1
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Hu SB, Li JB. RNA editing and immune control: from mechanism to therapy. Curr Opin Genet Dev 2024; 86:102195. [PMID: 38643591 PMCID: PMC11162905 DOI: 10.1016/j.gde.2024.102195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 04/02/2024] [Accepted: 04/02/2024] [Indexed: 04/23/2024]
Abstract
Adenosine-to-inosine RNA editing, catalyzed by the enzymes ADAR1 and ADAR2, stands as a pervasive RNA modification. A primary function of ADAR1-mediated RNA editing lies in labeling endogenous double-stranded RNAs (dsRNAs) as 'self', thereby averting their potential to activate innate immune responses. Recent findings have highlighted additional roles of ADAR1, independent of RNA editing, that are crucial for immune control. Here, we focus on recent progress in understanding ADAR1's RNA editing-dependent and -independent roles in immune control. We describe how ADAR1 regulates various dsRNA innate immune receptors through distinct mechanisms. Furthermore, we discuss the implications of ADAR1 and RNA editing in diseases, including autoimmune diseases and cancers.
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Affiliation(s)
- Shi-Bin Hu
- Department of Genetics, Stanford University, Stanford, CA 94305, USA.
| | - Jin Billy Li
- Department of Genetics, Stanford University, Stanford, CA 94305, USA.
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2
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Dorrity TJ, Shin H, Gertie JA, Chung H. The Sixth Sense: Self-nucleic acid sensing in the brain. Adv Immunol 2024; 161:53-83. [PMID: 38763702 PMCID: PMC11186578 DOI: 10.1016/bs.ai.2024.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2024]
Abstract
Our innate immune system uses pattern recognition receptors (PRRs) as a first line of defense to detect microbial ligands and initiate an immune response. Viral nucleic acids are key ligands for the activation of many PRRs and the induction of downstream inflammatory and antiviral effects. Initially it was thought that endogenous (self) nucleic acids rarely activated these PRRs, however emerging evidence indicates that endogenous nucleic acids are able to activate host PRRs in homeostasis and disease. In fact, many regulatory mechanisms are in place to finely control and regulate sensing of self-nucleic acids by PRRs. Sensing of self-nucleic acids is particularly important in the brain, as perturbations to nucleic acid sensing commonly leads to neuropathology. This review will highlight the role of nucleic acid sensors in the brain, both in disease and homeostasis. We also indicate the source of endogenous stimulatory nucleic acids where known and summarize future directions for the study of this growing field.
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Key Words
- Brain
- DNA sensing PRRs: cGAS, AIM2, TLR9
- Neurodegeneration: Aicardi-Goutieres syndrome (AGS), Alzheimer's disease, Amyotrophic lateral sclerosis, Stroke, Traumatic brain injury
- Neurodevelopment
- Neuroinflammation
- Nuecleic acid immunity
- Pattern recognition receptors (PRRs)
- RNA sensing PRRs: MDA5, RIG-I, PKR, TLR3, TLR7/8
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Affiliation(s)
- Tyler J Dorrity
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, United States
| | - Heegwon Shin
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, United States
| | - Jake A Gertie
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, United States; Integrated Program in Cellular, Molecular, and Biomedical Studies, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, United States; Medical Scientist Training Program, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, United States
| | - Hachung Chung
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, United States.
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3
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Huang Y, Jiang W, Zhou R. DAMP sensing and sterile inflammation: intracellular, intercellular and inter-organ pathways. Nat Rev Immunol 2024:10.1038/s41577-024-01027-3. [PMID: 38684933 DOI: 10.1038/s41577-024-01027-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/20/2024] [Indexed: 05/02/2024]
Abstract
Damage-associated molecular patterns (DAMPs) are endogenous molecules that are released from host cells as a result of cell death or damage. The release of DAMPs in tissues is associated with loss of tissue homeostasis. Sensing of DAMPs by innate immune receptors triggers inflammation, which can be beneficial in initiating the processes that restore tissue homeostasis but can also drive inflammatory diseases. In recent years, the sensing of intracellular DAMPs has received extensive attention in the field of sterile inflammation. However, emerging studies have shown that DAMPs that originate from neighbouring cells, and even from distal tissues or organs, also mediate sterile inflammatory responses. This multi-level sensing of DAMPs is crucial for intercellular, trans-tissue and trans-organ communication. Here, we summarize how DAMP-sensing receptors detect DAMPs from intracellular, intercellular or distal tissue and organ sources to mediate sterile inflammation. We also discuss the possibility of targeting DAMPs or their corresponding receptors to treat inflammatory diseases.
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Affiliation(s)
- Yi Huang
- Key Laboratory of Immune Response and Immunotherapy, Institute of Health and Medicine, Hefei Comprehensive National Science Center, Hefei, China
| | - Wei Jiang
- Key Laboratory of Immune Response and Immunotherapy, School of Basic Medical Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China.
| | - Rongbin Zhou
- Key Laboratory of Immune Response and Immunotherapy, Institute of Health and Medicine, Hefei Comprehensive National Science Center, Hefei, China.
- Key Laboratory of Immune Response and Immunotherapy, School of Basic Medical Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China.
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4
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Jarmoskaite I, Li JB. Multifaceted roles of RNA editing enzyme ADAR1 in innate immunity. RNA (NEW YORK, N.Y.) 2024; 30:500-511. [PMID: 38531645 PMCID: PMC11019752 DOI: 10.1261/rna.079953.124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 02/09/2024] [Indexed: 03/28/2024]
Abstract
Innate immunity must be tightly regulated to enable sensitive pathogen detection while averting autoimmunity triggered by pathogen-like host molecules. A hallmark of viral infection, double-stranded RNAs (dsRNAs) are also abundantly encoded in mammalian genomes, necessitating surveillance mechanisms to distinguish "self" from "nonself." ADAR1, an RNA editing enzyme, has emerged as an essential safeguard against dsRNA-induced autoimmunity. By converting adenosines to inosines (A-to-I) in long dsRNAs, ADAR1 covalently marks endogenous dsRNAs, thereby blocking the activation of the cytoplasmic dsRNA sensor MDA5. Moreover, beyond its editing function, ADAR1 binding to dsRNA impedes the activation of innate immune sensors PKR and ZBP1. Recent landmark studies underscore the utility of silencing ADAR1 for cancer immunotherapy, by exploiting the ADAR1-dependence developed by certain tumors to unleash an antitumor immune response. In this perspective, we summarize the genetic and mechanistic evidence for ADAR1's multipronged role in suppressing dsRNA-mediated autoimmunity and explore the evolving roles of ADAR1 as an immuno-oncology target.
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Affiliation(s)
- Inga Jarmoskaite
- Department of Genetics, Stanford University, Stanford, California 94305, USA
- AIRNA Corporation, Cambridge, Massachusetts 02142, USA
| | - Jin Billy Li
- Department of Genetics, Stanford University, Stanford, California 94305, USA
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5
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Ma M, Jiang W, Zhou R. DAMPs and DAMP-sensing receptors in inflammation and diseases. Immunity 2024; 57:752-771. [PMID: 38599169 DOI: 10.1016/j.immuni.2024.03.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 02/17/2024] [Accepted: 03/01/2024] [Indexed: 04/12/2024]
Abstract
Damage-associated molecular patterns (DAMPs) are endogenous danger molecules produced in cellular damage or stress, and they can activate the innate immune system. DAMPs contain multiple types of molecules, including nucleic acids, proteins, ions, glycans, and metabolites. Although these endogenous molecules do not trigger immune response under steady-state condition, they may undergo changes in distribution, physical or chemical property, or concentration upon cellular damage or stress, and then they become DAMPs that can be sensed by innate immune receptors to induce inflammatory response. Thus, DAMPs play an important role in inflammation and inflammatory diseases. In this review, we summarize the conversion of homeostatic molecules into DAMPs; the diverse nature and classification, cellular origin, and sensing of DAMPs; and their role in inflammation and related diseases. Furthermore, we discuss the clinical strategies to treat DAMP-associated diseases via targeting DAMP-sensing receptors.
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Affiliation(s)
- Ming Ma
- Key Laboratory of Immune Response and Immunotherapy, Center for Advanced Interdisciplinary Science and Biomedicine of IHM, School of Basic Medical Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, Anhui, China
| | - Wei Jiang
- Key Laboratory of Immune Response and Immunotherapy, Center for Advanced Interdisciplinary Science and Biomedicine of IHM, School of Basic Medical Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, Anhui, China
| | - Rongbin Zhou
- Key Laboratory of Immune Response and Immunotherapy, Center for Advanced Interdisciplinary Science and Biomedicine of IHM, School of Basic Medical Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, Anhui, China; Department of Geriatrics, Gerontology Institute of Anhui Province, The First Affiliated Hospital of University of Science and Technology of China, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230001, China.
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6
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Pan Y, Kang X. Limited dsRNA editing impedes leukemia stem cells. Trends Cancer 2024; 10:280-282. [PMID: 38458943 PMCID: PMC11047023 DOI: 10.1016/j.trecan.2024.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Accepted: 02/26/2024] [Indexed: 03/10/2024]
Abstract
Understanding the mechanisms underlying the generation and maintenance of leukemia stem cells (LSCs) is crucial for the development of effective therapies against T cell acute lymphoblastic leukemia (T-ALL). In a recent study, Rivera et al. discovered that elevated adenosine deaminase acting on RNA (ADAR)-1-mediated RNA editing is a distinguishing feature of T-ALL relapse, and that ADAR1 suppresses apoptosis triggered by the double-stranded (ds)RNA-sensing pathway.
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Affiliation(s)
- Yi Pan
- Division of Hematology and Oncology, Center for Precision Medicine, Department of Medicine, University of Missouri School of Medicine, Columbia, MO 65212, USA
| | - XunLei Kang
- Division of Hematology and Oncology, Center for Precision Medicine, Department of Medicine, University of Missouri School of Medicine, Columbia, MO 65212, USA; Ellis Fischel Cancer Center at MU Health Care, University of Missouri, Columbia, MO 65212, USA.
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7
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de Reuver R, Maelfait J. Novel insights into double-stranded RNA-mediated immunopathology. Nat Rev Immunol 2024; 24:235-249. [PMID: 37752355 DOI: 10.1038/s41577-023-00940-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2023] [Indexed: 09/28/2023]
Abstract
Recent progress in human and mouse genetics has transformed our understanding of the molecular mechanisms by which recognition of self double-stranded RNA (self-dsRNA) causes immunopathology. Novel mouse models recapitulate loss-of-function mutations in the RNA editing enzyme ADAR1 that are found in patients with Aicardi-Goutières syndrome (AGS) - a monogenic inflammatory disease associated with increased levels of type I interferon. Extensive analyses of the genotype-phenotype relationships in these mice have now firmly established a causal relationship between increased intracellular concentrations of endogenous immunostimulatory dsRNA and type I interferon-driven immunopathology. Activation of the dsRNA-specific immune sensor MDA5 perpetuates the overproduction of type I interferons, and chronic engagement of the interferon-inducible innate immune receptors PKR and ZBP1 by dsRNA drives immunopathology by activating an integrated stress response or by inducing excessive cell death. Biochemical and genetic data support a role for the p150 isoform of ADAR1 in the cytosol in suppressing the spontaneous, pathological response to self-dsRNA.
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Affiliation(s)
- Richard de Reuver
- VIB-UGent Center for Inflammation Research, Ghent, Belgium
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Jonathan Maelfait
- VIB-UGent Center for Inflammation Research, Ghent, Belgium.
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium.
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8
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Yang K, Jeltema D, Yan N. Innate immune sensing of macromolecule homeostasis. Adv Immunol 2024; 161:17-51. [PMID: 38763701 DOI: 10.1016/bs.ai.2024.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2024]
Abstract
The innate immune system uses a distinct set of germline-encoded pattern recognition receptors to recognize molecular patterns initially thought to be unique to microbial invaders, named pathogen-associated molecular patterns. The concept was later further developed to include similar molecular patterns originating from host cells during tissue damage, known as damage-associated molecular patterns. However, recent advances in the mechanism of monogenic inflammatory diseases have highlighted a much more expansive repertoire of cellular functions that are monitored by innate immunity. Here, we summarize several examples in which an innate immune response is triggered when homeostasis of macromolecule in the cell is disrupted in non-infectious or sterile settings. These ever-growing sensing mechanisms expand the repertoire of innate immune recognition, positioning it not only as a key player in host defense but also as a gatekeeper of cellular homeostasis. Therapeutics inspired by these advances to restore cellular homeostasis and correct the immune system could have far-reaching implications.
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Affiliation(s)
- Kun Yang
- Department of Immunology, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Devon Jeltema
- Department of Immunology, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Nan Yan
- Department of Immunology, University of Texas Southwestern Medical Center, Dallas, TX, United States.
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9
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Zhang D, Zhu L, Gao Y, Wang Y, Li P. RNA editing enzymes: structure, biological functions and applications. Cell Biosci 2024; 14:34. [PMID: 38493171 PMCID: PMC10944622 DOI: 10.1186/s13578-024-01216-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2023] [Accepted: 03/06/2024] [Indexed: 03/18/2024] Open
Abstract
With the advancement of sequencing technologies and bioinformatics, over than 170 different RNA modifications have been identified. However, only a few of these modifications can lead to base pair changes, which are called RNA editing. RNA editing is a ubiquitous modification in mammalian transcriptomes and is an important co/posttranscriptional modification that plays a crucial role in various cellular processes. There are two main types of RNA editing events: adenosine to inosine (A-to-I) editing, catalyzed by ADARs on double-stranded RNA or ADATs on tRNA, and cytosine to uridine (C-to-U) editing catalyzed by APOBECs. This article provides an overview of the structure, function, and applications of RNA editing enzymes. We discuss the structural characteristics of three RNA editing enzyme families and their catalytic mechanisms in RNA editing. We also explain the biological role of RNA editing, particularly in innate immunity, cancer biogenesis, and antiviral activity. Additionally, this article describes RNA editing tools for manipulating RNA to correct disease-causing mutations, as well as the potential applications of RNA editing enzymes in the field of biotechnology and therapy.
