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Ward C, Beharry A, Tennakoon R, Rozik P, Wilhelm SDP, Heinemann IU, O’Donoghue P. Mechanisms and Delivery of tRNA Therapeutics. Chem Rev 2024; 124:7976-8008. [PMID: 38801719 PMCID: PMC11212642 DOI: 10.1021/acs.chemrev.4c00142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 04/11/2024] [Accepted: 04/26/2024] [Indexed: 05/29/2024]
Abstract
Transfer ribonucleic acid (tRNA) therapeutics will provide personalized and mutation specific medicines to treat human genetic diseases for which no cures currently exist. The tRNAs are a family of adaptor molecules that interpret the nucleic acid sequences in our genes into the amino acid sequences of proteins that dictate cell function. Humans encode more than 600 tRNA genes. Interestingly, even healthy individuals contain some mutant tRNAs that make mistakes. Missense suppressor tRNAs insert the wrong amino acid in proteins, and nonsense suppressor tRNAs read through premature stop signals to generate full length proteins. Mutations that underlie many human diseases, including neurodegenerative diseases, cancers, and diverse rare genetic disorders, result from missense or nonsense mutations. Thus, specific tRNA variants can be strategically deployed as therapeutic agents to correct genetic defects. We review the mechanisms of tRNA therapeutic activity, the nature of the therapeutic window for nonsense and missense suppression as well as wild-type tRNA supplementation. We discuss the challenges and promises of delivering tRNAs as synthetic RNAs or as gene therapies. Together, tRNA medicines will provide novel treatments for common and rare genetic diseases in humans.
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Affiliation(s)
- Cian Ward
- Department of Biochemistry, Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Aruun Beharry
- Department of Biochemistry, Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Rasangi Tennakoon
- Department of Biochemistry, Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Peter Rozik
- Department of Biochemistry, Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Sarah D. P. Wilhelm
- Department of Biochemistry, Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Ilka U. Heinemann
- Department of Biochemistry, Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Patrick O’Donoghue
- Department of Biochemistry, Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
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2
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Ruan J, Yu X, Xu H, Cui W, Zhang K, Liu C, Sun W, Huang X, An L, Zhang Y. Suppressor tRNA in gene therapy. SCIENCE CHINA. LIFE SCIENCES 2024:10.1007/s11427-024-2613-y. [PMID: 38926247 DOI: 10.1007/s11427-024-2613-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 05/08/2024] [Indexed: 06/28/2024]
Abstract
Suppressor tRNAs are engineered or naturally occurring transfer RNA molecules that have shown promise in gene therapy for diseases caused by nonsense mutations, which result in premature termination codons (PTCs) in coding sequence, leading to truncated, often nonfunctional proteins. Suppressor tRNAs can recognize and pair with these PTCs, allowing the ribosome to continue translation and produce a full-length protein. This review introduces the mechanism and development of suppressor tRNAs, compares suppressor tRNAs with other readthrough therapies, discusses their potential for clinical therapy, limitations, and obstacles. We also summarize the applications of suppressor tRNAs in both in vitro and in vivo, offering new insights into the research and treatment of nonsense mutation diseases.
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Affiliation(s)
- Jingjing Ruan
- The Children's Hospital, National Clinical Research Center for Child Health, Zhejiang University School of Medicine, Liangzhu Laboratory, Hangzhou, 310000, China
- Liangzhu Laboratory, Zhejiang University School of Medicine, Hangzhou, 311121, China
| | - Xiaoxiao Yu
- Liangzhu Laboratory, Zhejiang University School of Medicine, Hangzhou, 311121, China
| | - Huixia Xu
- Department of Thoracic and Cardiovascular Surgery, Huaihe Hospital of Henan University, Henan University, Kaifeng, 475000, China
| | - Wenrui Cui
- Translational Medicine Center, Huaihe Hospital of Henan University, Henan University, Kaifeng, 475000, China
| | - Kaiye Zhang
- Eye Center, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310009, China
| | - Chenyang Liu
- Translational Medicine Center, Huaihe Hospital of Henan University, Henan University, Kaifeng, 475000, China
| | - Wenlong Sun
- Liangzhu Laboratory, Zhejiang University School of Medicine, Hangzhou, 311121, China
| | - Xiaodan Huang
- Eye Center, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310009, China
| | - Lei An
- Translational Medicine Center, Huaihe Hospital of Henan University, Henan University, Kaifeng, 475000, China.
| | - Yue Zhang
- The Children's Hospital, National Clinical Research Center for Child Health, Zhejiang University School of Medicine, Liangzhu Laboratory, Hangzhou, 310000, China.
- Liangzhu Laboratory, Zhejiang University School of Medicine, Hangzhou, 311121, China.
- Translational Medicine Center, Huaihe Hospital of Henan University, Henan University, Kaifeng, 475000, China.
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3
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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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4
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Awawdeh A, Radecki AA, Vargas-Rodriguez O. Suppressor tRNAs at the interface of genetic code expansion and medicine. Front Genet 2024; 15:1420331. [PMID: 38798701 PMCID: PMC11116698 DOI: 10.3389/fgene.2024.1420331] [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: 04/19/2024] [Accepted: 04/29/2024] [Indexed: 05/29/2024] Open
Abstract
Suppressor transfer RNAs (sup-tRNAs) are receiving renewed attention for their promising therapeutic properties in treating genetic diseases caused by nonsense mutations. Traditionally, sup-tRNAs have been created by replacing the anticodon sequence of native tRNAs with a suppressor sequence. However, due to their complex interactome, considering other structural and functional tRNA features for design and engineering can yield more effective sup-tRNA therapies. For over 2 decades, the field of genetic code expansion (GCE) has created a wealth of knowledge, resources, and tools to engineer sup-tRNAs. In this Mini Review, we aim to shed light on how existing knowledge and strategies to develop sup-tRNAs for GCE can be adopted to accelerate the discovery of efficient and specific sup-tRNAs for medical treatment options. We highlight methods and milestones and discuss how these approaches may enlighten the research and development of tRNA medicines.
