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Screening Readthrough Compounds to Suppress Nonsense Mutations: Possible Application to β-Thalassemia. J Clin Med 2020; 9:jcm9020289. [PMID: 31972957 PMCID: PMC7073686 DOI: 10.3390/jcm9020289] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 01/08/2020] [Accepted: 01/13/2020] [Indexed: 02/07/2023] Open
Abstract
Several types of thalassemia (including β039-thalassemia) are caused by nonsense mutations in genes controlling globin production, leading to premature translation termination and mRNA destabilization mediated by the nonsense mediated mRNA decay. Drugs (for instance, aminoglycosides) can be designed to suppress premature translation termination by inducing readthrough (or nonsense suppression) at the premature termination codon. These findings have introduced new hopes for the development of a pharmacologic approach to cure this genetic disease. In the present review, we first summarize the principle and current status of the chemical relief for the expression of functional proteins from genes otherwise unfruitful for the presence of nonsense mutations. Second, we compare data available on readthrough molecules for β0-thalassemia. The examples reported in the review strongly suggest that ribosomal readthrough should be considered as a therapeutic approach for the treatment of β0-thalassemia caused by nonsense mutations. Concluding, the discovery of molecules, exhibiting the property of inducing β-globin, such as readthrough compounds, is of great interest and represents a hope for several patients, whose survival will depend on the possible use of drugs rendering blood transfusion and chelation therapy unnecessary.
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Ataluren for the Treatment of Usher Syndrome 2A Caused by Nonsense Mutations. Int J Mol Sci 2019; 20:ijms20246274. [PMID: 31842393 PMCID: PMC6940777 DOI: 10.3390/ijms20246274] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 12/05/2019] [Accepted: 12/10/2019] [Indexed: 12/18/2022] Open
Abstract
The identification of genetic defects that underlie inherited retinal diseases (IRDs) paves the way for the development of therapeutic strategies. Nonsense mutations caused approximately 12% of all IRD cases, resulting in a premature termination codon (PTC). Therefore, an approach that targets nonsense mutations could be a promising pharmacogenetic strategy for the treatment of IRDs. Small molecules (translational read-through inducing drugs; TRIDs) have the potential to mediate the read-through of nonsense mutations by inducing expression of the full-length protein. We provide novel data on the read-through efficacy of Ataluren on a nonsense mutation in the Usher syndrome gene USH2A that causes deaf-blindness in humans. We demonstrate Ataluren´s efficacy in both transiently USH2AG3142*-transfected HEK293T cells and patient-derived fibroblasts by restoring USH2A protein expression. Furthermore, we observed enhanced ciliogenesis in patient-derived fibroblasts after treatment with TRIDs, thereby restoring a phenotype that is similar to that found in healthy donors. In light of recent findings, we validated Ataluren´s efficacy to induce read-through on a nonsense mutation in USH2A-related IRD. In line with published data, our findings support the use of patient-derived fibroblasts as a platform for the validation of preclinical therapies. The excellent biocompatibility combined with sustained read-through efficacy makes Ataluren an ideal TRID for treating nonsense mutations based IRDs.
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Cehajic Kapetanovic J, Barnard AR, MacLaren RE. Molecular Therapies for Choroideremia. Genes (Basel) 2019; 10:genes10100738. [PMID: 31548516 PMCID: PMC6826983 DOI: 10.3390/genes10100738] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 09/14/2019] [Accepted: 09/20/2019] [Indexed: 01/03/2023] Open
Abstract
Advances in molecular research have culminated in the development of novel gene-based therapies for inherited retinal diseases. We have recently witnessed several groundbreaking clinical studies that ultimately led to approval of Luxturna, the first gene therapy for an inherited retinal disease. In parallel, international research community has been engaged in conducting gene therapy trials for another more common inherited retinal disease known as choroideremia and with phase III clinical trials now underway, approval of this therapy is poised to follow suit. This chapter discusses new insights into clinical phenotyping and molecular genetic testing in choroideremia with review of molecular mechanisms implicated in its pathogenesis. We provide an update on current gene therapy trials and discuss potential inclusion of female carries in future clinical studies. Alternative molecular therapies are discussed including suitability of CRISPR gene editing, small molecule nonsense suppression therapy and vision restoration strategies in late stage choroideremia.
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Affiliation(s)
- Jasmina Cehajic Kapetanovic
- Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford OX3 9DU, UK; (A.R.B.); (R.E.M.)
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
- Correspondence:
| | - Alun R. Barnard
- Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford OX3 9DU, UK; (A.R.B.); (R.E.M.)
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
| | - Robert E. MacLaren
- Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford OX3 9DU, UK; (A.R.B.); (R.E.M.)
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
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54
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Vázquez-Domínguez I, Garanto A, Collin RWJ. Molecular Therapies for Inherited Retinal Diseases-Current Standing, Opportunities and Challenges. Genes (Basel) 2019; 10:genes10090654. [PMID: 31466352 PMCID: PMC6770110 DOI: 10.3390/genes10090654] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 08/23/2019] [Accepted: 08/26/2019] [Indexed: 12/15/2022] Open
Abstract
Inherited retinal diseases (IRDs) are both genetically and clinically highly heterogeneous and have long been considered incurable. Following the successful development of a gene augmentation therapy for biallelic RPE65-associated IRD, this view has changed. As a result, many different therapeutic approaches are currently being developed, in particular a large variety of molecular therapies. These are depending on the severity of the retinal degeneration, knowledge of the pathophysiological mechanism underlying each subtype of IRD, and the therapeutic target molecule. DNA therapies include approaches such as gene augmentation therapy, genome editing and optogenetics. For some genetic subtypes of IRD, RNA therapies and compound therapies have also shown considerable therapeutic potential. In this review, we summarize the current state-of-the-art of various therapeutic approaches, including the pros and cons of each strategy, and outline the future challenges that lie ahead in the combat against IRDs.
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Affiliation(s)
- Irene Vázquez-Domínguez
- Department of Human Genetics and Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525GA Nijmegen, The Netherlands
| | - Alejandro Garanto
- Department of Human Genetics and Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525GA Nijmegen, The Netherlands.
| | - Rob W J Collin
- Department of Human Genetics and Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525GA Nijmegen, The Netherlands.
