-
Frontiers in Immunology 2022Deficiency of Adenosine deaminase 2 (DADA2) is a monogenic autoinflammatory disorder presenting with a broad spectrum of clinical manifestations, including... (Review)
Review
Deficiency of Adenosine deaminase 2 (DADA2) is a monogenic autoinflammatory disorder presenting with a broad spectrum of clinical manifestations, including immunodeficiency, vasculopathy and hematologic disease. Biallelic mutations in ADA2 gene have been associated with a decreased ADA2 activity, leading to reduction in deamination of adenosine and deoxyadenosine into inosine and deoxyinosine and subsequent accumulation of extracellular adenosine. In the early reports, the pivotal role of innate immunity in DADA2 pathogenic mechanism has been underlined, showing a skewed polarization from the M2 macrophage subtype to the proinflammatory M1 subtype, with an increased production of inflammatory cytokines such as TNF-α. Subsequently, a dysregulation of NETosis, triggered by the excess of extracellular Adenosine, has been implicated in the pathogenesis of DADA2. In the last few years, evidence is piling up that adaptive immunity is profoundly altered in DADA2 patients, encompassing both T and B branches, with a disrupted homeostasis in T-cell subsets and a B-cell skewing defect. Type I/type II IFN pathway upregulation has been proposed as a possible core signature in DADA2 T cells and monocytes but also an increased IFN-β secretion directly from endothelial cells has been described. So far, a unifying clear pathophysiological explanation for the coexistence of systemic inflammation, immunedysregulation and hematological defects is lacking. In this review, we will explore thoroughly the latest understanding regarding DADA2 pathophysiological process, with a particular focus on dysregulation of both innate and adaptive immunity and their interacting role in the development of the disease.
Topics: Adaptive Immunity; Adenosine; Adenosine Deaminase; Agammaglobulinemia; Endothelial Cells; Humans; Intercellular Signaling Peptides and Proteins; Polyarteritis Nodosa; Severe Combined Immunodeficiency
PubMed: 35898506
DOI: 10.3389/fimmu.2022.935957 -
Redox Biology Nov 2023Astrocytes affect stroke outcomes by acquiring functionally dominant phenotypes. Understanding molecular mechanisms dictating astrocyte functional status after brain...
Astrocytes affect stroke outcomes by acquiring functionally dominant phenotypes. Understanding molecular mechanisms dictating astrocyte functional status after brain ischemia/reperfusion may reveal new therapeutic strategies. Adenosine deaminase acting on RNA (ADAR1), an RNA editing enzyme, is not normally expressed in astrocytes, but highly induced in astrocytes in ischemic stroke lesions. The expression of ADAR1 steeply increased from day 1 to day 7 after middle cerebral artery occlusion (MCAO) for 1 h followed by reperfusion. ADAR1 deficiency markedly ameliorated the volume of the cerebral infarction and neurological deficits as shown by the rotarod and cylinder tests, which was due to the reduction of the numbers of activated astrocytes and microglia. Surprisingly, ADAR1 was mainly expressed in astrocytes while only marginally in microglia. In primary cultured astrocytes, ADAR1 promoted astrocyte proliferation via phosphatidylinositol 3-kinase (PI3K)/Akt pathway. Furthermore, ADAR1 deficiency inhibited brain cell apoptosis in mice with MCAO as well as in activated astrocyte-conditioned medium-induced neurons in vitro. It appeared that ADAR1 induces neuron apoptosis by secretion of IL-1β, IL-6 and TNF-α from astrocytes through the production of reactive oxygen species. These results indicated that ADAR1 is a novel regulator promoting the proliferation of the activated astrocytes following ischemic stroke, which produce various inflammatory cytokines, leading to neuron apoptosis and worsened ischemic stroke outcome.
