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Zhang Y, Wang K, Zhao Z, Sun S, Zhang K, Huang R, Zeng F, Hu H. ADAR3 expression is an independent prognostic factor in lower-grade diffuse gliomas and positively correlated with the editing level of GRIA2 Q607R. Cancer Cell Int 2018; 18:196. [PMID: 30524204 PMCID: PMC6276233 DOI: 10.1186/s12935-018-0695-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Accepted: 11/27/2018] [Indexed: 02/06/2023] Open
Abstract
Background RNA editing by adenosine deaminases acting on RNA (ADARs) converts adenosines to inosines (A-to-I) in RNA, that alters gene expression and generates protein diversity. Dysregulation of A-to-I editing has been found associated with a number of nervous system diseases. However, the role of ADAR3, a brain specific high expression adenosine deaminase, in gliomas has rarely been investigated. In this study we illuminated the clinical significance and molecular features of ADAR3 in patients with glioma. Methods 309 glioma samples from Chinese Glioma Genome Atlas were enrolled into this study. In validation sets, 601 glioma samples in TCGA, 410 glioma samples in REMBRANDT and 258 glioma samples in GSE16011 were obtained. Relationships between ADAR3 expression and prognosis-related genomic alteration, outcome and gene ontology analysis were investigated. Moreover, the characteristic of GRIA2Q607R editing in gliomas has been investigated. Graphpad Prism 5.0, SPSS 16.0 and R language were used to perform statistical analysis and graphical work. Results ADAR3 expression was down regulated along with glioma grade progression in CGGA dataset. ADAR3 was characteristically highly expressed in neural subtype and IDH1/2 mutant preference. Moreover, high expression of ADAR3 predicted a better prognosis in lower-grade glioma (LGG) patients and multivariate analysis suggested ADAR3 expression was an independent prognostic indicator. The results of the three other validation datasets showed similar findings. Bioinformatics analyses suggested that ADAR3 may play a role in the malignant transformation of glioma cells by affecting cell proliferation, angiogenesis or cell adhesion. Furthermore, the editing level of GRIA2Q607R was significantly correlated with ADAR3 expression. Conclusions Our study demonstrated the clinical and molecular characterization of ADAR3 in glioma development and progression. ADAR3 expression was negatively associated with tumor malignant in the overall glioma patients. And it was a favorable independent prognostic indicator of LGG patients. ADAR3 appeared to act as a tumor suppressor in glioma cells. Therefore, ADAR3 represented a potential therapeutic target and useful prognostic factor for glioma patients.
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Affiliation(s)
- Ying Zhang
- 1Department of Molecular Neuropathology, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China.,Chinese Glioma Cooperative Group (CGCG), Beijing, China.,3Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.,4Department of Radiotherapy, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Kuanyu Wang
- 1Department of Molecular Neuropathology, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China.,Chinese Glioma Cooperative Group (CGCG), Beijing, China.,3Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.,4Department of Radiotherapy, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Zheng Zhao
- 1Department of Molecular Neuropathology, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China.,Chinese Glioma Cooperative Group (CGCG), Beijing, China.,3Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.,4Department of Radiotherapy, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Si Sun
- 1Department of Molecular Neuropathology, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China.,Chinese Glioma Cooperative Group (CGCG), Beijing, China.,3Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.,4Department of Radiotherapy, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Kenan Zhang
- 1Department of Molecular Neuropathology, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China.,Chinese Glioma Cooperative Group (CGCG), Beijing, China.,3Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.,4Department of Radiotherapy, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Ruoyu Huang
- 1Department of Molecular Neuropathology, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China.,Chinese Glioma Cooperative Group (CGCG), Beijing, China.,3Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.,4Department of Radiotherapy, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Fan Zeng
- 1Department of Molecular Neuropathology, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China.,Chinese Glioma Cooperative Group (CGCG), Beijing, China.,3Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.,4Department of Radiotherapy, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Huimin Hu
- 1Department of Molecular Neuropathology, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China.,Chinese Glioma Cooperative Group (CGCG), Beijing, China.,3Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.,4Department of Radiotherapy, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
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152
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Pfaller CK, Donohue RC, Nersisyan S, Brodsky L, Cattaneo R. Extensive editing of cellular and viral double-stranded RNA structures accounts for innate immunity suppression and the proviral activity of ADAR1p150. PLoS Biol 2018; 16:e2006577. [PMID: 30496178 PMCID: PMC6264153 DOI: 10.1371/journal.pbio.2006577] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 10/26/2018] [Indexed: 01/09/2023] Open
Abstract
The interferon (IFN)-mediated innate immune response is the first line of defense against viruses. However, an IFN-stimulated gene, the adenosine deaminase acting on RNA 1 (ADAR1), favors the replication of several viruses. ADAR1 binds double-stranded RNA and converts adenosine to inosine by deamination. This form of editing makes duplex RNA unstable, thereby preventing IFN induction. To better understand how ADAR1 works at the cellular level, we generated cell lines that express exclusively either the IFN-inducible, cytoplasmic isoform ADAR1p150, the constitutively expressed nuclear isoform ADAR1p110, or no isoform. By comparing the transcriptome of these cell lines, we identified more than 150 polymerase II transcripts that are extensively edited, and we attributed most editing events to ADAR1p150. Editing is focused on inverted transposable elements, located mainly within introns and untranslated regions, and predicted to form duplex RNA structures. Editing of these elements occurs also in primary human samples, and there is evidence for cross-species evolutionary conservation of editing patterns in primates and, to a lesser extent, in rodents. Whereas ADAR1p150 rarely edits tightly encapsidated standard measles virus (MeV) genomes, it efficiently edits genomes with inverted repeats accidentally generated by a mutant MeV. We also show that immune activation occurs in fully ADAR1-deficient (ADAR1KO) cells, restricting virus growth, and that complementation of these cells with ADAR1p150 rescues virus growth and suppresses innate immunity activation. Finally, by knocking out either protein kinase R (PKR) or mitochondrial antiviral signaling protein (MAVS)—another protein controlling the response to duplex RNA—in ADAR1KO cells, we show that PKR activation elicits a stronger antiviral response. Thus, ADAR1 prevents innate immunity activation by cellular transcripts that include extensive duplex RNA structures. The trade-off is that viruses take advantage of ADAR1 to elude innate immunity control. The innate immune response is a double-edged sword. It must protect the host from pathogens while avoiding accidental recognition of “self” molecular patterns, which can lead to autoimmune reactions. Double-stranded RNA is among the most potent inducers of cellular stress and interferon responses. We characterize here a mechanism that prevents autoimmune activation and show that an RNA virus, measles virus, can exploit it to elude innate immune responses. This mechanism relies on the enzyme adenosine deaminase acting on RNA 1 (ADAR1), which converts adenosine residues within duplex RNA structures to inosine. We identify duplex RNA structures in the 3′ untranslated regions of over 150 cellular transcripts and show that they are heavily edited in ADAR1-expressing cells. We detect the same type of editing in duplex RNA–forming defective genomes accidentally generated by measles virus. Loss of RNA editing causes strong innate immune responses and is detrimental to viral replication. Thus, by keeping the amount of duplex RNA in cells below an immune activation threshold, ADAR1 prevents autoimmunity while also favoring pathogens.
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Affiliation(s)
- Christian K. Pfaller
- Department of Molecular Medicine, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Ryan C. Donohue
- Department of Molecular Medicine, Mayo Clinic, Rochester, Minnesota, United States of America
- Mayo Clinic Graduate School of Biomedical Sciences, Rochester, Minnesota, United States of America
| | - Stepan Nersisyan
- Tauber Bioinformatics Research Center, University of Haifa, Haifa, Israel
- Lomonosov Moscow State University, Moscow, Russia
| | - Leonid Brodsky
- Tauber Bioinformatics Research Center, University of Haifa, Haifa, Israel
| | - Roberto Cattaneo
- Department of Molecular Medicine, Mayo Clinic, Rochester, Minnesota, United States of America
- Mayo Clinic Graduate School of Biomedical Sciences, Rochester, Minnesota, United States of America
- * E-mail:
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153
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Jinnah H, Ulbricht RJ. Using mouse models to unlock the secrets of non-synonymous RNA editing. Methods 2018; 156:40-45. [PMID: 30827465 DOI: 10.1016/j.ymeth.2018.10.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 10/05/2018] [Accepted: 10/22/2018] [Indexed: 11/26/2022] Open
Abstract
The deamination of adenosine to inosine by RNA editing is a widespread post-transcriptional process that expands genetic diversity. Selective substitution of inosine for adenosine in pre-mRNA transcripts can alter splicing, mRNA stability, and the amino acid sequence of the encoded protein. The functional consequences of RNA editing-dependent amino acid substitution are known for only a handful of RNA editing substrates. Many of these studies began in heterologous mammalian expression systems; however, the gold-standard for determining the functional significance of transcript-specific re-coding A-to-I editing events is the generation of a mouse model that expresses only one RNA editing-dependent isoform. The frequency of site-specific RNA editing varies spatially, temporally, and in some diseases, therefore, determining the profile of RNA editing frequency is also an important element of research. Here we review the strengths and weaknesses of existing mouse models for the study of RNA editing, as well as methods for quantifying RNA editing frequencies in vivo. Importantly, we highlight opportunities for future RNA editing studies in mice, projecting that improvements in genome editing and high-throughput sequencing technologies will allow the field to excel in coming years.
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Affiliation(s)
- Hussain Jinnah
- Vanderbilt University, Department of Pharmacology, 8140 Medical Research Building 3, Nashville, TN 37240-1104, United States.
| | - Randi J Ulbricht
- Missouri State University, Department of Biomedical Sciences, 901 South National Avenue, Springfield, MO 65897, United States.
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154
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Nakahama T, Kato Y, Kim JI, Vongpipatana T, Suzuki Y, Walkley CR, Kawahara Y. ADAR1-mediated RNA editing is required for thymic self-tolerance and inhibition of autoimmunity. EMBO Rep 2018; 19:embr.201846303. [PMID: 30361393 DOI: 10.15252/embr.201846303] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 09/21/2018] [Accepted: 09/28/2018] [Indexed: 12/13/2022] Open
Abstract
T cells play a crucial role in the adaptive immune system, and their maturation process is tightly regulated. Adenosine deaminase acting on RNA 1 (ADAR1) is the enzyme responsible for adenosine-to-inosine RNA editing in dsRNAs, and loss of ADAR1 activates the innate immune sensing response via melanoma differentiation-associated protein 5 (MDA5), which interprets unedited dsRNA as non-self. Although ADAR1 is highly expressed in the thymus, its role in the adaptive immune system, especially in T cells, remains elusive. Here, we demonstrate that T cell-specific deletion of Adar1 in mice causes abnormal thymic T cell maturation including impaired negative selection and autoimmunity such as spontaneous colitis. This is caused by excessive expression of interferon-stimulated genes, which reduces T cell receptor (TCR) signal transduction, due to a failure of RNA editing in ADAR1-deficient thymocytes. Intriguingly, concurrent deletion of MDA5 restores thymocyte maturation and prevents colitis. These findings suggest that prevention of MDA5 sensing of endogenous dsRNA by ADAR1-mediated RNA editing is required for preventing both innate immune responses and T cell-mediated autoimmunity.
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Affiliation(s)
- Taisuke Nakahama
- Department of RNA Biology and Neuroscience, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Yuki Kato
- Department of RNA Biology and Neuroscience, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Jung In Kim
- Department of RNA Biology and Neuroscience, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Tuangtong Vongpipatana
- Department of RNA Biology and Neuroscience, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Yutaka Suzuki
- Laboratory of Systems Genomics, Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, Japan
| | - Carl R Walkley
- St Vincent's Institute and Department of Medicine, St. Vincent's Hospital, University of Melbourne, Fitzroy, Vic., Australia
| | - Yukio Kawahara
- Department of RNA Biology and Neuroscience, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
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155
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Gatsiou A, Vlachogiannis N, Lunella FF, Sachse M, Stellos K. Adenosine-to-Inosine RNA Editing in Health and Disease. Antioxid Redox Signal 2018; 29:846-863. [PMID: 28762759 DOI: 10.1089/ars.2017.7295] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
SIGNIFICANCE Adenosine deamination in transcriptome results in the formation of inosine, a process that is called A-to-I RNA editing. Adenosine deamination is one of the more than 140 described RNA modifications. A-to-I RNA editing is catalyzed by adenosine deaminase acting on RNA (ADAR) enzymes and is essential for life. Recent Advances: Accumulating evidence supports a critical role of RNA editing in all aspects of RNA metabolism, including mRNA stability, splicing, nuclear export, and localization, as well as in recoding of proteins. These advances have significantly enhanced the understanding of mechanisms involved in development and in homeostasis. Furthermore, recent studies have indicated that RNA editing may be critically involved in cancer, aging, neurological, autoimmune, or cardiovascular diseases. CRITICAL ISSUES This review summarizes recent and significant achievements in the field of A-to-I RNA editing and discusses the importance and translational value of this RNA modification for gene expression, cellular, and organ function, as well as for disease development. FUTURE DIRECTIONS Elucidation of the exact RNA editing-dependent mechanisms in a single-nucleotide level may pave the path toward the development of novel therapeutic strategies focusing on modulation of ADAR function in the disease context. Antioxid. Redox Signal. 29, 846-863.