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Affiliation(s)
| | | | - Oscar Vargas-Rodriguez
- Department of Molecular Biology and Biophysics, University of Connecticut School of Medicine, Farmington, CT, United States
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5
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Hou Y, Zhang W, McGilvray PT, Sobczyk M, Wang T, Weng SHS, Huff A, Huang S, Pena N, Katanski CD, Pan T. Engineered mischarged transfer RNAs for correcting pathogenic missense mutations. Mol Ther 2024; 32:352-371. [PMID: 38104240 PMCID: PMC10861979 DOI: 10.1016/j.ymthe.2023.12.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 11/08/2023] [Accepted: 12/11/2023] [Indexed: 12/19/2023] Open
Abstract
Missense mutations account for approximately 50% of pathogenic mutations in human genetic diseases, and most lack effective treatments. Gene therapies, gene editing, and RNA therapies, including transfer RNA (tRNA) modalities, are common strategies for genetic disease treatments. However, reported tRNA therapies are for nonsense mutations only. It has not been explored how tRNAs can be engineered to correct missense mutations. Here, we describe missense-correcting tRNAs (mc-tRNAs) as a potential therapeutic for correcting pathogenic missense mutations. Mc-tRNAs are engineered tRNAs charged with one amino acid, but read codons of another in translation. We first developed a series of fluorescent protein-based reporters that indicate the successful correction of missense mutations via restoration of fluorescence. We engineered mc-tRNAs that effectively corrected serine and arginine missense mutations in the reporters and confirmed the amino acid substitution by mass spectrometry and mc-tRNA expression by sequencing. We examined the transcriptome response to mc-tRNA expression and found some mc-tRNAs induced minimum transcriptomic changes. Furthermore, we applied an mc-tRNA to rescue a pathogenic CAPN3 Arg-to-Gln mutant involved in LGMD2A. These results establish a versatile pipeline for mc-tRNA engineering and demonstrate the potential of mc-tRNA as an alternative therapeutic platform for the treatment of genetic disorders.
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Affiliation(s)
- Yichen Hou
- Committee on Genomics, Genetics and Systems Biology, University of Chicago, Chicago, IL 60637, USA
| | - Wen Zhang
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | | | - Marek Sobczyk
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Tianxin Wang
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | | | - Allen Huff
- Proteomics Platform, University of Chicago, Chicago, IL 60637, USA
| | - Sihao Huang
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Noah Pena
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | | | - Tao Pan
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA.
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6
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Coller J, Ignatova Z. tRNA therapeutics for genetic diseases. Nat Rev Drug Discov 2024; 23:108-125. [PMID: 38049504 DOI: 10.1038/s41573-023-00829-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/11/2023] [Indexed: 12/06/2023]
Abstract
Transfer RNAs (tRNAs) have a crucial role in protein synthesis, and in recent years, their therapeutic potential for the treatment of genetic diseases - primarily those associated with a mutation altering mRNA translation - has gained significant attention. Engineering tRNAs to readthrough nonsense mutation-associated premature termination of mRNA translation can restore protein synthesis and function. In addition, supplementation of natural tRNAs can counteract effects of missense mutations in proteins crucial for tRNA biogenesis and function in translation. This Review will present advances in the development of tRNA therapeutics with high activity and safety in vivo and discuss different formulation approaches for single or chronic treatment modalities. The field of tRNA therapeutics is still in its early stages, and a series of challenges related to tRNA efficacy and stability in vivo, delivery systems with tissue-specific tropism, and safe and efficient manufacturing need to be addressed.
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Affiliation(s)
- Jeff Coller
- Department of Molecular Biology and Genetics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA.
| | - Zoya Ignatova
- Institute of Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany.
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7
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Manjunath LE, Singh A, Som S, Eswarappa SM. Mammalian proteome expansion by stop codon readthrough. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 14:e1739. [PMID: 35570338 DOI: 10.1002/wrna.1739] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 04/11/2022] [Accepted: 04/16/2022] [Indexed: 12/20/2022]
Abstract
Recognition of a stop codon by translation machinery as a sense codon results in translational readthrough instead of termination. This recoding process, termed stop codon readthrough (SCR) or translational readthrough, is found in all domains of life including mammals. The context of the stop codon, local mRNA topology, and molecules that interact with the mRNA region downstream of the stop codon determine SCR. The products of SCR can have localization, stability, and function different from those of the canonical isoforms. In this review, we discuss how recent technological and computational advances have increased our understanding of the SCR process in the mammalian system. Based on the known molecular events that occur during SCR of multiple mRNAs, we propose transient molecular roadblocks on an mRNA downstream of the stop codon as a possible mechanism for the induction of SCR. We argue, with examples, that the insights gained from the natural SCR events can guide us to develop novel strategies for the treatment of diseases caused by premature stop codons. This article is categorized under: Translation > Regulation.
