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Solomon GM, Linnemann RW, Rich R, Streby A, Buehler B, Hunter E, Vijaykumar K, Hunt WR, Brewington JJ, Rab A, Bai SP, Westbrook AL, McNicholas-Bevensee C, Hong J, Manfredi C, Barilla C, Suzuki S, Davis BR, Sorscher EJ. Evaluation of elexacaftor-tezacaftor-ivacaftor treatment in individuals with cystic fibrosis and CFTR N1303K in the USA: a prospective, multicentre, open-label, single-arm trial. THE LANCET. RESPIRATORY MEDICINE 2024:S2213-2600(24)00205-4. [PMID: 39208836 DOI: 10.1016/s2213-2600(24)00205-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 06/13/2024] [Accepted: 06/14/2024] [Indexed: 09/04/2024]
Abstract
BACKGROUND CFTR modulators are approved for approximately 90% of people with cystic fibrosis in the USA and provide substantial clinical benefit. N1303K (Asn1303Lys), one of the most common class 2 CFTR defects, has not been approved for these therapies by any regulatory agency. Preclinical investigation by our laboratories showed N1303K CFTR activation with elexacaftor-tezacaftor-ivacaftor (ETI). In this trial, we evaluate whether ETI improves CFTR function, measured by sweat chloride and other clinical outcomes, in people with cystic fibrosis and CFTRN1303K. METHODS In this prospective, open-label, single-arm trial, participants aged 12 years or older with cystic fibrosis encoding at least one N1303K variant and at least one CFTRN1303K allele who were ineligible for modulator therapy by US Food and Drug Administration labelling were given ETI for 28 days followed by a 28-day washout period at two cystic fibrosis centres in the USA. Participants received two orally administered pills of 100 mg elexacaftor, 50 mg tezacaftor, and 75 mg ivacaftor once daily in the morning, and 150 mg ivacaftor once daily in the evening. The primary endpoint was mean change in sweat chloride from baseline up to day 28 compared with mixed-effects models. Secondary endpoints were changes in percentage of predicted FEV1 (ppFEV1), Cystic Fibrosis Questionnaire-Revised (CFQ-R) respiratory domain, BMI, and weight after ETI therapy. Safety was assessed in all participants who received at least one dose of the study drug and primary and secondary analyses were performed in all participants who took the study drug per protocol. The trial was registered at ClinicalTrials.gov (NCT03506061) and remains open for reporting purposes. FINDINGS Between June 7, 2022, and Oct 20, 2023, 20 participants (ten male and ten female) were enrolled and received ETI treatment. One participant was lost to follow-up but was included in intention-to-treat analyses. At 28 days, the mean sweat chloride reduction was -1·1 mmol/L (95% CI -5·3 to 3·1; p=0·61) with only one participant showing a sweat chloride decrease greater than 15 mmol/L. There was a mean increase in ppFEV1 from baseline at day 28 of 9·5 percentage points (6·7-12·3; p<0·0001) with 15 (75%) participants showing at least a 5% increase in ppFEV1. Improvements were also identified in mean CFQ-R respiratory domain score (20·8 increase [95% CI 11·9-29·8]; p<0·0001), BMI (0·4 kg/m2 increase [0·2-0·7]; p=0·0017), and weight (1·0 kg increase [0·4-1·7]; p=0·0020) after 28 days of ETI treatment. 14 (70%) of 20 participants had adverse events (12 [60%] mild, one [5%] moderate), with one (5%) serious adverse event of hospitalisation attributed to pneumonia. No deaths were recorded in the study. INTERPRETATION Individuals with CFTRN1303K showed no change in sweat chloride after 28 days of treatment with ETI. However, there were improvements in secondary clinical endpoints, which suggest clinical efficacy. Our approach provides support for the use of in vitro model systems to inform clinical trials for rare CFTR variants. FUNDING The Cystic Fibrosis Foundation and the US National Institutes of Health.
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Affiliation(s)
| | - Rachel W Linnemann
- Emory University, Atlanta, GA, USA; Children's Healthcare of Atlanta, Atlanta, GA, USA
| | - Rachel Rich
- University of Alabama at Birmingham, Birmingham, AL, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | - Cristina Barilla
- University of Alabama at Birmingham, Birmingham, AL, USA; University of Texas Health Science Center, Houston, TX, USA
| | - Shingo Suzuki
- University of Alabama at Birmingham, Birmingham, AL, USA; University of Texas Health Science Center, Houston, TX, USA
| | - Brian R Davis
- University of Alabama at Birmingham, Birmingham, AL, USA; University of Texas Health Science Center, Houston, TX, USA
| | - Eric J Sorscher
- Emory University, Atlanta, GA, USA; Children's Healthcare of Atlanta, Atlanta, GA, USA
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Burgel PR, Sermet-Gaudelus I, Girodon E, Durieu I, Houdouin V, Audousset C, Macey J, Grenet D, Porzio M, Murris-Espin M, Reix P, Baravalle M, Belleguic C, Mely L, Verhille J, Weiss L, Reynaud-Gaubert M, Mittaine M, Hamidfar R, Ramel S, Cosson L, Douvry B, Danner-Boucher I, Foucaud P, Roy C, Burnet E, Raynal C, Audrezet MP, Da Silva J, Martin C. The expanded French compassionate programme for elexacaftor-tezacaftor-ivacaftor use in people with cystic fibrosis without a F508del CFTR variant: a real-world study. THE LANCET. RESPIRATORY MEDICINE 2024:S2213-2600(24)00208-X. [PMID: 39151434 DOI: 10.1016/s2213-2600(24)00208-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Revised: 06/20/2024] [Accepted: 06/21/2024] [Indexed: 08/19/2024]
Abstract
BACKGROUND Elexacaftor-tezacaftor-ivacaftor has been approved in Europe for people with cystic fibrosis with at least one F508del CFTR variant. Additionally, it is approved by the US Food and Drug Administration (FDA) for people with cystic fibrosis with at least one of 177 rare variants. The aims of this study were to describe the clinical response to elexacaftor-tezacaftor-ivacaftor for people with cystic fibrosis without a F508del CFTR variant in France and to determine CFTR variant responsiveness to elexacaftor-tezacaftor-ivacaftor based on the observed clinical response. METHODS The French compassionate programme expanded access to elexacaftor-tezacaftor-ivacaftor to people with cystic fibrosis, aged 6 years and older, without a F508del variant, excluding those with two variants previously characterised as non-responsive. Participants at France's 47 cystic fibrosis centres were given a 4-6 week trial of elexacaftor-tezacaftor-ivacaftor and response was determined by a centralised committee based on evolution of clinical data, lung function, and sweat chloride concentration. Responsiveness of individual CFTR variants was derived from observed clinical responses. FINDINGS The first compassionnate programme was launched on May 19, 2022; by March 8, 2024, 516 people with cystic fibrosis had been identified for inclusion in this real-word study: 37 were not included due to the presence of two variants previously characterised as non-responsive to elexacaftor-tezacaftor-ivacaftor, and 479 (229 females [48%] and 250 males [52%]) received elexacaftor-tezacaftor-ivacaftor for 4-6 weeks. Among 443 participants who received no CFTR modulator before elexacaftor-tezacaftor-ivacaftor, 83 had at least one FDA-approved variant, of whom 81 (98%) were responders and continued elexacaftor-tezacaftor-ivacaftor; in responders, mean absolute change in sweat chloride was -44·5 mmol/L (95% CI -39·1 to -49·8) and percentage of predicted FEV1 (ppFEV1) was 11·1 percentage points (95% CI 8·4 to 13·7; both comparisons p<0·0001). Among 360 participants with no FDA-approved variant and no previous CFTR modulator, 177 (49%) were responders; in responders, mean absolute change in sweat chloride was -20·5 mmol/L (-17·2 to -23·8) and ppFEV1 was 13·2 percentage points (11·4 to 15·0; both comparisons p<0·0001). Among 36 participants who were receiving ivacaftor before elexacaftor-tezacaftor-ivacaftor, 32 (89%) continued elexacaftor-tezacaftor-ivacaftor. Of 251 individual CFTR variants, 64 (28 FDA-approved) were classified as responsive or possibly responsive to elexacaftor-tezacaftor-ivacaftor, and 123 (two FDA-approved) as non-responsive or possibly non-responsive to elexacaftor-tezacaftor-ivacaftor. INTERPRETATION In France, over half of the population with cystic fibrosis without a F508del variant responded to elexacaftor-tezacaftor-ivacaftor, with most responders having no FDA-approved variant. The treatment period was relatively short and further research is warranted to describe the long-term safety and effectiveness of elexacaftor-tezacaftor-ivacaftor in this population. FUNDING Association Vaincre la Mucoviscidose, Société Française de la Mucoviscidose, and Filière Maladies Rares MUCO-CFTR.
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Affiliation(s)
- Pierre-Régis Burgel
- Université Paris-Cité, Institut Cochin, CNRS, INSERM, Paris, France; Respiratory Medicine and Cystic Fibrosis National Reference Center, Hôpital Cochin, AP-HP, Paris, France; ERN-Lung CF network, Frankfurt, Germany.
