1
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Deng Y, Zhou J, Li HB. The physiological and pathological roles of RNA modifications in T cells. Cell Chem Biol 2024:S2451-9456(24)00222-8. [PMID: 38986618 DOI: 10.1016/j.chembiol.2024.06.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Revised: 04/20/2024] [Accepted: 06/12/2024] [Indexed: 07/12/2024]
Abstract
RNA molecules undergo dynamic chemical modifications in response to various external or cellular stimuli. Some of those modifications have been demonstrated to post-transcriptionally modulate the RNA transcription, localization, stability, translation, and degradation, ultimately tuning the fate decisions and function of mammalian cells, particularly T cells. As a crucial part of adaptive immunity, T cells play fundamental roles in defending against infections and tumor cells. Recent findings have illuminated the importance of RNA modifications in modulating T cell survival, proliferation, differentiation, and functional activities. Therefore, understanding the epi-transcriptomic control of T cell biology enables a potential avenue for manipulating T cell immunity. This review aims to elucidate the physiological and pathological roles of internal RNA modifications in T cell development, differentiation, and functionality drawn from current literature, with the goal of inspiring new insights for future investigations and providing novel prospects for T cell-based immunotherapy.
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Affiliation(s)
- Yu Deng
- Shanghai Institute of Immunology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China; Shanghai Jiao Tong University School of Medicine-Yale Institute for Immune Metabolism, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Jing Zhou
- Shanghai Institute of Immunology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China; Shanghai Jiao Tong University School of Medicine-Yale Institute for Immune Metabolism, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Hua-Bing Li
- Shanghai Institute of Immunology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China; Shanghai Jiao Tong University School of Medicine-Yale Institute for Immune Metabolism, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China; Department of Geriatrics, Medical Center on Aging of Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China; Chongqing International Institute for Immunology, Chongqing 401320, China.
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2
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Szabo B, Mandl TC, Woldrich B, Diensthuber G, Martin D, Jantsch MF, Licht K. RNA Pol II-dependent transcription efficiency fine-tunes A-to-I editing levels. Genome Res 2024; 34:231-242. [PMID: 38471738 PMCID: PMC10984384 DOI: 10.1101/gr.277686.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Accepted: 02/15/2024] [Indexed: 03/14/2024]
Abstract
A-to-I RNA editing is a widespread epitranscriptomic phenomenon leading to the conversion of adenosines to inosines, which are primarily interpreted as guanosines by cellular machines. Consequently, A-to-I editing can alter splicing or lead to recoding of transcripts. As misregulation of editing can cause a variety of human diseases, A-to-I editing requires tight regulation of the extent of deamination, particularly in protein-coding regions. The bulk of A-to-I editing occurs cotranscriptionally. Thus, we studied A-to-I editing regulation in the context of transcription and pre-mRNA processing. We show that stimulation of transcription impacts editing levels. Activation of the transcription factor MYC leads to an up-regulation of A-to-I editing, particularly in transcripts that are suppressed upon MYC activation. Moreover, low pre-mRNA synthesis rates and low pre-mRNA expression levels support high levels of editing. We also show that editing levels greatly differ between nascent pre-mRNA and mRNA in a cellular system, as well as in mouse tissues. Editing levels can increase or decrease from pre-mRNA to mRNA and can vary across editing targets and across tissues, showing that pre-mRNA processing is an important layer of editing regulation. Several lines of evidence suggest that the differences emerge during pre-mRNA splicing. Moreover, actinomycin D treatment of primary neuronal cells and editing level analysis suggests that regulation of editing levels also depends on transcription.
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Affiliation(s)
- Brigitta Szabo
- Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Therese C Mandl
- Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Bernhard Woldrich
- Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Gregor Diensthuber
- Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - David Martin
- Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Michael F Jantsch
- Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Konstantin Licht
- Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria
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3
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Shen S, Zhang LS. The regulation of antiviral innate immunity through non-m 6A RNA modifications. Front Immunol 2023; 14:1286820. [PMID: 37915585 PMCID: PMC10616867 DOI: 10.3389/fimmu.2023.1286820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 10/04/2023] [Indexed: 11/03/2023] Open
Abstract
The post-transcriptional RNA modifications impact the dynamic regulation of gene expression in diverse biological and physiological processes. Host RNA modifications play an indispensable role in regulating innate immune responses against virus infection in mammals. Meanwhile, the viral RNAs can be deposited with RNA modifications to interfere with the host immune responses. The N6-methyladenosine (m6A) has boosted the recent emergence of RNA epigenetics, due to its high abundance and a transcriptome-wide widespread distribution in mammalian cells, proven to impact antiviral innate immunity. However, the other types of RNA modifications are also involved in regulating antiviral responses, and the functional roles of these non-m6A RNA modifications have not been comprehensively summarized. In this Review, we conclude the regulatory roles of 2'-O-methylation (Nm), 5-methylcytidine (m5C), adenosine-inosine editing (A-to-I editing), pseudouridine (Ψ), N1-methyladenosine (m1A), N7-methylguanosine (m7G), N6,2'-O-dimethyladenosine (m6Am), and N4-acetylcytidine (ac4C) in antiviral innate immunity. We provide a systematic introduction to the biogenesis and functions of these non-m6A RNA modifications in viral RNA, host RNA, and during virus-host interactions, emphasizing the biological functions of RNA modification regulators in antiviral responses. Furthermore, we discussed the recent research progress in the development of antiviral drugs through non-m6A RNA modifications. Collectively, this Review conveys knowledge and inspiration to researchers in multiple disciplines, highlighting the challenges and future directions in RNA epitranscriptome, immunology, and virology.
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Affiliation(s)
- Shenghai Shen
- Division of Life Science, The Hong Kong University of Science and Technology (HKUST), Kowloon, Hong Kong SAR, China
| | - Li-Sheng Zhang
- Division of Life Science, The Hong Kong University of Science and Technology (HKUST), Kowloon, Hong Kong SAR, China
- Department of Chemistry, The Hong Kong University of Science and Technology (HKUST), Kowloon, Hong Kong SAR, China
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4
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Sun H, Li K, Liu C, Yi C. Regulation and functions of non-m 6A mRNA modifications. Nat Rev Mol Cell Biol 2023; 24:714-731. [PMID: 37369853 DOI: 10.1038/s41580-023-00622-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/23/2023] [Indexed: 06/29/2023]
Abstract
Nucleobase modifications are prevalent in eukaryotic mRNA and their discovery has resulted in the emergence of epitranscriptomics as a research field. The most abundant internal (non-cap) mRNA modification is N6-methyladenosine (m6A), the study of which has revolutionized our understanding of post-transcriptional gene regulation. In addition, numerous other mRNA modifications are gaining great attention because of their major roles in RNA metabolism, immunity, development and disease. In this Review, we focus on the regulation and function of non-m6A modifications in eukaryotic mRNA, including pseudouridine (Ψ), N6,2'-O-dimethyladenosine (m6Am), N1-methyladenosine (m1A), inosine, 5-methylcytidine (m5C), N4-acetylcytidine (ac4C), 2'-O-methylated nucleotide (Nm) and internal N7-methylguanosine (m7G). We highlight their regulation, distribution, stoichiometry and known roles in mRNA metabolism, such as mRNA stability, translation, splicing and export. We also discuss their biological consequences in physiological and pathological processes. In addition, we cover research techniques to further study the non-m6A mRNA modifications and discuss their potential future applications.
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Affiliation(s)
- Hanxiao Sun
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Kai Li
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Cong Liu
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Chengqi Yi
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China.
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China.
- Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing, China.
- Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing, China.
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5
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Lim WF, Rinaldi C. RNA Transcript Diversity in Neuromuscular Research. J Neuromuscul Dis 2023:JND221601. [PMID: 37182892 DOI: 10.3233/jnd-221601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Three decades since the Human Genome Project began, scientists have now identified more then 25,000 protein coding genes in the human genome. The vast majority of the protein coding genes (> 90%) are multi-exonic, with the coding DNA being interrupted by intronic sequences, which are removed from the pre-mRNA transcripts before being translated into proteins, a process called splicing maturation. Variations in this process, i.e. by exon skipping, intron retention, alternative 5' splice site (5'ss), 3' splice site (3'ss), or polyadenylation usage, lead to remarkable transcriptome and proteome diversity in human tissues. Given its critical biological importance, alternative splicing is tightly regulated in a tissue- and developmental stage-specific manner. The central nervous system and skeletal muscle are amongst the tissues with the highest number of differentially expressed alternative exons, revealing a remarkable degree of transcriptome complexity. It is therefore not surprising that splicing mis-regulation is causally associated with a myriad of neuromuscular diseases, including but not limited to amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA), Duchenne muscular dystrophy (DMD), and myotonic dystrophy type 1 and 2 (DM1, DM2). A gene's transcript diversity has since become an integral and an important consideration for drug design, development and therapy. In this review, we will discuss transcript diversity in the context of neuromuscular diseases and current approaches to address splicing mis-regulation.
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Affiliation(s)
- Wooi Fang Lim
- Department of Paediatrics and Institute of Developmental and Regenerative Medicine, University of Oxford, Oxford, UK
| | - Carlo Rinaldi
- Department of Paediatrics and Institute of Developmental and Regenerative Medicine, University of Oxford, Oxford, UK
- MDUK Oxford Neuromuscular Centre, University of Oxford, Oxford, UK
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6
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Tassinari V, La Rosa P, Guida E, Colopi A, Caratelli S, De Paolis F, Gallo A, Cenciarelli C, Sconocchia G, Dolci S, Cesarini V. Contribution of A-to-I RNA editing, M6A RNA Methylation, and Alternative Splicing to physiological brain aging and neurodegenerative diseases. Mech Ageing Dev 2023; 212:111807. [PMID: 37023929 DOI: 10.1016/j.mad.2023.111807] [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] [Received: 02/14/2023] [Revised: 03/31/2023] [Accepted: 04/03/2023] [Indexed: 04/08/2023]
Abstract
Aging is a physiological and progressive phenomenon in all organisms' life cycle, characterized by the accumulation of degenerative processes triggered by several alterations within molecular pathways. These changes compromise cell fate, resulting in the loss of functions in tissues throughout the body, including the brain. Physiological brain aging has been linked to structural and functional alterations, as well as to an increased risk of neurodegenerative diseases. Post-transcriptional RNA modifications modulate mRNA coding properties, stability, translatability, expanding the coding capacity of the genome, and are involved in all cellular processes. Among mRNA post-transcriptional modifications, the A-to-I RNA editing, m6A RNA Methylation and Alternative Splicing play a critical role in all the phases of a neuronal cell life cycle and alterations in their mechanisms of action significantly contribute to aging and neurodegeneration. Here we review our current understanding of the contribution of A-to-I RNA editing, m6A RNA Methylation, and Alternative Splicing to physiological brain aging process and neurodegenerative diseases.
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Affiliation(s)
- Valentina Tassinari
- Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy; Department of Experimental Medicine, University of Rome Tor Vergata, Rome, Italy.
| | - Piergiorgio La Rosa
- Division of Neuroscience, Department of Psychology, Sapienza University of Rome, Rome, Italy; European Center for Brain Research, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Eugenia Guida
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy
| | - Ambra Colopi
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy
| | - Sara Caratelli
- Department of Biomedicine, Institute of Translational Pharmacology (IFT), National Research Council (CNR), Rome, Italy
| | - Francesca De Paolis
- Department of Biomedicine, Institute of Translational Pharmacology (IFT), National Research Council (CNR), Rome, Italy
| | - Angela Gallo
- RNA Editing Lab., Oncohaematology Department, Cellular and Gene Therapy Unit, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Carlo Cenciarelli
- Department of Biomedicine, Institute of Translational Pharmacology (IFT), National Research Council (CNR), Rome, Italy
| | - Giuseppe Sconocchia
- Department of Biomedicine, Institute of Translational Pharmacology (IFT), National Research Council (CNR), Rome, Italy
| | - Susanna Dolci
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy
| | - Valeriana Cesarini
- Department of Biomedicine, Institute of Translational Pharmacology (IFT), National Research Council (CNR), Rome, Italy.
