Ontology highlight
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PROVIDER: PRJNA1163502 | ENA |
REPOSITORIES: ENA
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Project description:RNA base editing represents a promising alternative for genome editing. Recent approaches harness the endogenous RNA editing enzyme ADAR to circumvent problems related to the ectopic expression of an editing enzyme, but they suffer from sequence restriction, lack of efficiency, and bystander editing. Here, we present in‐silico optimized CLUSTER guide RNAs, which bind their target mRNAs in a multivalent fashion and thereby enable editing with unprecedented precision as shown by next generation sequencing. CLUSTER guide RNAs can be genetically encoded and manufactured into viruses to work in various cell lines. They achieve on‐target editing on endogenous transcripts like GUSB and NUP43 with yields up to 45% without bystander editing and have been shown to recruit endogenous ADAR in vivo. The CLUSTER approach tremendously enlarges the sequence space available for guide RNA design and opens new avenues for drug development in the field of RNA base editing.
2021-09-20 | GSE184244 | GEO
Project description:Adenosine-to-inosine RNA base editing is a strategy developed to safely manipulate genetic information at the RNA level. Particularly promising for clinical implementation is the use of the ubiquitously expressed endogenous editing enzyme ADAR (adenosine deaminase acting on RNA) with tailored guide RNAs. However, the precision of editing could be compromised by global off-target events that can potentially occur throughout the transcriptome. In this study, we introduce a novel circular CLUSTER guide RNA design that recruits endogenous ADAR in vivo. The goals of the whole transcriptome sequencing experiment were to evaluate the A-to-G RNA editing index and the global editing precision of this novel design. To achieve this, Rett syndrome mice harboring a Mecp2 W104Amber mutation were treated either with a circular CLUSTER guide RNA targeting the mutant Mecp2 transcript or a scrambled and thus non-targeting control guide RNA. Both the targeting and the non-targeting guide RNA were encoded as AAV and delivered via retro-orbital injection of 4x10^12 viral genomes per mouse. The used AAV serotype PHP.eB allows cargo delivery to the mouse brain after systemic administration. Four weeks after injection the thalamus was isolated for NGS analysis. Whole transcriptome sequencing showed that the A-to-G RNA editing index was unaffected by treatment with the targeting guide RNA compared to the scrambled non-targeting control. We were unable to identify any global off-target events, excluding mouse to mouse variability, which suggests a very high precision of our approach on the transcriptome-wide level. Harnessing endogenous ADAR with permanent, AAV-driven CLUSTER guide RNAs in the CNS is an important next step towards the development of novel drug modalities that fight neurological diseases.
2024-06-27 | GSE265898 | GEO
Project description:RNA editing can be a promising therapeutic approach. However, ectopic expression of RNA editing enzymes was found to trigger off-target editing, and the recruitment of endogenous adenosine deaminase acting on RNA (ADAR) suffers from low efficiency and fluctuating ADAR expression. Here, we identified ADAR inhibitors (ADIs) that suppressed the activity of the fused ADAR2 deaminase domain (ADAR2DD). Using ADI, we developed an RNA transformer adenine base editor (RtABE) with both high specificity and high efficiency. With the fusion of ADI to ADAR2DD, RtABE remains inactive until it binds its target site. After binding to the target site, ADI is cleaved from ADAR2DD and RtABE becomes active. RtABE induced efficient on-target editing in various cells with different ADAR expression levels. Delivering RtABE via an adeno-associated virus enabled up to a 45% RNA correction rate in Hurler syndrome mice with no significant off-target editing, and -L-iduronidase activity was restored. RtABE is a highly specific and efficient RNA editing system with broad applicability.
2025-02-06 | GSE267726 | GEO
Project description:RNA base editing applies endogenous or engineered adenosine deaminases to introduce adenosine-to-inosine changes into a target RNA in a highly programmable manner. Recently, notable success was achieved for the repair of disease-causing guanosine-to-adenosine mutations by means of RNA base editing. Here, we propose that RNA base editing could be broadly applied to perturb protein function by removal of regulatory sites of post-translational modification (PTM), like phosphorylation and/or acetylation sites. We demonstrate the feasibility of PTM interference (PTMi) on more than 70 PTM sites in various signaling proteins and identify key determinants for high editing efficiency and potent down-stream effects. Specifically, we demonstrate both negative and positive regulation of the JAK/STAT pathway by PTMi. To identify potent regulatory sites for PTMi, we applied an improved version of the SNAP-ADAR tool, which achieved high editing efficiency over a broad codon scope with tight control of bystander editing. The transient nature of RNA base editing enables the fast, dose-dependent (thus partial) and reversible manipulation of PTM sites, which is a key advantage over DNA editing approaches, where genetic compensation or lethality can conceal a phenotype. In summary, PTM interference might become a valuable field of application of RNA base editing in basic biology and medicine.
2024-04-19 | GSE264114 | GEO
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:Exogenous RNA, such as circRNA, could be edited by endogenous editors, such as C-to-U editor activation-induced deaminase and apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like (AID/APOBEC), and A-to-I editor Adenosine deaminases acting on RNA (ADAR) (I: inosine, recognized as G). Editing of circRNA may interfere with IRES and Kozak sequence to initiate antigen translation, and may alter antigen products or mutate stop codons.
2023-12-31 | GSE221086 | 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:Cellular RNAs containing double-stranded RNA (dsRNA) structures are subject to A-to-I RNA editing by the adenosine deaminases that act on RNA (ADARs). While A-to-I editing can alter mRNA coding potential, most editing is observed in non-coding sequences, the function of which remains poorly characterized. Using a dsRNA immunoprecipitation and high-thoughput sequencing (dsRIP-Seq) approach, we identify 1523 expressed A-to-I edited regions and characterize their expression during Caenorhabditis elegans development. We observe that edited regions are highly expressed in early development and are closely associated with protein-coding genes. Edited dsRNA structures give rise to abundant small interfering RNAs (siRNAs) that are negatively correlated with ADAR expression and regulate the developmental expression of associated genes.
2018-02-23 | GSE79375 | GEO
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