1
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Morais P, Zhang R, Yu YT. Therapeutic Nonsense Suppression Modalities: From Small Molecules to Nucleic Acid-Based Approaches. Biomedicines 2024; 12:1284. [PMID: 38927491 PMCID: PMC11201248 DOI: 10.3390/biomedicines12061284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Revised: 05/29/2024] [Accepted: 06/07/2024] [Indexed: 06/28/2024] Open
Abstract
Nonsense mutations are genetic mutations that create premature termination codons (PTCs), leading to truncated, defective proteins in diseases such as cystic fibrosis, neurofibromatosis type 1, Dravet syndrome, Hurler syndrome, Beta thalassemia, inherited bone marrow failure syndromes, Duchenne muscular dystrophy, and even cancer. These mutations can also trigger a cellular surveillance mechanism known as nonsense-mediated mRNA decay (NMD) that degrades the PTC-containing mRNA. The activation of NMD can attenuate the consequences of truncated, defective, and potentially toxic proteins in the cell. Since approximately 20% of all single-point mutations are disease-causing nonsense mutations, it is not surprising that this field has received significant attention, resulting in a remarkable advancement in recent years. In fact, since our last review on this topic, new examples of nonsense suppression approaches have been reported, namely new ways of promoting the translational readthrough of PTCs or inhibiting the NMD pathway. With this review, we update the state-of-the-art technologies in nonsense suppression, focusing on novel modalities with therapeutic potential, such as small molecules (readthrough agents, NMD inhibitors, and molecular glue degraders); antisense oligonucleotides; tRNA suppressors; ADAR-mediated RNA editing; targeted pseudouridylation; and gene/base editing. While these various modalities have significantly advanced in their development stage since our last review, each has advantages (e.g., ease of delivery and specificity) and disadvantages (manufacturing complexity and off-target effect potential), which we discuss here.
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Affiliation(s)
- Pedro Morais
- Drug Metabolism and Pharmacokinetics, Research and Development, Bayer Pharmaceuticals, 42113 Wuppertal, Germany
| | - Rui Zhang
- Center for RNA Biology, Department of Biochemistry and Biophysics, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA;
| | - Yi-Tao Yu
- Center for RNA Biology, Department of Biochemistry and Biophysics, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA;
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2
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Ashley CN, Broni E, Miller WA. ADAR Family Proteins: A Structural Review. Curr Issues Mol Biol 2024; 46:3919-3945. [PMID: 38785511 PMCID: PMC11120146 DOI: 10.3390/cimb46050243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 04/22/2024] [Accepted: 04/23/2024] [Indexed: 05/25/2024] Open
Abstract
This review aims to highlight the structures of ADAR proteins that have been crucial in the discernment of their functions and are relevant to future therapeutic development. ADAR proteins can correct or diversify genetic information, underscoring their pivotal contribution to protein diversity and the sophistication of neuronal networks. ADAR proteins have numerous functions in RNA editing independent roles and through the mechanisms of A-I RNA editing that continue to be revealed. Provided is a detailed examination of the ADAR family members-ADAR1, ADAR2, and ADAR3-each characterized by distinct isoforms that offer both structural diversity and functional variability, significantly affecting RNA editing mechanisms and exhibiting tissue-specific regulatory patterns, highlighting their shared features, such as double-stranded RNA binding domains (dsRBD) and a catalytic deaminase domain (CDD). Moreover, it explores ADARs' extensive roles in immunity, RNA interference, and disease modulation, demonstrating their ambivalent nature in both the advancement and inhibition of diseases. Through this comprehensive analysis, the review seeks to underline the potential of targeting ADAR proteins in therapeutic strategies, urging continued investigation into their biological mechanisms and health implications.
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Affiliation(s)
- Carolyn N. Ashley
- Department of Medicine, Loyola University Medical Center, Loyola University Chicago, Maywood, IL 60153, USA; (C.N.A.); (E.B.)
| | - Emmanuel Broni
- Department of Medicine, Loyola University Medical Center, Loyola University Chicago, Maywood, IL 60153, USA; (C.N.A.); (E.B.)
| | - Whelton A. Miller
- Department of Medicine, Loyola University Medical Center, Loyola University Chicago, Maywood, IL 60153, USA; (C.N.A.); (E.B.)
- Department of Molecular Pharmacology & Neuroscience, Loyola University Medical Center, Loyola University Chicago, Maywood, IL 60153, USA
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3
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Xu F, Zheng C, Xu W, Zhang S, Liu S, Chen X, Yao K. Breaking genetic shackles: The advance of base editing in genetic disorder treatment. Front Pharmacol 2024; 15:1364135. [PMID: 38510648 PMCID: PMC10953296 DOI: 10.3389/fphar.2024.1364135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2024] [Accepted: 02/26/2024] [Indexed: 03/22/2024] Open
Abstract
The rapid evolution of gene editing technology has markedly improved the outlook for treating genetic diseases. Base editing, recognized as an exceptionally precise genetic modification tool, is emerging as a focus in the realm of genetic disease therapy. We provide a comprehensive overview of the fundamental principles and delivery methods of cytosine base editors (CBE), adenine base editors (ABE), and RNA base editors, with a particular focus on their applications and recent research advances in the treatment of genetic diseases. We have also explored the potential challenges faced by base editing technology in treatment, including aspects such as targeting specificity, safety, and efficacy, and have enumerated a series of possible solutions to propel the clinical translation of base editing technology. In conclusion, this article not only underscores the present state of base editing technology but also envisions its tremendous potential in the future, providing a novel perspective on the treatment of genetic diseases. It underscores the vast potential of base editing technology in the realm of genetic medicine, providing support for the progression of gene medicine and the development of innovative approaches to genetic disease therapy.
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Affiliation(s)
- Fang Xu
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, China
| | - Caiyan Zheng
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, China
| | - Weihui Xu
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, China
| | - Shiyao Zhang
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, China
| | - Shanshan Liu
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, China
| | - Xiaopeng Chen
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, China
| | - Kai Yao
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, China
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4
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Song J, Luo N, Dong L, Peng J, Yi C. RNA base editors: The emerging approach of RNA therapeutics. WILEY INTERDISCIPLINARY REVIEWS. RNA 2024; 15:e1844. [PMID: 38576085 DOI: 10.1002/wrna.1844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 03/12/2024] [Accepted: 03/18/2024] [Indexed: 04/06/2024]
Abstract
RNA-based therapeutics offer a flexible and reversible approach for treating genetic disorders, such as antisense oligonucleotides, RNA interference, aptamers, mRNA vaccines, and RNA editing. In recent years, significant advancements have been made in RNA base editing to correct disease-relevant point mutations. These achievements have significantly influenced the fields of biotechnology, biomedical research and therapeutics development. In this article, we provide a comprehensive overview of the design and performance of contemporary RNA base editors, including A-to-I, C-to-U, A-to-m6A, and U-to-Ψ. We compare recent innovative developments and highlight their applications in disease-relevant contexts. Lastly, we discuss the limitations and future prospects of utilizing RNA base editing for therapeutic purposes. This article is categorized under: RNA Processing > RNA Editing and Modification RNA in Disease and Development > RNA in Development.
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Affiliation(s)
- Jinghui Song
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Nan Luo
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Liting Dong
- 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
| | - Jinying Peng
- 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 and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
- Beijing Advanced Center of RNA Biology (BEACON), Peking University, Beijing, China
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5
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Song J, Zhuang Y, Yi C. Programmable RNA base editing via targeted modifications. Nat Chem Biol 2024; 20:277-290. [PMID: 38418907 DOI: 10.1038/s41589-023-01531-y] [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: 05/29/2023] [Accepted: 12/18/2023] [Indexed: 03/02/2024]
Abstract
Clustered regularly interspaced short palindromic repeats (CRISPR)-based genome editors are powerful tools in biology and hold great promise for the treatment of human diseases. Advanced DNA base editing tools, such as cytosine base editor and adenine base editor, have been developed to correct permanent mistakes in genetic material. However, undesired off-target edits would also be permanent, which poses a considerable risk for therapeutics. Alternatively, base editing at the RNA level is capable of correcting disease-causing mutations but does not lead to lasting genotoxic effects. RNA base editors offer temporary and reversible therapies and have been catching on in recent years. Here, we summarize some emerging RNA editors based on A-to-inosine, C-to-U and U-to-pseudouridine changes. We review the programmable RNA-targeting systems as well as modification enzyme-based effector proteins and highlight recent technological breakthroughs. Finally, we compare editing tools, discuss limitations and opportunities, and provide insights for the future directions of RNA base editing.
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Affiliation(s)
- Jinghui Song
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, People's Republic of China
| | - Yuan Zhuang
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, People's Republic of China
| | - Chengqi Yi
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, People's Republic of China.
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, People's Republic of China.
- Department of Chemical Biology and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing, People's Republic of China.
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6
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Liu S, Liu H, Wang X, Shi L. The immune system of prokaryotes: potential applications and implications for gene editing. Biotechnol J 2024; 19:e2300352. [PMID: 38403433 DOI: 10.1002/biot.202300352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 11/30/2023] [Accepted: 12/28/2023] [Indexed: 02/27/2024]
Abstract
Gene therapy has revolutionized the treatment of genetic diseases. Spearheading this revolution are sophisticated genome editing methods such as TALENs, ZFNs, and CRISPR-Cas, which trace their origins back to prokaryotic immune systems. Prokaryotes have developed various antiviral defense systems to combat viral attacks and the invasion of genetic elements. The comprehension of these defense mechanisms has paved the way for the development of indispensable tools in molecular biology. Among them, restriction endonuclease originates from the innate immune system of bacteria. The CRISPR-Cas system, a widely applied genome editing technology, is derived from the prokaryotic adaptive immune system. Single-base editing is a precise editing tool based on CRISPR-Cas system that involves deamination of target base. It is worth noting that prokaryotes possess deamination enzymes as part of their defense arsenal over foreign genetic material. Furthermore, prokaryotic Argonauts (pAgo) proteins, also function in anti-phage defense, play an important role in complementing the CRISPR-Cas system by addressing certain limitations it may have. Recent studies have also shed light on the significance of Retron, a reverse transcription transposon previously showed potential in genome editing, has also come to light in the realm of prokaryotic immunity. These noteworthy findings highlight the importance of studying prokaryotic immune system for advancing genome editing techniques. Here, both the origin of prokaryotic immunity underlying aforementioned genome editing tools, and potential applications of deaminase, pAgo protein and reverse transcriptase in genome editing among prokaryotes were introduced, thus emphasizing the fundamental mechanism and significance of prokaryotic immunity.