| | - Isabelle Sermet-Gaudelus
- ERN-Lung CF network, Frankfurt, Germany; Centre de Référence Maladies Rares, Mucoviscidose et Affections Liées à CFTR, Pneumologie Pédiatrique et Allergologie, Hôpital Necker Enfants Malades, AP-HP, Paris, France; Université Paris-Cité, Institut Necker Enfants Malades, INSERM U1151, Paris, France
| | - Emmanuelle Girodon
- Centre-Université Paris-Cité, Service de Médecine Génomique des Maladies de Système et d'Organe, Hôpital Cochin, AP-HP, Paris, France
| | - Isabelle Durieu
- ERN-Lung CF network, Frankfurt, Germany; Centre de Référence Adulte de la Mucoviscidose, Service de Médecine Interne, Hospices Civils de Lyon, Pierre Bénite, France; Université de Lyon, Research on Healthcare Performance, INSERM U1290, Lyon, France
| | - Véronique Houdouin
- Centre de Ressources et de Compétence pour la Mucoviscidose, Centre Hospitalier Universitaire Robert Debré, AP-HP, Paris, France
| | - Camille Audousset
- Centre de Ressources et de Compétences Calmette, Centre Hospitalier Universitaire de Lille, Université de Lille, Lille, France; University of Lille, CHU Lille, INSERM, CNRS, Institut Pasteur de Lille, U1019, UMR 9017, Center for Infection and Immunity of Lille, Lille, France
| | - Julie Macey
- Respiratory Medicine and Cystic Fibrosis Center, CHU de Bordeaux, Bordeaux, France
| | - Dominique Grenet
- Centre de Transplantation Pulmonaire. Service de Pneumologie, Hôpital Foch, Suresnes, France
| | - Michele Porzio
- Department of Respiratory Medicine and Cystic Fibrosis Center, Federation of Translational Medicine of Strasbourg, University Hospitals, Strasbourg, France
| | - Marlène Murris-Espin
- Cystic Fibrosis Center Service de Pneumologie Pôle des Voies Respiratoires, Hôpital Larrey CHU de Toulouse, Toulouse, France
| | - Philippe Reix
- Centre de Ressources et de Compétence de la Mucoviscidose Pédiatrique, Hospices Civils de Lyon, Bron, France
| | - Mélisande Baravalle
- Centre de Ressources et de Compétence de la Mucoviscidose, Hôpital de la Timone, Marseille, France
| | - Chantal Belleguic
- Université de Rennes, CHU Rennes, Department of Respiratory Medicine, Rennes, France
| | - Laurent Mely
- Hôpital Renée Sabran, Cystic Fibrosis Center, Giens, France
| | - Juliette Verhille
- Centre Hospitalier Universitaire Félix Guyon, Saint Denis, La Réunion, France
| | - Laurence Weiss
- Centre de Ressources et de Compétence de la Mucoviscidose Pédiatrique, CHU, Strasbourg, France
| | - Martine Reynaud-Gaubert
- Department of Respiratory Medicine and Lung Transplantation, Aix Marseille Université, AP-HM, Hôpital Nord, Marseille, France
| | | | - Rebecca Hamidfar
- Service Hospitalo-Universitaire de Pneumologie et Physiologie, Pôle Thorax et Vaisseaux, Centre hospitalier universitaire de Grenoble-Alpes, La Tronche, France
| | - Sophie Ramel
- Centre de Ressources et de Compétences de la Mucoviscidose, Fondation Ildys, Roscoff, France
| | - Laure Cosson
- Centre de Mucoviscidose, Service de Pneumologie et Immuno-Allergologie, Hôpital de la Mucoviscidose Pédiatrique, CHU, Tours, France
| | - Benoit Douvry
- Service de Pneumologie, Centre Hospitalier Intercommunal, FHU SENEC, Créteil, France
| | | | | | - Charlotte Roy
- Centre de Référence Maladies Rares, Mucoviscidose et Affections Liées à CFTR, Pneumologie Pédiatrique et Allergologie, Hôpital Necker Enfants Malades, AP-HP, Paris, France
| | - Espérie Burnet
- Respiratory Medicine and Cystic Fibrosis National Reference Center, Hôpital Cochin, AP-HP, Paris, France; ERN-Lung CF network, Frankfurt, Germany
| | - Caroline Raynal
- Génétique Moléculaire, CHU Montpellier, Montpellier, France; PhyMedExp, INSERM, CNRS UMR, Montpellier, France
| | - Marie-Pierre Audrezet
- Service de Génétique Moléculaire, CHRU Brest, Brest, France; Université de Brest, INSERM, UMR 1078, GGB, Brest, France
| | - Jennifer Da Silva
- Respiratory Medicine and Cystic Fibrosis National Reference Center, Hôpital Cochin, AP-HP, Paris, France; ERN-Lung CF network, Frankfurt, Germany
| | - Clémence Martin
- Université Paris-Cité, Institut Cochin, CNRS, INSERM, Paris, France; Respiratory Medicine and Cystic Fibrosis National Reference Center, Hôpital Cochin, AP-HP, Paris, France; ERN-Lung CF network, Frankfurt, Germany
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Bihler H, Sivachenko A, Millen L, Bhatt P, Patel AT, Chin J, Bailey V, Musisi I, LaPan A, Allaire NE, Conte J, Simon NR, Magaret AS, Raraigh KS, Cutting GR, Skach WR, Bridges RJ, Thomas PJ, Mense M. In vitro modulator responsiveness of 655 CFTR variants found in people with cystic fibrosis. J Cyst Fibros 2024; 23:664-675. [PMID: 38388235 DOI: 10.1016/j.jcf.2024.02.006] [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: 07/28/2023] [Revised: 02/04/2024] [Accepted: 02/14/2024] [Indexed: 02/24/2024]
Abstract
BACKGROUND In 2017, the US Food and Drug Administration initiated expansion of drug labels for the treatment of cystic fibrosis (CF) to include CF transmembrane conductance regulator (CFTR) gene variants based on in vitro functional studies. This study aims to identify CFTR variants that result in increased chloride (Cl-) transport function by the CFTR protein after treatment with the CFTR modulator combination elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA). These data may benefit people with CF (pwCF) who are not currently eligible for modulator therapies. METHODS Plasmid DNA encoding 655 CFTR variants and wild-type (WT) CFTR were transfected into Fisher Rat Thyroid cells that do not natively express CFTR. After 24 h of incubation with control or TEZ and ELX, and acute addition of IVA, CFTR function was assessed using the transepithelial current clamp conductance assay. Each variant's forskolin/cAMP-induced baseline Cl- transport activity, responsiveness to IVA alone, and responsiveness to the TEZ/ELX/IVA combination were measured in three different laboratories. Western blots were conducted to evaluate CFTR protein maturation and complement the functional data. RESULTS AND CONCLUSIONS 253 variants not currently approved for CFTR modulator therapy showed low baseline activity (<10 % of normal CFTR Cl- transport activity). For 152 of these variants, treatment with ELX/TEZ/IVA improved the Cl- transport activity by ≥10 % of normal CFTR function, which is suggestive of clinical benefit. ELX/TEZ/IVA increased CFTR function by ≥10 percentage points for an additional 140 unapproved variants with ≥10 % but <50 % of normal CFTR function at baseline. These findings significantly expand the number of rare CFTR variants for which ELX/TEZ/IVA treatment should result in clinical benefit.
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Affiliation(s)
- Hermann Bihler
- CFFT Lab, Cystic Fibrosis Foundation, Lexington, MA 02421, USA
| | | | - Linda Millen
- University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Priyanka Bhatt
- CFFT Lab, Cystic Fibrosis Foundation, Lexington, MA 02421, USA
| | | | - Justin Chin
- CFFT Lab, Cystic Fibrosis Foundation, Lexington, MA 02421, USA
| | - Violaine Bailey
- CFFT Lab, Cystic Fibrosis Foundation, Lexington, MA 02421, USA
| | - Isaac Musisi
- CFFT Lab, Cystic Fibrosis Foundation, Lexington, MA 02421, USA
| | - André LaPan
- CFFT Lab, Cystic Fibrosis Foundation, Lexington, MA 02421, USA
| | | | - Joshua Conte
- CFFT Lab, Cystic Fibrosis Foundation, Lexington, MA 02421, USA
| | - Noah R Simon
- University of Washington, Seattle, WA 98195-9300, USA
| | | | - Karen S Raraigh
- Johns Hopkins University School of Medicine, Baltimore, MD 21205-2196, USA
| | - Garry R Cutting
- Johns Hopkins University School of Medicine, Baltimore, MD 21205-2196, USA
| | | | - Robert J Bridges
- Rosalind Franklin University Medical School, Chicago, IL 60064, USA
| | - Philip J Thomas
- University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Martin Mense
- CFFT Lab, Cystic Fibrosis Foundation, Lexington, MA 02421, USA.
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4
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Taniguchi S, Berenger F, Doi Y, Mimura A, Yamanishi Y, Okiyoneda T. Ligand-based virtual-screening identified a novel CFTR ligand which improves the defective cell surface expression of misfolded ABC transporters. Front Pharmacol 2024; 15:1370676. [PMID: 38666024 PMCID: PMC11043560 DOI: 10.3389/fphar.2024.1370676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Accepted: 04/01/2024] [Indexed: 04/28/2024] Open
Abstract
Cystic fibrosis (CF) is a monogenetic disease caused by the mutation of CFTR, a cAMP-regulated Cl- channel expressing at the apical plasma membrane (PM) of epithelia. ∆F508-CFTR, the most common mutant in CF, fails to reach the PM due to its misfolding and premature degradation at the endoplasmic reticulum (ER). Recently, CFTR modulators have been developed to correct CFTR abnormalities, with some being used as therapeutic agents for CF treatment. One notable example is Trikafta, a triple combination of CFTR modulators (TEZ/ELX/IVA), which significantly enhances the functionality of ΔF508-CFTR on the PM. However, there's room for improvement in its therapeutic effectiveness since TEZ/ELX/IVA doesn't fully stabilize ΔF508-CFTR on the PM. To discover new CFTR modulators, we conducted a virtual screening of approximately 4.3 million compounds based on the chemical structures of existing CFTR modulators. This effort led us to identify a novel CFTR ligand named FR3. Unlike clinically available CFTR modulators, FR3 appears to operate through a distinct mechanism of action. FR3 enhances the functional expression of ΔF508-CFTR on the apical PM in airway epithelial cell lines by stabilizing NBD1. Notably, FR3 counteracted the degradation of mature ΔF508-CFTR, which still occurs despite the presence of TEZ/ELX/IVA. Furthermore, FR3 corrected the defective PM expression of a misfolded ABCB1 mutant. Therefore, FR3 may be a potential lead compound for addressing diseases resulting from the misfolding of ABC transporters.
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Affiliation(s)
- Shogo Taniguchi
- Department of Biomedical Sciences, School of Biological and Environmental Sciences, Kwansei Gakuin University, Nishinomiya, Japan
| | - Francois Berenger
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Japan
| | - Yukako Doi
- Department of Biomedical Sciences, School of Biological and Environmental Sciences, Kwansei Gakuin University, Nishinomiya, Japan
| | - Ayana Mimura
- Department of Biomedical Sciences, School of Biological and Environmental Sciences, Kwansei Gakuin University, Nishinomiya, Japan
| | - Yoshihiro Yamanishi
- Department of Complex Systems Science, Graduate School of Informatics, Nagoya University, Graduate School of Informatics, Nagoya University, Nagoya, Japan
| | - Tsukasa Okiyoneda
- Department of Biomedical Sciences, School of Biological and Environmental Sciences, Kwansei Gakuin University, Nishinomiya, Japan
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5
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Coller J, Ignatova Z. tRNA therapeutics for genetic diseases. Nat Rev Drug Discov 2024; 23:108-125. [PMID: 38049504 DOI: 10.1038/s41573-023-00829-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/11/2023] [Indexed: 12/06/2023]
Abstract
Transfer RNAs (tRNAs) have a crucial role in protein synthesis, and in recent years, their therapeutic potential for the treatment of genetic diseases - primarily those associated with a mutation altering mRNA translation - has gained significant attention. Engineering tRNAs to readthrough nonsense mutation-associated premature termination of mRNA translation can restore protein synthesis and function. In addition, supplementation of natural tRNAs can counteract effects of missense mutations in proteins crucial for tRNA biogenesis and function in translation. This Review will present advances in the development of tRNA therapeutics with high activity and safety in vivo and discuss different formulation approaches for single or chronic treatment modalities. The field of tRNA therapeutics is still in its early stages, and a series of challenges related to tRNA efficacy and stability in vivo, delivery systems with tissue-specific tropism, and safe and efficient manufacturing need to be addressed.
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Affiliation(s)
- Jeff Coller
- Department of Molecular Biology and Genetics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA.
| | - Zoya Ignatova
- Institute of Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany.
