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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Cao L, Wu Y, Gong Y, Zhou Q. Small molecule modulators of cystic fibrosis transmembrane conductance regulator (CFTR): Structure, classification, and mechanisms. Eur J Med Chem 2024; 265:116120. [PMID: 38194776 DOI: 10.1016/j.ejmech.2023.116120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Revised: 12/28/2023] [Accepted: 12/31/2023] [Indexed: 01/11/2024]
Abstract
The advent of small molecule modulators targeting the cystic fibrosis transmembrane conductance regulator (CFTR) has revolutionized the treatment of persons with cystic fibrosis (CF) (pwCF). Presently, these small molecule CFTR modulators have gained approval for usage in approximately 90 % of adult pwCF. Ongoing drug development endeavors are focused on optimizing the therapeutic benefits while mitigating potential adverse effects associated with this treatment approach. Based on their mode of interaction with CFTR, these drugs can be classified into two distinct categories: specific CFTR modulators and non-specific CFTR modulators. Specific CFTR modulators encompass potentiators and correctors, whereas non-specific CFTR modulators encompass activators, proteostasis modulators, stabilizers, reader-through agents, and amplifiers. Currently, four small molecule modulators, all classified as potentiators and correctors, have obtained marketing approval. Furthermore, numerous novel small molecule modulators, exhibiting diverse mechanisms of action, are currently undergoing development. This review aims to explore the classification, mechanisms of action, molecular structures, developmental processes, and interrelationships among small molecule CFTR modulators.
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Affiliation(s)
- Luyang Cao
- China Pharmaceutical University, Nanjing, 210009, PR China
| | - Yong Wu
- Jiangsu Vcare PharmaTech Co., Ltd., Huakang Road 136, Biotech and Pharmaceutical Valley, Jiangbei New Area, Nanjing, 211800, PR China
| | - Yanchun Gong
- Jiangsu Vcare PharmaTech Co., Ltd., Huakang Road 136, Biotech and Pharmaceutical Valley, Jiangbei New Area, Nanjing, 211800, PR China.
| | - Qingfa Zhou
- China Pharmaceutical University, Nanjing, 210009, PR China.
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Chen JL, Leeder WM, Morais P, Adachi H, Yu YT. Pseudouridylation-mediated gene expression modulation. Biochem J 2024; 481:1-16. [PMID: 38174858 DOI: 10.1042/bcj20230096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Revised: 12/13/2023] [Accepted: 12/19/2023] [Indexed: 01/05/2024]
Abstract
RNA-guided pseudouridylation, a widespread post-transcriptional RNA modification, has recently gained recognition for its role in cellular processes such as pre-mRNA splicing and the modulation of premature termination codon (PTC) readthrough. This review provides insights into its mechanisms, functions, and potential therapeutic applications. It examines the mechanisms governing RNA-guided pseudouridylation, emphasizing the roles of guide RNAs and pseudouridine synthases in catalyzing uridine-to-pseudouridine conversion. A key focus is the impact of RNA-guided pseudouridylation of U2 small nuclear RNA on pre-mRNA splicing, encompassing its influence on branch site recognition and spliceosome assembly. Additionally, the review discusses the emerging role of RNA-guided pseudouridylation in regulating PTC readthrough, impacting translation termination and genetic disorders. Finally, it explores the therapeutic potential of pseudouridine modifications, offering insights into potential treatments for genetic diseases and cancer and the development of mRNA vaccine.
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Affiliation(s)
- Jonathan L Chen
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester Medical Center, Rochester, NY, U.S.A
| | | | | | - Hironori Adachi
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester Medical Center, Rochester, NY, U.S.A
| | - Yi-Tao Yu
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester Medical Center, Rochester, NY, U.S.A
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Blomquist VG, Niu J, Choudhury P, Al Saneh A, Colecraft HM, Ahern CA. Transfer RNA-mediated restoration of potassium current and electrical correction in premature termination long-QT syndrome hERG mutants. Mol Ther Nucleic Acids 2023; 34:102032. [PMID: 37842167 PMCID: PMC10568093 DOI: 10.1016/j.omtn.2023.102032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 09/14/2023] [Indexed: 10/17/2023]
Abstract
Disease-causing premature termination codons (PTCs) individually disrupt the functional expression of hundreds of genes and represent a pernicious clinical challenge. In the heart, loss-of-function mutations in the hERG potassium channel account for approximately 30% of long-QT syndrome arrhythmia, a lethal cardiac disorder with limited treatment options. Premature termination of ribosomal translation produces a truncated and, for potassium channels, a potentially dominant-negative protein that impairs the functional assembly of the wild-type homotetrameric hERG channel complex. We used high-throughput flow cytometry and patch-clamp electrophysiology to assess the trafficking and voltage-dependent activity of hERG channels carrying patient PTC variants that have been corrected by anticodon engineered tRNA. Adenoviral-mediated expression of mutant hERG channels in cultured adult guinea pig cardiomyocytes prolonged action potential durations, and this deleterious effect was corrected upon adenoviral delivery of a human ArgUGA tRNA to restore full-length hERG protein. The results demonstrate mutation-specific, context-agnostic PTC correction and elevate the therapeutic potential of this approach for rare genetic diseases caused by stop codons.
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Affiliation(s)
- Viggo G. Blomquist
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, NY 10032, USA
| | - Jacqueline Niu
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, NY 10032, USA
| | - Papiya Choudhury
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, NY 10032, USA
| | - Ahmad Al Saneh
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, IA, USA
| | - Henry M. Colecraft
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, NY 10032, USA
| | - Christopher A. Ahern
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, IA, USA
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