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Affiliation(s)
- Lekha E Manjunath
- Department of Biochemistry, Indian Institute of Science, Bengaluru, Karnataka, India
| | - Anumeha Singh
- Department of Biochemistry, Indian Institute of Science, Bengaluru, Karnataka, India
| | - Saubhik Som
- Department of Biochemistry, Indian Institute of Science, Bengaluru, Karnataka, India
| | - Sandeep M Eswarappa
- Department of Biochemistry, Indian Institute of Science, Bengaluru, Karnataka, India
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8
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Ko W, Porter JJ, Sipple MT, Edwards KM, Lueck JD. Efficient suppression of endogenous CFTR nonsense mutations using anticodon-engineered transfer RNAs. MOLECULAR THERAPY. NUCLEIC ACIDS 2022; 28:685-701. [PMID: 35664697 PMCID: PMC9126842 DOI: 10.1016/j.omtn.2022.04.033] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 04/29/2022] [Indexed: 12/14/2022]
Abstract
Nonsense mutations or premature termination codons (PTCs) comprise ∼11% of all genetic lesions, which result in over 7,000 distinct genetic diseases. Due to their outsized impact on human health, considerable effort has been made to find therapies for nonsense-associated diseases. Suppressor tRNAs have long been identified as a possible therapeutic for nonsense-associated diseases; however, their ability to inhibit nonsense-mediated mRNA decay (NMD) and support significant protein translation from endogenous transcripts has not been determined in mammalian cells. Here, we investigated the ability of anticodon edited (ACE)-tRNAs to suppress cystic fibrosis (CF) causing PTCs in the cystic fibrosis transmembrane regulator (CFTR) gene in gene-edited immortalized human bronchial epithelial (16HBEge) cells. Delivery of ACE-tRNAs to 16HBEge cells harboring three common CF mutations G542XUGA-, R1162XUGA-, and W1282XUGA-CFTR PTCs significantly inhibited NMD and rescued endogenous mRNA expression. Furthermore, delivery of our highly active leucine-encoding ACE-tRNA resulted in rescue of W1282X-CFTR channel function to levels that significantly exceed the necessary CFTR channel function for therapeutic relevance. This study establishes the ACE-tRNA approach as a potential standalone therapeutic for nonsense-associated diseases due to its ability to rescue both mRNA and full-length protein expression from PTC-containing endogenous genes.
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Affiliation(s)
- Wooree Ko
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Joseph J. Porter
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Matthew T. Sipple
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Katherine M. Edwards
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - John D. Lueck
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
- Department of Neurology, University of Rochester Medical Center, Rochester, NY 14642, USA
- Center for RNA Biology, University of Rochester Medical Center, Rochester, NY 14642, USA
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9
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Yu J, Tang B, He X, Zou P, Zeng Z, Xiao R. Nonsense Suppression Therapy: An Emerging Treatment for Hereditary Skin Diseases. Acta Derm Venereol 2022; 102:adv00658. [DOI: 10.2340/actadv.v102.353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Nonsense mutations cause the premature termination of protein translation via premature termination codons (PTCs), leading to the synthesis of incomplete functional proteins and causing large numbers of genetic disorders. The emergence of nonsense suppression therapy is considered to be an effective method for the treatment of hereditary diseases, but its application in hereditary skin diseases is relatively limited. This review summarizes the current research status of nonsense suppression therapy for hereditary skin diseases, and discusses the potential opportunities and challenges of applying new technologies related to nonsense suppression therapy to dermatology. Further research is needed into the possible use of nonsense suppression therapy as a strategy for the safer and specific treatment of hereditary skin diseases.
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10
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Porter JJ, Heil CS, Lueck JD. Therapeutic promise of engineered nonsense suppressor tRNAs. WILEY INTERDISCIPLINARY REVIEWS. RNA 2021; 12:e1641. [PMID: 33567469 PMCID: PMC8244042 DOI: 10.1002/wrna.1641] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 12/16/2020] [Accepted: 12/23/2020] [Indexed: 12/11/2022]
Abstract
Nonsense mutations change an amino acid codon to a premature termination codon (PTC) generally through a single-nucleotide substitution. The generation of a PTC results in a defective truncated protein and often in severe forms of disease. Because of the exceedingly high prevalence of nonsense-associated diseases and a unifying mechanism, there has been a concerted effort to identify PTC therapeutics. Most clinical trials for PTC therapeutics have been conducted with small molecules that promote PTC read through and incorporation of a near-cognate amino acid. However, there is a need for PTC suppression agents that recode PTCs with the correct amino acid while being applicable to PTC mutations in many different genomic landscapes. With these characteristics, a single therapeutic will be able to treat several disease-causing PTCs. In this review, we will focus on the use of nonsense suppression technologies, in particular, suppressor tRNAs (sup-tRNAs), as possible therapeutics for correcting PTCs. Sup-tRNAs have many attractive qualities as possible therapeutic agents although there are knowledge gaps on their function in mammalian cells and technical hurdles that need to be overcome before their promise is realized. This article is categorized under: RNA Processing > tRNA Processing Translation > Translation Regulation.
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Affiliation(s)
- Joseph J. Porter
- Department of Pharmacology and PhysiologyUniversity of Rochester Medical CenterRochesterNew YorkUSA
| | - Christina S. Heil
- Department of Pharmacology and PhysiologyUniversity of Rochester Medical CenterRochesterNew YorkUSA
| | - John D. Lueck
- Department of Pharmacology and PhysiologyUniversity of Rochester Medical CenterRochesterNew YorkUSA
- Department of NeurologyUniversity of Rochester Medical CenterRochesterNew YorkUSA
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11
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Albers S, Beckert B, Matthies MC, Mandava CS, Schuster R, Seuring C, Riedner M, Sanyal S, Torda AE, Wilson DN, Ignatova Z. Repurposing tRNAs for nonsense suppression. Nat Commun 2021; 12:3850. [PMID: 34158503 PMCID: PMC8219837 DOI: 10.1038/s41467-021-24076-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 06/01/2021] [Indexed: 02/06/2023] Open
Abstract
Three stop codons (UAA, UAG and UGA) terminate protein synthesis and are almost exclusively recognized by release factors. Here, we design de novo transfer RNAs (tRNAs) that efficiently decode UGA stop codons in Escherichia coli. The tRNA designs harness various functionally conserved aspects of sense-codon decoding tRNAs. Optimization within the TΨC-stem to stabilize binding to the elongation factor, displays the most potent effect in enhancing suppression activity. We determine the structure of the ribosome in a complex with the designed tRNA bound to a UGA stop codon in the A site at 2.9 Å resolution. In the context of the suppressor tRNA, the conformation of the UGA codon resembles that of a sense-codon rather than when canonical translation termination release factors are bound, suggesting conformational flexibility of the stop codons dependent on the nature of the A-site ligand. The systematic analysis, combined with structural insights, provides a rationale for targeted repurposing of tRNAs to correct devastating nonsense mutations that introduce a premature stop codon.