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6
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de Souza Goncalves L, Chu T, Master R, Chhetri PD, Gao Q, Cil O. Mg2+ supplementation treats secretory diarrhea in mice by activating calcium-sensing receptor in intestinal epithelial cells. J Clin Invest 2024; 134:e171249. [PMID: 37962961 PMCID: PMC10786700 DOI: 10.1172/jci171249] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 11/09/2023] [Indexed: 11/16/2023] Open
Abstract
Cholera is a global health problem with no targeted therapies. The Ca2+-sensing receptor (CaSR) is a regulator of intestinal ion transport and a therapeutic target for diarrhea, and Ca2+ is considered its main agonist. We found that increasing extracellular Ca2+ had a minimal effect on forskolin-induced Cl- secretion in human intestinal epithelial T84 cells. However, extracellular Mg2+, an often-neglected CaSR agonist, suppressed forskolin-induced Cl- secretion in T84 cells by 65% at physiological levels seen in stool (10 mM). The effect of Mg2+ occurred via the CaSR/Gq signaling that led to cAMP hydrolysis. Mg2+ (10 mM) also suppressed Cl- secretion induced by cholera toxin, heat-stable E. coli enterotoxin, and vasoactive intestinal peptide by 50%. In mouse intestinal closed loops, luminal Mg2+ treatment (20 mM) inhibited cholera toxin-induced fluid accumulation by 40%. In a mouse intestinal perfusion model of cholera, addition of 10 mM Mg2+ to the perfusate reversed net fluid transport from secretion to absorption. These results suggest that Mg2+ is the key CaSR activator in mouse and human intestinal epithelia at physiological levels in stool. Since stool Mg2+ concentrations in patients with cholera are essentially zero, oral Mg2+ supplementation, alone or in an oral rehydration solution, could be a potential therapy for cholera and other cyclic nucleotide-mediated secretory diarrheas.
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7
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Csanády L. Towards personalized medicine for cystic fibrosis patients with rare mutations. J Physiol 2024; 602:257-258. [PMID: 38167788 DOI: 10.1113/jp286135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 12/20/2023] [Indexed: 01/05/2024] Open
Affiliation(s)
- László Csanády
- Department of Biochemistry, Semmelweis University, Budapest, Hungary
- Hungarian Centre of Excellence for Molecular Medicine - Semmelweis University Molecular Channelopathies Research Group, Budapest, Hungary
- Hungarian Research Network - Semmelweis University Ion Channel Research Group, Budapest, Hungary
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8
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Li H, Rodrat M, Al-Salmani MK, Veselu DF, Han ST, Raraigh KS, Cutting GR, Sheppard DN. Two rare variants that affect the same amino acid in CFTR have distinct responses to ivacaftor. J Physiol 2024; 602:333-354. [PMID: 38186087 PMCID: PMC10872379 DOI: 10.1113/jp285727] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 12/11/2023] [Indexed: 01/09/2024] Open
Abstract
Some residues in the cystic fibrosis transmembrane conductance regulator (CFTR) channel are the site of more than one CFTR variant that cause cystic fibrosis. Here, we investigated the function of S1159F and S1159P, two variants associated with different clinical phenotypes, which affect the same pore-lining residue in transmembrane segment 12 that are both strongly potentiated by ivacaftor when expressed in CFBE41o- bronchial epithelial cells. To study the single-channel behaviour of CFTR, we applied the patch-clamp technique to Chinese hamster ovary cells heterologously expressing CFTR variants incubated at 27°C to enhance channel residence at the plasma membrane. S1159F- and S1159P-CFTR formed Cl- channels activated by cAMP-dependent phosphorylation and gated by ATP that exhibited thermostability at 37°C. Both variants modestly reduced the single-channel conductance of CFTR. By severely attenuating channel gating, S1159F- and S1159P-CFTR reduced the open probability (Po ) of wild-type CFTR by ≥75% at ATP (1 mM); S1159F-CFTR caused the greater decrease in Po consistent with its more severe clinical phenotype. Ivacaftor (10-100 nM) doubled the Po of both CFTR variants without restoring Po values to wild-type levels, but concomitantly, ivacaftor decreased current flow through open channels. For S1159F-CFTR, the reduction of current flow was marked at high (supersaturated) ivacaftor concentrations (0.5-1 μM) and voltage-independent, identifying an additional detrimental action of elevated ivacaftor concentrations. In conclusion, S1159F and S1159P are gating variants, which also affect CFTR processing and conduction, but not stability, necessitating the use of combinations of CFTR modulators to optimally restore their channel activity. KEY POINTS: Dysfunction of the ion channel cystic fibrosis transmembrane conductance regulator (CFTR) causes the genetic disease cystic fibrosis (CF). This study investigated two rare pathogenic CFTR variants, S1159F and S1159P, which affect the same amino acid in CFTR, to understand the molecular basis of disease and response to the CFTR-targeted therapy ivacaftor. Both rare variants diminished CFTR function by modestly reducing current flow through the channel and severely inhibiting ATP-dependent channel gating with S1159F exerting the stronger adverse effect, which correlates with its association with more severe disease. Ivacaftor potentiated channel gating by both rare variants without restoring their activity to wild-type levels, but concurrently reduced current flow through open channels, particularly those of S1159F-CFTR. Our data demonstrate that S1159F and S1159P cause CFTR dysfunction by multiple mechanisms that require combinations of CFTR-targeted therapies to fully restore channel function.
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Affiliation(s)
- Hongyu Li
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Mayuree Rodrat
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
- Center of Research and Development for Biomedical Instrumentation, Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, Thailand
| | - Majid K Al-Salmani
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
- Department of Physiology, College of Medicine and Health Sciences, Sultan Qaboos University, Al Khoudh, Muscat, Sultanate of Oman
| | | | - Sangwoo T Han
- Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Karen S Raraigh
- Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Garry R Cutting
- Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - David N Sheppard
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
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9
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Yeh HI, Sutcliffe KJ, Sheppard DN, Hwang TC. CFTR Modulators: From Mechanism to Targeted Therapeutics. Handb Exp Pharmacol 2024; 283:219-247. [PMID: 35972584 DOI: 10.1007/164_2022_597] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
People with cystic fibrosis (CF) suffer from a multi-organ disorder caused by loss-of-function variants in the gene encoding the epithelial anion channel cystic fibrosis transmembrane conductance regulator (CFTR). Tremendous progress has been made in both basic and clinical sciences over the past three decades since the identification of the CFTR gene. Over 90% of people with CF now have access to therapies targeting dysfunctional CFTR. This success was made possible by numerous studies in the field that incrementally paved the way for the development of small molecules known as CFTR modulators. The advent of CFTR modulators transformed this life-threatening illness into a treatable disease by directly binding to the CFTR protein and correcting defects induced by pathogenic variants. In this chapter, we trace the trajectory of structural and functional studies that brought CF therapies from bench to bedside, with an emphasis on mechanistic understanding of CFTR modulators.
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Affiliation(s)
- Han-I Yeh
- Department of Pharmacology, National Yang Ming Chiao Tung University, Taipei City, Taiwan
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, USA
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, USA
| | - Katy J Sutcliffe
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - David N Sheppard
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Tzyh-Chang Hwang
- Department of Pharmacology, National Yang Ming Chiao Tung University, Taipei City, Taiwan.
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, USA.
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, USA.
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10
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Kleinfelder K, Lotti V, Eramo A, Amato F, Lo Cicero S, Castelli G, Spadaro F, Farinazzo A, Dell’Orco D, Preato S, Conti J, Rodella L, Tomba F, Cerofolini A, Baldisseri E, Bertini M, Volpi S, Villella VR, Esposito S, Zollo I, Castaldo G, Laudanna C, Sorsher EJ, Hong J, Joshi D, Cutting G, Lucarelli M, Melotti P, Sorio C. In silico analysis and theratyping of an ultra-rare CFTR genotype (W57G/A234D) in primary human rectal and nasal epithelial cells. iScience 2023; 26:108180. [PMID: 38026150 PMCID: PMC10660498 DOI: 10.1016/j.isci.2023.108180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 04/22/2023] [Accepted: 10/09/2023] [Indexed: 12/01/2023] Open
Abstract
Mutation targeted therapy in cystic fibrosis (CF) is still not eligible for all CF subjects, especially for cases carrying rare variants such as the CFTR genotype W57G/A234D (c.169T>G/c.701C>A). We performed in silico analysis of the effects of these variants on protein stability, which we functionally characterized using colonoids and reprogrammed nasal epithelial cells. The effect of mutations on cystic fibrosis transmembrane conductance regulator (CFTR) protein was analyzed by western blotting, forskolin-induced swelling (FIS), and Ussing chamber analysis. We detected a residual CFTR function that increases following treatment with the CFTR modulators VX661±VX445±VX770, correlates among models, and is associated with increased CFTR protein levels following treatment with CFTR correctors. In vivo treatment with VX770 reduced sweat chloride concentration to non-CF levels, increased the number of CFTR-dependent sweat droplets, and induced a 6% absolute increase in predicted FEV1% after 27 weeks of treatment indicating the relevance of theratyping with patient-derived cells in CF.