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7
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Fu T, Chan TW, Bahn JH, Kim TH, Rowat AC, Xiao X. Multifaceted role of RNA editing in promoting loss-of-function of PODXL in cancer. iScience 2022; 25:104836. [PMID: 35992085 PMCID: PMC9382340 DOI: 10.1016/j.isci.2022.104836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 06/16/2022] [Accepted: 07/20/2022] [Indexed: 12/03/2022] Open
Abstract
PODXL, a protein that is dysregulated in multiple cancers, plays an important role in promoting cancer metastasis. In this study, we report that RNA editing promotes the inclusion of a PODXL alternative exon. The resulting edited PODXL long isoform is more prone to protease digestion and has the strongest effects on reducing cell migration and cisplatin chemoresistance among the three PODXL isoforms (short, unedited long, and edited long isoforms). Importantly, the editing level of the PODXL recoding site and the inclusion level of the PODXL alternative exon are strongly associated with overall patient survival in Kidney Renal Clear Cell Carcinoma (KIRC). Supported by significant enrichment of exonic RNA editing sites in alternatively spliced exons, we hypothesize that exonic RNA editing sites may enhance proteomic diversity through alternative splicing, in addition to amino acid changes, a previously under-appreciated aspect of RNA editing function.
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Affiliation(s)
- Ting Fu
- Molecular, Cellular, and Integrative Physiology Interdepartmental Program, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Tracey W. Chan
- Bioinformatics Interdepartmental Program, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Jae Hoon Bahn
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Tae-Hyung Kim
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Amy C. Rowat
- Molecular, Cellular, and Integrative Physiology Interdepartmental Program, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Xinshu Xiao
- Molecular, Cellular, and Integrative Physiology Interdepartmental Program, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Bioinformatics Interdepartmental Program, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA 90095, USA
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8
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Zhai J, Koh JH, Soong TW. RNA editing of ion channels and receptors in physiology and neurological disorders. OXFORD OPEN NEUROSCIENCE 2022; 1:kvac010. [PMID: 38596706 PMCID: PMC11003377 DOI: 10.1093/oons/kvac010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 04/14/2022] [Accepted: 05/15/2022] [Indexed: 04/11/2024]
Abstract
Adenosine-to-inosine (A-to-I) RNA editing is a post-transcriptional modification that diversifies protein functions by recoding RNA or alters protein quantity by regulating mRNA level. A-to-I editing is catalyzed by adenosine deaminases that act on RNA. Millions of editing sites have been reported, but they are mostly found in non-coding sequences. However, there are also several recoding editing sites in transcripts coding for ion channels or transporters that have been shown to play important roles in physiology and changes in editing level are associated with neurological diseases. These editing sites are not only found to be evolutionary conserved across species, but they are also dynamically regulated spatially, developmentally and by environmental factors. In this review, we discuss the current knowledge of A-to-I RNA editing of ion channels and receptors in the context of their roles in physiology and pathological disease. We also discuss the regulation of editing events and site-directed RNA editing approaches for functional study that offer a therapeutic pathway for clinical applications.
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Affiliation(s)
- Jing Zhai
- Department of Physiology, National University of Singapore, Singapore 117593, Singapore
| | - Joanne Huifen Koh
- Department of Physiology, National University of Singapore, Singapore 117593, Singapore
| | - Tuck Wah Soong
- Department of Physiology, National University of Singapore, Singapore 117593, Singapore
- Healthy Longevity Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore,
Singapore 117456, Singapore
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9
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Katrekar D, Yen J, Xiang Y, Saha A, Meluzzi D, Savva Y, Mali P. Efficient in vitro and in vivo RNA editing via recruitment of endogenous ADARs using circular guide RNAs. Nat Biotechnol 2022; 40:938-945. [PMID: 35145312 PMCID: PMC9232839 DOI: 10.1038/s41587-021-01171-4] [Citation(s) in RCA: 67] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 11/24/2021] [Indexed: 12/14/2022]
Abstract
Recruiting endogenous adenosine deaminases using exogenous guide RNAs to edit cellular RNAs is a promising therapeutic strategy, but editing efficiency and durability remain low using current guide RNA designs. In this study, we engineered circular ADAR-recruiting guide RNAs (cadRNAs) to enable more efficient programmable adenosine-to-inosine RNA editing without requiring co-delivery of any exogenous proteins. Using these cadRNAs, we observed robust and durable RNA editing across multiple sites and cell lines, in both untranslated and coding regions of RNAs, and high transcriptome-wide specificity. Additionally, we increased transcript-level specificity for the target adenosine by incorporating interspersed loops in the antisense domains, reducing bystander editing. In vivo delivery of cadRNAs via adeno-associated viruses enabled 53% RNA editing of the mPCSK9 transcript in C57BL/6J mice livers and 12% UAG-to-UGG RNA correction of the amber nonsense mutation in the IDUA-W392X mouse model of mucopolysaccharidosis type I-Hurler syndrome. cadRNAs enable efficient programmable RNA editing in vivo with diverse protein modulation and gene therapeutic applications.
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Affiliation(s)
- Dhruva Katrekar
- Department of Bioengineering, University of California, San Diego, San Diego, CA, USA
| | - James Yen
- Department of Bioengineering, University of California, San Diego, San Diego, CA, USA
| | - Yichen Xiang
- Department of Bioengineering, University of California, San Diego, San Diego, CA, USA
| | - Anushka Saha
- Department of Bioengineering, University of California, San Diego, San Diego, CA, USA
| | - Dario Meluzzi
- Department of Medicine, University of California, San Diego, San Diego, CA, USA
| | | | - Prashant Mali
- Department of Bioengineering, University of California, San Diego, San Diego, CA, USA.
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10
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Li C, Shi X, Yang J, Li K, Dai L, Zhang Y, Zhou M, Su J. Genome-wide characterization of RNA editing highlights roles of high editing events of glutamatergic synapse during mouse retinal development. Comput Struct Biotechnol J 2022; 20:2648-2656. [PMID: 35685368 PMCID: PMC9162912 DOI: 10.1016/j.csbj.2022.05.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 05/14/2022] [Accepted: 05/14/2022] [Indexed: 11/30/2022] Open
Abstract
Adenosine-to-inosine (A-to-I) RNA editing leads to functional change of neurotransmitter receptor which is essential for neurotransmission and normal neuronal development. As a highly accessible part of central nervous system, retina has been extensively studied, however, it remains largely unknown how RNA editing regulates its development. Here, a genome-wide screening of high-confidence RNA editing events were performed to decipher the dynamic transcriptome regulation by RNA editing during mouse retinal development. 2000 high-confidence editing sites across eight developmental stages of retina were called. Three unique patterns (RNA-editinghigh pattern, RNA-editingmedium pattern and RNA-editinglow pattern) were identified by clustering these editing sites based on their editing level during retinal development. Editing events from RNA-editinghigh pattern were significantly associated with glutamate receptors and regulated synaptic transmission. Interestingly, most non-synonymous high-editing sites were mapped to ion channel genes of glutamatergic synapse which were associated with neurotransmission by controlling ion channel permeability and affecting exocytosis. Meanwhile, these non-synonymous editing sites were evolutionarily conserved and exhibited a consistently increasing editing levels between mouse and human retinal development. Single-cell RNA-seq data analysis revealed that RNA editing events prefer to occur in two main cell types including bipolar and amacrine cells. Genes with non-synonymous high-editing sites were enriched in both bipolar cells and retina ganglion cells, which may mediate retina ganglion cell differentiation by altering channel ion permeability. Together, our results provide novel insights into mechanism of post-transcriptional regulation during retinal development and help to develop novel RNA editing-guided therapeutic strategies for retinal disorders.
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Affiliation(s)
- Chenghao Li
- School of Biomedical Engineering, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang 325027, China
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Wenzhou, Zhejiang 325001, China
| | - Xinrui Shi
- School of Biomedical Engineering, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang 325027, China
| | - Jiaying Yang
- School of Biomedical Engineering, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang 325027, China
| | - Ke Li
- School of Biomedical Engineering, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang 325027, China
| | - Lijun Dai
- School of Biomedical Engineering, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang 325027, China
| | - Yan Zhang
- School of Biomedical Engineering, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang 325027, China
| | - Meng Zhou
- School of Biomedical Engineering, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang 325027, China
- Corresponding authorsat: School of Biomedical Engineering, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang 325027, China (J. Su).
| | - Jianzhong Su
- School of Biomedical Engineering, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang 325027, China
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Wenzhou, Zhejiang 325001, China
- Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang 325011, China
- Corresponding authorsat: School of Biomedical Engineering, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang 325027, China (J. Su).
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11
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Dutta N, Deb I, Sarzynska J, Lahiri A. Inosine and its methyl derivatives: Occurrence, biogenesis, and function in RNA. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2022; 169-170:21-52. [PMID: 35065168 DOI: 10.1016/j.pbiomolbio.2022.01.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 12/11/2021] [Accepted: 01/11/2022] [Indexed: 05/21/2023]
Abstract
Inosine is one of the most common post-transcriptional modifications. Since its discovery, it has been noted for its ability to contribute to non-Watson-Crick interactions within RNA. Rapidly accumulating evidence points to the widespread generation of inosine through hydrolytic deamination of adenosine to inosine by different classes of adenosine deaminases. Three naturally occurring methyl derivatives of inosine, i.e., 1-methylinosine, 2'-O-methylinosine and 1,2'-O-dimethylinosine are currently reported in RNA modification databases. These modifications are expected to lead to changes in the structure, folding, dynamics, stability and functions of RNA. The importance of the modifications is indicated by the strong conservation of the modifying enzymes across organisms. The structure, binding and catalytic mechanism of the adenosine deaminases have been well-studied, but the underlying mechanism of the catalytic reaction is not very clear yet. Here we extensively review the existing data on the occurrence, biogenesis and functions of inosine and its methyl derivatives in RNA. We also included the structural and thermodynamic aspects of these modifications in our review to provide a detailed and integrated discussion on the consequences of A-to-I editing in RNA and the contribution of different structural and thermodynamic studies in understanding its role in RNA. We also highlight the importance of further studies for a better understanding of the mechanisms of the different classes of deamination reactions. Further investigation of the structural and thermodynamic consequences and functions of these modifications in RNA should provide more useful information about their role in different diseases.
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Affiliation(s)
- Nivedita Dutta
- Department of Biophysics, Molecular Biology and Bioinformatics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata, 700009, West Bengal, India
| | - Indrajit Deb
- Department of Biophysics, Molecular Biology and Bioinformatics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata, 700009, West Bengal, India
| | - Joanna Sarzynska
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznan, Poland
| | - Ansuman Lahiri
- Department of Biophysics, Molecular Biology and Bioinformatics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata, 700009, West Bengal, India.
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12
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Katrekar D, Xiang Y, Palmer N, Saha A, Meluzzi D, Mali P. Comprehensive interrogation of the ADAR2 deaminase domain for engineering enhanced RNA editing activity and specificity. eLife 2022; 11:75555. [PMID: 35044296 PMCID: PMC8809894 DOI: 10.7554/elife.75555] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Accepted: 01/18/2022] [Indexed: 11/17/2022] Open
Abstract
Adenosine deaminases acting on RNA (ADARs) can be repurposed to enable programmable RNA editing, however their exogenous delivery leads to transcriptome-wide off-targeting, and additionally, enzymatic activity on certain RNA motifs, especially those flanked by a 5’ guanosine is very low thus limiting their utility as a transcriptome engineering toolset. Towards addressing these issues, we first performed a novel deep mutational scan of the ADAR2 deaminase domain, directly measuring the impact of every amino acid substitution across 261 residues, on RNA editing. This enabled us to create a domain-wide mutagenesis map while also revealing a novel hyperactive variant with improved enzymatic activity at 5’-GAN-3’ motifs. As overexpression of ADAR enzymes, especially hyperactive variants, can lead to significant transcriptome-wide off-targeting, we next engineered a split-ADAR2 deaminase which resulted in >100-fold more specific RNA editing as compared to full-length deaminase overexpression. Taken together, we anticipate this systematic engineering of the ADAR2 deaminase domain will enable broader utility of the ADAR toolset for RNA biotechnology applications.