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Affiliation(s)
- Suki Albers
- grid.9026.d0000 0001 2287 2617Institute of Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany
| | - Bertrand Beckert
- grid.9026.d0000 0001 2287 2617Institute of Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany
| | - Marco C. Matthies
- grid.9026.d0000 0001 2287 2617Center for Bioinformatics, University of Hamburg, Hamburg, Germany
| | - Chandra Sekhar Mandava
- grid.8993.b0000 0004 1936 9457Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Raphael Schuster
- grid.9026.d0000 0001 2287 2617Institute of Organic Chemistry, University of Hamburg, Hamburg, Germany
| | | | - Maria Riedner
- grid.9026.d0000 0001 2287 2617Institute of Organic Chemistry, University of Hamburg, Hamburg, Germany
| | - Suparna Sanyal
- grid.8993.b0000 0004 1936 9457Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Andrew E. Torda
- grid.9026.d0000 0001 2287 2617Center for Bioinformatics, University of Hamburg, Hamburg, Germany
| | - Daniel N. Wilson
- grid.9026.d0000 0001 2287 2617Institute of Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany
| | - Zoya Ignatova
- grid.9026.d0000 0001 2287 2617Institute of Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany
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12
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Martins-Dias P, Romão L. Nonsense suppression therapies in human genetic diseases. Cell Mol Life Sci 2021; 78:4677-4701. [PMID: 33751142 PMCID: PMC11073055 DOI: 10.1007/s00018-021-03809-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 02/06/2021] [Accepted: 03/05/2021] [Indexed: 02/06/2023]
Abstract
About 11% of all human disease-associated gene lesions are nonsense mutations, resulting in the introduction of an in-frame premature translation-termination codon (PTC) into the protein-coding gene sequence. When translated, PTC-containing mRNAs originate truncated and often dysfunctional proteins that might be non-functional or have gain-of-function or dominant-negative effects. Therapeutic strategies aimed at suppressing PTCs to restore deficient protein function-the so-called nonsense suppression (or PTC readthrough) therapies-have the potential to provide a therapeutic benefit for many patients and in a broad range of genetic disorders, including cancer. These therapeutic approaches comprise the use of translational readthrough-inducing compounds that make the translational machinery recode an in-frame PTC into a sense codon. However, most of the mRNAs carrying a PTC can be rapidly degraded by the surveillance mechanism of nonsense-mediated decay (NMD), thus decreasing the levels of PTC-containing mRNAs in the cell and their availability for PTC readthrough. Accordingly, the use of NMD inhibitors, or readthrough-compound potentiators, may enhance the efficiency of PTC suppression. Here, we review the mechanisms of PTC readthrough and their regulation, as well as the recent advances in the development of novel approaches for PTC suppression, and their role in personalized medicine.
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Affiliation(s)
- Patrícia Martins-Dias
- Department of Human Genetics, Instituto Nacional de Saúde Doutor Ricardo Jorge, Av. Padre Cruz, 1649-016, Lisbon, Portugal
- Faculty of Sciences, BioISI-Biosystems and Integrative Sciences Institute, University of Lisboa, 1749-016, Lisbon, Portugal
| | - Luísa Romão
- Department of Human Genetics, Instituto Nacional de Saúde Doutor Ricardo Jorge, Av. Padre Cruz, 1649-016, Lisbon, Portugal.
- Faculty of Sciences, BioISI-Biosystems and Integrative Sciences Institute, University of Lisboa, 1749-016, Lisbon, Portugal.
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13
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Nonsense Suppression Therapy: New Hypothesis for the Treatment of Inherited Bone Marrow Failure Syndromes. Int J Mol Sci 2020; 21:ijms21134672. [PMID: 32630050 PMCID: PMC7369780 DOI: 10.3390/ijms21134672] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 06/29/2020] [Accepted: 06/29/2020] [Indexed: 12/13/2022] Open
Abstract
Inherited bone marrow failure syndromes (IBMFS) are a group of cancer-prone genetic diseases characterized by hypocellular bone marrow with impairment in one or more hematopoietic lineages. The pathogenesis of IBMFS involves mutations in several genes which encode for proteins involved in DNA repair, telomere biology and ribosome biogenesis. The classical IBMFS include Shwachman–Diamond syndrome (SDS), Diamond–Blackfan anemia (DBA), Fanconi anemia (FA), dyskeratosis congenita (DC), and severe congenital neutropenia (SCN). IBMFS are associated with high risk of myelodysplastic syndrome (MDS), acute myeloid leukemia (AML), and solid tumors. Unfortunately, no specific pharmacological therapies have been highly effective for IBMFS. Hematopoietic stem cell transplantation provides a cure for aplastic or myeloid neoplastic complications. However, it does not affect the risk of solid tumors. Since approximately 28% of FA, 24% of SCN, 21% of DBA, 20% of SDS, and 17% of DC patients harbor nonsense mutations in the respective IBMFS-related genes, we discuss the use of the nonsense suppression therapy in these diseases. We recently described the beneficial effect of ataluren, a nonsense suppressor drug, in SDS bone marrow hematopoietic cells ex vivo. A similar approach could be therefore designed for treating other IBMFS. In this review we explain in detail the new generation of nonsense suppressor molecules and their mechanistic roles. Furthermore, we will discuss strengths and limitations of these molecules which are emerging from preclinical and clinical studies. Finally we discuss the state-of-the-art of preclinical and clinical therapeutic studies carried out for IBMFS.