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Affiliation(s)
- Karina Kleinfelder
- Department of Medicine, University of Verona, Division of General Pathology, 37134 Verona, Italy
| | - Virginia Lotti
- Department of Medicine, University of Verona, Division of General Pathology, 37134 Verona, Italy
| | - Adriana Eramo
- Department of Oncology and Molecular Medicine, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Felice Amato
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131 Naples, Italy
- CEINGE-Biotecnologie Avanzate Franco Salvatore S.c.a.r.l., 80145 Naples, Italy
| | - Stefania Lo Cicero
- Department of Oncology and Molecular Medicine, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Germana Castelli
- Department of Oncology and Molecular Medicine, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Francesca Spadaro
- Confocal Microscopy Unit, Core Facilities, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Alessia Farinazzo
- Department of Medicine, University of Verona, Division of General Pathology, 37134 Verona, Italy
| | - Daniele Dell’Orco
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134 Verona, Italy
| | - Sara Preato
- Department of Medicine, University of Verona, Division of General Pathology, 37134 Verona, Italy
| | - Jessica Conti
- Department of Medicine, University of Verona, Division of General Pathology, 37134 Verona, Italy
| | - Luca Rodella
- Endoscopic Surgery Unit, Azienda Ospedaliera Universitaria Integrata Verona, 37126 Verona, Italy
| | - Francesco Tomba
- Endoscopic Surgery Unit, Azienda Ospedaliera Universitaria Integrata Verona, 37126 Verona, Italy
| | - Angelo Cerofolini
- Endoscopic Surgery Unit, Azienda Ospedaliera Universitaria Integrata Verona, 37126 Verona, Italy
| | - Elena Baldisseri
- Cystic Fibrosis Centre, Azienda Ospedaliera Universitaria Integrata Verona, 37126 Verona, Italy
| | - Marina Bertini
- Cystic Fibrosis Centre, Azienda Ospedaliera Universitaria Integrata Verona, 37126 Verona, Italy
| | - Sonia Volpi
- Cystic Fibrosis Centre, Azienda Ospedaliera Universitaria Integrata Verona, 37126 Verona, Italy
| | - Valeria Rachela Villella
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131 Naples, Italy
- CEINGE-Biotecnologie Avanzate Franco Salvatore S.c.a.r.l., 80145 Naples, Italy
| | - Speranza Esposito
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131 Naples, Italy
- CEINGE-Biotecnologie Avanzate Franco Salvatore S.c.a.r.l., 80145 Naples, Italy
| | - Immacolata Zollo
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131 Naples, Italy
- CEINGE-Biotecnologie Avanzate Franco Salvatore S.c.a.r.l., 80145 Naples, Italy
| | - Giuseppe Castaldo
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131 Naples, Italy
- CEINGE-Biotecnologie Avanzate Franco Salvatore S.c.a.r.l., 80145 Naples, Italy
| | - Carlo Laudanna
- Department of Medicine, University of Verona, Division of General Pathology, 37134 Verona, Italy
| | - Eric J. Sorsher
- Department of Pediatrics, Division of Pulmonary, Allergy/Immunology, Cystic Fibrosis & Sleep, Emory University, Atlanta, GA 30322, USA
| | - Jeong Hong
- Department of Pediatrics, Division of Pulmonary, Allergy/Immunology, Cystic Fibrosis & Sleep, Emory University, Atlanta, GA 30322, USA
| | - Disha Joshi
- Department of Pediatrics, Division of Pulmonary, Allergy/Immunology, Cystic Fibrosis & Sleep, Emory University, Atlanta, GA 30322, USA
| | - Garry Cutting
- McKusick-Nathans Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Marco Lucarelli
- Department of Experimental Medicine, Sapienza University of Rome, 00185 Rome, Italy
- Pasteur Institute, Cenci Bolognetti Foundation, Sapienza University of Rome, 00161 Rome, Italy
| | - Paola Melotti
- Cystic Fibrosis Centre, Azienda Ospedaliera Universitaria Integrata Verona, 37126 Verona, Italy
| | - Claudio Sorio
- Department of Medicine, University of Verona, Division of General Pathology, 37134 Verona, Italy
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11
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Rab A, Yang X, Tracy WF, Hong JS, Joshi D, Manfredi C, Ponnaluri SS, Kolykhalov AA, Qui M, Fu H, Du Y, Davies HML, Sorscher EJ. A Novel 7 H-[1,2,4]Triazolo[3,4- b]thiadiazine-based Cystic Fibrosis Transmembrane Conductance Regulator Potentiator Directed toward Treatment of Cystic Fibrosis. ACS Med Chem Lett 2023; 14:1338-1343. [PMID: 37849531 PMCID: PMC10577695 DOI: 10.1021/acsmedchemlett.3c00155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Accepted: 08/25/2023] [Indexed: 10/19/2023] Open
Abstract
Cystic fibrosis (CF) is an autosomal genetic disorder caused by disrupted anion transport in epithelial cells lining tissues in the human airways and digestive system. While cystic fibrosis transmembrane conductance regulator (CFTR) modulator compounds have provided transformative improvement in CF respiratory function, certain patients exhibit marginal clinical benefit or detrimental effects or have a form of the disease not approved or unlikely to respond using CFTR modulation. We tested hit compounds from a 300,000-drug screen for their ability to augment CFTR transepithelial transport alone or in combination with the FDA-approved CFTR potentiator ivacaftor (VX-770). A subsequent SAR campaign led us to a class of 7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazines that in combination with VX-770 rescued function of G551D mutant CFTR channels to approximately 400% above the activity of VX-770 alone and to nearly wild-type CFTR levels in the same Fischer rat thyroid model system.
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Affiliation(s)
- Andras Rab
- Department
of Pediatrics, Emory University School of
Medicine, Atlanta, Georgia 30322, United States
| | - Xun Yang
- Department
of Chemistry, Emory University, 1515 Dickey Dr., Atlanta, Georgia 30329, United States
| | - William F. Tracy
- Department
of Chemistry, Emory University, 1515 Dickey Dr., Atlanta, Georgia 30329, United States
| | - Jeong S. Hong
- Department
of Pediatrics, Emory University School of
Medicine, Atlanta, Georgia 30322, United States
| | - Disha Joshi
- Department
of Pediatrics, Emory University School of
Medicine, Atlanta, Georgia 30322, United States
| | - Candela Manfredi
- Department
of Pediatrics, Emory University School of
Medicine, Atlanta, Georgia 30322, United States
| | - Sadhana S. Ponnaluri
- Department
of Pediatrics, Emory University School of
Medicine, Atlanta, Georgia 30322, United States
| | | | - Min Qui
- Department
of Pharmacology and Chemical Biology, Emory
University School of Medicine, Atlanta, Georgia 30322, United States
- Emory
Chemical Biology Discovery Center, Emory
University School of Medicine, Atlanta, Georgia 30322, United States
| | - Haian Fu
- Department
of Pharmacology and Chemical Biology, Emory
University School of Medicine, Atlanta, Georgia 30322, United States
- Emory
Chemical Biology Discovery Center, Emory
University School of Medicine, Atlanta, Georgia 30322, United States
| | - Yuhong Du
- Department
of Pharmacology and Chemical Biology, Emory
University School of Medicine, Atlanta, Georgia 30322, United States
- Emory
Chemical Biology Discovery Center, Emory
University School of Medicine, Atlanta, Georgia 30322, United States
| | - Huw M. L. Davies
- Department
of Chemistry, Emory University, 1515 Dickey Dr., Atlanta, Georgia 30329, United States
| | - Eric J. Sorscher
- Department
of Pediatrics, Emory University School of
Medicine, Atlanta, Georgia 30322, United States
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12
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Kim M, McDonald EF, Sabusap CMP, Timalsina B, Joshi D, Hong JS, Rab A, Sorscher EJ, Plate L. Elexacaftor/VX-445-mediated CFTR interactome remodeling reveals differential correction driven by mutation-specific translational dynamics. J Biol Chem 2023; 299:105242. [PMID: 37690692 PMCID: PMC10579539 DOI: 10.1016/j.jbc.2023.105242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 08/30/2023] [Accepted: 09/04/2023] [Indexed: 09/12/2023] Open
Abstract
Cystic fibrosis (CF) is one of the most prevalent lethal genetic diseases with over 2000 identified mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Pharmacological chaperones such as lumacaftor (VX-809), tezacaftor (VX-661), and elexacaftor (VX-445) treat mutation-induced defects by stabilizing CFTR and are called correctors. These correctors improve proper folding and thus facilitate processing and trafficking to increase the amount of functional CFTR on the cell surface. Yet, CFTR variants display differential responses to each corrector. Here, we report that variants P67L and L206W respond similarly to VX-809 but divergently to VX-445 with P67L exhibiting little rescue when treated with VX-445. We investigate the underlying cellular mechanisms of how CFTR biogenesis is altered by correctors in these variants. Affinity purification-mass spectrometry multiplexed with isobaric tandem mass tags was used to quantify CFTR protein-protein interaction changes between variants P67L and L206W. VX-445 facilitates unique proteostasis factor interactions especially in translation, folding, and degradation pathways in a CFTR variant-dependent manner. A number of these interacting proteins knocked down by siRNA, such as ribosomal subunit proteins, moderately rescued fully glycosylated P67L. Importantly, these knockdowns sensitize P67L to VX-445 and further enhance the trafficking correction of this variant. Partial inhibition of protein translation also mildly sensitizes P67L CFTR to VX-445 correction, supporting a role for translational dynamics in the rescue mechanism of VX-445. Our results provide a better understanding of VX-445 biological mechanism of action and reveal cellular targets that may sensitize nonresponsive CFTR variants to known and available correctors.
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Affiliation(s)
- Minsoo Kim
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA; Program in Chemical and Physical Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - Eli Fritz McDonald
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA
| | | | - Bibek Timalsina
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA
| | - Disha Joshi
- Department of Pediatrics, Emory University, Atlanta, Georgia, USA
| | - Jeong S Hong
- Department of Pediatrics, Emory University, Atlanta, Georgia, USA
| | - Andras Rab
- Department of Pediatrics, Emory University, Atlanta, Georgia, USA
| | - Eric J Sorscher
- Department of Pediatrics, Emory University, Atlanta, Georgia, USA
| | - Lars Plate
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA; Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA; Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
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13
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McKee AG, McDonald EF, Penn WD, Kuntz CP, Noguera K, Chamness LM, Roushar FJ, Meiler J, Oliver KE, Plate L, Schlebach JP. General trends in the effects of VX-661 and VX-445 on the plasma membrane expression of clinical CFTR variants. Cell Chem Biol 2023; 30:632-642.e5. [PMID: 37253358 PMCID: PMC10330547 DOI: 10.1016/j.chembiol.2023.05.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 02/17/2023] [Accepted: 05/05/2023] [Indexed: 06/01/2023]
Abstract
Cystic fibrosis (CF) is caused by mutations that compromise the expression and/or function of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel. Most people with CF harbor a common misfolded variant (ΔF508) that can be partially rescued by therapeutic "correctors" that restore its expression. Nevertheless, many other CF variants are insensitive to correctors. Using deep mutational scanning, we quantitatively compare the effects of two correctors on the plasma membrane expression of 129 CF variants. Though structural calculations suggest corrector binding provides similar stabilization to most variants, it's those with intermediate expression and mutations near corrector binding pockets that exhibit the greatest response. Deviations in sensitivity appear to depend on the degree of variant destabilization and the timing of misassembly. Combining correctors appears to rescue more variants by doubling the binding energy and stabilizing distinct cotranslational folding transitions. These results provide an overview of rare CF variant expression and establish new tools for precision pharmacology.
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Affiliation(s)
- Andrew G McKee
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Eli F McDonald
- Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Wesley D Penn
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Charles P Kuntz
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Karen Noguera
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Laura M Chamness
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Francis J Roushar
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Jens Meiler
- Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA; Institute for Drug Development, Leipzig University, Leipzig, SAC 04109, Germany
| | - Kathryn E Oliver
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Lars Plate
- Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA; Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA
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14
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Albers S, Allen EC, Bharti N, Davyt M, Joshi D, Perez-Garcia CG, Santos L, Mukthavaram R, Delgado-Toscano MA, Molina B, Kuakini K, Alayyoubi M, Park KJJ, Acharya G, Gonzalez JA, Sagi A, Birket SE, Tearney GJ, Rowe SM, Manfredi C, Hong JS, Tachikawa K, Karmali P, Matsuda D, Sorscher EJ, Chivukula P, Ignatova Z. Engineered tRNAs suppress nonsense mutations in cells and in vivo. Nature 2023; 618:842-848. [PMID: 37258671 PMCID: PMC10284701 DOI: 10.1038/s41586-023-06133-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 04/25/2023] [Indexed: 06/02/2023]
Abstract
Nonsense mutations are the underlying cause of approximately 11% of all inherited genetic diseases1. Nonsense mutations convert a sense codon that is decoded by tRNA into a premature termination codon (PTC), resulting in an abrupt termination of translation. One strategy to suppress nonsense mutations is to use natural tRNAs with altered anticodons to base-pair to the newly emerged PTC and promote translation2-7. However, tRNA-based gene therapy has not yielded an optimal combination of clinical efficacy and safety and there is presently no treatment for individuals with nonsense mutations. Here we introduce a strategy based on altering native tRNAs into efficient suppressor tRNAs (sup-tRNAs) by individually fine-tuning their sequence to the physico-chemical properties of the amino acid that they carry. Intravenous and intratracheal lipid nanoparticle (LNP) administration of sup-tRNA in mice restored the production of functional proteins with nonsense mutations. LNP-sup-tRNA formulations caused no discernible readthrough at endogenous native stop codons, as determined by ribosome profiling. At clinically important PTCs in the cystic fibrosis transmembrane conductance regulator gene (CFTR), the sup-tRNAs re-established expression and function in cell systems and patient-derived nasal epithelia and restored airway volume homeostasis. These results provide a framework for the development of tRNA-based therapies with a high molecular safety profile and high efficacy in targeted PTC suppression.
