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Premchandar A, Ming R, Baiad A, Da Fonte DF, Xu H, Faubert D, Veit G, Lukacs GL. Readthrough-induced misincorporated amino acid ratios guide mutant-specific therapeutic approaches for two CFTR nonsense mutations. Front Pharmacol 2024; 15:1389586. [PMID: 38725656 PMCID: PMC11079177 DOI: 10.3389/fphar.2024.1389586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Accepted: 03/28/2024] [Indexed: 05/12/2024] Open
Abstract
Cystic fibrosis (CF) is a monogenic disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. Premature termination codons (PTCs) represent ∼9% of CF mutations that typically cause severe expression defects of the CFTR anion channel. Despite the prevalence of PTCs as the underlying cause of genetic diseases, understanding the therapeutic susceptibilities of their molecular defects, both at the transcript and protein levels remains partially elucidated. Given that the molecular pathologies depend on the PTC positions in CF, multiple pharmacological interventions are required to suppress the accelerated nonsense-mediated mRNA decay (NMD), to correct the CFTR conformational defect caused by misincorporated amino acids, and to enhance the inefficient stop codon readthrough. The G418-induced readthrough outcome was previously investigated only in reporter models that mimic the impact of the local sequence context on PTC mutations in CFTR. To identify the misincorporated amino acids and their ratios for PTCs in the context of full-length CFTR readthrough, we developed an affinity purification (AP)-tandem mass spectrometry (AP-MS/MS) pipeline. We confirmed the incorporation of Cys, Arg, and Trp residues at the UGA stop codons of G542X, R1162X, and S1196X in CFTR. Notably, we observed that the Cys and Arg incorporation was favored over that of Trp into these CFTR PTCs, suggesting that the transcript sequence beyond the proximity of PTCs and/or other factors can impact the amino acid incorporation and full-length CFTR functional expression. Additionally, establishing the misincorporated amino acid ratios in the readthrough CFTR PTCs aided in maximizing the functional rescue efficiency of PTCs by optimizing CFTR modulator combinations. Collectively, our findings contribute to the understanding of molecular defects underlying various CFTR nonsense mutations and provide a foundation to refine mutation-dependent therapeutic strategies for various CF-causing nonsense mutations.
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Affiliation(s)
| | - Ruiji Ming
- Department of Physiology, McGill University, Montréal, QC, Canada
| | - Abed Baiad
- Department of Physiology, McGill University, Montréal, QC, Canada
| | | | - Haijin Xu
- Department of Physiology, McGill University, Montréal, QC, Canada
| | - Denis Faubert
- IRCM Mass Spectrometry and Proteomics Platform, Institut de Recherches Cliniques de Montréal, Montréal, QC, Canada
| | - Guido Veit
- Department of Physiology, McGill University, Montréal, QC, Canada
| | - Gergely L. Lukacs
- Department of Physiology, McGill University, Montréal, QC, Canada
- Department of Biochemistry, McGill University, Montréal, QC, Canada
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Allan KM, Astore MA, Kardia E, Wong SL, Fawcett LK, Bell JL, Visser S, Chen PC, Griffith R, Jaffe A, Sivam S, Vittorio O, Kuyucak S, Waters SA. Q1291H-CFTR molecular dynamics simulations and ex vivo theratyping in nasal epithelial models and clinical response to elexacaftor/tezacaftor/ivacaftor in a Q1291H/F508del patient. Front Mol Biosci 2023; 10:1148501. [PMID: 37325471 PMCID: PMC10267335 DOI: 10.3389/fmolb.2023.1148501] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 05/15/2023] [Indexed: 06/17/2023] Open
Abstract