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14
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Leier A, Bedwell DM, Chen AT, Dickson G, Keeling KM, Kesterson RA, Korf BR, Marquez Lago TT, Müller UF, Popplewell L, Zhou J, Wallis D. Mutation-Directed Therapeutics for Neurofibromatosis Type I. MOLECULAR THERAPY. NUCLEIC ACIDS 2020; 20:739-753. [PMID: 32408052 PMCID: PMC7225739 DOI: 10.1016/j.omtn.2020.04.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 04/20/2020] [Accepted: 04/23/2020] [Indexed: 02/07/2023]
Abstract
Significant advances in biotechnology have led to the development of a number of different mutation-directed therapies. Some of these techniques have matured to a level that has allowed testing in clinical trials, but few have made it to approval by drug-regulatory bodies for the treatment of specific diseases. While there are still various hurdles to be overcome, recent success stories have proven the potential power of mutation-directed therapies and have fueled the hope of finding therapeutics for other genetic disorders. In this review, we summarize the state-of-the-art of various therapeutic approaches and assess their applicability to the genetic disorder neurofibromatosis type I (NF1). NF1 is caused by the loss of function of neurofibromin, a tumor suppressor and downregulator of the Ras signaling pathway. The condition is characterized by a variety of phenotypes and includes symptoms such as skin spots, nervous system tumors, skeletal dysplasia, and others. Hence, depending on the patient, therapeutics may need to target different tissues and cell types. While we also discuss the delivery of therapeutics, in particular via viral vectors and nanoparticles, our main focus is on therapeutic techniques that reconstitute functional neurofibromin, most notably cDNA replacement, CRISPR-based DNA repair, RNA repair, antisense oligonucleotide therapeutics including exon skipping, and nonsense suppression.
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Affiliation(s)
- Andre Leier
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - David M Bedwell
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Ann T Chen
- Department of Neurosurgery, Yale University, New Haven, CT 06510, USA
| | - George Dickson
- Centre of Biomedical Sciences, Department of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK
| | - Kim M Keeling
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Robert A Kesterson
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Bruce R Korf
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | | | - Ulrich F Müller
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093, USA
| | - Linda Popplewell
- Centre of Biomedical Sciences, Department of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK
| | - Jiangbing Zhou
- Department of Neurosurgery, Yale University, New Haven, CT 06510, USA
| | - Deeann Wallis
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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15
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Lueck JD, Yoon JS, Perales-Puchalt A, Mackey AL, Infield DT, Behlke MA, Pope MR, Weiner DB, Skach WR, McCray PB, Ahern CA. Engineered transfer RNAs for suppression of premature termination codons. Nat Commun 2019; 10:822. [PMID: 30778053 PMCID: PMC6379413 DOI: 10.1038/s41467-019-08329-4] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Accepted: 12/21/2018] [Indexed: 12/28/2022] Open
Abstract
Premature termination codons (PTCs) are responsible for 10–15% of all inherited disease. PTC suppression during translation offers a promising approach to treat a variety of genetic disorders, yet small molecules that promote PTC read-through have yielded mixed performance in clinical trials. Here we present a high-throughput, cell-based assay to identify anticodon engineered transfer RNAs (ACE-tRNA) which can effectively suppress in-frame PTCs and faithfully encode their cognate amino acid. In total, we identify ACE-tRNA with a high degree of suppression activity targeting the most common human disease-causing nonsense codons. Genome-wide transcriptome ribosome profiling of cells expressing ACE-tRNA at levels which repair PTC indicate that there are limited interactions with translation termination codons. These ACE-tRNAs display high suppression potency in mammalian cells, Xenopus oocytes and mice in vivo, producing PTC repair in multiple genes, including disease causing mutations within cystic fibrosis transmembrane conductance regulator (CFTR). Premature termination codon suppression therapy could be used to treat a range of genetic disorders. Here the authors present a high-throughput cell-based assay to identify anticodon engineered tRNAs with high suppression activity.
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Affiliation(s)
- John D Lueck
- Department of Physiology and Pharmacology, University of Rochester School of Medicine and Dentistry, Rochester, NY, 14642, USA.
| | - Jae Seok Yoon
- CFFT Lab, Cystic Fibrosis Foundation Therapeutics, Lexington, 02421, MA, USA
| | | | - Adam L Mackey
- Department of Molecular Physiology and Biophysics, Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - Daniel T Infield
- Department of Molecular Physiology and Biophysics, Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - Mark A Behlke
- Integrated DNA Technologies Inc., Coralville, IA, 52241, USA
| | - Marshall R Pope
- Department of Molecular Physiology and Biophysics, Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | | | - William R Skach
- CFFT Lab, Cystic Fibrosis Foundation Therapeutics, Lexington, 02421, MA, USA.,Cystic Fibrosis Foundation, Bethesda, 20814, MD, USA
| | - Paul B McCray
- Stead Family Department of Pediatrics, Pappajohn Biomedical Institute, University of Iowa, Iowa City, IA, 52242, USA
| | - Christopher A Ahern
- Department of Molecular Physiology and Biophysics, Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA.
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16
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Dabrowski M, Bukowy-Bieryllo Z, Zietkiewicz E. Advances in therapeutic use of a drug-stimulated translational readthrough of premature termination codons. Mol Med 2018; 24:25. [PMID: 30134808 PMCID: PMC6016875 DOI: 10.1186/s10020-018-0024-7] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 05/01/2018] [Indexed: 12/31/2022] Open
Abstract
Premature termination codons (PTCs) in the coding regions of mRNA lead to the incorrect termination of translation and generation of non-functional, truncated proteins. Translational readthrough of PTCs induced by pharmaceutical compounds is a promising way of restoring functional protein expression and reducing disease symptoms, without affecting the genome or transcriptome of the patient. While in some cases proven effective, the clinical use of readthrough-inducing compounds is still associated with many risks and difficulties. This review focuses on problems directly associated with compounds used to stimulate PTC readthrough, such as their interactions with the cell and organism, their toxicity and bioavailability (cell permeability; tissue deposition etc.). Various strategies designed to overcome these problems are presented.
