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Lebeda D, Fierenz A, Werfel L, Rosin-Arbesfeld R, Hofhuis J, Thoms S. Systematic and quantitative analysis of stop codon readthrough in Rett syndrome nonsense mutations. J Mol Med (Berl) 2024; 102:641-653. [PMID: 38430393 PMCID: PMC11055764 DOI: 10.1007/s00109-024-02436-6] [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: 10/13/2023] [Revised: 01/16/2024] [Accepted: 02/20/2024] [Indexed: 03/03/2024]
Abstract
Rett syndrome (RTT) is a neurodevelopmental disorder resulting from genetic mutations in the methyl CpG binding protein 2 (MeCP2) gene. Specifically, around 35% of RTT patients harbor premature termination codons (PTCs) within the MeCP2 gene due to nonsense mutations. A promising therapeutic avenue for these individuals involves the use of aminoglycosides, which stimulate translational readthrough (TR) by causing stop codons to be interpreted as sense codons. However, the effectiveness of this treatment depends on several factors, including the type of stop codon and the surrounding nucleotides, collectively referred to as the stop codon context (SCC). Here, we develop a high-content reporter system to precisely measure TR efficiency at different SCCs, assess the recovery of the full-length MeCP2 protein, and evaluate its subcellular localization. We have conducted a comprehensive investigation into the intricate relationship between SCC characteristics and TR induction, examining a total of 14 pathogenic MeCP2 nonsense mutations with the aim to advance the prospects of personalized therapy for individuals with RTT. Our results demonstrate that TR induction can successfully restore full-length MeCP2 protein, albeit to varying degrees, contingent upon the SCC and the specific position of the PTC within the MeCP2 mRNA. TR induction can lead to the re-establishment of nuclear localization of MeCP2, indicating the potential restoration of protein functionality. In summary, our findings underscore the significance of SCC-specific approaches in the development of tailored therapies for RTT. By unraveling the relationship between SCC and TR therapy, we pave the way for personalized, individualized treatment strategies that hold promise for improving the lives of individuals affected by this debilitating neurodevelopmental disorder. KEY MESSAGES: The efficiency of readthrough induction at MeCP2 premature termination codons strongly depends on the stop codon context. The position of the premature termination codon on the transcript influences the readthrough inducibility. A new high-content dual reporter assay facilitates the measurement and prediction of readthrough efficiency of specific nucleotide stop contexts. Readthrough induction results in the recovery of full-length MeCP2 and its re-localization to the nucleus. MeCP2 requires only one of its annotated nuclear localization signals.
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Affiliation(s)
- Dennis Lebeda
- Department for Biochemistry and Molecular Medicine, Medical School EWL, Bielefeld University, Bielefeld, Germany
| | - Adrian Fierenz
- Department of Child and Adolescent Health, University Medical Center Göttingen, Göttingen, Germany
| | - Lina Werfel
- Department of Child and Adolescent Health, University Medical Center Göttingen, Göttingen, Germany
- Present Address: Department of Pediatric Kidney, Liver and Metabolic Diseases, Hannover Medical School, Hannover, Germany
| | - Rina Rosin-Arbesfeld
- Department of Clinical Microbiology and Immunology, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Julia Hofhuis
- Department for Biochemistry and Molecular Medicine, Medical School EWL, Bielefeld University, Bielefeld, Germany
| | - Sven Thoms
- Department for Biochemistry and Molecular Medicine, Medical School EWL, Bielefeld University, Bielefeld, Germany.
- Department of Child and Adolescent Health, University Medical Center Göttingen, Göttingen, Germany.
