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Gao J, Ververi A, Thompson E, Tryon R, Sotiriadis A, Rouvalis F, Grange DK, Giannios C, Nichols CG. A novel ABCC9 variant in a Greek family with Cantu syndrome affecting multiple generations highlights the functional role of the SUR2B NBD1. Am J Med Genet A 2024:e63815. [PMID: 39031464 DOI: 10.1002/ajmg.a.63815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2024] [Revised: 06/26/2024] [Accepted: 06/28/2024] [Indexed: 07/22/2024]
Abstract
Cantu syndrome (CS) (OMIM #239850) is an autosomal dominant multiorgan system condition, associated with a characteristic facial phenotype, hypertrichosis, and multiple cardiovascular complications. CS is caused by gain-of-function (GOF) variants in KCNJ8 or ABCC9 that encode pore-forming Kir6.1 and regulatory SUR2 subunits of ATP-sensitive potassium (KATP) channels. A novel heterozygous ABCC9 variant, c.2440G>T; p.Gly814Trp, was identified in three individuals from a four generation Greek family. The membrane potential in cells stably expressing hKir6.1 and hSUR2B with p.Gly814Trp was hyperpolarized compared to cells expressing WT channels, and inside-out patch-clamp assays of KATP channels formed with hSUR2B p.Gly814Trp demonstrated a decreased sensitivity to ATP inhibition, confirming a relatively mild GOF effect of this variant. The specific location of the variant reveals an unrecognized functional role of the first glycine in the signature motif of the nucleotide binding domains in ATP-binding cassette (ABC) protein ion channels.
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Affiliation(s)
- Jian Gao
- Department of Cell Biology and Physiology, Washington University in St. Louis, St. Louis, Missouri, USA
- Center for the Investigation of Membrane Excitability Diseases, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Athina Ververi
- Department for Genetics of Rare Diseases, Papageorgiou General Hospital, Thessaloniki, Greece
| | - Ellen Thompson
- Department of Cell Biology and Physiology, Washington University in St. Louis, St. Louis, Missouri, USA
- Center for the Investigation of Membrane Excitability Diseases, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Rob Tryon
- Department of Cell Biology and Physiology, Washington University in St. Louis, St. Louis, Missouri, USA
- Center for the Investigation of Membrane Excitability Diseases, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Alexandros Sotiriadis
- Second Department of Obstetrics and Gynecology, Aristotle University of Thessaloniki, Ippokrateio Hospital, Thessaloniki, Greece
| | | | - Dorothy K Grange
- Center for the Investigation of Membrane Excitability Diseases, Washington University in St. Louis, St. Louis, Missouri, USA
- Department of Pediatrics, Division of Genetics and Genomic Medicine, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Christos Giannios
- Department of Developmental Paediatrics, Naval Hospital of Athens, Athens, Greece
| | - Colin G Nichols
- Department of Cell Biology and Physiology, Washington University in St. Louis, St. Louis, Missouri, USA
- Center for the Investigation of Membrane Excitability Diseases, Washington University in St. Louis, St. Louis, Missouri, USA
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Morais P, Zhang R, Yu YT. Therapeutic Nonsense Suppression Modalities: From Small Molecules to Nucleic Acid-Based Approaches. Biomedicines 2024; 12:1284. [PMID: 38927491 PMCID: PMC11201248 DOI: 10.3390/biomedicines12061284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Revised: 05/29/2024] [Accepted: 06/07/2024] [Indexed: 06/28/2024] Open
Abstract
Nonsense mutations are genetic mutations that create premature termination codons (PTCs), leading to truncated, defective proteins in diseases such as cystic fibrosis, neurofibromatosis type 1, Dravet syndrome, Hurler syndrome, Beta thalassemia, inherited bone marrow failure syndromes, Duchenne muscular dystrophy, and even cancer. These mutations can also trigger a cellular surveillance mechanism known as nonsense-mediated mRNA decay (NMD) that degrades the PTC-containing mRNA. The activation of NMD can attenuate the consequences of truncated, defective, and potentially toxic proteins in the cell. Since approximately 20% of all single-point mutations are disease-causing nonsense mutations, it is not surprising that this field has received significant attention, resulting in a remarkable advancement in recent years. In fact, since our last review on this topic, new examples of nonsense suppression approaches have been reported, namely new ways of promoting the translational readthrough of PTCs or inhibiting the NMD pathway. With this review, we update the state-of-the-art technologies in nonsense suppression, focusing on novel modalities with therapeutic potential, such as small molecules (readthrough agents, NMD inhibitors, and molecular glue degraders); antisense oligonucleotides; tRNA suppressors; ADAR-mediated RNA editing; targeted pseudouridylation; and gene/base editing. While these various modalities have significantly advanced in their development stage since our last review, each has advantages (e.g., ease of delivery and specificity) and disadvantages (manufacturing complexity and off-target effect potential), which we discuss here.
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Affiliation(s)
- Pedro Morais
- Drug Metabolism and Pharmacokinetics, Research and Development, Bayer Pharmaceuticals, 42113 Wuppertal, Germany
| | - Rui Zhang
- Center for RNA Biology, Department of Biochemistry and Biophysics, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA;
| | - Yi-Tao Yu
- Center for RNA Biology, Department of Biochemistry and Biophysics, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA;
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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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4
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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] [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] [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. MOLECULAR THERAPY. 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] [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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