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Affiliation(s)
| | - Yichen Xiang
- Department of Bioengineering, University of California, San Diego
| | - Nathan Palmer
- Division of Biological Sciences, University of California, San Diego
| | - Anushka Saha
- Department of Bioengineering, University of California, San Diego
| | - Dario Meluzzi
- Department of Bioengineering, University of California, San Diego
| | - Prashant Mali
- Department of Bioengineering, University of California, San Diego
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13
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Tang T, Han Y, Wang Y, Huang H, Qian P. Programmable System of Cas13-Mediated RNA Modification and Its Biological and Biomedical Applications. Front Cell Dev Biol 2021; 9:677587. [PMID: 34386490 PMCID: PMC8353156 DOI: 10.3389/fcell.2021.677587] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 06/16/2021] [Indexed: 12/15/2022] Open
Abstract
Clustered regularly interspaced short palindromic repeats (CRISPR)-Cas13 has drawn broad interest to control gene expression and cell fate at the RNA level in general. Apart from RNA interference mediated by its endonuclease activity, the nuclease-deactivated form of Cas13 further provides a versatile RNA-guided RNA-targeting platform for manipulating kinds of RNA modifications post-transcriptionally. Chemical modifications modulate various aspects of RNA fate, including translation efficiency, alternative splicing, RNA–protein affinity, RNA–RNA interaction, RNA stability and RNA translocation, which ultimately orchestrate cellular biologic activities. This review summarizes the history of the CRISPR-Cas13 system, fundamental components of RNA modifications and the related physiological and pathological functions. We focus on the development of epi-transcriptional editing toolkits based on catalytically inactive Cas13, including RNA Editing for Programmable A to I Replacement (REPAIR) and xABE (adenosine base editor) for adenosine deamination, RNA Editing for Specific C-to-U Exchange (RESCUE) and xCBE (cytidine base editor) for cytidine deamination and dm6ACRISPR, as well as the targeted RNA methylation (TRM) and photoactivatable RNA m6A editing system using CRISPR-dCas13 (PAMEC) for m6A editing. We further highlight the emerging applications of these useful toolkits in cell biology, disease and imaging. Finally, we discuss the potential limitations, such as off-target editing, low editing efficiency and limitation for AAV delivery, and provide possible optimization strategies.
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Affiliation(s)
- Tian Tang
- Center of Stem Cell and Regenerative Medicine, and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Institute of Hematology, Zhejiang University & Zhejiang Engineering Laboratory for Stem Cell and Immunotherapy, Hangzhou, China.,Zhejiang Laboratory for Systems & Precision Medicine, Zhejiang University Medical Center, Hangzhou, China.,Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine, Zhejiang University, Hangzhou, China
| | - Yingli Han
- Center of Stem Cell and Regenerative Medicine, and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Institute of Hematology, Zhejiang University & Zhejiang Engineering Laboratory for Stem Cell and Immunotherapy, Hangzhou, China.,Zhejiang Laboratory for Systems & Precision Medicine, Zhejiang University Medical Center, Hangzhou, China.,Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine, Zhejiang University, Hangzhou, China
| | - Yuran Wang
- Center of Stem Cell and Regenerative Medicine, and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Institute of Hematology, Zhejiang University & Zhejiang Engineering Laboratory for Stem Cell and Immunotherapy, Hangzhou, China.,Zhejiang Laboratory for Systems & Precision Medicine, Zhejiang University Medical Center, Hangzhou, China.,Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine, Zhejiang University, Hangzhou, China
| | - He Huang
- Center of Stem Cell and Regenerative Medicine, and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Institute of Hematology, Zhejiang University & Zhejiang Engineering Laboratory for Stem Cell and Immunotherapy, Hangzhou, China.,Zhejiang Laboratory for Systems & Precision Medicine, Zhejiang University Medical Center, Hangzhou, China
| | - Pengxu Qian
- Center of Stem Cell and Regenerative Medicine, and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Institute of Hematology, Zhejiang University & Zhejiang Engineering Laboratory for Stem Cell and Immunotherapy, Hangzhou, China.,Zhejiang Laboratory for Systems & Precision Medicine, Zhejiang University Medical Center, Hangzhou, China.,Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine, Zhejiang University, Hangzhou, China
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14
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Herbrechter R, Hube N, Buchholz R, Reiner A. Splicing and editing of ionotropic glutamate receptors: a comprehensive analysis based on human RNA-Seq data. Cell Mol Life Sci 2021; 78:5605-5630. [PMID: 34100982 PMCID: PMC8257547 DOI: 10.1007/s00018-021-03865-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Revised: 05/12/2021] [Accepted: 05/22/2021] [Indexed: 12/11/2022]
Abstract
Ionotropic glutamate receptors (iGluRs) play key roles for signaling in the central nervous system. Alternative splicing and RNA editing are well-known mechanisms to increase iGluR diversity and to provide context-dependent regulation. Earlier work on isoform identification has focused on the analysis of cloned transcripts, mostly from rodents. We here set out to obtain a systematic overview of iGluR splicing and editing in human brain based on RNA-Seq data. Using data from two large-scale transcriptome studies, we established a workflow for the de novo identification and quantification of alternative splice and editing events. We detected all canonical iGluR splice junctions, assessed the abundance of alternative events described in the literature, and identified new splice events in AMPA, kainate, delta, and NMDA receptor subunits. Notable events include an abundant transcript encoding the GluA4 amino-terminal domain, GluA4-ATD, a novel C-terminal GluD1 (delta receptor 1) isoform, GluD1-b, and potentially new GluK4 and GluN2C isoforms. C-terminal GluN1 splicing may be controlled by inclusion of a cassette exon, which shows preference for one of the two acceptor sites in the last exon. Moreover, we identified alternative untranslated regions (UTRs) and species-specific differences in splicing. In contrast, editing in exonic iGluR regions appears to be mostly limited to ten previously described sites, two of which result in silent amino acid changes. Coupling of proximal editing/editing and editing/splice events occurs to variable degree. Overall, this analysis provides the first inventory of alternative splicing and editing in human brain iGluRs and provides the impetus for further transcriptome-based and functional investigations.
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Affiliation(s)
- Robin Herbrechter
- Department of Biology and Biotechnology, Ruhr University Bochum, Universitätsstrasse 150, 44801, Bochum, Germany
| | - Nadine Hube
- Department of Biology and Biotechnology, Ruhr University Bochum, Universitätsstrasse 150, 44801, Bochum, Germany
| | - Raoul Buchholz
- Department of Biology and Biotechnology, Ruhr University Bochum, Universitätsstrasse 150, 44801, Bochum, Germany
| | - Andreas Reiner
- Department of Biology and Biotechnology, Ruhr University Bochum, Universitätsstrasse 150, 44801, Bochum, Germany.
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15
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Yang Y, Okada S, Sakurai M. Adenosine-to-inosine RNA editing in neurological development and disease. RNA Biol 2021; 18:999-1013. [PMID: 33393416 DOI: 10.1080/15476286.2020.1867797] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Adenosine-to-inosine (A-to-I) editing is one of the most prevalent post-transcriptional RNA modifications in metazoan. This reaction is catalysed by enzymes called adenosine deaminases acting on RNA (ADARs). RNA editing is involved in the regulation of protein function and gene expression. The numerous A-to-I editing sites have been identified in both coding and non-coding RNA transcripts. These editing sites are also found in various genes expressed in the central nervous system (CNS) and play an important role in neurological development and brain function. Aberrant regulation of RNA editing has been associated with the pathogenesis of neurological and psychiatric disorders, suggesting the physiological significance of RNA editing in the CNS. In this review, we discuss the current knowledge of editing on neurological disease and development.
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Affiliation(s)
- Yuxi Yang
- Research Institute for Biomedical Sciences, Tokyo University of Science, Noda-shi, Chiba, Japan
| | - Shunpei Okada
- Research Institute for Biomedical Sciences, Tokyo University of Science, Noda-shi, Chiba, Japan
| | - Masayuki Sakurai
- Research Institute for Biomedical Sciences, Tokyo University of Science, Noda-shi, Chiba, Japan
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16
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Míková H, Kuchtiak V, Svobodová I, Spišská V, Pačesová D, Balík A, Bendová Z. Circadian Regulation of GluA2 mRNA Processing in the Rat Suprachiasmatic Nucleus and Other Brain Structures. Mol Neurobiol 2021; 58:439-449. [PMID: 32964314 DOI: 10.1007/s12035-020-02141-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 09/17/2020] [Indexed: 11/30/2022]
Abstract
The mammalian circadian system consists of a major circadian pacemaker located in the suprachiasmatic nucleus (SCN) of the hypothalamus and peripheral clocks in the body, including brain structures. The SCN depends on glutamatergic neurotransmission for transmitting signals from the retina, and it exhibits spontaneous 24-h rhythmicity in neural activity. The aim of this work was to evaluate the degree and circadian rhythmicity of AMPA receptor GluA2 subunit R/G editing and alternative flip/flop splicing in the SCN and other brain structures in Wistar rats. Our data show that the circadian rhythmicity in the SCN's GluA2 mRNA level was highest at dawn, while the circadian rhythm in R/G editing peaked at CT10 and the rhythmic flip varied with the acrophase at the late subjective night. The circadian rhythmicity was confirmed for R/G editing and splicing in the CA3 hippocampal area, and rhythmic variation of the flip isoform was also measured in the olfactory bulbs and cerebellum. The correlations between the R/G editing and alternative flip/flop splicing revealed a structure-dependent direction. In the hippocampus, the edited (G)-form level was positively correlated with the flip variant abundance, in accord with published data; by contrast, in the SCN, the flip variant was in associated more with the unedited (R) form. The edited (G) form and flop isoform also predominated in the retina and cerebellum.
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Affiliation(s)
- Hana Míková
- Faculty of Science, Department of Physiology, Charles University, Viničná 7, 128 43, Prague 2, Czech Republic
| | - Viktor Kuchtiak
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Irena Svobodová
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Veronika Spišská
- Faculty of Science, Department of Physiology, Charles University, Viničná 7, 128 43, Prague 2, Czech Republic
| | - Dominika Pačesová
- Faculty of Science, Department of Physiology, Charles University, Viničná 7, 128 43, Prague 2, Czech Republic
- National Institute of Mental Health, Klecany, Czech Republic
| | - Aleš Balík
- Faculty of Science, Department of Physiology, Charles University, Viničná 7, 128 43, Prague 2, Czech Republic.
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
- Department of Cellular Neurophysiology, Institute of Physiology, Czech Academy of Sciences, BIOCEV, Prumyslova 595, 252 50, Vestec, Czech Republic.
| | - Zdeňka Bendová
- Faculty of Science, Department of Physiology, Charles University, Viničná 7, 128 43, Prague 2, Czech Republic.
- National Institute of Mental Health, Klecany, Czech Republic.
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17
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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: 23] [Impact Index Per Article: 5.8] [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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18
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Wu D, Zang YY, Shi YY, Ye C, Cai WM, Tang XH, Zhao L, Liu Y, Gan Z, Chen GQ, Xu Y, Yang JJ, Shi YS. Distant coupling between RNA editing and alternative splicing of the osmosensitive cation channel Tmem63b. J Biol Chem 2020; 295:18199-18212. [PMID: 33100268 PMCID: PMC7939439 DOI: 10.1074/jbc.ra120.016049] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/17/2020] [Indexed: 11/06/2022] Open
Abstract
Post-transcriptional modifications of pre-mRNAs expand the diversity of proteomes in higher eukaryotes. In the brain, these modifications diversify the functional output of many critical neuronal signal molecules. In this study, we identified a brain-specific A-to-I RNA editing that changed glutamine to arginine (Q/R) at exon 20 and an alternative splicing of exon 4 in Tmem63b, which encodes a ubiquitously expressed osmosensitive cation channel. The channel isoforms lacking exon 4 occurred in ∼80% of Tmem63b mRNAs in the brain but were not detected in other tissues, suggesting a brain-specific splicing. We found that the Q/R editing was catalyzed by Adar2 (Adarb1) and required an editing site complementary sequence located in the proximal 5' end of intron 20. Moreover, the Q/R editing was almost exclusively identified in the splicing isoform lacking exon 4, indicating a coupling between the editing and the splicing. Elimination of the Q/R editing in brain-specific Adar2 knockout mice did not affect the splicing efficiency of exon 4. Furthermore, transfection with the splicing isoform containing exon 4 suppressed the Q/R editing in primary cultured cerebellar granule neurons. Thus, our study revealed a coupling between an RNA editing and a distant alternative splicing in the Tmem63b pre-mRNA, in which the splicing plays a dominant role. Finally, physiological analysis showed that the splicing and the editing coordinately regulate Ca2+ permeability and osmosensitivity of channel proteins, which may contribute to their functions in the brain.