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Kretschmer V, Patnaik SR, Kretschmer F, Chawda MM, Hernandez-Hernandez V, May-Simera HL. Progressive Characterization of Visual Phenotype in Bardet-Biedl Syndrome Mutant Mice. Invest Ophthalmol Vis Sci 2019; 60:1132-1143. [PMID: 30901771 DOI: 10.1167/iovs.18-25210] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Bardet-Biedl syndrome (BBS) is an archetypical ciliopathy caused by defective ciliary trafficking and consequent function. Insights gained from BBS mouse models are applicable to other syndromic and nonsyndromic retinal diseases. This progressive characterization of the visual phenotype in three BBS mouse models sets a baseline for testing therapeutic interventions. Methods Longitudinal acquisition of electroretinograms, optical coherence tomography scans, and visual acuity using the optomotor reflex in Bbs6/Mkks, Bbs8/Ttc8, and Bbs5 knockout mice. Gene and protein expression analysis in vivo and in vitro. Results Complete loss of BBS5, BBS6, or BBS8 leads to different rates of retinal degeneration and visual function over time. BBS8-deficient mice showed the fastest rate of degeneration, and BBS8 seems to be required for cone photoreceptors to reach functional maturity. In contrast, the loss of BBS5 (a further BBSome component) showed very little degeneration. Loss of BBS8 versus BBS5 resulted in different physiologic responses both in vivo and in vitro. BBS6-deficient mice show a slower rate of degeneration with both rod and cone function reducing at a similar rate. Conclusions The mouse models analyzed show distinct and diverging courses of degeneration upon loss of BBS5, BBS6, or BBS8, which can be used as a benchmark to test therapeutic interventions. Close consideration of the different phenotypes reveal subtle but important differences relating to their function. Because we also see differences in terms of phenotype depending on the type of visual assessment used, our data highlight the importance of using a combinatorial approach for assessment of visual function.
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Affiliation(s)
- Viola Kretschmer
- Cilia Cell Biology, Institute of Molecular Physiology, Johannes Gutenberg University, Mainz, Germany
| | - Sarita Rani Patnaik
- Cilia Cell Biology, Institute of Molecular Physiology, Johannes Gutenberg University, Mainz, Germany
| | - Friedrich Kretschmer
- Scientific Computing Facility, Max Planck Institute for Brain Research, Frankfurt, Germany
| | - Mira Manilal Chawda
- Genetics and Genomic Medicine Programme, Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
| | - Victor Hernandez-Hernandez
- Genetics and Genomic Medicine Programme, Great Ormond Street Institute of Child Health, University College London, London, United Kingdom.,Department of Life Sciences, College of Health and Life Sciences, Brunel University London, London, United Kingdom
| | - Helen Louise May-Simera
- Cilia Cell Biology, Institute of Molecular Physiology, Johannes Gutenberg University, Mainz, Germany
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Campofelice A, Lentini L, Di Leonardo A, Melfi R, Tutone M, Pace A, Pibiri I. Strategies against Nonsense: Oxadiazoles as Translational Readthrough-Inducing Drugs (TRIDs). Int J Mol Sci 2019; 20:ijms20133329. [PMID: 31284579 PMCID: PMC6651739 DOI: 10.3390/ijms20133329] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 07/01/2019] [Accepted: 07/02/2019] [Indexed: 12/24/2022] Open
Abstract
This review focuses on the use of oxadiazoles as translational readthrough-inducing drugs (TRIDs) to rescue the functional full-length protein expression in mendelian genetic diseases caused by nonsense mutations. These mutations in specific genes generate premature termination codons (PTCs) responsible for the translation of truncated proteins. After a brief introduction on nonsense mutations and their pathological effects, the features of various classes of TRIDs will be described discussing differences or similarities in their mechanisms of action. Strategies to correct the PTCs will be presented, particularly focusing on a new class of Ataluren-like oxadiazole derivatives in comparison to aminoglycosides. Additionally, recent results on the efficiency of new candidate TRIDs in restoring the production of the cystic fibrosis transmembrane regulator (CFTR) protein will be presented. Finally, a prospectus on complementary strategies to enhance the effect of TRIDs will be illustrated together with a conclusive paragraph about perspectives, opportunities, and caveats in developing small molecules as TRIDs.
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Affiliation(s)
- Ambra Campofelice
- Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche (STEBICEF), Università Degli Studi di Palermo, Viale delle Scienze Ed. 16-17, 90128 Palermo, Italy
| | - Laura Lentini
- Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche (STEBICEF), Università Degli Studi di Palermo, Viale delle Scienze Ed. 16-17, 90128 Palermo, Italy
| | - Aldo Di Leonardo
- Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche (STEBICEF), Università Degli Studi di Palermo, Viale delle Scienze Ed. 16-17, 90128 Palermo, Italy
| | - Raffaella Melfi
- Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche (STEBICEF), Università Degli Studi di Palermo, Viale delle Scienze Ed. 16-17, 90128 Palermo, Italy
| | - Marco Tutone
- Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche (STEBICEF), Università Degli Studi di Palermo, Viale delle Scienze Ed. 16-17, 90128 Palermo, Italy
| | - Andrea Pace
- Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche (STEBICEF), Università Degli Studi di Palermo, Viale delle Scienze Ed. 16-17, 90128 Palermo, Italy
| | - Ivana Pibiri
- Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche (STEBICEF), Università Degli Studi di Palermo, Viale delle Scienze Ed. 16-17, 90128 Palermo, Italy.
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Balestra D, Branchini A. Molecular Mechanisms and Determinants of Innovative Correction Approaches in Coagulation Factor Deficiencies. Int J Mol Sci 2019; 20:ijms20123036. [PMID: 31234407 PMCID: PMC6627357 DOI: 10.3390/ijms20123036] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 06/07/2019] [Accepted: 06/18/2019] [Indexed: 02/07/2023] Open
Abstract
Molecular strategies tailored to promote/correct the expression and/or processing of defective coagulation factors would represent innovative therapeutic approaches beyond standard substitutive therapy. Here, we focus on the molecular mechanisms and determinants underlying innovative approaches acting at DNA, mRNA and protein levels in inherited coagulation factor deficiencies, and in particular on: (i) gene editing approaches, which have permitted intervention at the DNA level through the specific recognition, cleavage, repair/correction or activation of target sequences, even in mutated gene contexts; (ii) the rescue of altered pre-mRNA processing through the engineering of key spliceosome components able to promote correct exon recognition and, in turn, the synthesis and secretion of functional factors, as well as the effects on the splicing of missense changes affecting exonic splicing elements; this section includes antisense oligonucleotide- or siRNA-mediated approaches to down-regulate target genes; (iii) the rescue of protein synthesis/function through the induction of ribosome readthrough targeting nonsense variants or the correction of folding defects caused by amino acid substitutions. Overall, these approaches have shown the ability to rescue the expression and/or function of potentially therapeutic levels of coagulation factors in different disease models, thus supporting further studies in the future aimed at evaluating the clinical translatability of these new strategies.
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Affiliation(s)
- Dario Balestra
- Department of Life Sciences and Biotechnology, University of Ferrara, 44121 Ferrara, Italy.
| | - Alessio Branchini
- Department of Life Sciences and Biotechnology, University of Ferrara, 44121 Ferrara, Italy.