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Affiliation(s)
- Siyang Liu
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Hongling Liu
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Xue Wang
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Lei Shi
- School of Life Sciences, Chongqing University, Chongqing, China
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7
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Chen JL, Leeder WM, Morais P, Adachi H, Yu YT. Pseudouridylation-mediated gene expression modulation. Biochem J 2024; 481:1-16. [PMID: 38174858 DOI: 10.1042/bcj20230096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Revised: 12/13/2023] [Accepted: 12/19/2023] [Indexed: 01/05/2024]
Abstract
RNA-guided pseudouridylation, a widespread post-transcriptional RNA modification, has recently gained recognition for its role in cellular processes such as pre-mRNA splicing and the modulation of premature termination codon (PTC) readthrough. This review provides insights into its mechanisms, functions, and potential therapeutic applications. It examines the mechanisms governing RNA-guided pseudouridylation, emphasizing the roles of guide RNAs and pseudouridine synthases in catalyzing uridine-to-pseudouridine conversion. A key focus is the impact of RNA-guided pseudouridylation of U2 small nuclear RNA on pre-mRNA splicing, encompassing its influence on branch site recognition and spliceosome assembly. Additionally, the review discusses the emerging role of RNA-guided pseudouridylation in regulating PTC readthrough, impacting translation termination and genetic disorders. Finally, it explores the therapeutic potential of pseudouridine modifications, offering insights into potential treatments for genetic diseases and cancer and the development of mRNA vaccine.
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Affiliation(s)
- Jonathan L Chen
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester Medical Center, Rochester, NY, U.S.A
| | | | | | - Hironori Adachi
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester Medical Center, Rochester, NY, U.S.A
| | - Yi-Tao Yu
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester Medical Center, Rochester, NY, U.S.A
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8
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Pfeiffer LS, Stafforst T. Precision RNA base editing with engineered and endogenous effectors. Nat Biotechnol 2023; 41:1526-1542. [PMID: 37735261 DOI: 10.1038/s41587-023-01927-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 07/26/2023] [Indexed: 09/23/2023]
Abstract
RNA base editing refers to the rewriting of genetic information within an intact RNA molecule and serves various functions, such as evasion of the endogenous immune system and regulation of protein function. To achieve this, certain enzymes have been discovered in human cells that catalyze the conversion of one nucleobase into another. This natural process could be exploited to manipulate and recode any base in a target transcript. In contrast to DNA base editing, analogous changes introduced in RNA are not permanent or inheritable but rather allow reversible and doseable effects that appeal to various therapeutic applications. The current practice of RNA base editing involves the deamination of adenosines and cytidines, which are converted to inosines and uridines, respectively. In this Review, we summarize current site-directed RNA base-editing strategies and highlight recent achievements to improve editing efficiency, precision, codon-targeting scope and in vivo delivery into disease-relevant tissues. Besides engineered editing effectors, we focus on strategies to harness endogenous adenosine deaminases acting on RNA (ADAR) enzymes and discuss limitations and future perspectives to apply the tools in basic research and as a therapeutic modality. We expect the field to realize the first RNA base-editing drug soon, likely on a well-defined genetic disease. However, the long-term challenge will be to carve out the sweet spot of the technology where its unique ability is exploited to modulate signaling cues, metabolism or other clinically relevant processes in a safe and doseable manner.
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Affiliation(s)
- Laura S Pfeiffer
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Thorsten Stafforst
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany.
- Gene and RNA Therapy Center, Faculty of Medicine, University of Tübingen, Tübingen, Germany.
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9
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Azad MTA, Qulsum U, Tsukahara T. Examination of Factors Affecting Site-Directed RNA Editing by the MS2-ADAR1 Deaminase System. Genes (Basel) 2023; 14:1584. [PMID: 37628635 PMCID: PMC10454654 DOI: 10.3390/genes14081584] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 08/02/2023] [Accepted: 08/03/2023] [Indexed: 08/27/2023] Open
Abstract
Adenosine deaminases acting on RNA (ADARs) have double-stranded RNA binding domains and a deaminase domain (DD). We used the MS2 system and specific guide RNAs to direct ADAR1-DD to target adenosines in the mRNA encoding-enhanced green fluorescence protein. Using this system in transfected HEK-293 cells, we evaluated the effects of changing the length and position of the guide RNA on the efficiency of conversion of amber (TAG) and ochre (TAA) stop codons to tryptophan (TGG) in the target. Guide RNAs of 19, 21 and 23 nt were positioned upstream and downstream of the MS2-RNA, providing a total of six guide RNAs. The upstream guide RNAs were more functionally effective than the downstream guide RNAs, with the following hierarchy of efficiency: 21 nt > 23 nt > 19 nt. The highest editing efficiency was 16.6%. Off-target editing was not detected in the guide RNA complementary region but was detected 50 nt downstream of the target. The editing efficiency was proportional to the amount of transfected deaminase but inversely proportional to the amount of the transfected guide RNA. Our results suggest that specific RNA editing requires precise optimization of the ratio of enzyme, guide RNA, and target RNA.
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Affiliation(s)
- Md Thoufic Anam Azad
- Area of Bioscience, Biotechnology and Biomedical Engineering Research Area, Japan Advanced Institute of Science and Technology (JAIST), 1-1 Asahidai, Nomi City 923-1292, Ishikawa, Japan; (M.T.A.A.)
- Department of Veterinary and Animal Sciences, University of Rajshahi, Rajshahi 6205, Bangladesh
| | - Umme Qulsum
- Area of Bioscience, Biotechnology and Biomedical Engineering Research Area, Japan Advanced Institute of Science and Technology (JAIST), 1-1 Asahidai, Nomi City 923-1292, Ishikawa, Japan; (M.T.A.A.)
- Department of Botany, Faculty of Biological Sciences, University of Rajshahi, Rajshahi 6205, Bangladesh
| | - Toshifumi Tsukahara
- Area of Bioscience, Biotechnology and Biomedical Engineering Research Area, Japan Advanced Institute of Science and Technology (JAIST), 1-1 Asahidai, Nomi City 923-1292, Ishikawa, Japan; (M.T.A.A.)
- GeCoRT Co., Ltd., 2-11-2 Takashima, Nishi-ku, Yokohama 220-0011, Kanagawa, Japan
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10
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Booth BJ, Nourreddine S, Katrekar D, Savva Y, Bose D, Long TJ, Huss DJ, Mali P. RNA editing: Expanding the potential of RNA therapeutics. Mol Ther 2023; 31:1533-1549. [PMID: 36620962 PMCID: PMC9824937 DOI: 10.1016/j.ymthe.2023.01.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 12/06/2022] [Accepted: 01/04/2023] [Indexed: 01/09/2023] Open
Abstract
RNA therapeutics have had a tremendous impact on medicine, recently exemplified by the rapid development and deployment of mRNA vaccines to combat the COVID-19 pandemic. In addition, RNA-targeting drugs have been developed for diseases with significant unmet medical needs through selective mRNA knockdown or modulation of pre-mRNA splicing. Recently, RNA editing, particularly antisense RNA-guided adenosine deaminase acting on RNA (ADAR)-based programmable A-to-I editing, has emerged as a powerful tool to manipulate RNA to enable correction of disease-causing mutations and modulate gene expression and protein function. Beyond correcting pathogenic mutations, the technology is particularly well suited for therapeutic applications that require a transient pharmacodynamic effect, such as the treatment of acute pain, obesity, viral infection, and inflammation, where it would be undesirable to introduce permanent alterations to the genome. Furthermore, transient modulation of protein function, such as altering the active sites of enzymes or the interface of protein-protein interactions, opens the door to therapeutic avenues ranging from regenerative medicine to oncology. These emerging RNA-editing-based toolsets are poised to broadly impact biotechnology and therapeutic applications. Here, we review the emerging field of therapeutic RNA editing, highlight recent laboratory advancements, and discuss the key challenges on the path to clinical development.
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Affiliation(s)
| | - Sami Nourreddine
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | | | | | | | | | | | - Prashant Mali
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA.
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11
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Zhang Y, Feng D, Mu G, Wang Q, Wang J, Luo Y, Tang X. Light-triggered site-directed RNA editing by endogenous ADAR1 with photolabile guide RNA. Cell Chem Biol 2023:S2451-9456(23)00149-6. [PMID: 37295425 DOI: 10.1016/j.chembiol.2023.05.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 03/21/2023] [Accepted: 05/18/2023] [Indexed: 06/12/2023]
Abstract
RNA A-to-I editing is a post-transcriptional modification pervasively occurring in cells. Artificial intervention of A-to-I editing at specific sites of RNA could also be achieved with guide RNA and exogenous ADAR enzymes. In contrast to previous fused SNAP-ADAR enzymes for light-driven RNA A-to-I editing, we developed photo-caged antisense guide RNA oligonucleotides with simple 3'-terminal cholesterol modification, and successfully achieved light-triggered site-specific RNA A-to-I editing for the first time utilizing endogenous ADAR enzymes. Our caged A-to-I editing system effectively implemented light-dependent point mutation of mRNA transcripts of both exogenous and endogenous genes in living cells and 3D tumorspheres, as well as spatial regulation of EGFP expression, which provides a new approach for precise manipulation of RNA editing.
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Affiliation(s)
- Yu Zhang
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Di Feng
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Guanqun Mu
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Qian Wang
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Jing Wang
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Yun Luo
- Shanghai Primerna Biotechnology Co. Ltd, Shanghai 201600, China
| | - Xinjing Tang
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China; State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing 210023, Jiangsu, China.
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12
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Liang Y, Chen F, Wang K, Lai L. Base editors: development and applications in biomedicine. Front Med 2023; 17:359-387. [PMID: 37434066 DOI: 10.1007/s11684-023-1013-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 05/19/2023] [Indexed: 07/13/2023]
Abstract
Base editor (BE) is a gene-editing tool developed by combining the CRISPR/Cas system with an individual deaminase, enabling precise single-base substitution in DNA or RNA without generating a DNA double-strand break (DSB) or requiring donor DNA templates in living cells. Base editors offer more precise and secure genome-editing effects than other conventional artificial nuclease systems, such as CRISPR/Cas9, as the DSB induced by Cas9 will cause severe damage to the genome. Thus, base editors have important applications in the field of biomedicine, including gene function investigation, directed protein evolution, genetic lineage tracing, disease modeling, and gene therapy. Since the development of the two main base editors, cytosine base editors (CBEs) and adenine base editors (ABEs), scientists have developed more than 100 optimized base editors with improved editing efficiency, precision, specificity, targeting scope, and capacity to be delivered in vivo, greatly enhancing their application potential in biomedicine. Here, we review the recent development of base editors, summarize their applications in the biomedical field, and discuss future perspectives and challenges for therapeutic applications.
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Affiliation(s)
- Yanhui Liang
- China-New Zealand Joint Laboratory on Biomedicine and Health, CAS Key Laboratory of Regenerative Biology, Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, Centre for Regenerative Medicine and Health, Hong Kong Institute of Science and Innovation, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, 510530, China
- Research Unit of Generation of Large Animal Disease Models, Chinese Academy of Medical Sciences (2019RU015), Guangzhou, 510530, China
- Sanya Institute of Swine Resource, Hainan Provincial Research Centre of Laboratory Animals, Sanya, 572000, China
| | - Fangbing Chen
- China-New Zealand Joint Laboratory on Biomedicine and Health, CAS Key Laboratory of Regenerative Biology, Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, Centre for Regenerative Medicine and Health, Hong Kong Institute of Science and Innovation, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, 510530, China
- Research Unit of Generation of Large Animal Disease Models, Chinese Academy of Medical Sciences (2019RU015), Guangzhou, 510530, China
- Sanya Institute of Swine Resource, Hainan Provincial Research Centre of Laboratory Animals, Sanya, 572000, China
- Guangdong Provincial Key Laboratory of Large Animal Models for Biomedicine, Wuyi University, Jiangmen, 529020, China
| | - Kepin Wang
- China-New Zealand Joint Laboratory on Biomedicine and Health, CAS Key Laboratory of Regenerative Biology, Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, Centre for Regenerative Medicine and Health, Hong Kong Institute of Science and Innovation, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, 510530, China
- Research Unit of Generation of Large Animal Disease Models, Chinese Academy of Medical Sciences (2019RU015), Guangzhou, 510530, China
- Sanya Institute of Swine Resource, Hainan Provincial Research Centre of Laboratory Animals, Sanya, 572000, China
- Guangdong Provincial Key Laboratory of Large Animal Models for Biomedicine, Wuyi University, Jiangmen, 529020, China
| | - Liangxue Lai
- China-New Zealand Joint Laboratory on Biomedicine and Health, CAS Key Laboratory of Regenerative Biology, Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, Centre for Regenerative Medicine and Health, Hong Kong Institute of Science and Innovation, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, 510530, China.