Background: Cystic fibrosis (CF) is caused by a wide spectrum of mutations in the CF transmembrane conductance regulator (CFTR) gene, with some leading to non-classical clinical presentations. We present an integrated in vivo, in silico and in vitro investigation of an individual with CF carrying the rare Q1291H-CFTR allele and the common F508del allele. At age 56 years, the participant had obstructive lung disease and bronchiectasis, qualifying for Elexacaftor/Tezacaftor/Ivacaftor (ETI) CFTR modulator treatment due to their F508del allele. Q1291H CFTR incurs a splicing defect, producing both a normally spliced but mutant mRNA isoform and a misspliced isoform with a premature termination codon, causing nonsense mediated decay. The effectiveness of ETI in restoring Q1291H-CFTR is largely unknown. Methods: We collected clinical endpoint measurements, including forced expiratory volume in 1 s percent predicted (FEV1pp) and body mass index (BMI), and examined medical history. In silico simulations of the Q1291H-CFTR were compared to Q1291R, G551D, and wild-type (WT)-CFTR. We quantified relative Q1291H CFTR mRNA isoform abundance in patient-derived nasal epithelial cells. Differentiated pseudostratified airway epithelial cell models at air liquid interface were created and ETI treatment impact on CFTR was assessed by electrophysiology assays and Western blot. Results: The participant ceased ETI treatment after 3 months due to adverse events and no improvement in FEV1pp or BMI. In silico simulations of Q1291H-CFTR identified impairment of ATP binding similar to known gating mutants Q1291R and G551D-CFTR. Q1291H and F508del mRNA transcripts composed 32.91% and 67.09% of total mRNA respectively, indicating 50.94% of Q1291H mRNA was misspliced and degraded. Mature Q1291H-CFTR protein expression was reduced (3.18% ± 0.60% of WT/WT) and remained unchanged with ETI. Baseline CFTR activity was minimal (3.45 ± 0.25 μA/cm2) and not enhanced with ETI (5.73 ± 0.48 μA/cm2), aligning with the individual's clinical evaluation as a non-responder to ETI. Conclusion: The combination of in silico simulations and in vitro theratyping in patient-derived cell models can effectively assess CFTR modulator efficacy for individuals with non-classical CF manifestations or rare CFTR mutations, guiding personalized treatment strategies and optimizing clinical outcomes.
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Affiliation(s)
- Katelin M Allan
- School of Clinical Medicine, Discipline of Paediatrics and Child Health, Faculty of Medicine and Health, UNSW Sydney, Sydney, NSW, Australia
- Molecular and Integrative Cystic Fibrosis Research Centre, UNSW Sydney, Sydney, NSW, Australia
- School of Biomedical Sciences, Faculty of Medicine and Health, UNSW Sydney, Sydney, NSW, Australia
| | - Miro A Astore
- School of Physics, The University of Sydney, Sydney, NSW, Australia
| | - Egi Kardia
- School of Clinical Medicine, Discipline of Paediatrics and Child Health, Faculty of Medicine and Health, UNSW Sydney, Sydney, NSW, Australia
- Molecular and Integrative Cystic Fibrosis Research Centre, UNSW Sydney, Sydney, NSW, Australia
- School of Biomedical Sciences, Faculty of Medicine and Health, UNSW Sydney, Sydney, NSW, Australia
| | - Sharon L Wong
- School of Clinical Medicine, Discipline of Paediatrics and Child Health, Faculty of Medicine and Health, UNSW Sydney, Sydney, NSW, Australia
- Molecular and Integrative Cystic Fibrosis Research Centre, UNSW Sydney, Sydney, NSW, Australia
- School of Biomedical Sciences, Faculty of Medicine and Health, UNSW Sydney, Sydney, NSW, Australia
| | - Laura K Fawcett
- School of Clinical Medicine, Discipline of Paediatrics and Child Health, Faculty of Medicine and Health, UNSW Sydney, Sydney, NSW, Australia
- Molecular and Integrative Cystic Fibrosis Research Centre, UNSW Sydney, Sydney, NSW, Australia
- School of Biomedical Sciences, Faculty of Medicine and Health, UNSW Sydney, Sydney, NSW, Australia
- Department of Respiratory Medicine, Sydney Children's Hospital, Sydney, NSW, Australia
| | - Jessica L Bell
- School of Clinical Medicine, Discipline of Paediatrics and Child Health, Faculty of Medicine and Health, UNSW Sydney, Sydney, NSW, Australia
- Children's Cancer Institute, UNSW Sydney, Sydney, NSW, Australia
| | - Simone Visser
- Department of Respiratory Medicine, Royal Prince Alfred Hospital, Sydney, NSW, Australia
| | - Po-Chia Chen
- School of Physics, The University of Sydney, Sydney, NSW, Australia
| | - Renate Griffith
- School of Natural Sciences (Chemistry), University of Tasmania, Hobart, TAS, Australia
| | - Adam Jaffe