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Affiliation(s)
- Aikaterini Gatsiou
- 1 Institute of Cardiovascular Regeneration, Center of Molecular Medicine, JW Goethe University Frankfurt , Frankfurt, Germany .,2 Department of Biosciences, JW Goethe University Frankfurt , Frankfurt, Germany .,3 Department of Cardiology, Center of Internal Medicine, JW Goethe University Frankfurt , Frankfurt, Germany .,4 German Center of Cardiovascular Research (DZHK) , Rhein-Main Partner Site, Frankfurt, Germany
| | - Nikolaos Vlachogiannis
- 5 Rheumatology Unit, First Department of Propaedeutic Internal Medicine and Joint Rheumatology Academic Program, School of Medicine, National and Kapodistrian University of Athens , Athens, Greece
| | - Federica Francesca Lunella
- 1 Institute of Cardiovascular Regeneration, Center of Molecular Medicine, JW Goethe University Frankfurt , Frankfurt, Germany .,2 Department of Biosciences, JW Goethe University Frankfurt , Frankfurt, Germany .,3 Department of Cardiology, Center of Internal Medicine, JW Goethe University Frankfurt , Frankfurt, Germany .,4 German Center of Cardiovascular Research (DZHK) , Rhein-Main Partner Site, Frankfurt, Germany
| | - Marco Sachse
- 1 Institute of Cardiovascular Regeneration, Center of Molecular Medicine, JW Goethe University Frankfurt , Frankfurt, Germany .,3 Department of Cardiology, Center of Internal Medicine, JW Goethe University Frankfurt , Frankfurt, Germany .,4 German Center of Cardiovascular Research (DZHK) , Rhein-Main Partner Site, Frankfurt, Germany
| | - Konstantinos Stellos
- 1 Institute of Cardiovascular Regeneration, Center of Molecular Medicine, JW Goethe University Frankfurt , Frankfurt, Germany .,3 Department of Cardiology, Center of Internal Medicine, JW Goethe University Frankfurt , Frankfurt, Germany .,4 German Center of Cardiovascular Research (DZHK) , Rhein-Main Partner Site, Frankfurt, Germany
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156
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John D, Weirick T, Dimmeler S, Uchida S. RNAEditor: easy detection of RNA editing events and the introduction of editing islands. Brief Bioinform 2018; 18:993-1001. [PMID: 27694136 DOI: 10.1093/bib/bbw087] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2016] [Indexed: 12/30/2022] Open
Abstract
RNA editing of adenosine residues to inosine ('A-to-I editing') is the most common RNA modification event detectible with RNA sequencing (RNA-seq). While not directly detectable, inosine is read by next-generation sequencers as guanine. Therefore, mapping RNA-seq reads to their corresponding reference genome can detect potential editing events by identifying 'A-to-G' conversions. However, one must exercise caution when searching for editing sites, as A-to-G conversions also arise from sequencing errors as well as mutations. To address these complexities, several algorithms and software products have been developed to accurately identify editing events. Here, we survey currently available methods to analyze RNA editing events and introduce a new easy-to-use bioinformatics tool 'RNAEditor' for the detection of RNA editing events. During the development of RNAEditor, we noticed editing often happened in clusters, which we named 'editing islands'. We developed a clustering algorithm to find editing islands and included it in RNAEditor. RNAEditor is freely available at http://rnaeditor.uni-frankfurt.de. We anticipate that RNAEditor will provide biologists with an easy-to-use tool for studying RNA editing events and the newly defined editing islands.
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157
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Gogoi M, Shreenivas MM, Chakravortty D. Hoodwinking the Big-Eater to Prosper: The Salmonella-Macrophage Paradigm. J Innate Immun 2018; 11:289-299. [PMID: 30041182 DOI: 10.1159/000490953] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 06/10/2018] [Indexed: 12/12/2022] Open
Abstract
Salmonella is a major cause of morbidity and mortality in the developing and underdeveloped nations. Being a foodborne disease, Salmonella infection is primarily contracted through the ingestion of contaminated food or water, or due to close contact with infected/carrier individuals. It is an intracellular pathogen, which can survive and replicate in various cells including macrophages, dendritic cells, epithelial cells, and other white blood cells. Once Salmonella crosses the intestinal barrier, it disseminates to various systemic sites by circulation via immune cells. One of the major cell types which are involved in Salmonella infection are host macrophages. They are the niche for intracellular survival and proliferation of Salmonella and a mode of dissemination to distal systemic sites. These cells are very crucial as they mediate the mounting of an appropriate innate and adaptive anti-Salmonella immune response. In this review, we have tried to concise the current knowledge of complex interactions that occur between Salmonella and macrophages.
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Affiliation(s)
- Mayuri Gogoi
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India.,Division of Biological Sciences, Indian Institute of Science, Bangalore, India
| | - Meghanashree M Shreenivas
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India.,Undergraduate Studies, Indian Institute of Science, Bangalore, India
| | - Dipshikha Chakravortty
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India, .,Division of Biological Sciences, Indian Institute of Science, Bangalore, India, .,Centre for Biosystems Science and Engineering, Indian Institute of Science, Bangalore, India,
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158
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Wang TT, Li ZG, Wang Q. The RNA-Specific Adenosine Deaminase ADAR1 Inhibits Human Protein Kinase R Activation. Viral Immunol 2018; 31:537-538. [PMID: 29883277 DOI: 10.1089/vim.2018.0056] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Tony T Wang
- 1 Center for Infectious Diseases , SRI International, Harrisonburg, Virginia
| | - Z Galvin Li
- 1 Center for Infectious Diseases , SRI International, Harrisonburg, Virginia
| | - Qingde Wang
- 2 Department of Surgery, University of Pittsburgh Medical Center , Pittsburgh, Pennsylvania
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159
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Yu W, Xu H, Xue Y, An D, Li H, Chen W, Yu D, Sun Y, Ma J, Tang Y, Xiao Z, Yin S. 5-HT 2CR antagonist/5-HT 2CR inverse agonist recovered the increased isolation-induced aggressive behavior of BALB/c mice mediated by ADAR1 (p110) expression and Htr2c RNA editing. Brain Behav 2018; 8:e00929. [PMID: 29541541 PMCID: PMC5840448 DOI: 10.1002/brb3.929] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
INTRODUCTION Social isolation enhances the aggressive behavior of animals, but the detailed mechanism remains unclear. Epigenetic studies have suggested that Htr2c RNA editing is closely related to aggressive behavior. This study aims to obtain a fundamental understanding of how social isolation impacts adenosine deaminase acting on RNA 1 (ADAR1, RNA editing enzyme) and Htr2c RNA editing, leading to aggressive behavior, and explore the effective solutions for the recovery of this behavior. METHODS We evaluated 21-day-old BALB/c mice with and without isolation for aggressive behavior using a resident-intruder test. Immune-reactivity and protein expression of ADAR1 (p110) were measured using immunohistochemistry and Western blotting. Htr2c RNA editing was evaluated using pyrosequencing. In addition, the 5-HT 2C R antagonist SB243213/5-HT 2C R inverse agonist SB206553 was used to treat the isolated mice, and the performance of both treatments on the behavior, ADAR1 (p110) expression, and Htr2c RNA editing in isolated mice was examined. RESULTS Both the protein expression and immune-reactivity of ADAR1 (p110) in the amygdala decreased, but the percentage of Htr2c RNA editing at A and B sites of amygdala only showed a moderate increase in isolated BALB/c mice with enhanced aggressive behavior compared to the age-matched group-housed BALB/c mice. Additionally, treatment with the 5-HT 2C R antagonist SB243213/5-HT 2C R inverse agonist SB206553 recovered the enhanced aggressive behavior of isolated mice and returned the protein expression and immune-reactivity of ADAR1 (p110) back to the normal level. Moreover, compared to the age-matched isolated mice treated with physiological saline, isolated mice treated with 5-HT 2C R inverse agonist SB206553 showed a lower percentage of Htr2c RNA editing at both A and B sites, and the same result occurred in isolated mice treated with 5-HT 2C R antagonist SB243213 at B site of Htr2c RNA editing. CONCLUSIONS The 5-HT 2C R antagonist SB243213/5-HT 2C R inverse agonist SB206553 recovered increased aggressive behavior of isolated BALB/c mice mediated by ADAR1 (p110) expression and Htr2c RNA editing.
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Affiliation(s)
- Weizhi Yu
- College of Basic Medical Sciences Dalian Medical University Dalian China
| | - Hong Xu
- College of Basic Medical Sciences Dalian Medical University Dalian China
| | - Ying Xue
- College of Basic Medical Sciences Dalian Medical University Dalian China
| | - Dong An
- College of Basic Medical Sciences Dalian Medical University Dalian China
| | - Huairui Li
- The 2nd Affiliated Hospital Dalian Medical University Dalian China
| | - Wei Chen
- College of Basic Medical Sciences Dalian Medical University Dalian China
| | - Deqin Yu
- College of Basic Medical Sciences Dalian Medical University Dalian China
| | - Yiping Sun
- College of Basic Medical Sciences Dalian Medical University Dalian China
| | - Jianmei Ma
- College of Basic Medical Sciences Dalian Medical University Dalian China
| | - Yiyuan Tang
- Texas Tech Neuroimaging Institute Texas Tech University Lubbock TX USA
| | - Zhaoyang Xiao
- The 2nd Affiliated Hospital Dalian Medical University Dalian China
| | - Shengming Yin
- College of Basic Medical Sciences Dalian Medical University Dalian China
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160
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Chung H, Calis JJA, Wu X, Sun T, Yu Y, Sarbanes SL, Dao Thi VL, Shilvock AR, Hoffmann HH, Rosenberg BR, Rice CM. Human ADAR1 Prevents Endogenous RNA from Triggering Translational Shutdown. Cell 2018; 172:811-824.e14. [PMID: 29395325 DOI: 10.1016/j.cell.2017.12.038] [Citation(s) in RCA: 344] [Impact Index Per Article: 57.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Revised: 10/30/2017] [Accepted: 12/27/2017] [Indexed: 01/12/2023]
Abstract
Type I interferon (IFN) is produced when host sensors detect foreign nucleic acids, but how sensors differentiate self from nonself nucleic acids, such as double-stranded RNA (dsRNA), is incompletely understood. Mutations in ADAR1, an adenosine-to-inosine editing enzyme of dsRNA, cause Aicardi-Goutières syndrome, an autoinflammatory disorder associated with spontaneous interferon production and neurologic sequelae. We generated ADAR1 knockout human cells to explore ADAR1 substrates and function. ADAR1 primarily edited Alu elements in RNA polymerase II (pol II)-transcribed mRNAs, but not putative pol III-transcribed Alus. During the IFN response, ADAR1 blocked translational shutdown by inhibiting hyperactivation of PKR, a dsRNA sensor. ADAR1 dsRNA binding and catalytic activities were required to fully prevent endogenous RNA from activating PKR. Remarkably, ADAR1 knockout neuronal progenitor cells exhibited MDA5 (dsRNA sensor)-dependent spontaneous interferon production, PKR activation, and cell death. Thus, human ADAR1 regulates sensing of self versus nonself RNA, allowing pathogen detection while avoiding autoinflammation.
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Affiliation(s)
- Hachung Chung
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065, USA
| | - Jorg J A Calis
- Program in Immunogenomics, The Rockefeller University, New York, NY 10065, USA
| | - Xianfang Wu
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065, USA
| | - Tony Sun
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065, USA
| | - Yingpu Yu
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065, USA
| | - Stephanie L Sarbanes
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065, USA
| | - Viet Loan Dao Thi
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065, USA
| | - Abigail R Shilvock
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065, USA
| | - H-Heinrich Hoffmann
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065, USA
| | - Brad R Rosenberg
- Program in Immunogenomics, The Rockefeller University, New York, NY 10065, USA; Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Charles M Rice
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065, USA.
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161
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Zaidan H, Ramaswami G, Golumbic YN, Sher N, Malik A, Barak M, Galiani D, Dekel N, Li JB, Gaisler-Salomon I. A-to-I RNA editing in the rat brain is age-dependent, region-specific and sensitive to environmental stress across generations. BMC Genomics 2018; 19:28. [PMID: 29310578 PMCID: PMC5759210 DOI: 10.1186/s12864-017-4409-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2017] [Accepted: 12/21/2017] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Adenosine-to-inosine (A-to-I) RNA editing is an epigenetic modification catalyzed by adenosine deaminases acting on RNA (ADARs), and is especially prevalent in the brain. We used the highly accurate microfluidics-based multiplex PCR sequencing (mmPCR-seq) technique to assess the effects of development and environmental stress on A-to-I editing at 146 pre-selected, conserved sites in the rat prefrontal cortex and amygdala. Furthermore, we asked whether changes in editing can be observed in offspring of stress-exposed rats. In parallel, we assessed changes in ADARs expression levels. RESULTS In agreement with previous studies, we found editing to be generally higher in adult compared to neonatal rat brain. At birth, editing was generally lower in prefrontal cortex than in amygdala. Stress affected editing at the serotonin receptor 2c (Htr2c), and editing at this site was significantly altered in offspring of rats exposed to prereproductive stress across two generations. Stress-induced changes in Htr2c editing measured with mmPCR-seq were comparable to changes measured with Sanger and Illumina sequencing. Developmental and stress-induced changes in Adar and Adarb1 mRNA expression were observed but did not correlate with editing changes. CONCLUSIONS Our findings indicate that mmPCR-seq can accurately detect A-to-I RNA editing in rat brain samples, and confirm previous accounts of a developmental increase in RNA editing rates. Our findings also point to stress in adolescence as an environmental factor that alters RNA editing patterns several generations forward, joining a growing body of literature describing the transgenerational effects of stress.
