach we refer to as RESTORE. Notably, RESTORE was markedly precise, and there was no evidence for perturbation of the natural editing homeostasis. We applied RESTORE to a panel of standard human cell lines, but also to several human primary cells including hepatocytes. In contrast to other RNA and DNA editing strategies, this approach requires only the administration of an oligonucleotide, circumvents the ectopic expression of proteins, and thus represents an attractive platform for drug development. In this respect we have shown the repair of the PiZZ mutation causing α1-antitrypsin deficiency and the editing of phosphotyrosine 701 in STAT1.
2018-12-01 | GSE121573 | 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. 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: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:Adenosine to inosine (A-to-I) RNA editing occurs in a wide range of tissues and cell types and can be catalyzed by one of two adenosine deaminase acting on double stranded RNA enzymes, ADAR and ADARB1. Editing can impact both coding and non-coding regions of RNA, and in higher organisms, has been proposed to function in adaptive evolution. Neither the prevalence of A-to-I editing nor the role of either ADAR or ADARB1 has been examined in the context of germ cell development in mammals. Computational analysis of whole testis and cell type specific RNA-sequencing data followed by molecular confirmation demonstrated that A-to-I RNA editing occurs in both the germ line and in somatic Sertoli cells in two targets, Cog3 and Rpa1. Expression analysis demonstrated both Adar and Adarb1 were expressed in both Sertoli cells and in a cell-type dependent manner during germ cell development. Conditional ablation of Adar did not impact testicular RNA editing in either germ cells or Sertoli cells. Additionally, Adar ablation in either cell type did not have gross impacts on germ cell development or male fertility. In contrast, global Adarb1 knockout animals demonstrated a complete loss of A-to-I RNA editing in spite of normal germ cell development. Taken together, these observations demonstrate ADARB1 mediates A-to-I RNA editing in the testis and these editing events are dispensable for male fertility in an inbred mouse strain in the lab.
2016-12-24 | GSE92870 | 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