Identification of immunogenic double-stranded RNAs in human cell lines
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE155964 | GEO | 2025/08/31
REPOSITORIES: GEO
Similar Datasets
Project description:The antiviral defense in vertebrates requires the innate immune system to sense foreign “non-self” nucleic acids while avoiding “self” nucleic acids, which is accomplished by an intricate system. Cellular double-stranded RNAs (dsRNAs) are edited by the RNA editing enzyme ADAR1 to prevent their dsRNA structure pattern from being recognized as viral dsRNA. Lack of RNA editing by ADAR1 enables activation of MDA5, a cytosolic dsRNA sensor, by cellular dsRNA. Additional RNA editing- independent functions of ADAR1 have been proposed, but the specific mechanism remains elusive. Here we demonstrate that RNA binding by ADAR1, independent of its editing activity, restricts the activation of PKR, another cytosolic dsRNA sensor, by cellular dsRNA. Mechanistically, the loss of ADAR1 editing caused MDA5 activation to induce interferon signaling, while a lack of ADAR1 protein or its dsRNA binding ability led to PKR activation, with subsequent stress granule formation and proliferation arrest. Based on these findings we rescued the Adar1−/− mice from embryonic lethality to adulthood by deleting both MDA5 and PKR, in contrast to the limited rescue of Adar1−/− mice by removing MDA5 or PKR alone. Our findings reveal a multifaceted contribution of ADAR1 in regulating the immunogenicity of “self” dsRNAs. Furthermore, ADAR1 is an immuno-oncology target for drug development, and the separation of ADAR1’s RNA editing and binding functions provides mechanistic insights for such developments.
2023-10-03 | GSE198386 | GEO
Project description:Adenosine-to-Inosine (A-to-I) editing of double stranded RNA (dsRNA) is an essential modifier of dsRNA immunogenicity. Loss of Adenosine deaminase acting on RNA 1 (ADAR1), or its A-to-I editing activity, triggers a lethal MDA5-dependent autoinflammatory response to endogenous unedited dsRNA. We performed a genome-wide suppressor screen to map the genetic landscape regulating the response to a loss of ADAR1 mediated A-to-I editing. This identified that the interacting proteins GGNBP2, CNOT10 and CNOT11 regulate immunogenic sensing following loss of A-to-I editing. GGNBP2 acts between transcription and cytoplasmic MDA5 sensing. Loss of GGNBP2 modified the distribution of dsRNA within cells, reducing the cytoplasmic dsRNA load and preventing induction of type I IFN and lethal autoinflammation. GGNBP2, CNOT10 and CNOT11 are novel regulators of the cellular response to unedited dsRNA.
2024-11-21 | GSE234570 | GEO
Project description:Endogenous double-stranded RNA (dsRNA) triggers pro-inflammatory signaling and has been shown to accumulate in Alzheimer’s disease (AD), but the origins of this dsRNA are incompletely understood. Transposable elements (TEs), which are non-coding DNA sequences capable of forming dsRNA, are a potential endogenous source of dsRNA in AD. We generated dsRNA immunoprecipitation (J2 dsRNA antibody) data on astrocytes treated with or without a siRNA to knock down the dsRNA editing enzyme ADAR1. We analyzed TE transcripts enriched in dsRNA pools when ADAR1 was knocked down, and we identified putative dsRNA-prone TEs, which were also present in secondary analyses of datasets profiling RNAs bound to PKR, MDA5, and the p110 isoform of ADAR1.
2025-07-25 | GSE303455 | GEO
Project description:Endogenous double-stranded RNA is prevented from activating the cytosolic antiviral receptor MDA5 by adenosine-to-inosine editing by ADAR. Consequently, CRISPR/cas9 targeting ADAR in the human monocytic cell line THP-1 induces a spontaneous MDA5-dependent interferon response. This response is synergistically enhanced by concomitant CRISPR/cas9 targeting of hnRNPC. For this study, cas9 transgenic THP-1 were nucleofected with combinations of control gRNA, ADAR gRNA or hnRNPC gRNA to elucidate the basis for synergistic interferon-stmulated gene induction by combined ADAR and hnRNPC targeting. As a control for interferon-stimulated gene induction, IFN-alpha treated THP-1 were included, as well. To investigate potential interferon inducing mechanisms, we quantified gene expression, intron expression as well as the expression of regions rich in adenosine-to-inosine editing clusters. In a second part, nuclear vs cytosolic distribution of RNA rich in adenosine-to-inosine clusters was investigated by sequencing of total RNA or RNA from cytosolic and nuclear extracts of ADAR and/or hnRNPC targeted cells. In the first part of the study, STING-deficient, cas9 transgenic THP-1 were nucleofected with combinations of control, GFP-targeting, ADAR-targeting or hnRNPC-targeting gRNA and cells collected for total RNA extraction on days three, four and five after nucleofection. In addition, another control-nucleofected sample was treated on day 3 for 24 h. The experiment was repeated three times leading to three replicates per condition. In the second part, WT cas9-transgenic THP-1 were nucleofected with combinations of control, ADAR-targeting or hnRNPC-targeting gRNA and cells were either collected for total RNA extraction or separated into digitonin-soluble (cytosolic) and digitonin-resistant (nuclear and mitochondrial) compartments and then RNA extracted. The experiment was repeated twice leading to two replicates per condition. Differential gene expression analysis confirmed synergistic induction of interferon-stimulated genes. RNA-seq analysis demonstrated dysregulation of Alu-containing introns in hnRNPC-deficient cells via utilization of unmasked cryptic splice sites, including introns containing ADAR-dependent A-to-I editing clusters or regions enriched in editing clusters (ECRs) in general. These putative MDA5 ligands showed reduced editing in the absence of ADAR, providing a plausible mechanism for the combined effects of hnRNPC and ADAR. Part 2 of the study confirmed cytosolic access of a subset of ECRs to the cytosol.