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Affiliation(s)
- Hiba Zaidan
- Department of Psychology, University of Haifa, Haifa, Israel
| | - Gokul Ramaswami
- Department of Genetics, Stanford University, Stanford, CA, USA.,Program in Neurogenetics, Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, California, Los Angeles, USA
| | - Yaela N Golumbic
- Faculty of Education in Technology and Science, Technion, Haifa, Israel.,Faculty of Civil and Environmental Engineering, Technion, Haifa, Israel
| | - Noa Sher
- Bioinformatics Core Unit, University of Haifa, Haifa, Israel
| | - Assaf Malik
- Bioinformatics Core Unit, University of Haifa, Haifa, Israel.,Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel
| | - Michal Barak
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Dalia Galiani
- Department of Biological Regulation, The Weizmann Institute of Science, Rehovot, Israel
| | - Nava Dekel
- Department of Biological Regulation, The Weizmann Institute of Science, Rehovot, Israel
| | - Jin B Li
- Department of Genetics, Stanford University, Stanford, CA, USA
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162
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Abstract
The molecular process of RNA editing allows changes in RNA transcripts that increase genomic diversity. These highly conserved RNA editing events are catalyzed by a group of enzymes known as adenosine deaminases acting on double-stranded RNA (ADARs). ADARs are necessary for normal development, they bind to over thousands of genes, impact millions of editing sites, and target critical components of the central nervous system (CNS) such as glutamate receptors, serotonin receptors, and potassium channels. Dysfunctional ADARs are known to cause alterations in CNS protein products and therefore play a role in chronic or acute neurodegenerative and psychiatric diseases as well as CNS cancer. Here, we review how RNA editing deficiency impacts CNS function and summarize its role during disease pathogenesis.
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Affiliation(s)
- Ileana Lorenzini
- Barrow Neurological Institute, Department of Neurobiology, Dignity Health, St. Joseph's Hospital and Medical Center, Phoenix, AZ, USA
| | - Stephen Moore
- Barrow Neurological Institute, Department of Neurobiology, Dignity Health, St. Joseph's Hospital and Medical Center, Phoenix, AZ, USA
- Interdisciplinary Graduate Program in Neuroscience, Arizona State University, Tempe, AZ, USA
| | - Rita Sattler
- Department of Neurobiology and Neurology, Dignityhealth St. Joseph's Hospital, Barrow Neurological Institute, Phoenix, AZ, USA.
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163
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Abstract
RNA editing is a posttranscriptional modification process that alters the sequence of RNA molecules. RNA editing is related to many human diseases. However, the identification of RNA editing sites typically requires matched genomic sequence or multiple related expression data sets. Here we describe the GIREMI tool (genome-independent identification of RNA editing by mutual information; https://github.com/zhqingit/giremi ) that is designed to accurately and sensitively predict adenosine-to-inosine editing from a single RNA-Seq data set.
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Affiliation(s)
- Qing Zhang
- Integrative Biology and Physiology, The University of California, Los Angeles (UCLA), Los Angeles, CA, USA.
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164
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Nakano M, Nakajima M. Significance of A-to-I RNA editing of transcripts modulating pharmacokinetics and pharmacodynamics. Pharmacol Ther 2018; 181:13-21. [DOI: 10.1016/j.pharmthera.2017.07.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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165
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Azad MTA, Bhakta S, Tsukahara T. Site-directed RNA editing by adenosine deaminase acting on RNA for correction of the genetic code in gene therapy. Gene Ther 2017; 24:779-786. [PMID: 28984845 DOI: 10.1038/gt.2017.90] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 09/26/2017] [Accepted: 09/29/2017] [Indexed: 12/11/2022]
Abstract
Site-directed RNA editing is an important technique for correcting gene sequences and ultimately tuning protein function. In this study, we engineered the deaminase domain of adenosine deaminase acting on RNA (ADAR1) and the MS2 system to target-specific adenosines, with the goal of correcting G-to-A mutations at the RNA level. For this purpose, the ADAR1 deaminase domain was fused downstream of the RNA-binding protein MS2, which has affinity for the MS2 RNA. To direct editing to specific targets, we designed guide RNAs complementary to target RNAs. The guide RNAs directed the ADAR1 deaminase to the desired editing site, where it converted adenosine to inosine. To provide proof of principle, we used an allele of enhanced green fluorescent protein (EGFP) bearing a mutation at the 58th amino acid (TGG), encoding Trp, into an amber (TAG) or ochre (TAA) stop codon. In HEK-293 cells, our system could convert stop codons to read-through codons, thereby turning on fluorescence. We confirmed the specificity of editing at the DNA level by restriction fragment length polymorphism analysis and sequencing, and at the protein level by western blotting. The editing efficiency of this enzyme system was ~5%. We believe that this system could be used to treat genetic diseases resulting from G-to-A point mutations.
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Affiliation(s)
- Md T A Azad
- School of Materials Science, Japan Advanced Institute of Science and Technology, Ishikawa, Japan
- Department of Veterinary and Animal Sciences, Faculty of Agriculture, University of Rajshahi, Rajshahi-6205, Bangladesh
| | - S Bhakta
- School of Materials Science, Japan Advanced Institute of Science and Technology, Ishikawa, Japan
| | - T Tsukahara
- School of Materials Science, Japan Advanced Institute of Science and Technology, Ishikawa, Japan
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166
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Tang ZL, Wang S, Tu C, Wang T, Ma CW, Liu Y, Xiao SX, Wang XP. Eight Novel Mutations of the ADAR1 Gene in Chinese Patients with Dyschromatosis Symmetrica Hereditaria. Genet Test Mol Biomarkers 2017; 22:104-108. [PMID: 29185800 PMCID: PMC5806071 DOI: 10.1089/gtmb.2017.0207] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
AIMS To identify potential novel gene mutations in Chinese patients with dyschromatosis symmetrica hereditaria (DSH). METHODS We enrolled 8 Chinese patients with familial DSH, 5 Chinese patients with sporadic DSH, and 100 randomly selected healthy individuals in this study. The genome of each participant was extracted from peripheral blood samples. Sanger sequencing of the ADAR1 gene was performed after polymerase chain reaction amplifications. Comparisons between the DNA sequences of the affected individuals and the NCBI database were performed. RESULTS We detected eight novel heterozygous mutations and five previously reported mutations in the ADAR1 gene in our patients. The novel mutations include c.1934 + 3A>G, c.2749A>G, c.2311insA, c.3233G>A, c.3019 + 1G>T, c.2894C>A, c.1202_1205del, and c.2280C>A. These detected novel mutations are predicted to induce two frame-shift mutations, one nonsense mutation, three missense mutations, and two splice-site mutations. CONCLUSIONS The findings of this study expand our knowledge of the range of ADAR1 gene mutations in DSH and will contribute to identifying correlations between the various DSH phenotypes and genotypes. Furthermore, they may provide insight into the underlying pathogenic mechanism.
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Affiliation(s)
- Zhuang-Li Tang
- 1 Department of Dermatology and Venereology, the Second Affiliated Hospital of Xi'an Jiaotong University , Xi'an, Shaanxi, People's Republic of China
| | - Shuang Wang
- 1 Department of Dermatology and Venereology, the Second Affiliated Hospital of Xi'an Jiaotong University , Xi'an, Shaanxi, People's Republic of China
| | - Chen Tu
- 1 Department of Dermatology and Venereology, the Second Affiliated Hospital of Xi'an Jiaotong University , Xi'an, Shaanxi, People's Republic of China
| | - Tian Wang
- 1 Department of Dermatology and Venereology, the Second Affiliated Hospital of Xi'an Jiaotong University , Xi'an, Shaanxi, People's Republic of China
| | - Cheng-Wen Ma
- 2 Department of General Surgery, the Second Affiliated Hospital of Xi'an Jiaotong University , Xi'an, Shaanxi, People's Republic of China
| | - Yan Liu
- 1 Department of Dermatology and Venereology, the Second Affiliated Hospital of Xi'an Jiaotong University , Xi'an, Shaanxi, People's Republic of China
| | - Sheng-Xiang Xiao
- 1 Department of Dermatology and Venereology, the Second Affiliated Hospital of Xi'an Jiaotong University , Xi'an, Shaanxi, People's Republic of China
| | - Xiao-Peng Wang
- 1 Department of Dermatology and Venereology, the Second Affiliated Hospital of Xi'an Jiaotong University , Xi'an, Shaanxi, People's Republic of China
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167
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Snyder EM, Licht K, Braun RE. Testicular adenosine to inosine RNA editing in the mouse is mediated by ADARB1. Biol Reprod 2017; 96:244-253. [PMID: 28395340 DOI: 10.1095/biolreprod.116.145151] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 11/28/2016] [Indexed: 11/01/2022] Open
Abstract
Adenosine to inosine (A-to-I) RNA editing occurs in a wide range of tissues and cell types and can be catalyzed by one of the two adenosine deaminase acting on double-stranded RNA enzymes, ADAR and ADARB1. Editing can impact both coding and noncoding regions of RNA, and in higher organisms has been proposed to function in adaptive evolution. Neither the prevalence of A-to-I editing nor the role of either ADAR or ADARB1 has been examined in the context of germ cell development in mammals. Computational analysis of whole testis and cell-type specific RNA-sequencing data followed by molecular confirmation demonstrated that A-to-I RNA editing occurs in both the germ line and in somatic Sertoli cells in two targets, Cog3 and Rpa1. Expression analysis demonstrated both Adar and Adarb1 were expressed in both Sertoli cells and in a cell-type dependent manner during germ cell development. Conditional ablation of Adar did not impact testicular RNA editing in either germ cells or Sertoli cells. Additionally, Adar ablation in either cell type did not have gross impacts on germ cell development or male fertility. In contrast, global Adarb1 knockout animals demonstrated a complete loss of A-to-I RNA editing in spite of normal germ cell development. Taken together, these observations demonstrate ADARB1 mediates A-to-I RNA editing in the testis and these editing events are dispensable for male fertility in an inbred mouse strain in the lab.
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Affiliation(s)
| | - Konstantin Licht
- Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
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168
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Fritzell K, Xu LD, Lagergren J, Öhman M. ADARs and editing: The role of A-to-I RNA modification in cancer progression. Semin Cell Dev Biol 2017; 79:123-130. [PMID: 29146145 DOI: 10.1016/j.semcdb.2017.11.018] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 11/08/2017] [Accepted: 11/12/2017] [Indexed: 11/17/2022]
Abstract
Cancer arises when pathways that control cell functions such as proliferation and migration are dysregulated to such an extent that cells start to divide uncontrollably and eventually spread throughout the body, ultimately endangering the survival of an affected individual. It is well established that somatic mutations are important in cancer initiation and progression as well as in creation of tumor diversity. Now also modifications of the transcriptome are emerging as a significant force during the transition from normal cell to malignant tumor. Editing of adenosine (A) to inosine (I) in double-stranded RNA, catalyzed by adenosine deaminases acting on RNA (ADARs), is one dynamic modification that in a combinatorial manner can give rise to a very diverse transcriptome. Since the cell interprets inosine as guanosine (G), editing can result in non-synonymous codon changes in transcripts as well as yield alternative splicing, but also affect targeting and disrupt maturation of microRNA. ADAR editing is essential for survival in mammals but its dysregulation can lead to cancer. ADAR1 is for instance overexpressed in, e.g., lung cancer, liver cancer, esophageal cancer and chronic myoelogenous leukemia, which with few exceptions promotes cancer progression. In contrast, ADAR2 is lowly expressed in e.g. glioblastoma, where the lower levels of ADAR2 editing leads to malignant phenotypes. Altogether, RNA editing by the ADAR enzymes is a powerful regulatory mechanism during tumorigenesis. Depending on the cell type, cancer progression seems to mainly be induced by ADAR1 upregulation or ADAR2 downregulation, although in a few cases ADAR1 is instead downregulated. In this review, we discuss how aberrant editing of specific substrates contributes to malignancy.
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Affiliation(s)
- Kajsa Fritzell
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, 106 91, Stockholm, Sweden
| | - Li-Di Xu
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, 106 91, Stockholm, Sweden
| | - Jens Lagergren
- School of Computer Science and Communication, Science for Life Laboratory (SciLifeLab), Royal Institute of Technology (KTH), Stockholm, Sweden
| | - Marie Öhman
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, 106 91, Stockholm, Sweden.