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Affiliation(s)
- Dejiu Zhang
- Institute for Translational Medicine, College of Medicine, The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao, China.
| | - Lei Zhu
- College of Basic Medical, Qingdao Binhai University, Qingdao, China
| | - Yanyan Gao
- Institute for Translational Medicine, College of Medicine, The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao, China
| | - Yin Wang
- Institute for Translational Medicine, College of Medicine, The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao, China
| | - Peifeng Li
- Institute for Translational Medicine, College of Medicine, The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao, China.
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10
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Luca D, Lee S, Hirota K, Okabe Y, Uehori J, Izawa K, Lanz AL, Schütte V, Sivri B, Tsukamoto Y, Hauck F, Behrendt R, Roers A, Fujita T, Nishikomori R, Lee-Kirsch MA, Kato H. Aberrant RNA sensing in regulatory T cells causes systemic autoimmunity. SCIENCE ADVANCES 2024; 10:eadk0820. [PMID: 38427731 PMCID: PMC10906915 DOI: 10.1126/sciadv.adk0820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 01/29/2024] [Indexed: 03/03/2024]
Abstract
Chronic and aberrant nucleic acid sensing causes type I IFN-driven autoimmune diseases, designated type I interferonopathies. We found a significant reduction of regulatory T cells (Tregs) in patients with type I interferonopathies caused by mutations in ADAR1 or IFIH1 (encoding MDA5). We analyzed the underlying mechanisms using murine models and found that Treg-specific deletion of Adar1 caused peripheral Treg loss and scurfy-like lethal autoimmune disorders. Similarly, knock-in mice with Treg-specific expression of an MDA5 gain-of-function mutant caused apoptosis of peripheral Tregs and severe autoimmunity. Moreover, the impact of ADAR1 deficiency on Tregs is multifaceted, involving both MDA5 and PKR sensing. Together, our results highlight the dysregulation of Treg homeostasis by intrinsic aberrant RNA sensing as a potential determinant for type I interferonopathies.
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Affiliation(s)
- Domnica Luca
- Institute of Cardiovascular Immunology, Medical Faculty, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Sumin Lee
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
- Laboratory of Regulatory Information, Institute for Life and Medical Sciences, Kyoto University, Kyoto, Japan
| | - Keiji Hirota
- Institute of Cardiovascular Immunology, Medical Faculty, University Hospital Bonn, University of Bonn, Bonn, Germany
- Laboratory of Integrative Biological Science, Institute for Life and Medical Sciences, Kyoto University, Kyoto, Japan
| | - Yasutaka Okabe
- Laboratory of Immune Homeostasis, WPI Immunology Frontier Research Center, Osaka University, Osaka, Japan
- Center for Infectious Disease Education and Research, Osaka University, Osaka, Japan
| | - Junji Uehori
- Laboratory of Immunology, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, Japan
| | - Kazushi Izawa
- Department of Pediatrics, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Anna-Lisa Lanz
- Division of Pediatric Immunology and Rheumatology, Department of Pediatrics, Dr. von Hauner Children's Hospital, University Hospital, Ludwig-Maximilians-Universität München, Munich, Germany
- Munich Centre for Rare Diseases (M-ZSE), University Hospital, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Verena Schütte
- Institute of Cardiovascular Immunology, Medical Faculty, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Burcu Sivri
- Institute of Cardiovascular Immunology, Medical Faculty, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Yuta Tsukamoto
- Institute of Cardiovascular Immunology, Medical Faculty, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Fabian Hauck
- Division of Pediatric Immunology and Rheumatology, Department of Pediatrics, Dr. von Hauner Children's Hospital, University Hospital, Ludwig-Maximilians-Universität München, Munich, Germany
- Munich Centre for Rare Diseases (M-ZSE), University Hospital, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Rayk Behrendt
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Bonn, Germany
| | - Axel Roers
- Institute of Immunology, University of Heidelberg, Heidelberg, Germany
| | - Takashi Fujita
- Institute of Cardiovascular Immunology, Medical Faculty, University Hospital Bonn, University of Bonn, Bonn, Germany
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
- Laboratory of Regulatory Information, Institute for Life and Medical Sciences, Kyoto University, Kyoto, Japan
| | - Ryuta Nishikomori
- Department of Pediatrics and Child Health, Kurume University School of Medicine, Kurume, Japan
| | - Min Ae Lee-Kirsch
- Department of Pediatrics, University Hospital Carl Gustav Carus and Medical Faculty, Technische Universität Dresden, Dresden, Germany
- University Center for Rare Diseases, University Hospital Carl Gustav Carus and Medical Faculty, Technische Universität Dresden, Dresden, Germany
| | - Hiroki Kato
- Institute of Cardiovascular Immunology, Medical Faculty, University Hospital Bonn, University of Bonn, Bonn, Germany
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11
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Rivera M, Zhang H, Pham J, Isquith J, Zhou QJ, Balaian L, Sasik R, Enlund S, Mark A, Ma W, Holm F, Fisch KM, Kuo DJ, Jamieson C, Jiang Q. Malignant A-to-I RNA editing by ADAR1 drives T cell acute lymphoblastic leukemia relapse via attenuating dsRNA sensing. Cell Rep 2024; 43:113704. [PMID: 38265938 PMCID: PMC10962356 DOI: 10.1016/j.celrep.2024.113704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 10/24/2023] [Accepted: 01/09/2024] [Indexed: 01/26/2024] Open
Abstract
Leukemia-initiating cells (LICs) are regarded as the origin of leukemia relapse and therapeutic resistance. Identifying direct stemness determinants that fuel LIC self-renewal is critical for developing targeted approaches. Here, we show that the RNA-editing enzyme ADAR1 is a crucial stemness factor that promotes LIC self-renewal by attenuating aberrant double-stranded RNA (dsRNA) sensing. Elevated adenosine-to-inosine editing is a common attribute of relapsed T cell acute lymphoblastic leukemia (T-ALL) regardless of molecular subtype. Consequently, knockdown of ADAR1 severely inhibits LIC self-renewal capacity and prolongs survival in T-ALL patient-derived xenograft models. Mechanistically, ADAR1 directs hyper-editing of immunogenic dsRNA to avoid detection by the innate immune sensor melanoma differentiation-associated protein 5 (MDA5). Moreover, we uncover that the cell-intrinsic level of MDA5 dictates the dependency on the ADAR1-MDA5 axis in T-ALL. Collectively, our results show that ADAR1 functions as a self-renewal factor that limits the sensing of endogenous dsRNA. Thus, targeting ADAR1 presents an effective therapeutic strategy for eliminating T-ALL LICs.
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Affiliation(s)
- Maria Rivera
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Moores Cancer Center, La Jolla, CA 92037, USA
| | - Haoran Zhang
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Moores Cancer Center, La Jolla, CA 92037, USA
| | - Jessica Pham
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Jane Isquith
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Qingchen Jenny Zhou
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Moores Cancer Center, La Jolla, CA 92037, USA
| | - Larisa Balaian
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Roman Sasik
- Center for Computational Biology & Bioinformatics (CCBB), University of California, San Diego, La Jolla, CA 92093-0681, USA
| | - Sabina Enlund
- Department of Women's and Children's Health, Division of Pediatric Oncology and Pediatric Surgery, Karolinska Institutet, Solna, Sweden
| | - Adam Mark
- Center for Computational Biology & Bioinformatics (CCBB), University of California, San Diego, La Jolla, CA 92093-0681, USA
| | - Wenxue Ma
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Frida Holm
- Department of Women's and Children's Health, Division of Pediatric Oncology and Pediatric Surgery, Karolinska Institutet, Solna, Sweden
| | - Kathleen M Fisch
- Center for Computational Biology & Bioinformatics (CCBB), University of California, San Diego, La Jolla, CA 92093-0681, USA; Department of Obstetrics, Gynecology & Reproductive Sciences, University of California, San Diego, La Jolla, CA 92037, USA
| | - Dennis John Kuo
- Moores Cancer Center, La Jolla, CA 92037, USA; Division of Pediatric Hematology-Oncology, Rady Children's Hospital San Diego, University of California, San Diego, San Diego, CA 92123, USA
| | - Catriona Jamieson
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Moores Cancer Center, La Jolla, CA 92037, USA
| | - Qingfei Jiang
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Moores Cancer Center, La Jolla, CA 92037, USA.
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12
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Zhang R, Karijolich J. RNA recognition by PKR during DNA virus infection. J Med Virol 2024; 96:e29424. [PMID: 38285432 PMCID: PMC10832991 DOI: 10.1002/jmv.29424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Revised: 01/10/2024] [Accepted: 01/11/2024] [Indexed: 01/30/2024]
Abstract
Protein kinase R (PKR) is a double-stranded RNA (dsRNA) binding protein that plays a crucial role in innate immunity during viral infection and can restrict both DNA and RNA viruses. The potency of its antiviral function is further reflected by the large number of viral-encoded PKR antagonists. However, much about the regulation of dsRNA accumulation and PKR activation during viral infection remains unknown. Since DNA viruses do not have an RNA genome or RNA replication intermediates like RNA viruses do, PKR-mediated dsRNA detection in the context of DNA virus infection is particularly intriguing. Here, we review the current state of knowledge regarding the regulation of PKR activation and its antagonism during infection with DNA viruses.
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Affiliation(s)
- Ruilin Zhang
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232-2363, USA
- Vanderbilt Institute for Infection, Immunology and Inflammation, Vanderbilt Center for Immunobiology, Nashville. Nashville, TN 37232-2363, USA
| | - John Karijolich
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232-2363, USA
- Vanderbilt Institute for Infection, Immunology and Inflammation, Vanderbilt Center for Immunobiology, Nashville. Nashville, TN 37232-2363, USA
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13
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Asundi J, Zhang C, Donnelly‐Roberts D, Solorio JZ, Challagundla M, Connelly C, Boch C, Chen J, Richter M, Maneshi MM, Swensen AM, Lebon L, Schiffmann R, Sanyal S, Sidrauski C, Kolumam G, Baruch A. GDF15 is a dynamic biomarker of the integrated stress response in the central nervous system. CNS Neurosci Ther 2024; 30:e14600. [PMID: 38357857 PMCID: PMC10867791 DOI: 10.1111/cns.14600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 12/11/2023] [Accepted: 12/28/2023] [Indexed: 02/16/2024] Open
Abstract
AIM Characterize Growth Differentiation Factor 15 (GDF15) as a secreted biomarker of the integrated stress response (ISR) within the central nervous system (CNS). METHODS We determined GDF15 levels utilizing in vitro and in vivo neuronal systems wherein the ISR was activated. Primarily, we used the murine model of vanishing white matter disease (VWMD), a neurological disease driven by persistent ISR in the CNS, to establish a link between levels of GDF15 in the cerebrospinal fluid (CSF) and ISR gene expression signature in the CNS. GDF15 was also determined in the CSF of VWM patients. RESULTS GDF15 expression was increased concomitant to ISR activation in stress-induced primary astrocytes as well as in retinal ganglion cells following optic nerve crush, while treatment with 2Bact, a specific eIF2B activator, suppressed both the ISR and GDF15. In the VWMD model, CSF GDF15 levels corresponded with the magnitude of the ISR and were reduced by 2BAct. In VWM patients, mean CSF GDF15 was elevated >20-fold as compared to healthy controls, whereas plasma GDF15 was undifferentiated. CONCLUSIONS These data suggest that CSF GDF15 is a dynamic marker of ISR activation in the CNS and may serve as a pharmacodynamic biomarker for ISR-modulating therapies.
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Affiliation(s)
- Jyoti Asundi
- Calico Life Sciences LLCSouth San FranciscoCaliforniaUSA
| | - Chunlian Zhang
- Calico Life Sciences LLCSouth San FranciscoCaliforniaUSA
| | | | | | | | | | | | | | | | | | | | - Lauren Lebon
- Calico Life Sciences LLCSouth San FranciscoCaliforniaUSA
| | | | | | | | - Ganesh Kolumam
- Calico Life Sciences LLCSouth San FranciscoCaliforniaUSA
| | - Amos Baruch
- Calico Life Sciences LLCSouth San FranciscoCaliforniaUSA
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14
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Cottrell KA, Andrews RJ, Bass BL. The competitive landscape of the dsRNA world. Mol Cell 2024; 84:107-119. [PMID: 38118451 PMCID: PMC10843539 DOI: 10.1016/j.molcel.2023.11.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 11/20/2023] [Accepted: 11/22/2023] [Indexed: 12/22/2023]
Abstract
The ability to sense and respond to infection is essential for life. Viral infection produces double-stranded RNAs (dsRNAs) that are sensed by proteins that recognize the structure of dsRNA. This structure-based recognition of viral dsRNA allows dsRNA sensors to recognize infection by many viruses, but it comes at a cost-the dsRNA sensors cannot always distinguish between "self" and "nonself" dsRNAs. "Self" RNAs often contain dsRNA regions, and not surprisingly, mechanisms have evolved to prevent aberrant activation of dsRNA sensors by "self" RNA. Here, we review current knowledge about the life of endogenous dsRNAs in mammals-the biosynthesis and processing of dsRNAs, the proteins they encounter, and their ultimate degradation. We highlight mechanisms that evolved to prevent aberrant dsRNA sensor activation and the importance of competition in the regulation of dsRNA sensors and other dsRNA-binding proteins.
