Comprehensive interrogation of the ADAR2 deaminase domain for engineering enhanced RNA base-editing activity, functionality and specificity
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE158656 | GEO | 2022/01/19
REPOSITORIES: GEO
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Project description:Comprehensive interrogation of the ADAR2 deaminase domain for engineering enhanced RNA base-editing activity, functionality and specificity
| PRJNA666136 | ENA
Project description:Adenosine deaminases acting on RNA (ADARs) can be repurposed to enable programmable RNA editing, however their exogenous delivery leads to transcriptome-wide off-targeting, and additionally, enzymatic activity on certain RNA motifs, especially those flanked by a 5' guanosine is very low thus limiting their utility as a transcriptome engineering toolset. Towards addressing these issues, we first performed a novel deep mutational scan of the ADAR2 deaminase domain, directly measuring the impact of every amino acid substitution across 261 residues, on RNA editing. This enabled us to create a domain-wide mutagenesis map while also revealing a novel hyperactive variant with improved enzymatic activity at 5'-GAN-3' motifs. As overexpression of ADAR enzymes, especially hyperactive variants, can lead to significant transcriptome-wide off-targeting, we next engineered a split-ADAR2 deaminase which resulted in >100-fold more specific RNA editing as compared to full-length deaminase overexpression. Taken together, we anticipate this systematic engineering of the ADAR2 deaminase domain will enable broader utility of the ADAR toolset for RNA biotechnology applications.
| S-EPMC8809894 | biostudies-literature
Project description:MicroRNA expression profile of NB U118 cells transfected with a plasmid directing an inactive Adar2 vs an active Adar2 - 3 biological replicates 1 Condition experiment, 3 biological replicates, 2 replicates/array
2015-02-28 | E-GEOD-63694 | biostudies-arrayexpress
Project description:MicroRNA expression profile of NB U118 cells transfected with a plasmid directing an inactive Adar2 vs an active Adar2 - 3 biological replicates
2015-02-28 | GSE63694 | GEO
Project description:Purpose: Measure gene expression and RNA editing changes in Adar-WT and Adar2-KO MEFs Methods: Performed PolyA+ RNA-seq (single end, one sample each) of Adar2-WT and Adar2-KO MEFs Results: Observed changes in editing and gene expression of several genes Conclusion: Adar2 influences gene expression and editing of transcripts
2016-12-23 | GSE74746 | GEO
Project description:To assess whether antiviral genes are upregulated by ADAR2 knockdown, we performed a comprehensive analysis using a microarray system for oligodendroglia cells introduced shRNA against ADAR2 or control. The inflammation- and immune response-related genes were upregulated in ADAR2-knockdown cells.
2019-10-17 | GSE138927 | GEO
Project description:Adenosine deaminases (ADARs) are RNA binding proteins that bind to double stranded RNA and convert adenosine to inosine. Editing creates multiple isoforms of neurotransmitter receptors, including AMPA-subtype Glutamate channels such as Gria2 that is edited to introduce a Q to R amino acid change. Adar2 knock out mice die of seizures shortly after birth, but if the Gria2 Q/R editing site is mutated to mimic the edited version then the animals are viable. We performed RNA-Seq on the frontal cortices of Adar2-/- Gria2R/R mice and their Adar2+/+ Gria2R/R littermates, quantifying overall gene expression, splicing, and A to I editing in a transcriptome-wide fashion. We found 56 editing sites whose level of editing was significantly diminished in the Adar2 deficient animals. The majority of Adar2 responsive editing sites were in the coding regions of genes. Interestingly, other than Adar2 expression, there were only two additional statistically significant differentially expressed genes, Flnb and Cdh13. There were also only three exons that showed statistically significant differences in expression levels between the two genotypes. This work illustrates that ADAR2 is important in site-specific changes of protein coding sequences but has only modest effects on gene expression or splicing in vivo. 6 ADAR2 Knock out frontal cortices and 6 litter mate control frontal cortices from male mice
2016-07-03 | E-GEOD-70588 | biostudies-arrayexpress