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Affiliation(s)
- Dan Wu
- Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Medical School, Nanjing University, Nanjing, China; State Key Laboratory of Pharmaceutical Biotechnology, Department of Neurology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing University, Nanjing, China
| | - Yan-Yu Zang
- Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Medical School, Nanjing University, Nanjing, China; State Key Laboratory of Pharmaceutical Biotechnology, Department of Neurology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing University, Nanjing, China
| | - Yong-Yun Shi
- Department of Orthopaedics, Luhe People's Hospital Affiliated to Yangzhou University, Nanjing, China
| | - Chang Ye
- Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Medical School, Nanjing University, Nanjing, China; State Key Laboratory of Pharmaceutical Biotechnology, Department of Neurology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing University, Nanjing, China
| | - Wen-Min Cai
- Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Medical School, Nanjing University, Nanjing, China; State Key Laboratory of Pharmaceutical Biotechnology, Department of Neurology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing University, Nanjing, China
| | - Xiao-Hui Tang
- Department of Anesthesiology and Perioperative Medicine, First Affiliated Hospital of Zhengzhou University, Zhengzhou, China; School of Medicine, Southeast University, Nanjing, China
| | - Liyun Zhao
- Translational Science and Clinical Biomarker, BeiGene (Shanghai) Co., Ltd., Shanghai, China
| | - Yong Liu
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Institute for Advanced Studies, Wuhan University, Wuhan, China
| | - Zhenji Gan
- Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Medical School, Nanjing University, Nanjing, China; State Key Laboratory of Pharmaceutical Biotechnology, Department of Neurology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing University, Nanjing, China
| | - Gui-Quan Chen
- Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Medical School, Nanjing University, Nanjing, China; State Key Laboratory of Pharmaceutical Biotechnology, Department of Neurology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing University, Nanjing, China; Institute for Brain Sciences, Nanjing University, Nanjing, China
| | - Yun Xu
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Neurology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing University, Nanjing, China; Institute for Brain Sciences, Nanjing University, Nanjing, China
| | - Jian-Jun Yang
- Department of Anesthesiology and Perioperative Medicine, First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.
| | - Yun Stone Shi
- Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Medical School, Nanjing University, Nanjing, China; State Key Laboratory of Pharmaceutical Biotechnology, Department of Neurology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing University, Nanjing, China; Institute for Brain Sciences, Nanjing University, Nanjing, China; Chemistry and Biomedicine Innovation Center, Nanjing University, Nanjing, China.
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19
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Cai W, Shi L, Cao M, Shen D, Li J, Zhang S, Song J. Pan-RNA editing analysis of the bovine genome. RNA Biol 2020; 18:368-381. [PMID: 32794424 DOI: 10.1080/15476286.2020.1807724] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
RNA editing is an essential process for modifying nucleotides at specific RNA sites during post-transcription in many species. However, its genomic landscape and characters have not been systematically explored in the bovine genome. In the present study, we characterized global RNA editing profiles from 50 samples of cattle and revealed a range of RNA editing profiles in different tissues. Most editing sites were significantly enriched in specific BovB-derived SINEs, especially the dispersed Bov-tAs, which likely forms dsRNA structures similar to the primate-specific Alu elements. Interestingly, ADARB1 (ADAR2) was observed to be predominant in determining global editing in the bovine genome. Common RNA editing sites among similar tissues were associated with tissue-specific biological functions. Taken together, the wide distribution of RNA editing sites and their tissue-specific characters implied the bovine RNA editome should be further explored.
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Affiliation(s)
- Wentao Cai
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China.,Department of Animal and Avian Science, University of Maryland, College Park, USA.,Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture & National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Lijun Shi
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Mingyue Cao
- Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture & National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Dan Shen
- Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture & National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Junya Li
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Shengli Zhang
- Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture & National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Jiuzhou Song
- Department of Animal and Avian Science, University of Maryland, College Park, USA
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20
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Kapoor U, Licht K, Amman F, Jakobi T, Martin D, Dieterich C, Jantsch MF. ADAR-deficiency perturbs the global splicing landscape in mouse tissues. Genome Res 2020; 30:1107-1118. [PMID: 32727871 PMCID: PMC7462079 DOI: 10.1101/gr.256933.119] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 07/10/2020] [Indexed: 02/06/2023]
Abstract
Adenosine-to-inosine RNA editing and pre-mRNA splicing largely occur cotranscriptionally and influence each other. Here, we use mice deficient in either one of the two editing enzymes ADAR (ADAR1) or ADARB1 (ADAR2) to determine the transcriptome-wide impact of RNA editing on splicing across different tissues. We find that ADAR has a 100× higher impact on splicing than ADARB1, although both enzymes target a similar number of substrates with a large common overlap. Consistently, differentially spliced regions frequently harbor ADAR editing sites. Moreover, catalytically dead ADAR also impacts splicing, demonstrating that RNA binding of ADAR affects splicing. In contrast, ADARB1 editing sites are found enriched 5′ of differentially spliced regions. Several of these ADARB1-mediated editing events change splice consensus sequences, therefore strongly influencing splicing of some mRNAs. A significant overlap between differentially edited and differentially spliced sites suggests evolutionary selection toward splicing being regulated by editing in a tissue-specific manner.
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Affiliation(s)
- Utkarsh Kapoor
- Center of Anatomy and Cell Biology, Department of Cell and Developmental Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Konstantin Licht
- Center of Anatomy and Cell Biology, Department of Cell and Developmental Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Fabian Amman
- Center of Anatomy and Cell Biology, Department of Cell and Developmental Biology, Medical University of Vienna, A-1090 Vienna, Austria.,Institute of Theoretical Biochemistry, University of Vienna, A-1090 Vienna, Austria
| | - Tobias Jakobi
- Department of Internal Medicine III and Klaus Tschira Institute for Computational Cardiology, Section of Bioinformatics and Systems Cardiology, University Hospital, D-96120 Heidelberg, Germany
| | - David Martin
- Center of Anatomy and Cell Biology, Department of Cell and Developmental Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Christoph Dieterich
- Department of Internal Medicine III and Klaus Tschira Institute for Computational Cardiology, Section of Bioinformatics and Systems Cardiology, University Hospital, D-96120 Heidelberg, Germany
| | - Michael F Jantsch
- Center of Anatomy and Cell Biology, Department of Cell and Developmental Biology, Medical University of Vienna, A-1090 Vienna, Austria
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21
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Bajad P, Ebner F, Amman F, Szabó B, Kapoor U, Manjali G, Hildebrandt A, Janisiw MP, Jantsch MF. An internal deletion of ADAR rescued by MAVS deficiency leads to a minute phenotype. Nucleic Acids Res 2020; 48:3286-3303. [PMID: 31956894 PMCID: PMC7102943 DOI: 10.1093/nar/gkaa025] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 12/27/2019] [Accepted: 01/16/2020] [Indexed: 12/22/2022] Open
Abstract
The RNA-editing protein ADAR is essential for early development in the mouse. Genetic evidence suggests that A to I editing marks endogenous RNAs as ‘self’. Today, different Adar knockout alleles have been generated that show a common phenotype of apoptosis, liver disintegration, elevated immune response and lethality at E12.5. All the Adar knockout alleles can be rescued by a concomitant deletion of the innate immunity genes Mavs or Ifih1 (MDA5), albeit to different extents. This suggests multiple functions of ADAR. We analyze AdarΔ7-9 mice that show a unique growth defect phenotype when rescued by Mavs. We show that AdarΔ7-9 can form a truncated, unstable, editing deficient protein that is mislocalized. Histological and hematologic analysis of these mice indicate multiple tissue- and hematopoietic defects. Gene expression profiling shows dysregulation of Rps3a1 and Rps3a3 in rescued AdarΔ7-9. Consistently, a distortion in 40S and 60S ribosome ratios is observed in liver cells. This dysregulation is also seen in AdarΔ2-13; Mavs−/− but not in AdarE861A/E861A; Ifih1−/− mice, suggesting editing-independent functions of ADAR in regulating expression levels of Rps3a1 and Rps3a3. In conclusion, our study demonstrates the importance of ADAR in post-natal development which cannot be compensated by ADARB1.
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Affiliation(s)
- Prajakta Bajad
- Department of Cell & Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
| | - Florian Ebner
- Department of Cell & Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
| | - Fabian Amman
- Department of Cell & Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria.,Institute of Theoretical Biochemistry, University of Vienna, Währinger Strasse 17, A-1090 Vienna, Austria
| | - Brigitta Szabó
- Department of Cell & Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
| | - Utkarsh Kapoor
- Department of Cell & Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
| | - Greeshma Manjali
- Department of Cell & Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
| | - Alwine Hildebrandt
- Department of Cell & Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
| | - Michael P Janisiw
- Department of Cell & Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
| | - Michael F Jantsch
- Department of Cell & Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
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22
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Jain M, Jantsch MF, Licht K. The Editor's I on Disease Development. Trends Genet 2019; 35:903-913. [PMID: 31648814 DOI: 10.1016/j.tig.2019.09.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 09/26/2019] [Accepted: 09/27/2019] [Indexed: 12/12/2022]
Abstract
Adenosine-to-inosine (A-to-I) editing of RNA leads to deamination of adenosine to inosine. Inosine is interpreted as guanosine by the cellular machinery, thus altering the coding, folding, splicing, or transport of transcripts. A-to-I editing is tightly regulated. Altered editing has severe consequences for human health and can cause interferonopathies, neurological disorders, and cardiovascular disease, as well as impacting on cancer progression. ADAR1-mediated RNA editing plays an important role in antiviral immunity and is essential for distinguishing between endogenous and viral RNA, thereby preventing autoimmune disorders. Interestingly, A-to-I editing can be used not only to correct genomic mutations at the RNA level but also to modulate tumor antigenicity with large therapeutic potential. We highlight recent developments in the field, focusing on cancer and other human diseases.
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Affiliation(s)
- Mamta Jain
- Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
| | - Michael F Jantsch
- Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria.
| | - Konstantin Licht
- Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
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23
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Licht K, Kapoor U, Amman F, Picardi E, Martin D, Bajad P, Jantsch MF. A high resolution A-to-I editing map in the mouse identifies editing events controlled by pre-mRNA splicing. Genome Res 2019; 29:1453-1463. [PMID: 31427386 PMCID: PMC6724681 DOI: 10.1101/gr.242636.118] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2018] [Accepted: 07/25/2019] [Indexed: 11/25/2022]
Abstract
Pre-mRNA-splicing and adenosine to inosine (A-to-I) RNA-editing occur mostly cotranscriptionally. During A-to-I editing, a genomically encoded adenosine is deaminated to inosine by adenosine deaminases acting on RNA (ADARs). Editing-competent stems are frequently formed between exons and introns. Consistently, studies using reporter assays have shown that splicing efficiency can affect editing levels. Here, we use Nascent-seq and identify ∼90,000 novel A-to-I editing events in the mouse brain transcriptome. Most novel sites are located in intronic regions. Unlike previously assumed, we show that both ADAR (ADAR1) and ADARB1 (ADAR2) can edit repeat elements and regular transcripts to the same extent. We find that inhibition of splicing primarily increases editing levels at hundreds of sites, suggesting that reduced splicing efficiency extends the exposure of intronic and exonic sequences to ADAR enzymes. Lack of splicing factors NOVA1 or NOVA2 changes global editing levels, demonstrating that alternative splicing factors can modulate RNA editing. Finally, we show that intron retention rates correlate with editing levels across different brain tissues. We therefore demonstrate that splicing efficiency is a major factor controlling tissue-specific differences in editing levels.
