Gene Amplification Associated Overexpression of the RNA Editing Enzyme ADAR1 Enhances Human Lung Tumorigenesis
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE67660 | GEO | 2018/04/08
REPOSITORIES: GEO
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Project description:Aberrant RNA-editing was observed in several human tumors, but its significance is mostly unknown. Here we show that ADAR1, a ubiquitous RNA-editing enzyme, is commonly lost in metastatic melanoma cells and specimens. Experimental ADAR1 silencing significantly alters melanoma cell morphology, facilitates proliferation and cell-cycle, and increases the tumorigenicity in-vivo. A series of ADAR1 truncation mutants establishes a novel RNA-editing-independent role for ADAR1 in controlling the nuclear and cytoplasmic processing steps of miRNA biogenesis. Altered expression of ADAR1-controled miRNAs accounts for the observed phenotype. We show that the oncogenic miR-17-5p endogenously regulates ADAR1 expression and that its genomic sequence is frequently amplified in melanoma to overexpress the mature miR-17-5p form. ADAR1 and miR-17-5p are ubiquitously expressed, suggesting the generality of this mechanism. Melanoma cell line expressing low ADAR1 levels (ADAR1-Knockdown) using shRNA technique were selected for RNA extraction and hybridization on Affymetrix microarrays. We sought to examine the alterations in the genes and microRNA expression profile in the manipulated cell system, due to ADAR1 possible involvement cancer development. To that end, we selected ADAR1-knockdown (ADAR1-KD) cells that demonstrated an enhanced aggressive phenotype both in vivo and in vitro as compared to the control cells (Control).
2012-08-31 | E-GEOD-31963 | biostudies-arrayexpress
Project description:The ADAR RNA editing enzymes deaminate adenosine bases to inosines in cellular RNAs, recoding open reading frames. Human ADAR1 mutations cause Aicardi-Goutieres Syndrome (AGS) and Adar1 mutant mice showing an aberrant interferon response and death by embryonic day E12.5 model the human disease. Searches have not identified key ADAR1 RNA editing sites recoding immune/haematopoietic proteins but editing is widespread in Alu sequences. We show that Adar1 embryonic lethality is rescued in Adar1; Mavs double mutant mice in which general antiviral responses to cytoplasmic dsRNA are prevented. We propose that inosine bases are epigenetic marks identifying cellular RNA as innate immune ÒselfÓ. Consistent with this idea we show that an editing-active cytoplasmic ADAR is required to prevent aberrant immune responses in Adar1 mutant mouse embryo fibroblasts. No dramatic increase in repetitive transcripts is observed. AGS mutations in ADAR1 affect editing by the interferon-inducible cytoplasmic ADAR1 isoform. RNA-seq expression profiling in Adar1 and Adar1/Mavs knockout mice embryos.
2014-12-19 | E-GEOD-62917 | biostudies-arrayexpress
Project description:ADAR1 catalyzes Adenosine-to-Inosine (A-to-I) editing of double-stranded RNA and regulates global expression output through its interactions with RNA and other proteins. ADARs play important roles in development and disease, and previous work has shown that ADAR1 is oncogenic in a growing list of cancer types. Here we show that ADAR1 is important for growth and invasion in triple negative breast cancer cells, as ADAR1 loss yields reduced growth, migration & invasion, and mammosphere formation. Global RNA-seq analyses demonstrate that ADAR1 regulates both coding and non-coding targets via expression level and/or A-to-I editing. We demonstrated that a recoding edit in FLNB (chr3:58156064) inhibits the tumor suppressive activities of the protein to promote growth & invasion. We show that several tumor suppressor microRNAs are also downregulated by ADAR1 to promote cell cycle progression and invasion. This work describes several novel mechanisms of ADAR1-mediated oncogenesis in triple negative breast cancer, providing support to strategies for targeting ADAR1 in this aggressive cancer type with few treatment options.