- School of Clinical Medicine, Discipline of Paediatrics and Child Health, Faculty of Medicine and Health, UNSW Sydney, Sydney, NSW, Australia
- Molecular and Integrative Cystic Fibrosis Research Centre, UNSW Sydney, Sydney, NSW, Australia
- Department of Respiratory Medicine, Sydney Children's Hospital, Sydney, NSW, Australia
| | - Sheila Sivam
- Department of Respiratory Medicine, Royal Prince Alfred Hospital, Sydney, NSW, Australia
| | - Orazio Vittorio
- School of Biomedical Sciences, Faculty of Medicine and Health, UNSW Sydney, Sydney, NSW, Australia
- Children's Cancer Institute, UNSW Sydney, Sydney, NSW, Australia
| | - Serdar Kuyucak
- School of Physics, The University of Sydney, Sydney, NSW, Australia
| | - Shafagh A Waters
- School of Clinical Medicine, Discipline of Paediatrics and Child Health, Faculty of Medicine and Health, UNSW Sydney, Sydney, NSW, Australia
- Molecular and Integrative Cystic Fibrosis Research Centre, UNSW Sydney, Sydney, NSW, Australia
- School of Biomedical Sciences, Faculty of Medicine and Health, UNSW Sydney, Sydney, NSW, Australia
- Department of Respiratory Medicine, Sydney Children's Hospital, Sydney, NSW, Australia
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Kim YJ, Krainer AR. Antisense Oligonucleotide Therapeutics for Cystic Fibrosis: Recent Developments and Perspectives. Mol Cells 2023; 46:10-20. [PMID: 36697233 PMCID: PMC9880599 DOI: 10.14348/molcells.2023.2172] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 11/22/2022] [Accepted: 11/23/2022] [Indexed: 01/27/2023] Open
Abstract
Antisense oligonucleotide (ASO) technology has become an attractive therapeutic modality for various diseases, including Mendelian disorders. ASOs can modulate the expression of a target gene by promoting mRNA degradation or changing pre-mRNA splicing, nonsense-mediated mRNA decay, or translation. Advances in medicinal chemistry and a deeper understanding of post-transcriptional mechanisms have led to the approval of several ASO drugs for diseases that had long lacked therapeutic options. For instance, an ASO drug called nusinersen became the first approved drug for spinal muscular atrophy, improving survival and the overall disease course. Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene cause cystic fibrosis (CF). Although Trikafta and other CFTR-modulation therapies benefit most CF patients, there is a significant unmet therapeutic need for a subset of CF patients. In this review, we introduce ASO therapies and their mechanisms of action, describe the opportunities and challenges for ASO therapeutics for CF, and discuss the current state and prospects of ASO therapies for CF.
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Affiliation(s)
- Young Jin Kim
- Department of Pediatrics, Mount Sinai Hospital, New York, NY 10029, USA
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Ensinck MM, Carlon MS. One Size Does Not Fit All: The Past, Present and Future of Cystic Fibrosis Causal Therapies. Cells 2022; 11:cells11121868. [PMID: 35740997 PMCID: PMC9220995 DOI: 10.3390/cells11121868] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 05/25/2022] [Accepted: 05/28/2022] [Indexed: 02/04/2023] Open
Abstract
Cystic fibrosis (CF) is the most common monogenic disorder, caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. Over the last 30 years, tremendous progress has been made in understanding the molecular basis of CF and the development of treatments that target the underlying defects in CF. Currently, a highly effective CFTR modulator treatment (Kalydeco™/Trikafta™) is available for 90% of people with CF. In this review, we will give an extensive overview of past and ongoing efforts in the development of therapies targeting the molecular defects in CF. We will discuss strategies targeting the CFTR protein (i.e., CFTR modulators such as correctors and potentiators), its cellular environment (i.e., proteostasis modulation, stabilization at the plasma membrane), the CFTR mRNA (i.e., amplifiers, nonsense mediated mRNA decay suppressors, translational readthrough inducing drugs) or the CFTR gene (gene therapies). Finally, we will focus on how these efforts can be applied to the 15% of people with CF for whom no causal therapy is available yet.