- Research Unit of Generation of Large Animal Disease Models, Chinese Academy of Medical Sciences (2019RU015), Guangzhou, 510530, China.
- Sanya Institute of Swine Resource, Hainan Provincial Research Centre of Laboratory Animals, Sanya, 572000, China.
- Guangdong Provincial Key Laboratory of Large Animal Models for Biomedicine, Wuyi University, Jiangmen, 529020, China.
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13
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Bellingrath JS, McClements ME, Fischer MD, MacLaren RE. Programmable RNA editing with endogenous ADAR enzymes - a feasible option for the treatment of inherited retinal disease? Front Mol Neurosci 2023; 16:1092913. [PMID: 37293541 PMCID: PMC10244592 DOI: 10.3389/fnmol.2023.1092913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 04/27/2023] [Indexed: 06/10/2023] Open
Abstract
RNA editing holds great promise for the therapeutic correction of pathogenic, single nucleotide variants (SNV) in the human transcriptome since it does not risk creating permanent off-targets edits in the genome and has the potential for innovative delivery options. Adenine deaminases acting on RNA (ADAR) enzymes catalyse the most widespread form of posttranscriptional RNA editing in humans and their ability to hydrolytically deaminate adenosine to inosine in double stranded RNA (dsRNA) has been harnessed to change pathogenic single nucleotide variants (SNVs) in the human genome on a transcriptional level. Until now, the most promising target editing rates have been achieved by exogenous delivery of the catalytically active ADAR deaminase domain (ADARDD) fused to an RNA binding protein. While it has been shown that endogenous ADARs can be recruited to a defined target site with the sole help of an ADAR-recruiting guide RNA, thus freeing up packaging space, decreasing the chance of an immune response against a foreign protein, and decreasing transcriptome-wide off-target effects, this approach has been limited by a low editing efficiency. Through the recent development of novel circular ADAR-recruiting guide RNAs as well as the optimisation of ADAR-recruiting antisense oligonucleotides, RNA editing with endogenous ADAR is now showing promising target editing efficiency in vitro and in vivo. A target editing efficiency comparable to RNA editing with exogenous ADAR was shown both in wild-type and disease mouse models as well as in wild-type non-human primates (NHP) immediately following and up to 6 weeks after application. With these encouraging results, RNA editing with endogenous ADAR has the potential to present an attractive option for the treatment of inherited retinal diseases (IRDs), a field where gene replacement therapy has been established as safe and efficacious, but where an unmet need still exists for genes that exceed the packaging capacity of an adeno associated virus (AAV) or are expressed in more than one retinal isoform. This review aims to give an overview of the recent developments in the field of RNA editing with endogenous ADAR and assess its applicability for the field of treatment of IRD.
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Affiliation(s)
- Julia-Sophia Bellingrath
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Michelle E. McClements
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - M. Dominik Fischer
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- Oxford Eye Hospital, Oxford University Hospitals NHS Trust, Oxford, United Kingdom
| | - Robert E. MacLaren
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- Oxford Eye Hospital, Oxford University Hospitals NHS Trust, Oxford, United Kingdom
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14
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Bhokisham N, Laudermilch E, Traeger LL, Bonilla TD, Ruiz-Estevez M, Becker JR. CRISPR-Cas System: The Current and Emerging Translational Landscape. Cells 2023; 12:cells12081103. [PMID: 37190012 DOI: 10.3390/cells12081103] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Revised: 04/03/2023] [Accepted: 04/04/2023] [Indexed: 05/17/2023] Open
Abstract
CRISPR-Cas technology has rapidly changed life science research and human medicine. The ability to add, remove, or edit human DNA sequences has transformative potential for treating congenital and acquired human diseases. The timely maturation of the cell and gene therapy ecosystem and its seamless integration with CRISPR-Cas technologies has enabled the development of therapies that could potentially cure not only monogenic diseases such as sickle cell anemia and muscular dystrophy, but also complex heterogenous diseases such as cancer and diabetes. Here, we review the current landscape of clinical trials involving the use of various CRISPR-Cas systems as therapeutics for human diseases, discuss challenges, and explore new CRISPR-Cas-based tools such as base editing, prime editing, CRISPR-based transcriptional regulation, CRISPR-based epigenome editing, and RNA editing, each promising new functionality and broadening therapeutic potential. Finally, we discuss how the CRISPR-Cas system is being used to understand the biology of human diseases through the generation of large animal disease models used for preclinical testing of emerging therapeutics.
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Affiliation(s)
| | - Ethan Laudermilch
- Corporate Research Material Labs, 3M Center, 3M Company, Maplewood, MN 55144, USA
| | - Lindsay L Traeger
- Corporate Research Material Labs, 3M Center, 3M Company, Maplewood, MN 55144, USA
| | - Tonya D Bonilla
- Corporate Research Material Labs, 3M Center, 3M Company, Maplewood, MN 55144, USA
| | | | - Jordan R Becker
- Corporate Research Material Labs, 3M Center, 3M Company, Maplewood, MN 55144, USA
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15
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Diaz Quiroz JF, Siskel LD, Rosenthal JJC. Site-directed A → I RNA editing as a therapeutic tool: moving beyond genetic mutations. RNA (NEW YORK, N.Y.) 2023; 29:498-505. [PMID: 36669890 PMCID: PMC10019371 DOI: 10.1261/rna.079518.122] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Adenosine deamination by the ADAR family of enzymes is a natural process that edits genetic information as it passes through messenger RNA. Adenosine is converted to inosine in mRNAs, and this base is interpreted as guanosine during translation. Realizing the potential of this activity for therapeutics, a number of researchers have developed systems that redirect ADAR activity to new targets, ones that are not normally edited. These site-directed RNA editing (SDRE) systems can be broadly classified into two categories: ones that deliver an antisense RNA oligonucleotide to bind opposite a target adenosine, creating an editable structure that endogenously expressed ADARs recognize, and ones that tether the catalytic domain of recombinant ADAR to an antisense RNA oligonucleotide that serves as a targeting mechanism, much like with CRISPR-Cas or RNAi. To date, SDRE has been used mostly to try and correct genetic mutations. Here we argue that these applications are not ideal SDRE, mostly because RNA edits are transient and genetic mutations are not. Instead, we suggest that SDRE could be used to tune cell physiology to achieve temporary outcomes that are therapeutically advantageous, particularly in the nervous system. These include manipulating excitability in nociceptive neural circuits, abolishing specific phosphorylation events to reduce protein aggregation related to neurodegeneration or reduce the glial scarring that inhibits nerve regeneration, or enhancing G protein-coupled receptor signaling to increase nerve proliferation for the treatment of sensory disorders like blindness and deafness.
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Affiliation(s)
- Juan F Diaz Quiroz
- Eugene Bell Center, The Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA
| | - Louise D Siskel
- Eugene Bell Center, The Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA
| | - Joshua J C Rosenthal
- Eugene Bell Center, The Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA
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16
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Lei Z, Meng H, Zhuang Y, Zhu Q, Yi C. Chemical and Biological Approaches to Interrogate off-Target Effects of Genome Editing Tools. ACS Chem Biol 2023; 18:205-217. [PMID: 36731114 DOI: 10.1021/acschembio.2c00836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Various genome editing tools have been developed for programmable genome manipulation at specified genomic loci. However, it is crucial to comprehensively interrogate the off-target effect induced by these genome editing tools, especially when apply them onto the therapeutic applications. Here, we outlined the off-target effect that has been observed for various genome editing tools. We also reviewed detection methods to determine or evaluate the off-target editing, and we have discussed their advantages and limitations. Additionally, we have summarized current RNA editing tools for RNA therapy and medicine that may serve as alternative approaches for genome editing tools in both research and clinical applications.
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Affiliation(s)
- Zhixin Lei
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing100871, China.,Academy for Advanced Interdisciplinary Studies, Peking University, Beijing100871, China
| | - Haowei Meng
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing100871, China
| | - Yuan Zhuang
- Peking University-Tsinghua University-National Institute of Biological Sciences Joint Graduate Program, School of Life Sciences, Peking University, Beijing100871, China
| | - Qingguo Zhu
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing100871, China.,Academy for Advanced Interdisciplinary Studies, Peking University, Beijing100871, China
| | - Chengqi Yi
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing100871, China.,State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing100871, China.,Department of Chemical Biology and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing100871, China.,Peking University Genome Editing Research Center, Peking University, Beijing100871, China
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17
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Li M, Yan C, Jiao Y, Xu Y, Bai C, Miao R, Jiang J, Liu J. Site-directed RNA editing by harnessing ADARs: advances and challenges. Funct Integr Genomics 2022; 22:1089-1103. [DOI: 10.1007/s10142-022-00910-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 10/12/2022] [Accepted: 10/17/2022] [Indexed: 11/04/2022]
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18
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Xiang Y, Katrekar D, Mali P. Methods for recruiting endogenous and exogenous ADAR enzymes for site-specific RNA editing. Methods 2022; 205:158-166. [PMID: 35779766 DOI: 10.1016/j.ymeth.2022.06.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 06/08/2022] [Accepted: 06/27/2022] [Indexed: 12/01/2022] Open
Abstract
Adenosine deaminases acting on RNA (ADARs) can be repurposed to achieve site-specific A-to-I RNA editing by recruiting them to a target of interest via an ADAR-recruiting guide RNA (adRNA). In this chapter, we present details towards experimental methods to enable this via two orthogonal strategies: one, via recruitment of endogenous ADARs (i.e. ADARs already natively expressed in cells); and two, via recruitment of exogenous ADARs (i.e. ADARs delivered into cells). Towards the former, we describe the use of circular adRNAs to recruit endogenous ADARs to a desired mRNA target. This results in robust, persistent and highly transcript specific editing both in vitro and in vivo. Towards the latter, we describe the use of a split-ADAR2 system, which allows for overexpression of ADAR2 variants that can be utilized to edit adenosines with high specificity, including at challenging to edit adenosines in non-preferred motifs such as those flanked by a 5' guanosine. We anticipate the described methods should facilitate RNA editing applications across research and biotechnology settings.
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Affiliation(s)
- Yichen Xiang
- Department of Bioengineering, University of California San Diego, USA
| | | | - Prashant Mali
- Department of Bioengineering, University of California San Diego, USA.