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Affiliation(s)
- Suki Albers
- Institute of Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany
| | | | - Nikhil Bharti
- Institute of Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany
| | - Marcos Davyt
- Institute of Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany
| | - Disha Joshi
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, USA
- Children's Healthcare of Atlanta, Atlanta, GA, USA
| | | | - Leonardo Santos
- Institute of Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany
| | | | | | | | | | | | | | | | | | - Amit Sagi
- Arcturus Therapeutics, San Diego, CA, USA
| | - Susan E Birket
- Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Guillermo J Tearney
- Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, USA
- Harvard-MIT Health Sciences and Technology, MA, Cambridge, USA
| | - Steven M Rowe
- Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Candela Manfredi
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, USA
- Children's Healthcare of Atlanta, Atlanta, GA, USA
| | - Jeong S Hong
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, USA
- Children's Healthcare of Atlanta, Atlanta, GA, USA
| | | | | | | | - Eric J Sorscher
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, USA.
- Children's Healthcare of Atlanta, Atlanta, GA, USA.
| | | | - Zoya Ignatova
- Institute of Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany.
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15
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Railean V, Rodrigues CS, Ramalho SS, Silva IAL, Bartosch J, Farinha CM, Pankonien I, Amaral MD. Personalized medicine: Function of CFTR variant p.Arg334Trp is rescued by currently available CFTR modulators. Front Mol Biosci 2023; 10:1155705. [PMID: 37006619 PMCID: PMC10063961 DOI: 10.3389/fmolb.2023.1155705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 03/06/2023] [Indexed: 03/19/2023] Open
Abstract
Most of the 2,100 CFTR gene variants reported to date are still unknown in terms of their disease liability in Cystic Fibrosis (CF) and their molecular and cellular mechanism that leads to CFTR dysfunction. Since some rare variants may respond to currently approved modulators, characterizing their defect and response to these drugs is essential for effective treatment of people with CF (pwCF) not eligible for the current treatment. Here, we assessed how the rare variant, p.Arg334Trp, impacts on CFTR traffic and function and its response to existing CFTR modulators. To this end, we performed the forskolin-induced swelling (FIS) assay on intestinal organoids from 10 pwCF bearing the p.Arg334Trp variant in one or both alleles of the CFTR gene. In parallel, a novel p.Arg334Trp-CFTR expressing CFBE cell line was generated to characterize the variant individually. Results show that p.Arg334Trp-CFTR does not significantly affect the plasma membrane traffic of CFTR and evidences residual CFTR function. This CFTR variant is rescued by currently available CFTR modulators independently of the variant in the second allele. The study, predicting clinical benefit for CFTR modulators in pwCF with at least one p.Arg334Trp variant, demonstrates the high potential of personalized medicine through theranostics to extend the label of approved drugs for pwCF carrying rare CFTR variants. We recommend that this personalized approach should be considered for drug reimbursement policies by health insurance systems/national health services.
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16
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Zacarias S, Batista MSP, Ramalho SS, Victor BL, Farinha CM. Rescue of Rare CFTR Trafficking Mutants Highlights a Structural Location-Dependent Pattern for Correction. Int J Mol Sci 2023; 24:ijms24043211. [PMID: 36834620 PMCID: PMC9961391 DOI: 10.3390/ijms24043211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 01/30/2023] [Accepted: 01/31/2023] [Indexed: 02/08/2023] Open
Abstract
Cystic Fibrosis (CF) is a genetic disease caused by mutations in the gene encoding the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) channel. Currently, more than 2100 variants have been identified in the gene, with a large number being very rare. The approval of modulators that act on mutant CFTR protein, correcting its molecular defect and thus alleviating the burden of the disease, revolutionized the field of CF. However, these drugs do not apply to all patients with CF, especially those with rare mutations-for which there is a lack of knowledge on the molecular mechanisms of the disease and the response to modulators. In this work, we evaluated the impact of several rare putative class II mutations on the expression, processing, and response of CFTR to modulators. Novel cell models consisting of bronchial epithelial cell lines expressing CFTR with 14 rare variants were created. The variants studied are localized at Transmembrane Domain 1 (TMD1) or very close to the signature motif of Nucleotide Binding Domain 1 (NBD1). Our data show that all mutations analyzed significantly decrease CFTR processing and while TMD1 mutations respond to modulators, those localized in NBD1 do not. Molecular modeling calculations confirm that the mutations in NBD1 induce greater destabilization of CFTR structure than those in TMD1. Furthermore, the structural proximity of TMD1 mutants to the reported binding site of CFTR modulators such as VX-809 and VX-661, make them more efficient in stabilizing the CFTR mutants analyzed. Overall, our data suggest a pattern for mutation location and impact in response to modulators that correlates with the global effect of the mutations on CFTR structure.
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17
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Kim M, McDonald EF, Sabusap CMP, Timalsina B, Joshi D, Hong JS, Rab A, Sorscher EJ, Plate L. Elexacaftor/VX-445-mediated CFTR interactome remodeling reveals differential correction driven by mutation-specific translational dynamics. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.04.527134. [PMID: 36778339 PMCID: PMC9915750 DOI: 10.1101/2023.02.04.527134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Cystic fibrosis (CF) is one of the most prevalent lethal genetic diseases with over 2000 identified mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Pharmacological chaperones such as Lumacaftor (VX-809), Tezacaftor (VX-661) and Elexacaftor (VX-445) treat mutation-induced defects by stabilizing CFTR and are called correctors. These correctors improve proper folding and thus facilitate processing and trafficking to increase the amount of functional CFTR on the cell surface. Yet, CFTR variants display differential responses to each corrector. Here, we report variants P67L and L206W respond similarly to VX-809 but divergently to VX-445 with P67L exhibiting little rescue when treated with VX-445. We investigate the underlying cellular mechanisms of how CFTR biogenesis is altered by correctors in these variants. Affinity purification-mass spectrometry (AP-MS) multiplexed with isobaric Tandem Mass Tags (TMT) was used to quantify CFTR protein-protein interaction changes between variants P67L and L206W. VX-445 facilitates unique proteostasis factor interactions especially in translation, folding, and degradation pathways in a CFTR variant-dependent manner. A number of these interacting proteins knocked down by siRNA, such as ribosomal subunit proteins, moderately rescued fully glycosylated P67L. Importantly, these knock-downs sensitize P67L to VX-445 and further enhance the correction of this variant. Our results provide a better understanding of VX-445 biological mechanism of action and reveal cellular targets that may sensitize unresponsive CFTR variants to known and available correctors.
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Affiliation(s)
- Minsoo Kim
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States of America
- Program in Chemical and Physical Biology, Vanderbilt University, Nashville, TN, United States of America
| | - Eli Fritz McDonald
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States of America
| | | | - Bibek Timalsina
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States of America
| | - Disha Joshi
- Department of Pediatrics, Emory University, Atlanta, GA, United States of America
| | - Jeong S. Hong
- Department of Pediatrics, Emory University, Atlanta, GA, United States of America
| | - Andras Rab
- Department of Pediatrics, Emory University, Atlanta, GA, United States of America
| | - Eric J. Sorscher
- Department of Pediatrics, Emory University, Atlanta, GA, United States of America
| | - Lars Plate
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States of America
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, United States of America
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, United States of America
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18
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Stanke F, Pallenberg ST, Tamm S, Hedtfeld S, Eichhorn EM, Minso R, Hansen G, Welte T, Sauer-Heilborn A, Ringshausen FC, Junge S, Tümmler B, Dittrich AM. Changes in cystic fibrosis transmembrane conductance regulator protein expression prior to and during elexacaftor-tezacaftor-ivacaftor therapy. Front Pharmacol 2023; 14:1114584. [PMID: 36778025 PMCID: PMC9911415 DOI: 10.3389/fphar.2023.1114584] [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: 12/02/2022] [Accepted: 01/16/2023] [Indexed: 01/28/2023] Open
Abstract
Background: Defects in expression, maturation or function of the epithelial membrane glycoprotein CFTR are causative for the progressive disease cystic fibrosis. Recently, molecular therapeutics that improve CFTR maturation and functional defects have been approved. We aimed to verify whether we could detect an improvement of CFTR protein expression and maturation by triple therapy with elexacaftor-tezacaftor-ivacaftor (ELX/TEZ/IVA). Methods: Rectal suction biopsies of 21 p.Phe508del homozygous or compound heterozygous CF patients obtained pre- and during treatment with ELX/TEZ/IVA were analyzed by CFTR Western blot that was optimized to distinguish CFTR glycoisoforms. Findings: CFTR western immunoblot analysis revealed that-compared to baseline-the levels of CFTR protein increased by at least twofold in eight out of 12 patients upon treatment with ELX/TEZ/IVA compared to baseline (p < 0.02). However, polydispersity of the mutant CFTR protein was lower than that of the fully glycosylated wild type CFTR Golgi isoform, indicating an incompletely glycosylated p.Phe508el CFTR protein isoform C* in patients with CF which persists after ELX/TEZ/IVA treatment. Interpretation: Treatment with ELX/TEZ/IVA increased protein expression by facilitating the posttranslational processing of mutant CFTR but apparently did not succeed in generating the polydisperse spectrum of N-linked oligosaccharides that is characteristic for the wild type CFTR band C glycoisoform. Our results caution that the lower amounts or immature glycosylation of the C* glycoisoform observed in patients' biomaterial might not translate to fully restored function of mutant CFTR necessary for long-term provision of clinical benefit.