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169
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RNA editing by ADAR1 leads to context-dependent transcriptome-wide changes in RNA secondary structure. Nat Commun 2017; 8:1440. [PMID: 29129909 PMCID: PMC5682290 DOI: 10.1038/s41467-017-01458-8] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 09/19/2017] [Indexed: 11/09/2022] Open
Abstract
Adenosine deaminase acting on RNA 1 (ADAR1) is the master RNA editor, catalyzing the deamination of adenosine to inosine. RNA editing is vital for preventing abnormal activation of cytosolic nucleic acid sensing pathways by self-double-stranded RNAs. Here we determine, by parallel analysis of RNA secondary structure sequencing (PARS-seq), the global RNA secondary structure changes in ADAR1 deficient cells. Surprisingly, ADAR1 silencing resulted in a lower global double-stranded to single-stranded RNA ratio, suggesting that A-to-I editing can stabilize a large subset of imperfect RNA duplexes. The duplexes destabilized by editing are composed of vastly complementary inverted Alus found in untranslated regions of genes performing vital biological processes, including housekeeping functions and type-I interferon responses. They are predominantly cytoplasmic and generally demonstrate higher ribosomal occupancy. Our findings imply that the editing effect on RNA secondary structure is context dependent and underline the intricate regulatory role of ADAR1 on global RNA secondary structure.
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170
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Abstract
One of the most prevalent forms of post-transcritpional RNA modification is the conversion of adenosine nucleosides to inosine (A-to-I), mediated by the ADAR family of enzymes. The functional requirement and regulatory landscape for the majority of A-to-I editing events are, at present, uncertain. Recent studies have identified key in vivo functions of ADAR enzymes, informing our understanding of the biological importance of A-to-I editing. Large-scale studies have revealed how editing is regulated both in cis and in trans. This review will explore these recent studies and how they broaden our understanding of the functions and regulation of ADAR-mediated RNA editing.
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Affiliation(s)
- Carl R Walkley
- St Vincent's Institute of Medical Research, Fitzroy, Victoria, 3065, Australia. .,Department of Medicine, St Vincent's Hospital, University of Melbourne, Fitzroy, Victoria, 3065, Australia.
| | - Jin Billy Li
- Department of Genetics, Stanford University, Stanford, CA, 94305, USA.
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171
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Petre J, Lasseaux E, Ged C, Arveiler B, Taïeb A, Morice-Picard F. ADAR1splicing mutation leading to dyschromatosis hereditaria in a Caucasian patient. J Eur Acad Dermatol Venereol 2017; 32:e79-e80. [DOI: 10.1111/jdv.14530] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- J. Petre
- CHU de Bordeaux; Service de Dermatologie; Centre de Référence des Maladies Rares de la Peau Bordeaux; F-33076 France
| | - E. Lasseaux
- CHU de Bordeaux; Service de Génétique Médicale; Bordeaux F-33076 France
| | - C. Ged
- CHU de Bordeaux; Service de Dermatologie; Centre de Référence des Maladies Rares de la Peau Bordeaux; F-33076 France
- CHU de Bordeaux; Service de Biochimie; Bordeaux F-33076 France
| | - B. Arveiler
- CHU de Bordeaux; Service de Génétique Médicale; Bordeaux F-33076 France
| | - A. Taïeb
- CHU de Bordeaux; Service de Dermatologie; Centre de Référence des Maladies Rares de la Peau Bordeaux; F-33076 France
| | - F. Morice-Picard
- CHU de Bordeaux; Service de Dermatologie; Centre de Référence des Maladies Rares de la Peau Bordeaux; F-33076 France
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172
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Ganem NS, Ben-Asher N, Lamm AT. In cancer, A-to-I RNA editing can be the driver, the passenger, or the mechanic. Drug Resist Updat 2017; 32:16-22. [PMID: 29145975 DOI: 10.1016/j.drup.2017.09.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
In recent years, A-to-I RNA modifications performed by the Adenosine Deaminase Acting on RNA (ADAR) protein family were found to be expressed at altered levels in multiple human malignancies. A-to-I RNA editing changes adenosine to inosine on double stranded RNA, thereby changing transcript sequence and structure. Although A-to-I RNA editing have the potential to change essential mRNA transcripts, affecting their corresponding protein structures, most of the human editing sites identified to date reside in non-coding repetitive transcripts such as Alu elements. Therefore, the impact of the hypo- or hyper-editing found in specific cancers remains unknown. Moreover, it is yet unclear whether or not changes in RNA editing and ADAR expression levels facilitate or even drive cancer progression or are just a byproduct of other affected pathways. In both cases, however, the levels of RNA editing and ADAR enzymes can possibly be used as specific biomarkers, as their levels change differently in specific malignancies. More significantly, recent studies suggest that ADAR enzymes can be used to reverse the oncogenic process, suggesting a potential for gene therapies. This review focuses on new findings that suggest that RNA editing by ADARs can affect cancer progression and even formation. We also discuss new possibilities of using ADAR enzymes and RNA editing as cancer biomarkers, indicators of chemotherapeutic drug sensitivity, and even to be themselves potential therapeutic tools.
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Affiliation(s)
- Nabeel S Ganem
- Faculty of Biology, Technion - Israel Institute of Technology, Technion City, Haifa 32000, Israel
| | - Noa Ben-Asher
- Faculty of Biology, Technion - Israel Institute of Technology, Technion City, Haifa 32000, Israel
| | - Ayelet T Lamm
- Faculty of Biology, Technion - Israel Institute of Technology, Technion City, Haifa 32000, Israel.
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173
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Wang C, Zou J, Ma X, Wang E, Peng G. Mechanisms and implications of ADAR-mediated RNA editing in cancer. Cancer Lett 2017; 411:27-34. [PMID: 28974449 DOI: 10.1016/j.canlet.2017.09.036] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 09/20/2017] [Accepted: 09/21/2017] [Indexed: 12/11/2022]
Abstract
Adenosine deaminases acting on RNA (ADARs) are enzymes that catalyze the conversion of adenosine (A) to inosine (I) in double-stranded RNAs. Inosine exhibits similar properties as guanosine. As a result, A-to-I editing has a great impact on edited RNAs, not only affecting the base pairing properties, but also altering codons after translation. A-to-I editing are known to mediate and diversify transcripts. However, the overall biological effect of ADARs are still largely unknown. Aberrant ADAR activity and editing dysregulation are present in a variety of cancers, including hepatocellular carcinoma, chronic myelogenous leukemia, glioblastoma and melanoma. ADAR-mediated A-to-I editing can influence uncontrolled nucleotide changes, resulting in susceptibility of cells to developmental defects and potential carcinogenicity. A deeper understanding of the biological function of ADARs may provide mechanistic insights in the development of new cancer therapy. Here, we discuss recent advances in research on ADAR in detail including the structure and function of ADARs, the biochemistry of ADAR-mediated RNA editing, and the relevance of ADAR proteins in cancer.
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Affiliation(s)
- Chen Wang
- Department of Oncology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Jun Zou
- Department of Oncology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Xiangyi Ma
- Department of Obstetrics and Gynecology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Edward Wang
- OncoMed Pharmaceuticals, Redwood City, CA 94063, USA
| | - Guang Peng
- Department of Clinical Cancer Prevention, MD Anderson Cancer Center, The University of Texas, Houston, TX 77030, USA.
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174
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Licht K, Jantsch MF. The Other Face of an Editor: ADAR1 Functions in Editing-Independent Ways. Bioessays 2017; 39. [DOI: 10.1002/bies.201700129] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 08/29/2017] [Indexed: 02/04/2023]
Affiliation(s)
- Konstantin Licht
- Department of Cell and Developmental Biology Center for Anatomy and Cell Biology; Medical University of Vienna; Schwarzspanierstrasse 17 A-1090 Vienna Austria
| | - Michael F. Jantsch
- Department of Cell and Developmental Biology Center for Anatomy and Cell Biology; Medical University of Vienna; Schwarzspanierstrasse 17 A-1090 Vienna Austria
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175
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Gallo A, Vukic D, Michalík D, O’Connell MA, Keegan LP. ADAR RNA editing in human disease; more to it than meets the I. Hum Genet 2017; 136:1265-1278. [DOI: 10.1007/s00439-017-1837-0] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 08/22/2017] [Indexed: 01/08/2023]
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176
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Protein recoding by ADAR1-mediated RNA editing is not essential for normal development and homeostasis. Genome Biol 2017; 18:166. [PMID: 28874170 PMCID: PMC5585977 DOI: 10.1186/s13059-017-1301-4] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 08/15/2017] [Indexed: 02/07/2023] Open
Abstract
Background Adenosine-to-inosine (A-to-I) editing of dsRNA by ADAR proteins is a pervasive epitranscriptome feature. Tens of thousands of A-to-I editing events are defined in the mouse, yet the functional impact of most is unknown. Editing causing protein recoding is the essential function of ADAR2, but an essential role for recoding by ADAR1 has not been demonstrated. ADAR1 has been proposed to have editing-dependent and editing-independent functions. The relative contribution of these in vivo has not been clearly defined. A critical function of ADAR1 is editing of endogenous RNA to prevent activation of the dsRNA sensor MDA5 (Ifih1). Outside of this, how ADAR1 editing contributes to normal development and homeostasis is uncertain. Results We describe the consequences of ADAR1 editing deficiency on murine homeostasis. Adar1E861A/E861AIfih1-/- mice are strikingly normal, including their lifespan. There is a mild, non-pathogenic innate immune activation signature in the Adar1E861A/E861AIfih1-/- mice. Assessing A-to-I editing across adult tissues demonstrates that outside of the brain, ADAR1 performs the majority of editing and that ADAR2 cannot compensate in its absence. Direct comparison of the Adar1-/- and Adar1E861A/E861A alleles demonstrates a high degree of concordance on both Ifih1+/+ and Ifih1-/- backgrounds, suggesting no substantial contribution from ADAR1 editing-independent functions. Conclusions These analyses demonstrate that the lifetime absence of ADAR1-editing is well tolerated in the absence of MDA5. We conclude that protein recoding arising from ADAR1-mediated editing is not essential for organismal homeostasis. Additionally, the phenotypes associated with loss of ADAR1 are the result of RNA editing and MDA5-dependent functions. Electronic supplementary material The online version of this article (doi:10.1186/s13059-017-1301-4) contains supplementary material, which is available to authorized users.
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177
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ADAR1-mediated 3' UTR editing and expression control of antiapoptosis genes fine-tunes cellular apoptosis response. Cell Death Dis 2017; 8:e2833. [PMID: 28542129 PMCID: PMC5520689 DOI: 10.1038/cddis.2017.12] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 12/19/2016] [Accepted: 12/20/2016] [Indexed: 12/12/2022]
Abstract
Adenosine-to-inosine RNA editing constitutes a crucial component of the cellular transcriptome and critically underpins organism survival and development. While recent high-throughput approaches have provided comprehensive documentation of the RNA editome, its functional output remains mostly unresolved, particularly for events in the non-coding regions. Gene ontology analysis of the known RNA editing targets unveiled a preponderance of genes related to apoptosis regulation, among which proto-oncogenes XIAP and MDM2 encode two the most abundantly edited transcripts. To further decode this potential functional connection, here we showed that the main RNA editor ADAR1 directly targets this 3′ UTR editing of XIAP and MDM2, and further exerts a negative regulation on the expression of their protein products. This post-transcriptional silencing role was mediated via the inverted Alu elements in the 3′ UTR but independent of alteration in transcript stability or miRNA targeting. Rather, we discovered that ADAR1 competes transcript occupancy with the RNA shuttling factor STAU1 to facilitate nuclear retention of the XIAP and MDM2 mRNAs. As a consequence, ADAR1 may acquire functionality in part by conferring spatial distribution and translation efficiency of the target transcripts. Finally, abrogation of ADAR1 expression or catalytic activity elicited a XIAP-dependent suppression of apoptotic response, whereas ectopic expression reversed this protective effect on cell death. Together, our results extended the known functions of ADAR1 and RNA editing to the critical fine-tuning of the intracellular apoptotic signaling and also provided mechanistic explanation for ADAR1’s roles in development and tumorigenesis.
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ADAR1 controls apoptosis of stressed cells by inhibiting Staufen1-mediated mRNA decay. Nat Struct Mol Biol 2017; 24:534-543. [PMID: 28436945 PMCID: PMC5461201 DOI: 10.1038/nsmb.3403] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 03/27/2017] [Indexed: 01/10/2023]
Abstract
Both p150 and p110 isoforms of ADAR1 convert adenosine to inosine in double-stranded RNA (dsRNA). ADAR1p150 suppresses the dsRNA sensing mechanism that activates MDA5-MAVS-IFN signaling in the cytoplasm. In contrast, the biological function of the ADAR1p110 isoform, usually located in the nucleus, remains largely unknown. Here we show that stress-activated phosphorylation of ADAR1p110 by MKK6-p38-MSK MAP kinases promotes its binding to Exportin-5 and export from the nucleus. Once translocated to the cytoplasm, ADAR1p110 suppresses apoptosis of stressed cells by protecting many anti-apoptotic gene transcripts that contain 3′UTR dsRNA structures primarily made from inverted Alu repeats. ADAR1p110 competitively inhibits binding of Staufen1 to the 3′UTR dsRNAs and antagonizes the Staufen1-mediated mRNA decay. Our studies revealed a new stress response mechanism, in which human ADAR1p110 and Staufen1 regulate surveillance of a set of mRNAs required for survival of stressed cells.