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Affiliation(s)
- Maciej Dabrowski
- Institute of Human Genetics; Polish Academy of Sciences, Poznan, Poland
| | | | - Ewa Zietkiewicz
- Institute of Human Genetics; Polish Academy of Sciences, Poznan, Poland.
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17
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Mistranslation: from adaptations to applications. Biochim Biophys Acta Gen Subj 2017; 1861:3070-3080. [PMID: 28153753 DOI: 10.1016/j.bbagen.2017.01.031] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 01/23/2017] [Accepted: 01/24/2017] [Indexed: 02/06/2023]
Abstract
BACKGROUND The conservation of the genetic code indicates that there was a single origin, but like all genetic material, the cell's interpretation of the code is subject to evolutionary pressure. Single nucleotide variations in tRNA sequences can modulate codon assignments by altering codon-anticodon pairing or tRNA charging. Either can increase translation errors and even change the code. The frozen accident hypothesis argued that changes to the code would destabilize the proteome and reduce fitness. In studies of model organisms, mistranslation often acts as an adaptive response. These studies reveal evolutionary conserved mechanisms to maintain proteostasis even during high rates of mistranslation. SCOPE OF REVIEW This review discusses the evolutionary basis of altered genetic codes, how mistranslation is identified, and how deviations to the genetic code are exploited. We revisit early discoveries of genetic code deviations and provide examples of adaptive mistranslation events in nature. Lastly, we highlight innovations in synthetic biology to expand the genetic code. MAJOR CONCLUSIONS The genetic code is still evolving. Mistranslation increases proteomic diversity that enables cells to survive stress conditions or suppress a deleterious allele. Genetic code variants have been identified by genome and metagenome sequence analyses, suppressor genetics, and biochemical characterization. GENERAL SIGNIFICANCE Understanding the mechanisms of translation and genetic code deviations enables the design of new codes to produce novel proteins. Engineering the translation machinery and expanding the genetic code to incorporate non-canonical amino acids are valuable tools in synthetic biology that are impacting biomedical research. This article is part of a Special Issue entitled "Biochemistry of Synthetic Biology - Recent Developments" Guest Editor: Dr. Ilka Heinemann and Dr. Patrick O'Donoghue.
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18
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Abstract
Nonsense suppression therapy encompasses approaches aimed at suppressing translation termination at in-frame premature termination codons (PTCs, also known as nonsense mutations) to restore deficient protein function. In this review, we examine the current status of PTC suppression as a therapy for genetic diseases caused by nonsense mutations. We discuss what is currently known about the mechanism of PTC suppression as well as therapeutic approaches under development to suppress PTCs. The approaches considered include readthrough drugs, suppressor tRNAs, PTC pseudouridylation, and inhibition of nonsense-mediated mRNA decay. We also discuss the barriers that currently limit the clinical application of nonsense suppression therapy and suggest how some of these difficulties may be overcome. Finally, we consider how PTC suppression may play a role in the clinical treatment of genetic diseases caused by nonsense mutations.
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Affiliation(s)
- Kim M Keeling
- Department of Microbiology and Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama 35294; , , ,
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19
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Bordeira-Carriço R, Ferreira D, Mateus DD, Pinheiro H, Pêgo AP, Santos MAS, Oliveira C. Rescue of wild-type E-cadherin expression from nonsense-mutated cancer cells by a suppressor-tRNA. Eur J Hum Genet 2014; 22:1085-92. [PMID: 24424122 DOI: 10.1038/ejhg.2013.292] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2013] [Revised: 11/12/2013] [Accepted: 11/20/2013] [Indexed: 02/07/2023] Open
Abstract
Hereditary diffuse gastric cancer (HDGC) syndrome, although rare, is highly penetrant at an early age, and is severe and incurable because of ineffective screening tools and therapy. Approximately 45% of HDGC families carry germline CDH1/E-cadherin alterations, 20% of which are nonsense leading to premature protein truncation. Prophylactic gastrectomy is the only recommended approach for all asymptomatic CDH1 mutation carriers. Suppressor-tRNAs can replace premature stop codons (PTCs) with a cognate amino acid, inducing readthrough and generating full-length proteins. The use of suppressor-tRNAs in HDGC patients could therefore constitute a less invasive therapeutic option for nonsense mutation carriers, delaying the development of gastric cancer. Our analysis revealed that 23/108 (21.3%) of E-cadherin-mutant families carried nonsense mutations that could be potentially corrected by eight suppressor-tRNAs, and arginine was the most frequently affected amino acid. Using site-directed mutagenesis, we developed an arginine suppressor-tRNA vector to correct one HDGC nonsense mutation. E-cadherin- deficient cell lines were transfected with plasmids carrying simultaneously the suppressor-tRNA and wild-type or mutant CDH1 mini-genes. RT-PCR, western blot, immunofluorescence, flow cytometry and proximity ligation assay (PLA) were used to establish the model, and monitor mRNA and protein expression and function recovery from CDH1 vectors. Cells expressing a CDH1 mini-gene, carrying a nonsense mutation and the suppressor-tRNA, recovered full-length E-cadherin expression and its correct localization and incorporation into the adhesion complex. This is the first demonstration of functional recovery of a mutated causative gene in hereditary cancer by cognate amino acid replacement with suppressor-tRNAs. Of the HDGC families, 21.3% are candidates for correction with suppressor-tRNAs to potentially delay cancer onset.
