GO:0003726 double-stranded RNA adenosine deaminase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0003726 describes the catalytic conversion of adenosine to inosine within double-stranded RNA, a reaction that diversifies the transcriptome and prevents innate immune sensing of self-RNA.
• The principal human enzyme carrying this activity is ADAR1, which exists as a constitutively expressed p110 isoform and an interferon-inducible p150 isoform.
• ADAR1-mediated A-to-I editing is essential for embryonic development and for suppressing MDA5- and PKR-driven autoinflammation.
• Loss of ADAR1 activity unleashes double-stranded RNA sensors, causing translational shutdown, necroptosis, and severe immunopathology.
• The activity is dysregulated in cancers, where it can mask immunotherapeutic responses, and in inflammatory conditions such as sepsis and morphine tolerance.
• CRISPR-based knockout, point-mutation, knock-in, and overexpression models are central to dissecting ADAR1 isoform-specific functions and editing-dependent versus editing-independent roles.
Description
GO:0003726, double-stranded RNA adenosine deaminase activity, is a molecular function that catalyzes the hydrolytic deamination of adenosine to inosine within double-stranded RNA (dsRNA). This reaction, commonly called A-to-I editing, is one of the most abundant post-transcriptional modifications in metazoans and is essential for maintaining the distinction between self and non-self RNA. The activity is encoded primarily by the ADAR gene family, with ADAR1 being the dominant dsRNA-specific enzyme in humans. Because inosine is read as guanosine by the translational machinery, editing can alter codon identity, splice sites, and RNA secondary structure, thereby expanding proteome diversity and modulating RNA stability. Beyond its role in normal physiology, this activity is a critical checkpoint against autoimmunity, as its loss leads to fatal interferonopathies in mice and humans. Researchers study GO:0003726 to understand innate immune tolerance, cancer immunology, and the development of RNA-editing therapeutics.
double-stranded RNA adenosine deaminase activity At A Glance
| GO ID | GO:0003726 |
|---|---|
| GO term | double-stranded RNA adenosine deaminase activity |
| Ontology | molecular_function |
| Synonym | double-stranded RNA specific editase activity |
| Major function | Catalyzes adenosine-to-inosine deamination in double-stranded RNA |
| Reaction | adenosine + H2O = inosine + NH4+ |
| Substrate | Double-stranded RNA containing adenosine |
| Product | Inosine-containing double-stranded RNA and ammonium |
| Representative enzyme | ADAR1 (encoded by ADAR) |
What Is GO:0003726?
In plain terms, GO:0003726 is the enzyme activity that changes the letter A to the letter I in double-stranded RNA. The QuickGO definition states: Catalysis of the reaction: adenosine + H2O = inosine + NH4+, in a double-stranded RNA molecule. This activity requires a double-stranded RNA substrate and produces inosine and ammonium as products. It is synonymous with double-stranded RNA specific editase activity and is classified under the molecular_function ontology aspect.
Why Is double-stranded RNA adenosine deaminase activity Important in Cell Biology?
GO:0003726 is important because it defines the biochemical activity that allows cells to chemically modify their own double-stranded RNA, thereby preventing aberrant activation of innate immune sensors such as MDA5, PKR, and ZBP1. This editing activity is also a source of transcriptomic and proteomic diversity, influencing processes ranging from embryonic development to cancer immune evasion. Dysregulation of this activity is directly linked to severe human diseases, including Aicardi-Goutieres syndrome-like interferonopathies, sepsis-associated lung injury, and resistance to cancer immunotherapy. Consequently, understanding and manipulating this activity is a major goal in immunology, oncology, and RNA therapeutics.
• Prevents autoinflammation by marking endogenous dsRNA as self, avoiding MDA5 and PKR activation.
• Supports embryonic development and hematopoietic homeostasis, as ADAR1 loss is embryonically lethal in mice.
• Modulates cancer immunogenicity and can mask the therapeutic promise of ZBP1-driven necroptosis.
• Protects pulmonary macrophages from sepsis-induced pyroptosis and lung injury.
• Contributes to pain sensitization through exosomal dsRNA-TLR3 signaling in morphine tolerance.
• Provides a basis for RNA-guided RNA editing tools derived from Cas9 and IscB.
• Serves as a biomarker and therapeutic target in interferonopathies and autoimmune diseases.
• Enables functional interrogation of isoform-specific ADAR1 roles using CRISPR models.
Molecular Mechanism of double-stranded RNA adenosine deaminase activity
Substrate recognition and double-stranded RNA binding
In simple terms: The enzyme first grabs onto double-stranded RNA.
ADAR1 contains multiple double-stranded RNA-binding domains that recognize A-form dsRNA without strict sequence specificity, allowing it to survey the transcriptome for editing sites. This binding is essential for positioning the catalytic domain over target adenosines and is a prerequisite for the deamination reaction defined by GO:0003726.