Project description:ADARs, short for adenosine deaminases acting on RNA, were first found by their characteristic activity of deaminating up to 50% of all adenosines in double-stranded RNA in vitro. C. elegans has two ADARs, only one is found in the fly, and mammals express three ADARs. Importantly, the spectrum of physiological roles of these enzymes in the different organisms remains largely unknown. ADARs are ~750-1150 amino acids in size, feature 2-3 N-terminal double-stranded RNA binding motifs, an enzymatic domain related to that of prokaryotic cytidine deaminases, and a ~190 residue extended C-terminal domain of unknown function. The mammalian ADARs are detectable in many if not all tissues, with relatively prominent expression in the central nervous system, predicting tissue- or cell type-specific tasks for the mammalian ADARs. Studies over the last decade collectively indicated that one function of ADARs is the editing of nuclear transcripts to introduce select amino acid substitutions in proteins. Arguably the best-studied example for this type of RNA editing (‘A-to-I editing’) in the mammal is performed by ADAR2 and occurs in primary transcripts for the GluA2 subunit (also known as GluR-B or GluR2 subunit) of AMPA receptors mediating fast excitatory neurotransmission. A particular glutamine codon (CAG) in the exonic sequence for the inner lining of the glutamate-activated AMPA receptor is converted by deamination of the central adenosine into an unusual arginine codon (CIG; the resultant inosine is seen as guanosine by the protein translation machinery). This substitution of the gene-encoded glutamine codon by the edited arginine codon is found in nearly 100% of all GluA2 cDNA derived from brain mRNA. RNA editing in this instance ensures that GluA2-containing AMPA receptors become impermeable to Ca2+. In addition to switching a key functional determinant in GluA2 to nearly 100%, ADAR2 has been implicated in generating numerous amino acid substitutions at lower levels in various mammalian neurotransmitter receptors and voltage-gated ion channels, primarily but not exclusively of nervous tissue. Most of these substitutions elicit distinct functional consequences, which led to the notion that site-selective RNA editing by ADAR2 may ensure the functional fine-tuning of the affected transmembrane proteins. Such fine-tuning should reflect the expansion of the protein sequence directed by the respective gene into sequence subpopulations, each differing in particular functional aspects, such as transmitter efficacy, desensitization, or voltage threshold. If this notion is correct, ADAR2 knockout should elicit phenotypes, which might range from subtle to severe, depending on the physiological role(s) of the ADAR2 targets in different tissues. ADAR2 knockout mice, however, die soon after birth from severe epileptic seizures, a consequence of the changed ion conductance properties of AMPA receptors containing unedited GluA2. Fortunately, mice lacking ADAR2 are robust and have normal life span if they carry GluA2 alleles genetically altered to contain the particular arginine codon for a Ca2+ impermeable ion channel pore of AMPA receptors, thus rescinding the need for ADAR2-mediated GluA2 transcript editing. These mice are thus eminently suitable to study the phenotypic consequences of failure to edit all ADAR2 targets excepting GluA2. We therefore tested cohorts of ADAR2-/-/GluA2(R)/(R) mice in 16 well-established paradigms for central and peripheral phenotypic abnormalities. We report that we found few differences to control mice (GluA2(R)/(R)) and hence, the lack of ADAR2 appears not to affect most of the physiological functions tested. Brain of four mutant animals of ADAR-/-/GluR-BR/R versus a pool of four reference (wildtype) mice; two technical replicates for each mutant mouse including a dye swap experiment - in total 8 chip hybridisations
2010-11-01 | E-GEOD-15383 | biostudies-arrayexpress
Project description:Purpose: A-to-I RNA editing is critical for many cellular processes. The sites of A-I RNA editing can be identified through RNA-seq and matching the reads to the annotated database like RADAR. The goals of this study is to compare A-I RNA editing profile among wild type, ADAR2 overexpressing and ADAR2+SRSF9 overexpressing 293T cells to evaluate the influence of SRSF9 repressive action on A-I RNA editing Methods: A-I RNA editing profile and gene expression profiles were generated by deep sequencing from all the samples, using NEBNext® Ultra™ Directional RNA Library Prep Kit. The sequence reads that passed quality filters were analyzed for identifying the A-I RNA editing sites using RADAR Database Results: Upon overexpression of ADAR2, we found that 18,174 sites were differentially edited compared to control cells, of which 97.0% showed a significant increase in their editing levels as expected (P < 0.05, Fisher’s test). Furthermore, when we overexpressed both ADAR2 and SRSF9 together, we found that 6,994 sites were differentially edited compared to overexpression of the deaminase alone (P < 0.05, Fisher’s test). Importantly, the editing of 92.5% of these sites was down-regulated, consistent with the function of SRSF9 as a repressor of editing. Conclusions: Our study reports a detailed analysis of the effect of SRSF9 on A-I RNA editing of ADAR2-specific targets. We Conclude that this SRSF9 regulon is significantly enriched for brain-specific editing sites despite our unbiased approach.
2018-06-21 | GSE114970 | GEO