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Kolakada D, Campbell AE, Galvis LB, Li Z, Lore M, Jagannathan S. A system of reporters for comparative investigation of EJC-independent and EJC-enhanced nonsense-mediated mRNA decay. Nucleic Acids Res 2024; 52:e34. [PMID: 38375914 PMCID: PMC11014337 DOI: 10.1093/nar/gkae121] [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: 06/28/2023] [Revised: 01/05/2024] [Accepted: 02/07/2024] [Indexed: 02/21/2024] Open
Abstract
Nonsense-mediated mRNA decay (NMD) is a network of pathways that degrades transcripts that undergo premature translation termination. In mammals, NMD can be divided into the exon junction complex (EJC)-enhanced and EJC-independent branches. Fluorescence- and luminescence-based reporters have long been effective tools to investigate NMD, yet existing reporters largely focus on the EJC-enhanced pathway. Here, we present a system of reporters for comparative studies of EJC-independent and EJC-enhanced NMD. This system also enables the study of NMD-associated outcomes such as premature termination codon (PTC) readthrough and truncated protein degradation. These reporters are compatible with fluorescence or luminescence-based readouts via transient transfection or stable integration. Using this reporter system, we show that EJC-enhanced NMD RNA levels are reduced by 2- or 9-fold and protein levels are reduced by 7- or 12-fold compared to EJC-independent NMD, depending on the reporter gene used. Additionally, the extent of readthrough induced by G418 and an NMD inhibitor (SMG1i), alone and in combination, varies across NMD substrates. When combined, G418 and SMG1i increase readthrough product levels in an additive manner for EJC-independent reporters, while EJC-enhanced reporters show a synergistic effect. We present these reporters as a valuable toolkit to deepen our understanding of NMD and its associated mechanisms.
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Affiliation(s)
- Divya Kolakada
- Molecular Biology Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Amy E Campbell
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Laura Baquero Galvis
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Zhongyou Li
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Mlana Lore
- Molecular Biology Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Sujatha Jagannathan
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
- RNA Bioscience Initiative, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
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Khandia R, Gurjar P, Kamal MA, Greig NH. Relative synonymous codon usage and codon pair analysis of depression associated genes. Sci Rep 2024; 14:3502. [PMID: 38346990 PMCID: PMC10861588 DOI: 10.1038/s41598-024-51909-8] [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: 09/06/2023] [Accepted: 01/11/2024] [Indexed: 02/15/2024] Open
Abstract
Depression negatively impacts mood, behavior, and mental and physical health. It is the third leading cause of suicides worldwide and leads to decreased quality of life. We examined 18 genes available at the genetic testing registry (GTR) from the National Center for Biotechnological Information to investigate molecular patterns present in depression-associated genes. Different genotypes and differential expression of the genes are responsible for ensuing depression. The present study, investigated codon pattern analysis, which might play imperative roles in modulating gene expression of depression-associated genes. Of the 18 genes, seven and two genes tended to up- and down-regulate, respectively, and, for the remaining genes, different genotypes, an outcome of SNPs were responsible alone or in combination with differential expression for different conditions associated with depression. Codon context analysis revealed the abundance of identical GTG-GTG and CTG-CTG pairs, and the rarity of methionine-initiated codon pairs. Information based on codon usage, preferred codons, rare, and codon context might be used in constructing a deliverable synthetic construct to correct the gene expression level of the human body, which is altered in the depressive state. Other molecular signatures also revealed the role of evolutionary forces in shaping codon usage.
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Affiliation(s)
- Rekha Khandia
- Department of Biochemistry and Genetics, Barkatullah University, Bhopal, 462026, MP, India.
| | - Pankaj Gurjar
- Centre for Global Health Research, Saveetha Medical College and Hospital, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai, Tamilnadu, India
- Department of Science and Engineering, Novel Global Community Educational Foundation, Hebersham, NSW, Australia
| | - Mohammad Amjad Kamal
- Joint Laboratory of Artificial Intelligence in Healthcare, Institutes for Systems Genetics and West China School of Nursing, Frontiers Science Center for Disease-related Molecular Network, West China Hospital, Sichuan University, Chengdu, China
- King Fahd Medical Research Center, King Abdulaziz University, Jeddah, 21589, Saudi Arabia
- Department of Pharmacy, Faculty of Allied Health Sciences, Daffodil International University, Dhaka, 1207, Bangladesh
- Enzymoics, Novel Global Community Educational Foundation, 7 Peterlee place, Hebersham, NSW, 2770, Australia
| | - Nigel H Greig
- Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA.
