In vitro and in vivo models to predict ADAR RNA editing oligonucleotides potential in human liver tissue
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PROVIDER: PRJNA1299471 | ENA |
REPOSITORIES: ENA
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Project description:Liver-originated diseases remain a significant global health burden, with limited treatment options available. RNA therapeutics, particularly adenosine deaminase acting on RNA (ADAR)-mediated editing using editing oligonucleotides (EONs) offer a novel approach to address these unmet medical needs. This study evaluates in vitro and in vivo liver models to predict the therapeutic potential of chemically modified EONs in human liver tissue, using ACTB as target. Multiple liver models, including primary human hepatocytes (PHH), cancer-derived cell lines, and iPSC-derived hepatocytes in both 2D and 3D formats, were characterized for ADAR expression, liver functionality, and RNA editing efficiency. The results show consistent ADAR expression across most models, with 3D models, particularly PHH spheroids and liver microtissues, closely mimicking human liver tissue in gene expression and editing capacity. In vivo, non-human primate liver biopsies showed high levels of ACTB editing, consistent with findings from PHH models. These findings highlight the critical role of preclinical models in EON selection, where multiple factors must be carefully considered. A multimodel assessment utilizing composite scoring to comprehensively assess the key parameters seems to be the approach of choice to maximize translatability across preclinical models and increase the likelihood of success in clinical applications
2025-08-07 | GSE304242 | GEO
Project description:We used our previously published isASO-ID protocol to identify binders for two different adenosine deaminases acting on RNA- (ADAR-) recruiting antisense oligonucleotides (ONs). The ONs differed in their phosphorothioate content and their RNA editing potency and efficiency through the recruitment of endogenous ADAR. We aimed to get a first insight into the protein interactions of this new ON class since ON toxicity is largely defined by the protein interactions. The results will help to understand class-specific mechanisms for ON toxicity and thus to design safer ON drugs.
2025-07-31 | PXD066763 | Pride
Project description:Site-directed RNA editing is a promising and potentially safer alternative to genome editing. Previous methods have been developed that recruit the endogenously and ubiquitously expressed ADAR enzymes to initiate site-specific A-to-I edits, but often suffer from low efficacy or dependency on viral delivery. Chemically modified oligonucleotides may be a promising alternative, but the approach still lacks systematic in-depth studies. Furthermore, the best characterized platform uses stereo-pure backbone chemistry, which is not widely used, commercially unavailable and challenging to manufacture. Here, we report on single-stranded oligonucleotides of 30-60 nt length, which are fully chemically stabilized by applying commercially available, classical RNA drug modifications, like 2´-O-methyl, 2´-fluoro, and DNA on a stereo-random phosphate/phosphorothioate backbone. We demonstrate our so-called RESTORE 2.0 oligonucleotides to induce the correction of pathogenic point mutations, efficacy after GalNAc-mediated uptake into human primary hepatocytes, and proof of in-vivo efficacy in mice upon lipid nanoparticle-mediated delivery. The discovered design principles may increase the accessibility of site-directed RNA base editing to expand and support further research in this field. Here, the transcriptome-wide precision of our RNA editing ONs is tested by RNA Seq of treated NHA cells.
2025-07-28 | GSE303437 | 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: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: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 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: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:Adar-mediated A-to-I editing is required for establishment of embryonic body axes in zebrafish. To assess the effect of Adar KD and OE, uninjected wild-type and embryos injected with 1 ng of adar MO or 50 pg of adar mRNA were kept until desired developmental stage: 128-cell or 50% epiboly. Two replicates of 20 pooled embryos from each time point were isolated for RNA extraction. For the analysis at 12 hpf, a separate batch of uninjected control, as well as Adar KD and OE samples were generated in three replicates.
2022-08-02 | GSE182714 | GEO