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Karlström V, Sagredo EA, Planells J, Welinder C, Jungfleisch J, Barrera-Conde A, Engfors L, Daniel C, Gebauer F, Visa N, Öhman M. ADAR3 modulates neuronal differentiation and regulates mRNA stability and translation. Nucleic Acids Res 2024:gkae753. [PMID: 39217468 DOI: 10.1093/nar/gkae753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 08/20/2024] [Indexed: 09/04/2024] Open
Abstract
ADAR3 is a catalytically inactive member of the family of adenosine deaminases acting on RNA (ADARs). Here we have investigated its function in the context of the developing mouse brain. The expression of ADAR3 gradually increases throughout embryogenesis and drops after birth. Using primary cortical neurons, we show that ADAR3 is only expressed in a subpopulation of in vitro differentiated neurons, which suggests specific functions rather than being a general regulator of ADAR editing in the brain. The analysis of the ADAR3 interactome suggested a role in mRNA stability and translation, and we show that expression of ADAR3 in a neuronal cell line that is otherwise ADAR3-negative changes the expression and stability of a large number of mRNAs. Notably, we show that ADAR3 associates with polysomes and inhibits translation. We propose that ADAR3 binds to target mRNAs and stabilizes them in non-productive polysome complexes. Interestingly, the expression of ADAR3 downregulates genes related to neuronal differentiation and inhibits neurofilament outgrowth in vitro. In summary, we propose that ADAR3 negatively regulates neuronal differentiation, and that it does so by regulating mRNA stability and translation in an editing-independent manner.
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Affiliation(s)
- Victor Karlström
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrhenius väg 20C, Stockholm SE-106 91, Sweden
| | - Eduardo A Sagredo
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrhenius väg 20C, Stockholm SE-106 91, Sweden
| | - Jordi Planells
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrhenius väg 20C, Stockholm SE-106 91, Sweden
| | - Charlotte Welinder
- Mass Spectrometry, Clinical Sciences, Lund University, Lund SE-221 84, Sweden
| | - Jennifer Jungfleisch
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, ES-08003 Barcelona, Spain
| | - Andrea Barrera-Conde
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, ES-08003 Barcelona, Spain
| | - Linus Engfors
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrhenius väg 20C, Stockholm SE-106 91, Sweden
| | - Chammiran Daniel
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrhenius väg 20C, Stockholm SE-106 91, Sweden
| | - Fátima Gebauer
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, ES-08003 Barcelona, Spain
- Universitat Pompeu Fabra (UPF), ES-08003 Barcelona, Spain
| | - Neus Visa
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrhenius väg 20C, Stockholm SE-106 91, Sweden
| | - Marie Öhman
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrhenius väg 20C, Stockholm SE-106 91, Sweden
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2
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Ashley CN, Broni E, Miller WA. ADAR Family Proteins: A Structural Review. Curr Issues Mol Biol 2024; 46:3919-3945. [PMID: 38785511 PMCID: PMC11120146 DOI: 10.3390/cimb46050243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 04/22/2024] [Accepted: 04/23/2024] [Indexed: 05/25/2024] Open
Abstract
This review aims to highlight the structures of ADAR proteins that have been crucial in the discernment of their functions and are relevant to future therapeutic development. ADAR proteins can correct or diversify genetic information, underscoring their pivotal contribution to protein diversity and the sophistication of neuronal networks. ADAR proteins have numerous functions in RNA editing independent roles and through the mechanisms of A-I RNA editing that continue to be revealed. Provided is a detailed examination of the ADAR family members-ADAR1, ADAR2, and ADAR3-each characterized by distinct isoforms that offer both structural diversity and functional variability, significantly affecting RNA editing mechanisms and exhibiting tissue-specific regulatory patterns, highlighting their shared features, such as double-stranded RNA binding domains (dsRBD) and a catalytic deaminase domain (CDD). Moreover, it explores ADARs' extensive roles in immunity, RNA interference, and disease modulation, demonstrating their ambivalent nature in both the advancement and inhibition of diseases. Through this comprehensive analysis, the review seeks to underline the potential of targeting ADAR proteins in therapeutic strategies, urging continued investigation into their biological mechanisms and health implications.
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Affiliation(s)
- Carolyn N. Ashley
- Department of Medicine, Loyola University Medical Center, Loyola University Chicago, Maywood, IL 60153, USA; (C.N.A.); (E.B.)
| | - Emmanuel Broni
- Department of Medicine, Loyola University Medical Center, Loyola University Chicago, Maywood, IL 60153, USA; (C.N.A.); (E.B.)
| | - Whelton A. Miller
- Department of Medicine, Loyola University Medical Center, Loyola University Chicago, Maywood, IL 60153, USA; (C.N.A.); (E.B.)
- Department of Molecular Pharmacology & Neuroscience, Loyola University Medical Center, Loyola University Chicago, Maywood, IL 60153, USA
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3
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Zhang Y, Lei Y, Dong Y, Chen S, Sun S, Zhou F, Zhao Z, Chen B, Wei L, Chen J, Meng Z. Emerging roles of RNA ac4C modification and NAT10 in mammalian development and human diseases. Pharmacol Ther 2024; 253:108576. [PMID: 38065232 DOI: 10.1016/j.pharmthera.2023.108576] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Revised: 11/29/2023] [Accepted: 12/01/2023] [Indexed: 01/13/2024]
Abstract
RNA ac4C modification is a novel and rare chemical modification observed in mRNA. Traditional biochemical studies had primarily associated ac4C modification with tRNA and rRNA until in 2018, Arango D et al. first reported the presence of ac4C modification on mRNA and demonstrated its critical role in mRNA stability and translation regulation. Furthermore, they established that the ac4C modification on mRNA is mediated by the classical N-acetyltransferase NAT10. Subsequent studies have underscored the essential implications of NAT10 and mRNA ac4C modification across both physiological and pathological regulatory processes. In this review, we aimed to explore the discovery history of RNA ac4C modification, its detection methods, and its regulatory mechanisms in disease and physiological development. We offer a forward-looking examination and discourse concerning the employment of RNA ac4C modification as a prospective therapeutic strategy across diverse diseases. Furthermore, we comprehensively summarize the functions and mechanisms of NAT10 in gene expression regulation and pathogenesis independent of RNA ac4C modification.
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Affiliation(s)
- Yigan Zhang
- Institute of Biomedical Research, Department of Infectious Diseases, Regulatory Mechanism and Targeted Therapy for Liver Cancer Shiyan Key Laboratory, Hubei rovincial Clinical Research Center for Precise Diagnosis and Treatment of Liver Cancer, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, 442000, China; Hubei Key Laboratory of Embryonic Stem Cell Research, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, 442000, China
| | - Yumei Lei
- Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing, China
| | - Yanbin Dong
- Institute of Biophysics, Chinese Academy of Sciences, Key Laboratory of Nucleic Acid Biology, Chinese Academy of Sciences, Beijing, China
| | - Shuwen Chen
- School of Biomedical Engineering, Hubei University of Medicine, Shiyan, China
| | - Siyuan Sun
- Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing, China
| | - Fange Zhou
- The First Clinical School of Hubei University of Medicine, Shiyan, China
| | - Zhiwen Zhao
- Department of Emergency Medicine, Taihe Hospital, Hubei University of Medicine, Shiyan, China
| | - Bonan Chen
- Department of Anatomical and Cellular Pathology, State Key Laboratory of Translational Oncology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China
| | - Lv Wei
- Institute of Biophysics, Chinese Academy of Sciences, Key Laboratory of Nucleic Acid Biology, Chinese Academy of Sciences, Beijing, China.
| | - Juan Chen
- Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing, China.
| | - Zhongji Meng
- Institute of Biomedical Research, Department of Infectious Diseases, Regulatory Mechanism and Targeted Therapy for Liver Cancer Shiyan Key Laboratory, Hubei rovincial Clinical Research Center for Precise Diagnosis and Treatment of Liver Cancer, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, 442000, China; Hubei Key Laboratory of Embryonic Stem Cell Research, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, 442000, China.
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4
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Pfeiffer LS, Stafforst T. Precision RNA base editing with engineered and endogenous effectors. Nat Biotechnol 2023; 41:1526-1542. [PMID: 37735261 DOI: 10.1038/s41587-023-01927-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 07/26/2023] [Indexed: 09/23/2023]
Abstract
RNA base editing refers to the rewriting of genetic information within an intact RNA molecule and serves various functions, such as evasion of the endogenous immune system and regulation of protein function. To achieve this, certain enzymes have been discovered in human cells that catalyze the conversion of one nucleobase into another. This natural process could be exploited to manipulate and recode any base in a target transcript. In contrast to DNA base editing, analogous changes introduced in RNA are not permanent or inheritable but rather allow reversible and doseable effects that appeal to various therapeutic applications. The current practice of RNA base editing involves the deamination of adenosines and cytidines, which are converted to inosines and uridines, respectively. In this Review, we summarize current site-directed RNA base-editing strategies and highlight recent achievements to improve editing efficiency, precision, codon-targeting scope and in vivo delivery into disease-relevant tissues. Besides engineered editing effectors, we focus on strategies to harness endogenous adenosine deaminases acting on RNA (ADAR) enzymes and discuss limitations and future perspectives to apply the tools in basic research and as a therapeutic modality. We expect the field to realize the first RNA base-editing drug soon, likely on a well-defined genetic disease. However, the long-term challenge will be to carve out the sweet spot of the technology where its unique ability is exploited to modulate signaling cues, metabolism or other clinically relevant processes in a safe and doseable manner.
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Affiliation(s)
- Laura S Pfeiffer
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Thorsten Stafforst
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany.
- Gene and RNA Therapy Center, Faculty of Medicine, University of Tübingen, Tübingen, Germany.