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19
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Han RC, MacLaren RE. RNA gene editing in the eye and beyond: The neglected tool of the gene editing armatorium? INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2022; 372:175-205. [PMID: 36064264 DOI: 10.1016/bs.ircmb.2022.04.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
RNA editing allows correction of pathological point mutations without permanently altering genomic DNA. Theoretically targetable to any RNA type and site, its flexibility and reversibility makes it a potentially powerful gene editing tool. RNA editing offers a host of potential advantages in specific niches when compared to currently available alternative gene manipulation techniques. Unlike DNA editors, which are currently too large to be delivered in vivo using a viral vector, smaller RNA editors fit easily within the capabilities of an adeno-associated virus (AAV). Unlike gene augmentation, which is limited by gene size and viral packaging constraints, RNA editing may correct transcripts too long to fit within a viral vector. In this article we examine the development of RNA editing and discuss potential applications and pitfalls. We argue that, although in its infancy, an RNA editing approach can offer unique advantages for selected retinal diseases.
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Affiliation(s)
- Ruofan Connie Han
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom.
| | - Robert E MacLaren
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom; Oxford Eye Hospital, John Radcliffe, Oxford, United Kingdom
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20
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Sinnamon JR, Jacobson ME, Yung JF, Fisk JR, Jeng S, McWeeney SK, Parmelee LK, Chan CN, Yee SP, Mandel G. Targeted RNA editing in brainstem alleviates respiratory dysfunction in a mouse model of Rett syndrome. Proc Natl Acad Sci U S A 2022; 119:e2206053119. [PMID: 35939700 PMCID: PMC9388114 DOI: 10.1073/pnas.2206053119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 06/27/2022] [Indexed: 12/26/2022] Open
Abstract
Rett syndrome is a neurological disease due to loss-of-function mutations in the transcription factor, Methyl CpG binding protein 2 (MECP2). Because overexpression of endogenous MECP2 also causes disease, we have exploited a targeted RNA-editing approach to repair patient mutations where levels of MECP2 protein will never exceed endogenous levels. Here, we have constructed adeno-associated viruses coexpressing a bioengineered wild-type ADAR2 catalytic domain (Editasewt) and either Mecp2-targeting or nontargeting gfp RNA guides. The viruses are introduced systemically into male mice containing a guanosine to adenosine mutation that eliminates MeCP2 protein and causes classic Rett syndrome in humans. We find that in the mutant mice injected with the Mecp2-targeting virus, the brainstem exhibits the highest RNA-editing frequency compared to other brain regions. The efficiency is sufficient to rescue MeCP2 expression and function in the brainstem of mice expressing the Mecp2-targeting virus. Correspondingly, we find that abnormal Rett-like respiratory patterns are alleviated, and survival is prolonged, compared to mice injected with the control gfp guide virus. The levels of RNA editing among most brain regions corresponds to the distribution of guide RNA rather than Editasewt. Our results provide evidence that a targeted RNA-editing approach can alleviate a hallmark symptom in a mouse model of human disease.
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Affiliation(s)
- John R. Sinnamon
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239
| | | | - John F. Yung
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239
| | - Jenna R. Fisk
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239
| | - Sophia Jeng
- Knight Cancer Institute, Oregon Health and Science University, Portland, OR 97239
| | - Shannon K. McWeeney
- Knight Cancer Institute, Oregon Health and Science University, Portland, OR 97239
- Division of Bioinformatics and Computational Biology, Oregon Health and Science University, Portland, OR 97239
- Department of Medical Informatics and Clinical Epidemiology, Oregon Health and Science University, Portland, OR 97239
- Oregon Clinical and Translational Research Institute, Oregon Health and Science University, Portland, OR 97239
| | - Lindsay K. Parmelee
- Integrated Pathology Core, Oregon National Primate Research Center, Beaverton, OR 97006
| | - Chi Ngai Chan
- Integrated Pathology Core, Oregon National Primate Research Center, Beaverton, OR 97006
| | - Siu-Pok Yee
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030
| | - Gail Mandel
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239
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21
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Liu X, Zhang Y, Zhou S, Dain L, Mei L, Zhu G. Circular RNA: An emerging frontier in RNA therapeutic targets, RNA therapeutics, and mRNA vaccines. J Control Release 2022; 348:84-94. [PMID: 35649485 PMCID: PMC9644292 DOI: 10.1016/j.jconrel.2022.05.043] [Citation(s) in RCA: 96] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 05/17/2022] [Accepted: 05/25/2022] [Indexed: 12/13/2022]
Abstract
Circular RNAs (circRNA) is a class of natural (biogenic) or synthetic closed RNA without 5' or 3' ends. Meanwhile, their unique covalently-closed structures of circRNA prevent RNA degradation by exonucleases, thereby empowering them with high pharmaceutical stability and biostability relative to current standard-of-care linear mRNA. Natural circRNA can be non-coding RNAs as well as protein-coding RNA, the latter of which was recently discovered. The physiological functions of biogenic circRNAs, which largely remain elusive, include protein and gene sponges, cell activity modulators, and protein translation. The discovery that the circRNA levels can be correlated with some human diseases empowers circRNA with the potential as a novel type of disease biomarkers and a noncanonical class of therapeutic targets. Recently, synthetic circRNA have been engineered to explore their applications as a novel class of mRNA therapeutics and vaccines. In this review, we will discuss the current understanding of the biogenesis and physiological functions of natural circRNAs, the approaches to circRNA synthesis, and current research in the exploration of endogenous circRNAs as novel therapeutic targets and testing circRNAs as an emerging class of RNA therapeutics and vaccines.
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Affiliation(s)
- Xiang Liu
- Department of Pharmaceutics and Center for Pharmaceutical Engineering and Sciences, School of Pharmacy, Institute for Structural Biology and Drug Discovery, The Developmental Therapeutics Program, Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Yu Zhang
- Department of Pharmaceutics and Center for Pharmaceutical Engineering and Sciences, School of Pharmacy, Institute for Structural Biology and Drug Discovery, The Developmental Therapeutics Program, Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Shurong Zhou
- Department of Pharmaceutics and Center for Pharmaceutical Engineering and Sciences, School of Pharmacy, Institute for Structural Biology and Drug Discovery, The Developmental Therapeutics Program, Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Lauren Dain
- Department of Pharmaceutics and Center for Pharmaceutical Engineering and Sciences, School of Pharmacy, Institute for Structural Biology and Drug Discovery, The Developmental Therapeutics Program, Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Lei Mei
- Department of Pharmaceutics and Center for Pharmaceutical Engineering and Sciences, School of Pharmacy, Institute for Structural Biology and Drug Discovery, The Developmental Therapeutics Program, Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Guizhi Zhu
- Department of Pharmaceutics and Center for Pharmaceutical Engineering and Sciences, School of Pharmacy, Institute for Structural Biology and Drug Discovery, The Developmental Therapeutics Program, Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, USA.
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22
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Xiao Q, Xu Z, Xue Y, Xu C, Han L, Liu Y, Wang F, Zhang R, Han S, Wang X, Li GL, Li H, Yang H, Shu Y. Rescue of autosomal dominant hearing loss by in vivo delivery of mini dCas13X-derived RNA base editor. Sci Transl Med 2022; 14:eabn0449. [PMID: 35857824 DOI: 10.1126/scitranslmed.abn0449] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Programmable RNA editing tools enable the reversible correction of mutant transcripts, reducing the potential risk associated with permanent genetic changes associated with the use of DNA editing tools. However, the potential of these RNA tools to treat disease remains unknown. Here, we evaluated RNA correction therapy with Cas13-based RNA base editors in the myosin VI p.C442Y heterozygous mutation (Myo6C442Y/+) mouse model that recapitulated the phenotypes of human dominant-inherited deafness. We first screened several variants of Cas13-based RNA base editors and guide RNAs (gRNAs) targeting Myo6C442Y in cultured cells and found that mini dCas13X.1-based adenosine base editor (mxABE), composed of truncated Cas13X.1 and the RNA editing enzyme adenosine deaminase acting on RNA 2 deaminase domain variant (ADAR2ddE488Q), exhibited both high efficiency of A > G conversion and low frequency of off-target edits. Single adeno-associated virus (AAV)-mediated delivery of mxABE in the cochlea corrected the mutated Myo6C442Y to Myo6WT allele in homozygous Myo6C442Y/C442Y mice and resulted in increased Myo6WT allele in the injected cochlea of Myo6C442Y/+ mice. The treatment rescued auditory function, including auditory brainstem response and distortion product otoacoustic emission up to 3 months after AAV-mxABE-Myo6 injection in Myo6C442Y/+ mice. We also observed increased survival rate of hair cells and decreased degeneration of hair bundle morphology in the treated compared to untreated control ears. These findings provide a proof-of-concept study for RNA editing tools as a therapeutic treatment for various semidominant forms of hearing loss and other diseases.
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Affiliation(s)
- Qingquan Xiao
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Key Laboratory of Primate Neurobiology, CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai Research Center for Brain Science and Brain-Inspired Intelligence, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhijiao Xu
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200031, China
- Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai 200032, China
| | - Yuanyuan Xue
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200031, China
- Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai 200032, China
| | - Chunlong Xu
- Lingang Laboratory, Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai 200032, China
| | - Lei Han
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200031, China
- Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai 200032, China
- Department of Otorhinolaryngology, Second Affiliated Hospital, University of South China, Hengyang 421001, China
| | - Yuanhua Liu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Key Laboratory of Primate Neurobiology, CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai Research Center for Brain Science and Brain-Inspired Intelligence, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Fang Wang
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200031, China
- Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai 200032, China
| | - Runze Zhang
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Key Laboratory of Primate Neurobiology, CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai Research Center for Brain Science and Brain-Inspired Intelligence, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shuang Han
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200031, China
- Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai 200032, China
- Department of Otolaryngology Head and Neck Surgery, Second Hospital of Jilin University, Changchun 130000, China
| | - Xing Wang
- Huigene Therapeutics Inc., Shanghai 201315, China
| | - Geng-Lin Li
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200031, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai 200032, China
| | - Huawei Li
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200031, China
- Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai 200032, China
- Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, China
| | - Hui Yang
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Key Laboratory of Primate Neurobiology, CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai Research Center for Brain Science and Brain-Inspired Intelligence, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Yilai Shu
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200031, China
- Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai 200032, China
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23
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Doherty EE, Beal PA. Oligonucleotide-directed RNA editing in primates. Mol Ther 2022; 30:2117-2119. [PMID: 35460609 PMCID: PMC9171251 DOI: 10.1016/j.ymthe.2022.04.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 04/09/2022] [Indexed: 02/03/2023] Open
Affiliation(s)
- Erin E. Doherty
- Department of Chemistry, University of California, Davis, CA 95616, USA
| | - Peter A. Beal
- Department of Chemistry, University of California, Davis, CA 95616, USA,Corresponding author: Peter A. Beal, PhD, Department of Chemistry, University of California, Davis, CA 95616, USA.