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Affiliation(s)
- Konstantin Licht
- Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Utkarsh Kapoor
- Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Fabian Amman
- Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria.,Institute of Theoretical Biochemistry, University of Vienna, A-1090 Vienna, Austria
| | - Ernesto Picardi
- Department of Biosciences, Biotechnologies, and Biopharmaceutics, University of Bari, I-70126 Bari, Italy.,Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, I-70126 Bari, Italy
| | - David Martin
- Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Prajakta Bajad
- Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Michael F Jantsch
- Center for Anatomy and Cell Biology, Medical University of Vienna, A-1090 Vienna, Austria
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TAK-137, an AMPA-R potentiator with little agonistic effect, has a wide therapeutic window. Neuropsychopharmacology 2019; 44:961-970. [PMID: 30209408 PMCID: PMC6461786 DOI: 10.1038/s41386-018-0213-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 08/27/2018] [Accepted: 09/03/2018] [Indexed: 01/08/2023]
Abstract
Activation of α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor (AMPA-R) is a promising strategy to treat psychiatric and neurological diseases if issues of bell-shaped response and narrow safety margin against seizure can be overcome. Here, we show that structural interference at Ser743 in AMPA-R is a key to lower the agonistic effect of AMPA-R potentiators containing dihydropyridothiadiazine 2,2-dioxides skeleton. With this structural insight, TAK-137, 9-(4-phenoxyphenyl)-3,4-dihydropyrido[2,1-c][1,2,4]thiadiazine 2,2-dioxide, was discovered as a novel AMPA-R potentiator with a lower agonistic effect than an AMPA-R potentiator LY451646 ((R)-N-(2-(4'-cyanobiphenyl-4-yl)propyl)propane-2-sulfonamide) in rat primary neurons. TAK-137 induced brain-derived neurotrophic factor in neurons in rodents and potently improved cognition in both rats and monkeys. Compared to LY451646, TAK-137 had a wider safety margin against seizure in rats. TAK-137 enhanced neural progenitor proliferation over a broader range of doses in rodents. Thus, TAK-137 is a promising AMPA-R potentiator with potent procognitive effects and lower risks of bell-shaped response and seizure. These data may open the door for the development of AMPA-R potentiators as therapeutic drugs for psychiatric and neurological diseases.
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25
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Hsiao YHE, Bahn JH, Yang Y, Lin X, Tran S, Yang EW, Quinones-Valdez G, Xiao X. RNA editing in nascent RNA affects pre-mRNA splicing. Genome Res 2018; 28:812-823. [PMID: 29724793 PMCID: PMC5991522 DOI: 10.1101/gr.231209.117] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 04/26/2018] [Indexed: 12/21/2022]
Abstract
In eukaryotes, nascent RNA transcripts undergo an intricate series of RNA processing steps to achieve mRNA maturation. RNA editing and alternative splicing are two major RNA processing steps that can introduce significant modifications to the final gene products. By tackling these processes in isolation, recent studies have enabled substantial progress in understanding their global RNA targets and regulatory pathways. However, the interplay between individual steps of RNA processing, an essential aspect of gene regulation, remains poorly understood. By sequencing the RNA of different subcellular fractions, we examined the timing of adenosine-to-inosine (A-to-I) RNA editing and its impact on alternative splicing. We observed that >95% A-to-I RNA editing events occurred in the chromatin-associated RNA prior to polyadenylation. We report about 500 editing sites in the 3' acceptor sequences that can alter splicing of the associated exons. These exons are highly conserved during evolution and reside in genes with important cellular function. Furthermore, we identified a second class of exons whose splicing is likely modulated by RNA secondary structures that are recognized by the RNA editing machinery. The genome-wide analyses, supported by experimental validations, revealed remarkable interplay between RNA editing and splicing and expanded the repertoire of functional RNA editing sites.
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Affiliation(s)
| | - Jae Hoon Bahn
- Department of Integrative Biology and Physiology, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Yun Yang
- Department of Integrative Biology and Physiology, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Xianzhi Lin
- Department of Integrative Biology and Physiology, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Stephen Tran
- Bioinformatics Interdepartmental Program, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Ei-Wen Yang
- Department of Integrative Biology and Physiology, University of California Los Angeles, Los Angeles, California 90095, USA
| | | | - Xinshu Xiao
- Department of Bioengineering
- Department of Integrative Biology and Physiology, University of California Los Angeles, Los Angeles, California 90095, USA
- Bioinformatics Interdepartmental Program, University of California Los Angeles, Los Angeles, California 90095, USA
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, California 90095, USA
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26
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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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Kunugi A, Tajima Y, Kuno H, Sogabe S, Kimura H. HBT1, a Novel AMPA Receptor Potentiator with Lower Agonistic Effect, Avoided Bell-Shaped Response in In Vitro BDNF Production. J Pharmacol Exp Ther 2018; 364:377-389. [PMID: 29298820 DOI: 10.1124/jpet.117.245050] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 12/28/2017] [Indexed: 11/22/2022] Open
Abstract
α-Amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptor (AMPA-R) potentiators with brain-derived neurotrophic factor (BDNF)-induction potential could be promising as therapeutic drugs for neuropsychiatric and neurologic disorders. However, AMPA-R potentiators such as LY451646 have risks of narrow bell-shaped responses in pharmacological effects, including in vivo BDNF induction. Interestingly, LY451646 and LY451395, other AMPA-R potentiators, showed agonistic effects and exhibited bell-shaped responses in the BDNF production in primary neurons. We hypothesized that the agonistic property is related to the bell-shaped response and endeavored to discover novel AMPA-R potentiators with lower agonistic effects. LY451395 showed an agonistic effect in primary neurons, but not in a cell line expressing AMPA-Rs, in Ca2+ influx assays; thus, we used a Ca2+ influx assay in primary neurons and, from a chemical library, discovered two AMPA-R potentiators with lower agonistic effects: 2-(((5-methyl-3-(trifluoromethyl)-1H-pyrazol-1-yl)acetyl)amino)-4,5,6,7-tetrahydro-1-benzothiophene-3-carboxamide (HBT1) and (3S)-1-(4-tert-butylphenyl)-N-((1R)-2-(dimethylamino)-1-phenylethyl)-3-isobutyl-2-oxopyrrolidine-3-carboxamide (OXP1). In a patch-clamp study using primary neurons, HBT1 showed little agonistic effect, whereas both LY451395 and OXP1 showed remarkable agonistic effects. HBT1, but not OXP1, did not show remarkable bell-shaped response in BDNF production in primary neurons. HBT1 bound to the ligand-binding domain (LBD) of AMPA-R in a glutamate-dependent manner. The mode of HBT1 and LY451395 binding to a pocket in the LBD of AMPA-R differed: HBT1, but not LY451395, formed hydrogen bonds with S518 in the LBD. OXP1 may bind to a cryptic binding pocket on AMPA-R. Lower agonistic profile of HBT1 may associate with its lower risks of bell-shaped responses in BDNF production in primary neurons.
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Affiliation(s)
- Akiyoshi Kunugi
- Research, Takeda Pharmaceutical Company Limited, Fujisawa, Kanagawa, Japan
| | - Yasukazu Tajima
- Research, Takeda Pharmaceutical Company Limited, Fujisawa, Kanagawa, Japan
| | - Haruhiko Kuno
- Research, Takeda Pharmaceutical Company Limited, Fujisawa, Kanagawa, Japan
| | - Satoshi Sogabe
- Research, Takeda Pharmaceutical Company Limited, Fujisawa, Kanagawa, Japan
| | - Haruhide Kimura
- Research, Takeda Pharmaceutical Company Limited, Fujisawa, Kanagawa, Japan
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28
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Abstract
One of the most prevalent forms of post-transcritpional RNA modification is the conversion of adenosine nucleosides to inosine (A-to-I), mediated by the ADAR family of enzymes. The functional requirement and regulatory landscape for the majority of A-to-I editing events are, at present, uncertain. Recent studies have identified key in vivo functions of ADAR enzymes, informing our understanding of the biological importance of A-to-I editing. Large-scale studies have revealed how editing is regulated both in cis and in trans. This review will explore these recent studies and how they broaden our understanding of the functions and regulation of ADAR-mediated RNA editing.
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Affiliation(s)
- Carl R Walkley
- St Vincent's Institute of Medical Research, Fitzroy, Victoria, 3065, Australia. .,Department of Medicine, St Vincent's Hospital, University of Melbourne, Fitzroy, Victoria, 3065, Australia.
| | - Jin Billy Li
- Department of Genetics, Stanford University, Stanford, CA, 94305, USA.
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29
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Wen W, Lin CY, Niu L. R/G editing in GluA2R flop modulates the functional difference between GluA1 flip and flop variants in GluA1/2R heteromeric channels. Sci Rep 2017; 7:13654. [PMID: 29057893 PMCID: PMC5651858 DOI: 10.1038/s41598-017-13233-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 09/20/2017] [Indexed: 12/12/2022] Open
Abstract
In α-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA) receptors, RNA editing and alternative splicing generate sequence variants, and those variants, as in GluA2-4 AMPA receptor subunits, generally show different properties. Yet, earlier studies have shown that the alternatively spliced, flip and flop variants of GluA1 AMPA receptor subunit exhibit no functional difference in homomeric channel form. Using a laser-pulse photolysis technique, combined with whole-cell recording, we measured the rate of channel opening, among other kinetic properties, for a series of AMPA channels with different arginine/glycine (R/G) editing and flip/flop status. We find that R/G editing in the GluA2 subunit modulates the channel properties in both homomeric (GluA2Q) and complex (GluA2Q/2R and GluA1/2R) channel forms. However, R/G editing is only effective in flop channels. Specifically, editing at the R/G site on the GluA2R flop isoform accelerates the rate of channel opening and desensitization for GluA1/2R channels more pronouncedly with the GluA1 being in the flop form than in the flip form; yet R/G editing has no effect on either channel-closing rate or EC50. Our results suggest R/G editing via GluA2R serve as a regulatory mechanism to modulate the function of GluA2R-containing, native receptors involved in fast excitatory synaptic transmission.
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Affiliation(s)
- Wei Wen
- Department of Chemistry, and Center for Neuroscience Research, University at Albany, SUNY, Albany, New York, 12222, United States
| | - Chi-Yen Lin
- Department of Chemistry, and Center for Neuroscience Research, University at Albany, SUNY, Albany, New York, 12222, United States
| | - Li Niu
- Department of Chemistry, and Center for Neuroscience Research, University at Albany, SUNY, Albany, New York, 12222, United States.