Topics: Mice; Animals; Astrocytes; Phosphatidylinositol 3-Kinases; Brain Ischemia; Infarction, Middle Cerebral Artery; Neurons; Brain Injuries; Ischemic Stroke; Apoptosis; Reperfusion Injury; Adenosine Deaminase
PubMed: 37801857
DOI: 10.1016/j.redox.2023.102903 -
Science (New York, N.Y.) Jul 2020CRISPR-Cas-guided base editors convert A•T to G•C, or C•G to T•A, in cellular DNA for precision genome editing. To understand the molecular basis for DNA...
CRISPR-Cas-guided base editors convert A•T to G•C, or C•G to T•A, in cellular DNA for precision genome editing. To understand the molecular basis for DNA adenosine deamination by adenine base editors (ABEs), we determined a 3.2-angstrom resolution cryo-electron microscopy structure of ABE8e in a substrate-bound state in which the deaminase domain engages DNA exposed within the CRISPR-Cas9 R-loop complex. Kinetic and structural data suggest that ABE8e catalyzes DNA deamination up to ~1100-fold faster than earlier ABEs because of mutations that stabilize DNA substrates in a constrained, transfer RNA-like conformation. Furthermore, ABE8e's accelerated DNA deamination suggests a previously unobserved transient DNA melting that may occur during double-stranded DNA surveillance by CRISPR-Cas9. These results explain ABE8e-mediated base-editing outcomes and inform the future design of base editors.
Topics: Adenine; Adenosine Deaminase; CRISPR-Associated Protein 9; CRISPR-Cas Systems; Cryoelectron Microscopy; DNA; Deamination; Escherichia coli Proteins; Gene Editing
PubMed: 32732424
DOI: 10.1126/science.abb1390 -
Nature Biotechnology Sep 2019Base editors use DNA-modifying enzymes targeted with a catalytically impaired CRISPR protein to precisely install point mutations. Here, we develop phage-assisted...
Base editors use DNA-modifying enzymes targeted with a catalytically impaired CRISPR protein to precisely install point mutations. Here, we develop phage-assisted continuous evolution of base editors (BE-PACE) to improve their editing efficiency and target sequence compatibility. We used BE-PACE to evolve cytosine base editors (CBEs) that overcome target sequence context constraints of canonical CBEs. One evolved CBE, evoAPOBEC1-BE4max, is up to 26-fold more efficient at editing cytosine in the GC context, a disfavored context for wild-type APOBEC1 deaminase, while maintaining efficient editing in all other sequence contexts tested. Another evolved deaminase, evoFERNY, is 29% smaller than APOBEC1 and edits efficiently in all tested sequence contexts. We also evolved a CBE based on CDA1 deaminase with much higher editing efficiency at difficult target sites. Finally, we used data from evolved CBEs to illuminate the relationship between deaminase activity, base editing efficiency, editing window width and byproduct formation. These findings establish a system for rapid evolution of base editors and inform their use and improvement.
Topics: Adenosine Deaminase; Animals; Base Sequence; CRISPR-Cas Systems; Cell Line; Directed Molecular Evolution; Gene Editing; Gene Expression Regulation, Enzymologic; Gene Targeting; Humans; INDEL Mutation; Mice
PubMed: 31332326
DOI: 10.1038/s41587-019-0193-0 -
Immunity May 2023Immune cell trafficking constitutes a fundamental component of immunological response to tissue injury, but the contribution of intrinsic RNA nucleotide modifications to...
Immune cell trafficking constitutes a fundamental component of immunological response to tissue injury, but the contribution of intrinsic RNA nucleotide modifications to this response remains elusive. We report that RNA editor ADAR2 exerts a tissue- and stress-specific regulation of endothelial responses to interleukin-6 (IL-6), which tightly controls leukocyte trafficking in IL-6-inflamed and ischemic tissues. Genetic ablation of ADAR2 from vascular endothelial cells diminished myeloid cell rolling and adhesion on vascular walls and reduced immune cell infiltration within ischemic tissues. ADAR2 was required in the endothelium for the expression of the IL-6 receptor subunit, IL-6 signal transducer (IL6ST; gp130), and subsequently, for IL-6 trans-signaling responses. ADAR2-induced adenosine-to-inosine RNA editing suppressed the Drosha-dependent primary microRNA processing, thereby overwriting the default endothelial transcriptional program to safeguard gp130 expression. This work demonstrates a role for ADAR2 epitranscriptional activity as a checkpoint in IL-6 trans-signaling and immune cell trafficking to sites of tissue injury.