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24
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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:e75555. [PMID: 35044296 PMCID: PMC8809894 DOI: 10.7554/elife.75555] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [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)
- Dhruva Katrekar
- Department of Bioengineering, University of California San DiegoSan DiegoUnited States
| | - Yichen Xiang
- Department of Bioengineering, University of California San DiegoSan DiegoUnited States
| | - Nathan Palmer
- Division of Biological Sciences, University of California San DiegoSan DiegoUnited States
| | - Anushka Saha
- Department of Bioengineering, University of California San DiegoSan DiegoUnited States
| | - Dario Meluzzi
- Department of Bioengineering, University of California San DiegoSan DiegoUnited States
| | - Prashant Mali
- Department of Bioengineering, University of California San DiegoSan DiegoUnited States
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25
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Wang Y, Wang H, Jian Y, Luo Z, Shao H, Zhang W. Strategies for optimization of the CRISPR-based genome editing system for enhanced editing specificity. Hum Gene Ther 2021; 33:358-370. [PMID: 34963339 DOI: 10.1089/hum.2021.283] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The clustered regularly interspaced short palindromic repeats (CRISPR) system is inarguably the most valuable gene editing tool ever discovered. Currently, three classes of CRISPR-based genome editing systems have been developed for gene editing, including CRISPR/Cas nucleases, base editors (BEs) and prime editors (PEs). Ever-evolving CRISPR technology plays an important role in medicine; however, the biggest obstacle to its use in clinical practice is the induction of off-target effects (OTEs) during targeted editing. Therefore, continuous improvement and optimization of the CRISPR system for reduction of OTEs is a major focus in the field of CRISPR research. This review aims to provide a comprehensive guide for optimization of the CRISPR-based genome editing system.
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Affiliation(s)
- Yangmin Wang
- Guangdong Pharmaceutical University, 71237, Guangzhou, Guangdong, China;
| | - Haozheng Wang
- Guangdong Pharmaceutical University, 71237, Guangzhou, Guangdong, China;
| | - Yingzhen Jian
- Guangdong Pharmaceutical University, 71237, Guangzhou, Guangdong, China;
| | - Zhongtao Luo
- Guangdong Pharmaceutical University, 71237, Guangzhou, Guangdong, China;
| | - Hongwei Shao
- Guangdong Pharmaceutical University, 71237, Guangzhou, Guangdong, China;
| | - Wenfeng Zhang
- Guangdong Pharmaceutical University, 71237, School of Biosciences and Biopharmaceutics , 28 E. Rd outside the City of Guangzhou University, Guangzhou, China, 510006;
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26
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Schneider N, Sundaresan Y, Gopalakrishnan P, Beryozkin A, Hanany M, Levanon EY, Banin E, Ben-Aroya S, Sharon D. Inherited retinal diseases: Linking genes, disease-causing variants, and relevant therapeutic modalities. Prog Retin Eye Res 2021; 89:101029. [PMID: 34839010 DOI: 10.1016/j.preteyeres.2021.101029] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 11/11/2021] [Accepted: 11/16/2021] [Indexed: 12/11/2022]
Abstract
Inherited retinal diseases (IRDs) are a clinically complex and heterogenous group of visual impairment phenotypes caused by pathogenic variants in at least 277 nuclear and mitochondrial genes, affecting different retinal regions, and depleting the vision of affected individuals. Genes that cause IRDs when mutated are unique by possessing differing genotype-phenotype correlations, varying inheritance patterns, hypomorphic alleles, and modifier genes thus complicating genetic interpretation. Next-generation sequencing has greatly advanced the identification of novel IRD-related genes and pathogenic variants in the last decade. For this review, we performed an in-depth literature search which allowed for compilation of the Global Retinal Inherited Disease (GRID) dataset containing 4,798 discrete variants and 17,299 alleles published in 31 papers, showing a wide range of frequencies and complexities among the 194 genes reported in GRID, with 65% of pathogenic variants being unique to a single individual. A better understanding of IRD-related gene distribution, gene complexity, and variant types allow for improved genetic testing and therapies. Current genetic therapeutic methods are also quite diverse and rely on variant identification, and range from whole gene replacement to single nucleotide editing at the DNA or RNA levels. IRDs and their suitable therapies thus require a range of effective disease modelling in human cells, granting insight into disease mechanisms and testing of possible treatments. This review summarizes genetic and therapeutic modalities of IRDs, provides new analyses of IRD-related genes (GRID and complexity scores), and provides information to match genetic-based therapies such as gene-specific and variant-specific therapies to the appropriate individuals.
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Affiliation(s)
- Nina Schneider
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel
| | - Yogapriya Sundaresan
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel
| | - Prakadeeswari Gopalakrishnan
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel
| | - Avigail Beryozkin
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel
| | - Mor Hanany
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel
| | - Erez Y Levanon
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, 5290002, Israel
| | - Eyal Banin
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel
| | - Shay Ben-Aroya
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, 5290002, Israel
| | - Dror Sharon
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel.
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27
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Khosravi HM, Jantsch MF. Site-directed RNA editing: recent advances and open challenges. RNA Biol 2021; 18:41-50. [PMID: 34569891 PMCID: PMC8677011 DOI: 10.1080/15476286.2021.1983288] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Revised: 08/25/2021] [Accepted: 09/16/2021] [Indexed: 12/19/2022] Open
Abstract
RNA editing by cytosine and adenosine deaminases changes the identity of the edited bases. While cytosines are converted to uracils, adenines are converted to inosines. If coding regions of mRNAs are affected, the coding potential of the RNA can be changed, depending on the codon affected. The recoding potential of nucleotide deaminases has recently gained attention for their ability to correct genetic mutations by either reverting the mutation itself or by manipulating processing steps such as RNA splicing. In contrast to CRISPR-based DNA-editing approaches, RNA editing events are transient in nature, therefore reducing the risk of long-lasting inadvertent side-effects. Moreover, some RNA-based therapeutics are already FDA approved and their use in targeting multiple cells or organs to restore genetic function has already been shown. In this review, we provide an overview on the current status and technical differences of site-directed RNA-editing approaches. We also discuss advantages and challenges of individual approaches.
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Affiliation(s)
- Hamid Mansouri Khosravi
- Center of Anatomy & Cell Biology Division of Cell & Developmental Biology Medical, Unviersity of Vienna SchwarzspanierstrasseVienna, Austria
| | - Michael F. Jantsch
- Center of Anatomy & Cell Biology Division of Cell & Developmental Biology Medical, Unviersity of Vienna SchwarzspanierstrasseVienna, Austria
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28
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Ojha N, Diaz Quiroz JF, Rosenthal JJC. In vitro and in cellula site-directed RNA editing using the λNDD-BoxB system. Methods Enzymol 2021; 658:335-358. [PMID: 34517953 DOI: 10.1016/bs.mie.2021.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Site-directed RNA editing (SDRE) exploits the enzymatic activity of Adenosine Deaminases Acting on RNAs (ADAR) to program changes in genetic information as it passes through RNA. ADARs convert adenosine (A) to inosine (I) through a hydrolytic deamination and since I can be read as guanosine (G) during translation, this change can regulate gene function and correct G→A genetic mutations. In SDRE, ADARs are redirected to convert user-defined A's to I's. SDRE also has certain advantages over genome editing because the changes in RNA are reversible and thus safer. In addition, ADARs are endogenously expressed in humans and therefore unlikely to provoke immunological complications when administered. Recently, a variety of systems for SDRE have been developed. Some rely on harnessing endogenously expressed ADARs and other deliver engineered versions of ADAR's catalytic domain. All systems are currently under refinement, and there are still challenges associated with raising their efficiency and specificity to levels that are adequate for therapeutics. This chapter provides a detailed protocol for in vitro and in cellula editing assays using the λNDD-BoxB system, one of the first systems developed for SDRE. The λNDD-BoxB system relies on gRNAs that are linked to the catalytic domain of human ADAR2 through a small RNA binding protein-RNA stem/loop interaction. We provide step-by-step protocols for (a) the construction of guide RNAs and editing enzyme plasmids, and (b) their use in vitro and in cellula for editing assays using a fluorescent protein-based reporter system containing a premature termination codon that can be corrected by editing.
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Affiliation(s)
- Namrata Ojha
- The Eugene Bell Center, The Marine Biological Laboratory, Woods Hole, MA, United States
| | | | - Joshua J C Rosenthal
- The Eugene Bell Center, The Marine Biological Laboratory, Woods Hole, MA, United States.
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29
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Bhakta S, Tsukahara T. Artificial RNA Editing with ADAR for Gene Therapy. Curr Gene Ther 2021; 20:44-54. [PMID: 32416688 DOI: 10.2174/1566523220666200516170137] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 04/28/2020] [Accepted: 04/29/2020] [Indexed: 12/14/2022]
Abstract
Editing mutated genes is a potential way for the treatment of genetic diseases. G-to-A mutations are common in mammals and can be treated by adenosine-to-inosine (A-to-I) editing, a type of substitutional RNA editing. The molecular mechanism of A-to-I editing involves the hydrolytic deamination of adenosine to an inosine base; this reaction is mediated by RNA-specific deaminases, adenosine deaminases acting on RNA (ADARs), family protein. Here, we review recent findings regarding the application of ADARs to restoring the genetic code along with different approaches involved in the process of artificial RNA editing by ADAR. We have also addressed comparative studies of various isoforms of ADARs. Therefore, we will try to provide a detailed overview of the artificial RNA editing and the role of ADAR with a focus on the enzymatic site directed A-to-I editing.
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Affiliation(s)
- Sonali Bhakta
- Area of Bioscience and Biotechnology, School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomicity, Ishikawa, 923-1292, Japan
| | - Toshifumi Tsukahara
- Area of Bioscience and Biotechnology, School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomicity, Ishikawa, 923-1292, Japan
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30
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From Antisense RNA to RNA Modification: Therapeutic Potential of RNA-Based Technologies. Biomedicines 2021; 9:biomedicines9050550. [PMID: 34068948 PMCID: PMC8156014 DOI: 10.3390/biomedicines9050550] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Revised: 05/07/2021] [Accepted: 05/10/2021] [Indexed: 02/07/2023] Open
Abstract
Therapeutic oligonucleotides interact with a target RNA via Watson-Crick complementarity, affecting RNA-processing reactions such as mRNA degradation, pre-mRNA splicing, or mRNA translation. Since they were proposed decades ago, several have been approved for clinical use to correct genetic mutations. Three types of mechanisms of action (MoA) have emerged: RNase H-dependent degradation of mRNA directed by short chimeric antisense oligonucleotides (gapmers), correction of splicing defects via splice-modulation oligonucleotides, and interference of gene expression via short interfering RNAs (siRNAs). These antisense-based mechanisms can tackle several genetic disorders in a gene-specific manner, primarily by gene downregulation (gapmers and siRNAs) or splicing defects correction (exon-skipping oligos). Still, the challenge remains for the repair at the single-nucleotide level. The emerging field of epitranscriptomics and RNA modifications shows the enormous possibilities for recoding the transcriptome and repairing genetic mutations with high specificity while harnessing endogenously expressed RNA processing machinery. Some of these techniques have been proposed as alternatives to CRISPR-based technologies, where the exogenous gene-editing machinery needs to be delivered and expressed in the human cells to generate permanent (DNA) changes with unknown consequences. Here, we review the current FDA-approved antisense MoA (emphasizing some enabling technologies that contributed to their success) and three novel modalities based on post-transcriptional RNA modifications with therapeutic potential, including ADAR (Adenosine deaminases acting on RNA)-mediated RNA editing, targeted pseudouridylation, and 2′-O-methylation.