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5
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Booth BJ, Nourreddine S, Katrekar D, Savva Y, Bose D, Long TJ, Huss DJ, Mali P. RNA editing: Expanding the potential of RNA therapeutics. Mol Ther 2023; 31:1533-1549. [PMID: 36620962 PMCID: PMC9824937 DOI: 10.1016/j.ymthe.2023.01.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 12/06/2022] [Accepted: 01/04/2023] [Indexed: 01/09/2023] Open
Abstract
RNA therapeutics have had a tremendous impact on medicine, recently exemplified by the rapid development and deployment of mRNA vaccines to combat the COVID-19 pandemic. In addition, RNA-targeting drugs have been developed for diseases with significant unmet medical needs through selective mRNA knockdown or modulation of pre-mRNA splicing. Recently, RNA editing, particularly antisense RNA-guided adenosine deaminase acting on RNA (ADAR)-based programmable A-to-I editing, has emerged as a powerful tool to manipulate RNA to enable correction of disease-causing mutations and modulate gene expression and protein function. Beyond correcting pathogenic mutations, the technology is particularly well suited for therapeutic applications that require a transient pharmacodynamic effect, such as the treatment of acute pain, obesity, viral infection, and inflammation, where it would be undesirable to introduce permanent alterations to the genome. Furthermore, transient modulation of protein function, such as altering the active sites of enzymes or the interface of protein-protein interactions, opens the door to therapeutic avenues ranging from regenerative medicine to oncology. These emerging RNA-editing-based toolsets are poised to broadly impact biotechnology and therapeutic applications. Here, we review the emerging field of therapeutic RNA editing, highlight recent laboratory advancements, and discuss the key challenges on the path to clinical development.
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Affiliation(s)
| | - Sami Nourreddine
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | | | | | | | | | | | - Prashant Mali
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA.
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6
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Yang X, Wang H, Zhang L, Yao S, Dai J, Wen G, An J, Jin H, Du Q, Hu Y, Zheng L, Chen X, Yi Z, Tuo B. Novel roles of karyopherin subunit alpha 2 in hepatocellular carcinoma. Biomed Pharmacother 2023; 163:114792. [PMID: 37121148 DOI: 10.1016/j.biopha.2023.114792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 04/05/2023] [Accepted: 04/24/2023] [Indexed: 05/02/2023] Open
Abstract
Hepatocellular carcinoma is the most common type of liver cancer and associated with a high fatality rate. This disease poses a major threat to human health worldwide. A considerable number of genetic and epigenetic factors are involved in the development of hepatocellular carcinoma. However, the molecular mechanism underlying the progression of hepatocellular carcinoma remains unclear. Karyopherin subunit alpha 2 (KPNA2), also termed importin α1, is a member of the nuclear transporter family. In recent years, KPNA2 has been gradually linked to the nuclear transport pathway for a variety of tumor-associated proteins. Furthermore, it promotes tumor development by participating in various pathophysiological processes such as cell proliferation, apoptosis, immune response, and viral infection. In hepatocellular carcinoma, it has been found that KPNA2 expression is significantly higher in liver cancer tissues versus paracancerous tissues. Moreover, it has been identified as a marker of poor prognosis and early recurrence in patients with hepatocellular carcinoma. Nevertheless, the role of KPNA2 in the development of hepatocellular carcinoma remains to be determined. This review summarizes the current knowledge on the pathogenesis and role of KPNA2 in hepatocellular carcinoma, and provides new directions and strategies for the diagnosis, treatment, and prediction of prognosis of this disease.
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Affiliation(s)
- Xingyue Yang
- Department of Gastroenterology, Digestive Disease Hospital, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Hu Wang
- Department of General Surgery, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Li Zhang
- Department of Gastroenterology, Digestive Disease Hospital, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Shun Yao
- Department of Gastroenterology, Digestive Disease Hospital, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Jing Dai
- Department of Gastroenterology, Digestive Disease Hospital, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Guorong Wen
- Department of Gastroenterology, Digestive Disease Hospital, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Jiaxing An
- Department of Gastroenterology, Digestive Disease Hospital, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Hai Jin
- Department of Gastroenterology, Digestive Disease Hospital, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Qian Du
- Department of Gastroenterology, Digestive Disease Hospital, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Yanxia Hu
- Department of Gastroenterology, Digestive Disease Hospital, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Liming Zheng
- Department of Gastroenterology, Digestive Disease Hospital, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Xingyue Chen
- Department of Gastroenterology, Digestive Disease Hospital, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Zhiqiang Yi
- Department of Gastroenterology, Digestive Disease Hospital, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Biguang Tuo
- Department of Gastroenterology, Digestive Disease Hospital, Affiliated Hospital of Zunyi Medical University, Zunyi, China; The Collaborative Innovation Center of Tissue Damage Repair and Regenerative Medicine of Zunyi Medical University, Zunyi, China.
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7
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Rosenthal JJC, Eisenberg E. Extensive Recoding of the Neural Proteome in Cephalopods by RNA Editing. Annu Rev Anim Biosci 2023; 11:57-75. [PMID: 36790891 DOI: 10.1146/annurev-animal-060322-114534] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
The coleoid cephalopods have the largest brains, and display the most complex behaviors, of all invertebrates. The molecular and cellular mechanisms that underlie these remarkable advancements remain largely unexplored. Early molecular cloning studies of squid ion channel transcripts uncovered an unusually large number of A→I RNA editing sites that recoded codons. Further cloning of other neural transcripts showed a similar pattern. The advent of deep-sequencing technologies and the associated bioinformatics allowed the mapping of RNA editing events across the entire neural transcriptomes of various cephalopods. The results were remarkable: They contained orders of magnitude more recoding editing sites than any other taxon. Although RNA editing sites are abundant in most multicellular metazoans, they rarely recode. In cephalopods, the majority of neural transcripts are recoded. Recent studies have focused on whether these events are adaptive, as well as other noncanonical aspects of cephalopod RNA editing.
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Affiliation(s)
- Joshua J C Rosenthal
- The Eugene Bell Center, The Marine Biological Laboratory, Woods Hole, Massachusetts, USA;
| | - Eli Eisenberg
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel
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8
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Li M, Yan C, Jiao Y, Xu Y, Bai C, Miao R, Jiang J, Liu J. Site-directed RNA editing by harnessing ADARs: advances and challenges. Funct Integr Genomics 2022; 22:1089-1103. [DOI: 10.1007/s10142-022-00910-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 10/12/2022] [Accepted: 10/17/2022] [Indexed: 11/04/2022]
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9
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Hajji K, Sedmík J, Cherian A, Amoruso D, Keegan LP, O'Connell MA. ADAR2 enzymes: efficient site-specific RNA editors with gene therapy aspirations. RNA (NEW YORK, N.Y.) 2022; 28:1281-1297. [PMID: 35863867 PMCID: PMC9479739 DOI: 10.1261/rna.079266.122] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The adenosine deaminase acting on RNA (ADAR) enzymes are essential for neuronal function and innate immune control. ADAR1 RNA editing prevents aberrant activation of antiviral dsRNA sensors through editing of long, double-stranded RNAs (dsRNAs). In this review, we focus on the ADAR2 proteins involved in the efficient, highly site-specific RNA editing to recode open reading frames first discovered in the GRIA2 transcript encoding the key GLUA2 subunit of AMPA receptors; ADAR1 proteins also edit many of these sites. We summarize the history of ADAR2 protein research and give an up-to-date review of ADAR2 structural studies, human ADARBI (ADAR2) mutants causing severe infant seizures, and mouse disease models. Structural studies on ADARs and their RNA substrates facilitate current efforts to develop ADAR RNA editing gene therapy to edit disease-causing single nucleotide polymorphisms (SNPs). Artificial ADAR guide RNAs are being developed to retarget ADAR RNA editing to new target transcripts in order to correct SNP mutations in them at the RNA level. Site-specific RNA editing has been expanded to recode hundreds of sites in CNS transcripts in Drosophila and cephalopods. In Drosophila and C. elegans, ADAR RNA editing also suppresses responses to self dsRNA.
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Affiliation(s)
- Khadija Hajji
- CEITEC Masaryk University, Brno 62500, Czech Republic
| | - Jiří Sedmík
- CEITEC Masaryk University, Brno 62500, Czech Republic
| | - Anna Cherian
- CEITEC Masaryk University, Brno 62500, Czech Republic
| | | | - Liam P Keegan
- CEITEC Masaryk University, Brno 62500, Czech Republic
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10
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Raghava Kurup R, Oakes EK, Manning AC, Mukherjee P, Vadlamani P, Hundley HA. RNA binding by ADAR3 inhibits adenosine-to-inosine editing and promotes expression of immune response protein MAVS. J Biol Chem 2022; 298:102267. [PMID: 35850307 PMCID: PMC9418441 DOI: 10.1016/j.jbc.2022.102267] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 07/01/2022] [Accepted: 07/05/2022] [Indexed: 12/13/2022] Open
Abstract
Members of the ADAR family of double-stranded RNA–binding proteins regulate one of the most abundant RNA modifications in humans, the deamination of adenosine to inosine. Several transcriptome-wide studies have been carried out to identify RNA targets of the active deaminases ADAR1 and ADAR2. However, our understanding of ADAR3, the brain-specific deaminase-deficient ADAR family member, is limited to a few transcripts. In this study, we identified over 3300 transcripts bound by ADAR3 and observed that binding of ADAR3 correlated with reduced editing of over 400 sites in the glioblastoma transcriptome. We further investigated the impact of ADAR3 on gene regulation of the transcript that encodes MAVS, an essential protein in the innate immune response pathway. We observed reduced editing in the MAVS 3′ UTR in cells expressing increased ADAR3 or reduced ADAR1 suggesting ADAR3 acts as a negative regulator of ADAR1-mediated editing. While neither ADAR1 knockdown or ADAR3 overexpression affected MAVS mRNA expression, we demonstrate increased ADAR3 expression resulted in upregulation of MAVS protein expression. In addition, we created a novel genetic mutant of ADAR3 that exhibited enhanced RNA binding and MAVS upregulation compared with wildtype ADAR3. Interestingly, this ADAR3 mutant no longer repressed RNA editing, suggesting ADAR3 has a unique regulatory role beyond altering editing levels. Altogether, this study provides the first global view of ADAR3-bound RNAs in glioblastoma cells and identifies both a role for ADAR3 in repressing ADAR1-mediated editing and an RNA-binding dependent function of ADAR3 in regulating MAVS expression.
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Affiliation(s)
| | - Eimile K Oakes
- Department of Biology, Indiana University, Bloomington IN 47405, USA
| | - Aidan C Manning
- Medical Sciences Program, Indiana University School of Medicine-Bloomington, Bloomington IN 47405, USA
| | - Priyanka Mukherjee
- Medical Sciences Program, Indiana University School of Medicine-Bloomington, Bloomington IN 47405, USA
| | - Pranathi Vadlamani
- Medical Sciences Program, Indiana University School of Medicine-Bloomington, Bloomington IN 47405, USA
| | - Heather A Hundley
- Department of Biology, Indiana University, Bloomington IN 47405, USA.