Topics: RNA; Interleukin-6; Endothelial Cells; Cytokine Receptor gp130; Endothelium; Adenosine Deaminase
PubMed: 37100060
DOI: 10.1016/j.immuni.2023.03.021 -
Cell Mar 2023Adenosine-to-inosine RNA editing has been proposed to be involved in a bacterial anti-phage defense system called RADAR. RADAR contains an adenosine triphosphatase...
Adenosine-to-inosine RNA editing has been proposed to be involved in a bacterial anti-phage defense system called RADAR. RADAR contains an adenosine triphosphatase (RdrA) and an adenosine deaminase (RdrB). Here, we report cryo-EM structures of RdrA, RdrB, and currently identified RdrA-RdrB complexes in the presence or absence of RNA and ATP. RdrB assembles into a dodecameric cage with catalytic pockets facing outward, while RdrA adopts both autoinhibited tetradecameric and activation-competent heptameric rings. Structural and functional data suggest a model in which RNA is loaded through the bottom section of the RdrA ring and translocated along its inner channel, a process likely coupled with ATP-binding status. Intriguingly, up to twelve RdrA rings can dock one RdrB cage with precise alignments between deaminase catalytic pockets and RNA-translocation channels, indicative of enzymatic coupling of RNA translocation and deamination. Our data uncover an interesting mechanism of enzymatic coupling and anti-phage defense through supramolecular assemblies.
Topics: RNA; Adenosine Triphosphate; Adenosine Deaminase
PubMed: 36764292
DOI: 10.1016/j.cell.2023.01.026 -
Nucleic Acids Research May 2023Adenosine deaminase acting on RNA ADAR1 promotes A-to-I conversion in double-stranded and structured RNAs. ADAR1 has two isoforms transcribed from different promoters:...
Adenosine deaminase acting on RNA ADAR1 promotes A-to-I conversion in double-stranded and structured RNAs. ADAR1 has two isoforms transcribed from different promoters: cytoplasmic ADAR1p150 is interferon-inducible while ADAR1p110 is constitutively expressed and primarily localized in the nucleus. Mutations in ADAR1 cause Aicardi - Goutières syndrome (AGS), a severe autoinflammatory disease associated with aberrant IFN production. In mice, deletion of ADAR1 or the p150 isoform leads to embryonic lethality driven by overexpression of interferon-stimulated genes. This phenotype is rescued by deletion of the cytoplasmic dsRNA-sensor MDA5 indicating that the p150 isoform is indispensable and cannot be rescued by ADAR1p110. Nevertheless, editing sites uniquely targeted by ADAR1p150 remain elusive. Here, by transfection of ADAR1 isoforms into ADAR-less mouse cells we detect isoform-specific editing patterns. Using mutated ADAR variants, we test how intracellular localization and the presence of a Z-DNA binding domain-α affect editing preferences. These data show that ZBDα only minimally contributes to p150 editing-specificity while isoform-specific editing is primarily directed by the intracellular localization of ADAR1 isoforms. Our study is complemented by RIP-seq on human cells ectopically expressing tagged-ADAR1 isoforms. Both datasets reveal enrichment of intronic editing and binding by ADAR1p110 while ADAR1p150 preferentially binds and edits 3'UTRs.