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31
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Doherty EE, Wilcox XE, van Sint Fiet L, Kemmel C, Turunen JJ, Klein B, Tantillo DJ, Fisher AJ, Beal PA. Rational Design of RNA Editing Guide Strands: Cytidine Analogs at the Orphan Position. J Am Chem Soc 2021; 143:6865-6876. [PMID: 33939417 PMCID: PMC8608393 DOI: 10.1021/jacs.0c13319] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Adenosine Deaminases Acting on RNA (ADARs) convert adenosine to inosine in double stranded RNA. Human ADARs can be directed to predetermined target sites in the transcriptome by complementary guide strands, allowing for the correction of disease-causing mutations at the RNA level. Here we use structural information available for ADAR2-RNA complexes to guide the design of nucleoside analogs for the position in the guide strand that contacts a conserved glutamic acid residue in ADARs (E488 in human ADAR2), which flips the adenosine into the ADAR active site for deamination. Mutating this residue to glutamine (E488Q) results in higher activity because of the hydrogen bond donating ability of Q488 to N3 of the orphan cytidine on the guide strand. We describe the evaluation of cytidine analogs for this position that stabilize an activated conformation of the enzyme-RNA complex and increase catalytic rate for deamination by the wild-type enzyme. A new crystal structure of ADAR2 bound to duplex RNA bearing a cytidine analog revealed a close contact between E488, stabilized by an additional hydrogen bond and altered charge distribution when compared to cytidine. In human cells and mouse primary liver fibroblasts, this single nucleotide modification increased directed editing yields when compared to an otherwise identical guide oligonucleotide. Our results show that modification of the guide RNA can mimic the effect of hyperactive mutants and advance the approach of recruiting endogenous ADARs for site-directed RNA editing.
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Affiliation(s)
- Erin E Doherty
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Xander E Wilcox
- Department of Chemistry, University of California, Davis, California 95616, United States
| | | | | | | | - Bart Klein
- ProQR Therapeutics, 2333 CK Leiden, The Netherlands
| | - Dean J Tantillo
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Andrew J Fisher
- Department of Chemistry, University of California, Davis, California 95616, United States
- Department of Molecular and Cellular Biology, University of California, Davis, California 95616, United States
| | - Peter A Beal
- Department of Chemistry, University of California, Davis, California 95616, United States
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32
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Sinnamon JR, Kim SY, Fisk JR, Song Z, Nakai H, Jeng S, McWeeney SK, Mandel G. In Vivo Repair of a Protein Underlying a Neurological Disorder by Programmable RNA Editing. Cell Rep 2021; 32:107878. [PMID: 32668243 PMCID: PMC7449137 DOI: 10.1016/j.celrep.2020.107878] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 05/08/2020] [Accepted: 06/16/2020] [Indexed: 02/07/2023] Open
Abstract
Programmable RNA editing is gaining momentum as an approach to repair mutations, but its efficiency in repairing endogenous mutant RNA in complex tissue is unknown. Here we apply this approach to the brain and successfully repair a guanosine-to-adenosine mutation in methyl CpG binding protein 2 RNA that causes the neurodevelopmental disease Rett syndrome. Repair is mediated by hippocampal injections of juvenile Mecp2317G>A mice with an adeno-associated virus expressing the hyperactive catalytic domain of adenosine deaminase acting on RNA 2 and Mecp2 guide. After 1 month, 50% of Mecp2 RNA is recoded in three different hippocampal neuronal populations. MeCP2 protein localization to heterochromatin is restored in neurons to 50% of wild-type levels. Whole-transcriptome RNA analysis of one neuronal population indicates that the majority of off-target editing sites exhibit rates of 30% or less. This study demonstrates that programmable RNA editing can be utilized to repair mutations in mouse models of neurological disease. Sinnamon et al. show that the Mecp2 guide-targeted “editase,” introduced by an adeno-associated virus into the hippocampus of a Rett syndrome mouse model, repairs a large fraction of pathological Mecp2G>A RNA. MeCP2 function, visualized by chromatin association in neurons, is repaired to similar levels. The results point toward a potential therapy for Rett syndrome.
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Affiliation(s)
- John R Sinnamon
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Susan Y Kim
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Jenna R Fisk
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Zhen Song
- Department of Molecular and Medical Genetics, Oregon Health and Science University, Portland, OR 97239, USA
| | - Hiroyuki Nakai
- Department of Molecular and Medical Genetics, Oregon Health and Science University, Portland, OR 97239, USA
| | - Sophia Jeng
- Division of Bioinformatics and Computational Biology, Department of Medical Informatics and Clinical Epidemiology, Knight Cancer Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Shannon K McWeeney
- Division of Bioinformatics and Computational Biology, Department of Medical Informatics and Clinical Epidemiology, Knight Cancer Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Gail Mandel
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA.
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33
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Liu X, Sun T, Shcherbina A, Li Q, Jarmoskaite I, Kappel K, Ramaswami G, Das R, Kundaje A, Li JB. Learning cis-regulatory principles of ADAR-based RNA editing from CRISPR-mediated mutagenesis. Nat Commun 2021; 12:2165. [PMID: 33846332 PMCID: PMC8041805 DOI: 10.1038/s41467-021-22489-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 03/15/2021] [Indexed: 11/24/2022] Open
Abstract
Adenosine-to-inosine (A-to-I) RNA editing catalyzed by ADAR enzymes occurs in double-stranded RNAs. Despite a compelling need towards predictive understanding of natural and engineered editing events, how the RNA sequence and structure determine the editing efficiency and specificity (i.e., cis-regulation) is poorly understood. We apply a CRISPR/Cas9-mediated saturation mutagenesis approach to generate libraries of mutations near three natural editing substrates at their endogenous genomic loci. We use machine learning to integrate diverse RNA sequence and structure features to model editing levels measured by deep sequencing. We confirm known features and identify new features important for RNA editing. Training and testing XGBoost algorithm within the same substrate yield models that explain 68 to 86 percent of substrate-specific variation in editing levels. However, the models do not generalize across substrates, suggesting complex and context-dependent regulation patterns. Our integrative approach can be applied to larger scale experiments towards deciphering the RNA editing code.
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Affiliation(s)
- Xin Liu
- Department of Genetics, Stanford University, Stanford, CA, USA
| | - Tao Sun
- Department of Genetics, Stanford University, Stanford, CA, USA
| | - Anna Shcherbina
- Department of Biomedical Data Science, Stanford University, Stanford, CA, USA
| | - Qin Li
- Department of Genetics, Stanford University, Stanford, CA, USA
| | | | - Kalli Kappel
- Biophysics Program, Stanford University, Stanford, CA, USA
| | - Gokul Ramaswami
- Department of Genetics, Stanford University, Stanford, CA, USA
| | - Rhiju Das
- Department of Biochemistry, Stanford University, Stanford, CA, USA
- Department of Physics, Stanford University, Stanford, CA, USA
| | - Anshul Kundaje
- Department of Genetics, Stanford University, Stanford, CA, USA.
- Department of Computer Science, Stanford University, Stanford, CA, USA.
| | - Jin Billy Li
- Department of Genetics, Stanford University, Stanford, CA, USA.
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34
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Erdmann EA, Mahapatra A, Mukherjee P, Yang B, Hundley HA. To protect and modify double-stranded RNA - the critical roles of ADARs in development, immunity and oncogenesis. Crit Rev Biochem Mol Biol 2020; 56:54-87. [PMID: 33356612 DOI: 10.1080/10409238.2020.1856768] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Adenosine deaminases that act on RNA (ADARs) are present in all animals and function to both bind double-stranded RNA (dsRNA) and catalyze the deamination of adenosine (A) to inosine (I). As inosine is a biological mimic of guanosine, deamination by ADARs changes the genetic information in the RNA sequence and is commonly referred to as RNA editing. Millions of A-to-I editing events have been reported for metazoan transcriptomes, indicating that RNA editing is a widespread mechanism used to generate molecular and phenotypic diversity. Loss of ADARs results in lethality in mice and behavioral phenotypes in worm and fly model systems. Furthermore, alterations in RNA editing occur in over 35 human pathologies, including several neurological disorders, metabolic diseases, and cancers. In this review, a basic introduction to ADAR structure and target recognition will be provided before summarizing how ADARs affect the fate of cellular RNAs and how researchers are using this knowledge to engineer ADARs for personalized medicine. In addition, we will highlight the important roles of ADARs and RNA editing in innate immunity and cancer biology.
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Affiliation(s)
- Emily A Erdmann
- Department of Biology, Indiana University, Bloomington, IN, USA
| | | | - Priyanka Mukherjee
- Medical Sciences Program, Indiana University School of Medicine-Bloomington, Bloomington, IN, USA
| | - Boyoon Yang
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
| | - Heather A Hundley
- Medical Sciences Program, Indiana University School of Medicine-Bloomington, Bloomington, IN, USA
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35
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Marina RJ, Brannan KW, Dong KD, Yee BA, Yeo GW. Evaluation of Engineered CRISPR-Cas-Mediated Systems for Site-Specific RNA Editing. Cell Rep 2020; 33:108350. [PMID: 33147453 PMCID: PMC8985550 DOI: 10.1016/j.celrep.2020.108350] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 09/30/2020] [Accepted: 10/13/2020] [Indexed: 12/17/2022] Open
Abstract
Site-directed RNA editing approaches offer great potential to correct genetic mutations in somatic cells while avoiding permanent off-target genomic edits. Nuclease-dead RNA-targeting CRISPR-Cas systems recruit functional effectors to RNA molecules in a programmable fashion. Here, we demonstrate a Streptococcus pyogenes Cas9-ADAR2 fusion system that uses a 3' modified guide RNA (gRNA) to enable adenosine-to-inosine (A-to-I) editing of specific bases on reporter and endogenously expressed mRNAs. Due to the sufficient nature of the 3' gRNA extension sequence, we observe that Cas9 gRNA spacer sequences are dispensable for directed RNA editing, revealing that Cas9 can act as an RNA-aptamer-binding protein. We demonstrate that Cas9-based A-to-I editing is comparable in on-target efficiency and off-target specificity with Cas13 RNA editing versions. This study provides a systematic benchmarking of RNA-targeting CRISPR-Cas designs for reversible nucleotide-level conversion at the transcriptome level.
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Affiliation(s)
- Ryan J Marina
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA; Stem Cell Program, University of California San Diego, La Jolla, CA 92093, USA; Institute for Genomic Medicine, University of California at San Diego, La Jolla, CA 92093, USA
| | - Kristopher W Brannan
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA; Stem Cell Program, University of California San Diego, La Jolla, CA 92093, USA; Institute for Genomic Medicine, University of California at San Diego, La Jolla, CA 92093, USA
| | - Kevin D Dong
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA; Stem Cell Program, University of California San Diego, La Jolla, CA 92093, USA; Institute for Genomic Medicine, University of California at San Diego, La Jolla, CA 92093, USA
| | - Brian A Yee
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA; Stem Cell Program, University of California San Diego, La Jolla, CA 92093, USA; Institute for Genomic Medicine, University of California at San Diego, La Jolla, CA 92093, USA
| | - Gene W Yeo
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA; Stem Cell Program, University of California San Diego, La Jolla, CA 92093, USA; Institute for Genomic Medicine, University of California at San Diego, La Jolla, CA 92093, USA.