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11
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Schneider N, Sundaresan Y, Gopalakrishnan P, Beryozkin A, Hanany M, Levanon EY, Banin E, Ben-Aroya S, Sharon D. Inherited retinal diseases: Linking genes, disease-causing variants, and relevant therapeutic modalities. Prog Retin Eye Res 2021; 89:101029. [PMID: 34839010 DOI: 10.1016/j.preteyeres.2021.101029] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 11/11/2021] [Accepted: 11/16/2021] [Indexed: 12/11/2022]
Abstract
Inherited retinal diseases (IRDs) are a clinically complex and heterogenous group of visual impairment phenotypes caused by pathogenic variants in at least 277 nuclear and mitochondrial genes, affecting different retinal regions, and depleting the vision of affected individuals. Genes that cause IRDs when mutated are unique by possessing differing genotype-phenotype correlations, varying inheritance patterns, hypomorphic alleles, and modifier genes thus complicating genetic interpretation. Next-generation sequencing has greatly advanced the identification of novel IRD-related genes and pathogenic variants in the last decade. For this review, we performed an in-depth literature search which allowed for compilation of the Global Retinal Inherited Disease (GRID) dataset containing 4,798 discrete variants and 17,299 alleles published in 31 papers, showing a wide range of frequencies and complexities among the 194 genes reported in GRID, with 65% of pathogenic variants being unique to a single individual. A better understanding of IRD-related gene distribution, gene complexity, and variant types allow for improved genetic testing and therapies. Current genetic therapeutic methods are also quite diverse and rely on variant identification, and range from whole gene replacement to single nucleotide editing at the DNA or RNA levels. IRDs and their suitable therapies thus require a range of effective disease modelling in human cells, granting insight into disease mechanisms and testing of possible treatments. This review summarizes genetic and therapeutic modalities of IRDs, provides new analyses of IRD-related genes (GRID and complexity scores), and provides information to match genetic-based therapies such as gene-specific and variant-specific therapies to the appropriate individuals.
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Affiliation(s)
- Nina Schneider
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel
| | - Yogapriya Sundaresan
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel
| | - Prakadeeswari Gopalakrishnan
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel
| | - Avigail Beryozkin
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel
| | - Mor Hanany
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel
| | - Erez Y Levanon
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, 5290002, Israel
| | - Eyal Banin
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel
| | - Shay Ben-Aroya
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, 5290002, Israel
| | - Dror Sharon
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel.
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12
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Piotter E, McClements ME, MacLaren RE. Therapy Approaches for Stargardt Disease. Biomolecules 2021; 11:1179. [PMID: 34439845 PMCID: PMC8393614 DOI: 10.3390/biom11081179] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 07/27/2021] [Accepted: 08/05/2021] [Indexed: 12/14/2022] Open
Abstract
Despite being the most prevalent cause of inherited blindness in children, Stargardt disease is yet to achieve the same clinical trial success as has been achieved for other inherited retinal diseases. With an early age of onset and continual progression of disease over the life course of an individual, Stargardt disease appears to lend itself to therapeutic intervention. However, the aetiology provides issues not encountered with the likes of choroideremia and X-linked retinitis pigmentosa and this has led to a spectrum of treatment strategies that approach the problem from different aspects. These include therapeutics ranging from small molecules and anti-sense oligonucleotides to viral gene supplementation and cell replacement. The advancing development of CRISPR-based molecular tools is also likely to contribute to future therapies by way of genome editing. In this we review, we consider the most recent pre-clinical and clinical trial data relating to the different strategies being applied to the problem of generating a treatment for the large cohort of Stargardt disease patients worldwide.
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Affiliation(s)
- Elena Piotter
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK; (E.P.); (M.E.M.)
- Oxford University Hospitals NHS Foundation Trust NIHR Biomedical Research Centre, Oxford OX3 9DU, UK
| | - Michelle E McClements
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK; (E.P.); (M.E.M.)
- Oxford University Hospitals NHS Foundation Trust NIHR Biomedical Research Centre, Oxford OX3 9DU, UK
| | - Robert E MacLaren
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK; (E.P.); (M.E.M.)
- Oxford University Hospitals NHS Foundation Trust NIHR Biomedical Research Centre, Oxford OX3 9DU, UK
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13
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Malik TN, Doherty EE, Gaded VM, Hill TM, Beal PA, Emeson RB. Regulation of RNA editing by intracellular acidification. Nucleic Acids Res 2021; 49:4020-4036. [PMID: 33721028 PMCID: PMC8053123 DOI: 10.1093/nar/gkab157] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 02/03/2021] [Accepted: 02/25/2021] [Indexed: 12/13/2022] Open
Abstract
The hydrolytic deamination of adenosine-to-inosine (A-to-I) by RNA editing is a widespread post-transcriptional modification catalyzed by the adenosine deaminase acting on RNA (ADAR) family of proteins. ADAR-mediated RNA editing modulates cellular pathways involved in innate immunity, RNA splicing, RNA interference, and protein recoding, and has been investigated as a strategy for therapeutic intervention of genetic disorders. Despite advances in basic and translational research, the mechanisms regulating RNA editing are poorly understood. Though several trans-acting regulators of editing have been shown to modulate ADAR protein expression, previous studies have not identified factors that modulate ADAR catalytic activity. Here, we show that RNA editing increases upon intracellular acidification, and that these effects are predominantly explained by both enhanced ADAR base-flipping and deamination rate at acidic pH. We also show that the extent of RNA editing increases with the reduction in pH associated with conditions of cellular hypoxia.
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Affiliation(s)
- Turnee N Malik
- Training Program in Neuroscience, Vanderbilt University, Nashville, TN 37232, USA
| | - Erin E Doherty
- Department of Chemistry, University of California, Davis, Davis, CA 95616, USA
| | - Vandana M Gaded
- Department of Chemistry, University of California, Davis, Davis, CA 95616, USA
| | - Theodore M Hill
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Peter A Beal
- Department of Chemistry, University of California, Davis, Davis, CA 95616, USA
| | - Ronald B Emeson
- Training Program in Neuroscience, Vanderbilt University, Nashville, TN 37232, USA.,Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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14
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Erdmann EA, Mahapatra A, Mukherjee P, Yang B, Hundley HA. To protect and modify double-stranded RNA - the critical roles of ADARs in development, immunity and oncogenesis. Crit Rev Biochem Mol Biol 2020; 56:54-87. [PMID: 33356612 DOI: 10.1080/10409238.2020.1856768] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Adenosine deaminases that act on RNA (ADARs) are present in all animals and function to both bind double-stranded RNA (dsRNA) and catalyze the deamination of adenosine (A) to inosine (I). As inosine is a biological mimic of guanosine, deamination by ADARs changes the genetic information in the RNA sequence and is commonly referred to as RNA editing. Millions of A-to-I editing events have been reported for metazoan transcriptomes, indicating that RNA editing is a widespread mechanism used to generate molecular and phenotypic diversity. Loss of ADARs results in lethality in mice and behavioral phenotypes in worm and fly model systems. Furthermore, alterations in RNA editing occur in over 35 human pathologies, including several neurological disorders, metabolic diseases, and cancers. In this review, a basic introduction to ADAR structure and target recognition will be provided before summarizing how ADARs affect the fate of cellular RNAs and how researchers are using this knowledge to engineer ADARs for personalized medicine. In addition, we will highlight the important roles of ADARs and RNA editing in innate immunity and cancer biology.
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Affiliation(s)
- Emily A Erdmann
- Department of Biology, Indiana University, Bloomington, IN, USA
| | | | - Priyanka Mukherjee
- Medical Sciences Program, Indiana University School of Medicine-Bloomington, Bloomington, IN, USA
| | - Boyoon Yang
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
| | - Heather A Hundley
- Medical Sciences Program, Indiana University School of Medicine-Bloomington, Bloomington, IN, USA
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15
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Teoh PJ, Koh MY, Chng WJ. ADARs, RNA editing and more in hematological malignancies. Leukemia 2020; 35:346-359. [PMID: 33139858 DOI: 10.1038/s41375-020-01076-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 08/21/2020] [Accepted: 10/20/2020] [Indexed: 02/08/2023]
Abstract
Adenosine-to-inosine (A-to-I) editing is the most prevalent type of RNA editing in humans, mediated by the adenosine deaminases acting on RNA (ADARs). Physiologically, these enzymes are present in the nucleus and/or the cytoplasm, where they catalyze the conversion of adenosines (A) to inosines (I) on double-stranded mRNA molecules. Aberrant ADAR-mediated-editing is a prominent feature in a variety of cancers. Importantly, the biological functions of ADARs and its functional implications in hematological malignancies have recently been unraveled. In this review, we will highlight the functions of ADARs and their involvements in cancer, specifically in hematological malignancies. RNA editing-independent function of cellular processes by ADARs and the potential of developing novel therapeutic approaches revolving RNA editing will also be discussed.
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Affiliation(s)
- Phaik Ju Teoh
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Cancer Science Institute of Singapore, Singapore, Singapore
| | - Mun Yee Koh
- Cancer Science Institute of Singapore, Singapore, Singapore
| | - Wee Joo Chng
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore. .,Cancer Science Institute of Singapore, Singapore, Singapore. .,Department of Haematology-Oncology, National University Cancer Institute of Singapore, National University Health System, Singapore, Singapore.
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16
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Ye C, Jiang S, Gong M, Min Q, Fan M, Gao J, Meng Y. Expressional Localization and Functionally Identifying an RNA Editing Enzyme BmADARa of the Silkworm Bombyx mori. INSECTS 2020; 11:insects11080523. [PMID: 32806497 PMCID: PMC7469206 DOI: 10.3390/insects11080523] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 08/04/2020] [Accepted: 08/07/2020] [Indexed: 11/16/2022]
Abstract
The most common type of RNA editing in metazoans is the deamination of adenosine into inosine (A-to-I) catalyzed by the adenosine deaminase acting on the RNA (ADAR) family of proteins. The deletion or dysfunction of ADAR enzymes in higher eukaryotes can affect the efficiency of substrate editing and cause neurological disorders. However, the information concerning A-to-I RNA editing and ADAR members in the silkworm, Bombyx mori (BmADAR), is limited. In this study, a first molecular comprehensive cloning and sequence analysis of BmADAR transcripts was presented. A complete open reading frame (ORF) (BmADARa) was obtained using RT-PCR and RACE and its expression pattern, subcellular localization and A-to-I RNA-editing function on the silkworm synaptotagmin I (BmSyt I) were investigated. Subcellular localization analysis observed that BmADARa was mainly localized in the nucleus. To further study the A-to-I RNA-editing function of BmADARa, BmSyt I-pIZ-EGFP was constructed and co-transfected with BmADARa-pIZ-EGFP into BmN cells. The result demonstrates that BmADARa can functionally edit the specific site of BmSyt I. Taken together, this study not only provides insight into the function of the first ADAR enzyme in B. mori, but also lays foundations for further exploration of the functional domain of BmADARa and its editing substrates and target sites.