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Affiliation(s)
- Renata Bordeira-Carriço
- Expression Regulation in Cancer Group, Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP), Porto, Portugal
| | - Daniel Ferreira
- Expression Regulation in Cancer Group, Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP), Porto, Portugal
| | - Denisa D Mateus
- Expression Regulation in Cancer Group, Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP), Porto, Portugal
| | - Hugo Pinheiro
- Expression Regulation in Cancer Group, Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP), Porto, Portugal
| | - Ana Paula Pêgo
- 1] INEB, Instituto de Engenharia Biomédica, Universidade do Porto, Porto, Portugal [2] Universidade do Porto-Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Porto, Portugal [3] Universidade do Porto-Faculdade de Engenharia, Porto, Portugal
| | - Manuel A S Santos
- RNA Biology Laboratory, Department of Biology and CESAM, University of Aveiro, Aveiro, Portugal
| | - Carla Oliveira
- 1] Expression Regulation in Cancer Group, Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP), Porto, Portugal [2] Faculty of Medicine of the University of Porto, Porto, Portugal
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20
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Koukuntla R, Ramsey WJ, Young WB, Link CJ. U6 promoter-enhanced GlnUAG suppressor tRNA has higher suppression efficacy and can be stably expressed in 293 cells. J Gene Med 2013; 15:93-101. [PMID: 23303531 DOI: 10.1002/jgm.2696] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2012] [Revised: 11/17/2012] [Accepted: 01/02/2013] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Almost one-third of all human genetic diseases are the result of nonsense mutations that can result in truncated proteins. Nonsense suppressor tRNAs (NSTs) were proposed as valuable tools for gene therapy of genetic diseases caused by premature termination codons (PTCs). Although various strategies have been adapted aiming to increase NST expression and efficacy, low suppression efficacies of NSTs and toxicity associated with stable expression of suppressor tRNAs have hampered the development of NST-mediated gene therapy. METHODS We have employed the U6 promoter to enhance Gln-Amber suppressor tRNA (GlnUAG) expression and to increase PTC suppression in mammalian cells. In an attempt to study the toxic effects of NSTs, a stable 293 cell line constitutively expressing a U6 promoter-enhanced GlnUAG tRNA was established. To examine whether any proteomic changes occurred in cells that constitutively express suppressor tRNA, whole cell proteins from cells with and without any suppressor tRNA expression were analyzed. RESULTS The data obtained suggest that U6 promoter-enhanced GlnUAG tRNAs have higher suppression efficacies than multimers of the same suppressor tRNA without a U6 promoter. Proteomic analysis of cells constitutively expressing the GlnUAG suppressor tRNA indicates that stable expression of NSTs may not lead to significant read through of normal cellular proteins. CONCLUSIONS Because most tRNAs have cell-specific differential expression, this technique will enable the expression of different kinds of suppressor tRNAs in various cell types at high, functionally relevant levels. The techniques developed in the present study may contribute to the further development of suppressor tRNA-mediated gene therapy.
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Affiliation(s)
- Ramesh Koukuntla
- Genetics, Cellular and Developmental Biology, Iowa State University, Ames, IA, USA
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21
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Bordeira-Carriço R, Pêgo AP, Santos M, Oliveira C. Cancer syndromes and therapy by stop-codon readthrough. Trends Mol Med 2012; 18:667-78. [PMID: 23044248 DOI: 10.1016/j.molmed.2012.09.004] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2012] [Revised: 08/10/2012] [Accepted: 09/17/2012] [Indexed: 12/19/2022]
Abstract
Several hereditary cancer syndromes are associated with nonsense mutations that create premature termination codons (PTC). Therapeutic strategies involving readthrough induction partially restore expression of proteins with normal function from nonsense-mutated genes, and small molecules such as aminoglycosides and PTC124 have exhibited promising results for treating patients with cystic fibrosis and Duchenne muscular dystrophy. Transgenic expression of suppressor-tRNAs and depleting translation termination factors are, among others, potential strategies for treating PTC-associated diseases. In this review, the potential of using readthrough strategies as a therapy for cancer syndromes is discussed, and we consider the effect of nonsense-mediated decay and other factors on readthrough efficiency.
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22
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Geslain R, Pan T. Functional analysis of human tRNA isodecoders. J Mol Biol 2009; 396:821-31. [PMID: 20026070 DOI: 10.1016/j.jmb.2009.12.018] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2009] [Revised: 12/02/2009] [Accepted: 12/10/2009] [Indexed: 11/16/2022]
Abstract
tRNA isodecoders share the same anticodon but have differences in their body sequence. An unexpected result from genome sequencing projects is the identification of a large number of tRNA isodecoder genes in mammalian genomes. In the reference human genome, more than 270 isodecoder genes are present among the approximately 450 tRNA genes distributed among 49 isoacceptor families. Whether sequence diversity among isodecoder tRNA genes reflects functional variability is an open question. To address this, we developed a method to quantify the efficiency of tRNA isodecoders in stop-codon suppression in human cell lines. First, a green fluorescent protein (GFP) gene that contains a single UAG stop codon at two distinct locations is introduced. GFP is only produced when a tRNA suppressor containing CUA anticodon is co-transfected with the GFP gene. The suppression efficiency is examined for 31 tRNA isodecoders (all contain CUA anticodon), 21 derived from four isoacceptor families of tRNASer genes, 7 from five families of tRNALeu genes, and 3 from three families of tRNAAla genes. We found that isodecoder tRNAs display a large difference in their suppression efficiency. Among those with above background suppression activity, differences of up to 20-fold were observed. We were able to tune tRNA suppression efficiency by subtly adjusting the tRNA sequence and inter-convert poor suppressors into potent ones. We also demonstrate that isodecoder tRNAs with varying suppression efficiencies have similar stability and exhibit similar levels of aminoacylation in vivo. Our results indicate that naturally occurring tRNA isodecoders can have large functional variations and suggest that some tRNA isodecoders may perform a function distinct from translation.