Catalytic deamination of adenosine to inosine
In simple terms: The enzyme chemically changes adenosine into inosine.
The catalytic domain of ADAR1 hydrolyzes the C6 amino group of adenosine, replacing it with a carbonyl oxygen to form inosine and releasing ammonium, exactly as described by the GO:0003726 reaction. Because inosine base-pairs with cytosine, this change can alter RNA secondary structure and is interpreted as guanosine during translation.
Isoform-specific regulation by ADAR1 p150 and p110
In simple terms: Two versions of the enzyme do related but distinct jobs.
The interferon-inducible p150 isoform is primarily cytoplasmic and is critical for preventing MDA5 activation, whereas the constitutively expressed p110 isoform is largely nuclear and protects against PKR activation. These distinct mechanisms avert fatal autoinflammation and highlight that GO:0003726 activity is deployed in a compartment-specific manner.
Editing-independent functions and protein interactions
In simple terms: The enzyme can also do things without editing RNA.
Beyond its catalytic activity, ADAR1 can interact with other proteins and influence cellular processes independently of deamination, complicating the interpretation of loss-of-function phenotypes. For example, ADAR1 masks ZBP1-driven necroptosis in cancer cells through mechanisms that may not require its editing activity.
Downstream consequences for innate immune sensing
In simple terms: Editing prevents the immune system from attacking our own RNA.
When GO:0003726 activity is reduced, endogenous dsRNA accumulates and activates MDA5, PKR, and ZBP1, leading to translational shutdown, necroptosis, and autoinflammation. This surveillance system is so sensitive that even partial loss of ADAR1 activity can trigger severe immunopathology.
Key Genes Involved in GO:0003726 double-stranded RNA adenosine deaminase activity
The following genes and proteins are central to the study of GO:0003726, either as catalytic enzymes, regulatory partners, or downstream effectors of dsRNA sensing.
| Gene | Major Role | Research Relevance |
|---|---|---|
| ADAR | Encodes ADAR1, the principal dsRNA adenosine deaminase | Core enzyme for GO:0003726; knockout causes embryonic lethality and autoinflammation |
| ADARB1 | Encodes ADAR2, a related editing enzyme with different substrate preferences | Comparative studies of editing specificity and neurological function |
| MDA5 (IFIH1) | Cytosolic dsRNA sensor | Mediates interferon response when ADAR1 editing is lost |
| PKR (EIF2AK2) | dsRNA-activated kinase | Triggers translational shutdown upon unedited dsRNA accumulation |
| ZBP1 | Z-nucleic acid sensor | Drives necroptosis when ADAR1 fails to mask dsRNA |
| MAVS | Mitochondrial antiviral signaling adaptor | Downstream of MDA5 in interferon induction |
| TLR3 | Endosomal dsRNA sensor | Implicated in exosomal dsRNA signaling and morphine tolerance |
| NF-kB | Transcription factor | Activated downstream of dsRNA sensing in inflammatory contexts |
| miR-21 | MicroRNA | Linked to ADAR1-mediated protection in sepsis via A20 signaling |
| A20 (TNFAIP3) | NF-kB inhibitor | Effector in ADAR1-dependent anti-inflammatory pathway |
| ISG15 | Interferon-stimulated gene | Marker of interferonopathy in ADAR1 deficiency |
| IFNAR1 | Type I interferon receptor | Required for interferonopathy phenotypes in ADAR1 loss |
| Cas9 | RNA-guided nuclease | Engineered into RNA-guided RNA editors for programmable editing |
| IscB | OMEGA nuclease | Converted into RNA-guided RNA editors, expanding editing tools |
| APOBEC | Cytidine deaminase family | Related deaminase used in base editing and RNA editing constructs |
| DROSHA | Microprocessor component | Affects dsRNA structures that are ADAR1 substrates |
| DICER | dsRNA-processing enzyme | Interplays with ADAR1 in small RNA biogenesis |
| STING | Cytosolic DNA sensor | Can crosstalk with dsRNA sensing pathways in inflammation |
How Is double-stranded RNA adenosine deaminase activity Regulated?