Topics: Animals; Humans; Mice; Adenosine Deaminase; Cell Nucleus; Cytoplasm; Interferons; Protein Isoforms; RNA, Double-Stranded; RNA Editing
PubMed: 37026479
DOI: 10.1093/nar/gkad265 -
Cold Spring Harbor Perspectives in... Mar 2019Long double-stranded RNAs (dsRNAs) are abundantly expressed in animals, in which they frequently occur in introns and 3' untranslated regions of mRNAs. Functions of... (Review)
Review
Long double-stranded RNAs (dsRNAs) are abundantly expressed in animals, in which they frequently occur in introns and 3' untranslated regions of mRNAs. Functions of long, cellular dsRNAs are poorly understood, although deficiencies in adenosine deaminases that act on RNA, or ADARs, promote their recognition as viral dsRNA and an aberrant immune response. Diverse dsRNA-binding proteins bind cellular dsRNAs, hinting at additional roles. Understanding these roles is facilitated by mapping the genomic locations that express dsRNA in various tissues and organisms. ADAR editing provides a signature of dsRNA structure in cellular transcripts. In this review, we detail approaches to map ADAR editing sites and dsRNAs genome-wide, with particular focus on high-throughput sequencing methods and considerations for their successful application to the detection of editing sites and dsRNAs.
Topics: Adenosine Deaminase; Animals; Genetic Techniques; Humans; RNA, Double-Stranded
PubMed: 30824577
DOI: 10.1101/cshperspect.a035352 -
Aging Oct 2022Adenosine deaminase (ADA) is a key enzyme that catalyzes the deamination of adenosine into inosine, which eventually decomposes into uric acid (UA). A body of papers...
BACKGROUND
Adenosine deaminase (ADA) is a key enzyme that catalyzes the deamination of adenosine into inosine, which eventually decomposes into uric acid (UA). A body of papers have reported that adenosine and UA are closely related to cerebrovascular events. However, the association between serum ADA activity and acute cerebral infarction (ACI) remains unclear.
METHODS
7913 subjects were enrolled, including 3968 ACI patients and 3945 controls, in this study. An automatic biochemistry analyzer was used to determine serum activity.
RESULTS
Serum ADA activity was found that was significantly decreased in patients with ACI (10.10 ± 3.72 U/L) compared to those without ACI (11.07 ± 2.85 U/L, < 0.001). After Logistic regression analysis, ADA concentrations were negatively correlated with ACI (OR = 1.161, 95% CI: 1.140-1.183, < 0.001). Smoking and alcohol consumption decreased serum ADA concentrations in patients with ACI, whereas diabetes and hypertension had the opposite effect.
CONCLUSIONS
Serum ADA concentrations in patients with ACI are markedly decreased, suggesting that the decreased ADA concentrations may be involved in the pathogenesis of ACI. We hypothesized that decreased ADA activity may be an adaptive mechanism to maintain adenosine levels and protect against ischemic brain injury.
Topics: Humans; Adenosine Deaminase; Retrospective Studies; Case-Control Studies; Stroke; Brain Ischemia; Adenosine; Cerebral Infarction
PubMed: 36260871
DOI: 10.18632/aging.204338 -
Cell Communication and Signaling : CCS Jan 2024Adenosine-to-inosine (A-to-I) editing of RNA, catalyzed by adenosine deaminase acting on RNA (ADAR) enzymes, is a prevalent RNA modification in mammals. It has been... (Review)
Review
Adenosine-to-inosine (A-to-I) editing of RNA, catalyzed by adenosine deaminase acting on RNA (ADAR) enzymes, is a prevalent RNA modification in mammals. It has been shown that A-to-I editing plays a critical role in multiple diseases, such as cardiovascular disease, neurological disorder, and particularly cancer. ADARs are the family of enzymes, including ADAR1, ADAR2, and ADAR3, that catalyze the occurrence of A-to-I editing. Notably, A-to-I editing is mainly catalyzed by ADAR1. Given the significance of A-to-I editing in disease development, it is important to unravel the complex roles of ADAR1 in cancer for the development of novel therapeutic interventions.In this review, we briefly describe the progress of research on A-to-I editing and ADARs in cancer, mainly focusing on the role of ADAR1 in cancer from both editing-dependent and independent perspectives. In addition, we also summarized the factors affecting the expression and editing activity of ADAR1 in cancer.
Topics: Animals; Humans; RNA-Binding Proteins; Neoplasms; Adenosine Deaminase; RNA; Mammals
PubMed: 38233935
DOI: 10.1186/s12964-023-01465-x