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2-Aminothiazole-4-carboxamides Enhance Readthrough of Premature Termination Codons by Aminoglycosides. ACS Med Chem Lett 2019; 10:726-731. [PMID: 31097990 DOI: 10.1021/acsmedchemlett.8b00610] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 04/09/2019] [Indexed: 02/06/2023] Open
Abstract
Nonsense mutations introduce a premature termination codon (PTC) and are the underlying cause of multiple rare genetic diseases and cancers. Although certain aminoglycosides bind to eukaryotic ribosomes enabling incorporation of an amino acid at the PTC and formation of full-length protein, they are inefficient and toxic at therapeutic doses. Library screening in assays that measure readthrough at a PTC in the TP53 gene in human HDQ-P1 cells identified six novel 2-aminothiazole-4-carboxamide derivatives that potentiate the PTC readthrough (PTCR) efficiency of G418 when used in combination. The two most potent compounds incorporated a 4-indazole motif on the 2-aminothiazole nitrogen and a hydrophobic aryl substituent on the carboxamide nitrogen. These compounds are valuable tools to further investigate the therapeutic potential of aminoglycoside-induced PTCR.
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59
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Huang L, Aghajan M, Quesenberry T, Low A, Murray SF, Monia BP, Guo S. Targeting Translation Termination Machinery with Antisense Oligonucleotides for Diseases Caused by Nonsense Mutations. Nucleic Acid Ther 2019; 29:175-186. [PMID: 31070517 PMCID: PMC6686700 DOI: 10.1089/nat.2019.0779] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Efforts to develop treatments for diseases caused by nonsense mutations have focused on identification of small molecules that promote translational read-through of messenger RNAs (mRNAs) harboring nonsense stop codons to produce full-length proteins. However, to date, no small molecule read-through drug has received FDA approval, probably because of a lack of balance between efficacy and safety. Depletion of translation termination factors eukaryotic release factor (eRF) 1 and eRF3a in cells was shown to promote translational read-through of a luciferase reporter gene harboring a nonsense mutation. In this study, we identified antisense oligonucleotides (ASOs) targeting translation termination factors and determined if ASO-mediated depletion of these factors could be a potentially effective and safe therapeutic approach for diseases caused by nonsense mutations. We found that ASO-mediated reduction of either eRF1 or eRF3a to 30%–40% of normal levels in the mouse liver is well tolerated. Hemophilia mice that express a mutant allele of human coagulation factor IX (FIX) containing nonsense mutation R338X were treated with eRF1- or eRF3a-ASO. We found that although eRF1- or eRF3a-ASO alone only elicited a moderate read-through effect on hFIX-R338X mRNA, both worked in synergy with geneticin, a small molecule read-through drug, demonstrating significantly increased production of functional full-length hFIX protein to levels that would rescue disease phenotypes in these mice. Overall our results indicate that modulating the translation termination pathway in the liver by ASOs may provide a novel approach to improving the efficacy of small molecule read-through drugs to treat human genetic diseases caused by nonsense mutations.
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Affiliation(s)
- Lulu Huang
- Ionis Pharmaceuticals, Carlsbad, California
| | | | | | - Audrey Low
- Ionis Pharmaceuticals, Carlsbad, California
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Treating Rett syndrome: from mouse models to human therapies. Mamm Genome 2019; 30:90-110. [PMID: 30820643 PMCID: PMC6606665 DOI: 10.1007/s00335-019-09793-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 02/09/2019] [Indexed: 02/06/2023]
Abstract
Rare diseases are very difficult to study mechanistically and to develop therapies for because of the scarcity of patients. Here, the rare neuro-metabolic disorder Rett syndrome (RTT) is discussed as a prototype for precision medicine, demonstrating how mouse models have led to an understanding of the development of symptoms. RTT is caused by mutations in the X-linked gene methyl-CpG-binding protein 2 (MECP2). Mecp2-mutant mice are being used in preclinical studies that target the MECP2 gene directly, or its downstream pathways. Importantly, this work may improve the health of RTT patients. Clinical presentation may vary widely among individuals based on their mutation, but also because of the degree of X chromosome inactivation and the presence of modifier genes. Because it is a complex disorder involving many organ systems, it is likely that recovery of RTT patients will involve a combination of treatments. Precision medicine is warranted to provide the best efficacy to individually treat RTT patients.
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Leubitz A, Frydman-Marom A, Sharpe N, van Duzer J, Campbell KCM, Vanhoutte F. Safety, Tolerability, and Pharmacokinetics of Single Ascending Doses of ELX-02, a Potential Treatment for Genetic Disorders Caused by Nonsense Mutations, in Healthy Volunteers. Clin Pharmacol Drug Dev 2019; 8:984-994. [PMID: 30650260 DOI: 10.1002/cpdd.647] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 12/03/2018] [Indexed: 12/13/2022]
Abstract
ELX-02 is an investigational synthetic eukaryotic ribosome-selective glycoside optimized as a translational read-through molecule that induces read through of nonsense mutations, resulting in normally localized full-length functional proteins. ELX-02 is being developed as a therapy for genetic diseases caused by nonsense mutations. Two phase 1a, randomized, double-blind placebo-controlled, single-ascending-dose studies were conducted in healthy human subjects to evaluate the safety and pharmacokinetics of ELX-02. Single subcutaneously injected doses of ELX-02 between 0.3 mg/kg and 7.5 mg/kg showed an acceptable safety profile without severe or serious drug-related adverse events, including a lack of renal and ototoxicity events. Injection of ELX-02 resulted in a rapid time to peak concentration and elimination phase, with complete elimination from the vascular compartment within 10 hours. ELX-02 area under the concentration-time curve to infinity showed dose-exposure linearity (24-fold increase for a 25-fold dose increase), and the maximum concentration showed dose proportionality (17-fold increase for a 25-fold increase). The mean apparent volume of distribution was dose dependent, suggesting an increased distribution and tissue uptake of ELX-02 at higher doses. The primary route of excretion was in the urine, with the majority of the compound excreted unchanged. These results support the evaluation of the safety, pharmacokinetics, and efficacy of repeat dosing in future studies.
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Abstract
Cystic kidneys are common causes of end-stage renal disease, both in children and in adults. Autosomal dominant polycystic kidney disease (ADPKD) and autosomal recessive polycystic kidney disease (ARPKD) are cilia-related disorders and the two main forms of monogenic cystic kidney diseases. ADPKD is a common disease that mostly presents in adults, whereas ARPKD is a rarer and often more severe form of polycystic kidney disease (PKD) that usually presents perinatally or in early childhood. Cell biological and clinical research approaches have expanded our knowledge of the pathogenesis of ADPKD and ARPKD and revealed some mechanistic overlap between them. A reduced 'dosage' of PKD proteins is thought to disturb cell homeostasis and converging signalling pathways, such as Ca2+, cAMP, mechanistic target of rapamycin, WNT, vascular endothelial growth factor and Hippo signalling, and could explain the more severe clinical course in some patients with PKD. Genetic diagnosis might benefit families and improve the clinical management of patients, which might be enhanced even further with emerging therapeutic options. However, many important questions about the pathogenesis of PKD remain. In this Primer, we provide an overview of the current knowledge of PKD and its treatment.