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Khandia R, Gurjar P, Romashchenko V, Al-Hussain SA, Alexiou A, Zouganelis G, Zaki MEA. In-silico Codon Context and Synonymous Usage Analysis of Genes for Molecular Mechanisms Inducing Autophagy and Apoptosis with Reference to Neurodegenerative Disorders. J Alzheimers Dis 2024; 99:927-939. [PMID: 38728191 DOI: 10.3233/jad-240158] [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] [Indexed: 05/12/2024]
Abstract
Background Autophagy and apoptosis are cellular processes that maintain cellular homeostasis and remove damaged or aged organelles or aggregated and misfolded proteins. Stress factors initiate the signaling pathways common to autophagy and apoptosis. An imbalance in the autophagy and apoptosis, led by cascade of molecular mechanism prior to both processes culminate into neurodegeneration. Objective In present study, we urge to investigate the codon usage pattern of genes which are common before initiating autophagy and apoptosis. Methods In the present study, we took up eleven genes (DAPK1, BECN1, PIK3C3 (VPS34), BCL2, MAPK8, BNIP3 L (NIX), PMAIP1, BAD, BID, BBC3, MCL1) that are part of molecular signaling mechanism prior to autophagy and apoptosis. We analyzed dinucleotide odds ratio, codon bias, usage, context, and rare codon analysis. Results CpC and GpG dinucleotides were abundant, with the dominance of G/C ending codons as preferred codons. Clustering analysis revealed that MAPK8 had a distinct codon usage pattern compared to other envisaged genes. Both positive and negative contexts were observed, and GAG-GAG followed by CTG-GCC was the most abundant codon pair. Of the six synonymous arginine codons, two codons CGT and CGA were the rarest. Conclusions The information presented in the study may be used to manipulate the process of autophagy and apoptosis and to check the pathophysiology associated with their dysregulation.
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Affiliation(s)
- Rekha Khandia
- Department of Biochemistry and Genetics, Barkatullah University, Bhopal, India
| | - Pankaj Gurjar
- Centre for Global Health Research, Saveetha Medical College and Hospital, Saveetha Institute of Medical and Technical Sciences, Chennai, Tamil Nadu, India
- Department of Science and Engineering, Novel Global Community Educational Foundation, NSW, Australia
| | | | - Sami A Al-Hussain
- Department of Chemistry, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh, Saudi Arabia
| | - Athanasios Alexiou
- Department of Science and Engineering, Novel Global Community Educational Foundation, NSW, Australia
- University Centre for Research & Development, Chandigarh University, Chandigarh-Ludhiana Highway, Mohali, Punjab, India
- Department of Research & Development, Funogen, Athens, Greece
- Department of Research & Development, AFNP Med, Wienna, Austria
| | - George Zouganelis
- School of Human Sciences, College of Life and Natural Sciences, University of Derby, Kedleston Road, Derby, UK
| | - Magdi E A Zaki
- Department of Chemistry, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh, Saudi Arabia
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Kolakada D, Campbell AE, Baquero Galvis L, Li Z, Lore M, Jagannathan S. A system of reporters for comparative investigation of EJC-independent and EJC-enhanced nonsense-mediated mRNA decay. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.14.567061. [PMID: 38014198 PMCID: PMC10680754 DOI: 10.1101/2023.11.14.567061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Nonsense-mediated mRNA decay (NMD) is a network of pathways that degrades transcripts that undergo premature translation termination. In mammals, NMD can be divided into the exon junction complex (EJC)-enhanced and EJC-independent branches. Fluorescence- and luminescence-based reporters have long been effective tools to investigate NMD, yet existing reporters largely focus on the EJC-enhanced pathway. Here, we present a system of reporters for comparative studies of EJC-independent and EJC-enhanced NMD. This system also enables the study of NMD-associated outcomes such as premature termination codon (PTC) readthrough and truncated protein degradation. These reporters are compatible with fluorescence or luminescence-based readouts via transient transfection or stable integration. Using this reporter system, we show that EJC-enhanced NMD RNA levels are reduced by 2- or 9-fold and protein levels are reduced by 7- or 12-fold compared to EJC-independent NMD, depending on the reporter gene used. Additionally, the extent of readthrough induced by G418 and SMG1i, alone and in combination, varies across NMD substrates. When combined, G418 and SMG1i increase readthrough product levels in an additive manner for EJC-independent reporters, while EJC-enhanced reporters show a synergistic effect. We present these reporters as a valuable toolkit to deepen our understanding of NMD and its associated mechanisms.