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Affiliation(s)
- Frauke Stanke
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, Hannover, Germany,*Correspondence: Frauke Stanke,
| | - Sophia T. Pallenberg
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany
| | - Stephanie Tamm
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, Hannover, Germany
| | - Silke Hedtfeld
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany
| | - Ella M. Eichhorn
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany
| | - Rebecca Minso
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany
| | - Gesine Hansen
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, Hannover, Germany
| | - Tobias Welte
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, Hannover, Germany,Department of Respiratory Medicine, Hannover Medical School, Hannover, Germany
| | | | - Felix C. Ringshausen
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, Hannover, Germany,Department of Respiratory Medicine, Hannover Medical School, Hannover, Germany
| | - Sibylle Junge
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany
| | - Burkhard Tümmler
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, Hannover, Germany
| | - Anna-Maria Dittrich
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, Hannover, Germany
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19
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Mayer-Hamblett N, Zemanick ET, Odem-Davis K, VanDevanter D, Warden M, Rowe SM, Young J, Konstan MW, For-The-Chec-Sc-Study-Group. Characterizing CFTR modulated sweat chloride response across the cf population: Initial results from the CHEC-SC study. J Cyst Fibros 2023; 22:79-88. [PMID: 35871974 PMCID: PMC10103635 DOI: 10.1016/j.jcf.2022.07.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 06/24/2022] [Accepted: 07/12/2022] [Indexed: 10/17/2022]
Abstract
BACKGROUND CHEC-SC is an ongoing epidemiologic study characterizing modulator-induced sweat chloride (SC) responses across the CF population, with interim results available prior to the availability of triple combination modulator therapy. METHODS Eligible participants had been prescribed a modulator for ≥90 days with re-enrollment allowed upon establishment of a new modulator. Pre-modulator SC values were obtained from chart review; post-modulator sweat was collected and analyzed locally. SC changes were descriptively summarized with biologic sex effects adjusted for age, weight, and CFTR genotype. Heterogeneity in ivacaftor SC response was characterized in relation to published CFTR functional responses. RESULTS 1848 participants provided 2004 SC measurements, 26.2% on ivacaftor, 39.1% on lumacaftor/ivacaftor, and 34.7% on tezacaftor/ivacaftor. Average SC changes for all modulators were consistent with those reported in previous clinical studies, with greater variation in SC response observed among rarer mutations and notable shifts in the proportion with SC <60mmol/L independent of the magnitude of SC change. Ivacaftor induced in vitro CFTR functional change was significantly correlated with ivacaftor-modulated SC response (Pearson correlation= ‒0.52, 95% CI: ‒0.773, ‒0.129). Average SC change from ivacaftor to tezacaftor/ivacaftor was ‒4.9 mmol/L (n=17,95% CI:‒9.3, ‒0.5) and differed from those switching from lumacaftor/ivacaftor (10.0 mmol/L, n=139, 95% CI:7.8,12.3). Sex at birth was not associated with SC response. CONCLUSIONS CHEC-SC is the largest study characterizing modulator-induced SC changes across the CF population. There was a strong association between ivacaftor induced in vitro CFTR function and SC response across a genotypically heterogenous cohort. Biological sex was not associated with SC response.
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Affiliation(s)
- N Mayer-Hamblett
- University of Washington, Seattle, WA, United States; Seattle Children's Hospital, Seattle, WA, United States.
| | - E T Zemanick
- University of Colorado Anschutz Medical Campus, Aurora, CO, United States of America
| | - K Odem-Davis
- Seattle Children's Hospital, Seattle, WA, United States
| | - D VanDevanter
- Case Western Reserve University School of Medicine, Cleveland, OH, United States
| | - M Warden
- Seattle Children's Hospital, Seattle, WA, United States
| | - S M Rowe
- University of Alabama at Birmingham, Birmingham, AL, England
| | - J Young
- Seattle Children's Hospital, Seattle, WA, United States
| | - M W Konstan
- Case Western Reserve University School of Medicine, Cleveland, OH, United States; Rainbow Babies and Children's Hospital, Cleveland, OH, United States
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20
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Hillenaar T, Beekman J, van der Sluijs P, Braakman I. Redefining Hypo- and Hyper-Responding Phenotypes of CFTR Mutants for Understanding and Therapy. Int J Mol Sci 2022; 23:15170. [PMID: 36499495 PMCID: PMC9735543 DOI: 10.3390/ijms232315170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 11/11/2022] [Accepted: 11/23/2022] [Indexed: 12/03/2022] Open
Abstract
Mutations in CFTR cause misfolding and decreased or absent ion-channel function, resulting in the disease Cystic Fibrosis. Fortunately, a triple-modulator combination therapy (Trikafta) has been FDA-approved for 178 mutations, including all patients who have F508del on one allele. That so many CFTR mutants respond well to modulators developed for a single mutation is due to the nature of the folding process of this multidomain protein. We have addressed the question 'What characterizes the exceptions: the mutants that functionally respond either not or extremely well'. A functional response is the product of the number of CFTR molecules on the cell surface, open probability, and conductivity of the CFTR chloride channel. By combining biosynthetic radiolabeling with protease-susceptibility assays, we have followed CF-causing mutants during the early and late stages of folding in the presence and absence of modulators. Most CFTR mutants showed typical biochemical responses for each modulator, such as a TMD1 conformational change or an increase in (cell-surface) stability, regardless of a functional response. These modulators thus should still be considered for hypo-responder genotypes. Understanding both biochemical and functional phenotypes of outlier mutations will boost our insights into CFTR folding and misfolding, and lead to improved therapeutic strategies.
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Affiliation(s)
- Tamara Hillenaar
- Cellular Protein Chemistry, Bijvoet Centre for Biomolecular Research, Science for Life, Faculty of Science, Utrecht University, 3584 CS Utrecht, The Netherlands; (T.H.); (P.v.d.S.)
| | - Jeffrey Beekman
- Department of Pediatric Pulmonology, Wilhelmina Children’s Hospital, University Medical Center Utrecht, Utrecht University, Member of ERN-LUNG, 3584 EA Utrecht, The Netherlands;
- Regenerative Medicine Center Utrecht, University Medical Center Utrecht, Utrecht University, 3584 CT Utrecht, The Netherlands
- Centre for Living Technologies, Alliance TU/e, WUR, UU, UMC Utrecht, 3584 CB Utrecht, The Netherlands
| | - Peter van der Sluijs
- Cellular Protein Chemistry, Bijvoet Centre for Biomolecular Research, Science for Life, Faculty of Science, Utrecht University, 3584 CS Utrecht, The Netherlands; (T.H.); (P.v.d.S.)
| | - Ineke Braakman
- Cellular Protein Chemistry, Bijvoet Centre for Biomolecular Research, Science for Life, Faculty of Science, Utrecht University, 3584 CS Utrecht, The Netherlands; (T.H.); (P.v.d.S.)
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21
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Abstract
Cystic fibrosis (CF) is a multiorgan disease caused by a wide variety of mutations in the cystic fibrosis transmembrane conductance regulator gene. As treatment has progressed from symptom mitigation to targeting of specific molecular defects, genetics has played an important role in identifying the proper precision therapies for each individual. Novel therapeutic approaches are focused on expanding treatment to a greater number of individuals as well as working toward a cure. This review discusses the role of genetics in our understanding of CF with a particular emphasis on how genetics informs the exciting landscape of current and novel CF therapies.
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Affiliation(s)
- Anya T Joynt
- McKusick-Nathans Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Garry R Cutting
- McKusick-Nathans Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Neeraj Sharma
- McKusick-Nathans Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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22
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Clinical and Genetic Characterisation of Cystic Fibrosis Patients in Latvia: A Twenty-Five-Year Experience. Diagnostics (Basel) 2022; 12:diagnostics12112893. [PMID: 36428953 PMCID: PMC9689702 DOI: 10.3390/diagnostics12112893] [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: 10/26/2022] [Revised: 11/11/2022] [Accepted: 11/18/2022] [Indexed: 11/23/2022] Open
Abstract
Cystic fibrosis (CF) is the most common life-limiting genetic disorder in European descent populations. It is caused by pathogenic variants in the CFTR gene, and inheritance is autosomal recessive. This study provides an up-to-date, comprehensive estimation of the distribution of CFTR pathogenic variants in Latvia and their phenotypic characteristics. It also reports the first results of the CF newborn screening programme following its implementation in 2019. We analysed the clinical and molecular data of CF patients treated at the only tertiary hospital in Latvia providing specialised healthcare for the disorder. Between 1997 and 2022, 66 CF patients from 62 families were diagnosed based on symptoms or a molecular confirmation (six patients were diagnosed through the CF newborn screening programme). F508del was identified in 70.5% of all CF chromosomes. Known variants were identified in more than one family: dele2,3, R1006H, L1335P, W57R, R553X, 2143delT and 3849+10kb C>T (legacy names used). Furthermore, two novel variants were identified, namely, c.503C>A p.(Ser168Ter) and c.(743+1_744-1)_(1584+1_1585-1)del p.(?). The available follow-up results indicated that Latvian CF patients demonstrated similar tendencies to CF patients worldwide. The oldest age at diagnosis prior to the implementation of the CF newborn screening programme was 14 years. We provide here, for the first time, a comprehensive description of Latvian CF patients. An improvement in the healthcare of CF patients over time, including access to diagnosis, is evident. Two novel CF-causing variants are reported, and F508del is the most frequently occurring variant in the population, thus suggesting that F508del screening should be followed by the testing of the full CFTR gene.
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23
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Bentur L, Pollak M. Trikafta—Extending Its Success to Less Common Mutations. J Pers Med 2022; 12:jpm12091528. [PMID: 36143317 PMCID: PMC9504046 DOI: 10.3390/jpm12091528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 09/15/2022] [Indexed: 11/16/2022] Open
Affiliation(s)
- Lea Bentur
- Pediatric Pulmonary Institute, Ruth Children’s Hospital, Rambam Health Care Center, Haifa 31096, Israel
- Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 32000, Israel
- Correspondence: (L.B.); (M.P.)
| | - Mordechai Pollak
- Pediatric Pulmonary Institute, Ruth Children’s Hospital, Rambam Health Care Center, Haifa 31096, Israel
- Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 32000, Israel
- Correspondence: (L.B.); (M.P.)