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Affiliation(s)
- Carsten Bergmann
- Department of Medicine, University Hospital Freiburg, Freiburg, Germany.
| | - Lisa M. Guay-Woodford
- Center for Translational Science, Children’s National Health System, Washington, DC, USA
| | - Peter C. Harris
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
| | - Shigeo Horie
- Department of Urology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Dorien J. M. Peters
- Department of Human Genetics, Leiden University Medical Center, Leiden, Netherlands
| | - Vicente E. Torres
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
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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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Ferrarese M, Testa MF, Balestra D, Bernardi F, Pinotti M, Branchini A. Secretion of wild-type factor IX upon readthrough over F9 pre-peptide nonsense mutations causing hemophilia B. Hum Mutat 2018; 39:702-708. [PMID: 29388273 DOI: 10.1002/humu.23404] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 01/16/2018] [Accepted: 01/19/2018] [Indexed: 12/30/2022]
Abstract
Pre-peptide regions of secreted proteins display wide sequence variability, even among highly homologous proteins such as coagulation factors, and are intracellularly removed, thus potentially favoring secretion of wild-type proteins upon suppression of nonsense mutations (translational readthrough). As models we selected F9 nonsense mutations with readthrough-favorable features affecting the pre-peptide and pro-peptide regions of coagulation factor IX (FIX), which cause hemophilia B (HB). Only the p.Gly21Ter (c.61G > T) in the variable pre-peptide hydrophobic core significantly responded (secretion, 4.1 ± 0.5% of wild-type; coagulant activity, 4.0 ± 0.3%) to the readthrough-inducer geneticin. Strikingly, for the p.Gly21Ter mutation, the resulting specific coagulant activity (0.96 ± 0.11) was compatible with normal function, thus suggesting secretion of FIX with wild-type features upon readthrough and removal of pre-peptide. Expression of the predicted readthrough-deriving missense variants (Gly21Trp/Cys/Arg) revealed a preserved specific activity (ranging from 0.84 to 0.98), thus supporting our observation. Conversely, rescue of the p.Cys28Ter (c.84T > A) and p.Lys45Ter (c.133A > T) was prevented by constraints of adjacent cleavage sites, a finding consistent with the association of most missense mutations affecting these regions with severe or moderate HB. Overall, our data indicate that suppression of nonsense mutations in the pre-peptide core preserves mature protein features, thus making this class of mutations preferred candidates for therapeutic readthrough.
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Affiliation(s)
- Mattia Ferrarese
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Maria Francesca Testa
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Dario Balestra
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Francesco Bernardi
- 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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Huang L, Low A, Damle SS, Keenan MM, Kuntz S, Murray SF, Monia BP, Guo S. Antisense suppression of the nonsense mediated decay factor Upf3b as a potential treatment for diseases caused by nonsense mutations. Genome Biol 2018; 19:4. [PMID: 29334995 PMCID: PMC5769327 DOI: 10.1186/s13059-017-1386-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 12/29/2017] [Indexed: 01/08/2023] Open
Abstract
Background About 11% of all human genetic diseases are caused by nonsense mutations that generate premature translation termination codons (PTCs) in messenger RNAs (mRNA). PTCs not only lead to the production of truncated proteins, but also often result in decreased mRNA abundance due to nonsense-mediated mRNA decay (NMD). Although pharmacological inhibition of NMD could be an attractive therapeutic approach for the treatment of diseases caused by nonsense mutations, NMD also regulates the expression of 10–20% of the normal transcriptome. Results Here, we investigate whether NMD can be inhibited to stabilize mutant mRNAs, which may subsequently produce functional proteins, without having a major impact on the normal transcriptome. We develop antisense oligonucleotides (ASOs) to systematically deplete each component in the NMD pathway. We find that ASO-mediated depletion of each NMD factor elicits different magnitudes of NMD inhibition in vitro and are differentially tolerated in normal mice. Among all of the NMD factors, Upf3b depletion is well tolerated, consistent with previous reports that UPF3B is not essential for development and regulates only a subset of the endogenous NMD substrates. While minimally impacting the normal transcriptome, Upf3b-ASO treatment significantly stabilizes the PTC-containing dystrophin mRNA in mdx mice and coagulation factor IX mRNA in a hemophilia mouse model. Furthermore, when combined with reagents promoting translational read-through, Upf3b-ASO treatment leads to the production of functional factor IX protein in hemophilia mice. Conclusions These data demonstrate that ASO-mediated reduction of the NMD factor Upf3b could be an effective and safe approach for the treatment of diseases caused by nonsense mutations. Electronic supplementary material The online version of this article (doi:10.1186/s13059-017-1386-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lulu Huang
- Ionis Pharmaceuticals, Inc., Carlsbad, California, USA
| | - Audrey Low
- Ionis Pharmaceuticals, Inc., Carlsbad, California, USA
| | - Sagar S Damle
- Ionis Pharmaceuticals, Inc., Carlsbad, California, USA
| | | | - Steven Kuntz
- Ionis Pharmaceuticals, Inc., Carlsbad, California, USA
| | | | - Brett P Monia
- Ionis Pharmaceuticals, Inc., Carlsbad, California, USA
| | - Shuling Guo
- Ionis Pharmaceuticals, Inc., Carlsbad, California, USA.
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Thompson JA, De Roach JN, McLaren TL, Lamey TM. A Mini-Review: Leber Congenital Amaurosis: Identification of Disease-Causing Variants and Personalised Therapies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1074:265-271. [DOI: 10.1007/978-3-319-75402-4_32] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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67
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Banning A, Schiff M, Tikkanen R. Amlexanox provides a potential therapy for nonsense mutations in the lysosomal storage disorder Aspartylglucosaminuria. Biochim Biophys Acta Mol Basis Dis 2017; 1864:668-675. [PMID: 29247835 DOI: 10.1016/j.bbadis.2017.12.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 11/17/2017] [Accepted: 12/11/2017] [Indexed: 10/18/2022]
Abstract
Aspartylglucosaminuria (AGU) is a lysosomal storage disorder caused by mutations in the gene for aspartylglucosaminidase (AGA). This enzyme participates in glycoprotein degradation in lysosomes. AGU results in progressive mental retardation, and no curative therapy is currently available. We have here characterized the consequences of AGA gene mutations in a compound heterozygous patient who exhibits a missense mutation producing a Ser72Pro substitution in one allele, and a nonsense mutation Trp168X in the other. Ser72 is not a catalytic residue, but is required for the stabilization of the active site conformation. Thus, Ser72Pro exchange impairs the autocatalytic activation of the AGA precursor, and results in a considerable reduction of the enzyme activity and in altered AGA precursor processing. Betaine, which can partially rescue the AGA activity in AGU patients carrying certain missense mutations, turned out to be ineffective in the case of Ser72Pro substitution. The Trp168X nonsense allele results in complete lack of AGA polypeptide due to nonsense-mediated decay (NMD) of the mRNA. Amlexanox, which inhibits NMD and causes a translational read-through, facilitated the synthesis of a full-length, functional AGA protein from the nonsense allele. This could be demonstrated as presence of the AGA polypeptide and increased enzyme activity upon Amlexanox treatment. Furthermore, in the Ser72Pro/Trp168X expressing cells, Amlexanox induced a synergistic increase in AGA activity and polypeptide processing due to enhanced processing of the Ser72Pro polypeptide. Our data show for the first time that Amlexanox might provide a valid therapy for AGU.