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179
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Abstract
Inosine is one of the most common modifications found in human RNAs and the Adenosine Deaminases that act on RNA (ADARs) are the main enzymes responsible for its production. ADARs were first discovered in the 1980s and since then our understanding of ADARs has advanced tremendously. For instance, it is now known that defective ADAR function can cause human diseases. Furthermore, recently solved crystal structures of the human ADAR2 deaminase bound to RNA have provided insights regarding the catalytic and substrate recognition mechanisms. In this chapter, we describe the occurrence of inosine in human RNAs and the newest perspective on the ADAR family of enzymes, including their substrate recognition, catalytic mechanism, regulation as well as the consequences of A-to-I editing, and their relation to human diseases.
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180
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ADAR1 and MicroRNA; A Hidden Crosstalk in Cancer. Int J Mol Sci 2017; 18:ijms18040799. [PMID: 28398248 PMCID: PMC5412383 DOI: 10.3390/ijms18040799] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Revised: 04/04/2017] [Accepted: 04/06/2017] [Indexed: 11/17/2022] Open
Abstract
The evolution of cancer cells is believed to be dependent on genetic or epigenetic alterations. However, this concept has recently been challenged by another mode of nucleotide alteration, RNA editing, which is frequently up-regulated in cancer. RNA editing is a biochemical process in which either Adenosine or Cytosine is deaminated by a group of RNA editing enzymes including ADAR (Adenosine deaminase; RNA specific) or APOBEC3B (Apolipoprotein B mRNA Editing Enzyme Catalytic Subunit 3B). The result of RNA editing is usually adenosine to inosine (A-to-I) or cytidine to uridine (C-to-U) transition, which can affect protein coding, RNA stability, splicing and microRNA-target interactions. The functional impact of these alterations is largely unclear and is a subject of extensive research. In the present review, we will specifically focus on the influence of ADARs on carcinogenesis via the regulation of microRNA processing and functioning. This follows a brief review of the current knowledge of properties of ADAR enzyme, RNA editing, and microRNA processing.
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181
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Li Y, Banerjee S, Goldstein SA, Dong B, Gaughan C, Rath S, Donovan J, Korennykh A, Silverman RH, Weiss SR. Ribonuclease L mediates the cell-lethal phenotype of double-stranded RNA editing enzyme ADAR1 deficiency in a human cell line. eLife 2017; 6. [PMID: 28362255 PMCID: PMC5404912 DOI: 10.7554/elife.25687] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 03/30/2017] [Indexed: 12/13/2022] Open
Abstract
ADAR1 isoforms are adenosine deaminases that edit and destabilize double-stranded RNA reducing its immunostimulatory activities. Mutation of ADAR1 leads to a severe neurodevelopmental and inflammatory disease of children, Aicardi-Goutiéres syndrome. In mice, Adar1 mutations are embryonic lethal but are rescued by mutation of the Mda5 or Mavs genes, which function in IFN induction. However, the specific IFN regulated proteins responsible for the pathogenic effects of ADAR1 mutation are unknown. We show that the cell-lethal phenotype of ADAR1 deletion in human lung adenocarcinoma A549 cells is rescued by CRISPR/Cas9 mutagenesis of the RNASEL gene or by expression of the RNase L antagonist, murine coronavirus NS2 accessory protein. Our result demonstrate that ablation of RNase L activity promotes survival of ADAR1 deficient cells even in the presence of MDA5 and MAVS, suggesting that the RNase L system is the primary sensor pathway for endogenous dsRNA that leads to cell death. DOI:http://dx.doi.org/10.7554/eLife.25687.001
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Affiliation(s)
- Yize Li
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Shuvojit Banerjee
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, United States
| | - Stephen A Goldstein
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Beihua Dong
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, United States
| | - Christina Gaughan
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, United States
| | - Sneha Rath
- Department of Molecular Biology, Princeton University, Princeton, United States
| | - Jesse Donovan
- Department of Molecular Biology, Princeton University, Princeton, United States
| | - Alexei Korennykh
- Department of Molecular Biology, Princeton University, Princeton, United States
| | - Robert H Silverman
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, United States
| | - Susan R Weiss
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
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182
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Abstract
Adenosine deaminases acting on RNA (ADARs) are zinc-containing enzymes that deaminate adenosine bases to inosines within dsRNA regions in transcripts. In short, structured dsRNA hairpins individual adenosine bases may be targeted specifically and edited with up to one hundred percent efficiency, leading to the production of alternative protein variants. However, the majority of editing events occur within longer stretches of dsRNA formed by pairing of repetitive sequences. Here, many different adenosine bases are potential targets but editing efficiency is usually much lower. Recent work shows that ADAR-mediated RNA editing is also required to prevent aberrant activation of antiviral innate immune sensors that detect viral dsRNA in the cytoplasm. Missense mutations in the ADAR1 RNA editing enzyme cause a fatal auto-inflammatory disease, Aicardi–Goutières syndrome (AGS) in affected children. In addition RNA editing by ADARs has been observed to increase in many cancers and also can contribute to vascular disease. Thus the role of RNA editing in the progression of various diseases can no longer be ignored. The ability of ADARs to alter the sequence of RNAs has also been used to artificially target model RNAs in vitro and in cells for RNA editing. Potentially this approach may be used to repair genetic defects and to alter genetic information at the RNA level. In this review we focus on the role of ADARs in disease development and progression and on their potential use to artificially modify RNAs in a targeted manner.
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Affiliation(s)
- Prajakta Bajad
- a Medical University of Vienna, Center of Anatomy and Cell Biology , Department of Cell- and Developmental Biology , Schwarzspanierstrasse, Vienna , Austria
| | - Michael F Jantsch
- a Medical University of Vienna, Center of Anatomy and Cell Biology , Department of Cell- and Developmental Biology , Schwarzspanierstrasse, Vienna , Austria
| | - Liam Keegan
- b CEITEC at Masaryk University , Kamenice, Czech Republic
| | - Mary O'Connell
- b CEITEC at Masaryk University , Kamenice, Czech Republic
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183
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Wettengel J, Reautschnig P, Geisler S, Kahle PJ, Stafforst T. Harnessing human ADAR2 for RNA repair - Recoding a PINK1 mutation rescues mitophagy. Nucleic Acids Res 2017; 45:2797-2808. [PMID: 27907896 PMCID: PMC5389476 DOI: 10.1093/nar/gkw911] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 09/27/2016] [Accepted: 09/30/2016] [Indexed: 02/06/2023] Open
Abstract
Site-directed A-to-I RNA editing is a technology for re-programming genetic information at the RNA-level. We describe here the first design of genetically encodable guideRNAs that enable the re-addressing of human ADAR2 toward specific sites in user-defined mRNA targets. Up to 65% editing yield has been achieved in cell culture for the recoding of a premature Stop codon (UAG) into tryptophan (UIG). In the targeted gene, editing was very specific. We applied the technology to recode a recessive loss-of-function mutation in PINK1 (W437X) in HeLa cells and showed functional rescue of PINK1/Parkin-mediated mitophagy, which is linked to the etiology of Parkinson's disease. In contrast to other editing strategies, this approach requires no artificial protein. Our novel guideRNAs may allow for the development of a platform technology that requires only the administration or expression of a guideRNA to recode genetic information, with high potential for application in biology and medicine.
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Affiliation(s)
- Jacqueline Wettengel
- Interfaculty Institute of Biochemistry, University of Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany
| | - Philipp Reautschnig
- Interfaculty Institute of Biochemistry, University of Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany
| | - Sven Geisler
- Department for Neurodegenerative Diseases, Hertie Institute for Clinical Brain Research, University of Tübingen, Otfried-Müller-Strasse 27, 72076 Tübingen, Germany
- German Center for Neurodegenerative Diseases, Otfried-Müller-Strasse 23, 72076 Tübingen, Germany
| | - Philipp J. Kahle
- Department for Neurodegenerative Diseases, Hertie Institute for Clinical Brain Research, University of Tübingen, Otfried-Müller-Strasse 27, 72076 Tübingen, Germany
- German Center for Neurodegenerative Diseases, Otfried-Müller-Strasse 23, 72076 Tübingen, Germany
| | - Thorsten Stafforst
- Interfaculty Institute of Biochemistry, University of Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany
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184
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Galipon J, Ishii R, Suzuki Y, Tomita M, Ui-Tei K. Differential Binding of Three Major Human ADAR Isoforms to Coding and Long Non-Coding Transcripts. Genes (Basel) 2017; 8:genes8020068. [PMID: 28208661 PMCID: PMC5333057 DOI: 10.3390/genes8020068] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Revised: 02/03/2017] [Accepted: 02/06/2017] [Indexed: 11/16/2022] Open
Abstract
RNA editing by deamination of adenosine to inosine is an evolutionarily conserved process involved in many cellular pathways, from alternative splicing to miRNA targeting. In humans, it is carried out by no less than three major adenosine deaminases acting on RNA (ADARs): ADAR1-p150, ADAR1-p110, and ADAR2. However, the first two derive from alternative splicing, so that it is currently impossible to delete ADAR1-p110 without also knocking out ADAR1-p150 expression. Furthermore, the expression levels of ADARs varies wildly among cell types, and no study has systematically explored the effect of each of these isoforms on the cell transcriptome. In this study, RNA immunoprecipitation (RIP)-sequencing on overexpressed ADAR isoforms tagged with green fluorescent protein (GFP) shows that each ADAR is associated with a specific set of differentially expressed genes, and that they each bind to distinct set of RNA targets. Our results show a good overlap with known edited transcripts, establishing RIP-seq as a valid method for the investigation of RNA editing biology.
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Affiliation(s)
- Josephine Galipon
- Keio University Institute for Advanced Biosciences, Tsuruoka 997-0017, Japan.
| | - Rintaro Ishii
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8562, Japan.
| | - Yutaka Suzuki
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8562, Japan.
| | - Masaru Tomita
- Keio University Institute for Advanced Biosciences, Tsuruoka 997-0017, Japan.
| | - Kumiko Ui-Tei
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8562, Japan.
- Graduate School of Science, The University of Tokyo, Tokyo 113-0032, Japan.
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185
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Oakes E, Anderson A, Cohen-Gadol A, Hundley HA. Adenosine Deaminase That Acts on RNA 3 (ADAR3) Binding to Glutamate Receptor Subunit B Pre-mRNA Inhibits RNA Editing in Glioblastoma. J Biol Chem 2017; 292:4326-4335. [PMID: 28167531 DOI: 10.1074/jbc.m117.779868] [Citation(s) in RCA: 124] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 02/05/2017] [Indexed: 01/08/2023] Open
Abstract
RNA editing is a cellular process that precisely alters nucleotide sequences, thus regulating gene expression and generating protein diversity. Over 60% of human transcripts undergo adenosine to inosine RNA editing, and editing is required for normal development and proper neuronal function of animals. Editing of one adenosine in the transcript encoding the glutamate receptor subunit B, glutamate receptor ionotropic AMPA 2 (GRIA2), modifies a codon, replacing the genomically encoded glutamine (Q) with arginine (R); thus this editing site is referred to as the Q/R site. Editing at the Q/R site of GRIA2 is essential, and reduced editing of GRIA2 transcripts has been observed in patients suffering from glioblastoma. In glioblastoma, incorporation of unedited GRIA2 subunits leads to a calcium-permeable glutamate receptor, which can promote cell migration and tumor invasion. In this study, we identify adenosine deaminase that acts on RNA 3 (ADAR3) as an important regulator of Q/R site editing, investigate its mode of action, and detect elevated ADAR3 expression in glioblastoma tumors compared with adjacent brain tissue. Overexpression of ADAR3 in astrocyte and astrocytoma cell lines inhibits RNA editing at the Q/R site of GRIA2 Furthermore, the double-stranded RNA binding domains of ADAR3 are required for repression of RNA editing. As the Q/R site of GRIA2 is specifically edited by ADAR2, we suggest that ADAR3 directly competes with ADAR2 for binding to GRIA2 transcript, inhibiting RNA editing, as evidenced by the direct binding of ADAR3 to the GRIA2 pre-mRNA. Finally, we provide evidence that both ADAR2 and ADAR3 expression contributes to the relative level of GRIA2 editing in tumors from patients suffering from glioblastoma.
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Affiliation(s)
| | - Ashley Anderson
- Medical Sciences Program, Indiana University, Bloomington, Indiana 47405 and
| | - Aaron Cohen-Gadol
- Department of Neurological Surgery, Goodman Campbell Brain and Spine, Indianapolis, Indiana 46202
| | - Heather A Hundley
- Medical Sciences Program, Indiana University, Bloomington, Indiana 47405 and
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186
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RNA Editing, ADAR1, and the Innate Immune Response. Genes (Basel) 2017; 8:genes8010041. [PMID: 28106799 PMCID: PMC5295035 DOI: 10.3390/genes8010041] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 01/03/2017] [Accepted: 01/11/2017] [Indexed: 01/14/2023] Open
Abstract
RNA editing, particularly A-to-I RNA editing, has been shown to play an essential role in mammalian embryonic development and tissue homeostasis, and is implicated in the pathogenesis of many diseases including skin pigmentation disorder, autoimmune and inflammatory tissue injury, neuron degeneration, and various malignancies. A-to-I RNA editing is carried out by a small group of enzymes, the adenosine deaminase acting on RNAs (ADARs). Only three members of this protein family, ADAR1-3, exist in mammalian cells. ADAR3 is a catalytically null enzyme and the most significant function of ADAR2 was found to be in editing on the neuron receptor GluR-B mRNA. ADAR1, however, has been shown to play more significant roles in biological and pathological conditions. Although there remains much that is not known about how ADAR1 regulates cellular function, recent findings point to regulation of the innate immune response as an important function of ADAR1. Without appropriate RNA editing by ADAR1, endogenous RNA transcripts stimulate cytosolic RNA sensing receptors and therefore activate the IFN-inducing signaling pathways. Overactivation of innate immune pathways can lead to tissue injury and dysfunction. However, obvious gaps in our knowledge persist as to how ADAR1 regulates innate immune responses through RNA editing. Here, we review critical findings from ADAR1 mechanistic studies focusing on its regulatory function in innate immune responses and identify some of the important unanswered questions in the field.