2021-07-16 | GSE176012 | GEO
Project description:Adenosine deaminases acting on RNA (Adar1 and Adar2) catalyze I-to-A RNA editing, a post-transcriptional mechanism involved in multiple cellular functions. The role of Adar1-dependent RNA editing in cardiomyocytes (CMs) remains unclear. Here we show that conditional deletion of Adar1 in CMs results in myocarditis progressively evolving into dilated cardiomyopathy and heart failure at only 6 months of age. Adar1 depletion drives activation of interferon signaling genes (ISGs) in the absence of apoptosis and cytokine activation, and reduces the hypertrophic response of CMs upon pressure overload. Interestingly, ablation of the cytosolic sensor MDA5 prevents cardiac ISG activation and delays disease onset, but does not rescue the long-term lethal phenotype elicited by conditional deletion of Adar1. Retention of a single catalytically inactive Adar1 allele in CMs, in combination with MDA5 depletion, however, completely restores the cardiac function and prevents heart failure. Finally, ablation of interferon regulatory factor 7 (Irf7) attenuates the phenotype of Adar1-deficient CMs to a similar extent as MDA5 depletion, highlighting Irf7 as the main regulator of the immune response triggered by lack of Adar1 in CMs.
2022-08-24 | PXD024974 | Pride
Project description:Adenosine-to-Inosine (A-to-I) editing of dsRNA by ADAR proteins is a pervasive feature of the epitranscriptome. There are estimated to be over 100 million potential A-to-I editing sites in humans and A-to-I editing can have varying consequences for gene expression. Whilst editing resulting in protein recoding defines the role of ADAR2, ADAR1 has been proposed to have both editing-dependent and -independent functions. The relative contribution of these putative functions to ADAR1 biology is unclear. We demonstrate that the absence of ADAR1-mediated editing is well tolerated when the cytosolic dsRNA sensor MDA5 is deleted. These mice have normal hematopoiesis, tissue patterning and life span. A direct comparison of the complete deletion of ADAR1 and the specific loss of A-to-I editing activity demonstrates that RNA editing is the only essential function of ADAR1 in adult mice. Therefore, preventing MDA5 substrate formation by endogenous RNA is the essential in vivo function of ADAR1-mediated editing.
2017-08-14 | GSE94387 | GEO
Project description:Adenosine-to-Inosine (A-to-I) editing of dsRNA by ADAR proteins is a pervasive feature of the epitranscriptome. There are estimated to be over 100 million potential A-to-I editing sites in humans and A-to-I editing can have varying consequences for gene expression. Whilst editing resulting in protein recoding defines the role of ADAR2, ADAR1 has been proposed to have both editing-dependent and -independent functions. The relative contribution of these putative functions to ADAR1 biology is unclear. We demonstrate that the absence of ADAR1-mediated editing is well tolerated when the cytosolic dsRNA sensor MDA5 is deleted. These mice have normal hematopoiesis, tissue patterning and life span. A direct comparison of the complete deletion of ADAR1 and the specific loss of A-to-I editing activity demonstrates that RNA editing is the only essential function of ADAR1 in adult mice. Therefore, preventing MDA5 substrate formation by endogenous RNA is the essential in vivo function of ADAR1-mediated editing.
2017-08-14 | GSE94386 | GEO
Project description:Adenosine-to-Inosine (A-to-I) editing of dsRNA by ADAR proteins is a pervasive feature of the epitranscriptome. There are estimated to be over 100 million potential A-to-I editing sites in humans and A-to-I editing can have varying consequences for gene expression. Whilst editing resulting in protein recoding defines the role of ADAR2, ADAR1 has been proposed to have both editing-dependent and -independent functions. The relative contribution of these putative functions to ADAR1 biology is unclear. We demonstrate that the absence of ADAR1-mediated editing is well tolerated when the cytosolic dsRNA sensor MDA5 is deleted. These mice have normal hematopoiesis, tissue patterning and life span. A direct comparison of the complete deletion of ADAR1 and the specific loss of A-to-I editing activity demonstrates that RNA editing is the only essential function of ADAR1 in adult mice. Therefore, preventing MDA5 substrate formation by endogenous RNA is the essential in vivo function of ADAR1-mediated editing.
2017-08-14 | GSE94388 | 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