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Affiliation(s)
- Antje Banning
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany
| | - Manuel Schiff
- AP-HP, Robert Debré Hospital, Reference Center for Inherited Metabolic Diseases, University Paris Diderot-Sorbonne Paris Cité, PROTECT, INSERM U1141, Paris, France
| | - Ritva Tikkanen
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany.
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68
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Thompson JA, De Roach JN, McLaren TL, Montgomery HE, Hoffmann LH, Campbell IR, Chen FK, Mackey DA, Lamey TM. The genetic profile of Leber congenital amaurosis in an Australian cohort. Mol Genet Genomic Med 2017; 5:652-667. [PMID: 29178642 PMCID: PMC5702575 DOI: 10.1002/mgg3.321] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 06/27/2017] [Accepted: 06/29/2017] [Indexed: 12/21/2022] Open
Abstract
Background Leber congenital amaurosis (LCA) is a severe visual impairment responsible for infantile blindness, representing ~5% of all inherited retinal dystrophies. LCA encompasses a group of heterogeneous disorders, with 24 genes currently implicated in pathogenesis. Such clinical and genetic heterogeneity poses great challenges for treatment, with personalized therapies anticipated to be the best treatment candidates. Unraveling the individual genetic etiology of disease is a prerequisite for personalized therapies, and could identify potential treatment candidates, inform patient management, and discriminate syndromic forms of disease. Methods We have genetically analyzed 45 affected and 82 unaffected individuals from 34 unrelated LCA pedigrees using predominantly next‐generation sequencing and Array CGH technology. Results We present the molecular findings for an Australian LCA cohort, sourced from the Australian Inherited Retinal Disease Registry & DNA Bank. CEP290 and GUCY2D mutations, each represent 19% of unrelated LCA cases, followed by NMNAT1 (12%). Genetic subtypes were consistent with other reports, and were resolved in 90% of this cohort. Conclusion The high resolution rate achieved, equivalent to recent findings using whole exome/genome sequencing, reflects the progression from hypothesis (LCA Panel) to non‐hypothesis (RD Panel) testing and, coupled with Array CGH analysis, is a highly effective first‐tier test for LCA.
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Affiliation(s)
- Jennifer A Thompson
- Australian Inherited Retinal Disease Registry and DNA Bank, Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
| | - John N De Roach
- Australian Inherited Retinal Disease Registry and DNA Bank, Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia.,Centre for Ophthalmology and Visual Science, The University of Western Australia, Crawley, Western Australia, Australia
| | - Terri L McLaren
- Australian Inherited Retinal Disease Registry and DNA Bank, Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
| | - Hannah E Montgomery
- Australian Inherited Retinal Disease Registry and DNA Bank, Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
| | - Ling H Hoffmann
- Australian Inherited Retinal Disease Registry and DNA Bank, Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
| | - Isabella R Campbell
- Australian Inherited Retinal Disease Registry and DNA Bank, Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
| | - Fred K Chen
- Australian Inherited Retinal Disease Registry and DNA Bank, Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia.,Centre for Ophthalmology and Visual Science, The University of Western Australia, Crawley, Western Australia, Australia.,Lions Eye Institute, Nedlands, Western Australia, Australia.,Department of Ophthalmology, Royal Perth Hospital, Perth, Western Australia, Australia
| | - David A Mackey
- Australian Inherited Retinal Disease Registry and DNA Bank, Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia.,Centre for Ophthalmology and Visual Science, The University of Western Australia, Crawley, Western Australia, Australia.,Lions Eye Institute, Nedlands, Western Australia, Australia
| | - Tina M Lamey
- Australian Inherited Retinal Disease Registry and DNA Bank, Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia.,Centre for Ophthalmology and Visual Science, The University of Western Australia, Crawley, Western Australia, Australia
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Neuhaus C, Eisenberger T, Decker C, Nagl S, Blank C, Pfister M, Kennerknecht I, Müller-Hofstede C, Charbel Issa P, Heller R, Beck B, Rüther K, Mitter D, Rohrschneider K, Steinhauer U, Korbmacher HM, Huhle D, Elsayed SM, Taha HM, Baig SM, Stöhr H, Preising M, Markus S, Moeller F, Lorenz B, Nagel-Wolfrum K, Khan AO, Bolz HJ. Next-generation sequencing reveals the mutational landscape of clinically diagnosed Usher syndrome: copy number variations, phenocopies, a predominant target for translational read-through, and PEX26 mutated in Heimler syndrome. Mol Genet Genomic Med 2017; 5:531-552. [PMID: 28944237 PMCID: PMC5606877 DOI: 10.1002/mgg3.312] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 06/06/2017] [Accepted: 06/09/2017] [Indexed: 12/23/2022] Open
Abstract
Background Combined retinal degeneration and sensorineural hearing impairment is mostly due to autosomal recessive Usher syndrome (USH1: congenital deafness, early retinitis pigmentosa (RP); USH2: progressive hearing impairment, RP). Methods Sanger sequencing and NGS of 112 genes (Usher syndrome, nonsyndromic deafness, overlapping conditions), MLPA, and array‐CGH were conducted in 138 patients clinically diagnosed with Usher syndrome. Results A molecular diagnosis was achieved in 97% of both USH1 and USH2 patients, with biallelic mutations in 97% (USH1) and 90% (USH2), respectively. Quantitative readout reliably detected CNVs (confirmed by MLPA or array‐CGH), qualifying targeted NGS as one tool for detecting point mutations and CNVs. CNVs accounted for 10% of identified USH2A alleles, often in trans to seemingly monoallelic point mutations. We demonstrate PTC124‐induced read‐through of the common p.Trp3955* nonsense mutation (13% of detected USH2A alleles), a potential therapy target. Usher gene mutations were found in most patients with atypical Usher syndrome, but the diagnosis was adjusted in case of double homozygosity for mutations in OTOA and NR2E3, genes implicated in isolated deafness and RP. Two patients with additional enamel dysplasia had biallelic PEX26 mutations, for the first time linking this gene to Heimler syndrome. Conclusion Targeted NGS not restricted to Usher genes proved beneficial in uncovering conditions mimicking Usher syndrome.