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Affiliation(s)
- Divya Kolakada
- Molecular Biology Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Amy E. Campbell
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Laura Baquero Galvis
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Zhongyou Li
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Mlana Lore
- Molecular Biology Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Sujatha Jagannathan
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
- RNA Bioscience Initiative, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
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Anastassiadis T, Köhrer C. Ushering in the era of tRNA medicines. J Biol Chem 2023; 299:105246. [PMID: 37703991 PMCID: PMC10583094 DOI: 10.1016/j.jbc.2023.105246] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Revised: 09/03/2023] [Accepted: 09/06/2023] [Indexed: 09/15/2023] Open
Abstract
Long viewed as an intermediary in protein translation, there is a growing awareness that tRNAs are capable of myriad other biological functions linked to human health and disease. These emerging roles could be tapped to leverage tRNAs as diagnostic biomarkers, therapeutic targets, or even as novel medicines. Furthermore, the growing array of tRNA-derived fragments, which modulate an increasingly broad spectrum of cellular pathways, is expanding this opportunity. Together, these molecules offer drug developers the chance to modulate the impact of mutations and to alter cell homeostasis. Moreover, because a single therapeutic tRNA can facilitate readthrough of a genetic mutation shared across multiple genes, such medicines afford the opportunity to define patient populations not based on their clinical presentation or mutated gene but rather on the mutation itself. This approach could potentially transform the treatment of patients with rare and ultrarare diseases. In this review, we explore the diverse biology of tRNA and its fragments, examining the past and present challenges to provide a comprehensive understanding of the molecules and their therapeutic potential.
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7
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Trexler M, Bányai L, Kerekes K, Patthy L. Evolution of termination codons of proteins and the TAG-TGA paradox. Sci Rep 2023; 13:14294. [PMID: 37653005 PMCID: PMC10471768 DOI: 10.1038/s41598-023-41410-z] [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: 04/17/2023] [Accepted: 08/25/2023] [Indexed: 09/02/2023] Open
Abstract
In most eukaryotes and prokaryotes TGA is used at a significantly higher frequency than TAG as termination codon of protein-coding genes. Although this phenomenon has been recognized several years ago, there is no generally accepted explanation for the TAG-TGA paradox. Our analyses of human mutation data revealed that out of the eighteen sense codons that can give rise to a nonsense codon by single base substitution, the CGA codon is exceptional: it gives rise to the TGA stop codon at an order of magnitude higher rate than the other codons. Here we propose that the TAG-TGA paradox is due to methylation and hypermutabilty of CpG dinucleotides. In harmony with this explanation, we show that the coding genomes of organisms with strong CpG methylation have a significant bias for TGA whereas those from organisms that lack CpG methylation use TGA and TAG termination codons with similar probability.
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Affiliation(s)
- Mária Trexler
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, 1117, Hungary
| | - László Bányai
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, 1117, Hungary
| | - Krisztina Kerekes
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, 1117, Hungary
| | - László Patthy
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, 1117, Hungary.
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Li S, Li J, Shi W, Nie Z, Zhang S, Ma F, Hu J, Chen J, Li P, Xie X. Pharmaceuticals Promoting Premature Termination Codon Readthrough: Progress in Development. Biomolecules 2023; 13:988. [PMID: 37371567 DOI: 10.3390/biom13060988] [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: 04/25/2023] [Revised: 05/27/2023] [Accepted: 06/06/2023] [Indexed: 06/29/2023] Open
Abstract
Around 11% of all known gene lesions causing human genetic diseases are nonsense mutations that introduce a premature stop codon (PTC) into the protein-coding gene sequence. Drug-induced PTC readthrough is a promising therapeutic strategy for treating hereditary diseases caused by nonsense mutations. To date, it has been found that more than 50 small-molecular compounds can promote PTC readthrough, known as translational readthrough-inducing drugs (TRIDs), and can be divided into two major categories: aminoglycosides and non-aminoglycosides. This review summarizes the pharmacodynamics and clinical application potential of the main TRIDs discovered so far, especially some newly discovered TRIDs in the past decade. The discovery of these TRIDs brings hope for treating nonsense mutations in various genetic diseases. Further research is still needed to deeply understand the mechanism of eukaryotic cell termination and drug-induced PTC readthrough so that patients can achieve the greatest benefit from the various TRID treatments.