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Affiliation(s)
- Kyle A Cottrell
- Department of Biochemistry, Purdue University, West Lafayette, IN, USA.
| | - Ryan J Andrews
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Brenda L Bass
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA.
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15
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Hu SB, Heraud-Farlow J, Sun T, Liang Z, Goradia A, Taylor S, Walkley CR, Li JB. ADAR1p150 prevents MDA5 and PKR activation via distinct mechanisms to avert fatal autoinflammation. Mol Cell 2023; 83:3869-3884.e7. [PMID: 37797622 DOI: 10.1016/j.molcel.2023.09.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 07/14/2023] [Accepted: 09/12/2023] [Indexed: 10/07/2023]
Abstract
Effective immunity requires the innate immune system to distinguish foreign nucleic acids from cellular ones. Cellular double-stranded RNAs (dsRNAs) are edited by the RNA-editing enzyme ADAR1 to evade being recognized as viral dsRNA by cytoplasmic dsRNA sensors, including MDA5 and PKR. The loss of ADAR1-mediated RNA editing of cellular dsRNA activates MDA5. Additional RNA-editing-independent functions of ADAR1 have been proposed, but a specific mechanism has not been delineated. We now demonstrate that the loss of ADAR1-mediated RNA editing specifically activates MDA5, whereas loss of the cytoplasmic ADAR1p150 isoform or its dsRNA-binding activity enabled PKR activation. Deleting both MDA5 and PKR resulted in complete rescue of the embryonic lethality of Adar1p150-/- mice to adulthood, contrasting with the limited or no rescue by removing MDA5 or PKR alone. Our findings demonstrate that MDA5 and PKR are the primary in vivo effectors of fatal autoinflammation following the loss of ADAR1p150.
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Affiliation(s)
- Shi-Bin Hu
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Jacki Heraud-Farlow
- St. Vincent's Institute of Medical Research, Fitzroy, VIC 3065, Australia; Department of Medicine, Eastern Hill Precinct, Melbourne Medical School, University of Melbourne, Fitzroy, VIC 3065, Australia
| | - Tao Sun
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Zhen Liang
- St. Vincent's Institute of Medical Research, Fitzroy, VIC 3065, Australia; Department of Medicine, Eastern Hill Precinct, Melbourne Medical School, University of Melbourne, Fitzroy, VIC 3065, Australia
| | - Ankita Goradia
- St. Vincent's Institute of Medical Research, Fitzroy, VIC 3065, Australia
| | - Scott Taylor
- St. Vincent's Institute of Medical Research, Fitzroy, VIC 3065, Australia
| | - Carl R Walkley
- St. Vincent's Institute of Medical Research, Fitzroy, VIC 3065, Australia; Department of Medicine, Eastern Hill Precinct, Melbourne Medical School, University of Melbourne, Fitzroy, VIC 3065, Australia.
| | - Jin Billy Li
- Department of Genetics, Stanford University, Stanford, CA 94305, USA.
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16
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Pfeiffer LS, Stafforst T. Precision RNA base editing with engineered and endogenous effectors. Nat Biotechnol 2023; 41:1526-1542. [PMID: 37735261 DOI: 10.1038/s41587-023-01927-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 07/26/2023] [Indexed: 09/23/2023]
Abstract
RNA base editing refers to the rewriting of genetic information within an intact RNA molecule and serves various functions, such as evasion of the endogenous immune system and regulation of protein function. To achieve this, certain enzymes have been discovered in human cells that catalyze the conversion of one nucleobase into another. This natural process could be exploited to manipulate and recode any base in a target transcript. In contrast to DNA base editing, analogous changes introduced in RNA are not permanent or inheritable but rather allow reversible and doseable effects that appeal to various therapeutic applications. The current practice of RNA base editing involves the deamination of adenosines and cytidines, which are converted to inosines and uridines, respectively. In this Review, we summarize current site-directed RNA base-editing strategies and highlight recent achievements to improve editing efficiency, precision, codon-targeting scope and in vivo delivery into disease-relevant tissues. Besides engineered editing effectors, we focus on strategies to harness endogenous adenosine deaminases acting on RNA (ADAR) enzymes and discuss limitations and future perspectives to apply the tools in basic research and as a therapeutic modality. We expect the field to realize the first RNA base-editing drug soon, likely on a well-defined genetic disease. However, the long-term challenge will be to carve out the sweet spot of the technology where its unique ability is exploited to modulate signaling cues, metabolism or other clinically relevant processes in a safe and doseable manner.
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Affiliation(s)
- Laura S Pfeiffer
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Thorsten Stafforst
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany.
- Gene and RNA Therapy Center, Faculty of Medicine, University of Tübingen, Tübingen, Germany.
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17
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Dorrity TJ, Shin H, Wiegand KA, Aruda J, Closser M, Jung E, Gertie JA, Leone A, Polfer R, Culbertson B, Yu L, Wu C, Ito T, Huang Y, Steckelberg AL, Wichterle H, Chung H. Long 3'UTRs predispose neurons to inflammation by promoting immunostimulatory double-stranded RNA formation. Sci Immunol 2023; 8:eadg2979. [PMID: 37862432 PMCID: PMC11056275 DOI: 10.1126/sciimmunol.adg2979] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 08/18/2023] [Indexed: 10/22/2023]
Abstract
Loss of RNA homeostasis underlies numerous neurodegenerative and neuroinflammatory diseases. However, the molecular mechanisms that trigger neuroinflammation are poorly understood. Viral double-stranded RNA (dsRNA) triggers innate immune responses when sensed by host pattern recognition receptors (PRRs) present in all cell types. Here, we report that human neurons intrinsically carry exceptionally high levels of immunostimulatory dsRNAs and identify long 3'UTRs as giving rise to neuronal dsRNA structures. We found that the neuron-enriched ELAVL family of genes (ELAVL2, ELAVL3, and ELAVL4) can increase (i) 3'UTR length, (ii) dsRNA load, and (iii) activation of dsRNA-sensing PRRs such as MDA5, PKR, and TLR3. In wild-type neurons, neuronal dsRNAs signaled through PRRs to induce tonic production of the antiviral type I interferon. Depleting ELAVL2 in WT neurons led to global shortening of 3'UTR length, reduced immunostimulatory dsRNA levels, and rendered WT neurons susceptible to herpes simplex virus and Zika virus infection. Neurons deficient in ADAR1, a dsRNA-editing enzyme mutated in the neuroinflammatory disorder Aicardi-Goutières syndrome, exhibited intolerably high levels of dsRNA that triggered PRR-mediated toxic inflammation and neuronal death. Depleting ELAVL2 in ADAR1 knockout neurons led to prolonged neuron survival by reducing immunostimulatory dsRNA levels. In summary, neurons are specialized cells where PRRs constantly sense "self" dsRNAs to preemptively induce protective antiviral immunity, but maintaining RNA homeostasis is paramount to prevent pathological neuroinflammation.
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Affiliation(s)
- Tyler J. Dorrity
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, USA
| | - Heegwon Shin
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, USA
| | - Kenenni A. Wiegand
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, USA
| | - Justin Aruda
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, USA
| | - Michael Closser
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, USA
- Department of Neuroscience and Neurology, Columbia University Irving Medical Center, New York, NY, USA
- Center for Motor Neuron Biology and Disease, Columbia University Irving Medical Center, New York, NY, USA
| | - Emily Jung
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, USA
| | - Jake A. Gertie
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, USA
- Integrated Program in Cellular, Molecular, and Biomedical Studies, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
- Medical Scientist Training Program, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Amanda Leone
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, USA
| | - Rachel Polfer
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, USA
| | - Bruce Culbertson
- Integrated Program in Cellular, Molecular, and Biomedical Studies, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
- Medical Scientist Training Program, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Lisa Yu
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, USA
| | - Christine Wu
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, USA
| | - Takamasa Ito
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, USA
| | - Yuefeng Huang
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, USA
| | - Anna-Lena Steckelberg
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Hynek Wichterle
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, USA
- Department of Neuroscience and Neurology, Columbia University Irving Medical Center, New York, NY, USA
- Center for Motor Neuron Biology and Disease, Columbia University Irving Medical Center, New York, NY, USA
| | - Hachung Chung
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, USA
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18
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Datta R, Adamska JZ, Bhate A, Li JB. A-to-I RNA editing by ADAR and its therapeutic applications: From viral infections to cancer immunotherapy. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 15:e1817. [PMID: 37718249 PMCID: PMC10947335 DOI: 10.1002/wrna.1817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Revised: 08/29/2023] [Accepted: 08/29/2023] [Indexed: 09/19/2023]
Abstract
ADAR deaminases catalyze adenosine-to-inosine (A-to-I) editing on double-stranded RNA (dsRNA) substrates that regulate an umbrella of biological processes. One of the two catalytically active ADAR enzymes, ADAR1, plays a major role in innate immune responses by suppression of RNA sensing pathways which are orchestrated through the ADAR1-dsRNA-MDA5 axis. Unedited immunogenic dsRNA substrates are potent ligands for the cellular sensor MDA5. Upon activation, MDA5 leads to the induction of interferons and expression of hundreds of interferon-stimulated genes with potent antiviral activity. In this way, ADAR1 acts as a gatekeeper of the RNA sensing pathway by striking a fine balance between innate antiviral responses and prevention of autoimmunity. Reduced editing of immunogenic dsRNA by ADAR1 is strongly linked to the development of common autoimmune and inflammatory diseases. In viral infections, ADAR1 exhibits both antiviral and proviral effects. This is modulated by both editing-dependent and editing-independent functions, such as PKR antagonism. Several A-to-I RNA editing events have been identified in viruses, including in the insidious viral pathogen, SARS-CoV-2 which regulates viral fitness and infectivity, and could play a role in shaping viral evolution. Furthermore, ADAR1 is an attractive target for immuno-oncology therapy. Overexpression of ADAR1 and increased dsRNA editing have been observed in several human cancers. Silencing ADAR1, especially in cancers that are refractory to immune checkpoint inhibitors, is a promising therapeutic strategy for cancer immunotherapy in conjunction with epigenetic therapy. The mechanistic understanding of dsRNA editing by ADAR1 and dsRNA sensing by MDA5 and PKR holds great potential for therapeutic applications. This article is categorized under: RNA Processing > RNA Editing and Modification RNA in Disease and Development > RNA in Disease.
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Affiliation(s)
- Rohini Datta
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Julia Z Adamska
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Amruta Bhate
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Jin Billy Li
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
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19
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Zhong Y, Zhong X, Qiao L, Wu H, Liu C, Zhang T. Zα domain proteins mediate the immune response. Front Immunol 2023; 14:1241694. [PMID: 37771585 PMCID: PMC10523160 DOI: 10.3389/fimmu.2023.1241694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Accepted: 08/23/2023] [Indexed: 09/30/2023] Open
Abstract
The Zα domain has a compact α/β architecture containing a three-helix bundle flanked on one side by a twisted antiparallel β sheet. This domain displays a specific affinity for double-stranded nucleic acids that adopt a left-handed helical conformation. Currently, only three Zα-domain proteins have been identified in eukaryotes, specifically ADAR1, ZBP1, and PKZ. ADAR1 is a double-stranded RNA (dsRNA) binding protein that catalyzes the conversion of adenosine residues to inosine, resulting in changes in RNA structure, function, and expression. In addition to its editing function, ADAR1 has been shown to play a role in antiviral defense, gene regulation, and cellular differentiation. Dysregulation of ADAR1 expression and activity has been associated with various disease states, including cancer, autoimmune disorders, and neurological disorders. As a sensing molecule, ZBP1 exhibits the ability to recognize nucleic acids with a left-handed conformation. ZBP1 harbors a RIP homotypic interaction motif (RHIM), composed of a highly charged surface region and a leucine-rich hydrophobic core, enabling the formation of homotypic interactions between proteins with similar structure. Upon activation, ZBP1 initiates a downstream signaling cascade leading to programmed cell death, a process mediated by RIPK3 via the RHIM motif. PKZ was identified in fish, and contains two Zα domains at the N-terminus. PKZ is essential for normal growth and development and may contribute to the regulation of immune system function in fish. Interestingly, some pathogenic microorganisms also encode Zα domain proteins, such as, Vaccinia virus and Cyprinid Herpesvirus. Zα domain proteins derived from pathogenic microorganisms have been demonstrated to be pivotal contributors in impeding the host immune response and promoting virus replication and spread. This review focuses on the mammalian Zα domain proteins: ADAR1 and ZBP1, and thoroughly elucidates their functions in the immune response.