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Affiliation(s)
- Chongjun Ye
- School of Life Sciences, Anhui Agricultural University, 130 West Changjiang Road, Hefei 230036, China; (C.Y.); (S.J.); (Q.M.); (M.F.)
- Institute of Sericulture, Anhui Academy of Agricultural Sciences, 15 Huoshan Road, Hefei 230061, China
| | - Song Jiang
- School of Life Sciences, Anhui Agricultural University, 130 West Changjiang Road, Hefei 230036, China; (C.Y.); (S.J.); (Q.M.); (M.F.)
- Anhui International Joint Research and Development Center of Sericulture Resources Utilization, Hefei 230036, China
| | - Meixia Gong
- Guangxi Zhuang Autonomous Region Research Academy of Sericultural Science, 10 Xiajun Road, Nanning 530007, China;
| | - Qin Min
- School of Life Sciences, Anhui Agricultural University, 130 West Changjiang Road, Hefei 230036, China; (C.Y.); (S.J.); (Q.M.); (M.F.)
| | - Manli Fan
- School of Life Sciences, Anhui Agricultural University, 130 West Changjiang Road, Hefei 230036, China; (C.Y.); (S.J.); (Q.M.); (M.F.)
| | - Junshan Gao
- School of Life Sciences, Anhui Agricultural University, 130 West Changjiang Road, Hefei 230036, China; (C.Y.); (S.J.); (Q.M.); (M.F.)
- Anhui International Joint Research and Development Center of Sericulture Resources Utilization, Hefei 230036, China
- Correspondence: (J.G.); (Y.M.); Tel.: +86-551-65786967 (Y.M.)
| | - Yan Meng
- School of Life Sciences, Anhui Agricultural University, 130 West Changjiang Road, Hefei 230036, China; (C.Y.); (S.J.); (Q.M.); (M.F.)
- Anhui International Joint Research and Development Center of Sericulture Resources Utilization, Hefei 230036, China
- Correspondence: (J.G.); (Y.M.); Tel.: +86-551-65786967 (Y.M.)
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17
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Nakahama T, Kawahara Y. Adenosine-to-inosine RNA editing in the immune system: friend or foe? Cell Mol Life Sci 2020; 77:2931-2948. [PMID: 31996954 PMCID: PMC11104962 DOI: 10.1007/s00018-020-03466-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 12/27/2019] [Accepted: 01/14/2020] [Indexed: 12/19/2022]
Abstract
Our body expresses sensors to detect pathogens through the recognition of expressed molecules, including nucleic acids, lipids, and proteins, while immune tolerance prevents an overreaction with self and the development of autoimmune disease. Adenosine (A)-to-inosine (I) RNA editing, catalyzed by adenosine deaminases acting on RNA (ADARs), is a post-transcriptional modification that can potentially occur at over 100 million sites in the human genome, mainly in Alu repetitive elements that preferentially form a double-stranded RNA (dsRNA) structure. A-to-I conversion within dsRNA, which may induce a structural change, is required to escape from the host immune system, given that endogenous dsRNAs transcribed from Alu repetitive elements are potentially recognized by melanoma differentiation-associated protein 5 (MDA5) as non-self. Of note, loss-of-function mutations in the ADAR1 gene cause Aicardi-Goutières syndrome, a congenital autoimmune disease characterized by encephalopathy and a type I interferon (IFN) signature. However, the loss of ADAR1 in cancer cells with an IFN signature induces lethality via the activation of protein kinase R in addition to MDA5. This makes cells more sensitive to immunotherapy, highlighting the opposing immune status of autoimmune diseases (overreaction) and cancer (tolerance). In this review, we provide an overview of insights into two opposing aspects of RNA editing that functions as a modulator of the immune system in autoimmune diseases and cancer.
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Affiliation(s)
- Taisuke Nakahama
- Department of RNA Biology and Neuroscience, Graduate School of Medicine, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Yukio Kawahara
- Department of RNA Biology and Neuroscience, Graduate School of Medicine, Osaka University, Suita, Osaka, 565-0871, Japan.
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18
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Vallecillo-Viejo IC, Liscovitch-Brauer N, Diaz Quiroz JF, Montiel-Gonzalez MF, Nemes SE, Rangan KJ, Levinson SR, Eisenberg E, Rosenthal JJC. Spatially regulated editing of genetic information within a neuron. Nucleic Acids Res 2020; 48:3999-4012. [PMID: 32201888 PMCID: PMC7192619 DOI: 10.1093/nar/gkaa172] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 02/14/2020] [Accepted: 03/11/2020] [Indexed: 12/11/2022] Open
Abstract
In eukaryotic cells, with the exception of the specialized genomes of mitochondria and plastids, all genetic information is sequestered within the nucleus. This arrangement imposes constraints on how the information can be tailored for different cellular regions, particularly in cells with complex morphologies like neurons. Although messenger RNAs (mRNAs), and the proteins that they encode, can be differentially sorted between cellular regions, the information itself does not change. RNA editing by adenosine deamination can alter the genome's blueprint by recoding mRNAs; however, this process too is thought to be restricted to the nucleus. In this work, we show that ADAR2 (adenosine deaminase that acts on RNA), an RNA editing enzyme, is expressed outside of the nucleus in squid neurons. Furthermore, purified axoplasm exhibits adenosine-to-inosine activity and can specifically edit adenosines in a known substrate. Finally, a transcriptome-wide analysis of RNA editing reveals that tens of thousands of editing sites (>70% of all sites) are edited more extensively in the squid giant axon than in its cell bodies. These results indicate that within a neuron RNA editing can recode genetic information in a region-specific manner.
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Affiliation(s)
| | - Noa Liscovitch-Brauer
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel
| | - Juan F Diaz Quiroz
- The Eugene Bell Center, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02540, USA
| | | | - Sonya E Nemes
- The Eugene Bell Center, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02540, USA
| | - Kavita J Rangan
- The Eugene Bell Center, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02540, USA
| | - Simon R Levinson
- Department of Physiology and Biophysics, University of Colorado at Denver, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Eli Eisenberg
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel
| | - Joshua J C Rosenthal
- The Eugene Bell Center, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02540, USA
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19
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Moore S, Rabichow BE, Sattler R. The Hitchhiker's Guide to Nucleocytoplasmic Trafficking in Neurodegeneration. Neurochem Res 2020; 45:1306-1327. [PMID: 32086712 DOI: 10.1007/s11064-020-02989-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 02/12/2020] [Accepted: 02/14/2020] [Indexed: 12/12/2022]
Abstract
The widespread nature of nucleocytoplasmic trafficking defects and protein accumulation suggests distinct yet overlapping mechanisms in a variety of neurodegenerative diseases. Detailed understanding of the cellular pathways involved in nucleocytoplasmic transport and its dysregulation are essential for elucidating neurodegenerative pathogenesis and pinpointing potential areas for therapeutic intervention. The transport of cargos from the nucleus to the cytoplasm is generally regulated by the structure and function of the nuclear pore as well as the karyopherin α/β, importin, exportin, and mRNA export mechanisms. The disruption of these crucial transport mechanisms has been extensively described in the context of neurodegenerative diseases. One common theme in neurodegeneration is the cytoplasmic aggregation of proteins, including nuclear RNA binding proteins, repeat expansion associated gene products, and tau. These cytoplasmic aggregations are partly a consequence of failed nucleocytoplasmic transport machinery, but can also further disrupt transport, creating cyclical feed-forward mechanisms that exacerbate neurodegeneration. Here we describe the canonical mechanisms that regulate nucleocytoplasmic trafficking as well as how these mechanisms falter in neurodegenerative diseases.
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Affiliation(s)
- Stephen Moore
- Department of Neurobiology, Barrow Neurological Institute, 350 W Thomas Road, Phoenix, AZ, 85013, USA.,School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - Benjamin E Rabichow
- Department of Neurobiology, Barrow Neurological Institute, 350 W Thomas Road, Phoenix, AZ, 85013, USA
| | - Rita Sattler
- Department of Neurobiology, Barrow Neurological Institute, 350 W Thomas Road, Phoenix, AZ, 85013, USA.
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20
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Fry LE, Peddle CF, Barnard AR, McClements ME, MacLaren RE. RNA editing as a therapeutic approach for retinal gene therapy requiring long coding sequences. Int J Mol Sci 2020; 21:ijms21030777. [PMID: 31991730 PMCID: PMC7037314 DOI: 10.3390/ijms21030777] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 01/20/2020] [Accepted: 01/21/2020] [Indexed: 12/26/2022] Open
Abstract
RNA editing aims to treat genetic disease through altering gene expression at the transcript level. Pairing site-directed RNA-targeting mechanisms with engineered deaminase enzymes allows for the programmable correction of G>A and T>C mutations in RNA. This offers a promising therapeutic approach for a range of genetic diseases. For inherited retinal degenerations caused by point mutations in large genes not amenable to single-adeno-associated viral (AAV) gene therapy such as USH2A and ABCA4, correcting RNA offers an alternative to gene replacement. Genome editing of RNA rather than DNA may offer an improved safety profile, due to the transient and potentially reversible nature of edits made to RNA. This review considers the current site-directing RNA editing systems, and the potential to translate these to the clinic for the treatment of inherited retinal degeneration.