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Affiliation(s)
- Shan Li
- School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China
| | - Juan Li
- Central Laboratory, The First Hospital of Lanzhou University, Lanzhou 730000, China
- Gansu Key Laboratory of Genetic Study of Hematopathy, The First Hospital of Lanzhou University, Lanzhou 730000, China
| | - Wenjing Shi
- School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China
| | - Ziyan Nie
- School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China
| | - Shasha Zhang
- School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China
| | - Fengdie Ma
- School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China
| | - Jun Hu
- School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China
| | - Jianjun Chen
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China
| | - Peiqiang Li
- School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China
| | - Xiaodong Xie
- School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China
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Wagner RN, Wießner M, Friedrich A, Zandanell J, Breitenbach-Koller H, Bauer JW. Emerging Personalized Opportunities for Enhancing Translational Readthrough in Rare Genetic Diseases and Beyond. Int J Mol Sci 2023; 24:6101. [PMID: 37047074 PMCID: PMC10093890 DOI: 10.3390/ijms24076101] [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: 02/16/2023] [Revised: 03/17/2023] [Accepted: 03/21/2023] [Indexed: 04/14/2023] Open
Abstract
Nonsense mutations trigger premature translation termination and often give rise to prevalent and rare genetic diseases. Consequently, the pharmacological suppression of an unscheduled stop codon represents an attractive treatment option and is of high clinical relevance. At the molecular level, the ability of the ribosome to continue translation past a stop codon is designated stop codon readthrough (SCR). SCR of disease-causing premature termination codons (PTCs) is minimal but small molecule interventions, such as treatment with aminoglycoside antibiotics, can enhance its frequency. In this review, we summarize the current understanding of translation termination (both at PTCs and at cognate stop codons) and highlight recently discovered pathways that influence its fidelity. We describe the mechanisms involved in the recognition and readthrough of PTCs and report on SCR-inducing compounds currently explored in preclinical research and clinical trials. We conclude by reviewing the ongoing attempts of personalized nonsense suppression therapy in different disease contexts, including the genetic skin condition epidermolysis bullosa.
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Affiliation(s)
- Roland N. Wagner
- Department of Dermatology and Allergology, University Hospital of the Paracelsus Medical University, 5020 Salzburg, Austria
| | - Michael Wießner
- Department of Dermatology and Allergology, University Hospital of the Paracelsus Medical University, 5020 Salzburg, Austria
| | - Andreas Friedrich
- Department of Dermatology and Allergology, University Hospital of the Paracelsus Medical University, 5020 Salzburg, Austria
- Department of Biosciences, University of Salzburg, 5020 Salzburg, Austria
| | - Johanna Zandanell
- Department of Dermatology and Allergology, University Hospital of the Paracelsus Medical University, 5020 Salzburg, Austria
| | | | - Johann W. Bauer
- Department of Dermatology and Allergology, University Hospital of the Paracelsus Medical University, 5020 Salzburg, Austria
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Recoding of Nonsense Mutation as a Pharmacological Strategy. Biomedicines 2023; 11:biomedicines11030659. [PMID: 36979640 PMCID: PMC10044939 DOI: 10.3390/biomedicines11030659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 02/18/2023] [Accepted: 02/20/2023] [Indexed: 02/24/2023] Open
Abstract
Approximately 11% of genetic human diseases are caused by nonsense mutations that introduce a premature termination codon (PTC) into the coding sequence. The PTC results in the production of a potentially harmful shortened polypeptide and activation of a nonsense-mediated decay (NMD) pathway. The NMD pathway reduces the burden of unproductive protein synthesis by lowering the level of PTC mRNA. There is an endogenous rescue mechanism that produces a full-length protein from a PTC mRNA. Nonsense suppression therapies aim to increase readthrough, suppress NMD, or are a combination of both strategies. Therefore, treatment with translational readthrough-inducing drugs (TRIDs) and NMD inhibitors may increase the effectiveness of PTC suppression. Here we discuss the mechanism of PTC readthrough and the development of novel approaches to PTC suppression. We also discuss the toxicity and bioavailability of therapeutics used to stimulate PTC readthrough.