2022-03-14 | GSE177056 | GEO
Project description:We used transgenic mouse embryos that are deficient in the two enzymatically active RNA editing enzymes ADAR1 and ADAR2 to compare relative frequencies but also sequence composition of mature miRNAs in these genetically modified backgrounds to wild-type mice by Illumina next gen sequencing. Deficiency of ADAR2 leads to a reproducible change in abundance of specific miRNAs and their predicted targets. Changes in miRNA abundance seem unrelated to editing events. Additional deletion of ADAR1 has surprisingly little impact on the mature miRNA repertoire, indicating that miRNA expression is primarily dependent on ADAR2. A to G transitions reflecting A to I editing events can be detected at few sites and at low frequency during the early embryonic stage investigated. Again, most editing events are ADAR2 dependent with only few editing sites being specifically edited by ADAR1. Besides known editing events in miRNAs a few novel, previously unknown editing events were identified. Some editing events are located to the seed region of miRNAs opening the possibility that editing leads to their retargeting. GSM852140-8: sequencing of mature miRNAs of wt, ADAR2-/- and ADAR1-/-/ADAR2-/- female mouse embryos at E11.5 GSM863778-81: Gene expression was measured in wiltype, ADAR2-/- and ADAR1-/-/ADAR2-/- E11.5 whole female mouse embryos using Agilent Whole Mouse Genome Oligo Microarrays 8x60K.
2012-02-02 | E-GEOD-34626 | biostudies-arrayexpress
Project description:Adenosine deaminases acting on RNA (ADAR) catalyze the conversion of adenosines into inosines (A-to-I), modifying a large proportion of cellular RNAs and associated with diverse cancers. We reported previously that ADAR1 is functionally important for thyroid cancer progression and A-to-I editing events are elevated in these tumors. However, the downstream effectors regulated or edited by ADAR1 and the significance of ADAR1 dysregulation in thyroid cancer remain unclear. Here we provide insight, by whole transcriptome sequencing, into the consequences of ADAR1 dysregulation on global gene expression, RNA splicing and RNA editing. Furthermore, we describe for the first time an oncogenic function for CDK13 in thyroid cancer and identified a new ADAR1-dependent RNA editing event that occurs in the coding region of its transcript. Moreover, CDK13 was significantly over-edited in tumor samples and our functional analysis revealed the importance of this specific editing event in promoting cancer cell hallmarks. Finally, we showed that the editing of CDK13 modifies its subcellular localization and that this event could explain, at least in part, the global change in splicing produced by ADAR1 dysregulation. In summary, our data reinforces A-to-I editing as an important pathway in cancer progression, identifying novel mechanisms that open new insights into future treatments in thyroid and other cancer types.
2021-09-15 | GSE165282 | GEO
Project description:We used CRISPR KI technology to mutagenize the cis-regulatory elements including the editing stem and the editing complementary sequence of three RNA editing substrates-NEIL1, TTYH2, AJUBA. We designed single nucleotide variants, double-nucleotide variants and other mutant isoforms to interrogate the primary sequence and the secondary structures around the endogenous RNA editing sites. Gene specific primers were used to make the NGS library for each locus. The unique mutation of each tested isoform can be used as barcode and RNA editing level can be measured for each isoform from the pooled library. We found that RNA sequence and structure features synergistically determine the editing levels. Several features, such as mutation number, free energy, and probability of active conformation, play an important role in determining editing efficiency. This study systematically investigated the contribution of cis-regulatory elements to ADAR1 RNA editing by combining CRISPR-based saturation mutagenesis and deep sequencing technology.
2020-06-01 | GSE138860 | GEO
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:ADARs are the primary factors underlying A-to-I editing in metazoans. We conducted the first global study of ADAR1-RNA interaction in human cells using CLIP-Seq. In contrast to the expected predominant binding of ADAR1 to Alu repeats, thousands of CLIP sites were located in non-Alu regions. This unexpectedly frequent non-Alu binding enabled discovery of transcriptome-wide functional and biophysical targets of ADAR1 in the regulation of mRNA processing including alternative 3' UTR usage and alternative splicing. In addition, a global analysis of ADAR1 binding to non-Alu regions also revealed its primary interaction with microRNA (miRNA) transcripts in the nucleus, which subsequently affected expression levels of mature miRNAs. A complex global picture was revealed regarding the dependence of this function on the double-stranded RNA binding domains or deaminase activity. Our study unfolded a broad landscape of the diverse functional roles of ADAR1. To identify ADAR binding dependent miRNA defferential expression profiles, U87MG cells were transfected with ADAR1 overexpression vector, RNA binding mutant (EAA and E912A), siRNA of ADAR1 or controls.