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Affiliation(s)
- Yuhan Zhong
- Laboratory of Liver Transplantation, Frontiers Science Center for Disease-Related Molecular Network, West China Hospital, Sichuan University, Chengdu, China
| | - Xiao Zhong
- Laboratory of Liver Transplantation, Frontiers Science Center for Disease-Related Molecular Network, West China Hospital, Sichuan University, Chengdu, China
- Institute of Life Sciences, Chongqing Medical University, Chongqing, China
| | - Liangjun Qiao
- Institute of Life Sciences, Chongqing Medical University, Chongqing, China
| | - Hong Wu
- Laboratory of Liver Transplantation, Frontiers Science Center for Disease-Related Molecular Network, West China Hospital, Sichuan University, Chengdu, China
| | - Chang Liu
- Division of Liver, Department of General Surgery, West China Hospital, Sichuan University, Chengdu, China
| | - Ting Zhang
- Laboratory of Liver Transplantation, Frontiers Science Center for Disease-Related Molecular Network, West China Hospital, Sichuan University, Chengdu, China
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20
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Liang Z, Goradia A, Walkley CR, Heraud-Farlow JE. Generation of a new Adar1p150 -/- mouse demonstrates isoform-specific roles in embryonic development and adult homeostasis. RNA (NEW YORK, N.Y.) 2023; 29:1325-1338. [PMID: 37290963 PMCID: PMC10573302 DOI: 10.1261/rna.079509.122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 05/09/2023] [Indexed: 06/10/2023]
Abstract
The RNA editing enzyme adenosine deaminase acting on RNA 1 (ADAR1) is an essential regulator of the innate immune response to both cellular and viral double-stranded RNA (dsRNA). Adenosine-to-inosine (A-to-I) editing by ADAR1 modifies the sequence and structure of endogenous dsRNA and masks it from the cytoplasmic dsRNA sensor melanoma differentiation-associated protein 5 (MDA5), preventing innate immune activation. Loss-of-function mutations in ADAR are associated with rare autoinflammatory disorders including Aicardi-Goutières syndrome (AGS), defined by a constitutive systemic up-regulation of type I interferon (IFN). The murine Adar gene encodes two protein isoforms with distinct functions: ADAR1p110 is constitutively expressed and localizes to the nucleus, whereas ADAR1p150 is primarily cytoplasmic and is inducible by IFN. Recent studies have demonstrated the critical requirement for ADAR1p150 to suppress innate immune activation by self dsRNAs. However, detailed in vivo characterization of the role of ADAR1p150 during development and in adult mice is lacking. We identified a new ADAR1p150-specific knockout mouse mutant based on a single nucleotide deletion that resulted in the loss of the ADAR1p150 protein without affecting ADAR1p110 expression. The Adar1p150 -/- died embryonically at E11.5-E12.5 accompanied by cell death in the fetal liver and an activated IFN response. Somatic loss of ADAR1p150 in adults was lethal and caused rapid hematopoietic failure, demonstrating an ongoing requirement for ADAR1p150 in vivo. The generation and characterization of this mouse model demonstrates the essential role of ADAR1p150 in vivo and provides a new tool for dissecting the functional differences between ADAR1 isoforms and their physiological contributions.
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Affiliation(s)
- Zhen Liang
- St. Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia
- Department of Medicine, Eastern Hill Precinct, Melbourne Medical School, University of Melbourne, Fitzroy, Victoria 3065, Australia
| | - Ankita Goradia
- St. Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia
| | - Carl R Walkley
- St. Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia
- Department of Medicine, Eastern Hill Precinct, Melbourne Medical School, University of Melbourne, Fitzroy, Victoria 3065, Australia
| | - Jacki E Heraud-Farlow
- St. Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia
- Department of Medicine, Eastern Hill Precinct, Melbourne Medical School, University of Melbourne, Fitzroy, Victoria 3065, Australia
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21
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Lamichhane PP, Samir P. Cellular Stress: Modulator of Regulated Cell Death. BIOLOGY 2023; 12:1172. [PMID: 37759572 PMCID: PMC10525759 DOI: 10.3390/biology12091172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 08/22/2023] [Accepted: 08/22/2023] [Indexed: 09/29/2023]
Abstract
Cellular stress response activates a complex program of an adaptive response called integrated stress response (ISR) that can allow a cell to survive in the presence of stressors. ISR reprograms gene expression to increase the transcription and translation of stress response genes while repressing the translation of most proteins to reduce the metabolic burden. In some cases, ISR activation can lead to the assembly of a cytoplasmic membraneless compartment called stress granules (SGs). ISR and SGs can inhibit apoptosis, pyroptosis, and necroptosis, suggesting that they guard against uncontrolled regulated cell death (RCD) to promote organismal homeostasis. However, ISR and SGs also allow cancer cells to survive in stressful environments, including hypoxia and during chemotherapy. Therefore, there is a great need to understand the molecular mechanism of the crosstalk between ISR and RCD. This is an active area of research and is expected to be relevant to a range of human diseases. In this review, we provided an overview of the interplay between different cellular stress responses and RCD pathways and their modulation in health and disease.
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Affiliation(s)
| | - Parimal Samir
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA
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22
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Maelfait J, Rehwinkel J. The Z-nucleic acid sensor ZBP1 in health and disease. J Exp Med 2023; 220:e20221156. [PMID: 37450010 PMCID: PMC10347765 DOI: 10.1084/jem.20221156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 06/28/2023] [Accepted: 07/05/2023] [Indexed: 07/18/2023] Open
Abstract
Nucleic acid sensing is a central process in the immune system, with far-reaching roles in antiviral defense, autoinflammation, and cancer. Z-DNA binding protein 1 (ZBP1) is a sensor for double-stranded DNA and RNA helices in the unusual left-handed Z conformation termed Z-DNA and Z-RNA. Recent research established ZBP1 as a key upstream regulator of cell death and proinflammatory signaling. Recognition of Z-DNA/RNA by ZBP1 promotes host resistance to viral infection but can also drive detrimental autoinflammation. Additionally, ZBP1 has interesting roles in cancer and other disease settings and is emerging as an attractive target for therapy.
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Affiliation(s)
- Jonathan Maelfait
- VIB-UGent Center for Inflammation Research, Ghent, Belgium
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Jan Rehwinkel
- Medical Research Council Human Immunology Unit, Medical Research Council Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
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23
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DeAntoneo C, Herbert A, Balachandran S. Z-form nucleic acid-binding protein 1 (ZBP1) as a sensor of viral and cellular Z-RNAs: walking the razor's edge. Curr Opin Immunol 2023; 83:102347. [PMID: 37276820 PMCID: PMC10526625 DOI: 10.1016/j.coi.2023.102347] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 05/01/2023] [Accepted: 05/02/2023] [Indexed: 06/07/2023]
Abstract
Z-form nucleic acid-binding protein 1 (ZBP1) detects viral Z-form RNAs (Z-RNAs), activates receptor-interacting protein kinase 3, and triggers cell death during both RNA and DNA virus infections. Such cell death promotes virus clearance by eliminating infected cells and galvanizing antiviral immunity, and is thus often targeted for evasion by virus-encoded suppressors. Recent evidence demonstrates that ZBP1 can also be activated by cellular Z-RNAs transcribed from endogenous retroelements within mammalian genomes. These cellular Z-RNAs, if not edited and neutralized by adenosine deaminase RNA-specific 1, trigger ZBP1-dependent cell death and inflammation, which may drive disease in Aicardi-Goutière's syndrome and related interferonopathies. Thus, while well-controlled activation of ZBP1 by viral Z-RNAs during infections is beneficial, the same pathway can have harmful consequences when inappropriately triggered by cellular Z-RNAs in other disease settings.
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Affiliation(s)
- Carly DeAntoneo
- Drexel University College of Medicine, 2900 W. Queen Lane, Philadelphia, PA 19129, USA; Center for Immunology, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Alan Herbert
- InsideOutBio, 42 8th Street, Charlestown, MA, USA
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24
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Guo X, Liu S, Sheng Y, Zenati M, Billiar T, Herbert A, Wang Q. ADAR1 Zα domain P195A mutation activates the MDA5-dependent RNA-sensing signaling pathway in brain without decreasing overall RNA editing. Cell Rep 2023; 42:112733. [PMID: 37421629 PMCID: PMC10691306 DOI: 10.1016/j.celrep.2023.112733] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 05/03/2023] [Accepted: 06/16/2023] [Indexed: 07/10/2023] Open
Abstract
Variants of the RNA-editing enzyme ADAR1 cause Aicardi-Goutières syndrome (AGS), in which severe inflammation occurs in the brain due to innate immune activation. Here, we analyze the RNA-editing status and innate immune activation in an AGS mouse model that carries the Adar P195A mutation in the N terminus of the ADAR1 p150 isoform, the equivalent of the P193A human Zα variant causal for disease. This mutation alone can cause interferon-stimulated gene (ISG) expression in the brain, especially in the periventricular areas, reflecting the pathologic feature of AGS. However, in these mice, ISG expression does not correlate with an overall decrease in RNA editing. Rather, the enhanced ISG expression in the brain due to the P195A mutant is dose dependent. Our findings indicate that ADAR1 can regulate innate immune responses through Z-RNA binding without changing overall RNA editing.
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Affiliation(s)
- Xinfeng Guo
- Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Silvia Liu
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Yi Sheng
- Magee-Women's Research Institute, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Mazen Zenati
- Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Timothy Billiar
- Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | | | - Qingde Wang
- Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; VA Pittsburgh Healthcare System, Pittsburgh, PA 15240, USA.
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25
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Rivera M, Zhang H, Pham J, Isquith J, Zhou QJ, Sasik R, Mark A, Ma W, Holm F, Fisch KM, Kuo DJ, Jamieson C, Jiang Q. Malignant A-to-I RNA editing by ADAR1 drives T-cell acute lymphoblastic leukemia relapse via attenuating dsRNA sensing. RESEARCH SQUARE 2023:rs.3.rs-2444524. [PMID: 37398458 PMCID: PMC10312963 DOI: 10.21203/rs.3.rs-2444524/v2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Leukemia initiating cells (LICs) are regarded as the origin of leukemia relapse and therapeutic resistance. Identifying direct stemness determinants that fuel LIC self-renewal is critical for developing targeted approaches to eliminate LICs and prevent relapse. Here, we show that the RNA editing enzyme ADAR1 is a crucial stemness factor that promotes LIC self-renewal by attenuating aberrant double-stranded RNA (dsRNA) sensing. Elevated adenosine-to-inosine (A-to-I) editing is a common attribute of relapsed T-ALL regardless of molecular subtypes. Consequently, knockdown of ADAR1 severely inhibits LIC self-renewal capacity and prolongs survival in T-ALL PDX models. Mechanistically, ADAR1 directs hyper-editing of immunogenic dsRNA and retains unedited nuclear dsRNA to avoid detection by the innate immune sensor MDA5. Moreover, we uncovered that the cell intrinsic level of MDA5 dictates the dependency on ADAR1-MDA5 axis in T-ALL. Collectively, our results show that ADAR1 functions as a self-renewal factor that limits the sensing of endogenous dsRNA. Thus, targeting ADAR1 presents a safe and effective therapeutic strategy for eliminating T-ALL LICs.
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Affiliation(s)
- Maria Rivera
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA, USA
- Moores Cancer Center, La Jolla, CA 92037, USA
| | - Haoran Zhang
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA, USA
- Moores Cancer Center, La Jolla, CA 92037, USA
| | - Jessica Pham
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Jane Isquith
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Qingchen Jenny Zhou
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA, USA
- Moores Cancer Center, La Jolla, CA 92037, USA
| | - Roman Sasik
- Center for Computational Biology & Bioinformatics (CCBB), University of California, San Diego, La Jolla, 92093-0681
| | - Adam Mark
- Center for Computational Biology & Bioinformatics (CCBB), University of California, San Diego, La Jolla, 92093-0681
| | - Wenxue Ma
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Frida Holm
- Department of Women’s and Children’s Health, Division of Pediatric Oncology and Surgery, Karolinska Institutet, Sweden
| | - Kathleen M Fisch
- Center for Computational Biology & Bioinformatics (CCBB), University of California, San Diego, La Jolla, 92093-0681
- Department of Obstetrics, Gynecology & Reproductive Sciences, University of California, San Diego, La Jolla, CA
| | - Dennis John Kuo
- Moores Cancer Center, La Jolla, CA 92037, USA
- Division of Pediatric Hematology-Oncology, Rady Children’s Hospital San Diego, University of California, San Diego, CA
| | - Catriona Jamieson
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA, USA
- Moores Cancer Center, La Jolla, CA 92037, USA
| | - Qingfei Jiang
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA, USA
- Moores Cancer Center, La Jolla, CA 92037, USA
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26
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Kleinova R, Rajendra V, Leuchtenberger AF, Lo Giudice C, Vesely C, Kapoor U, Tanzer A, Derdak S, Picardi E, Jantsch MF. The ADAR1 editome reveals drivers of editing-specificity for ADAR1-isoforms. Nucleic Acids Res 2023; 51:4191-4207. [PMID: 37026479 PMCID: PMC10201426 DOI: 10.1093/nar/gkad265] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 03/10/2023] [Accepted: 04/06/2023] [Indexed: 04/08/2023] Open
Abstract
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.