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Affiliation(s)
- Lewis E. Fry
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
- Correspondence:
| | - Caroline F. Peddle
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
| | - Alun R. Barnard
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
| | - Michelle E. McClements
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
| | - Robert E. MacLaren
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
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21
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Shanmugam R, Zhang F, Srinivasan H, Charles Richard JL, Liu KI, Zhang X, Woo CWA, Chua ZHM, Buschdorf JP, Meaney MJ, Tan MH. SRSF9 selectively represses ADAR2-mediated editing of brain-specific sites in primates. Nucleic Acids Res 2019; 46:7379-7395. [PMID: 29992293 PMCID: PMC6101530 DOI: 10.1093/nar/gky615] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 06/26/2018] [Indexed: 02/05/2023] Open
Abstract
Adenosine-to-inosine (A-to-I) RNA editing displays diverse spatial patterns across different tissues. However, the human genome encodes only two catalytically active editing enzymes (ADAR1 and ADAR2), suggesting that other regulatory factors help shape the editing landscape. Here, we show that the splicing factor SRSF9 selectively controls the editing of many brain-specific sites in primates. SRSF9 is more lowly expressed in the brain than in non-brain tissues. Gene perturbation experiments and minigene analysis of candidate sites demonstrated that SRSF9 could robustly repress A-to-I editing by ADAR2. We found that SRSF9 biochemically interacted with ADAR2 in the nucleus via its RRM2 domain. This interaction required the presence of the RNA substrate and disrupted the formation of ADAR2 dimers. Transcriptome-wide location analysis and RNA sequencing revealed 1328 editing sites that are controlled directly by SRSF9. This regulon is significantly enriched for brain-specific sites. We further uncovered a novel motif in the ADAR2-dependent SRSF9 binding sites and provided evidence that the splicing factor prevents loss of cell viability by inhibiting ADAR2-mediated editing of genes involved in proteostasis, energy metabolism, the cell cycle and DNA repair. Collectively, our results highlight the importance of SRSF9 as an editing regulator and suggest potential roles for other splicing factors.
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Affiliation(s)
- Raghuvaran Shanmugam
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459, Singapore.,Genome Institute of Singapore, Agency for Science Technology and Research, Singapore 138672, Singapore
| | - Fan Zhang
- Genome Institute of Singapore, Agency for Science Technology and Research, Singapore 138672, Singapore
| | - Harini Srinivasan
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459, Singapore.,Genome Institute of Singapore, Agency for Science Technology and Research, Singapore 138672, Singapore
| | | | - Kaiwen I Liu
- Genome Institute of Singapore, Agency for Science Technology and Research, Singapore 138672, Singapore
| | - Xiujun Zhang
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459, Singapore.,Genome Institute of Singapore, Agency for Science Technology and Research, Singapore 138672, Singapore
| | - Cheok Wei A Woo
- Genome Institute of Singapore, Agency for Science Technology and Research, Singapore 138672, Singapore
| | - Zi Hao M Chua
- Genome Institute of Singapore, Agency for Science Technology and Research, Singapore 138672, Singapore.,School of Life Sciences and Chemical Technology, Ngee Ann Polytechnic, Singapore 599489, Singapore
| | - Jan Paul Buschdorf
- Singapore Institute for Clinical Sciences, Agency for Science Technology and Research, Singapore 117609, Singapore
| | - Michael J Meaney
- Singapore Institute for Clinical Sciences, Agency for Science Technology and Research, Singapore 117609, Singapore.,Douglas Mental Health University Institute, McGill University, Montreal (Quebec) H4H 1R3, Canada
| | - Meng How Tan
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459, Singapore.,Genome Institute of Singapore, Agency for Science Technology and Research, Singapore 138672, Singapore
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22
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Sinigaglia K, Wiatrek D, Khan A, Michalik D, Sambrani N, Sedmík J, Vukić D, O'Connell MA, Keegan LP. ADAR RNA editing in innate immune response phasing, in circadian clocks and in sleep. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2019; 1862:356-369. [DOI: 10.1016/j.bbagrm.2018.10.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 10/12/2018] [Accepted: 10/27/2018] [Indexed: 01/24/2023]
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23
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Abstract
Noncoding RNAs (ncRNAs) have received much attention due to their central role in gene expression and translational regulation as well as due to their involvement in several biological processes and disease development. Small noncoding RNAs (sncRNAs), such as microRNAs and piwiRNAs, have been thoroughly investigated and functionally characterized. Long noncoding RNAs (lncRNAs), known to play an important role in chromatin-interacting transcription regulation, posttranscriptional regulation, cell-to-cell signaling, and protein regulation, are also being investigated to further elucidate their functional roles.Next-generation sequencing (NGS) technologies have greatly aided in characterizing the ncRNAome. Moreover, the coupling of NGS technology together with bioinformatics tools has been essential to the genome-wide detection of RNA modifications in ncRNAs. RNA editing, a common human co-transcriptional and posttranscriptional modification, is a dynamic biological phenomenon able to alter the sequence and the structure of primary transcripts (both coding and noncoding RNAs) during the maturation process, consequently influencing the biogenesis, as well as the function, of ncRNAs. In particular, the dysregulation of the RNA editing machineries have been associated with the onset of human diseases.In this chapter we discuss the potential functions of ncRNA editing and describe the knowledge base and bioinformatics resources available to investigate such phenomenon.
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24
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Shevchenko G, Morris KV. All I's on the RADAR: role of ADAR in gene regulation. FEBS Lett 2018; 592:2860-2873. [PMID: 29770436 DOI: 10.1002/1873-3468.13093] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 04/26/2018] [Accepted: 05/05/2018] [Indexed: 12/12/2022]
Abstract
Adenosine to inosine (A-to-I) editing is the most abundant form of RNA modification in mammalian cells, which is catalyzed by adenosine deaminase acting on the double-stranded RNA (ADAR) protein family. A-to-I editing is currently known to be involved in the regulation of the immune system, RNA splicing, protein recoding, microRNA biogenesis, and formation of heterochromatin. Editing occurs within regions of double-stranded RNA, particularly within inverted Alu repeats, and is associated with many diseases including cancer, neurological disorders, and metabolic syndromes. However, the significance of RNA editing in a large portion of the transcriptome remains unknown. Here, we review the current knowledge about the prevalence and function of A-to-I editing by the ADAR protein family, focusing on its role in the regulation of gene expression. Furthermore, RNA editing-independent regulation of cellular processes by ADAR and the putative role(s) of this process in gene regulation will be discussed.
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Affiliation(s)
- Galina Shevchenko
- Hematological Malignancy and Stem Cell Transplantation Institute, Center for Gene Therapy, City of Hope-Beckman Research Institute, Duarte, CA, USA
| | - Kevin V Morris
- Hematological Malignancy and Stem Cell Transplantation Institute, Center for Gene Therapy, City of Hope-Beckman Research Institute, Duarte, CA, USA
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25
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Mladenova D, Barry G, Konen LM, Pineda SS, Guennewig B, Avesson L, Zinn R, Schonrock N, Bitar M, Jonkhout N, Crumlish L, Kaczorowski DC, Gong A, Pinese M, Franco GR, Walkley CR, Vissel B, Mattick JS. Adar3 Is Involved in Learning and Memory in Mice. Front Neurosci 2018; 12:243. [PMID: 29719497 PMCID: PMC5914295 DOI: 10.3389/fnins.2018.00243] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 03/27/2018] [Indexed: 11/13/2022] Open
Abstract
The amount of regulatory RNA encoded in the genome and the extent of RNA editing by the post-transcriptional deamination of adenosine to inosine (A-I) have increased with developmental complexity and may be an important factor in the cognitive evolution of animals. The newest member of the A-I editing family of ADAR proteins, the vertebrate-specific ADAR3, is highly expressed in the brain, but its functional significance is unknown. In vitro studies have suggested that ADAR3 acts as a negative regulator of A-I RNA editing but the scope and underlying mechanisms are also unknown. Meta-analysis of published data indicates that mouse Adar3 expression is highest in the hippocampus, thalamus, amygdala, and olfactory region. Consistent with this, we show that mice lacking exon 3 of Adar3 (which encodes two double stranded RNA binding domains) have increased levels of anxiety and deficits in hippocampus-dependent short- and long-term memory formation. RNA sequencing revealed a dysregulation of genes involved in synaptic function in the hippocampi of Adar3-deficient mice. We also show that ADAR3 transiently translocates from the cytoplasm to the nucleus upon KCl-mediated activation in SH-SY5Y cells. These results indicate that ADAR3 contributes to cognitive processes in mammals.
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Affiliation(s)
- Dessislava Mladenova
- Garvan Institute of Medical Research, Sydney, NSW, Australia
- St. Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - Guy Barry
- Garvan Institute of Medical Research, Sydney, NSW, Australia
- St. Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - Lyndsey M. Konen
- Garvan Institute of Medical Research, Sydney, NSW, Australia
- Centre for Neuroscience and Regenerative Medicine, Faculty of Science, University of Technology Sydney, Sydney, NSW, Australia
- St. Vincent's Centre for Applied Medical Research (AMR), Sydney, NSW, Australia
| | - Sandy S. Pineda
- Garvan Institute of Medical Research, Sydney, NSW, Australia
- St. Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - Boris Guennewig
- Garvan Institute of Medical Research, Sydney, NSW, Australia
- St. Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - Lotta Avesson
- Garvan Institute of Medical Research, Sydney, NSW, Australia
| | - Raphael Zinn
- Garvan Institute of Medical Research, Sydney, NSW, Australia
- Centre for Neuroscience and Regenerative Medicine, Faculty of Science, University of Technology Sydney, Sydney, NSW, Australia
- St. Vincent's Centre for Applied Medical Research (AMR), Sydney, NSW, Australia
| | - Nicole Schonrock
- Garvan Institute of Medical Research, Sydney, NSW, Australia
- St. Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - Maina Bitar
- Garvan Institute of Medical Research, Sydney, NSW, Australia
- St. Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - Nicky Jonkhout
- Garvan Institute of Medical Research, Sydney, NSW, Australia
- St. Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - Lauren Crumlish
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD, Australia
| | | | - Andrew Gong
- Garvan Institute of Medical Research, Sydney, NSW, Australia
| | - Mark Pinese
- Garvan Institute of Medical Research, Sydney, NSW, Australia
- St. Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - Gloria R. Franco
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Carl R. Walkley
- St. Vincent's Institute of Medical Research, Department of Medicine, St. Vincent's Hospital, The University of Melbourne, Fitzroy, VIC, Australia
| | - Bryce Vissel
- Garvan Institute of Medical Research, Sydney, NSW, Australia
- Centre for Neuroscience and Regenerative Medicine, Faculty of Science, University of Technology Sydney, Sydney, NSW, Australia
- St. Vincent's Centre for Applied Medical Research (AMR), Sydney, NSW, Australia
| | - John S. Mattick
- Garvan Institute of Medical Research, Sydney, NSW, Australia
- St. Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia
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Filippini A, Bonini D, Giacopuzzi E, La Via L, Gangemi F, Colombi M, Barbon A. Differential Enzymatic Activity of Rat ADAR2 Splicing Variants Is Due to Altered Capability to Interact with RNA in the Deaminase Domain. Genes (Basel) 2018; 9:genes9020079. [PMID: 29419780 PMCID: PMC5852575 DOI: 10.3390/genes9020079] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 01/19/2018] [Accepted: 01/19/2018] [Indexed: 12/17/2022] Open
Abstract
In mammals, adenosine (A) to inosine (I) RNA editing is performed by adenosine deaminases acting on RNA (ADAR), ADAR1 and ADAR2 enzymes, encoded by mRNAs that might undergo splicing process. In rat, two splicing events produce several isoforms of ADAR2, called ADAR2a, ADAR2b, ADAR2e, and ADAR2f, but only ADAR2a and ADAR2b are translated into an active protein. In particular, they differ for ten amino acids located in the catalytic domain of ADAR2b. Here, we focused on these two isoforms, analyzing the splicing pattern and their different function during rat neuronal maturation. We found an increase of editing levels in cortical neurons overexpressing ADAR2a compared to those overexpressing ADAR2b. These results indicate ADAR2a isoform as the most active one, as reported for the homologous human short variant. Furthermore, we showed that the differential editing activity is not due to a different dimerization of the two isoforms; it seems to be linked to the ten amino acids loop of ADAR2b that might interfere with RNA binding, occupying the space volume in which the RNA should be present in case of binding. These data might shed light on the complexity of ADAR2 regulations.