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30
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Gallo A, Vukic D, Michalík D, O’Connell MA, Keegan LP. ADAR RNA editing in human disease; more to it than meets the I. Hum Genet 2017; 136:1265-1278. [DOI: 10.1007/s00439-017-1837-0] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 08/22/2017] [Indexed: 01/08/2023]
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Protein recoding by ADAR1-mediated RNA editing is not essential for normal development and homeostasis. Genome Biol 2017; 18:166. [PMID: 28874170 PMCID: PMC5585977 DOI: 10.1186/s13059-017-1301-4] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 08/15/2017] [Indexed: 02/07/2023] Open
Abstract
Background Adenosine-to-inosine (A-to-I) editing of dsRNA by ADAR proteins is a pervasive epitranscriptome feature. Tens of thousands of A-to-I editing events are defined in the mouse, yet the functional impact of most is unknown. Editing causing protein recoding is the essential function of ADAR2, but an essential role for recoding by ADAR1 has not been demonstrated. ADAR1 has been proposed to have editing-dependent and editing-independent functions. The relative contribution of these in vivo has not been clearly defined. A critical function of ADAR1 is editing of endogenous RNA to prevent activation of the dsRNA sensor MDA5 (Ifih1). Outside of this, how ADAR1 editing contributes to normal development and homeostasis is uncertain. Results We describe the consequences of ADAR1 editing deficiency on murine homeostasis. Adar1E861A/E861AIfih1-/- mice are strikingly normal, including their lifespan. There is a mild, non-pathogenic innate immune activation signature in the Adar1E861A/E861AIfih1-/- mice. Assessing A-to-I editing across adult tissues demonstrates that outside of the brain, ADAR1 performs the majority of editing and that ADAR2 cannot compensate in its absence. Direct comparison of the Adar1-/- and Adar1E861A/E861A alleles demonstrates a high degree of concordance on both Ifih1+/+ and Ifih1-/- backgrounds, suggesting no substantial contribution from ADAR1 editing-independent functions. Conclusions These analyses demonstrate that the lifetime absence of ADAR1-editing is well tolerated in the absence of MDA5. We conclude that protein recoding arising from ADAR1-mediated editing is not essential for organismal homeostasis. Additionally, the phenotypes associated with loss of ADAR1 are the result of RNA editing and MDA5-dependent functions. Electronic supplementary material The online version of this article (doi:10.1186/s13059-017-1301-4) contains supplementary material, which is available to authorized users.
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32
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Filippini A, Bonini D, Lacoux C, Pacini L, Zingariello M, Sancillo L, Bosisio D, Salvi V, Mingardi J, La Via L, Zalfa F, Bagni C, Barbon A. Absence of the Fragile X Mental Retardation Protein results in defects of RNA editing of neuronal mRNAs in mouse. RNA Biol 2017. [PMID: 28640668 PMCID: PMC5785225 DOI: 10.1080/15476286.2017.1338232] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
The fragile X syndrome (FXS), the most common form of inherited intellectual disability, is due to the absence of FMRP, a protein regulating RNA metabolism. Recently, an unexpected function of FMRP in modulating the activity of Adenosine Deaminase Acting on RNA (ADAR) enzymes has been reported both in Drosophila and Zebrafish. ADARs are RNA-binding proteins that increase transcriptional complexity through a post-transcriptional mechanism called RNA editing. To evaluate the ADAR2-FMRP interaction in mammals we analyzed several RNA editing re-coding sites in the fmr1 knockout (KO) mice. Ex vivo and in vitro analysis revealed that absence of FMRP leads to an increase in the editing levels of brain specific mRNAs, indicating that FMRP might act as an inhibitor of editing activity. Proximity Ligation Assay (PLA) in mouse primary cortical neurons and in non-neuronal cells revealed that ADAR2 and FMRP co-localize in the nucleus. The ADAR2-FMRP co-localization was further observed by double-immunogold Electron Microscopy (EM) in the hippocampus. Moreover, ADAR2-FMRP interaction appeared to be RNA independent. Because changes in the editing pattern are associated with neuropsychiatric and neurodevelopmental disorders, we propose that the increased editing observed in the fmr1-KO mice might contribute to the FXS molecular phenotypes.
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Affiliation(s)
- Alice Filippini
- a Biology and Genetic Division; Department of Molecular and Translational Medicine; University of Brescia ; Brescia , Italy
| | - Daniela Bonini
- a Biology and Genetic Division; Department of Molecular and Translational Medicine; University of Brescia ; Brescia , Italy
| | - Caroline Lacoux
- b Department of Biomedicine and Prevention , University of Rome Tor Vergata , Rome , Italy
| | - Laura Pacini
- b Department of Biomedicine and Prevention , University of Rome Tor Vergata , Rome , Italy
| | - Maria Zingariello
- c Department of Medicine , Campus Bio-Medico University , via Álvaro del Portillo 21, Rome , Italy
| | - Laura Sancillo
- d Department of Medicine and Aging Sciences, Section of Human Morphology , University G. D'Annunzio of Chieti-Pescara , Chieti , Italy
| | - Daniela Bosisio
- e Immunology Unit; Department of Molecular and Translational Medicine; University of Brescia ; Brescia , Italy
| | - Valentina Salvi
- e Immunology Unit; Department of Molecular and Translational Medicine; University of Brescia ; Brescia , Italy
| | - Jessica Mingardi
- a Biology and Genetic Division; Department of Molecular and Translational Medicine; University of Brescia ; Brescia , Italy
| | - Luca La Via
- a Biology and Genetic Division; Department of Molecular and Translational Medicine; University of Brescia ; Brescia , Italy
| | - Francesca Zalfa
- c Department of Medicine , Campus Bio-Medico University , via Álvaro del Portillo 21, Rome , Italy
| | - Claudia Bagni
- b Department of Biomedicine and Prevention , University of Rome Tor Vergata , Rome , Italy.,f VIB Center for the Biology of Disease and Center for Human Genetics , Leuven , Belgium.,g Department of Fundamental Neuroscience , University of Lausanne , Lausanne , Switzerland
| | - Alessandro Barbon
- a Biology and Genetic Division; Department of Molecular and Translational Medicine; University of Brescia ; Brescia , Italy
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33
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Aljohi HA, Liu W, Lin Q, Yu J, Hu S. ISVASE: identification of sequence variant associated with splicing event using RNA-seq data. BMC Bioinformatics 2017; 18:320. [PMID: 28659141 PMCID: PMC5490186 DOI: 10.1186/s12859-017-1732-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 06/15/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Exon recognition and splicing precisely and efficiently by spliceosome is the key to generate mature mRNAs. About one third or a half of disease-related mutations affect RNA splicing. Software PVAAS has been developed to identify variants associated with aberrant splicing by directly using RNA-seq data. However, it bases on the assumption that annotated splicing site is normal splicing, which is not true in fact. RESULTS We develop the ISVASE, a tool for specifically identifying sequence variants associated with splicing events (SVASE) by using RNA-seq data. Comparing with PVAAS, our tool has several advantages, such as multi-pass stringent rule-dependent filters and statistical filters, only using split-reads, independent sequence variant identification in each part of splicing (junction), sequence variant detection for both of known and novel splicing event, additional exon-exon junction shift event detection if known splicing events provided, splicing signal evaluation, known DNA mutation and/or RNA editing data supported, higher precision and consistency, and short running time. Using a realistic RNA-seq dataset, we performed a case study to illustrate the functionality and effectiveness of our method. Moreover, the output of SVASEs can be used for downstream analysis such as splicing regulatory element study and sequence variant functional analysis. CONCLUSIONS ISVASE is useful for researchers interested in sequence variants (DNA mutation and/or RNA editing) associated with splicing events. The package is freely available at https://sourceforge.net/projects/isvase/ .
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Affiliation(s)
- Hasan Awad Aljohi
- Joint Center for Genomics Research (JCGR), King Abdulaziz City for Science and Technology and Chinese Academy of Sciences, Prince Turki Road, Riyadh, 11442, Saudi Arabia
| | - Wanfei Liu
- Joint Center for Genomics Research (JCGR), King Abdulaziz City for Science and Technology and Chinese Academy of Sciences, Prince Turki Road, Riyadh, 11442, Saudi Arabia.,CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, NO.1 Beichen West Road, Chaoyang District, Beijing, 100101, China.,Current address: Grail Scientific Co. Ltd., Room 26-1, Build A, Meilong Jiayuan, NO. 80 South Nanjing Street, Heping District, Shenyang, Liaoning, 110000, China
| | - Qiang Lin
- Joint Center for Genomics Research (JCGR), King Abdulaziz City for Science and Technology and Chinese Academy of Sciences, Prince Turki Road, Riyadh, 11442, Saudi Arabia.,CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, NO.1 Beichen West Road, Chaoyang District, Beijing, 100101, China
| | - Jun Yu
- Joint Center for Genomics Research (JCGR), King Abdulaziz City for Science and Technology and Chinese Academy of Sciences, Prince Turki Road, Riyadh, 11442, Saudi Arabia. .,CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, NO.1 Beichen West Road, Chaoyang District, Beijing, 100101, China.
| | - Songnian Hu
- Joint Center for Genomics Research (JCGR), King Abdulaziz City for Science and Technology and Chinese Academy of Sciences, Prince Turki Road, Riyadh, 11442, Saudi Arabia. .,CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, NO.1 Beichen West Road, Chaoyang District, Beijing, 100101, China.
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34
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Abstract
Inosine is one of the most common modifications found in human RNAs and the Adenosine Deaminases that act on RNA (ADARs) are the main enzymes responsible for its production. ADARs were first discovered in the 1980s and since then our understanding of ADARs has advanced tremendously. For instance, it is now known that defective ADAR function can cause human diseases. Furthermore, recently solved crystal structures of the human ADAR2 deaminase bound to RNA have provided insights regarding the catalytic and substrate recognition mechanisms. In this chapter, we describe the occurrence of inosine in human RNAs and the newest perspective on the ADAR family of enzymes, including their substrate recognition, catalytic mechanism, regulation as well as the consequences of A-to-I editing, and their relation to human diseases.
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35
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Abstract
Adenosine deaminases acting on RNA (ADARs) are zinc-containing enzymes that deaminate adenosine bases to inosines within dsRNA regions in transcripts. In short, structured dsRNA hairpins individual adenosine bases may be targeted specifically and edited with up to one hundred percent efficiency, leading to the production of alternative protein variants. However, the majority of editing events occur within longer stretches of dsRNA formed by pairing of repetitive sequences. Here, many different adenosine bases are potential targets but editing efficiency is usually much lower. Recent work shows that ADAR-mediated RNA editing is also required to prevent aberrant activation of antiviral innate immune sensors that detect viral dsRNA in the cytoplasm. Missense mutations in the ADAR1 RNA editing enzyme cause a fatal auto-inflammatory disease, Aicardi–Goutières syndrome (AGS) in affected children. In addition RNA editing by ADARs has been observed to increase in many cancers and also can contribute to vascular disease. Thus the role of RNA editing in the progression of various diseases can no longer be ignored. The ability of ADARs to alter the sequence of RNAs has also been used to artificially target model RNAs in vitro and in cells for RNA editing. Potentially this approach may be used to repair genetic defects and to alter genetic information at the RNA level. In this review we focus on the role of ADARs in disease development and progression and on their potential use to artificially modify RNAs in a targeted manner.
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Affiliation(s)
- Prajakta Bajad
- a Medical University of Vienna, Center of Anatomy and Cell Biology , Department of Cell- and Developmental Biology , Schwarzspanierstrasse, Vienna , Austria
| | - Michael F Jantsch
- a Medical University of Vienna, Center of Anatomy and Cell Biology , Department of Cell- and Developmental Biology , Schwarzspanierstrasse, Vienna , Austria
| | - Liam Keegan
- b CEITEC at Masaryk University , Kamenice, Czech Republic
| | - Mary O'Connell
- b CEITEC at Masaryk University , Kamenice, Czech Republic
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Dillman AA, Cookson MR, Galter D. ADAR2 affects mRNA coding sequence edits with only modest effects on gene expression or splicing in vivo. RNA Biol 2016; 13:15-24. [PMID: 26669816 DOI: 10.1080/15476286.2015.1110675] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Adenosine deaminases bind double stranded RNA and convert adenosine to inosine. Editing creates multiple isoforms of neurotransmitter receptors, such as with Gria2. Adar2 KO mice die of seizures shortly after birth, but if the Gria2 Q/R editing site is mutated to mimic the edited version then the animals are viable. We performed RNA-Seq on frontal cortices of Adar2(-/-) Gria2(R/R) mice and littermates. We found 56 editing sites with significantly diminished editing levels in Adar2 deficient animals with the majority in coding regions. Only two genes and 3 exons showed statistically significant differences in expression levels. This work illustrates that ADAR2 is important in site-specific changes of protein coding sequences but has relatively modest effects on gene expression and splicing in the adult mouse frontal cortex.