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Affiliation(s)
- Renata Kleinova
- Center for Anatomy and Cell Biology, Division of Cell and Developmental Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
| | - Vinod Rajendra
- Center for Anatomy and Cell Biology, Division of Cell and Developmental Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
| | - Alina F Leuchtenberger
- Center for Integrative Bioinformatics Vienna (CIBIV) Max Perutz Labs, University of Vienna and Medical University of Vienna, Campus Vienna Biocenter 5, A-1030 Vienna, Austria
| | - Claudio Lo Giudice
- Department of Bioscience, Biotechnology and Biopharmaceutics, University of Bari Aldo Moro, University Campus “Ernesto Quagliariello”, Via Orabona 4, Bari, Italy
| | - Cornelia Vesely
- Center for Anatomy and Cell Biology, Division of Cell and Developmental Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
| | - Utkarsh Kapoor
- Center for Anatomy and Cell Biology, Division of Cell and Developmental Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
| | - Andrea Tanzer
- Center for Anatomy and Cell Biology, Division of Cell and Developmental Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
| | - Sophia Derdak
- Core Facilities Medical University of Vienna, Spitalgasse 23, A-1090 Vienna, Austria
| | - Ernesto Picardi
- Department of Bioscience, Biotechnology and Biopharmaceutics, University of Bari Aldo Moro, University Campus “Ernesto Quagliariello”, Via Orabona 4, Bari, Italy
- Institute of Biomembranes and Bioenergetics (IBBE), National Research Council (CNR), Via Amendola 122, Bari, Italy
| | - Michael F Jantsch
- Center for Anatomy and Cell Biology, Division of Cell and Developmental Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
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27
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Zheng J, Shi W, Yang Z, Chen J, Qi A, Yang Y, Deng Y, Yang D, Song N, Song B, Luo D. RIG-I-like receptors: Molecular mechanism of activation and signaling. Adv Immunol 2023; 158:1-74. [PMID: 37453753 DOI: 10.1016/bs.ai.2023.03.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/18/2023]
Abstract
During RNA viral infection, RIG-I-like receptors (RLRs) recognize the intracellular pathogenic RNA species derived from viral replication and activate antiviral innate immune response by stimulating type 1 interferon expression. Three RLR members, namely, RIG-I, MDA5, and LGP2 are homologous and belong to a subgroup of superfamily 2 Helicase/ATPase that is preferably activated by double-stranded RNA. RLRs are significantly different in gene architecture, RNA ligand preference, activation, and molecular functions. As switchable macromolecular sensors, RLRs' activities are tightly regulated by RNA ligands, ATP, posttranslational modifications, and cellular cofactors. We provide a comprehensive review of the structure and function of the RLRs and summarize the molecular understanding of sensing and signaling events during the RLR activation process. The key roles RLR signaling play in both anti-infection and immune disease conditions highlight the therapeutic potential in targeting this important molecular pathway.
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Affiliation(s)
- Jie Zheng
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, UCAS, Hangzhou, China; Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
| | - Wenjia Shi
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Ziqun Yang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Jin Chen
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Ao Qi
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, UCAS, Hangzhou, China; Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Yulin Yang
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, UCAS, Hangzhou, China; Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Ying Deng
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Dongyuan Yang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Ning Song
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Bin Song
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Dahai Luo
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore; NTU Institute of Structural Biology, Nanyang Technological University, Singapore, Singapore.
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28
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Liang Z, Chalk AM, Taylor S, Goradia A, Heraud‐Farlow JE, Walkley CR. The phenotype of the most common human ADAR1p150 Zα mutation P193A in mice is partially penetrant. EMBO Rep 2023; 24:e55835. [PMID: 36975179 PMCID: PMC10157378 DOI: 10.15252/embr.202255835] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 02/13/2023] [Accepted: 02/28/2023] [Indexed: 03/29/2023] Open
Abstract
ADAR1 -mediated A-to-I RNA editing is a self-/non-self-discrimination mechanism for cellular double-stranded RNAs. ADAR mutations are one cause of Aicardi-Goutières Syndrome, an inherited paediatric encephalopathy, classed as a "Type I interferonopathy." The most common ADAR1 mutation is a proline 193 alanine (p.P193A) mutation, mapping to the ADAR1p150 isoform-specific Zα domain. Here, we report the development of an independent murine P195A knock-in mouse, homologous to human P193A. The Adar1P195A/P195A mice are largely normal and the mutation is well tolerated. When the P195A mutation is compounded with an Adar1 null allele (Adar1P195A/- ), approximately half the animals are runted with a shortened lifespan while the remaining Adar1P195A/- animals are normal, contrasting with previous reports. The phenotype of the Adar1P195A/- animals is both associated with the parental genotype and partly non-genetic/environmental. Complementation with an editing-deficient ADAR1 (Adar1P195A/E861A ), or the loss of MDA5, rescues phenotypes in the Adar1P195A/- mice.
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Affiliation(s)
- Zhen Liang
- St Vincent's Institute of Medical ResearchFitzroyVic.Australia
- Department of Medicine, Eastern Hill Precinct, Melbourne Medical SchoolUniversity of MelbourneFitzroyVic.Australia
| | - Alistair M Chalk
- St Vincent's Institute of Medical ResearchFitzroyVic.Australia
- Department of Medicine, Eastern Hill Precinct, Melbourne Medical SchoolUniversity of MelbourneFitzroyVic.Australia
| | - Scott Taylor
- St Vincent's Institute of Medical ResearchFitzroyVic.Australia
| | - Ankita Goradia
- St Vincent's Institute of Medical ResearchFitzroyVic.Australia
| | - Jacki E Heraud‐Farlow
- St Vincent's Institute of Medical ResearchFitzroyVic.Australia
- Department of Medicine, Eastern Hill Precinct, Melbourne Medical SchoolUniversity of MelbourneFitzroyVic.Australia
| | - Carl R Walkley
- St Vincent's Institute of Medical ResearchFitzroyVic.Australia
- Department of Medicine, Eastern Hill Precinct, Melbourne Medical SchoolUniversity of MelbourneFitzroyVic.Australia
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29
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Corbet GA, Burke JM, Parker R. Nucleic acid-protein condensates in innate immune signaling. EMBO J 2023; 42:e111870. [PMID: 36178199 PMCID: PMC10068312 DOI: 10.15252/embj.2022111870] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 07/24/2022] [Accepted: 09/19/2022] [Indexed: 11/09/2022] Open
Abstract
The presence of foreign nucleic acids in the cytosol is a marker of infection. Cells have sensors, also known as pattern recognition receptors (PRRs), in the cytosol that detect foreign nucleic acid and initiate an innate immune response. Recent studies have reported the condensation of multiple PRRs including PKR, NLRP6, and cGAS, with their nucleic acid activators into discrete nucleoprotein assemblies. Nucleic acid-protein condensates form due to multivalent interactions and can create high local concentrations of components. The formation of PRR-containing condensates may alter the magnitude or timing of PRR activation. In addition, unique condensates form following RNase L activation or during paracrine signaling from virally infected cells that may play roles in antiviral defense. These observations suggest that condensate formation may be a conserved mechanism that cells use to regulate activation of the innate immune response and open an avenue for further investigation into the composition and function of these condensates. Here we review the nucleic acid-protein granules that are implicated in the innate immune response, discuss general consequences of condensate formation and signal transduction, as well as what outstanding questions remain.
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Affiliation(s)
- Giulia A Corbet
- Department of BiochemistryUniversity of ColoradoBoulderCOUSA
| | - James M Burke
- Department of BiochemistryUniversity of ColoradoBoulderCOUSA
- Present address:
Department of Molecular MedicineUniversity of Florida Scripps Biomedical ResearchJupiterFLUSA
| | - Roy Parker
- Department of BiochemistryUniversity of ColoradoBoulderCOUSA
- Howard Hughes Medical InstituteChevy ChaseMDUSA
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30
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Nakahama T, Kawahara Y. The RNA-editing enzyme ADAR1: a regulatory hub that tunes multiple dsRNA-sensing pathways. Int Immunol 2023; 35:123-133. [PMID: 36469491 DOI: 10.1093/intimm/dxac056] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 11/29/2022] [Indexed: 12/12/2022] Open
Abstract
Adenosine deaminase acting on RNA 1 (ADAR1) is an RNA-editing enzyme that catalyzes adenosine-to-inosine conversions in double-stranded RNAs (dsRNAs). In mammals, ADAR1 is composed of two isoforms: a nuclear short p110 isoform and a cytoplasmic long p150 isoform. Whereas both isoforms contain right-handed dsRNA-binding and deaminase domains, ADAR1 p150 harbors a Zα domain that binds to left-handed dsRNAs, termed Z-RNAs. Myeloma differentiation-associated gene 5 (MDA5) sensing of endogenous dsRNAs as non-self leads to the induction of type I interferon (IFN)-stimulated genes, but recent studies revealed that ADAR1 p150-mediated RNA editing, but not ADAR1 p110, prevents this MDA5-mediated sensing. ADAR1 p150-specific RNA-editing sites are present and at least a Zα domain-Z-RNA interaction is required for this specificity. Mutations in the ADAR1 gene cause Aicardi-Goutières syndrome (AGS), an infant encephalopathy with type I IFN overproduction. Insertion of a point mutation in the Zα domain of the Adar1 gene induces AGS-like encephalopathy in mice, which is rescued by concurrent deletion of MDA5. This finding indicates that impaired ADAR1 p150-mediated RNA-editing is a mechanism underlying AGS caused by an ADAR1 mutation. ADAR1 p150 also prevents ZBP1 sensing of endogenous Z-RNA, which leads to programmed cell death, via the Zα domain and its RNA-editing activity. Furthermore, ADAR1 prevents protein kinase R (PKR) sensing of endogenous right-handed dsRNAs, which leads to translational shutdown and growth arrest. Thus, ADAR1 acts as a regulatory hub that blocks sensing of endogenous dsRNAs as non-self by multiple sensor proteins, both in RNA editing-dependent and -independent manners, and is a potential therapeutic target for diseases, especially cancer.
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Affiliation(s)
- Taisuke Nakahama
- Department of RNA Biology and Neuroscience, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan.,Integrated Frontier Research for Medical Science Division and RNA Frontier Science Division, Institute for Open and Transdisciplinary Research Initiatives (OTRI), Osaka University, Suita, Osaka 565-0871, Japan.,Division of Microbiology and Immunology, Center for Infectious Disease Education and Research (CiDER), Osaka University, Suita, Osaka 565-0871, Japan
| | - Yukio Kawahara
- Department of RNA Biology and Neuroscience, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan.,Integrated Frontier Research for Medical Science Division and RNA Frontier Science Division, Institute for Open and Transdisciplinary Research Initiatives (OTRI), Osaka University, Suita, Osaka 565-0871, Japan.,Division of Microbiology and Immunology, Center for Infectious Disease Education and Research (CiDER), Osaka University, Suita, Osaka 565-0871, Japan
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31
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Karki R, Kanneganti TD. ADAR1 and ZBP1 in innate immunity, cell death, and disease. Trends Immunol 2023; 44:201-216. [PMID: 36710220 PMCID: PMC9974732 DOI: 10.1016/j.it.2023.01.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 12/28/2022] [Accepted: 01/04/2023] [Indexed: 01/28/2023]
Abstract
ADAR1 and ZBP1 are the only two mammalian proteins that contain Zα domains, which are thought to bind to nucleic acids in the Z-conformation. These two molecules are crucial in regulating diverse biological processes. While ADAR1-mediated RNA editing supports host survival and development, ZBP1-mediated immune responses provide host defense against infection and disease. Recent studies have expanded our understanding of the functions of ADAR1 and ZBP1 beyond their classical roles and established their fundamental regulation of innate immune responses, including NLRP3 inflammasome activation, inflammation, and cell death. Their roles in these processes have physiological impacts across development, infectious and inflammatory diseases, and cancer. In this review, we discuss the functions of ADAR1 and ZBP1 in regulating innate immune responses in development and disease.
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Affiliation(s)
- Rajendra Karki
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
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32
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RBP-RNA interactions in the control of autoimmunity and autoinflammation. Cell Res 2023; 33:97-115. [PMID: 36599968 PMCID: PMC9892603 DOI: 10.1038/s41422-022-00752-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Accepted: 11/07/2022] [Indexed: 01/06/2023] Open
Abstract
Autoimmunity and autoinflammation arise from aberrant immunological and inflammatory responses toward self-components, contributing to various autoimmune diseases and autoinflammatory diseases. RNA-binding proteins (RBPs) are essential for immune cell development and function, mainly via exerting post-transcriptional regulation of RNA metabolism and function. Functional dysregulation of RBPs and abnormities in RNA metabolism are closely associated with multiple autoimmune or autoinflammatory disorders. Distinct RBPs play critical roles in aberrant autoreactive inflammatory responses via orchestrating a complex regulatory network consisting of DNAs, RNAs and proteins within immune cells. In-depth characterizations of RBP-RNA interactomes during autoimmunity and autoinflammation will lead to a better understanding of autoimmune pathogenesis and facilitate the development of effective therapeutic strategies. In this review, we summarize and discuss the functions of RBP-RNA interactions in controlling aberrant autoimmune inflammation and their potential as biomarkers and therapeutic targets.
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33
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Adamska JZ, Verma R, Gupta S, Hagan T, Wimmers F, Floyd K, Li Q, Valore EV, Wang Y, Trisal M, Vilches-Moure JG, Subramaniam S, Walkley CR, Suthar MS, Li JB, Pulendran B. Ablation of Adar1 in myeloid cells imprints a global antiviral state in the lung and heightens early immunity against SARS-CoV-2. Cell Rep 2023; 42:112038. [PMID: 36732946 PMCID: PMC9842623 DOI: 10.1016/j.celrep.2023.112038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 11/25/2022] [Accepted: 01/11/2023] [Indexed: 01/18/2023] Open
Abstract
Under normal homeostatic conditions, self-double-stranded RNA (self-dsRNA) is modified by adenosine deaminase acting on RNA 1 (ADAR1) to prevent the induction of a type I interferon-mediated inflammatory cascade. Antigen-presenting cells (APCs) sense pathogen-associated molecular patterns, such as dsRNA, to activate the immune response. The impact of ADAR1 on the function of APCs and the consequences to immunity are poorly understood. Here, we show that ADAR1 deletion in CD11c+ APCs leads to (1) a skewed myeloid cell compartment enriched in inflammatory cDC2-like cells, (2) enhanced numbers of activated tissue resident memory T cells in the lung, and (3) the imprinting of a broad antiviral transcriptional signature across both immune and non-immune cells. The resulting changes can be partially reversed by blocking IFNAR1 signaling and promote early resistance against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Our study provides insight into the consequences of self-dsRNA sensing in APCs on the immune system.