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Affiliation(s)
- Renaud Geslain
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
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23
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Rederstorff M, Allamand V, Guicheney P, Gartioux C, Richard P, Chaigne D, Krol A, Lescure A. Ex vivo correction of selenoprotein N deficiency in rigid spine muscular dystrophy caused by a mutation in the selenocysteine codon. Nucleic Acids Res 2007; 36:237-44. [PMID: 18025044 PMCID: PMC2248747 DOI: 10.1093/nar/gkm1033] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Premature termination of translation due to nonsense mutations is a frequent cause of inherited diseases. Therefore, many efforts were invested in the development of strategies or compounds to selectively suppress this default. Selenoproteins are interesting candidates considering the idiosyncrasy of the amino acid selenocysteine (Sec) insertion mechanism. Here, we focused our studies on SEPN1, a selenoprotein gene whose mutations entail genetic disorders resulting in different forms of muscular diseases. Selective correction of a nonsense mutation at the Sec codon (UGA to UAA) was undertaken with a corrector tRNASec that was engineered to harbor a compensatory mutation in the anticodon. We demonstrated that its expression restored synthesis of a full-length selenoprotein N both in HeLa cells and in skin fibroblasts from a patient carrying the mutated Sec codon. Readthrough of the UAA codon was effectively dependent on the Sec insertion machinery, therefore being highly selective for this gene and unlikely to generate off-target effects. In addition, we observed that expression of the corrector tRNASec stabilized the mutated SEPN1 transcript that was otherwise more subject to degradation. In conclusion, our data provide interesting evidence that premature termination of translation due to nonsense mutations is amenable to correction, in the context of the specialized selenoprotein synthesis mechanism.
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Affiliation(s)
- M Rederstorff
- Architecture et Réactivité de l'ARN, Université Louis Pasteur de Strasbourg, CNRS, 67084 Strasbourg, France
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24
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Köhrer C, Xie L, Kellerer S, Varshney U, RajBhandary UL. Import of amber and ochre suppressor tRNAs into mammalian cells: a general approach to site-specific insertion of amino acid analogues into proteins. Proc Natl Acad Sci U S A 2001; 98:14310-5. [PMID: 11717406 PMCID: PMC64678 DOI: 10.1073/pnas.251438898] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2001] [Indexed: 11/18/2022] Open
Abstract
A general approach to site-specific insertion of amino acid analogues into proteins in vivo would be the import into cells of a suppressor tRNA aminoacylated with the analogue of choice. The analogue would be inserted at any site in the protein specified by a stop codon in the mRNA. The only requirement is that the suppressor tRNA must not be a substrate for any of the cellular aminoacyl-tRNA synthetases. Here, we describe conditions for the import of amber and ochre suppressor tRNAs derived from Escherichia coli initiator tRNA into mammalian COS1 cells, and we present evidence for their activity in the specific suppression of amber (UAG) and ochre (UAA) codons, respectively. We show that an aminoacylated amber suppressor tRNA (supF) derived from the E. coli tyrosine tRNA can be imported into COS1 cells and acts as a suppressor of amber codons, whereas the same suppressor tRNA imported without prior aminoacylation does not, suggesting that the supF tRNA is not a substrate for any mammalian aminoacyl-tRNA synthetase. These results open the possibility of using the supF tRNA aminoacylated with an amino acid analogue as a general approach for the site-specific insertion of amino acid analogues into proteins in mammalian cells. We discuss the possibility further of importing a mixture of amber and ochre suppressor tRNAs for the insertion of two different amino acid analogues into a protein and the potential use of suppressor tRNA import for treatment of some of the human genetic diseases caused by nonsense mutations.
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Affiliation(s)
- C Köhrer
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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25
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Abstract
This review highlights our current understanding of the biology of, survival of, and transgene expression by genetically modified fibroblasts (GMFb) carrying stably integrated transgenes in vivo. Experimental data demonstrate that three elements will enhance expression by and survival of GMFb in vivo: a matrix scaffolding to take the place of the existing dermis, the presence of elements of the extracellular matrix in the construct used to move GMFb to the in vivo setting, and the utilization of immortalized fibroblasts to carry the transgenes. Although moving GMFb to an in vivo setting is an invasive procedure, there are a number of clinical settings where GMFb appear to be the suitable cell for gene therapy.
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Affiliation(s)
- G G Krueger
- Department of Dermatology, University of Utah Health Sciences Center, Salt Lake City, UT 84132, USA.
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26
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Buvoli M, Buvoli A, Leinwand LA. Suppression of nonsense mutations in cell culture and mice by multimerized suppressor tRNA genes. Mol Cell Biol 2000; 20:3116-24. [PMID: 10757796 PMCID: PMC85606 DOI: 10.1128/mcb.20.9.3116-3124.2000] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We demonstrate here the first experimental suppression of a premature termination codon in vivo by using an ochre suppressor tRNA acting in an intact mouse. Multicopy tRNA expression plasmids were directly injected into skeletal muscle and into the hearts of transgenic mice carrying a reporter gene with an ochre mutation. A strategy for modulation of suppressor efficiency, applicable to diverse systems and based on tandem multimerization of the tRNA gene, is developed. The product of suppression (chloramphenicol acetyltransferase) accumulates linearly with increases in suppressor tRNA concentration to the point where the ochre-suppressing tRNA(Ser) is in four- to fivefold excess over the endogenous tRNA(Ser). The subsequent suppressor activity plateau seems to be attributable to accumulation of unmodified tRNAs. These results define many salient variables for suppression in vivo, for example, for tRNA suppression employed as gene therapy for nonsense defects.
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Affiliation(s)
- M Buvoli
- Department of Molecular Biology, University of Colorado at Boulder, Boulder, Colorado 80309, USA
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