The activity of GO:0003726 is regulated at multiple levels. ADAR1 p150 is interferon-inducible, linking its expression to innate immune activation, while p110 is constitutively expressed. Post-translational modifications and protein-protein interactions further modulate ADAR1 function, and its localization to the nucleus or cytoplasm determines which dsRNA substrates are accessible. Additionally, the availability of dsRNA structures, which can be influenced by other RNA-binding proteins and by the interferon response itself, shapes the landscape of editing. This multilayered regulation ensures that A-to-I editing is tuned to cellular state and immune context.
double-stranded RNA adenosine deaminase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| ADAR | Aicardi-Goutieres syndrome, interferonopathy | Knockout and point-mutation iPSC-derived macrophages |
| ADAR | Cancer immunotherapy resistance | Syngeneic tumor models with Adar1 knockout |
| ADAR | Sepsis-induced lung injury | LPS-induced sepsis model in macrophage-specific knockout mice |
| TLR3 | Morphine tolerance and hyperalgesia | Exosome transfer and TLR3 knockout mice |
| MDA5 (IFIH1) | Autoinflammatory interferonopathy | MDA5 knockout in ADAR1-deficient backgrounds |
Autoinflammatory interferonopathies
Loss-of-function mutations in ADAR cause Aicardi-Goutieres syndrome and related interferonopathies characterized by chronic type I interferon signaling. ADAR1p150 prevents MDA5 and PKR activation via distinct mechanisms, and its absence leads to fatal autoinflammation in mouse models. These findings establish GO:0003726 as a critical safeguard against innate immune self-reactivity.
Cancer immunology and immunotherapy resistance
ADAR1 editing can mask the cancer immunotherapeutic promise of ZBP1-driven necroptosis, and its loss sensitizes tumors to immune attack. This positions GO:0003726 as a potential target for combination immunotherapies, though careful isoform-specific targeting is needed to avoid toxicity.
Sepsis and inflammatory lung injury
ADAR1 protects pulmonary macrophages from sepsis-induced pyroptosis and lung injury through miR-21/A20 signaling, indicating that this editing activity restrains excessive inflammation in acute settings. Targeting this pathway may offer therapeutic benefit in sepsis.
Pain and neuroimmune interactions
Exosomal double-stranded RNA-TLR3 signaling contributes to morphine tolerance and hyperalgesia, and modulating this pathway attenuates these effects. This suggests that dsRNA metabolism, potentially including GO:0003726 activity, influences neuroimmune pain processing.
From double-stranded RNA adenosine deaminase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does ADAR1 catalytic activity suppress autoinflammation? | Catalytically dead ADAR1 point-mutation knock-in mice |
| What is the isoform-specific role of ADAR1 p150 versus p110? | Isoform-specific knockout or tagged knock-in cell lines |
| Can ADAR1 editing be redirected to therapeutic targets? | Overexpression of engineered ADAR1 or RNA-guided editors |
| How does loss of ADAR1 affect tumor immunogenicity? | ADAR1 knockout in syngeneic tumor cells followed by immune profiling |
| Does ADAR1 protect against sepsis-induced lung injury? | Macrophage-specific ADAR1 knockout in LPS models |
| What dsRNA substrates are edited in a given cell type? | Knock-in of tagged ADAR1 followed by CLIP-seq or RIP-seq |
How to Study the double-stranded RNA adenosine deaminase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| RNA-seq | Transcriptome-wide A-to-I editing sites | Mapping editing landscapes in knockout versus wild-type cells |
| Ribo-seq | Ribosome occupancy and translation efficiency | Detecting PKR-mediated translational shutdown |
| CLIP-seq | Direct RNA binding sites of ADAR1 | Identifying substrate specificity and isoform differences |
| Proteomics | Protein interaction partners of ADAR1 | Discovering regulators of GO:0003726 activity |
| Immunofluorescence | Subcellular localization of ADAR1 isoforms | Distinguishing p150 and p110 functions |
| Reporter assays | Interferon or NF-kB activation | Measuring innate immune activation upon editing loss |
| CRISPR screens | Genes that modify editing or dsRNA sensing | Identifying synthetic lethal interactions |
| qPCR | Expression of interferon-stimulated genes | Monitoring interferonopathy in models |
RNA sequencing and editing detection
RNA-seq coupled with bioinformatic pipelines can identify A-to-I editing sites transcriptome-wide by comparing genomic and cDNA sequences, revealing the footprint of GO:0003726 activity. This approach is foundational for mapping editing landscapes in health and disease.
Ribo-seq and translational profiling
Ribo-seq measures ribosome occupancy and can detect translational shutdown caused by PKR activation when ADAR1 editing is compromised. It provides a functional readout of the consequences of altered GO:0003726 activity.
Proteomics and interactomics
Affinity purification and mass spectrometry can identify proteins that interact with ADAR1 and modulate its editing activity, helping to dissect the regulatory network of GO:0003726. These methods complement genetic approaches.
Imaging and cellular localization
Fluorescence microscopy of tagged ADAR1 isoforms reveals their nuclear versus cytoplasmic distribution, which determines substrate access and function. Live-cell imaging can track dsRNA accumulation upon loss of editing.