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Affiliation(s)
- Allissa A Dillman
- a Cell Biology and Gene Expression Section, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health , Bethesda , MD , USA.,b Department of Neuroscience , Karolinska Institute , 171 77 Stockholm , Sweden.,c Center for Cancer Research, Laboratory of Receptor Biology and Gene Expression, National Cancer Institute , Bethesda , MD , USA
| | - Mark R Cookson
- a Cell Biology and Gene Expression Section, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health , Bethesda , MD , USA
| | - Dagmar Galter
- b Department of Neuroscience , Karolinska Institute , 171 77 Stockholm , Sweden
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Filippini A, Bonini D, La Via L, Barbon A. The Good and the Bad of Glutamate Receptor RNA Editing. Mol Neurobiol 2016; 54:6795-6805. [DOI: 10.1007/s12035-016-0201-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 10/11/2016] [Indexed: 12/15/2022]
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Dynamic regulation of RNA editing in human brain development and disease. Nat Neurosci 2016; 19:1093-9. [DOI: 10.1038/nn.4337] [Citation(s) in RCA: 130] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 05/27/2016] [Indexed: 02/07/2023]
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Licht K, Kapoor U, Mayrhofer E, Jantsch MF. Adenosine to Inosine editing frequency controlled by splicing efficiency. Nucleic Acids Res 2016; 44:6398-408. [PMID: 27112566 PMCID: PMC5291252 DOI: 10.1093/nar/gkw325] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 04/14/2016] [Indexed: 11/22/2022] Open
Abstract
Alternative splicing and adenosine to inosine (A to I) RNA-editing are major factors leading to co- and post-transcriptional modification of genetic information. Both, A to I editing and splicing occur in the nucleus. As editing sites are frequently defined by exon–intron basepairing, mRNA splicing efficiency should affect editing levels. Moreover, splicing rates affect nuclear retention and will therefore also influence the exposure of pre-mRNAs to the editing-competent nuclear environment. Here, we systematically test the influence of splice rates on RNA-editing using reporter genes but also endogenous substrates. We demonstrate for the first time that the extent of editing is controlled by splicing kinetics when editing is guided by intronic elements. In contrast, editing sites that are exclusively defined by exonic structures are almost unaffected by the splicing efficiency of nearby introns. In addition, we show that editing levels in pre- and mature mRNAs do not match. This phenomenon can in part be explained by the editing state of an RNA influencing its splicing rate but also by the binding of the editing enzyme ADAR that interferes with splicing.
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Affiliation(s)
- Konstantin Licht
- Department of Cell- and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna 1090, Austria
| | - Utkarsh Kapoor
- Department of Cell- and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna 1090, Austria
| | - Elisa Mayrhofer
- Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, Vienna 1030, Austria
| | - Michael F Jantsch
- Department of Cell- and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna 1090, Austria Department of Medical Biochemistry, Max F. Perutz Laboratories, Medical University of Vienna, Vienna 1030, Austria
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RNA Editing: A Contributor to Neuronal Dynamics in the Mammalian Brain. Trends Genet 2016; 32:165-175. [PMID: 26803450 DOI: 10.1016/j.tig.2015.12.005] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 12/21/2015] [Accepted: 12/22/2015] [Indexed: 01/10/2023]
Abstract
Post-transcriptional RNA modification by adenosine to inosine (A-to-I) editing expands the functional output of many important neuronally expressed genes. The mechanism provides flexibility in the proteome by expanding the variety of isoforms, and is a requisite for neuronal function. Indeed, targets for editing include key mediators of synaptic transmission with an overall significant effect on neuronal signaling. In addition, editing influences splice-site choice and miRNA targeting capacity, and thereby regulates neuronal gene expression. Editing efficiency at most of these sites increases during neuronal differentiation and brain maturation in a spatiotemporal manner. This editing-induced dynamics in the transcriptome is essential for normal brain development, and we are only beginning to understand its role in neuronal function. In this review we discuss the impact of RNA editing in the brain, with special emphasis on the physiological consequences for neuronal development and plasticity.
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Tajaddod M, Jantsch MF, Licht K. The dynamic epitranscriptome: A to I editing modulates genetic information. Chromosoma 2015; 125:51-63. [PMID: 26148686 PMCID: PMC4761006 DOI: 10.1007/s00412-015-0526-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 06/22/2015] [Accepted: 06/24/2015] [Indexed: 02/03/2023]
Abstract
Adenosine to inosine editing (A to I editing) is a cotranscriptional process that contributes to transcriptome complexity by deamination of adenosines to inosines. Initially, the impact of A to I editing has been described for coding targets in the nervous system. Here, A to I editing leads to recoding and changes of single amino acids since inosine is normally interpreted as guanosine by cellular machines. However, more recently, new roles for A to I editing have emerged: Editing was shown to influence splicing and is found massively in Alu elements. Moreover, A to I editing is required to modulate innate immunity. We summarize the multiple ways in which A to I editing generates transcriptome variability and highlight recent findings in the field.
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Affiliation(s)
- Mansoureh Tajaddod
- Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, Dr. Bohr Gasse 9/5, A-1030, Vienna, Austria
| | - Michael F Jantsch
- Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, Dr. Bohr Gasse 9/5, A-1030, Vienna, Austria. .,Department of Cell Biology, Center of Cell Biology and Anatomy, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090, Vienna, Austria.
| | - Konstantin Licht
- Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, Dr. Bohr Gasse 9/5, A-1030, Vienna, Austria.
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Solomon O, Bazak L, Levanon EY, Amariglio N, Unger R, Rechavi G, Eyal E. Characterizing of functional human coding RNA editing from evolutionary, structural, and dynamic perspectives. Proteins 2014; 82:3117-31. [DOI: 10.1002/prot.24672] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 07/28/2014] [Accepted: 08/11/2014] [Indexed: 12/29/2022]
Affiliation(s)
- Oz Solomon
- Cancer Research Center; Chaim Sheba Medical Center; Tel Hashomer 52621 Ramat Gan Israel
- The Everard & Mina Goodman Faculty of Life Sciences; Bar-Ilan University; Ramat Gan 52900 Israel
| | - Lily Bazak
- The Everard & Mina Goodman Faculty of Life Sciences; Bar-Ilan University; Ramat Gan 52900 Israel
| | - Erez Y. Levanon
- The Everard & Mina Goodman Faculty of Life Sciences; Bar-Ilan University; Ramat Gan 52900 Israel
| | - Ninette Amariglio
- Cancer Research Center; Chaim Sheba Medical Center; Tel Hashomer 52621 Ramat Gan Israel
| | - Ron Unger
- The Everard & Mina Goodman Faculty of Life Sciences; Bar-Ilan University; Ramat Gan 52900 Israel
| | - Gideon Rechavi
- Cancer Research Center; Chaim Sheba Medical Center; Tel Hashomer 52621 Ramat Gan Israel
- Sackler School of Medicine; Tel Aviv University; Tel Aviv 69978 Israel
| | - Eran Eyal
- Cancer Research Center; Chaim Sheba Medical Center; Tel Hashomer 52621 Ramat Gan Israel
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Liu H, Ma CP, Chen YT, Schuyler SC, Chang KP, Tan BCM. Functional Impact of RNA editing and ADARs on regulation of gene expression: perspectives from deep sequencing studies. Cell Biosci 2014; 4:44. [PMID: 25949793 PMCID: PMC4422215 DOI: 10.1186/2045-3701-4-44] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 07/14/2014] [Indexed: 11/13/2022] Open
Abstract
Cells regulate gene expression at multiple levels leading to a balance between robustness and complexity within their proteome. One core molecular step contributing to this important balance during metazoan gene expression is RNA editing, such as the co-transcriptional recoding of RNA transcripts catalyzed by the adenosine deaminse acting on RNA (ADAR) family of enzymes. Understanding of the adenosine-to-inosine RNA editing process has been broadened considerably by the next generation sequencing (NGS) technology, which allows for in-depth demarcation of an RNA editome at nucleotide resolution. However, critical issues remain unresolved with regard to how RNA editing cooperates with other transcript-associated events to underpin regulated gene expression. Here we review the growing body of evidence, provided by recent NGS-based studies, that links RNA editing to other mechanisms of post-transcriptional RNA processing and gene expression regulation including alternative splicing, transcript stability and localization, and the biogenesis and function of microRNAs (miRNAs). We also discuss the possibility that systematic integration of NGS data may be employed to establish the rules of an “RNA editing code”, which may give us new insights into the functional consequences of RNA editing.
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Affiliation(s)
- Hsuan Liu
- Graduate Institute of Biomedical Sciences, Tao-Yuan, Taiwan ; Department of Biochemistry, Tao-Yuan, Taiwan ; Molecular Medicine Research Center, Chang Gung University, Tao-Yuan, Taiwan
| | - Chung-Pei Ma
- Graduate Institute of Biomedical Sciences, Tao-Yuan, Taiwan
| | - Yi-Tung Chen
- Graduate Institute of Biomedical Sciences, Tao-Yuan, Taiwan
| | - Scott C Schuyler
- Graduate Institute of Biomedical Sciences, Tao-Yuan, Taiwan ; Department of Biomedical Sciences, College of Medicine, Tao-Yuan, Taiwan
| | - Kai-Ping Chang
- Molecular Medicine Research Center, Chang Gung University, Tao-Yuan, Taiwan ; Department of Otolaryngology, Chang Gung Memorial Hospital at Lin-Kuo, Tao-Yuan, Taiwan
| | - Bertrand Chin-Ming Tan
- Graduate Institute of Biomedical Sciences, Tao-Yuan, Taiwan ; Department of Biomedical Sciences, College of Medicine, Tao-Yuan, Taiwan ; Molecular Medicine Research Center, Chang Gung University, Tao-Yuan, Taiwan
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Mo F, Wyatt AW, Sun Y, Brahmbhatt S, McConeghy BJ, Wu C, Wang Y, Gleave ME, Volik SV, Collins CC. Systematic identification and characterization of RNA editing in prostate tumors. PLoS One 2014; 9:e101431. [PMID: 25036877 PMCID: PMC4103770 DOI: 10.1371/journal.pone.0101431] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 06/05/2014] [Indexed: 12/15/2022] Open
Abstract
RNA editing modifies the sequence of primary transcripts, potentially resulting in profound effects to RNA structure and protein-coding sequence. Recent analyses of RNA sequence data are beginning to provide insights into the distribution of RNA editing across the entire transcriptome, but there are few published matched whole genome and transcriptome sequence datasets, and designing accurate bioinformatics methodology has proven highly challenging. To further characterize the RNA editome, we analyzed 16 paired DNA-RNA sequence libraries from prostate tumor specimens, employing a comprehensive strategy to rescue low coverage sites and minimize false positives. We identified over a hundred thousand putative RNA editing events, a third of which were recurrent in two or more samples, and systematically characterized their type and distribution across the genome. Within genes the majority of events affect non-coding regions such as introns and untranslated regions (UTRs), but 546 genes had RNA editing events predicted to result in deleterious amino acid alterations. Finally, we report a potential association between RNA editing of microRNA binding sites within 3′ UTRs and increased transcript expression. These results provide a systematic characterization of the landscape of RNA editing in low coverage sequence data from prostate tumor specimens. We demonstrate further evidence for RNA editing as an important regulatory mechanism and suggest that the RNA editome should be further studied in cancer.