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Affiliation(s)
- Julia Z Adamska
- Institute for Immunity, Transplantation and Infection, Stanford University School of Medicine, Stanford University, Stanford, CA 94304, USA; Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Rohit Verma
- Institute for Immunity, Transplantation and Infection, Stanford University School of Medicine, Stanford University, Stanford, CA 94304, USA
| | - Shakti Gupta
- Department of Bioengineering, University of California, San Diego, San Diego, CA 92093, USA
| | - Thomas Hagan
- Division of Infectious Diseases, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Florian Wimmers
- Institute for Immunity, Transplantation and Infection, Stanford University School of Medicine, Stanford University, Stanford, CA 94304, USA
| | - Katharine Floyd
- Department of Pediatrics, Department of Microbiology and Immunology, Emory Vaccine Center, Emory National Primate Center, Emory School of Medicine, Atlanta, GA 30329, USA
| | - Qin Li
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Erika V Valore
- Institute for Immunity, Transplantation and Infection, Stanford University School of Medicine, Stanford University, Stanford, CA 94304, USA
| | - Yanli Wang
- Institute for Immunity, Transplantation and Infection, Stanford University School of Medicine, Stanford University, Stanford, CA 94304, USA
| | - Meera Trisal
- Institute for Immunity, Transplantation and Infection, Stanford University School of Medicine, Stanford University, Stanford, CA 94304, USA
| | - José G Vilches-Moure
- Department of Comparative Medicine, Stanford University, Stanford, CA 94305, USA
| | - Shankar Subramaniam
- Department of Bioengineering, University of California, San Diego, San Diego, CA 92093, USA
| | - Carl R Walkley
- St. Vincent's Institute of Medical Research, Fitzroy, VIC 3065, Australia; Department of Medicine, St. Vincent's Hospital, University of Melbourne, Fitzroy, VIC 3065, Australia
| | - Mehul S Suthar
- Department of Pediatrics, Department of Microbiology and Immunology, Emory Vaccine Center, Emory National Primate Center, Emory School of Medicine, Atlanta, GA 30329, USA
| | - Jin Billy Li
- Department of Bioengineering, University of California, San Diego, San Diego, CA 92093, USA
| | - Bali Pulendran
- Institute for Immunity, Transplantation and Infection, Stanford University School of Medicine, Stanford University, Stanford, CA 94304, USA; Department of Pathology, Stanford University, Stanford, CA 94305, USA; Department of Microbiology & Immunology, Stanford University, Stanford, CA 94305, USA.
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34
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Hu SB, Heraud-Farlow J, Sun T, Liang Z, Goradia A, Taylor S, Walkley CR, Li JB. ADAR1p150 Prevents MDA5 and PKR Activation via Distinct Mechanisms to Avert Fatal Autoinflammation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.25.525475. [PMID: 36747811 PMCID: PMC9900771 DOI: 10.1101/2023.01.25.525475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Effective immunity requires the innate immune system to distinguish foreign (non-self) nucleic acids from cellular (self) nucleic acids. Cellular double-stranded RNAs (dsRNAs) are edited by the RNA editing enzyme ADAR1 to prevent their dsRNA structure pattern being recognized as viral dsRNA by cytoplasmic dsRNA sensors including MDA5, PKR and ZBP1. A loss of ADAR1-mediated RNA editing of cellular dsRNA activates MDA5. However, additional RNA editing-independent functions of ADAR1 have been proposed, but a specific mechanism has not been delineated. We now demonstrate that the loss of ADAR1-mediated RNA editing specifically activates MDA5, while loss of the cytoplasmic ADAR1p150 isoform or its dsRNA binding activity enabled PKR activation. Deleting both MDA5 and PKR resulted in complete rescue of the embryonic lethality of Adar1p150 -/- mice to adulthood, contrasting with the limited or no rescue by removing MDA5, PKR or ZBP1 alone, demonstrating that this is a species conserved function of ADAR1p150. Our findings demonstrate that MDA5 and PKR are the primary in vivo effectors of fatal autoinflammation following the loss of ADAR1p150.
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35
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Gan WL, Ng L, Ng BYL, Chen L. Recent Advances in Adenosine-to-Inosine RNA Editing in Cancer. Cancer Treat Res 2023; 190:143-179. [PMID: 38113001 DOI: 10.1007/978-3-031-45654-1_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
RNA epigenetics, or epitranscriptome, is a growing group of RNA modifications historically classified into two categories: RNA editing and RNA modification. RNA editing is usually understood as post-transcriptional RNA processing (except capping, splicing and polyadenylation) that changes the RNA nucleotide sequence encoded by the genome. This processing can be achieved through the insertion or deletion of nucleotides or deamination of nucleobases, generating either standard nucleotides such as uridine (U) or the rare nucleotide inosine (I). Adenosine-to-inosine (A-to-I) RNA editing is the most prevalent type of RNA modification in mammals and is catalyzed by adenosine deaminase acting on the RNA (ADAR) family of enzymes that recognize double-stranded RNAs (dsRNAs). Inosine mimics guanosine (G) in base pairing with cytidine (C), thereby A-to-I RNA editing alters dsRNA secondary structure. Inosine is also recognized as guanosine by the splicing and translation machineries, resulting in mRNA alternative splicing and protein recoding. Therefore, A-to-I RNA editing is an important mechanism that causes and regulates "RNA mutations" in both normal physiology and diseases including cancer. In this chapter, we reviewed current paradigms and developments in the field of A-to-I RNA editing in the context of cancer.
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Affiliation(s)
- Wei Liang Gan
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore, 117599, Singapore
| | - Larry Ng
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore, 117599, Singapore
| | - Bryan Y L Ng
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore, 117599, Singapore
| | - Leilei Chen
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore, 117599, Singapore.
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117594, Singapore.
- NUS Centre for Cancer Research, Yong Loo Lin School of Medicine, National University Singapore, Singapore, Singapore.
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36
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Guo X, Steinman RA, Sheng Y, Cao G, Wiley CA, Wang Q. An AGS-associated mutation in ADAR1 catalytic domain results in early-onset and MDA5-dependent encephalopathy with IFN pathway activation in the brain. J Neuroinflammation 2022; 19:285. [PMID: 36457126 PMCID: PMC9714073 DOI: 10.1186/s12974-022-02646-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 11/15/2022] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Aicardi-Goutières syndrome (AGS) is a severe neurodegenerative disease with clinical features of early-onset encephalopathy and progressive loss of intellectual abilities and motor control. Gene mutations in seven protein-coding genes have been found to be associated with AGS. However, the causative role of these mutations in the early-onset neuropathogenesis has not been demonstrated in animal models, and the mechanism of neurodegeneration of AGS remains ambiguous. METHODS Via CRISPR/Cas-9 technology, we established a mutant mouse model in which a genetic mutation found in AGS patients at the ADAR1 coding gene (Adar) loci was introduced into the mouse genome. A mouse model carrying double gene mutations encoding ADAR1 and MDA-5 was prepared using a breeding strategy. Phenotype, gene expression, RNA sequencing, innate immune pathway activation, and pathologic studies including RNA in situ hybridization (ISH) and immunohistochemistry were used for characterization of the mouse models to determine potential disease mechanisms. RESULTS We established a mouse model bearing a mutation in the catalytic domain of ADAR1, the D1113H mutation found in AGS patients. With this mouse model, we demonstrated a causative role of this mutation for the early-onset brain injuries in AGS and determined the signaling pathway underlying the neuropathogenesis. First, this mutation altered the RNA editing profile in neural transcripts and led to robust IFN-stimulated gene (ISG) expression in the brain. By ISH, the brains of mutant mice showed an unusual, multifocal increased expression of ISGs that was cell-type dependent. Early-onset astrocytosis and microgliosis and later stage calcification in the deep white matter areas were observed in the mutant mice. Brain ISG activation and neuroglial reaction were completely prevented in the Adar D1113H mutant mice by blocking RNA sensing through deletion of the cytosolic RNA receptor MDA-5. CONCLUSIONS The Adar D1113H mutation in the ADAR1 catalytic domain results in early-onset and MDA5-dependent encephalopathy with IFN pathway activation in the mouse brain.
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Affiliation(s)
- Xinfeng Guo
- Department of Surgery, University of Pittsburgh School of Medicine, 200 Lothrop Street, Pittsburgh, PA 15213 USA
| | - Richard A. Steinman
- Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA USA
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA USA
| | - Yi Sheng
- Magee Women Research Institute, University of Pittsburgh, Pittsburgh, PA USA
| | - Guodong Cao
- Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA USA
| | - Clayton A. Wiley
- Department of Pathology, School of Medicine, University of Pittsburgh, Scaife Hall, 200 Lothrop Street, Pittsburgh, PA 15213 USA
| | - Qingde Wang
- Department of Surgery, University of Pittsburgh School of Medicine, 200 Lothrop Street, Pittsburgh, PA 15213 USA
- V.A. Pittsburgh Health System, Pittsburgh, PA USA
- Pittsburgh Liver Research Center, University of Pittsburgh Medical Center and University of Pittsburgh School of Medicine, Pittsburgh, PA USA
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37
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BenDavid E, Pfaller CK, Pan Y, Samuel CE, Ma D. Host 5'-3' Exoribonuclease XRN1 Acts as a Proviral Factor for Measles Virus Replication by Downregulating the dsRNA-Activated Kinase PKR. J Virol 2022; 96:e0131922. [PMID: 36300942 PMCID: PMC9683022 DOI: 10.1128/jvi.01319-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 09/22/2022] [Indexed: 11/20/2022] Open
Abstract
Many negative-sense RNA viruses, including measles virus (MeV), are thought to carry out much of their viral replication in cytoplasmic membraneless foci known as inclusion bodies (IBs). The mechanisms by which IBs facilitate efficient viral replication remain largely unknown but may involve an intricate network of regulation at the host-virus interface. Viruses are able to modulate such interactions by a variety of strategies including adaptation of their genomes and "hijacking" of host proteins. The latter possibility broadens the molecular reservoir available for a virus to enhance its replication and/or antagonize host antiviral responses. Here, we show that the cellular 5'-3' exoribonuclease, XRN1, is a host protein hijacked by MeV. We found that upon MeV infection, XRN1 is translocated to cytoplasmic IBs where it acts in a proviral manner by preventing the accumulation of double-stranded RNA (dsRNA) within the IBs. This leads to the suppression of the dsRNA-induced innate immune responses mediated via the protein kinase R (PKR)-integrated stress response (ISR) pathway. IMPORTANCE Measles virus remains a major global health threat due to its high transmissibility and significant morbidity in children and immunocompromised individuals. Although there is an effective vaccine against MeV, a large population in the world remains without access to the vaccine, contributing to more than 7,000,000 measles cases and 60,000 measles deaths in 2020 (CDC). For negative-sense RNA viruses including MeV, one active research area is the exploration of virus-host interactions occurring at cytoplasmic IBs where viral replication takes place. In this study we present evidence suggesting a model in which MeV IBs antagonize host innate immunity by recruiting XRN1 to reduce dsRNA accumulation and subsequent PKR kinase activation/ISR induction. In the absence of XRN1, the increased dsRNA level acts as a potent activator of the antiviral PKR/ISR pathway leading to suppression of global cap-dependent mRNA translation and inhibition of viral replication.
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Affiliation(s)
- Ethan BenDavid
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California, USA
| | | | - Yue Pan
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California, USA
| | - Charles E. Samuel
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California, USA
- Neuroscience Research Institute, University of California, Santa Barbara, California, USA
| | - Dzwokai Ma
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California, USA
- Neuroscience Research Institute, University of California, Santa Barbara, California, USA
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38
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Tang Q. Z-nucleic acids: Uncovering the functions from past to present. Eur J Immunol 2022; 52:1700-1711. [PMID: 36165274 PMCID: PMC9827954 DOI: 10.1002/eji.202249968] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 08/15/2022] [Accepted: 09/23/2022] [Indexed: 01/12/2023]
Abstract
Since Z-nucleic acid was identified in the 1970s, much is still unknown about its biological functions and nature in vivo. Recent studies on adenosine deaminase acting on RNA 1 (ADAR1) and Z-DNA-binding protein 1 (ZBP1) have highlighted its function in immune responses. Specifically, Z-RNAs, either endogenous or induced by viral infection, are sensed by ZBP1 and activate necroptosis. Z-RNAs act as the stimuli that induce innate immune responses through various pathways, including melanoma differentiation-associated protein 5 (MAD5)-mitochondrial antiviral-signaling protein (MAVS)-mediated type I IFN activation and proteinase kinase R (PKR)-dependent integrated stress response, and their immunostimulatory potential is curtailed by RNA editing conducted by ADAR1. Aberrant immune responses induced by Z-RNAs are associated with human diseases. They also induce pathogenesis in mice. Unlike Z-RNAs, the biological functions of Z-DNAs were barely studied, especially in mammals. Moreover, the origin or sequence preference of Z-nucleic acids requires further investigation. Such knowledge will expand our understanding of Z-nucleic acids, including from which genomic loci and under which circumstances they form, and the mechanisms by which they participate in the physiological activities. In this review, we provide insights in Z-nucleic acid research and highlight the unsolved puzzles.