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187
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Heep M, Mach P, Reautschnig P, Wettengel J, Stafforst T. Applying Human ADAR1p110 and ADAR1p150 for Site-Directed RNA Editing-G/C Substitution Stabilizes GuideRNAs against Editing. Genes (Basel) 2017; 8:genes8010034. [PMID: 28098820 PMCID: PMC5295028 DOI: 10.3390/genes8010034] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Revised: 12/23/2016] [Accepted: 01/06/2017] [Indexed: 01/05/2023] Open
Abstract
Site-directed RNA editing is an approach to reprogram genetic information at the RNA level. We recently introduced a novel guideRNA that allows for the recruitment of human ADAR2 to manipulate genetic information. Here, we show that the current guideRNA design is already able to recruit another human deaminase, ADAR1, in both isoforms, p110 and p150. However, further optimization seems necessary as the current design is less efficient for ADAR1 isoforms. Furthermore, we describe hotspots at which the guideRNA itself is edited and show a way to circumvent this auto-editing without losing editing efficiency at the target. Both findings are important for the advancement of site-directed RNA editing as a tool in basic biology or as a platform for therapeutic editing.
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Affiliation(s)
- Madeleine Heep
- Interfaculty Institute of Biochemistry, University of Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany.
| | - Pia Mach
- Interfaculty Institute of Biochemistry, University of Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany.
| | - Philipp Reautschnig
- Interfaculty Institute of Biochemistry, University of Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany.
| | - Jacqueline Wettengel
- Interfaculty Institute of Biochemistry, University of Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany.
| | - Thorsten Stafforst
- Interfaculty Institute of Biochemistry, University of Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany.
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188
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Goldstein B, Agranat-Tamir L, Light D, Ben-Naim Zgayer O, Fishman A, Lamm AT. A-to-I RNA editing promotes developmental stage-specific gene and lncRNA expression. Genome Res 2016; 27:462-470. [PMID: 28031250 PMCID: PMC5340973 DOI: 10.1101/gr.211169.116] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 12/20/2016] [Indexed: 01/02/2023]
Abstract
A-to-I RNA editing is a conserved widespread phenomenon in which adenosine (A) is converted to inosine (I) by adenosine deaminases (ADARs) in double-stranded RNA regions, mainly noncoding. Mutations in ADAR enzymes in Caenorhabditis elegans cause defects in normal development but are not lethal as in human and mouse. Previous studies in C. elegans indicated competition between RNA interference (RNAi) and RNA editing mechanisms, based on the observation that worms that lack both mechanisms do not exhibit defects, in contrast to the developmental defects observed when only RNA editing is absent. To study the effects of RNA editing on gene expression and function, we established a novel screen that enabled us to identify thousands of RNA editing sites in nonrepetitive regions in the genome. These include dozens of genes that are edited at their 3′ UTR region. We found that these genes are mainly germline and neuronal genes, and that they are down-regulated in the absence of ADAR enzymes. Moreover, we discovered that almost half of these genes are edited in a developmental-specific manner, indicating that RNA editing is a highly regulated process. We found that many pseudogenes and other lncRNAs are also extensively down-regulated in the absence of ADARs in the embryo but not in the fourth larval (L4) stage. This down-regulation is not observed upon additional knockout of RNAi. Furthermore, levels of siRNAs aligned to pseudogenes in ADAR mutants are enhanced. Taken together, our results suggest a role for RNA editing in normal growth and development by regulating silencing via RNAi.
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Affiliation(s)
- Boaz Goldstein
- Faculty of Biology, Technion-Israel Institute of Technology, Technion City, Haifa 32000, Israel
| | - Lily Agranat-Tamir
- Faculty of Biology, Technion-Israel Institute of Technology, Technion City, Haifa 32000, Israel
| | - Dean Light
- Faculty of Biology, Technion-Israel Institute of Technology, Technion City, Haifa 32000, Israel
| | - Orna Ben-Naim Zgayer
- Faculty of Biology, Technion-Israel Institute of Technology, Technion City, Haifa 32000, Israel
| | - Alla Fishman
- Faculty of Biology, Technion-Israel Institute of Technology, Technion City, Haifa 32000, Israel
| | - Ayelet T Lamm
- Faculty of Biology, Technion-Israel Institute of Technology, Technion City, Haifa 32000, Israel
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189
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Fisher AJ, Beal PA. Effects of Aicardi-Goutières syndrome mutations predicted from ADAR-RNA structures. RNA Biol 2016; 14:164-170. [PMID: 27937139 DOI: 10.1080/15476286.2016.1267097] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Adenosine (A) to inosine (I) RNA editing is important for life in metazoan organisms. Dysregulation or mutations that compromise the efficacy of A to I editing results in neurological disorders and a shorten life span. These reactions are catalyzed by adenosine deaminases acting on RNA (ADARs), which hydrolytically deaminate adenosines in regions of duplex RNA. Because inosine mimics guanosine in hydrogen bonding, this prolific RNA editing alters the sequence and structural information in the RNA landscape. Aicardi-Goutières syndrome (AGS) is a severe childhood autoimmune disease that is one of a broader set of inherited disorders characterized by constitutive upregulation of type I interferon (IFN) referred to as type I interferonopathies. AGS is caused by mutations in multiple genes whose protein products, including ADAR1, are all involved in nucleic acid metabolism or sensing. The recent crystal structures of human ADAR2 deaminase domain complexed with duplex RNA substrates enabled modeling of how AGS causing mutations may influence RNA binding and catalysis. The mutations can be broadly characterized into three groups; mutations on RNA-binding loops that directly affect RNA binding, "second-layer" mutations that can alter the disposition of RNA-binding loops, and mutations that can alter the position of an α-helix bearing an essential catalytic residue.
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Affiliation(s)
- Andrew J Fisher
- a Department of Chemistry , University of California , Davis , CA , USA.,b Department of Molecular and Cellular Biology , University of California , Davis , CA , USA
| | - Peter A Beal
- a Department of Chemistry , University of California , Davis , CA , USA
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190
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Filippini A, Bonini D, La Via L, Barbon A. The Good and the Bad of Glutamate Receptor RNA Editing. Mol Neurobiol 2016; 54:6795-6805. [DOI: 10.1007/s12035-016-0201-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 10/11/2016] [Indexed: 12/15/2022]
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191
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Liu X, Huang K, Hou Q, Sun Z, Wang B, Lin G, Li D, Liu Y, Xu X, Hu C. Identification and characterization of a constitutively expressed Ctenopharyngodon idella ADAR1 splicing isoform (CiADAR1a). DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2016; 63:10-17. [PMID: 27185203 DOI: 10.1016/j.dci.2016.05.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 05/12/2016] [Accepted: 05/12/2016] [Indexed: 06/05/2023]
Abstract
As one member of ADAR family, ADAR1 (adenosine deaminase acting on RNA 1) can convert adenosine to inosine within dsRNA. There are many ADAR1 splicing isoforms in mammals, including an interferon (IFN) inducible ∼150 kD protein (ADAR1-p150) and a constitutively expressed ∼110 kD protein (ADAR1-p110). The structural diversity of ADAR1 splicing isoforms may reflect their multiple functions. ADAR1 splicing isoforms were also found in fish. In our previous study, we have cloned and identified two different grass carp ADAR1 splicing isoforms, i.e. CiADAR1 and CiADAR1-like, both of them are IFN-inducible proteins. In this paper, we identified a novel CiADAR1 splicing isoform gene (named CiADAR1a). CiADAR1a gene contains 15 exons and 14 introns. Its full-length cDNA is comprised of a 5' UTR (359 bp), a 3' UTR (229 bp) and a 2952 bp ORF encoding a polypeptide of 983 amino acids with one Z-DNA binding domain, three dsRNA binding motifs and a highly conserved hydrolytic deamination domain. CiADAR1a was constitutively expressed in Ctenopharyngodon idella kidney (CIK) cells regardless of Poly I:C stimulation by Western blot assay. In normal condition, CiADAR1a was found to be present mainly in the nucleus. After treatment with Poly I:C, it gradually shifted to cytoplasm. To further investigate the mechanism of transcriptional regulation of CiADAR1a, we cloned and identified its promoter sequence. The transcriptional start site of CiADAR1a is mapped within the truncated exon 2. CiADAR1a promoter is 1303 bp in length containing 4 IRF-Es. In the present study, we constructed pcDNA3.1 eukaryotic expression vectors with IRF1 and IRF3 and co-transfected them with pGL3-CiADAR1a promoter into CIK cells. The results showed that neither the over-expression of IRF1 or IRF3 nor Poly I:C stimulation significantly impacted CiADAR1a promoter activity in CIK cells. Together, according to the molecular and expression characteristics, subcellular localization and transcriptional regulatory mechanism, we deduced that CiADAR1a shared a high degree of homology with mammalian ADAR1-p110.
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Affiliation(s)
- Xiancheng Liu
- Department of Bioscience, College of Life Science, Nanchang University, Nanchang 330031, China
| | - Keyi Huang
- Department of Bioscience, College of Life Science, Nanchang University, Nanchang 330031, China
| | - Qunhao Hou
- Department of Bioscience, College of Life Science, Nanchang University, Nanchang 330031, China
| | - Zhicheng Sun
- Department of Bioscience, College of Life Science, Nanchang University, Nanchang 330031, China
| | - Binhua Wang
- Department of Bioscience, College of Life Science, Nanchang University, Nanchang 330031, China
| | - Gang Lin
- Department of Bioscience, College of Life Science, Nanchang University, Nanchang 330031, China
| | - Dongming Li
- Fuzhou Medical College, Nanchang University, Fuzhou 344000, China
| | - Yong Liu
- Department of Bioscience, College of Life Science, Nanchang University, Nanchang 330031, China
| | - Xiaowen Xu
- Department of Bioscience, College of Life Science, Nanchang University, Nanchang 330031, China
| | - Chengyu Hu
- Department of Bioscience, College of Life Science, Nanchang University, Nanchang 330031, China.
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192
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Stellos K, Gatsiou A, Stamatelopoulos K, Perisic Matic L, John D, Lunella FF, Jaé N, Rossbach O, Amrhein C, Sigala F, Boon RA, Fürtig B, Manavski Y, You X, Uchida S, Keller T, Boeckel JN, Franco-Cereceda A, Maegdefessel L, Chen W, Schwalbe H, Bindereif A, Eriksson P, Hedin U, Zeiher AM, Dimmeler S. Adenosine-to-inosine RNA editing controls cathepsin S expression in atherosclerosis by enabling HuR-mediated post-transcriptional regulation. Nat Med 2016; 22:1140-1150. [PMID: 27595325 DOI: 10.1038/nm.4172] [Citation(s) in RCA: 190] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 07/20/2016] [Indexed: 12/14/2022]
Abstract
Adenosine-to-inosine (A-to-I) RNA editing, which is catalyzed by a family of adenosine deaminase acting on RNA (ADAR) enzymes, is important in the epitranscriptomic regulation of RNA metabolism. However, the role of A-to-I RNA editing in vascular disease is unknown. Here we show that cathepsin S mRNA (CTSS), which encodes a cysteine protease associated with angiogenesis and atherosclerosis, is highly edited in human endothelial cells. The 3' untranslated region (3' UTR) of the CTSS transcript contains two inverted repeats, the AluJo and AluSx+ regions, which form a long stem-loop structure that is recognized by ADAR1 as a substrate for editing. RNA editing enables the recruitment of the stabilizing RNA-binding protein human antigen R (HuR; encoded by ELAVL1) to the 3' UTR of the CTSS transcript, thereby controlling CTSS mRNA stability and expression. In endothelial cells, ADAR1 overexpression or treatment of cells with hypoxia or with the inflammatory cytokines interferon-γ and tumor-necrosis-factor-α induces CTSS RNA editing and consequently increases cathepsin S expression. ADAR1 levels and the extent of CTSS RNA editing are associated with changes in cathepsin S levels in patients with atherosclerotic vascular diseases, including subclinical atherosclerosis, coronary artery disease, aortic aneurysms and advanced carotid atherosclerotic disease. These results reveal a previously unrecognized role of RNA editing in gene expression in human atherosclerotic vascular diseases.