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Affiliation(s)
- Marjolein M. Ensinck
- Molecular Virology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, 3000 Leuven, Flanders, Belgium;
| | - Marianne S. Carlon
- Molecular Virology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, 3000 Leuven, Flanders, Belgium;
- Laboratory of Respiratory Diseases and Thoracic Surgery (BREATHE), Department of Chronic Diseases and Metabolism, KU Leuven, 3000 Leuven, Flanders, Belgium
- Correspondence:
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Integrity and Stability of PTC Bearing CFTR mRNA and Relevance to Future Modulator Therapies in Cystic Fibrosis. Genes (Basel) 2021; 12:genes12111810. [PMID: 34828417 PMCID: PMC8621375 DOI: 10.3390/genes12111810] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/16/2021] [Accepted: 11/18/2021] [Indexed: 12/26/2022] Open
Abstract
Major advances have recently been made in the development and application of CFTR (cystic fibrosis transmembrane conductance regulator) mutation class-specific modulator therapies, but to date, there are no approved modulators for Class I mutations, i.e., those introducing a premature termination codon (PTC) into the CFTR mRNA. Such mutations induce nonsense-mediated decay (NMD), a cellular quality control mechanism that reduces the quantity of PTC bearing mRNAs, presumably to avoid translation of potentially deleterious truncated CFTR proteins. The NMD-mediated reduction of PTC-CFTR mRNA molecules reduces the efficacy of one of the most promising approaches to treatment of such mutations, namely, PTC readthrough therapy, using molecules that induce the incorporation of near-cognate amino acids at the PTC codon, thereby enabling translation of a full-length protein. In this study, we measure the effect of three different PTC mutations on the abundance, integrity, and stability of respective CFTR mRNAs, using CFTR specific RT-qPCR-based assays. Altogether, our data suggest that optimized rescue of PTC mutations has to take into account (1) the different steady-state levels of the CFTR mRNA associated with each specific PTC mutation; (2) differences in abundance between the 3' and 5' regions of CFTR mRNA, even following PTC readthrough or NMD inhibition; and (3) variable effects on CFTR mRNA stability for each specific PTC mutation.
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Mutyam V, Sharma J, Li Y, Peng N, Chen J, Tang LP, Falk Libby E, Singh AK, Conrath K, Rowe SM. Novel Correctors and Potentiators Enhance Translational Readthrough in CFTR Nonsense Mutations. Am J Respir Cell Mol Biol 2021; 64:604-616. [PMID: 33616476 DOI: 10.1165/rcmb.2019-0291oc] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Premature-termination codons (PTCs) in CFTR (cystic fibrosis [CF] transmembrane conductance regulator) result in nonfunctional CFTR protein and are the proximate cause of ∼11% of CF-causing alleles, for which no treatments exist. The CFTR corrector lumacaftor and the potentiator ivacaftor improve CFTR function with terminal PTC mutations and enhance the effect of readthrough agents. Novel correctors GLPG2222 (corrector 1 [C1]), GLPG3221 (corrector 2 [C2]), and potentiator GLPG1837 compare favorably with lumacaftor and ivacaftor in vitro. Here, we evaluated the effect of correctors C1a and C2a (derivatives of C1 and C2) and GLPG1837 alone or in combination with the readthrough compound G418 on CFTR function using heterologous Fischer rat thyroid (FRT) cells, the genetically engineered human bronchial epithelial (HBE) 16HBE14o- cell lines, and primary human cells with PTC mutations. In FRT lines pretreated with G418, GLPG1837 elicited dose-dependent increases in CFTR activity that exceeded those from ivacaftor in FRT-W1282X and FRT-R1162X cells. A three-mechanism strategy consisting of G418, GLPG1837, and two correctors (C1a + C2a) yielded the greatest functional improvements in FRT and 16HBE14o- PTC variants, noting that correction and potentiation without readthrough was sufficient to stimulate CFTR activity for W1282X cells. GLPG1837 + C1a + C2a restored substantial function in G542X/F508del HBE cells and restored even more function for W1282X/F508del cells, largely because of the corrector/potentiator effect, with no additional benefit from G418. In G542X/R553X or R1162X/R1162X organoids, enhanced forskolin-induced swelling was observed with G418 + GLPG1837 + C1a + C2a, although GLPG1837 + C1a + C2a alone was sufficient to improve forskolin-induced swelling in W1282X/W1282X organoids. Combination of CFTR correctors, potentiators, and readthrough compounds augments the functional repair of CFTR nonsense mutations, indicating the potential for novel correctors and potentiators to restore function to truncated W1282X CFTR.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Steven M Rowe