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36
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Liu Y, Mao S, Huang S, Li Y, Chen Y, Di M, Huang X, Lv J, Wang X, Ge J, Shen S, Zhang X, Liu D, Huang X, Chi T. REPAIRx, a specific yet highly efficient programmable A > I RNA base editor. EMBO J 2020; 39:e104748. [PMID: 33058207 DOI: 10.15252/embj.2020104748] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 05/27/2020] [Accepted: 06/03/2020] [Indexed: 12/26/2022] Open
Abstract
Programmable A > I RNA editing is a valuable tool for basic research and medicine. A variety of editors have been created, but a genetically encoded editor that is both precise and efficient has not been described to date. The trade-off between precision and efficiency is exemplified in the state of the art editor REPAIR, which comprises the ADAR2 deaminase domain fused to dCas13b. REPAIR is highly efficient, but also causes significant off-target effects. Mutations that weaken the deaminase domain can minimize the undesirable effects, but this comes at the expense of on-target editing efficiency. We have now overcome this dilemma by using a multipronged approach: We have chosen an alternative Cas protein (CasRx), inserted the deaminase domain into the middle of CasRx, and redirected the editor to the nucleus. The new editor created, dubbed REPAIRx, is precise yet highly efficient, outperforming various previous versions on both mRNA and nuclear RNA targets. Thus, REPAIRx markedly expands the RNA editing toolkit and illustrates a novel strategy for base editor optimization.
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Affiliation(s)
- Yajing Liu
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China.,Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Shaoshuai Mao
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China.,Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China
| | - Shisheng Huang
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yongqin Li
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China.,Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China
| | - Yuxin Chen
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Minghui Di
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Xinxin Huang
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Junjun Lv
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Xinxin Wang
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China
| | - Jianyang Ge
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China
| | - Shengxi Shen
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Xiaoming Zhang
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Dahai Liu
- Department of Basic Medicine and Biomedical Engineering, School of Stomatology and Medicine, Foshan University, Foshan, China
| | - Xingxu Huang
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China
| | - Tian Chi
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China.,Department of Immunobiology, Yale University School of Medicine, New Haven, CT, USA
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37
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Morais P, Adachi H, Yu YT. Suppression of Nonsense Mutations by New Emerging Technologies. Int J Mol Sci 2020; 21:ijms21124394. [PMID: 32575694 PMCID: PMC7352488 DOI: 10.3390/ijms21124394] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 06/17/2020] [Accepted: 06/18/2020] [Indexed: 12/18/2022] Open
Abstract
Nonsense mutations often result from single nucleotide substitutions that change a sense codon (coding for an amino acid) to a nonsense or premature termination codon (PTC) within the coding region of a gene. The impact of nonsense mutations is two-fold: (1) the PTC-containing mRNA is degraded by a surveillance pathway called nonsense-mediated mRNA decay (NMD) and (2) protein translation stops prematurely at the PTC codon, and thus no functional full-length protein is produced. As such, nonsense mutations result in a large number of human diseases. Nonsense suppression is a strategy that aims to correct the defects of hundreds of genetic disorders and reverse disease phenotypes and conditions. While most clinical trials have been performed with small molecules, there is an increasing need for sequence-specific repair approaches that are safer and adaptable to personalized medicine. Here, we discuss recent advances in both conventional strategies as well as new technologies. Several of these will soon be tested in clinical trials as nonsense therapies, even if they still have some limitations and challenges to overcome.
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Affiliation(s)
- Pedro Morais
- ProQR Therapeutics, Zernikedreef 9, 2333 CK Leiden, The Netherlands;
| | - Hironori Adachi
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA;
| | - Yi-Tao Yu
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA;
- Correspondence: ; Tel.: +1-(585)-275-1271; Fax: +1-(585)-275-6007
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38
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Mali P. Humanizing Transcriptome Engineering. Cell 2020; 178:8-9. [PMID: 31251918 DOI: 10.1016/j.cell.2019.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Transcriptome targeting offers a tunable and reversible approach for cellular engineering. Accordingly, the ability to precisely perturb RNAs has broad implications for research and therapeutics. In this issue, Rauch and colleagues present a new addition to the RNA engineering toolbox that is modular, versatile, and built using human components.
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Affiliation(s)
- Prashant Mali
- Department of Bioengineering, University of California San Diego, San Diego, CA, USA.
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Fry LE, Peddle CF, Barnard AR, McClements ME, MacLaren RE. RNA editing as a therapeutic approach for retinal gene therapy requiring long coding sequences. Int J Mol Sci 2020; 21:ijms21030777. [PMID: 31991730 PMCID: PMC7037314 DOI: 10.3390/ijms21030777] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 01/20/2020] [Accepted: 01/21/2020] [Indexed: 12/26/2022] Open
Abstract
RNA editing aims to treat genetic disease through altering gene expression at the transcript level. Pairing site-directed RNA-targeting mechanisms with engineered deaminase enzymes allows for the programmable correction of G>A and T>C mutations in RNA. This offers a promising therapeutic approach for a range of genetic diseases. For inherited retinal degenerations caused by point mutations in large genes not amenable to single-adeno-associated viral (AAV) gene therapy such as USH2A and ABCA4, correcting RNA offers an alternative to gene replacement. Genome editing of RNA rather than DNA may offer an improved safety profile, due to the transient and potentially reversible nature of edits made to RNA. This review considers the current site-directing RNA editing systems, and the potential to translate these to the clinic for the treatment of inherited retinal degeneration.
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Affiliation(s)
- Lewis E. Fry
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
- Correspondence:
| | - Caroline F. Peddle
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
| | - Alun R. Barnard
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
| | - Michelle E. McClements
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
| | - Robert E. MacLaren
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
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41
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Novel Engineered Programmable Systems for ADAR-Mediated RNA Editing. MOLECULAR THERAPY. NUCLEIC ACIDS 2020; 19:1065-1072. [PMID: 32044725 PMCID: PMC7015837 DOI: 10.1016/j.omtn.2019.12.042] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 12/24/2019] [Accepted: 12/24/2019] [Indexed: 12/26/2022]
Abstract
One of the most prevalent forms of post-transcriptional RNA modification is the conversion of adenosine-to-inosine (A-to-I), mediated by adenosine deaminase acting on RNA (ADAR) enzymes. The advent of the CRISPR/Cas systems inspires researchers to work actively in the engineering of programmable RNA-guided machines for basic research and biomedical applications. In this regard, CIRTS (CRISPR-Cas-Inspired RNA Targeting System), RESCUE (RNA Editing for Specific C to U Exchange), RESTORE (Recruiting Endogenous ADAR to Specific Transcripts for Oligonucleotide-mediated RNA Editing), and LEAPER (Leveraging Endogenous ADAR for Programmable Editing of RNA) are innovative RNA base-editing platforms that have recently been engineered to perform programmable base conversions on target RNAs mediated by ADAR enzymes in mammalian cells. Thus, these four currently characterized RNA-editing systems constitute novel molecular tools with compelling programmability, specificity, and efficiency that show us some creative ways to take advantage of the engineered deaminases for precise base editing. Moreover, the advanced engineering of these systems permits editing of full-length transcripts containing disease-causing point mutations without the loss of genomic information, providing an attractive alternative for in vivo research and in the therapeutic setting if the challenges encountered in off-target edits and delivery are appropriately addressed. Here, I present an analytical approach of the current status and rapid progress of the novel ADAR-mediated RNA-editing systems when highlighting the qualities of each new RNA-editing platform and how these RNA-targeting strategies could be used to recruit human ADARs on endogenous transcripts, not only for our understanding of RNA-modification-mediated regulation of gene expression but also for editing clinically relevant mutations in a programmable and straightforward manner.
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Mao S, Liu Y, Huang S, Huang X, Chi T. Site-directed RNA editing (SDRE): Off-target effects and their countermeasures. J Genet Genomics 2019; 46:531-535. [PMID: 31889638 DOI: 10.1016/j.jgg.2019.11.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 10/08/2019] [Accepted: 11/04/2019] [Indexed: 12/20/2022]
Abstract
Site-directed RNA editing (SDRE) is invaluable to basic research and clinical applications and has emerged as a new frontier in genome editing. The past few years have witnessed a surge of interest in SDRE, with SDRE tools emerging at a breathtaking pace. However, off-target effects of SDRE remain a tough problem, which constitutes a major hurdle to their clinical applications. Here we discuss the diverse strategies for combating off-target editing, drawing lessons from the published studies as well as our ongoing research. Overall, SDRE is still at its infancy, with significant challenges and exciting opportunities ahead.
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Affiliation(s)
- Shaoshuai Mao
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, 201210, China; CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, 200031, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yajing Liu
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, 201210, China; CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, 200031, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shisheng Huang
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, 201210, China; CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, 200031, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xingxu Huang
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Tian Chi
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, 201210, China; Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06520, USA.
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43
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Programmable RNA editing by recruiting endogenous ADAR using engineered RNAs. Nat Biotechnol 2019; 37:1059-1069. [PMID: 31308540 DOI: 10.1038/s41587-019-0178-z] [Citation(s) in RCA: 148] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 06/04/2019] [Indexed: 12/19/2022]
Abstract
Current tools for targeted RNA editing rely on the delivery of exogenous proteins or chemically modified guide RNAs, which may lead to aberrant effector activity, delivery barrier or immunogenicity. Here, we present an approach, called leveraging endogenous ADAR for programmable editing of RNA (LEAPER), that employs short engineered ADAR-recruiting RNAs (arRNAs) to recruit native ADAR1 or ADAR2 enzymes to change a specific adenosine to inosine. We show that arRNA, delivered by a plasmid or viral vector or as a synthetic oligonucleotide, achieves editing efficiencies of up to 80%. LEAPER is highly specific, with rare global off-targets and limited editing of non-target adenosines in the target region. It is active in a broad spectrum of cell types, including multiple human primary cell types, and can restore α-L-iduronidase catalytic activity in Hurler syndrome patient-derived primary fibroblasts without evoking innate immune responses. As a single-molecule system, LEAPER enables precise, efficient RNA editing with broad applicability for therapy and basic research.
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44
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Azad MTA, Qulsum U, Tsukahara T. Comparative Activity of Adenosine Deaminase Acting on RNA (ADARs) Isoforms for Correction of Genetic Code in Gene Therapy. Curr Gene Ther 2019; 19:31-39. [DOI: 10.2174/1566523218666181114122116] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 11/12/2018] [Accepted: 11/13/2018] [Indexed: 12/26/2022]
Abstract
Introduction:
Members of the adenosine deaminase acting on RNA (ADAR) family of enzymes
consist of double-stranded RNA-binding domains (dsRBDs) and a deaminase domain (DD)
that converts adenosine (A) into inosine (I), which acts as guanosine (G) during translation. Using the
MS2 system, we engineered the DD of ADAR1 to direct it to a specific target. The aim of this work
was to compare the deaminase activities of ADAR1-DD and various isoforms of ADAR2-DD.