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Affiliation(s)
- Konstantinos Stellos
- Institute of Cardiovascular Regeneration, Center of Molecular Medicine, Goethe University Frankfurt, Frankfurt, Germany.,Department of Cardiology, Center of Internal Medicine, Goethe University Frankfurt, Frankfurt, Germany.,German Center of Cardiovascular Research (Deutsches Zentrum für Herz-Kreislaufforschung; DZHK), Rhein-Main Partner Site, Frankfurt, Germany
| | - Aikaterini Gatsiou
- Institute of Cardiovascular Regeneration, Center of Molecular Medicine, Goethe University Frankfurt, Frankfurt, Germany.,German Center of Cardiovascular Research (Deutsches Zentrum für Herz-Kreislaufforschung; DZHK), Rhein-Main Partner Site, Frankfurt, Germany
| | - Kimon Stamatelopoulos
- Department of Clinical Therapeutics, Alexandra Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Ljubica Perisic Matic
- Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden
| | - David John
- Institute of Cardiovascular Regeneration, Center of Molecular Medicine, Goethe University Frankfurt, Frankfurt, Germany.,German Center of Cardiovascular Research (Deutsches Zentrum für Herz-Kreislaufforschung; DZHK), Rhein-Main Partner Site, Frankfurt, Germany
| | - Federica Francesca Lunella
- Institute of Cardiovascular Regeneration, Center of Molecular Medicine, Goethe University Frankfurt, Frankfurt, Germany.,German Center of Cardiovascular Research (Deutsches Zentrum für Herz-Kreislaufforschung; DZHK), Rhein-Main Partner Site, Frankfurt, Germany
| | - Nicolas Jaé
- Institute of Cardiovascular Regeneration, Center of Molecular Medicine, Goethe University Frankfurt, Frankfurt, Germany.,German Center of Cardiovascular Research (Deutsches Zentrum für Herz-Kreislaufforschung; DZHK), Rhein-Main Partner Site, Frankfurt, Germany
| | - Oliver Rossbach
- Institute of Biochemistry, University of Giessen, Giessen, Germany
| | - Carolin Amrhein
- Institute of Cardiovascular Regeneration, Center of Molecular Medicine, Goethe University Frankfurt, Frankfurt, Germany
| | - Frangiska Sigala
- Department of Vascular Surgery, 1st Propaedeutic Department of Surgery, Hippocratio General Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Reinier A Boon
- Institute of Cardiovascular Regeneration, Center of Molecular Medicine, Goethe University Frankfurt, Frankfurt, Germany.,German Center of Cardiovascular Research (Deutsches Zentrum für Herz-Kreislaufforschung; DZHK), Rhein-Main Partner Site, Frankfurt, Germany
| | - Boris Fürtig
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Frankfurt, Germany
| | - Yosif Manavski
- Institute of Cardiovascular Regeneration, Center of Molecular Medicine, Goethe University Frankfurt, Frankfurt, Germany.,German Center of Cardiovascular Research (Deutsches Zentrum für Herz-Kreislaufforschung; DZHK), Rhein-Main Partner Site, Frankfurt, Germany
| | - Xintian You
- Laboratory of Functional Genomics and Systems Biology, Max Delbrück Center for Molecular Medicine Berlin-Buch, Berlin, Germany
| | - Shizuka Uchida
- Institute of Cardiovascular Regeneration, Center of Molecular Medicine, Goethe University Frankfurt, Frankfurt, Germany.,German Center of Cardiovascular Research (Deutsches Zentrum für Herz-Kreislaufforschung; DZHK), Rhein-Main Partner Site, Frankfurt, Germany
| | - Till Keller
- Department of Cardiology, Center of Internal Medicine, Goethe University Frankfurt, Frankfurt, Germany.,German Center of Cardiovascular Research (Deutsches Zentrum für Herz-Kreislaufforschung; DZHK), Rhein-Main Partner Site, Frankfurt, Germany
| | - Jes-Niels Boeckel
- Institute of Cardiovascular Regeneration, Center of Molecular Medicine, Goethe University Frankfurt, Frankfurt, Germany.,German Center of Cardiovascular Research (Deutsches Zentrum für Herz-Kreislaufforschung; DZHK), Rhein-Main Partner Site, Frankfurt, Germany
| | - Anders Franco-Cereceda
- Cardiothoracic Surgery Unit, Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden
| | - Lars Maegdefessel
- Cardiovascular Medicine Unit, Department of Medicine, Karolinska Institute, Stockholm, Sweden.,Department of Vascular and Endovascular Surgery, Technical University Munich, Munich, Germany
| | - Wei Chen
- Laboratory of Functional Genomics and Systems Biology, Max Delbrück Center for Molecular Medicine Berlin-Buch, Berlin, Germany
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Frankfurt, Germany
| | | | - Per Eriksson
- Cardiovascular Medicine Unit, Department of Medicine, Karolinska Institute, Stockholm, Sweden
| | - Ulf Hedin
- Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden
| | - Andreas M Zeiher
- Department of Cardiology, Center of Internal Medicine, Goethe University Frankfurt, Frankfurt, Germany.,German Center of Cardiovascular Research (Deutsches Zentrum für Herz-Kreislaufforschung; DZHK), Rhein-Main Partner Site, Frankfurt, Germany
| | - Stefanie Dimmeler
- Institute of Cardiovascular Regeneration, Center of Molecular Medicine, Goethe University Frankfurt, Frankfurt, Germany.,German Center of Cardiovascular Research (Deutsches Zentrum für Herz-Kreislaufforschung; DZHK), Rhein-Main Partner Site, Frankfurt, Germany
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193
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Chen W, An D, Xu H, Cheng X, Wang S, Yu W, Yu D, Zhao D, Sun Y, Deng W, Tang Y, Yin S. Effects of social isolation and re-socialization on cognition and ADAR1 (p110) expression in mice. PeerJ 2016; 4:e2306. [PMID: 27602277 PMCID: PMC4994079 DOI: 10.7717/peerj.2306] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2016] [Accepted: 07/09/2016] [Indexed: 11/20/2022] Open
Abstract
It has been reported that social isolation stress could be a key factor that leads to cognitive deficit for both humans and rodent models. However, detailed mechanisms are not yet clear. ADAR1 (Adenosine deaminase acting on RNA) is an enzyme involved in RNA editing that has a close relation to cognitive function. We have hypothesized that social isolation stress may impact the expression of ADAR1 in the brain of mice with cognitive deficit. To test our hypothesis, we evaluated the cognition ability of mice isolated for different durations (2, 4, and 8 weeks) using object recognition and object location tests; we also measured ADAR1 expression in hippocampus and cortex using immunohistochemistry and western blot. Our study showed that social isolation stress induced spatial and non-spatial cognition deficits of the tested mice. In addition, social isolation significantly increased both the immunoreactivity and protein expression of ADAR1 (p110) in the hippocampus and frontal cortex. Furthermore, re-socialization could not only recover the cognition deficits, but also bring ADAR1 (p110) immunoreactivity of hippocampus and frontal cortex, as well as ADAR1 (p110) protein expression of hippocampus back to the normal level for the isolated mice in adolescence. In conclusion, social isolation stress significantly increases ADAR1 (p110) expression in the hippocampus and frontal cortex of the mice with cognitive deficit. This finding may open a window to better understand the reasons (e.g., epigenetic change) that are responsible for social isolation-induced cognitive deficit and help the development of novel therapies for the resulted diseases.
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Affiliation(s)
- Wei Chen
- College of Basic Medical Sciences, Dalian Medical University, Dalian, China
| | - Dong An
- College of Basic Medical Sciences, Dalian Medical University, Dalian, China
| | - Hong Xu
- Department of Physiology Laboratory, Dalian Medical University, Dalian, China
| | - Xiaoxin Cheng
- College of Basic Medical Sciences, Dalian Medical University, Dalian, China
| | - Shiwei Wang
- Menzies Research Institute, University of Tasmania, Tasmania, Australia
| | - Weizhi Yu
- College of Basic Medical Sciences, Dalian Medical University, Dalian, China
| | - Deqin Yu
- College of Basic Medical Sciences, Dalian Medical University, Dalian, China
| | - Dan Zhao
- College of Basic Medical Sciences, Dalian Medical University, Dalian, China
| | - Yiping Sun
- College of Basic Medical Sciences, Dalian Medical University, Dalian, China
| | - Wuguo Deng
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, China
| | - Yiyuan Tang
- Department of Psychological Sciences, Texas Tech University, Lubbock, United States
| | - Shengming Yin
- College of Basic Medical Sciences, Dalian Medical University, Dalian, China
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194
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Zipeto MA, Court AC, Sadarangani A, Delos Santos NP, Balaian L, Chun HJ, Pineda G, Morris SR, Mason CN, Geron I, Barrett C, Goff DJ, Wall R, Pellecchia M, Minden M, Frazer KA, Marra MA, Crews LA, Jiang Q, Jamieson CHM. ADAR1 Activation Drives Leukemia Stem Cell Self-Renewal by Impairing Let-7 Biogenesis. Cell Stem Cell 2016; 19:177-191. [PMID: 27292188 PMCID: PMC4975616 DOI: 10.1016/j.stem.2016.05.004] [Citation(s) in RCA: 165] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2016] [Revised: 04/12/2016] [Accepted: 05/06/2016] [Indexed: 12/17/2022]
Abstract
Post-transcriptional adenosine-to-inosine RNA editing mediated by adenosine deaminase acting on RNA1 (ADAR1) promotes cancer progression and therapeutic resistance. However, ADAR1 editase-dependent mechanisms governing leukemia stem cell (LSC) generation have not been elucidated. In blast crisis chronic myeloid leukemia (BC CML), we show that increased JAK2 signaling and BCR-ABL1 amplification activate ADAR1. In a humanized BC CML mouse model, combined JAK2 and BCR-ABL1 inhibition prevents LSC self-renewal commensurate with ADAR1 downregulation. Lentiviral ADAR1 wild-type, but not an editing-defective ADAR1(E912A) mutant, induces self-renewal gene expression and impairs biogenesis of stem cell regulatory let-7 microRNAs. Combined RNA sequencing, qRT-PCR, CLIP-ADAR1, and pri-let-7 mutagenesis data suggest that ADAR1 promotes LSC generation via let-7 pri-microRNA editing and LIN28B upregulation. A small-molecule tool compound antagonizes ADAR1's effect on LSC self-renewal in stromal co-cultures and restores let-7 biogenesis. Thus, ADAR1 activation represents a unique therapeutic vulnerability in LSCs with active JAK2 signaling.
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Affiliation(s)
- Maria Anna Zipeto
- Division of Regenerative Medicine, Department of Medicine, Moores Cancer Center and Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Angela C Court
- Division of Regenerative Medicine, Department of Medicine, Moores Cancer Center and Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Anil Sadarangani
- Division of Regenerative Medicine, Department of Medicine, Moores Cancer Center and Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Nathaniel P Delos Santos
- Division of Regenerative Medicine, Department of Medicine, Moores Cancer Center and Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Larisa Balaian
- Division of Regenerative Medicine, Department of Medicine, Moores Cancer Center and Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Hye-Jung Chun
- Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
| | - Gabriel Pineda
- Division of Regenerative Medicine, Department of Medicine, Moores Cancer Center and Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Sheldon R Morris
- Division of Regenerative Medicine, Department of Medicine, Moores Cancer Center and Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Cayla N Mason
- Division of Regenerative Medicine, Department of Medicine, Moores Cancer Center and Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Ifat Geron
- Division of Regenerative Medicine, Department of Medicine, Moores Cancer Center and Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Christian Barrett
- Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Daniel J Goff
- Division of Regenerative Medicine, Department of Medicine, Moores Cancer Center and Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Russell Wall
- Division of Regenerative Medicine, Department of Medicine, Moores Cancer Center and Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Maurizio Pellecchia
- School of Medicine, University of California Riverside, Riverside, CA 92521, USA
| | - Mark Minden
- Princess Margaret Hospital, Toronto, ON M5G 2M9, Canada
| | - Kelly A Frazer
- Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Marco A Marra
- Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
| | - Leslie A Crews
- Division of Regenerative Medicine, Department of Medicine, Moores Cancer Center and Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Qingfei Jiang
- Division of Regenerative Medicine, Department of Medicine, Moores Cancer Center and Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
| | - Catriona H M Jamieson
- Division of Regenerative Medicine, Department of Medicine, Moores Cancer Center and Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
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195
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Liddicoat BJ, Hartner JC, Piskol R, Ramaswami G, Chalk AM, Kingsley PD, Sankaran VG, Wall M, Purton LE, Seeburg PH, Palis J, Orkin SH, Lu J, Li JB, Walkley CR. Adenosine-to-inosine RNA editing by ADAR1 is essential for normal murine erythropoiesis. Exp Hematol 2016; 44:947-63. [PMID: 27373493 DOI: 10.1016/j.exphem.2016.06.250] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 06/02/2016] [Indexed: 11/17/2022]
Abstract
Adenosine deaminases that act on RNA (ADARs) convert adenosine residues to inosine in double-stranded RNA. In vivo, ADAR1 is essential for the maintenance of hematopoietic stem/progenitors. Whether other hematopoietic cell types also require ADAR1 has not been assessed. Using erythroid- and myeloid-restricted deletion of Adar1, we demonstrate that ADAR1 is dispensable for myelopoiesis but is essential for normal erythropoiesis. Adar1-deficient erythroid cells display a profound activation of innate immune signaling and high levels of cell death. No changes in microRNA levels were found in ADAR1-deficient erythroid cells. Using an editing-deficient allele, we demonstrate that RNA editing is the essential function of ADAR1 during erythropoiesis. Mapping of adenosine-to-inosine editing in purified erythroid cells identified clusters of hyperedited adenosines located in long 3'-untranslated regions of erythroid-specific transcripts and these are ADAR1-specific editing events. ADAR1-mediated RNA editing is essential for normal erythropoiesis.