- Department of Medicine.,Department of Pediatrics.,Department of Cell Developmental and Integrative Biology, and.,Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama
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Bergeron C, Cantin AM. New Therapies to Correct the Cystic Fibrosis Basic Defect. Int J Mol Sci 2021; 22:ijms22126193. [PMID: 34201249 PMCID: PMC8227161 DOI: 10.3390/ijms22126193] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 05/31/2021] [Accepted: 06/04/2021] [Indexed: 12/24/2022] Open
Abstract
Rare diseases affect 400 million individuals worldwide and cause significant morbidity and mortality. Finding solutions for rare diseases can be very challenging for physicians and researchers. Cystic fibrosis (CF), a genetic, autosomal recessive, multisystemic, life-limiting disease does not escape this sad reality. Despite phenomenal progress in our understanding of this disease, treatment remains difficult. Until recently, therapies for CF individuals were focused on symptom management. The discovery of the cystic fibrosis transmembrane conductance regulator (CFTR) gene and its product, a protein present at the apical surface of epithelial cells regulating ion transport, allowed the scientific community to learn about the basic defect in CF and to study potential therapies targeting the dysfunctional protein. In the past few years, promising therapies with the goal to restore CFTR function became available and changed the lives of several CF patients. These medications, called CFTR modulators, aim to correct, potentialize, stabilize or amplify CFTR function. Furthermore, research is ongoing to develop other targeted therapies that could be more efficient and benefit a larger proportion of the CF community. The purpose of this review is to summarize our current knowledge of CF genetics and therapies restoring CFTR function, particularly CFTR modulators and gene therapy.
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Affiliation(s)
- Christelle Bergeron
- Department of Medicine, Respiratory Division, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, QC J1H 5N4, Canada;
| | - André M. Cantin
- Department of Medicine, Respiratory Division, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, QC J1H 5N4, Canada;
- Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Respiratory Division, Faculty of Medicine, University of Sherbrooke, 3001, 12e Avenue Nord, Sherbrooke, QC J1H 5N4, Canada
- Correspondence: ; Tel.: +1-819-346-1110 (ext. 14893); Fax: +1-819-564-5377
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Nasal Epithelial Cell-Based Models for Individualized Study in Cystic Fibrosis. Int J Mol Sci 2021; 22:ijms22094448. [PMID: 33923202 PMCID: PMC8123210 DOI: 10.3390/ijms22094448] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 04/22/2021] [Accepted: 04/23/2021] [Indexed: 12/11/2022] Open
Abstract
The emergence of highly effective CFTR modulator therapy has led to significant improvements in health care for most patients with cystic fibrosis (CF). For some, however, these therapies remain inaccessible due to the rarity of their individual CFTR variants, or due to a lack of biologic activity of the available therapies for certain variants. One proposed method of addressing this gap is the use of primary human cell-based models, which allow preclinical therapeutic testing and physiologic assessment of relevant tissue at the individual level. Nasal cells represent one such tissue source and have emerged as a powerful model for individual disease study. The ex vivo culture of nasal cells has evolved over time, and modern nasal cell models are beginning to be utilized to predict patient outcomes. This review will discuss both historical and current state-of-the art use of nasal cells for study in CF, with a particular focus on the use of such models to inform personalized patient care.