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Affiliation(s)
- Fan Mo
- Vancouver Prostate Centre & Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Alexander W. Wyatt
- Vancouver Prostate Centre & Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Yue Sun
- Vancouver Prostate Centre & Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Sonal Brahmbhatt
- Vancouver Prostate Centre & Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Brian J. McConeghy
- Vancouver Prostate Centre & Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Chunxiao Wu
- Vancouver Prostate Centre & Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Yuzhuo Wang
- Vancouver Prostate Centre & Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada
- Department of Experimental Therapeutics, BC Cancer Agency, Vancouver, BC, Canada
| | - Martin E. Gleave
- Vancouver Prostate Centre & Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Stanislav V. Volik
- Vancouver Prostate Centre & Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Colin C. Collins
- Vancouver Prostate Centre & Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada
- * E-mail:
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Fukuda M, Kurihara K, Yamaguchi S, Oyama Y, Deshimaru M. Improved design of hammerhead ribozyme for selective digestion of target RNA through recognition of site-specific adenosine-to-inosine RNA editing. RNA (NEW YORK, N.Y.) 2014; 20:392-405. [PMID: 24448449 PMCID: PMC3923133 DOI: 10.1261/rna.041202.113] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 12/10/2013] [Indexed: 06/03/2023]
Abstract
Adenosine-to-inosine (A-to-I) RNA editing is an endogenous regulatory mechanism involved in various biological processes. Site-specific, editing-state-dependent degradation of target RNA may be a powerful tool both for analyzing the mechanism of RNA editing and for regulating biological processes. Previously, we designed an artificial hammerhead ribozyme (HHR) for selective, site-specific RNA cleavage dependent on the A-to-I RNA editing state. In the present work, we developed an improved strategy for constructing a trans-acting HHR that specifically cleaves target editing sites in the adenosine but not the inosine state. Specificity for unedited sites was achieved by utilizing a sequence encoding the intrinsic cleavage specificity of a natural HHR. We used in vitro selection methods in an HHR library to select for an extended HHR containing a tertiary stabilization motif that facilitates HHR folding into an active conformation. By using this method, we successfully constructed highly active HHRs with unedited-specific cleavage. Moreover, using HHR cleavage followed by direct sequencing, we demonstrated that this ribozyme could cleave serotonin 2C receptor (HTR2C) mRNA extracted from mouse brain, depending on the site-specific editing state. This unedited-specific cleavage also enabled us to analyze the effect of editing state at the E and C sites on editing at other sites by using direct sequencing for the simultaneous quantification of the editing ratio at multiple sites. Our approach has the potential to elucidate the mechanism underlying the interdependencies of different editing states in substrate RNA with multiple editing sites.
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Solomon O, Oren S, Safran M, Deshet-Unger N, Akiva P, Jacob-Hirsch J, Cesarkas K, Kabesa R, Amariglio N, Unger R, Rechavi G, Eyal E. Global regulation of alternative splicing by adenosine deaminase acting on RNA (ADAR). RNA (NEW YORK, N.Y.) 2013; 19:591-604. [PMID: 23474544 PMCID: PMC3677275 DOI: 10.1261/rna.038042.112] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Alternative mRNA splicing is a major mechanism for gene regulation and transcriptome diversity. Despite the extent of the phenomenon, the regulation and specificity of the splicing machinery are only partially understood. Adenosine-to-inosine (A-to-I) RNA editing of pre-mRNA by ADAR enzymes has been linked to splicing regulation in several cases. Here we used bioinformatics approaches, RNA-seq and exon-specific microarray of ADAR knockdown cells to globally examine how ADAR and its A-to-I RNA editing activity influence alternative mRNA splicing. Although A-to-I RNA editing only rarely targets canonical splicing acceptor, donor, and branch sites, it was found to affect splicing regulatory elements (SREs) within exons. Cassette exons were found to be significantly enriched with A-to-I RNA editing sites compared with constitutive exons. RNA-seq and exon-specific microarray revealed that ADAR knockdown in hepatocarcinoma and myelogenous leukemia cell lines leads to global changes in gene expression, with hundreds of genes changing their splicing patterns in both cell lines. This global change in splicing pattern cannot be explained by putative editing sites alone. Genes showing significant changes in their splicing pattern are frequently involved in RNA processing and splicing activity. Analysis of recently published RNA-seq data from glioblastoma cell lines showed similar results. Our global analysis reveals that ADAR plays a major role in splicing regulation. Although direct editing of the splicing motifs does occur, we suggest it is not likely to be the primary mechanism for ADAR-mediated regulation of alternative splicing. Rather, this regulation is achieved by modulating trans-acting factors involved in the splicing machinery.
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Affiliation(s)
- Oz Solomon
- Cancer Research Center, Chaim Sheba Medical Center, Tel Hashomer 52621, Ramat Gan, Israel
- The Everard & Mina Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Shirley Oren
- Cancer Research Center, Chaim Sheba Medical Center, Tel Hashomer 52621, Ramat Gan, Israel
- Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Michal Safran
- Cancer Research Center, Chaim Sheba Medical Center, Tel Hashomer 52621, Ramat Gan, Israel
| | - Naamit Deshet-Unger
- Cancer Research Center, Chaim Sheba Medical Center, Tel Hashomer 52621, Ramat Gan, Israel
| | - Pinchas Akiva
- Cancer Research Center, Chaim Sheba Medical Center, Tel Hashomer 52621, Ramat Gan, Israel
- Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Jasmine Jacob-Hirsch
- Cancer Research Center, Chaim Sheba Medical Center, Tel Hashomer 52621, Ramat Gan, Israel
| | - Karen Cesarkas
- Cancer Research Center, Chaim Sheba Medical Center, Tel Hashomer 52621, Ramat Gan, Israel
| | - Reut Kabesa
- The Everard & Mina Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Ninette Amariglio
- Cancer Research Center, Chaim Sheba Medical Center, Tel Hashomer 52621, Ramat Gan, Israel
| | - Ron Unger
- The Everard & Mina Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Gideon Rechavi
- Cancer Research Center, Chaim Sheba Medical Center, Tel Hashomer 52621, Ramat Gan, Israel
- Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Eran Eyal
- Cancer Research Center, Chaim Sheba Medical Center, Tel Hashomer 52621, Ramat Gan, Israel
- Corresponding authorE-mail
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Penn AC, Balik A, Greger IH. Reciprocal regulation of A-to-I RNA editing and the vertebrate nervous system. Front Neurosci 2013; 7:61. [PMID: 23616744 PMCID: PMC3629306 DOI: 10.3389/fnins.2013.00061] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 04/02/2013] [Indexed: 12/30/2022] Open
Abstract
The fine control of molecules mediating communication in the nervous system is key to adjusting neuronal signaling during development and in maintaining the stability of established networks in the face of altered sensory input. To prevent the culmination of pathological recurrent network excitation or debilitating periods of quiescence, adaptive alterations occur in the signaling molecules and ion channels that control membrane excitability and synaptic transmission. However, rather than encoding (and thus "hardwiring") modified gene copies, the nervous systems of metazoa have opted for expanding on post-transcriptional pre-mRNA splicing by altering key encoded amino acids using a conserved mechanism of A-to-I RNA editing: the enzymatic deamination of adenosine to inosine. Inosine exhibits similar base-pairing properties to guanosine with respect to tRNA codon recognition, replication by polymerases, and RNA secondary structure (i.e.,: forming-capacity). In addition to recoding within the open reading frame, adenosine deamination also occurs with high frequency throughout the non-coding transcriptome, where it affects multiple aspects of RNA metabolism and gene expression. Here, we describe the recoding function of key RNA editing targets in the mammalian central nervous system and their potential to be regulated. We will then discuss how interactions of A-to-I editing with gene expression and alternative splicing could play a wider role in regulating the neuronal transcriptome. Finally, we will highlight the increasing complexity of this multifaceted control hub by summarizing new findings from high-throughput studies.
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Affiliation(s)
- Andrew C Penn
- Interdisciplinary Institute for Neuroscience, Université de Bordeaux, UMR 5297 Bordeaux, France ; CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297 Bordeaux, France
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Garncarz W, Tariq A, Handl C, Pusch O, Jantsch MF. A high-throughput screen to identify enhancers of ADAR-mediated RNA-editing. RNA Biol 2013; 10:192-204. [PMID: 23353575 PMCID: PMC3594278 DOI: 10.4161/rna.23208] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Adenosine to inosine deamination of RNA is widespread in metazoa. Inosines are recognized as guanosines and, therefore, this RNA-editing can influence the coding potential, localization and stability of RNAs. Therefore, RNA editing contributes to the diversification of the transcriptome in a flexible manner. The editing reaction is performed by adenosine deaminases that act on RNA (ADARs), which are essential for normal life and development in many organisms. Changes in editing levels are observed during development but also in neurological pathologies like schizophrenia, depression or tumors. Frequently, changes in editing levels are not reflected by changes in ADAR levels suggesting a regulation of enzyme activity. Until now, only a few factors are known that influence the activity of ADARs. Here we present a two-stage in vivo editing screen aimed to isolate enhancers of editing. A primary, high-throughput yeast-screen is combined with a more accurate secondary screen in mammalian cells that uses a fluorescent read-out to detect minor differences in RNA-editing. The screen was successfully employed to identify DSS1/SHFM1, the RNA binding protein hnRNP A2/B1 and a 3′ UTR as enhancers of editing. By varying intracellular DSS1/SHFM1 levels, we can modulate A to I editing by up to 30%. Proteomic analysis indicates an interaction of DSS1/SHFM1 and hnRNP A2/B1 suggesting that both factors may act by altering the cellular RNP landscape. An extension of this screen to cDNAs from different tissues or developmental stages may prove useful for the identification of additional enhancers of RNA-editing.
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Affiliation(s)
- Wojciech Garncarz
- Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
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Tariq A, Garncarz W, Handl C, Balik A, Pusch O, Jantsch MF. RNA-interacting proteins act as site-specific repressors of ADAR2-mediated RNA editing and fluctuate upon neuronal stimulation. Nucleic Acids Res 2012; 41:2581-93. [PMID: 23275536 PMCID: PMC3575830 DOI: 10.1093/nar/gks1353] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
RNA editing by adenosine deaminases that act on RNA (ADARs) diversifies the transcriptome by changing adenosines to inosines. In mammals, editing levels vary in different tissues, during development, and also in pathogenic conditions. From a screen for repressors of editing we have isolated three proteins that repress ADAR2-mediated RNA editing. The three proteins RPS14, SFRS9 and DDX15 interact with RNA. Overexpression or depletion of these proteins can decrease or increase editing levels by 15%, thus allowing a modulation of RNA editing up to 30%. Interestingly, the three proteins alter RNA editing in a substrate-specific manner that correlates with their RNA binding preferences. In mammalian cells, SFRS9 significantly affects editing of the two substrates CFLAR and cyFIP2, while the ribosomal protein RPS14 mostly inhibits editing of cyFIP2 messenger RNA. The helicase DDX15, in turn, has a strong effect on editing in Caenorhabditis elegans. Expression of the three factors decreases during mouse brain development. Moreover, expression levels of SFRS9 and DDX15 respond strongly to neuronal stimulation or repression, showing an inverse correlation with editing levels. Colocalization and immunoprecipitation studies demonstrate a direct interaction of SFRS9 and RPS14 with ADAR2, while DDX15 associates with other helicases and splicing factors. Our data show that different editing sites can be specifically altered in their editing pattern by changing the local RNP landscape.
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Affiliation(s)
- Aamira Tariq
- Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, Dr. Bohr Gasse 1, A-1030 Vienna, Austria
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Abstract
Adenosine to inosine (A-to-I) RNA editing is a post-transcriptional process by which adenosines are selectively converted to inosines in double-stranded RNA (dsRNA) substrates. A highly conserved group of enzymes, the adenosine deaminase acting on RNA (ADAR) family, mediates this reaction. All ADARs share a common domain architecture consisting of a variable number of amino-terminal dsRNA binding domains (dsRBDs) and a carboxy-terminal catalytic deaminase domain. ADAR family members are highly expressed in the metazoan nervous system, where these enzymes predominantly localize to the neuronal nucleus. Once in the nucleus, ADARs participate in the modification of specific adenosines in pre-mRNAs of proteins involved in electrical and chemical neurotransmission, including pre-synaptic release machineries, and voltage- and ligand-gated ion channels. Most RNA editing sites in these nervous system targets result in non-synonymous codon changes in functionally important, usually conserved, residues and RNA editing deficiencies in various model organisms bear out a crucial role for ADARs in nervous system function. Mutation or deletion of ADAR genes results in striking phenotypes, including seizure episodes, extreme uncoordination, and neurodegeneration. Not only does the process of RNA editing alter important nervous system peptides, but ADARs also regulate gene expression through modification of dsRNA substrates that enter the RNA interference (RNAi) pathway and may then act at the chromatin level. Here, we present a review on the current knowledge regarding the ADAR protein family, including evolutionary history, key structural features, localization, function and mechanism.
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