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Affiliation(s)
- Alice Filippini
- Division of Biology and Genetics-Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy.
| | - Daniela Bonini
- Division of Biology and Genetics-Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy.
| | - Edoardo Giacopuzzi
- Division of Biology and Genetics-Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy.
| | - Luca La Via
- Division of Biology and Genetics-Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy.
| | - Fabrizio Gangemi
- Division of Physics, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy.
| | - Marina Colombi
- Division of Biology and Genetics-Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy.
| | - Alessandro Barbon
- Division of Biology and Genetics-Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy.
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27
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Vallecillo-Viejo IC, Liscovitch-Brauer N, Montiel-Gonzalez MF, Eisenberg E, Rosenthal JJC. Abundant off-target edits from site-directed RNA editing can be reduced by nuclear localization of the editing enzyme. RNA Biol 2018; 15:104-114. [PMID: 29099293 PMCID: PMC5786015 DOI: 10.1080/15476286.2017.1387711] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 09/28/2017] [Indexed: 02/06/2023] Open
Abstract
Site-directed RNA editing (SDRE) is a general strategy for making targeted base changes in RNA molecules. Although the approach is relatively new, several groups, including our own, have been working on its development. The basic strategy has been to couple the catalytic domain of an adenosine (A) to inosine (I) RNA editing enzyme to a guide RNA that is used for targeting. Although highly efficient on-target editing has been reported, off-target events have not been rigorously quantified. In this report we target premature termination codons (PTCs) in messages encoding both a fluorescent reporter protein and the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein transiently transfected into human epithelial cells. We demonstrate that while on-target editing is efficient, off-target editing is extensive, both within the targeted message and across the entire transcriptome of the transfected cells. By redirecting the editing enzymes from the cytoplasm to the nucleus, off-target editing is reduced without compromising the on-target editing efficiency. The addition of the E488Q mutation to the editing enzymes, a common strategy for increasing on-target editing efficiency, causes a tremendous increase in off-target editing. These results underscore the need to reduce promiscuity in current approaches to SDRE.
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Affiliation(s)
- Isabel C. Vallecillo-Viejo
- Eugene Bell Center for Regenerative Biology and Tissue Engineering, The Marine Biological Laboratory, Woods Hole, MA, USA
- Department of Medicine, University of Puerto Rico, Medical Sciences Campus, San Juan, Puerto Rico
| | - Noa Liscovitch-Brauer
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel
| | | | - Eli Eisenberg
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel
| | - Joshua J. C. Rosenthal
- Eugene Bell Center for Regenerative Biology and Tissue Engineering, The Marine Biological Laboratory, Woods Hole, MA, USA
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28
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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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29
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Reprint of: Importins in the maintenance and lineage commitment of ES cells. Neurochem Int 2017; 106:14-23. [PMID: 28550879 DOI: 10.1016/j.neuint.2017.01.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 01/25/2017] [Accepted: 01/30/2017] [Indexed: 11/23/2022]
Abstract
The nucleus of a eukaryotic cell is separated from the cytoplasm by a nuclear envelope, and nuclear pores within the envelope facilitate nucleocytoplasmic transport and the exchange of information. Gene regulation is a key component of biological activity regulation in the cell. Transcription factors control the expression levels of various genes that are necessary for the maintenance or conversion of cellular states during animal development. Because transcription factor activities determine the extent of transcription of target genes, the number of active transcription factors must be tightly regulated. In this regard, the nuclear translocation of a transcription factor is an important determinant of its activity. Therefore, it is becoming clear that the nucleocytoplasmic transport machinery is involved in cell differentiation and organism development. This review examines the regulation of transcription factors by the nucleocytoplasmic transport machinery in ES cells.
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30
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Importins in the maintenance and lineage commitment of ES cells. Neurochem Int 2017; 105:32-41. [PMID: 28163061 DOI: 10.1016/j.neuint.2017.01.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 01/25/2017] [Accepted: 01/30/2017] [Indexed: 11/23/2022]
Abstract
The nucleus of a eukaryotic cell is separated from the cytoplasm by a nuclear envelope, and nuclear pores within the envelope facilitate nucleocytoplasmic transport and the exchange of information. Gene regulation is a key component of biological activity regulation in the cell. Transcription factors control the expression levels of various genes that are necessary for the maintenance or conversion of cellular states during animal development. Because transcription factor activities determine the extent of transcription of target genes, the number of active transcription factors must be tightly regulated. In this regard, the nuclear translocation of a transcription factor is an important determinant of its activity. Therefore, it is becoming clear that the nucleocytoplasmic transport machinery is involved in cell differentiation and organism development. This review examines the regulation of transcription factors by the nucleocytoplasmic transport machinery in ES cells.
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31
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Behm M, Wahlstedt H, Widmark A, Eriksson M, Öhman M. Accumulation of nuclear ADAR2 regulates adenosine-to-inosine RNA editing during neuronal development. J Cell Sci 2017; 130:745-753. [PMID: 28082424 DOI: 10.1242/jcs.200055] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 12/30/2016] [Indexed: 12/16/2022] Open
Abstract
Adenosine to inosine (A-to-I) RNA editing is important for a functional brain, and most known sites that are subject to selective RNA editing have been found to result in diversified protein isoforms that are involved in neurotransmission. In the absence of the active editing enzymes ADAR1 or ADAR2 (also known as ADAR and ADARB1, respectively), mice fail to survive until adulthood. Nuclear A-to-I editing of neuronal transcripts is regulated during brain development, with low levels of editing in the embryo and a dramatic increase after birth. Yet, little is known about the mechanisms that regulate editing during development. Here, we demonstrate lower levels of ADAR2 in the nucleus of immature neurons than in mature neurons. We show that importin-α4 (encoded by Kpna3), which increases during neuronal maturation, interacts with ADAR2 and contributes to the editing efficiency by bringing it into the nucleus. Moreover, we detect an increased number of interactions between ADAR2 and the nuclear isomerase Pin1 as neurons mature, which contribute to ADAR2 protein stability. Together, these findings explain how the nuclear editing of substrates that are important for neuronal function can increase as the brain develops.
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Affiliation(s)
- Mikaela Behm
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, Stockholm, 106 91, Sweden
| | - Helene Wahlstedt
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, Stockholm, 106 91, Sweden
| | - Albin Widmark
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, Stockholm, 106 91, Sweden
| | - Maria Eriksson
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, Stockholm, 106 91, Sweden
| | - Marie Öhman
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, Stockholm, 106 91, Sweden
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32
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Abstract
Adenosine deaminases acting on RNA (ADARs) convert adenosine to inosine in double-stranded RNA. This A-to-I editing occurs not only in protein-coding regions of mRNAs, but also frequently in non-coding regions that contain inverted Alu repeats. Editing of coding sequences can result in the expression of functionally altered proteins that are not encoded in the genome, whereas the significance of Alu editing remains largely unknown. Certain microRNA (miRNA) precursors are also edited, leading to reduced expression or altered function of mature miRNAs. Conversely, recent studies indicate that ADAR1 forms a complex with Dicer to promote miRNA processing, revealing a new function of ADAR1 in the regulation of RNA interference.
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33
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Mannion N, Arieti F, Gallo A, Keegan LP, O'Connell MA. New Insights into the Biological Role of Mammalian ADARs; the RNA Editing Proteins. Biomolecules 2015; 5:2338-62. [PMID: 26437436 PMCID: PMC4693238 DOI: 10.3390/biom5042338] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 09/09/2015] [Accepted: 09/11/2015] [Indexed: 12/20/2022] Open
Abstract
The ADAR proteins deaminate adenosine to inosine in double-stranded RNA which is one of the most abundant modifications present in mammalian RNA. Inosine can have a profound effect on the RNAs that are edited, not only changing the base-pairing properties, but can also result in recoding, as inosine behaves as if it were guanosine. In mammals there are three ADAR proteins and two ADAR-related proteins (ADAD) expressed. All have a very similar modular structure; however, both their expression and biological function differ significantly. Only two of the ADAR proteins have enzymatic activity. However, both ADAR and ADAD proteins possess the ability to bind double-strand RNA. Mutations in ADARs have been associated with many diseases ranging from cancer, innate immunity to neurological disorders. Here, we will discuss in detail the domain structure of mammalian ADARs, the effects of RNA editing, and the role of ADARs in human diseases.
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Affiliation(s)
- Niamh Mannion
- Paul O'Gorman Leukaemia Research Centre, Institute of Cancer Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, 21 Shelley Road, Glasgow G12 0ZD, UK.
| | - Fabiana Arieti
- CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 5, Brno 625 00, Czech Republic.
| | - Angela Gallo
- Oncohaematoogy Department, Ospedale Pediatrico Bambino Gesù (IRCCS) Viale di San Paolo, Roma 15-00146, Italy.
| | - Liam P Keegan
- CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 5, Brno 625 00, Czech Republic.
| | - Mary A O'Connell
- CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 5, Brno 625 00, Czech Republic.