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Sharma J, Abbott J, Klaskala L, Zhao G, Birket SE, Rowe SM. A Novel G542X CFTR Rat Model of Cystic Fibrosis Is Sensitive to Nonsense Mediated Decay. Front Physiol 2020; 11:611294. [PMID: 33391025 PMCID: PMC7772197 DOI: 10.3389/fphys.2020.611294] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 11/19/2020] [Indexed: 12/22/2022] Open
Abstract
Nonsense mutations that lead to the insertion of a premature termination codon (PTC) in the cystic fibrosis transmembrane conductance regulator (CFTR) transcript affect 11% of patients with cystic fibrosis (CF) worldwide and are associated with severe disease phenotype. While CF rat models have contributed significantly to our understanding of CF disease pathogenesis, there are currently no rat models available for studying CF nonsense mutations. Here we created and characterized the first homozygous CF rat model that bears the CFTR G542X nonsense mutation in the endogenous locus using CRISPR/Cas9 gene editing. In addition to displaying severe CF manifestations and developmental defects such as reduced growth, abnormal tooth enamel, and intestinal obstruction, CFTR G542X knockin rats demonstrated an absence of CFTR function in tracheal and intestinal sections as assessed by nasal potential difference and transepithelial short-circuit current measurements. Reduced CFTR mRNA levels in the model further suggested sensitivity to nonsense-mediated decay, a pathway elicited by the presence of PTCs that degrades the PTC-bearing transcripts and thus further diminishes the level of CFTR protein. Although functional restoration of CFTR was observed in G542X rat tracheal epithelial cells in response to single readthrough agent therapy, therapeutic efficacy was not observed in G542X knockin rats in vivo. The G542X rat model provides an invaluable tool for the identification and in vivo validation of potential therapies for CFTR nonsense mutations.
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Affiliation(s)
- Jyoti Sharma
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Joseph Abbott
- Horizon Discovery Group, PLC, St. Louis, MO, United States
| | | | - Guojun Zhao
- Horizon Discovery Group, PLC, St. Louis, MO, United States
| | - Susan E. Birket
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Steven M. Rowe
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL, United States
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Silva IAL, Doušová T, Ramalho S, Centeio R, Clarke LA, Railean V, Botelho HM, Holubová A, Valášková I, Yeh JT, Hwang TC, Farinha CM, Kunzelmann K, Amaral MD. Organoids as a personalized medicine tool for ultra-rare mutations in cystic fibrosis: The case of S955P and 1717-2A>G. Biochim Biophys Acta Mol Basis Dis 2020; 1866:165905. [PMID: 32730979 PMCID: PMC7484254 DOI: 10.1016/j.bbadis.2020.165905] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 07/07/2020] [Accepted: 07/22/2020] [Indexed: 12/12/2022]
Abstract
BACKGROUND For most of the >2000 CFTR gene variants reported, neither the associated disease liability nor the underlying basic defect are known, and yet these are essential for disease prognosis and CFTR-based therapeutics. Here we aimed to characterize two ultra-rare mutations - 1717-2A > G (c.1585-2A > G) and S955P (p.Ser955Pro) - as case studies for personalized medicine. METHODS Patient-derived rectal biopsies and intestinal organoids from two individuals with each of these mutations and F508del (p.Phe508del) in the other allele were used to assess CFTR function, response to modulators and RNA splicing pattern. In parallel, we used cellular models to further characterize S955P independently of F508del and to assess its response to CFTR modulators. RESULTS Results in both rectal biopsies and intestinal organoids from both patients evidence residual CFTR function. Further characterization shows that 1717-2A > G leads to alternative splicing generating <1% normal CFTR mRNA and that S955P affects CFTR gating. Finally, studies in organoids predict that both patients are responders to VX-770 alone and even more to VX-770 combined with VX-809 or VX-661, although to different levels. CONCLUSION This study demonstrates the high potential of personalized medicine through theranostics to extend the label of approved drugs to patients with rare mutations.
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Affiliation(s)
- Iris A L Silva
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8 bdg, 1749-016 Lisboa, Portugal
| | - Tereza Doušová
- Department of Pediatrics, 2nd Faculty of Medicine, Charles University and University Hospital Motol, V Uvalu 84,Prague 5, 150 06 Prague, Czech Republic
| | - Sofia Ramalho
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8 bdg, 1749-016 Lisboa, Portugal
| | - Raquel Centeio
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8 bdg, 1749-016 Lisboa, Portugal
| | - Luka A Clarke
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8 bdg, 1749-016 Lisboa, Portugal
| | - Violeta Railean
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8 bdg, 1749-016 Lisboa, Portugal
| | - Hugo M Botelho
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8 bdg, 1749-016 Lisboa, Portugal
| | - Andrea Holubová
- Department of Biology and Medical Genetics, 2nd Faculty of Medicine, Charles University and University Hospital Motol, V Uvalu 84,Prague 5, 150 06 Prague, Czech Republic
| | - Iveta Valášková
- Department of Medical Genetics, Masaryk University Brno and University Hospital Brno, Jihlavská 20, Brno 625 00, Czech Republic
| | - Jiunn-Tyng Yeh
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, United States of America
| | - Tzyh-Chang Hwang
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, United States of America
| | - Carlos M Farinha
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8 bdg, 1749-016 Lisboa, Portugal
| | - Karl Kunzelmann
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Margarida D Amaral
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8 bdg, 1749-016 Lisboa, Portugal.