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Affiliation(s)
- Brian J Liddicoat
- St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia; Department of Medicine, St. Vincent's Hospital, University of Melbourne, Fitzroy, Victoria, Australia
| | - Jochen C Hartner
- Taconic Biosciences, Cologne, Germany; Department of Pediatric Oncology, Dana-Farber Cancer Institute, Division of Hematology/Oncology and Stem Cell Program, Children's Hospital Boston, Harvard Stem Cell Institute, Harvard Medical School, Boston, MA, USA
| | - Robert Piskol
- Department of Genetics, Stanford University, Stanford, CA, USA
| | - Gokul Ramaswami
- Department of Genetics, Stanford University, Stanford, CA, USA
| | - Alistair M Chalk
- St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia; Department of Medicine, St. Vincent's Hospital, University of Melbourne, Fitzroy, Victoria, Australia
| | - Paul D Kingsley
- Center for Pediatric Biomedical Research, Department of Pediatrics, University of Rochester Medical Center, Rochester, NY, USA
| | - Vijay G Sankaran
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Division of Hematology/Oncology and Stem Cell Program, Children's Hospital Boston, Harvard Stem Cell Institute, Harvard Medical School, Boston, MA, USA
| | - Meaghan Wall
- Victorian Cancer Cytogenetics Service, St. Vincent's Hospital, Fitzroy, Victoria, Australia
| | - Louise E Purton
- St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia; Department of Medicine, St. Vincent's Hospital, University of Melbourne, Fitzroy, Victoria, Australia
| | - Peter H Seeburg
- Department of Molecular Neurobiology, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - James Palis
- Center for Pediatric Biomedical Research, Department of Pediatrics, University of Rochester Medical Center, Rochester, NY, USA
| | - Stuart H Orkin
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Division of Hematology/Oncology and Stem Cell Program, Children's Hospital Boston, Harvard Stem Cell Institute, Harvard Medical School, Boston, MA, USA; Howard Hughes Medical Institute, Boston, MA, USA
| | - Jun Lu
- Department of Genetics and Yale Stem Cell Center, Yale University, New Haven, CT, USA
| | - Jin Billy Li
- Department of Genetics, Stanford University, Stanford, CA, USA
| | - Carl R Walkley
- St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia; Department of Medicine, St. Vincent's Hospital, University of Melbourne, Fitzroy, Victoria, Australia.
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196
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Hoernes TP, Erlacher MD. Translating the epitranscriptome. WILEY INTERDISCIPLINARY REVIEWS-RNA 2016; 8. [PMID: 27345446 PMCID: PMC5215311 DOI: 10.1002/wrna.1375] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 05/25/2016] [Accepted: 05/31/2016] [Indexed: 12/14/2022]
Abstract
RNA modifications are indispensable for the translation machinery to provide accurate and efficient protein synthesis. Whereas the importance of transfer RNA (tRNA) and ribosomal RNA (rRNA) modifications has been well described and is unquestioned for decades, the significance of internal messenger RNA (mRNA) modifications has only recently been revealed. Novel experimental methods have enabled the identification of thousands of modified sites within the untranslated and translated regions of mRNAs. Thus far, N6‐methyladenosine (m6A), pseudouridine (Ψ), 5‐methylcytosine (m5C) and N1‐methyladenosine (m1A) were identified in eukaryal, and to some extent in prokaryal mRNAs. Several of the functions of these mRNA modifications have previously been reported, but many aspects remain elusive. Modifications can be important factors for the direct regulation of protein synthesis. The potential diversification of genomic information and regulation of RNA expression through editing and modifying mRNAs is versatile and many questions need to be addressed to completely elucidate the role of mRNA modifications. Herein, we summarize and highlight some recent findings on various co‐ and post‐transcriptional modifications, describing the impact of these processes on gene expression, with emphasis on protein synthesis. WIREs RNA 2017, 8:e1375. doi: 10.1002/wrna.1375 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Thomas Philipp Hoernes
- Division of Genomics and RNomics, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Matthias David Erlacher
- Division of Genomics and RNomics, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
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197
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Gasparini CF, Smith RA, Griffiths LR. Genetic insights into migraine and glutamate: a protagonist driving the headache. J Neurol Sci 2016; 367:258-68. [PMID: 27423601 DOI: 10.1016/j.jns.2016.06.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 05/11/2016] [Accepted: 06/08/2016] [Indexed: 12/12/2022]
Abstract
Migraine is a complex polygenic disorder that continues to be a great source of morbidity in the developed world with a prevalence of 12% in the Caucasian population. Genetic and pharmacological studies have implicated the glutamate pathway in migraine pathophysiology. Glutamate profoundly impacts brain circuits that regulate core symptom domains in a range of neuropsychiatric conditions and thus remains a "hot" target for drug discovery. Glutamate has been implicated in cortical spreading depression (CSD), the phenomenon responsible for migraine with aura and in animal models carrying FHM mutations. Genotyping case-control studies have shown an association between glutamate receptor genes, namely, GRIA1 and GRIA3 with migraine with indirect supporting evidence from GWAS. New evidence localizes PRRT2 at glutamatergic synapses and shows it affects glutamate signalling and glutamate receptor activity via interactions with GRIA1. Glutamate-system defects have also been recently implicated in a novel FHM2 ATP1A2 disease-mutation mouse model. Adding to the growing evidence neurophysiological findings support a role for glutamate in cortical excitability. In addition to the existence of multiple genes to choreograph the functions of fast-signalling glutamatergic neurons, glutamate receptor diversity and regulation is further increased by the post-translational mechanisms of RNA editing and miRNAs. Ongoing genetic studies, GWAS and meta-analysis implicate neurogenic mechanisms in migraine pathology and the first genome-wide associated locus for migraine on chromosome X. Finally, in addition to glutamate modulating therapies, the kynurenine pathway has emerged as a candidate for involvement in migraine pathophysiology. In this review we discuss recent genetic evidence and glutamate modulating therapies that bear on the hypothesis that a glutamatergic mechanism may be involved in migraine susceptibility.
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Affiliation(s)
- Claudia F Gasparini
- Menzies Health Institute Queensland, Griffith University Gold Coast, Parklands Drive, Southport, QLD 4222, Australia
| | - Robert A Smith
- Genomics Research Centre, Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Queensland University of Technology, Musk Ave, Kelvin Grove, QLD 4059, Australia
| | - Lyn R Griffiths
- Genomics Research Centre, Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Queensland University of Technology, Musk Ave, Kelvin Grove, QLD 4059, Australia.
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198
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Savva YA, Rezaei A, St Laurent G, Reenan RA. Reprogramming, Circular Reasoning and Self versus Non-self: One-Stop Shopping with RNA Editing. Front Genet 2016; 7:100. [PMID: 27458478 PMCID: PMC4937755 DOI: 10.3389/fgene.2016.00100] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 05/23/2016] [Indexed: 01/08/2023] Open
Abstract
Transcription of genetic information from archival DNA into RNA molecule working copies is vital for proper cellular function and is highly accurate. In turn, RNAs serve structural, enzymatic, and regulatory roles, as well as being informational templates for the ribosomal translation of proteins. Following RNA synthesis, maturing of RNA molecules occurs through various RNA processing events. One component of the collection of processes involving RNA species, broadly defined as RNA metabolism, is the RNA-editing pathway and is found in all animals. Acting specifically on RNA substrates with double-stranded character, RNA editing has been shown to regulate a plethora of genomic outputs, including gene recoding, RNA splicing, biogenesis and targeting actions of microRNAs and small interfering RNAs, and global gene expression. Recent evidence suggests that RNA modifications mediated via RNA editing influence the biogenesis of circular RNAs and safeguard against aberrant innate immune responses generated to endogenous RNA sources. These novel roles have the potential to contribute new insights into molecular mechanisms underlying pathogenesis mediated by mishandling of double-stranded RNA. Here, we discuss recent advances in the field, which highlight novel roles associated with the RNA-editing process and emphasize their importance during cellular RNA metabolism. In addition, we highlight the relevance of these newly discovered roles in the context of neurological disorders and the more general concept of innate recognition of self versus non-self.
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Affiliation(s)
- Yiannis A Savva
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence RI, USA
| | - Ali Rezaei
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence RI, USA
| | - Georges St Laurent
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence RI, USA
| | - Robert A Reenan
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence RI, USA
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199
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Guo J, Wang X, Lü X, Jing R, Li J, Li C, Wang D, Bi B, Chen X, Wang F, Sun S, Gong J, Azadzoi KM, Yang JH. Unraveling molecular effects of ADAR1 overexpression in HEK293T cells by label-free quantitative proteomics. Cell Cycle 2016; 15:1591-601. [PMID: 27104882 DOI: 10.1080/15384101.2016.1176657] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
ADAR1 is a double-stranded RNA (dsRNA) editing enzyme that specifically converts adenosine to inosine. ADAR1 is ubiquitously expressed in eukaryotes and participate in various cellular processes such as differentiation, proliferation and immune responses. We report here a new proteomics study of HEK293T cells with and without ADAR1 overexpression. The up- and down-regulated proteins by ADAR1 overexpression are identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) followed by label-free protein quantification. Totally 1,495 proteins (FDR < 0.01) are identified, among which 211 are up- and 159 are down-regulated for at least 1.5-fold (n = 3, p < 0.05). Gene ontology analysis reveals that these ADAR1-regulated proteins are involved in protein translation and cell cycle regulation. Bioinformatics analysis identifies a closely related network consistent for the protein translation machinery and a tightly connected network through proliferating cell nuclear antigen (PCNA)-interactions. Up-regulation of the proteins in the PCNA-mediated cell proliferation network is confirmed by Western blotting. In addition, ADAR1 overexpression is confirmed to increase cell proliferation in HEK293T cells and A549 cells. We conclude that ADAR1 overexpression modulates the protein translation and cell cycle networks through PCNA-mediated protein-protein interaction to promote cell proliferation in HEK293 cells.
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Affiliation(s)
- Jisheng Guo
- a Cancer Research Center, Shandong University School of Medicine , Jinan , China
| | - Xiaoyue Wang
- a Cancer Research Center, Shandong University School of Medicine , Jinan , China
| | - Xin Lü
- a Cancer Research Center, Shandong University School of Medicine , Jinan , China
| | - Ruirui Jing
- a Cancer Research Center, Shandong University School of Medicine , Jinan , China
| | - Junqiang Li
- a Cancer Research Center, Shandong University School of Medicine , Jinan , China
| | - CuiLing Li
- a Cancer Research Center, Shandong University School of Medicine , Jinan , China
| | - Daoguang Wang
- a Cancer Research Center, Shandong University School of Medicine , Jinan , China
| | - Baibin Bi
- a Cancer Research Center, Shandong University School of Medicine , Jinan , China
| | - Xinjun Chen
- a Cancer Research Center, Shandong University School of Medicine , Jinan , China
| | - Fengqin Wang
- a Cancer Research Center, Shandong University School of Medicine , Jinan , China
| | - Shengnan Sun
- a Cancer Research Center, Shandong University School of Medicine , Jinan , China
| | - Jing Gong
- a Cancer Research Center, Shandong University School of Medicine , Jinan , China
| | - Kazem M Azadzoi
- b Departments of Surgery and Urology , VA Boston Healthcare System, Boston University School of Medicine , Boston , MA , USA
| | - Jing-Hua Yang
- a Cancer Research Center, Shandong University School of Medicine , Jinan , China.,b Departments of Surgery and Urology , VA Boston Healthcare System, Boston University School of Medicine , Boston , MA , USA
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The role of RNA editing by ADAR1 in prevention of innate immune sensing of self-RNA. J Mol Med (Berl) 2016; 94:1095-1102. [PMID: 27044320 DOI: 10.1007/s00109-016-1416-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 03/16/2016] [Accepted: 03/24/2016] [Indexed: 12/25/2022]
Abstract
The innate immune system is the first line of the cellular defence against invading pathogens. A critical component of this defence is the capacity to discriminate foreign RNA molecules, which are distinct from most cellular RNAs in structure and/or modifications. However, a series of rare autoimmune/autoinflammatory diseases in humans highlight the propensity for the innate immune sensing system to be activated by endogenous cellular double-stranded RNAs (dsRNAs), underscoring the fine line between distinguishing self from non-self. The RNA editing enzyme ADAR1 has recently emerged as a key regulator that prevents innate immune pathway activation, principally the cytosolic dsRNA sensor MDA5, from inducing interferon in response to double-stranded RNA structures within endogenous RNAs. Adenosine-to-Inosine RNA editing by ADAR1 is proposed to destabilise duplexes formed from inverted repetitive elements within RNAs, which appear to prevent MDA5 from sensing these RNA as virus-like in the cytoplasm. Aberrant activation of these pathways has catastrophic effects at both a cellular and organismal level, contributing to one of the causes of the conditions collectively known as the type I interferonopathies.
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