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24
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Januska MN, Langfelder-Schwind E, Berdella MN. Overcoming health disparities in access to CFTR modulator therapies: One child's journey with cystic fibrosis. Pediatr Pulmonol 2022; 57:2273-2275. [PMID: 35637164 DOI: 10.1002/ppul.26022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 05/25/2022] [Accepted: 05/29/2022] [Indexed: 11/06/2022]
Affiliation(s)
- Megan N Januska
- Department of Pulmonary, Critical Care, and Sleep Medicine, The Cystic Fibrosis Center at Mount Sinai Beth Israel, New York, New York, USA.,Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Elinor Langfelder-Schwind
- Department of Pulmonary, Critical Care, and Sleep Medicine, The Cystic Fibrosis Center at Mount Sinai Beth Israel, New York, New York, USA
| | - Maria N Berdella
- Department of Pulmonary, Critical Care, and Sleep Medicine, The Cystic Fibrosis Center at Mount Sinai Beth Israel, New York, New York, USA
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25
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Bowling A, Eastman A, Merlo C, Lin G, West N, Patel S, Cutting G, Sharma N. Downstream Alternate Start Site Allows N-Terminal Nonsense Variants to Escape NMD and Results in Functional Recovery by Readthrough and Modulator Combination. J Pers Med 2022; 12:jpm12091448. [PMID: 36143233 PMCID: PMC9504986 DOI: 10.3390/jpm12091448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 08/26/2022] [Accepted: 08/31/2022] [Indexed: 11/23/2022] Open
Abstract
Genetic variants that introduce premature termination codons (PTCs) have remained difficult to therapeutically target due to lack of protein product. Nonsense mediated mRNA decay (NMD) targets PTC-bearing transcripts to reduce the potentially damaging effects of truncated proteins. Readthrough compounds have been tested on PTC-generating variants in attempt to permit translation through a premature stop. However, readthrough compounds have not proved efficacious in a clinical setting due to lack of stable mRNA. Here, we investigate N-terminal variants in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which have been shown to escape NMD, potentially through a mechanism of alternative translation initiation at downstream AUG codons. We hypothesized that N-terminal variants in CFTR that evade NMD will produce stable transcript, allowing CFTR function to be restored by a combination of readthrough and protein modulator therapy. We investigate this using two cell line models expressing CFTR-expression minigenes (EMG; HEK293s and CFBEs) and primary human nasal epithelial (NE) cells, and we test readthrough compounds G418 and ELX-02 in combination with CFTR protein modulators. HEK293 cells expressing the variants E60X and L88X generate CFTR-specific core glycosylated products that are consistent with downstream translation initiation. Mutation of downstream methionines at codons 150 and 152 does not result in changes in CFTR protein processing in cells expressing L88X-CFTR-EMG. However, mutation of methionine at 265 results in loss of detectable CFTR protein in cells expressing E60X, L88X, and Y122X CFTR-EMGs, indicating that downstream translation initiation is occurring at the AUG codon at position M265. In HEK293 stable cells harboring L88X, treatment with readthrough compounds alone allows for formation of full-length, but misfolded CFTR protein. Upon addition of protein modulators in combination with readthrough, we observe formation of mature, complex-glycosylated CFTR. In CFBE and NE cells, addition of readthrough ELX-02 and modulator therapy results in substantial recovery of CFTR function. Our work indicates that N-terminal variants generate stable CFTR transcript due to translation initiation at a downstream AUG codon. Thus, individuals with CF bearing 5′ nonsense variants that evade NMD are ideal candidates for treatment with clinically safe readthrough compounds and modulator therapy.
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Affiliation(s)
- Alyssa Bowling
- McKusick-Nathans Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Alice Eastman
- McKusick-Nathans Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Christian Merlo
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins Hospital, Baltimore, MD 21205, USA
| | - Gabrielle Lin
- McKusick-Nathans Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Natalie West
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins Hospital, Baltimore, MD 21205, USA
| | - Shivani Patel
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins Hospital, Baltimore, MD 21205, USA
| | - Garry Cutting
- McKusick-Nathans Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Neeraj Sharma
- McKusick-Nathans Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Correspondence:
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26
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Advances in Preclinical In Vitro Models for the Translation of Precision Medicine for Cystic Fibrosis. J Pers Med 2022; 12:jpm12081321. [PMID: 36013270 PMCID: PMC9409685 DOI: 10.3390/jpm12081321] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 08/12/2022] [Accepted: 08/16/2022] [Indexed: 11/19/2022] Open
Abstract
The development of preclinical in vitro models has provided significant progress to the studies of cystic fibrosis (CF), a frequently fatal monogenic disease caused by mutations in the gene encoding the CF transmembrane conductance regulator (CFTR) protein. Numerous cell lines were generated over the last 30 years and they have been instrumental not only in enhancing the understanding of CF pathological mechanisms but also in developing therapies targeting the underlying defects in CFTR mutations with further validation in patient-derived samples. Furthermore, recent advances toward precision medicine in CF have been made possible by optimizing protocols and establishing novel assays using human bronchial, nasal and rectal tissues, and by progressing from two-dimensional monocultures to more complex three-dimensional culture platforms. These models also enable to potentially predict clinical efficacy and responsiveness to CFTR modulator therapies at an individual level. In parallel, advanced systems, such as induced pluripotent stem cells and organ-on-a-chip, continue to be developed in order to more closely recapitulate human physiology for disease modeling and drug testing. In this review, we have highlighted novel and optimized cell models that are being used in CF research to develop novel CFTR-directed therapies (or alternative therapeutic interventions) and to expand the usage of existing modulator drugs to common and rare CF-causing mutations.
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27
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Molecular Basis for Variations in the Sensitivity of Pathogenic Rhodopsin Variants to 9-cis-Retinal. J Biol Chem 2022; 298:102266. [PMID: 35850308 PMCID: PMC9399271 DOI: 10.1016/j.jbc.2022.102266] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 07/11/2022] [Accepted: 07/13/2022] [Indexed: 11/24/2022] Open
Abstract
Over 100 mutations in the rhodopsin gene have been linked to a spectrum of retinopathies that include retinitis pigmentosa and congenital stationary night blindness. Though most of these variants exhibit a loss of function, the molecular defects caused by these underlying mutations vary considerably. In this work, we utilize deep mutational scanning to quantitatively compare the plasma membrane expression of 123 known pathogenic rhodopsin variants in the presence and absence of the stabilizing cofactor 9-cis-retinal. We identify 69 retinopathy variants, including 20 previously uncharacterized variants, that exhibit diminished plasma membrane expression in HEK293T cells. Of these apparent class II variants, 67 exhibit a measurable increase in expression in the presence of 9-cis-retinal. However, the magnitude of the response to this molecule varies considerably across this spectrum of mutations. Evaluation of the observed shifts relative to thermodynamic estimates for the coupling between binding and folding suggests underlying differences in stability constrains the magnitude of their response to retinal. Nevertheless, estimates from computational modeling suggest that many of the least sensitive variants also directly compromise binding. Finally, we evaluate the functional properties of three previous uncharacterized, retinal-sensitive variants (ΔN73, S131P, and R135G) and show that two of these retain residual function in vitro. Together, our results provide a comprehensive experimental characterization of the proteostatic properties of retinopathy variants and their response to retinal.
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28
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Wang C, Anglès F, Balch WE. Triangulating variation in the population to define mechanisms for precision management of genetic disease. Structure 2022; 30:1190-1207.e5. [PMID: 35714602 PMCID: PMC9357173 DOI: 10.1016/j.str.2022.05.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 04/18/2022] [Accepted: 05/17/2022] [Indexed: 10/18/2022]
Abstract
To understand mechanistically how the protein fold is shaped by therapeutics to inform precision management of disease, we developed variation-capture (VarC) mapping. VarC triangulates sparse sequence variation information found in the population using Gaussian process regression (GPR)-based machine learning to define the combined pairwise-residue interactions contributing to dynamic protein function in the individual in response to therapeutics. Using VarC mapping, we now reveal the pairwise-residue covariant relationships across the entire protein fold of cystic fibrosis (CF) transmembrane conductance regulator (CFTR) to define the molecular mechanisms of clinically approved CF chemical modulators. We discover an energetically destabilized covariant core containing a di-acidic YKDAD endoplasmic reticulum (ER) exit code that is only weakly corrected by current therapeutics. Our results illustrate that VarC provides a generalizable tool to triangulate information from genetic variation in the population to mechanistically discover therapeutic strategies that guide precision management of the individual.
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Affiliation(s)
- Chao Wang
- Department of Molecular Medicine, Scripps Research, La Jolla, CA 92037, USA
| | - Frédéric Anglès
- Department of Molecular Medicine, Scripps Research, La Jolla, CA 92037, USA
| | - William E Balch
- Department of Molecular Medicine, Scripps Research, La Jolla, CA 92037, USA.
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29
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Wong SL, Awatade NT, Astore MA, Allan KM, Carnell MJ, Slapetova I, Chen PC, Setiadi J, Pandzic E, Fawcett LK, Widger JR, Whan RM, Griffith R, Ooi CY, Kuyucak S, Jaffe A, Waters SA. Molecular Dynamics and Theratyping in Airway and Gut Organoids Reveal R352Q-CFTR Conductance Defect. Am J Respir Cell Mol Biol 2022; 67:99-111. [PMID: 35471184 PMCID: PMC9273222 DOI: 10.1165/rcmb.2021-0337oc] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
A significant challenge to making targeted cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapies accessible to all individuals with cystic fibrosis (CF) are many mutations in the CFTR gene that can cause CF, most of which remain uncharacterized. Here, we characterized the structural and functional defects of the rare CFTR mutation R352Q, with a potential role contributing to intrapore chloride ion permeation, in patient-derived cell models of the airway and gut. CFTR function in differentiated nasal epithelial cultures and matched intestinal organoids was assessed using an ion transport assay and forskolin-induced swelling assay, respectively. CFTR potentiators (VX-770, GLPG1837, and VX-445) and correctors (VX-809, VX-445, with or without VX-661) were tested. Data from R352Q-CFTR were compared with data of 20 participants with mutations with known impact on CFTR function. R352Q-CFTR has residual CFTR function that was restored to functional CFTR activity by CFTR potentiators but not the corrector. Molecular dynamics simulations of R352Q-CFTR were carried out, which indicated the presence of a chloride conductance defect, with little evidence supporting a gating defect. The combination approach of in vitro patient-derived cell models and in silico molecular dynamics simulations to characterize rare CFTR mutations can improve the specificity and sensitivity of modulator response predictions and aid in their translational use for CF precision medicine.