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Novel frameshift variant of the CFTR gene: S511Lfs*2 from phenotype to molecular predictions. Mol Biol Rep 2020; 47:6463-6469. [DOI: 10.1007/s11033-020-05677-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 07/09/2020] [Accepted: 07/19/2020] [Indexed: 11/28/2022]
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Lopes-Pacheco M. CFTR Modulators: The Changing Face of Cystic Fibrosis in the Era of Precision Medicine. Front Pharmacol 2020; 10:1662. [PMID: 32153386 PMCID: PMC7046560 DOI: 10.3389/fphar.2019.01662] [Citation(s) in RCA: 275] [Impact Index Per Article: 68.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 12/19/2019] [Indexed: 12/22/2022] Open
Abstract
Cystic fibrosis (CF) is a lethal inherited disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene, which result in impairment of CFTR mRNA and protein expression, function, stability or a combination of these. Although CF leads to multifaceted clinical manifestations, the respiratory disorder represents the major cause of morbidity and mortality of these patients. The life expectancy of CF patients has substantially lengthened due to early diagnosis and improvements in symptomatic therapeutic regimens. Quality of life remains nevertheless limited, as these individuals are subjected to considerable clinical, psychosocial and economic burdens. Since the discovery of the CFTR gene in 1989, tremendous efforts have been made to develop therapies acting more upstream on the pathogenesis cascade, thereby overcoming the underlying dysfunctions caused by CFTR mutations. In this line, the advances in cell-based high-throughput screenings have been facilitating the fast-tracking of CFTR modulators. These modulator drugs have the ability to enhance or even restore the functional expression of specific CF-causing mutations, and they have been classified into five main groups depending on their effects on CFTR mutations: potentiators, correctors, stabilizers, read-through agents, and amplifiers. To date, four CFTR modulators have reached the market, and these pharmaceutical therapies are transforming patients' lives with short- and long-term improvements in clinical outcomes. Such breakthroughs have paved the way for the development of novel CFTR modulators, which are currently under experimental and clinical investigations. Furthermore, recent insights into the CFTR structure will be useful for the rational design of next-generation modulator drugs. This review aims to provide a summary of recent developments in CFTR-directed therapeutics. Barriers and future directions are also discussed in order to optimize treatment adherence, identify feasible and sustainable solutions for equitable access to these therapies, and continue to expand the pipeline of novel modulators that may result in effective precision medicine for all individuals with CF.
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Affiliation(s)
- Miquéias Lopes-Pacheco
- Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisbon, Lisbon, Portugal
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Sharma N, Cutting GR. The genetics and genomics of cystic fibrosis. J Cyst Fibros 2019; 19 Suppl 1:S5-S9. [PMID: 31879237 DOI: 10.1016/j.jcf.2019.11.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 11/06/2019] [Accepted: 11/08/2019] [Indexed: 02/07/2023]
Abstract
Genetics is the branch of biology concerned with study of individual genes and how they work whereas genomics is involved with the analysis of all genes and their interactions. Both of these approaches have been applied extensively to CF. Identification of the CFTR gene initiated the dissection of CF genetics at the molecular level. Subsequently, thousands of variants were found in the gene and the functional consequences of a subset have been studied in detail. The completion of the human genome ushered in a new phase of study where the role of genes beyond CFTR could be evaluated for their contribution to the severity of CF. This will be a brief overview of the contribution of these complementary methods to our understanding of CF pathogenesis.
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Affiliation(s)
- N Sharma
- Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - G R Cutting
- Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America.