2015-03-11 | E-GEOD-55362 | biostudies-arrayexpress
Project description:The blossom of immunotherapy in melanoma highlights the need to delineate mechanisms of immune resistance. Recently, we have demonstrated that the RNA editing protein, adenosine deaminase acting on RNA-1 (ADAR1) is down-regulated during metastatic transition of melanoma, which enhances melanoma cell proliferation and tumorigenicity. Here we investigate the role of ADAR1 in melanoma immune resistance. Importantly, knockdown of ADAR1 in human melanoma cells induces resistance to tumor infiltrating lymphocytes in a cell contact-dependent mechanism. We show that ADAR1, in an editing-independent manner, regulates the biogenesis of miR-222 at the transcription level and thereby Intercellular Adhesion Molecule 1 (ICAM1) expression, which consequently affects melanoma immune resistance. ADAR1 thus has a novel, pivotal, role in cancer immune resistance. Corroborating with these results, the expression of miR-222 in melanoma tissue specimens was significantly higher in patients who had no clinical benefit from treatment with ipilimumab as compared to patients that responded clinically, suggesting that miR-222 could function as a biomarker for the prediction of response to ipilimumab. These results provide not only novel insights on melanoma immune resistance, but also pave the way to the development of innovative personalized tools to enable optimal drug selection and treatment. 13 formalin fixed paraffin embedded (FFPE) melanoma tissues were stained with hematoxilin and eosin for examination by an expert pathologist. Non-tumor tissue was removed. Total RNA was isolated using miRNeasy FFPE kit (Qiagen) according to the manufacture guidelines.
2015-12-31 | E-GEOD-67496 | biostudies-arrayexpress
Project description:Purpose: RNA editing by ADAR1 is essential for hematopoietic development. The goals of this study were firstly, to identify ADAR1-specific RNA-editing sites by indentifying A-to-I (G) RNA editing sites in wild type mice that were not edited or reduced in editing frequency in ADAR1 deficient murine erythroid cells. Secondly, to determine the transcription consequence of an absence of ADAR1-mediated A-to-I editing. Methods: Total RNA from E14.5 fetal liver of embryos with an erythroid restricted deletion of ADAR1 (KO) and littermate controls (WT), in duplicate. cDNA libraries were prepared and RNA sequenced using Illumina HiSeq2000. The sequence reads that passed quality filters were analyzed at the transcript level with TopHat followed by Cufflinks. qRTâPCR validation was performed using SYBR Green assays. A-to-I (G) RNA editing sites were identified as previously described by Ramaswami G. et al., Nature Methods, 2012 using BurrowsâWheeler Aligner (BWA) followed by ANOVA (ANOVA). RNA editing sites were confirmed by Sanger sequencing. Results: Using an optimized data analysis workflow, we mapped about 30 million sequence reads per sample to the mouse genome (build mm9) and identified 14,484 transcripts in the fetal livers of WT and ADAR1E861A mice with BWA. RNA-seq data had a goodness of fit (R2) of >0.7, p<0.0001 between biological duplicates per genotype. Clusters of hyper-editing were onserved in long, unannotated 3'UTRs of erythroid specific transcripts. A profound upregulation of interferon stimulated genes were found to be massively upregulated (up to 5 log2FC) in KO fetal liver compared to WT. 11.332 (6,894 novel) A-to-I RNA editing sites were identified when assessing mismatches in RNA-seq data. Conclusions: Our study represents the first detailed analysis of erythroid transcriptomes and A-to-I RNA editing sites, with biologic replicates, generated by RNA-seq technology. A-to-I RNA editing is the essential function of ADAR1 and is required to prevent sensing of endogenous transcripts, likely via a RIG-I like receptor mediated axis. Fetal liver mRNA profiles of E14.5 wild type (WT) and ADAR Epor-Cre knock out mice were generated by deep sequencing, in duplicate using Illumina HiSeq 2000.
2016-07-24 | E-GEOD-71042 | biostudies-arrayexpress