Materials and Methods:
We measured the binding affinity of the artificial enzyme system on a Biacore
™ X100. ADARs usually target dsRNA, so we designed a guide RNA complementary to the target
RNA, and then fused the guide sequence to the MS2 stem-loop. A mutated amber (TAG) stop
codon at 58 amino acid (TGG) of EGFP was targeted. After transfection of these three factors into
HEK 293 cells, we observed fluorescence signals of various intensities.
Results:
ADAR2-long without the Alu-cassette yielded a much higher fluorescence signal than
ADAR2-long with the Alu-cassette. With another isoform, ADAR2-short, which is 81 bp shorter at
the C-terminus, the fluorescence signal was undetectable. A single amino acid substitution of
ADAR2-long-DD (E488Q) rendered the enzyme more active than the wild type. The results of fluorescence
microscopy suggested that ADAR1-DD is more active than ADAR2-long-DD. Western blots
and sequencing confirmed that ADAR1-DD was more active than any other DD.
Conclusion:
This study provides information that should facilitate the rational use of ADAR variants
for genetic restoration and treatment of genetic diseases.
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Affiliation(s)
- Md. Thoufic A. Azad
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923- 1292, Japan
| | - Umme Qulsum
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923- 1292, Japan
| | - Toshifumi Tsukahara
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923- 1292, Japan
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Chen G, Katrekar D, Mali P. RNA-Guided Adenosine Deaminases: Advances and Challenges for Therapeutic RNA Editing. Biochemistry 2019; 58:1947-1957. [PMID: 30943016 DOI: 10.1021/acs.biochem.9b00046] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Targeted transcriptome engineering, in contrast to genome engineering, offers a complementary and potentially tunable and reversible strategy for cellular engineering. In this regard, adenosine to inosine (A-to-I) RNA base editing was recently engineered to make programmable base conversions on target RNAs. Similar to the DNA base editing technology, A-to-I RNA editing may offer an attractive alternative in a therapeutic setting, especially for the correction of point mutations. This Perspective introduces five currently characterized RNA editing systems and serves as a reader's guide for implementing an appropriate RNA editing strategy for applications in research or therapeutics.
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Affiliation(s)
- Genghao Chen
- Department of Bioengineering , University of California, San Diego , La Jolla , California 92093-0412 , United States
| | - Dhruva Katrekar
- Department of Bioengineering , University of California, San Diego , La Jolla , California 92093-0412 , United States
| | - Prashant Mali
- Department of Bioengineering , University of California, San Diego , La Jolla , California 92093-0412 , United States
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46
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Katrekar D, Chen G, Meluzzi D, Ganesh A, Worlikar A, Shih YR, Varghese S, Mali P. In vivo RNA editing of point mutations via RNA-guided adenosine deaminases. Nat Methods 2019; 16:239-242. [PMID: 30737497 PMCID: PMC6395520 DOI: 10.1038/s41592-019-0323-0] [Citation(s) in RCA: 124] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 12/13/2018] [Indexed: 12/16/2022]
Abstract
We present in vivo sequence-specific RNA base editing via adenosine deaminases acting on RNA (ADAR) enzymes with associated ADAR guide RNAs (adRNAs). To achieve this, we systematically engineered adRNAs to harness ADARs, and comprehensively evaluated the specificity and activity of the toolsets in vitro and in vivo via two mouse models of human disease. We anticipate that this platform will enable tunable and reversible engineering of cellular RNAs for diverse applications.
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Affiliation(s)
- Dhruva Katrekar
- Department of Bioengineering, University of California, San Diego, CA, USA
| | - Genghao Chen
- Department of Bioengineering, University of California, San Diego, CA, USA
| | - Dario Meluzzi
- Department of Bioengineering, University of California, San Diego, CA, USA
| | - Ashwin Ganesh
- Department of Bioengineering, University of California, San Diego, CA, USA
| | - Atharv Worlikar
- Department of Bioengineering, University of California, San Diego, CA, USA
| | - Yu-Ru Shih
- Department of Bioengineering, University of California, San Diego, CA, USA
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Shyni Varghese
- Department of Bioengineering, University of California, San Diego, CA, USA
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Prashant Mali
- Department of Bioengineering, University of California, San Diego, CA, USA.
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47
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Montiel-Gonzalez MF, Diaz Quiroz JF, Rosenthal JJC. Current strategies for Site-Directed RNA Editing using ADARs. Methods 2019; 156:16-24. [PMID: 30502398 PMCID: PMC6814296 DOI: 10.1016/j.ymeth.2018.11.016] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Revised: 11/22/2018] [Accepted: 11/27/2018] [Indexed: 12/26/2022] Open
Abstract
Adenosine Deaminases that Act on RNA (ADARs) are a group of enzymes that catalyze the conversion of adenosines (A's) to inosines (I's) in a process known as RNA editing. Though ADARs can act on different types of RNA, editing events in coding regions of mRNA are of particular interest as I's base pair like guanosines (G's). Thus, every A-to-I change catalyzed by ADAR is read as an A-to-G change during translation, potentially altering protein sequence and function. This ability to re-code makes ADAR an attractive therapeutic tool to correct genetic mutations within mRNA. The main challenge in doing so is to re-direct ADAR's catalytic activity towards A's that are not naturally edited, a process termed Site-Directed RNA Editing (SDRE). Recently, a handful of labs have taken up this challenge and two basic strategies have emerged. The first involves redirecting endogenous ADAR to new sites by making editable structures using antisense RNA oligonucleotides. The second also utilizes antisense RNA oligonucleotides, but it uses them as guides to deliver the catalytic domain of engineered ADARs to new sites, much as CRISPR guides deliver Cas nucleases. In fact, despite the intense current focus on CRISPR-Cas9 genome editing, SDRE offers a number of distinct advantages. In the present review we will discuss these strategies in greater detail, focusing on the concepts on which they are based, how they were developed and tested, and their respective advantages and disadvantages. Though the precise and efficient re-direction of ADAR activity still remains a challenge, the systems that are being developed lay the foundation for SDRE as a powerful tool for transient genome editing.
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MESH Headings
- Adenosine/metabolism
- Adenosine Deaminase/genetics
- Adenosine Deaminase/metabolism
- Animals
- CRISPR-Associated Protein 9/genetics
- CRISPR-Associated Protein 9/metabolism
- CRISPR-Cas Systems
- Genome, Human
- Humans
- Inosine/metabolism
- Mutagenesis, Site-Directed/methods
- Oligoribonucleotides, Antisense/genetics
- Oligoribonucleotides, Antisense/metabolism
- Protein Domains
- RNA Editing
- RNA, Guide, CRISPR-Cas Systems/genetics
- RNA, Guide, CRISPR-Cas Systems/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA-Binding Proteins/genetics
- RNA-Binding Proteins/metabolism
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48
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Monteleone LR, Matthews MM, Palumbo CM, Thomas JM, Zheng Y, Chiang Y, Fisher AJ, Beal PA. A Bump-Hole Approach for Directed RNA Editing. Cell Chem Biol 2019; 26:269-277.e5. [PMID: 30581135 PMCID: PMC6386613 DOI: 10.1016/j.chembiol.2018.10.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 09/28/2018] [Accepted: 10/26/2018] [Indexed: 12/17/2022]
Abstract
Molecules capable of directing changes to nucleic acid sequences are powerful tools for molecular biology and promising candidates for the therapeutic correction of disease-causing mutations. However, unwanted reactions at off-target sites complicate their use. Here we report selective combinations of mutant editing enzyme and directing oligonucleotide. Mutations in human ADAR2 (adenosine deaminase acting on RNA 2) that introduce aromatic amino acids at position 488 reduce background RNA editing. This residue is juxtaposed to the nucleobase that pairs with the editing site adenine, suggesting a steric clash for the bulky mutants. Replacing this nucleobase with a hydrogen atom removes the clash and restores editing activity. A crystal structure of the E488Y mutant bound to abasic site-containing RNA shows the accommodation of the tyrosine side chain. Finally, we demonstrate directed RNA editing in vitro and in human cells using mutant ADAR2 proteins and modified guide RNAs with reduced off-target activity.
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Affiliation(s)
- Leanna R Monteleone
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA 95616, USA
| | - Melissa M Matthews
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA 95616, USA
| | - Cody M Palumbo
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA 95616, USA
| | - Justin M Thomas
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA 95616, USA
| | - Yuxuan Zheng
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA 95616, USA
| | - Yao Chiang
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA 95616, USA
| | - Andrew J Fisher
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA 95616, USA; Department of Molecular and Cellular Biology, University of California, One Shields Avenue, Davis, CA 95616, USA
| | - Peter A Beal
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA 95616, USA.
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49
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Precise RNA editing by recruiting endogenous ADARs with antisense oligonucleotides. Nat Biotechnol 2019; 37:133-138. [PMID: 30692694 DOI: 10.1038/s41587-019-0013-6] [Citation(s) in RCA: 162] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 12/11/2018] [Indexed: 12/15/2022]
Abstract
Site-directed RNA editing might provide a safer or more effective alternative to genome editing in certain clinical scenarios. Until now, RNA editing has relied on overexpression of exogenous RNA editing enzymes or of endogenous human ADAR (adenosine deaminase acting on RNA) enzymes. Here we describe the engineering of chemically optimized antisense oligonucleotides that recruit endogenous human ADARs to edit endogenous transcripts in a simple and programmable way, an approach we call RESTORE (recruiting endogenous ADAR to specific transcripts for oligonucleotide-mediated RNA editing). We observed almost no off-target editing, and natural editing homeostasis was not perturbed. We successfully applied RESTORE to a panel of standard human cell lines and human primary cells and demonstrated repair of the clinically relevant PiZZ mutation, which causes α1-antitrypsin deficiency, and editing of phosphotyrosine 701 in STAT1, the activity switch of the signaling factor. RESTORE requires only the administration of an oligonucleotide, circumvents ectopic expression of proteins, and represents an attractive approach for drug development.
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50
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Gulei D, Raduly L, Berindan-Neagoe I, Calin GA. CRISPR-based RNA editing: diagnostic applications and therapeutic options. Expert Rev Mol Diagn 2019; 19:83-88. [DOI: 10.1080/14737159.2019.1568242] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Diana Gulei
- MedFuture Research Center for Advanced Medicine, University of Medicine and Pharmacy “Iuliu-Hatieganu”, Cluj-Napoca, Romania
| | - Lajos Raduly
- Research Center for Functional Genomics, Biomedicine and Translational Medicine, University of Medicine and Pharmacy “Iuliu-Hatieganu”, Cluj-Napoca, Romania
- Department of Pathophysiology, University of Agricultural Sciences and Veterinary Medicine, Cluj-Napoca, Romania
| | - Ioana Berindan-Neagoe
- MedFuture Research Center for Advanced Medicine, University of Medicine and Pharmacy “Iuliu-Hatieganu”, Cluj-Napoca, Romania
- Research Center for Functional Genomics, Biomedicine and Translational Medicine, University of Medicine and Pharmacy “Iuliu-Hatieganu”, Cluj-Napoca, Romania
- Department of Functional Genomics and Experimental Pathology, The Oncology Institute “Prof. Dr. Ion Chiricuţă”, Cluj-Napoca, Romania
| | - George Adrian Calin
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX
- Center for RNA Inference and Non-Coding RNAs, The University of Texas MD Anderson Cancer Center, Houston, TXUSA
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