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Affiliation(s)
- Qiannan Tang
- Shanghai Institute of ImmunologyDepartment of Immunology and MicrobiologyShanghai Jiao Tong University School of MedicineShanghaiChina,Centre for Immune‐Related Diseases at Shanghai Institute of ImmunologyRuijin Hospital, Shanghai Jiao Tong University School of MedicineShanghaiChina
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39
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Chen W, Li Y, Ruan GX, Huang H, Zhang R, Wang J, Ouyang Y, Li Y, Xu S, Ou X. Adenosine deaminase acting on RNA-1 is essential for early B lymphopoiesis. Cell Rep 2022; 41:111687. [DOI: 10.1016/j.celrep.2022.111687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 09/07/2022] [Accepted: 10/27/2022] [Indexed: 11/23/2022] Open
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40
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Li Y, Ruan GX, Chen W, Huang H, Zhang R, Wang J, Li Y, Xu S, Ou X. RNA-Editing Enzyme ADAR1 p150 Isoform Is Critical for Germinal Center B Cell Response. THE JOURNAL OF IMMUNOLOGY 2022; 209:1071-1082. [DOI: 10.4049/jimmunol.2200149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 07/11/2022] [Indexed: 01/04/2023]
Abstract
Abstract
Adenosine deaminase acting on RNA (ADAR)1 is the principal enzyme for adenosine-to-inosine editing, an RNA modification–avoiding cytosolic nucleic acid sensor’s activation triggered by endogenous dsRNAs. Two ADAR1 isoforms exist in mammals, a longer IFN-inducible and mainly cytoplasm-localized p150 isoform and a shorter constitutively expressed and primarily nucleus-localized p110 isoform. Studies of ADAR1 mutant mice have demonstrated that ADAR1 is essential for multiple physiological processes, including embryonic development, innate immune response, and B and T lymphocyte development. However, it remained unknown whether ADAR1 plays a role in the humoral immune response. In this study, we conditionally delete Adar1 in activated B cells and show that ADAR1-deficient mice have a defective T cell–dependent Ab response and diminished germinal center (GC) B cells. Using various double mutant mice concurrently deficient in ADAR1 and different downstream dsRNA sensors, we demonstrate that ADAR1 regulates the GC response by preventing hyperactivation of the melanoma differentiation-associated protein 5 (MDA5) but not the protein kinase R or RNase L pathway. We also show that p150 is exclusively responsible for ADAR1’s function in the GC response, and the p110 isoform cannot substitute for the p150’s role, even when p110 is constitutively expressed in the cytoplasm. We further demonstrated that the dsRNA-binding but not the RNA-editing activity is required for ADAR1’s function in the GC response. Thus, our data suggest that the ADAR1 p150 isoform plays a crucial role in regulating the GC B cell response.
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Affiliation(s)
- Yuxing Li
- *Harbin Institute of Technology, Harbin, China
- †Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
| | - Gui-Xin Ruan
- †Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
| | - Wenjing Chen
- †Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
| | - Hengjun Huang
- †Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
| | - Rui Zhang
- †Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
| | - Jing Wang
- †Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
| | - Yan Li
- †Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
| | - Shengli Xu
- ‡Singapore Immunology Network, Agency for Science, Technology and Research, Singapore; and
- §Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Xijun Ou
- †Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
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41
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Abstract
Mutations of the ADAR1 gene encoding an RNA deaminase cause severe diseases associated with chronic activation of type I interferon (IFN) responses, including Aicardi–Goutières syndrome and bilateral striatal necrosis1–3. The IFN-inducible p150 isoform of ADAR1 contains a Zα domain that recognizes RNA with an alternative left-handed double-helix structure, termed Z-RNA4,5. Hemizygous ADAR1 mutations in the Zα domain cause type I IFN-mediated pathologies in humans2,3 and mice6–8; however, it remains unclear how the interaction of ADAR1 with Z-RNA prevents IFN activation. Here we show that Z-DNA-binding protein 1 (ZBP1), the only other protein in mammals known to harbour Zα domains9, promotes type I IFN activation and fatal pathology in mice with impaired ADAR1 function. ZBP1 deficiency or mutation of its Zα domains reduced the expression of IFN-stimulated genes and largely prevented early postnatal lethality in mice with hemizygous expression of ADAR1 with mutated Zα domain (Adar1mZα/– mice). Adar1mZα/– mice showed upregulation and impaired editing of endogenous retroelement-derived complementary RNA reads, which represent a likely source of Z-RNAs activating ZBP1. Notably, ZBP1 promoted IFN activation and severe pathology in Adar1mZα/– mice in a manner independent of RIPK1, RIPK3, MLKL-mediated necroptosis and caspase-8-dependent apoptosis, suggesting a novel mechanism of action. Thus, ADAR1 prevents endogenous Z-RNA-dependent activation of pathogenic type I IFN responses by ZBP1, suggesting that ZBP1 could contribute to type I interferonopathies caused by ADAR1 mutations. ADAR1 prevents Z-RNA-dependent activation of pathogenic type I interferon responses by ZBP1, whose activity may contribute to pathology in type I interferonopathies with ADAR1 mutations.
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42
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de Reuver R, Verdonck S, Dierick E, Nemegeer J, Hessmann E, Ahmad S, Jans M, Blancke G, Van Nieuwerburgh F, Botzki A, Vereecke L, van Loo G, Declercq W, Hur S, Vandenabeele P, Maelfait J. ADAR1 prevents autoinflammation by suppressing spontaneous ZBP1 activation. Nature 2022; 607:784-789. [PMID: 35859175 DOI: 10.1038/s41586-022-04974-w] [Citation(s) in RCA: 78] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Accepted: 06/13/2022] [Indexed: 12/20/2022]
Abstract
The RNA-editing enzyme adenosine deaminase acting on RNA 1 (ADAR1) limits the accumulation of endogenous immunostimulatory double-stranded RNA (dsRNA)1. In humans, reduced ADAR1 activity causes the severe inflammatory disease Aicardi-Goutières syndrome (AGS)2. In mice, complete loss of ADAR1 activity is embryonically lethal3-6, and mutations similar to those found in patients with AGS cause autoinflammation7-12. Mechanistically, adenosine-to-inosine (A-to-I) base modification of endogenous dsRNA by ADAR1 prevents chronic overactivation of the dsRNA sensors MDA5 and PKR3,7-10,13,14. Here we show that ADAR1 also inhibits the spontaneous activation of the left-handed Z-nucleic acid sensor ZBP1. Activation of ZBP1 elicits caspase-8-dependent apoptosis and MLKL-mediated necroptosis of ADAR1-deficient cells. ZBP1 contributes to the embryonic lethality of Adar-knockout mice, and it drives early mortality and intestinal cell death in mice deficient in the expression of both ADAR and MAVS. The Z-nucleic-acid-binding Zα domain of ADAR1 is necessary to prevent ZBP1-mediated intestinal cell death and skin inflammation. The Zα domain of ADAR1 promotes A-to-I editing of endogenous Alu elements to prevent dsRNA formation through the pairing of inverted Alu repeats, which can otherwise induce ZBP1 activation. This shows that recognition of Alu duplex RNA by ZBP1 may contribute to the pathological features of AGS that result from the loss of ADAR1 function.
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Affiliation(s)
- Richard de Reuver
- VIB-UGent Center for Inflammation Research, Ghent, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Simon Verdonck
- VIB-UGent Center for Inflammation Research, Ghent, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Evelien Dierick
- VIB-UGent Center for Inflammation Research, Ghent, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Josephine Nemegeer
- VIB-UGent Center for Inflammation Research, Ghent, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Eline Hessmann
- VIB-UGent Center for Inflammation Research, Ghent, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Sadeem Ahmad
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Howard Hughes Medical Institute, Boston, MA, USA.,Program in Cellular and Molecular Medicine, Boston Children's Hospital, Howard Hughes Medical Institute, Boston, MA, USA
| | - Maude Jans
- VIB-UGent Center for Inflammation Research, Ghent, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Gillian Blancke
- VIB-UGent Center for Inflammation Research, Ghent, Belgium.,Department of Internal Medicine and Pediatrics, Ghent University, Ghent, Belgium
| | - Filip Van Nieuwerburgh
- NXTGNT, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium.,Laboratory of Pharmaceutical Biotechnology, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
| | | | - Lars Vereecke
- VIB-UGent Center for Inflammation Research, Ghent, Belgium.,Department of Internal Medicine and Pediatrics, Ghent University, Ghent, Belgium
| | - Geert van Loo
- VIB-UGent Center for Inflammation Research, Ghent, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Wim Declercq
- VIB-UGent Center for Inflammation Research, Ghent, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Sun Hur
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Howard Hughes Medical Institute, Boston, MA, USA.,Program in Cellular and Molecular Medicine, Boston Children's Hospital, Howard Hughes Medical Institute, Boston, MA, USA
| | - Peter Vandenabeele
- VIB-UGent Center for Inflammation Research, Ghent, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Jonathan Maelfait
- VIB-UGent Center for Inflammation Research, Ghent, Belgium. .,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium.
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43
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Hubbard NW, Ames JM, Maurano M, Chu LH, Somfleth KY, Gokhale NS, Werner M, Snyder JM, Lichauco K, Savan R, Stetson DB, Oberst A. ADAR1 mutation causes ZBP1-dependent immunopathology. Nature 2022; 607:769-775. [PMID: 35859177 PMCID: PMC9339495 DOI: 10.1038/s41586-022-04896-7] [Citation(s) in RCA: 76] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 05/23/2022] [Indexed: 01/22/2023]
Abstract
The RNA-editing enzyme ADAR1 is essential for the suppression of innate immune activation and pathology caused by aberrant recognition of self-RNA, a role it carries out by disrupting the duplex structure of endogenous double-stranded RNA species1,2. A point mutation in the sequence encoding the Z-DNA-binding domain (ZBD) of ADAR1 is associated with severe autoinflammatory disease3-5. ZBP1 is the only other ZBD-containing mammalian protein6, and its activation can trigger both cell death and transcriptional responses through the kinases RIPK1 and RIPK3, and the protease caspase 8 (refs. 7-9). Here we show that the pathology caused by alteration of the ZBD of ADAR1 is driven by activation of ZBP1. We found that ablation of ZBP1 fully rescued the overt pathology caused by ADAR1 alteration, without fully reversing the underlying inflammatory program caused by this alteration. Whereas loss of RIPK3 partially phenocopied the protective effects of ZBP1 ablation, combined deletion of caspase 8 and RIPK3, or of caspase 8 and MLKL, unexpectedly exacerbated the pathogenic effects of ADAR1 alteration. These findings indicate that ADAR1 is a negative regulator of sterile ZBP1 activation, and that ZBP1-dependent signalling underlies the autoinflammatory pathology caused by alteration of ADAR1.
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Affiliation(s)
| | - Joshua M Ames
- Department of Immunology, University of Washington, Seattle, WA, USA
| | - Megan Maurano
- Department of Immunology, University of Washington, Seattle, WA, USA
| | - Lan H Chu
- Department of Immunology, University of Washington, Seattle, WA, USA
| | - Kim Y Somfleth
- Department of Immunology, University of Washington, Seattle, WA, USA
| | - Nandan S Gokhale
- Department of Immunology, University of Washington, Seattle, WA, USA
| | - Margo Werner
- Department of Immunology, University of Washington, Seattle, WA, USA
| | - Jessica M Snyder
- Department of Comparative Medicine, University of Washington, Seattle, WA, USA
| | - Katrina Lichauco
- Department of Immunology, University of Washington, Seattle, WA, USA
| | - Ram Savan
- Department of Immunology, University of Washington, Seattle, WA, USA
| | - Daniel B Stetson
- Department of Immunology, University of Washington, Seattle, WA, USA
| | - Andrew Oberst
- Department of Immunology, University of Washington, Seattle, WA, USA.
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44
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Di Giorgio E, Xodo LE. Endogenous Retroviruses (ERVs): Does RLR (RIG-I-Like Receptors)-MAVS Pathway Directly Control Senescence and Aging as a Consequence of ERV De-Repression? Front Immunol 2022; 13:917998. [PMID: 35757716 PMCID: PMC9218063 DOI: 10.3389/fimmu.2022.917998] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 05/18/2022] [Indexed: 11/13/2022] Open
Abstract
Bi-directional transcription of Human Endogenous Retroviruses (hERVs) is a common feature of autoimmunity, neurodegeneration and cancer. Higher rates of cancer incidence, neurodegeneration and autoimmunity but a lower prevalence of autoimmune diseases characterize elderly people. Although the re-expression of hERVs is commonly observed in different cellular models of senescence as a result of the loss of their epigenetic transcriptional silencing, the hERVs modulation during aging is more complex, with a peak of activation in the sixties and a decline in the nineties. What is clearly accepted, instead, is the impact of the re-activation of dormant hERV on the maintenance of stemness and tissue self-renewing properties. An innate cellular immunity system, based on the RLR-MAVS circuit, controls the degradation of dsRNAs arising from the transcription of hERV elements, similarly to what happens for the accumulation of cytoplasmic DNA leading to the activation of cGAS/STING pathway. While agonists and inhibitors of the cGAS-STING pathway are considered promising immunomodulatory molecules, the effect of the RLR-MAVS pathway on innate immunity is still largely based on correlations and not on causality. Here we review the most recent evidence regarding the activation of MDA5-RIG1-MAVS pathway as a result of hERV de-repression during aging, immunosenescence, cancer and autoimmunity. We will also deal with the epigenetic mechanisms controlling hERV repression and with the strategies that can be adopted to modulate hERV expression in a therapeutic perspective. Finally, we will discuss if the RLR-MAVS signalling pathway actively modulates physiological and pathological conditions or if it is passively activated by them.