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Affiliation(s)
| | | | | | - Sandra Nagl
- Bioscientia Center for Human GeneticsIngelheimGermany
| | | | - Markus Pfister
- HNO-Praxis SarnenSarnenSwitzerland.,Molecular Genetics, THRCDepartment of OtolaryngologyUniversity of TübingenTübingenGermany
| | - Ingo Kennerknecht
- Institute of Human GeneticsWestfälische Wilhelms-UniversitätMünsterGermany
| | | | - Peter Charbel Issa
- Department of OphthalmologyUniversity of BonnBonnGermany.,Center for Rare Diseases Bonn (ZSEB)University of BonnBonnGermany.,Oxford Eye HospitalUniversity of OxfordOxfordUK
| | - Raoul Heller
- Institute of Human GeneticsUniversity Hospital of CologneCologneGermany
| | - Bodo Beck
- Institute of Human GeneticsUniversity Hospital of CologneCologneGermany
| | | | - Diana Mitter
- Institute of Human GeneticsUniversity of Leipzig Hospitals and ClinicsLeipzigGermany
| | | | | | - Heike M Korbmacher
- Department of OrthodonticsGiessen and Marburg University Hospital, Marburg CampusMarburgGermany
| | | | - Solaf M Elsayed
- Medical Genetics CenterCairoEgypt.,Children's HospitalAin Shams UniversityCairoEgypt
| | | | - Shahid M Baig
- Human Molecular Genetics LaboratoryHealth Biotechnology DivisionNational Institute for Biotechnology and Genetic Engineering (NIBGE)FaisalabadPakistan
| | - Heidi Stöhr
- Department of Human GeneticsUniversity Medical Center RegensburgRegensburgGermany
| | - Markus Preising
- Department of OphthalmologyJustus-Liebig-University GiessenGiessenGermany
| | | | - Fabian Moeller
- Department of Cell and Matrix BiologyInstitute of Zoology, Johannes GutenbergUniversity of MainzMainzGermany
| | - Birgit Lorenz
- Department of OphthalmologyJustus-Liebig-University GiessenGiessenGermany
| | - Kerstin Nagel-Wolfrum
- Department of Cell and Matrix BiologyInstitute of Zoology, Johannes GutenbergUniversity of MainzMainzGermany
| | - Arif O Khan
- Division of Pediatric OphthalmologyKing Khaled Eye Specialist HospitalRiyadhSaudi Arabia.,Eye InstituteCleveland ClinicAbu DhabiUAE
| | - Hanno J Bolz
- Bioscientia Center for Human GeneticsIngelheimGermany.,Institute of Human GeneticsUniversity Hospital of CologneCologneGermany
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Wiechers L, Samanta A, Nagel-Wolfrum K. Das Überlesen von Nonsense-Mutationen. MED GENET-BERLIN 2017. [DOI: 10.1007/s11825-017-0136-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Zusammenfassung
Nonsense-Mutationen weisen eine Inzidenz von etwa 12 % bezogen auf alle krankheitsverursachenden Mutationen auf. Eine ähnliche Rate gilt für Netzhauterkrankungen. Ein speziell auf diesen Mutationstyp ausgerichteter Therapieansatz könnte somit praktikabel und ökonomisch im Sinne einer Therapie „eine für viele“ sein. Nonsense-Mutationen führen zu vorzeitigen Terminationscodons (PTCs), wodurch die Degradation der mRNA über den „nonsense-mediated decay“ (NMD) induziert werden kann oder die Translation am PTC endet und ein verkürztes, zumeist nicht mehr funktionelles Protein synthetisiert wird. Ein pharmakogenetischer Ansatz induziert das Überlesen („read-through“) von PTCs und erlaubt somit die Synthese von vollständigen Proteinen. Die hierbei eingesetzten Wirkstoffe werden als TRIDs („translational read-through inducing drugs“) bezeichnet. Die ersten identifizierten TRIDs gehören zur Klasse der Aminoglykosidantibiotika. Modernere TRIDs sind Amlexanox, Ataluren und Derivate von Aminoglykosidantibiotika. Während Aminoglykoside eine hohe Oto‑, Nephro- und Retinotoxizität aufweisen, zeichnen sich die modernen TRIDs durch eine verbesserte Verträglichkeit aus. Eine Vielzahl von präklinischen Studien belegt die Überlese-Effizienz von TRIDs bei Nonsense-Mutationen und zeigt die Funktionalität der wiederhergestellten Proteine in Zellkultur, Tiermodellen und patientenspezifischen Zellen. Für die Therapie von Netzhauterkrankungen werden systemische und lokale Applikationen evaluiert. Patientenspezifische Zellen stellen ein personalisiertes Screeningmodell für die Identifizierung eines wirksamen TRID dar. Der pharmakogenetische Überlese-Ansatz könnte in Zukunft für jeden Patienten, dessen Netzhauterkrankung durch eine Nonsense-Mutation verursacht wird, eine personalisierte Therapie erlauben.
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Affiliation(s)
- Lisa Wiechers
- Aff1 0000 0001 1941 7111 grid.5802.f Molekulare Zellbiologie (Therapie-Team), Institut für Molekulare Physiologie Johannes Gutenberg-Universität Mainz J.-J.-Becher-Weg 7 55099 Mainz Deutschland
| | - Ananya Samanta
- Aff1 0000 0001 1941 7111 grid.5802.f Molekulare Zellbiologie (Therapie-Team), Institut für Molekulare Physiologie Johannes Gutenberg-Universität Mainz J.-J.-Becher-Weg 7 55099 Mainz Deutschland
| | - Kerstin Nagel-Wolfrum
- Aff1 0000 0001 1941 7111 grid.5802.f Molekulare Zellbiologie (Therapie-Team), Institut für Molekulare Physiologie Johannes Gutenberg-Universität Mainz J.-J.-Becher-Weg 7 55099 Mainz Deutschland
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Aminoglycoside-driven biosynthesis of selenium-deficient Selenoprotein P. Sci Rep 2017; 7:4391. [PMID: 28663583 PMCID: PMC5491492 DOI: 10.1038/s41598-017-04586-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 05/17/2017] [Indexed: 12/17/2022] Open
Abstract
Selenoprotein biosynthesis relies on the co-translational insertion of selenocysteine in response to UGA codons. Aminoglycoside antibiotics interfere with ribosomal function and may cause codon misreading. We hypothesized that biosynthesis of the selenium (Se) transporter selenoprotein P (SELENOP) is particularly sensitive to antibiotics due to its ten in frame UGA codons. As liver regulates Se metabolism, we tested the aminoglycosides G418 and gentamicin in hepatoma cell lines (HepG2, Hep3B and Hepa1-6) and in experimental mice. In vitro, SELENOP levels increased strongly in response to G418, whereas expression of the glutathione peroxidases GPX1 and GPX2 was marginally affected. Se content of G418-induced SELENOP was dependent on Se availability, and was completely suppressed by G418 under Se-poor conditions. Selenocysteine residues were replaced mainly by cysteine, tryptophan and arginine in a codon-specific manner. Interestingly, in young healthy mice, antibiotic treatment failed to affect Selenop biosynthesis to a detectable degree. These findings suggest that the interfering activity of aminoglycosides on selenoprotein biosynthesis can be severe, but depend on the Se status, and other parameters likely including age and general health. Focused analyses with aminoglycoside-treated patients are needed next to evaluate a possible interference of selenoprotein biosynthesis by the antibiotics and elucidate potential side effects.