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Evaluation of Pharmacological Rescue of Melanocortin-4 Receptor Nonsense Mutations by Aminoglycoside. Life (Basel) 2022; 12:life12111793. [PMID: 36362948 PMCID: PMC9697516 DOI: 10.3390/life12111793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 10/18/2022] [Accepted: 11/02/2022] [Indexed: 11/09/2022] Open
Abstract
The melanocortin-4 receptor (MC4R) is critical for central satiety regulation, therefore presenting a potent target for pharmacological obesity treatment. Melanocortin-4 receptor mutations prevalently cause monogenetic obesity. A possibility of overcoming stop mutations is aminoglycoside-mediated translational readthrough. Promising results were achieved in COS-7 cells, but data for human cell systems are still missing, so uncertainty surrounds this potential treatment. In transfected HEK-293 cells, we tested whether translational readthrough by aminoglycoside Geneticin combined with high-affinity ligand setmelanotide, which is effective in proopiomelanocortin or leptin receptor deficiency patients, is a treatment option for affected patients. Five MC4R nonsense mutants (W16X, Y35X_D37V, E61X, W258X, Q307X) were investigated. Confocal microscopy and cell surface expression assays revealed the importance of the mutations’ position within the MC4R. N-terminal mutants were marginally expressed independent of Geneticin treatment, whereas mutants with nonsense mutations in transmembrane helix 6 or helix 8 showed wild-type-like expression. For functional analysis, Gs and Gq/11 signaling were measured. N-terminal mutants (W16X, Y35X_D37V) showed no cAMP formation after challenge with alpha-MSH or setmelanotide, irrespective of Geneticin treatment. Similarly, Gs activation was almost impossible in W258X and Q307X with wild-type-like cell surface expression. Results for Gq/11 signaling were comparable. Based on our data, this approach improbably represents a therapeutic option.
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Lombardi S, Testa MF, Pinotti M, Branchini A. Translation termination codons in protein synthesis and disease. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2022; 132:1-48. [PMID: 36088072 DOI: 10.1016/bs.apcsb.2022.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Fidelity of protein synthesis, a process shaped by several mechanisms involving specialized ribosome regions and external factors, ensures the precise reading of sense as well as stop codons (UGA, UAG, UAA), which are usually localized at the 3' of mRNA and drive the release of the polypeptide chain. However, either natural (NTCs) or premature (PTCs) termination codons, the latter arising from nucleotide changes, can undergo a recoding process named ribosome or translational readthrough, which insert specific amino acids (NTCs) or subset(s) depending on the stop codon type (PTCs). This process is particularly relevant for nonsense mutations, a relatively frequent cause of genetic disorders, which impair gene expression at different levels by potentially leading to mRNA degradation and/or synthesis of truncated proteins. As a matter of fact, many efforts have been made to develop efficient and safe readthrough-inducing compounds, which have been challenged in several models of human disease to provide with a therapy. In this view, the dissection of the molecular determinants shaping the outcome of readthrough, namely nucleotide and protein contexts as well as their interplay and impact on protein structure/function, is crucial to identify responsive nonsense mutations resulting in functional full-length proteins. The interpretation of experimental and mechanistic findings is also important to define a possibly clear picture of potential readthrough-favorable features useful to achieve rescue profiles compatible with therapeutic thresholds typical of each targeted disorder, which is of primary importance for the potential translatability of readthrough into a personalized and mutation-specific, and thus patient-oriented, therapeutic strategy.
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Affiliation(s)
- Silvia Lombardi
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
| | - Maria Francesca Testa
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Mirko Pinotti
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Alessio Branchini
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy.
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