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Affiliation(s)
- Eros Di Giorgio
- Laboratory of Biochemistry, Department of Medicine, University of Udine, Udine, Italy
| | - Luigi E Xodo
- Laboratory of Biochemistry, Department of Medicine, University of Udine, Udine, Italy
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45
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Yang Y, Sun Q, Guo J, Liu Z, Wang J, Yao Y, Yu P, Cao J, Zhang Y, Song X. Identification of a lncRNA AC011511.5- Mediated Competitive Endogenous RNA Network Involved in the Pathogenesis of Allergic Rhinitis. Front Genet 2022; 13:811679. [PMID: 35711945 PMCID: PMC9194448 DOI: 10.3389/fgene.2022.811679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 05/05/2022] [Indexed: 11/13/2022] Open
Abstract
LncRNA-miRNA-mRNA competing endogenous RNA (ceRNA) networks are thought to be involved in regulating the development of various inflammatory diseases. Up to now, the mechanism of such a network in allergic rhinitis (AR) remains unclear. In the study, we investigated the differential expression of lncRNAs (DElncRNAs) and mRNAs (DEmRNAs) by performing a microarray analysis of peripheral blood obtained from AR patients and healthy control subjects. StarBase 2.0 was used to predict miRNAs that might interact with various DElncRNAs and DEmRNAs. We constructed a ceRNA network based on potential lncRNA-miRNA-mRNA interactions. The Cluster Profiler R package was used to perform a functional enrichment analysis of the hub-ceRNA, and Molecular Complex Detection (MCODE) was used for further identification of the hub-ceRNA network. The expression levels of genes contained in the hub-ceRNA network were validated by RT-PCR. In total, 247 DEmRNAs and 18 DelncRNAs were aberrantly expressed in the PBMCs of AR patients. A ceRNA network consisting of 3 lncRNAs, 45 miRNAs, and 75 mRNAs was constructed. A GO analysis showed that negative regulation of immune response, response to interferon-beta, and response to interferon-alpha were important terms. A KEGG pathway analysis showed that 75 mRNAs were significantly enriched in "NOD-like receptor signaling pathway" and "tryptophan metabolism". Ultimately, a hub-ceRNA network was constructed based on 1 lncRNA (AC011511.5), 5 miRNAs (hsa-miR-576-5p, hsa-miR-520c-5p, hsa-miR-519b-5p, hsa-miR-519c-5p, and hsa-miR-518d-5p), and 2 mRNAs (ZFP36L1 and SNX27). Following further verification, we found that overexpression of lncRNA AC011511.5 or inhibitor of miR-576-5p upregulated SNX27 expression. The expression of SNX27 in the lncRNA AC011511.5 overexpression & miR-576-5p inhibitor group was not different from that in the miR-576-5p inhibitor group or lncRNA AC011511.5 overexpression group, indicating that overexpression of lncRNA AC011511.5 could not further upregulate the expression of SNX27 in miR-576-5p inhibitor Jurkat cells. This network may provide new insights to search for biomarkers that can be used for the diagnosis and clinical treatment of AR.
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Affiliation(s)
- Yujuan Yang
- Department of Otorhinolaryngology, Head and Neck Surgery, Yantai Yuhuangding Hospital, Qingdao University, Yantai, China.,Shandong Provincial Clinical Research Center for Otorhinolaryngologic Diseases, Yantai, China
| | - Qi Sun
- Department of Otorhinolaryngology, Head and Neck Surgery, Yantai Yuhuangding Hospital, Qingdao University, Yantai, China.,Shandong Provincial Clinical Research Center for Otorhinolaryngologic Diseases, Yantai, China
| | - Jing Guo
- Department of Otorhinolaryngology, Head and Neck Surgery, Yantai Yuhuangding Hospital, Qingdao University, Yantai, China.,Shandong Provincial Clinical Research Center for Otorhinolaryngologic Diseases, Yantai, China
| | - Zhen Liu
- Department of Otorhinolaryngology, Head and Neck Surgery, Yantai Yuhuangding Hospital, Qingdao University, Yantai, China.,Shandong Provincial Clinical Research Center for Otorhinolaryngologic Diseases, Yantai, China
| | - Jianwei Wang
- Department of Otorhinolaryngology, Head and Neck Surgery, Yantai Yuhuangding Hospital, Qingdao University, Yantai, China.,Shandong Provincial Clinical Research Center for Otorhinolaryngologic Diseases, Yantai, China
| | - Yao Yao
- Department of Otorhinolaryngology, Head and Neck Surgery, Yantai Yuhuangding Hospital, Qingdao University, Yantai, China.,Shandong Provincial Clinical Research Center for Otorhinolaryngologic Diseases, Yantai, China
| | - Pengyi Yu
- Department of Otorhinolaryngology, Head and Neck Surgery, Yantai Yuhuangding Hospital, Qingdao University, Yantai, China.,Shandong Provincial Clinical Research Center for Otorhinolaryngologic Diseases, Yantai, China
| | - Jiayu Cao
- Department of Otorhinolaryngology, Head and Neck Surgery, Yantai Yuhuangding Hospital, Qingdao University, Yantai, China.,Shandong Provincial Clinical Research Center for Otorhinolaryngologic Diseases, Yantai, China
| | - Yu Zhang
- Department of Otorhinolaryngology, Head and Neck Surgery, Yantai Yuhuangding Hospital, Qingdao University, Yantai, China.,Shandong Provincial Clinical Research Center for Otorhinolaryngologic Diseases, Yantai, China
| | - Xicheng Song
- Department of Otorhinolaryngology, Head and Neck Surgery, Yantai Yuhuangding Hospital, Qingdao University, Yantai, China.,Shandong Provincial Clinical Research Center for Otorhinolaryngologic Diseases, Yantai, China
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46
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Yang R, Yu S, Xu T, Zhang J, Wu S. Emerging role of RNA sensors in tumor microenvironment and immunotherapy. J Hematol Oncol 2022; 15:43. [PMID: 35413927 PMCID: PMC9006576 DOI: 10.1186/s13045-022-01261-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Accepted: 04/01/2022] [Indexed: 12/16/2022] Open
Abstract
RNA sensors detect foreign and endogenous RNAs to protect the host by initiating innate and adaptive immune response. In tumor microenvironment (TME), activation of RNA sensors induces tumor-inhibitory cytotoxic T lymphocyte responses and inhibits the activity of immunosuppressive cells though stimulating type I IFN signaling pathway. These characteristics allow RNA sensors to be prospective targets in tumor immunotherapy. Therefore, a comprehensive understanding of the roles of RNA sensors in TME could provide new insight into the antitumor immunotherapy. Moreover, RNA sensors could be prominent triggering targets to synergize with immunotherapies. In this review, we highlight the diverse mechanisms of RNA sensors in cancer immunity and their emerging contributions in cancer immunotherapy, including monotherapy with RNA sensor agonists, as well as combination with chemotherapy, radiotherapy, immune checkpoint blockade or cancer vaccine.
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Affiliation(s)
- Rui Yang
- Department of Obstetrics and Gynecology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Sihui Yu
- Department of Obstetrics and Gynecology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Tianhan Xu
- Department of Obstetrics and Gynecology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Jiawen Zhang
- Department of Obstetrics and Gynecology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China. .,Reproductive Medicine Center, Department of Obstetrics and Gynecology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China.
| | - Sufang Wu
- Department of Obstetrics and Gynecology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China.
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Tassinari V, Cerboni C, Soriani A. Self or Non-Self? It Is also a Matter of RNA Recognition and Editing by ADAR1. BIOLOGY 2022; 11:biology11040568. [PMID: 35453767 PMCID: PMC9024829 DOI: 10.3390/biology11040568] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 04/01/2022] [Accepted: 04/06/2022] [Indexed: 01/19/2023]
Abstract
Simple Summary A fundamental feature of innate immune cells is to detect the presence of non-self, such as potentially harmful nucleic acids, by germline-encoded specialized receptors called pattern recognition receptors (PRRs). ADAR1 is one key enzyme avoiding aberrant type I interferon (IFN-I) production and immune cell activation by the conversion of adenosine to inosine (A-to-I) in double-stranded RNA (dsRNA) structures that arise in self mRNA containing specific repetitive elements. This review intends to give an up-to-date and detailed overview of the ADAR1-mediated ability to modulate the immune response in autoimmune diseases and cancer progression. Abstract A-to-I editing is a post-transcriptional mechanism affecting coding and non-coding dsRNAs, catalyzed by the adenosine deaminases acting on the RNA (ADAR) family of enzymes. A-to-I modifications of endogenous dsRNA (mainly derived from Alu repetitive elements) prevent their recognition by cellular dsRNA sensors, thus avoiding the induction of antiviral signaling and uncontrolled IFN-I production. This process, mediated by ADAR1 activity, ensures the activation of an innate immune response against foreign (non-self) but not self nucleic acids. As a consequence, ADAR1 mutations or its de-regulated activity promote the development of autoimmune diseases and strongly impact cell growth, also leading to cancer. Moreover, the excessive inflammation promoted by Adar1 ablation also impacts T and B cell maturation, as well as the development of dendritic cell subsets, revealing a new role of ADAR1 in the homeostasis of the immune system.
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48
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Chan CP, Jin DY. Cytoplasmic RNA sensors and their interplay with RNA-binding partners in innate antiviral response: theme and variations. RNA (NEW YORK, N.Y.) 2022; 28:449-477. [PMID: 35031583 PMCID: PMC8925969 DOI: 10.1261/rna.079016.121] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Sensing of pathogen-associated molecular patterns including viral RNA by innate immunity represents the first line of defense against viral infection. In addition to RIG-I-like receptors and NOD-like receptors, several other RNA sensors are known to mediate innate antiviral response in the cytoplasm. Double-stranded RNA-binding protein PACT interacts with prototypic RNA sensor RIG-I to facilitate its recognition of viral RNA and induction of host interferon response, but variations of this theme are seen when the functions of RNA sensors are modulated by other RNA-binding proteins to impinge on antiviral defense, proinflammatory cytokine production and cell death programs. Their discrete and coordinated actions are crucial to protect the host from infection. In this review, we will focus on cytoplasmic RNA sensors with an emphasis on their interplay with RNA-binding partners. Classical sensors such as RIG-I will be briefly reviewed. More attention will be brought to new insights on how RNA-binding partners of RNA sensors modulate innate RNA sensing and how viruses perturb the functions of RNA-binding partners.
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Affiliation(s)
- Chi-Ping Chan
- School of Biomedical Sciences and State Key Laboratory of Liver Research, Faculty of Medicine Building, Pokfulam, Hong Kong
| | - Dong-Yan Jin
- School of Biomedical Sciences and State Key Laboratory of Liver Research, Faculty of Medicine Building, Pokfulam, Hong Kong
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49
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Stok JE, Oosenbrug T, ter Haar LR, Gravekamp D, Bromley CP, Zelenay S, Reis e Sousa C, van der Veen AG. RNA sensing via the RIG-I-like receptor LGP2 is essential for the induction of a type I IFN response in ADAR1 deficiency. EMBO J 2022; 41:e109760. [PMID: 35156720 PMCID: PMC8922249 DOI: 10.15252/embj.2021109760] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 01/07/2022] [Accepted: 01/11/2022] [Indexed: 12/12/2022] Open
Abstract
RNA editing by the adenosine deaminase ADAR1 prevents innate immune responses to endogenous RNAs. In ADAR1-deficient cells, unedited self RNAs form base-paired structures that resemble viral RNAs and inadvertently activate the cytosolic RIG-I-like receptor (RLR) MDA5, leading to an antiviral type I interferon (IFN) response. Mutations in ADAR1 cause Aicardi-Goutières Syndrome (AGS), an autoinflammatory syndrome characterized by chronic type I IFN production. Conversely, ADAR1 loss and the consequent type I IFN production restricts tumor growth and potentiates the activity of some chemotherapeutics. Here, we show that another RIG-I-like receptor, LGP2, also has an essential role in the induction of a type I IFN response in ADAR1-deficient human cells. This requires the canonical function of LGP2 as an RNA sensor and facilitator of MDA5-dependent signaling. Furthermore, we show that the sensitivity of tumor cells to ADAR1 loss requires LGP2 expression. Finally, type I IFN induction in tumor cells depleted of ADAR1 and treated with some chemotherapeutics fully depends on LGP2 expression. These findings highlight a central role for LGP2 in self RNA sensing with important clinical implications.
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Affiliation(s)
- Jorn E Stok
- Department of ImmunologyLeiden University Medical CentreLeidenThe Netherlands
| | - Timo Oosenbrug
- Department of ImmunologyLeiden University Medical CentreLeidenThe Netherlands
| | - Laurens R ter Haar
- Department of ImmunologyLeiden University Medical CentreLeidenThe Netherlands
| | - Dennis Gravekamp
- Department of ImmunologyLeiden University Medical CentreLeidenThe Netherlands
| | - Christian P Bromley
- Cancer Research UK Manchester InstituteThe University of ManchesterAlderley ParkUK
| | - Santiago Zelenay
- Cancer Research UK Manchester InstituteThe University of ManchesterAlderley ParkUK
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Abstract
As brutally demonstrated by the COVID-19 pandemic, an effective immune system is essential for survival. Developed over evolutionary time, viral nucleic acid detection is a central pillar in the defensive armamentarium used to combat foreign microbial invasion. To ensure cellular homeostasis, such a strategy necessitates the efficient discrimination of pathogen-derived DNA and RNA from that of the host. In 2011, it was suggested that an upregulation of type I interferon signalling might serve as a defining feature of a novel set of Mendelian inborn errors of immunity, where antiviral sensors are triggered by host nucleic acids due to a failure of self versus non-self discrimination. These rare disorders have played a surprisingly significant role in informing our understanding of innate immunity and the relevance of type I interferon signalling for human health and disease. Here we consider what we have learned in this time, and how the field may develop in the future.
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Affiliation(s)
- Yanick J. Crow
- grid.4305.20000 0004 1936 7988MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, UK ,grid.508487.60000 0004 7885 7602Laboratory of Neurogenetics and Neuroinflammation, Institut Imagine, Université de Paris, Paris, France
| | - Daniel B. Stetson
- grid.34477.330000000122986657Department of Immunology, University of Washington School of Medicine, Seattle, WA USA
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