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May-Simera H, Nagel-Wolfrum K, Wolfrum U. Cilia - The sensory antennae in the eye. Prog Retin Eye Res 2017; 60:144-180. [PMID: 28504201 DOI: 10.1016/j.preteyeres.2017.05.001] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 05/04/2017] [Accepted: 05/08/2017] [Indexed: 12/21/2022]
Abstract
Cilia are hair-like projections found on almost all cells in the human body. Originally believed to function merely in motility, the function of solitary non-motile (primary) cilia was long overlooked. Recent research has demonstrated that primary cilia function as signalling hubs that sense environmental cues and are pivotal for organ development and function, tissue hoemoestasis, and maintenance of human health. Cilia share a common anatomy and their diverse functional features are achieved by evolutionarily conserved functional modules, organized into sub-compartments. Defects in these functional modules are responsible for a rapidly growing list of human diseases collectively termed ciliopathies. Ocular pathogenesis is common in virtually all classes of syndromic ciliopathies, and disruptions in cilia genes have been found to be causative in a growing number of non-syndromic retinal dystrophies. This review will address what is currently known about cilia contribution to visual function. We will focus on the molecular and cellular functions of ciliary proteins and their role in the photoreceptor sensory cilia and their visual phenotypes. We also highlight other ciliated cell types in tissues of the eye (e.g. lens, RPE and Müller glia cells) discussing their possible contribution to disease progression. Progress in basic research on the cilia function in the eye is paving the way for therapeutic options for retinal ciliopathies. In the final section we describe the latest advancements in gene therapy, read-through of non-sense mutations and stem cell therapy, all being adopted to treat cilia dysfunction in the retina.
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Affiliation(s)
- Helen May-Simera
- Institute of Molecular Physiology, Cilia Biology, Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany
| | - Kerstin Nagel-Wolfrum
- Institute of Molecular Physiology, Molecular Cell Biology, Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany
| | - Uwe Wolfrum
- Institute of Molecular Physiology, Molecular Cell Biology, Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany.
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Geraets RD, Langin LM, Cain JT, Parker CM, Beraldi R, Kovacs AD, Weimer JM, Pearce DA. A tailored mouse model of CLN2 disease: A nonsense mutant for testing personalized therapies. PLoS One 2017; 12:e0176526. [PMID: 28464005 PMCID: PMC5413059 DOI: 10.1371/journal.pone.0176526] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 03/27/2017] [Indexed: 12/22/2022] Open
Abstract
The Neuronal Ceroid Lipofuscinoses (NCLs), also known as Batten disease, result from mutations in over a dozen genes. Although, adults are susceptible, the NCLs are frequently classified as pediatric neurodegenerative diseases due to their greater pediatric prevalence. Initial clinical presentation usually consists of either seizures or retinopathy but develops to encompass both in conjunction with declining motor and cognitive function. The NCLs result in premature death due to the absence of curative therapies. Nevertheless, preclinical and clinical trials exist for various therapies. However, the genotypes of NCL animal models determine which therapeutic approaches can be assessed. Mutations of the CLN2 gene encoding a soluble lysosomal enzyme, tripeptidyl peptidase 1 (TPP1), cause late infantile NCL/CLN2 disease. The genotype of the original mouse model of CLN2 disease, Cln2-/-, excludes mutation guided therapies like antisense oligonucleotides and nonsense suppression. Therefore, the purpose of this study was to develop a model of CLN2 disease that allows for the assessment of all therapeutic approaches. Nonsense mutations in CLN2 disease are frequent, the most common being CLN2R208X. Thus, we created a mouse model that carries a mutation equivalent to the human p.R208X mutation. Molecular assessment of Cln2R207X/R207X tissues determined significant reduction in Cln2 transcript abundance and TPP1 enzyme activity. This reduction leads to the development of neurological impairment (e.g. tremors) and neuropathology (e.g. astrocytosis). Collectively, these assessments indicate that the Cln2R207X/R207X mouse is a valid CLN2 disease model which can be used for the preclinical evaluation of all therapeutic approaches including mutation guided therapies.
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Affiliation(s)
- Ryan D. Geraets
- Children’s Health Research Center, Sanford Research, Sioux Falls, South Dakota, United States of America
- Sanford School of Medicine at the University of South Dakota, Sioux Falls, South Dakota, United States of America
| | - Logan M. Langin
- Children’s Health Research Center, Sanford Research, Sioux Falls, South Dakota, United States of America
| | - Jacob T. Cain
- Children’s Health Research Center, Sanford Research, Sioux Falls, South Dakota, United States of America
| | - Camille M. Parker
- Children’s Health Research Center, Sanford Research, Sioux Falls, South Dakota, United States of America
| | - Rosanna Beraldi
- Children’s Health Research Center, Sanford Research, Sioux Falls, South Dakota, United States of America
| | - Attila D. Kovacs
- Children’s Health Research Center, Sanford Research, Sioux Falls, South Dakota, United States of America
- Sanford School of Medicine at the University of South Dakota, Sioux Falls, South Dakota, United States of America
| | - Jill M. Weimer
- Children’s Health Research Center, Sanford Research, Sioux Falls, South Dakota, United States of America
- Sanford School of Medicine at the University of South Dakota, Sioux Falls, South Dakota, United States of America
| | - David A. Pearce
- Children’s Health Research Center, Sanford Research, Sioux Falls, South Dakota, United States of America
- Sanford School of Medicine at the University of South Dakota, Sioux Falls, South Dakota, United States of America
- * E-mail:
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Richardson R, Smart M, Tracey-White D, Webster AR, Moosajee M. Mechanism and evidence of nonsense suppression therapy for genetic eye disorders. Exp Eye Res 2017; 155:24-37. [PMID: 28065590 DOI: 10.1016/j.exer.2017.01.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 11/24/2016] [Accepted: 01/04/2017] [Indexed: 01/09/2023]
Abstract
Between 5 and 70% of genetic disease is caused by in-frame nonsense mutations, which introduce a premature termination codon (PTC) within the disease-causing gene. Consequently, during translation, non-functional or gain-of-function truncated proteins of pathological significance, are formed. Approximately 50% of all inherited retinal disorders have been associated with PTCs, highlighting the importance of novel pharmacological or gene correction therapies in ocular disease. Pharmacological nonsense suppression of PTCs could delineate a therapeutic strategy that treats the mutation in a gene- and disease-independent manner. This approach aims to suppress the fidelity of the ribosome during protein synthesis so that a near-cognate aminoacyl-tRNA, which shares two of the three nucleotides of the PTC, can be inserted into the peptide chain, allowing translation to continue, and a full-length functional protein to be produced. Here we discuss the mechanisms and evidence of nonsense suppression agents, including the small molecule drug ataluren (or PTC124) and next generation 'designer' aminoglycosides, for the treatment of genetic eye disease.