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34
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Abstract
The human genome encodes seven isoforms of importin α which are grouped into three subfamilies known as α1, α2 and α3. All isoforms share a fundamentally conserved architecture that consists of an N-terminal, autoinhibitory, importin-β-binding (IBB) domain and a C-terminal Arm (Armadillo)-core that associates with nuclear localization signal (NLS) cargoes. Despite striking similarity in amino acid sequence and 3D structure, importin-α isoforms display remarkable substrate specificity in vivo. In the present review, we look at key differences among importin-α isoforms and provide a comprehensive inventory of known viral and cellular cargoes that have been shown to associate preferentially with specific isoforms. We illustrate how the diversification of the adaptor importin α into seven isoforms expands the dynamic range and regulatory control of nucleocytoplasmic transport, offering unexpected opportunities for pharmacological intervention. The emerging view of importin α is that of a key signalling molecule, with isoforms that confer preferential nuclear entry and spatiotemporal specificity on viral and cellular cargoes directly linked to human diseases.
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35
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Abstract
Adenosine-to-inosine (A-to-I) RNA editing, the most prevalent mode of transcript modification in higher eukaryotes, is catalysed by the adenosine deaminases acting on RNA (ADARs). A-to-I editing imposes an additional layer of gene regulation as it dictates various aspects of RNA metabolism, including RNA folding, processing, localization and degradation. Furthermore, editing events in exonic regions contribute to proteome diversity as translational machinery decodes inosine as guanosine. Although it has been demonstrated that dysregulated A-to-I editing contributes to various diseases, the precise regulatory mechanisms governing this critical cellular process have yet to be fully elucidated. However, integration of previous studies revealed that regulation of A-to-I editing is multifaceted, weaving an intricate network of auto- and transregulations, including the involvement of virus-originated factors like adenovirus-associated RNA. Taken together, it is apparent that tipping of any regulatory components will have profound effects on A-to-I editing, which in turn contributes to both normal and aberrant physiological conditions. A complete understanding of this intricate regulatory network may ultimately be translated into new therapeutic strategies against diseases driven by perturbed RNA editing events. Herein, we review the current state of knowledge on the regulatory mechanisms governing A-to-I editing and propose the role of other co-factors that may be involved in this complex regulatory process. This review discusses the current state of knowledge on the mechanisms adopted in regulation of Adenosine-to-Inosine RNA editing.
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36
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Major AT, Hogarth CA, Miyamoto Y, Sarraj MA, Smith CL, Koopman P, Kurihara Y, Jans DA, Loveland KL. Specific interaction with the nuclear transporter importin α2 can modulate paraspeckle protein 1 delivery to nuclear paraspeckles. Mol Biol Cell 2015; 26:1543-58. [PMID: 25694451 PMCID: PMC4395133 DOI: 10.1091/mbc.e14-01-0678] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Accepted: 02/12/2015] [Indexed: 12/12/2022] Open
Abstract
Paraspeckle protein 1 (PSPC1), a component of nuclear paraspeckles, is identified as an importin α2 (IMPα2) binding partner in mouse spermatogenic cells. PSPC1-IMPα2 binding modulates PSPC1 delivery to paraspeckles, highlighting the potential for regulated importin synthesis to direct RNA metabolism and cellular differentiation. Importin (IMP) superfamily members mediate regulated nucleocytoplasmic transport, which is central to key cellular processes. Although individual IMPα proteins exhibit dynamic synthesis and subcellular localization during cellular differentiation, including during spermatogenesis, little is known of how this affects cell fate. To investigate how IMPαs control cellular development, we conducted a yeast two-hybrid screen for IMPα2 cargoes in embryonic day 12.5 mouse testis, a site of peak IMPα2 expression coincident with germ-line masculization. We identified paraspeckle protein 1 (PSPC1), the original defining component of nuclear paraspeckles, as an IMPα2-binding partner. PSPC1-IMPα2 binding in testis was confirmed in immunoprecipitations and pull downs, and an enzyme-linked immunosorbent assay–based assay demonstrated direct, high-affinity PSPC1 binding to either IMPα2/IMPβ1 or IMPα6/IMPβ1. Coexpression of full-length PSPC1 and IMPα2 in HeLa cells yielded increased PSPC1 localization in nuclear paraspeckles. High-throughput image analysis of >3500 cells indicated IMPα2 levels can directly determine PSPC1-positive nuclear speckle numbers and size; a transport-deficient IMPα2 isoform or small interfering RNA knockdown of IMPα2 each reduced endogenous PSPC1 accumulation in speckles. This first validation of an IMPα2 nuclear import cargo in fetal testis provides novel evidence that PSPC1 delivery to paraspeckles, and consequently paraspeckle function, may be controlled by modulated synthesis of specific IMPs.
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Affiliation(s)
- Andrew T Major
- Department of Anatomy and Developmental Biology, Monash University, Melbourne, VIC 3800, Australia ARC Centre of Excellence in Biotechnology and Development, Australia
| | - Cathryn A Hogarth
- Center for Reproductive Biology and School of Molecular Biosciences, Washington State University, Pullman, WA 99163
| | - Yoichi Miyamoto
- ARC Centre of Excellence in Biotechnology and Development, Australia Department of Biochemistry and Molecular Biology, Monash University, Melbourne, VIC 3800, Australia
| | - Mai A Sarraj
- ARC Centre of Excellence in Biotechnology and Development, Australia MIMR-PHI Institute of Medical Research, Monash Health Translation Precinct, Clayton, VIC 3168, Australia
| | - Catherine L Smith
- Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC 3004, Australia
| | - Peter Koopman
- ARC Centre of Excellence in Biotechnology and Development, Australia Institute for Molecular Bioscience, University of Queensland, Brisbane, QLD 4072, Australia
| | - Yasuyuki Kurihara
- Faculty of Engineering Science, Yokohama National University, Yokohama 2408501, Japan
| | - David A Jans
- ARC Centre of Excellence in Biotechnology and Development, Australia Department of Biochemistry and Molecular Biology, Monash University, Melbourne, VIC 3800, Australia
| | - Kate L Loveland
- Department of Anatomy and Developmental Biology, Monash University, Melbourne, VIC 3800, Australia ARC Centre of Excellence in Biotechnology and Development, Australia Department of Biochemistry and Molecular Biology, Monash University, Melbourne, VIC 3800, Australia School of Clinical Sciences, Monash Health Translation Precinct, Monash University, Clayton, VIC 3168, Australia
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37
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ADAR enzyme and miRNA story: a nucleotide that can make the difference. Int J Mol Sci 2013; 14:22796-816. [PMID: 24256817 PMCID: PMC3856091 DOI: 10.3390/ijms141122796] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 11/04/2013] [Accepted: 11/05/2013] [Indexed: 12/21/2022] Open
Abstract
Adenosine deaminase acting on RNA (ADAR) enzymes convert adenosine (A) to inosine (I) in double-stranded (ds) RNAs. Since Inosine is read as Guanosine, the biological consequence of ADAR enzyme activity is an A/G conversion within RNA molecules. A-to-I editing events can occur on both coding and non-coding RNAs, including microRNAs (miRNAs), which are small regulatory RNAs of ~20–23 nucleotides that regulate several cell processes by annealing to target mRNAs and inhibiting their translation. Both miRNA precursors and mature miRNAs undergo A-to-I RNA editing, affecting the miRNA maturation process and activity. ADARs can also edit 3′ UTR of mRNAs, further increasing the interplay between mRNA targets and miRNAs. In this review, we provide a general overview of the ADAR enzymes and their mechanisms of action as well as miRNA processing and function. We then review the more recent findings about the impact of ADAR-mediated activity on the miRNA pathway in terms of biogenesis, target recognition, and gene expression regulation.
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38
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Grigera F, Bellacosa A, Kenter AL. Complex relationship between mismatch repair proteins and MBD4 during immunoglobulin class switch recombination. PLoS One 2013; 8:e78370. [PMID: 24205214 PMCID: PMC3812156 DOI: 10.1371/journal.pone.0078370] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 09/19/2013] [Indexed: 11/19/2022] Open
Abstract
Mismatch repair (MMR) safeguards against genomic instability and is required for efficient Ig class switch recombination (CSR). Methyl CpG binding domain protein 4 (MBD4) binds to MutL homologue 1 (MLH1) and controls the post-transcriptional level of several MMR proteins, including MutS homologue 2 (MSH2). We show that in WT B cells activated for CSR, MBD4 is induced and interacts with MMR proteins, thereby implying a role for MBD4 in CSR. However, CSR is in the normal range in Mbd4 deficient mice deleted for exons 2–5 despite concomitant reduction of MSH2. We show by comparison in Msh2+/− B cells that a two-fold reduction of MSH2 and MBD4 proteins is correlated with impaired CSR. It is therefore surprising that CSR occurs at normal frequencies in the Mbd4 deficient B cells where MSH2 is reduced. We find that a variant Mbd4 transcript spanning exons 1,6–8 is expressed in Mbd4 deficient B cells. This transcript can be ectopically expressed and produces a truncated MBD4 peptide. Thus, the 3′ end of the Mbd4 locus is not silent in Mbd4 deficient B cells and may contribute to CSR. Our findings highlight a complex relationship between MBD4 and MMR proteins in B cells and a potential reconsideration of their role in CSR.
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Affiliation(s)
- Fernando Grigera
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, Illinois, United States of America
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39
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Clingman CC, Ryder SP. Metabolite sensing in eukaryotic mRNA biology. WILEY INTERDISCIPLINARY REVIEWS-RNA 2013; 4:387-96. [PMID: 23653333 DOI: 10.1002/wrna.1167] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Revised: 03/22/2013] [Accepted: 03/22/2013] [Indexed: 01/16/2023]
Abstract
All living creatures change their gene expression program in response to nutrient availability and metabolic demands. Nutrients and metabolites can directly control transcription and activate second-messenger systems. More recent studies reveal that metabolites also affect post-transcriptional regulatory mechanisms. Here, we review the increasing number of connections between metabolism and post-transcriptional regulation in eukaryotic organisms. First, we present evidence that riboswitches, a common mechanism of metabolite sensing in bacteria, also function in eukaryotes. Next, we review an example of a double stranded RNA modifying enzyme that directly interacts with a metabolite, suggesting a link between RNA editing and metabolic state. Finally, we discuss work that shows some metabolic enzymes bind directly to RNA to affect mRNA stability or translation efficiency. These examples were discovered through gene-specific genetic, biochemical, and structural studies. A directed systems level approach will be necessary to determine whether they are anomalies of evolution or pioneer discoveries in what may be a broadly connected network of metabolism and post-transcriptional regulation.