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Phuan PW, Tan JA, Rivera AA, Zlock L, Nielson DW, Finkbeiner WE, Haggie PM, Verkman AS. Nanomolar-potency 'co-potentiator' therapy for cystic fibrosis caused by a defined subset of minimal function CFTR mutants. Sci Rep 2019; 9:17640. [PMID: 31776420 PMCID: PMC6881293 DOI: 10.1038/s41598-019-54158-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 11/07/2019] [Indexed: 12/11/2022] Open
Abstract
Available CFTR modulators provide no therapeutic benefit for cystic fibrosis (CF) caused by many loss-of-function mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel, including N1303K. We previously introduced the concept of ‘co-potentiators’ (combination-potentiators) to rescue CFTR function in some minimal function CFTR mutants. Herein, a screen of ~120,000 drug-like synthetic small molecules identified active co-potentiators of pyrazoloquinoline, piperidine-pyridoindole, tetrahydroquinoline and phenylazepine classes, with EC50 down to ~300 nM following initial structure-activity studies. Increased CFTR chloride conductance by up to 8-fold was observed when a co-potentiator (termed ‘Class II potentiator’) was used with a classical potentiator (‘Class I potentiator’) such as VX-770 or GLPG1837. To investigate the range of CFTR mutations benefitted by co-potentiators, 14 CF-associated CFTR mutations were studied in transfected cell models. Co-potentiator efficacy was found for CFTR missense, deletion and nonsense mutations in nucleotide binding domain-2 (NBD2), including W1282X, N1303K, c.3700A > G and Q1313X (with corrector for some mutations). In contrast, CFTR mutations G85E, R334W, R347P, V520F, R560T, A561E, M1101K and R1162X showed no co-potentiator activity, even with corrector. Co-potentiator efficacy was confirmed in primary human bronchial epithelial cell cultures generated from a N1303K homozygous CF subject. The Class II potentiators identified here may have clinical benefit for CF caused by mutations in the NBD2 domain of CFTR.
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Affiliation(s)
- Puay-Wah Phuan
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA.
| | - Joseph-Anthony Tan
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Amber A Rivera
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Lorna Zlock
- Department of Pathology, University of California, San Francisco, San Francisco, CA, USA
| | - Dennis W Nielson
- Department of Pediatrics, University of California, San Francisco, San Francisco, CA, USA
| | - Walter E Finkbeiner
- Department of Pathology, University of California, San Francisco, San Francisco, CA, USA
| | - Peter M Haggie
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Alan S Verkman
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA.,Department of Physiology, University of California, San Francisco, San Francisco, CA, USA
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Mutation-specific dual potentiators maximize rescue of CFTR gating mutants. J Cyst Fibros 2019; 19:236-244. [PMID: 31678009 DOI: 10.1016/j.jcf.2019.10.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 10/04/2019] [Accepted: 10/08/2019] [Indexed: 12/14/2022]
Abstract
BACKGROUND The potentiator ivacaftor (VX-770) has been approved for therapy of 38 cystic fibrosis (CF) mutations (∼10% of the patient population) associated with a gating defect of the CF transmembrane conductance regulator (CFTR). Despite the success of VX-770 treatment of patients carrying at least one allele of the most common gating mutation G551D-CFTR, some lung function decline and P. aeruginosa colonization persist. This study aims at identifying potentiator combinations that can considerably enhance the limited channel activity of a panel of CFTR gating mutants over monotherapy. METHODS The functional response of 13 CFTR mutants to single potentiators or systematic potentiator combinations was determined in the human bronchial epithelial cell line CFBE41o- and a subset of them was confirmed in primary human nasal epithelia (HNE). RESULTS In six out of thirteen CFTR missense mutants the fractional plasma membrane (PM) activity, a surrogate measure of CFTR channel gating, reached only ∼10-50% of WT channel activity upon VX-770 treatment, indicating incomplete gating correction. Combinatorial potentiator profiling and cluster analysis of mutant responses to 24 diverse investigational potentiators identified several compound pairs that improved the gating activity of R352Q-, S549R-, S549N-, G551D-, and G1244E-CFTR to ∼70-120% of the WT. Similarly, the potentiator combinations were able to confer WT-like function to G551D-CFTR in patient-derived human nasal epithelia. CONCLUSION This study suggests that half of CF patients with missense mutations approved for VX-770 administration, could benefit from the development of dual potentiator therapy.
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