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Affiliation(s)
- Rose Richardson
- Department of Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, UK
| | - Matthew Smart
- Department of Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, UK
| | - Dhani Tracey-White
- Department of Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, UK
| | - Andrew R Webster
- Department of Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Mariya Moosajee
- Department of Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK.
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Keeling KM. Nonsense Suppression as an Approach to Treat Lysosomal Storage Diseases. Diseases 2016; 4:32. [PMID: 28367323 PMCID: PMC5370586 DOI: 10.3390/diseases4040032] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 10/14/2016] [Indexed: 02/08/2023] Open
Abstract
In-frame premature termination codons (PTCs) (also referred to as nonsense mutations) comprise ~10% of all disease-associated gene lesions. PTCs reduce gene expression in two ways. First, PTCs prematurely terminate translation of an mRNA, leading to the production of a truncated polypeptide that often lacks normal function and/or is unstable. Second, PTCs trigger degradation of an mRNA by activating nonsense-mediated mRNA decay (NMD), a cellular pathway that recognizes and degrades mRNAs containing a PTC. Thus, translation termination and NMD are putative therapeutic targets for the development of treatments for genetic diseases caused by PTCs. Over the past decade, significant progress has been made in the identification of compounds with the ability to suppress translation termination of PTCs (also referred to as readthrough). More recently, NMD inhibitors have also been explored as a way to enhance the efficiency of PTC suppression. Due to their relatively low threshold for correction, lysosomal storage diseases are a particularly relevant group of diseases to investigate the feasibility of nonsense suppression as a therapeutic approach. In this review, the current status of PTC suppression and NMD inhibition as potential treatments for lysosomal storage diseases will be discussed.
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Affiliation(s)
- Kim M Keeling
- Department of Biochemistry and Molecular Genetics, Gregory Fleming Cystic Fibrosis Research Center, Comprehensive Arthritis, Musculoskeletal, Bone, and Autoimmunity Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA; ; Tel.: +1-205-975-6585
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Barbon E, Ferrarese M, van Wittenberghe L, Sanatine P, Ronzitti G, Collaud F, Colella P, Pinotti M, Mingozzi F. Transposon-mediated Generation of Cellular and Mouse Models of Splicing Mutations to Assess the Efficacy of snRNA-based Therapeutics. MOLECULAR THERAPY. NUCLEIC ACIDS 2016; 5:e392. [PMID: 27898092 PMCID: PMC5155329 DOI: 10.1038/mtna.2016.97] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 09/06/2016] [Indexed: 12/21/2022]
Abstract
Disease-causing splicing mutations can be rescued by variants of the U1 small nuclear RNA (U1snRNAs). However, the evaluation of the efficacy and safety of modified U1snRNAs as therapeutic tools is limited by the availability of cellular and animal models specific for a given mutation. Hence, we exploited the hyperactive Sleeping Beauty transposon system (SB100X) to integrate human factor IX (hFIX) minigenes into genomic DNA in vitro and in vivo. We generated stable HEK293 cell lines and C57BL/6 mice harboring splicing-competent hFIX minigenes either wild type (SChFIX-wt) or mutated (SChFIXex5-2C). In both models the SChFIXex5-2C variant, found in patients affected by Hemophilia B, displayed an aberrant splicing pattern characterized by exon 5 skipping. This allowed us to test, for the first time in a genomic DNA context, the efficacy of the snRNA U1-fix9, delivered with an adeno-associated virus (AAV) vector. With this approach, we showed rescue of the correct splicing pattern of hFIX mRNA, leading to hFIX protein expression. These data validate the SB100X as a versatile tool to quickly generate models of human genetic mutations, to study their effect in a stable DNA context and to assess mutation-targeted therapeutic strategies.
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Affiliation(s)
| | - Mattia Ferrarese
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | | | | | | | | | | | - Mirko Pinotti
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Federico Mingozzi
- Genethon, Evry, France
- INSERM U951, Evry, France
- Institute of Myology, University Pierre and Marie Curie – Paris 6, Paris, France
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Bukowy-Bieryllo Z, Dabrowski M, Witt M, Zietkiewicz E. Aminoglycoside-stimulated readthrough of premature termination codons in selected genes involved in primary ciliary dyskinesia. RNA Biol 2016; 13:1041-1050. [PMID: 27618201 PMCID: PMC5056772 DOI: 10.1080/15476286.2016.1219832] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Translational readthrough of premature termination codons (PTCs) induced by pharmacological compounds has proven to be an effective way of restoring functional protein expression and reducing symptoms in several genetic disorders. We tested the potential of different concentrations of several aminoglycosides (AAGs) for promoting PTC-readthrough in 5 genes involved in the pathogenesis of primary ciliary dyskinesia, an inherited disorder caused by the dysfunction of motile cilia and flagella. The efficiency of readthrough stimulation of PTCs cloned in dual reporter vectors was examined in 2 experimental settings: in vitro (transcription/translation system) and ex vivo (transiently transfected epithelial cell line). PTC-readthrough was observed in 5 of the 16 mutations analyzed. UGA codons were more susceptible to AAG-stimulated readthrough than UAG; no suppression of UAA was observed. The efficiency of PTC-readthrough in vitro (from less than 1% to ∼28% of the translation from the corresponding wild-type constructs) differed with the AAG type and concentration, and depended on the combination of AAG and PTC, indicating that each PTC has to be individually tested with a range of stimulating compounds. The maximal values of PTC suppression observed in the ex vivo experiments were, depending on AAG used, 3–5 times lower than the corresponding values in vitro, despite using AAG concentrations that were 2 orders of magnitude higher. This indicates that, while the in vitro system is sufficient to examine the readthrough-susceptibility of PTCs, it is not sufficient to test the compounds potential to stimulate PTC-readthrough in the living cells. Most of the tested compounds (except for G418) at their highest concentrations did not disturb ciliogenesis in the cultures of primary respiratory epithelial cells from healthy donors.
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Affiliation(s)
| | - Maciej Dabrowski
- a Institute of Human Genetics, Polish Academy of Sciences , Poznan , Poland
| | - Michał Witt
- a Institute of Human Genetics, Polish Academy of Sciences , Poznan , Poland
| | - Ewa Zietkiewicz
- a Institute of Human Genetics, Polish Academy of Sciences , Poznan , Poland
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