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Affiliation(s)
- Carina C Clingman
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA
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40
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41
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Christiansen A, Dyrskjøt L. The functional role of the novel biomarker karyopherin α 2 (KPNA2) in cancer. Cancer Lett 2012; 331:18-23. [PMID: 23268335 PMCID: PMC7126488 DOI: 10.1016/j.canlet.2012.12.013] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Revised: 12/11/2012] [Accepted: 12/14/2012] [Indexed: 12/23/2022]
Abstract
In recent years, Karyopherin α 2 (KPNA2) has emerged as a potential biomarker in multiple cancer forms. The aberrant high levels observed in cancer tissue have been associated with adverse patient characteristics, prompting the idea that KPNA2 plays a role in carcinogenesis. This notion is supported by studies in cancer cells, where KPNA2 deregulation has been demonstrated to affect malignant transformation. By virtue of its role in nucleocytoplasmic transport, KPNA2 is implicated in the translocation of several cancer-associated proteins. We provide an overview of the clinical studies that have established the biomarker potential of KPNA2 and describe its functional role with an emphasis on established associations with cancer.
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Affiliation(s)
- Anders Christiansen
- Department of Molecular Medicine, Aarhus University Hospital, Aarhus, Denmark
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The intricate relationship between RNA structure, editing, and splicing. Semin Cell Dev Biol 2011; 23:281-8. [PMID: 22178616 DOI: 10.1016/j.semcdb.2011.11.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Revised: 11/15/2011] [Accepted: 11/17/2011] [Indexed: 11/23/2022]
Abstract
Post-transcriptional modifications such as RNA editing and splicing diversify the proteome while limiting the necessary size of the genome. Although splicing globally rearranges existing information within the transcript, the conserved process of adenosine-to-inosine RNA editing recodes the message through single nucleotide changes, often at very specific locations. Because inosine is interpreted as guanosine by the cellular machineries, editing effectively results in the substitution of a guanosine for an adenosine in the primary RNA sequence. Precise control of editing is dictated by duplex structures in the transcript, formed between the exonic region surrounding the editing site and cis regulatory elements often localized in a nearby intron, suggesting that editing must precede splicing. However, the precise relationship between these post-transcriptional processes remains unclear. Here we present general commonalities of RNA editing substrates and consequential predictions regarding the interaction between editing and splicing. We also discuss anomalies and interesting cases of RNA editing that confound our understanding of the relationship between these post-transcriptional processes.
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Orlandi C, Barbon A, Barlati S. Activity Regulation of Adenosine Deaminases Acting on RNA (ADARs). Mol Neurobiol 2011; 45:61-75. [DOI: 10.1007/s12035-011-8220-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Accepted: 11/09/2011] [Indexed: 01/01/2023]
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Gommans WM. A-to-I editing of microRNAs: regulating the regulators? Semin Cell Dev Biol 2011; 23:251-7. [PMID: 22001383 DOI: 10.1016/j.semcdb.2011.09.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 09/19/2011] [Accepted: 09/28/2011] [Indexed: 01/10/2023]
Abstract
An important epigenetic mechanism in mammals is adenosine deamination, which generates transcriptome variety through the conversion of single adenosines into inosines in RNA molecules. Inosine is interpreted as guanosine by the translational machinery, and when A-to-I RNA editing occurs in the coding region of pre-mRNA molecules this substitution can result in non-synonymous codon changes and subsequent altered protein function. Furthermore, editing can also take place in non-coding RNA molecules, including pri-miRNAs. In this review I intend to give an overview on the interplay between miRNA-mediated control of gene expression and RNA editing, and how editing could impact cellular behavior by influencing mature miRNA expression levels.
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Gallo A, Locatelli F. ADARs: allies or enemies? The importance of A-to-I RNA editing in human disease: from cancer to HIV-1. Biol Rev Camb Philos Soc 2011; 87:95-110. [PMID: 21682836 DOI: 10.1111/j.1469-185x.2011.00186.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Adenosine deaminases acting on RNA (ADARs) are enzymes that convert adenosine (A) to inosine (I) in nuclear-encoded RNAs and viral RNAs. The activity of ADARs has been demonstrated to be essential in mammals and serves to fine-tune different proteins and modulate many molecular pathways. Recent findings have shown that ADAR activity is altered in many pathological tissues. Moreover, it has been shown that modulation of RNA editing is important for cell proliferation and migration, and has a protective effect on ischaemic insults. This review summarises available recent knowledge on A-to-I RNA editing and ADAR enzymes, with particular attention given to the emerging role played by these enzymes in cancer, some infectious diseases and immune-mediated disorders.
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Affiliation(s)
- Angela Gallo
- RNA Editing Laboratory, Oncohaematology Department, IRCCS, Ospedale Pediatrico "Bambino Gesù", Rome, Italy.
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Zamyatnin AA, Lyamzaev KG, Zinovkin RA. A-to-I RNA editing: a contribution to diversity of the transcriptome and an organism's development. BIOCHEMISTRY (MOSCOW) 2011; 75:1316-23. [PMID: 21314598 DOI: 10.1134/s0006297910110027] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The complexity of multicellular organisms requires both an increase in genetic information and fine tuning in regulation of gene expression. One of the mechanisms responsible for these functions is RNA editing. RNA editing is a complex process affecting the mechanism of changes in transcriptome sequences. The best studied example of this process is A-to-I RNA editing. On the organism's level, RNA editing plays a key role during ontogenesis and in the defense against pathogens. Disorders in A-to-I RNA editing lead to serious abnormalities. The importance of RNA editing increases with an increase in the organism's complexity. Correct RNA editing is an indispensable factor of an organism's development and probably determines the lifespan of higher eukaryotes.
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Affiliation(s)
- A A Zamyatnin
- Institute of Mitoengineering and Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russia.
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Mattick JS. The central role of RNA in human development and cognition. FEBS Lett 2011; 585:1600-16. [DOI: 10.1016/j.febslet.2011.05.001] [Citation(s) in RCA: 149] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 05/03/2011] [Indexed: 12/22/2022]
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48
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Samuel CE. Adenosine deaminases acting on RNA (ADARs) are both antiviral and proviral. Virology 2011; 411:180-93. [PMID: 21211811 DOI: 10.1016/j.virol.2010.12.004] [Citation(s) in RCA: 240] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Accepted: 12/04/2010] [Indexed: 12/18/2022]
Abstract
A-to-I RNA editing, the deamination of adenosine (A) to inosine (I) that occurs in regions of RNA with double-stranded character, is catalyzed by a family of Adenosine Deaminases Acting on RNA (ADARs). In mammals there are three ADAR genes. Two encode proteins that possess demonstrated deaminase activity: ADAR1, which is interferon-inducible, and ADAR2 which is constitutively expressed. ADAR3, by contrast, has not yet been shown to be an active enzyme. The specificity of the ADAR1 and ADAR2 deaminases ranges from highly site-selective to non-selective, dependent on the duplex structure of the substrate RNA. A-to-I editing is a form of nucleotide substitution editing, because I is decoded as guanosine (G) instead of A by ribosomes during translation and by polymerases during RNA-dependent RNA replication. Additionally, A-to-I editing can alter RNA structure stability as I:U mismatches are less stable than A:U base pairs. Both viral and cellular RNAs are edited by ADARs. A-to-I editing is of broad physiologic significance. Among the outcomes of A-to-I editing are biochemical changes that affect how viruses interact with their hosts, changes that can lead to either enhanced or reduced virus growth and persistence depending upon the specific virus.
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Affiliation(s)
- Charles E Samuel
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106, USA.
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Abstract
One type of RNA editing converts adenosines to inosines (A-->I editing) in double-stranded RNA (dsRNA) substrates. A-->I RNA editing is mediated by adenosine deaminase acting on RNA (ADAR) enzymes. A-->I RNA editing of protein-coding sequences of a limited number of mammalian genes results in recoding and subsequent alterations of their functions. However, A-->I RNA editing most frequently targets repetitive RNA sequences located within introns and 5' and 3' untranslated regions (UTRs). Although the biological significance of noncoding RNA editing remains largely unknown, several possibilities, including its role in the control of endogenous short interfering RNAs (esiRNAs), have been proposed. Furthermore, recent studies have revealed that the biogenesis and functions of certain microRNAs (miRNAs) are regulated by the editing of their precursors. Here, I review the recent findings that indicate new functions for A-->I editing in the regulation of noncoding RNAs and for interactions between RNA editing and RNA interference mechanisms.
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Affiliation(s)
- Kazuko Nishikura
- Department of Gene Expression and Regulation, The Wistar Institute, Philadelphia, Pennsylvania 19104-4268, USA.
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Farajollahi S, Maas S. Molecular diversity through RNA editing: a balancing act. Trends Genet 2010; 26:221-30. [PMID: 20395010 PMCID: PMC2865426 DOI: 10.1016/j.tig.2010.02.001] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Revised: 02/11/2010] [Accepted: 02/12/2010] [Indexed: 01/26/2023]
Abstract
RNA editing by adenosine deamination fuels the generation of RNA and protein diversity in eukaryotes, particularly in higher organisms. This includes the recoding of translated exons, widespread editing of retrotransposon-derived repeat elements and sequence modification of microRNA (miRNA) transcripts. Such changes can bring about specific amino acid substitutions, alternative splicing and changes in gene expression levels. Although the overall prevalence of adenosine-to-inosine (A-to-I) editing and its specific functional impact on many of the affected genes is not yet known, the importance of balancing RNA modification levels across time and space is becoming increasingly evident. In particular, transcriptome instabilities in the form of too much or too little RNA editing activity, or misguided editing, manifest in several human disease phenotypes and can disrupt that balance.
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Affiliation(s)
- Sanaz Farajollahi
- Department of Biological Sciences, Lehigh University, Bethlehem, PA 18015, USA
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