How CRISPR Can Be Used to Study GO:0003726 double-stranded RNA adenosine deaminase activity
Knockout
CRISPR knockout of ADAR or its downstream sensors is widely used to study the consequences of losing GO:0003726 activity, including embryonic lethality, autoinflammation, and tumor immunogenicity. Knockout models help establish causality between editing loss and disease phenotypes.
Point Mutation
Catalytically dead ADAR1 point mutants separate editing-dependent from editing-independent functions, which is crucial because ADAR1 has both activities. Such models have revealed that some immune-suppressive functions of ADAR1 may not require deaminase activity.
Knock-in
Knock-in of epitope tags or fluorescent reporters into the endogenous ADAR locus enables precise tracking of isoform expression and localization without overexpression artifacts. This is valuable for understanding how GO:0003726 is regulated in native contexts.
Overexpression
Overexpression of wild-type or engineered ADAR1, or of RNA-guided RNA editors derived from Cas9 and IscB, allows gain-of-function studies and therapeutic editing applications. These systems can be used to redirect editing to specific transcripts.
How EDITGENE Supports double-stranded RNA adenosine deaminase activity Research
Researchers studying double-stranded RNA adenosine deaminase activity-related genes often need to determine whether a candidate gene is causally involved in editing, immune sensing, or disease phenotypes. EDITGENE provides a comprehensive suite of CRISPR services to accelerate this discovery process.
Contact EDITGENE today to design your custom CRISPR model for double-stranded RNA adenosine deaminase activity research.
Frequently Asked Questions About double-stranded RNA adenosine deaminase activity
What is double-stranded RNA adenosine deaminase activity?
It is the enzyme activity defined by GO:0003726 that converts adenosine to inosine within double-stranded RNA, releasing ammonium.
What genes are involved in double-stranded RNA adenosine deaminase activity?
The primary gene is ADAR, which encodes ADAR1; ADARB1 encodes the related ADAR2 enzyme.
What is the role of ADAR1 in the immune system?
ADAR1 edits endogenous dsRNA to prevent activation of sensors like MDA5 and PKR, thereby avoiding autoinflammation.
What happens when ADAR1 is knocked out?
Knockout of ADAR1 leads to accumulation of unedited dsRNA, activation of innate immune sensors, translational shutdown, and severe autoinflammation or embryonic lethality.
How is A-to-I editing detected?
A-to-I editing is typically detected by RNA-seq followed by bioinformatic comparison of genomic and cDNA sequences to identify A-to-G changes.
Is ADAR1 involved in cancer?
Yes, ADAR1 can mask ZBP1-driven necroptosis and contribute to immunotherapy resistance, making it a potential cancer target.
What is the difference between ADAR1 p150 and p110?
p150 is interferon-inducible and mainly cytoplasmic, protecting against MDA5 activation, while p110 is constitutively expressed and nuclear, protecting against PKR activation.
Can CRISPR be used to study double-stranded RNA adenosine deaminase activity?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models are widely used to dissect ADAR1 functions and editing activity.
What diseases are linked to defects in this activity?
Defects are linked to Aicardi-Goutieres syndrome, interferonopathies, sepsis-induced lung injury, and pain sensitization.
What are RNA-guided RNA editors?
They are engineered enzymes derived from Cas9 or IscB that can be programmed to edit RNA, offering therapeutic potential related to GO:0003726.
Conclusion
GO:0003726, double-stranded RNA adenosine deaminase activity, is a fundamental molecular function that safeguards the transcriptome and immune homeostasis by converting adenosine to inosine in dsRNA. Its dysregulation underlies a spectrum of human diseases, from autoinflammatory interferonopathies to cancer and sepsis. Continued research using CRISPR-based models and advanced RNA profiling will deepen our understanding of this activity and unlock new therapeutic opportunities.
References
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- 4. de Reuver R et al.. 2024. Novel insights into double-stranded RNA-mediated immunopathology.. Nat Rev Immunol 24(4):235-249 PMID: 37752355
- 5. Hu SB et al.. 2023. ADAR1p150 prevents MDA5 and PKR activation via distinct mechanisms to avert fatal autoinflammation.. Mol Cell 83(21):3869-3884.e7 PMID: 37797622
- 6. Zhao X et al.. 2024. ADAR1 protects pulmonary macrophages from sepsis-induced pyroptosis and lung injury through miR-21/A20 signaling.. Int J Biol Sci 20(2):464-485 PMID: 38169584
- 7. Chung H et al.. 2018. Human ADAR1 Prevents Endogenous RNA from Triggering Translational Shutdown.. Cell 172(4):811-824.e14 PMID: 29395325
- 8. Wang B et al.. 2024. Targeting exosomal double-stranded RNA-TLR3 signaling pathway attenuates morphine tolerance and hyperalgesia.. Cell Rep Med 5(10):101782 PMID: 39413734