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Affiliation(s)
- Sharon L Wong
- University of New South Wales, 7800, School of Women's and Children's Health, Faculty of Medicine, Sydney, New South Wales, Australia.,University of New South Wales, 7800, Molecular and Integrative Cystic Fibrosis Research Centre (miCF_RC), Sydney, New South Wales, Australia
| | - Nikhil T Awatade
- University of New South Wales, 7800, School of Women's and Children's Health, Faculty of Medicine, Sydney, New South Wales, Australia.,University of New South Wales, 7800, Molecular and Integrative Cystic Fibrosis Research Centre (miCF_RC), Sydney, New South Wales, Australia
| | - Miro A Astore
- The University of Sydney, 4334, School of Physics, Sydney, New South Wales, Australia
| | - Katelin M Allan
- University of New South Wales, 7800, School of Women's and Children's Health, Faculty of Medicine, Sydney, New South Wales, Australia.,University of New South Wales, 7800, Molecular and Integrative Cystic Fibrosis Research Centre (miCF_RC), Sydney, New South Wales, Australia
| | - Michael J Carnell
- University of New South Wales, 7800, Biomedical Imaging Facility, Mark Wainwright Analytical Centre, Sydney, New South Wales, Australia
| | - Iveta Slapetova
- University of New South Wales, 7800, Biomedical Imaging Facility, Mark Wainwright Analytical Centre, Sydney, New South Wales, Australia
| | - Po-Chia Chen
- The University of Sydney, 4334, School of Physics, Sydney, New South Wales, Australia
| | - Jeffry Setiadi
- The University of Sydney, 4334, School of Physics, Sydney, New South Wales, Australia
| | - Elvis Pandzic
- University of New South Wales, 7800, Biomedical Imaging Facility, Mark Wainwright Analytical Cen, Sydney, New South Wales, Australia
| | - Laura K Fawcett
- University of New South Wales, 7800, School of Women's and Children's Health, Faculty of Medicine, Sydney, New South Wales, Australia.,University of New South Wales, 7800, Molecular and Integrative Cystic Fibrosis Research Centre (miCF_RC), Sydney, New South Wales, Australia.,Sydney Children's Hospital Randwick, 63623, Department of Respiratory Medicine, Randwick, New South Wales, Australia
| | - John R Widger
- University of New South Wales, 7800, School of Women's and Children's Health, Faculty of Medicine, Sydney, New South Wales, Australia.,University of New South Wales, 7800, Molecular and Integrative Cystic Fibrosis Research Centre (miCF_RC), Sydney, New South Wales, Australia.,Sydney Children's Hospital Randwick, 63623, Department of Respiratory Medicine, Randwick, New South Wales, Australia
| | - Renee M Whan
- University of New South Wales, 7800, Biomedical Imaging Facility, Mark Wainwright Analytical Centre, Sydney, New South Wales, Australia
| | - Renate Griffith
- University of New South Wales, 7800, School of Chemistry, Sydney, New South Wales, Australia
| | - Chee Y Ooi
- Sydney Children's Hospital Randwick, Gastroenterology, Sydney, New South Wales, Australia
| | - Serdar Kuyucak
- The University of Sydney, 4334, School of Physics, Sydney, New South Wales, Australia
| | - Adam Jaffe
- Sydney Children`s Hospital, Respiratory Medicine, Sydney, New South Wales, Australia.,University of New South Wales, 7800, School of Women`s and Children`s Health, Sydney, New South Wales, Australia
| | - Shafagh A Waters
- Sydney Children's Hospital, Department of Respiratory Medicine, Sydney, New South Wales, Australia.,Univeristy of New South Wales, School of Women's and Children's Health, Sydney, New South Wales, Australia;
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30
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Anglès F, Wang C, Balch WE. Spatial covariance analysis reveals the residue-by-residue thermodynamic contribution of variation to the CFTR fold. Commun Biol 2022; 5:356. [PMID: 35418593 PMCID: PMC9008016 DOI: 10.1038/s42003-022-03302-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 03/21/2022] [Indexed: 12/21/2022] Open
Abstract
Although the impact of genome variation on the thermodynamic properties of function on the protein fold has been studied in vitro, it remains a challenge to assign these relationships across the entire polypeptide sequence in vivo. Using the Gaussian process regression based principle of Spatial CoVariance, we globally assign on a residue-by-residue basis the biological thermodynamic properties that contribute to the functional fold of CFTR in the cell. We demonstrate the existence of a thermodynamically sensitive region of the CFTR fold involving the interface between NBD1 and ICL4 that contributes to its export from endoplasmic reticulum. At the cell surface a new set of residues contribute uniquely to the management of channel function. These results support a general 'quality assurance' view of global protein fold management as an SCV principle describing the differential pre- and post-ER residue interactions contributing to compartmentalization of the energetics of the protein fold for function. Our results set the stage for future analyses of the quality systems managing protein sequence-to-function-to-structure broadly encompassing genome design leading to protein function in complex cellular relationships responsible for diversity and fitness in biology in response to the environment.
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Affiliation(s)
- Frédéric Anglès
- Scripps Research, Department of Molecular Medicine, 10550 North Torrey Pines Rd, La Jolla, CA, 92037, USA
| | - Chao Wang
- Scripps Research, Department of Molecular Medicine, 10550 North Torrey Pines Rd, La Jolla, CA, 92037, USA
| | - William E Balch
- Scripps Research, Department of Molecular Medicine, 10550 North Torrey Pines Rd, La Jolla, CA, 92037, USA.
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31
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McDonald EF, Sabusap CMP, Kim M, Plate L. Distinct proteostasis states drive pharmacologic chaperone susceptibility for Cystic Fibrosis Transmembrane Conductance Regulator misfolding mutants. Mol Biol Cell 2022; 33:ar62. [PMID: 35389766 PMCID: PMC9561855 DOI: 10.1091/mbc.e21-11-0578] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Pharmacological chaperones represent a class of therapeutic compounds for treating protein misfolding diseases. One of the most prominent examples is the FDA-approved pharmacological chaperone lumacaftor (VX-809), which has transformed cystic fibrosis (CF) therapy. CF is a fatal disease caused by mutations in the CF transmembrane conductance regulator (CFTR). VX-809 corrects folding of F508del CFTR, the most common patient mutation, yet F508del exhibits only mild VX-809 response. In contrast, rarer mutations P67L and L206W are hyperresponsive to VX-809, while G85E is nonresponsive. Despite the clinical success of VX-809, the mechanistic origin for the distinct susceptibility of mutants remains unclear. Here we use interactomics to characterize the impact of VX-809 on proteostasis interactions of P67L and L206W and compare these with F508del and G85E. We determine that hyperresponsive mutations P67L and L206W exhibit decreased interactions with proteasomal and autophagy degradation machinery compared with F508del and G85E. We then show inhibiting the proteasome attenuates P67L and L206W VX-809 response. Our data suggest a previously unidentified but required role for protein degradation in VX-809 correction. Furthermore, we present an approach for identifying proteostasis characteristics of mutant-specific therapeutic response to pharmacological chaperones.
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Affiliation(s)
| | | | - Minsoo Kim
- Department of Chemistry.,Chemical and Physical Biology Program
| | - Lars Plate
- Department of Chemistry.,Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
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Kim YJ, Sivetz N, Layne J, Voss DM, Yang L, Zhang Q, Krainer AR. Exon-skipping antisense oligonucleotides for cystic fibrosis therapy. Proc Natl Acad Sci U S A 2022; 119:e2114858118. [PMID: 35017301 PMCID: PMC8784140 DOI: 10.1073/pnas.2114858118] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 11/16/2021] [Indexed: 11/25/2022] Open
Abstract
Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene cause cystic fibrosis (CF), and the CFTR-W1282X nonsense mutation causes a severe form of CF. Although Trikafta and other CFTR-modulation therapies benefit most CF patients, targeted therapy for patients with the W1282X mutation is lacking. The CFTR-W1282X protein has residual activity but is expressed at a very low level due to nonsense-mediated messenger RNA (mRNA) decay (NMD). NMD-suppression therapy and read-through therapy are actively being researched for CFTR nonsense mutants. NMD suppression could increase the mutant CFTR mRNA, and read-through therapies may increase the levels of full-length CFTR protein. However, these approaches have limitations and potential side effects: because the NMD machinery also regulates the expression of many normal mRNAs, broad inhibition of the pathway is not desirable, and read-through drugs are inefficient partly because the mutant mRNA template is subject to NMD. To bypass these issues, we pursued an exon-skipping antisense oligonucleotide (ASO) strategy to achieve gene-specific NMD evasion. A cocktail of two splice-site-targeting ASOs induced the expression of CFTR mRNA without the premature-termination-codon-containing exon 23 (CFTR-Δex23), which is an in-frame exon. Treatment of human bronchial epithelial cells with this cocktail of ASOs that target the splice sites flanking exon 23 results in efficient skipping of exon 23 and an increase in CFTR-Δex23 protein. The splice-switching ASO cocktail increases the CFTR-mediated chloride current in human bronchial epithelial cells. Our results set the stage for developing an allele-specific therapy for CF caused by the W1282X mutation.
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Affiliation(s)
- Young Jin Kim
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724
- Graduate Program in Genetics, Stony Brook University, Stony Brook, NY 11794
- Medical Scientist Training Program, Stony Brook University School of Medicine, Stony Brook, NY 11794
| | - Nicole Sivetz
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724
| | - Jessica Layne
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724
| | - Dillon M Voss
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724
- Graduate Program in Genetics, Stony Brook University, Stony Brook, NY 11794
- Medical Scientist Training Program, Stony Brook University School of Medicine, Stony Brook, NY 11794
| | - Lucia Yang
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724
- Graduate Program in Genetics, Stony Brook University, Stony Brook, NY 11794
- Medical Scientist Training Program, Stony Brook University School of Medicine, Stony Brook, NY 11794
| | - Qian Zhang
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724
- Graduate Program in Molecular and Cell Biology, Stony Brook University, Stony Brook, NY 11794
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33
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Rare Trafficking CFTR Mutations Involve Distinct Cellular Retention Machineries and Require Different Rescuing Strategies. Int J Mol Sci 2021; 23:ijms23010024. [PMID: 35008443 PMCID: PMC8744605 DOI: 10.3390/ijms23010024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 12/17/2021] [Accepted: 12/18/2021] [Indexed: 12/12/2022] Open
Abstract
Most of the ~2100 CFTR variants so far reported are very rare and still uncharacterized regarding their cystic fibrosis (CF) disease liability. Since some may respond to currently approved modulators, characterizing their defect and response to these drugs is essential. Here we aimed characterizing the defect associated with four rare missense (likely Class II) CFTR variants and assess their rescue by corrector drugs. We produced CFBE cell lines stably expressing CFTR with W57G, R560S, H1079P and Q1100P, assessed their effect upon CFTR expression and maturation and their rescue by VX-661/VX-445 correctors. Results were validated by forskolin-induced swelling assay (FIS) using intestinal organoids from individuals bearing these variants. Finally, knock-down (KD) of genes previously shown to rescue F508del-CFTR was assessed on these mutants. Results show that all the variants preclude the production of mature CFTR, confirming them as Class II mutations. None of the variants responded to VX-661 but the combination rescued H1079P- and Q1100P-CFTR. The KD of factors that correct F508del-CFTR retention only marginally rescued R560S- and H1079P-CFTR. Overall, data evidence that Class II mutations induce distinct molecular defects that are neither rescued by the same corrector compounds nor recognized by the same cellular machinery, thus requiring personalized drug discovery initiatives.
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34
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Kumari D, Fisher EA, Brodsky JL. Hsp40s play distinct roles during the initial stages of apolipoprotein B biogenesis. Mol Biol Cell 2021; 33:ar15. [PMID: 34910568 PMCID: PMC9236142 DOI: 10.1091/mbc.e21-09-0436] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Apolipoprotein B (ApoB) is the primary component of atherogenic lipoproteins, which transport serum fats and cholesterol. Therefore, elevated levels of circulating ApoB are a primary risk factor for cardiovascular disease. During ApoB biosynthesis in the liver and small intestine under nutrient-rich conditions, ApoB cotranslationally translocates into the endoplasmic reticulum (ER) and is lipidated and ultimately secreted. Under lipid-poor conditions, ApoB is targeted for ER Associated Degradation (ERAD). Although prior work identified select chaperones that regulate ApoB biogenesis, the contributions of cytoplasmic Hsp40s are undefined. To this end, we screened ApoB-expressing yeast and determined that a class A ER-associated Hsp40, Ydj1, associates with and facilitates the ERAD of ApoB. Consistent with these results, a homologous Hsp40, DNAJA1, functioned similarly in rat hepatoma cells. DNAJA1 deficient cells also secreted hyperlipidated lipoproteins, in accordance with attenuated ERAD. In contrast to the role of DNAJA1 during ERAD, DNAJB1-a class B Hsp40-helped stabilize ApoB. Depletion of DNAJA1 and DNAJB1 also led to opposing effects on ApoB ubiquitination. These data represent the first example in which different Hsp40s exhibit disparate effects during regulated protein biogenesis in the ER, and highlight distinct roles that chaperones can play on a single ERAD substrate.
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Affiliation(s)
- Deepa Kumari
- Department of Biological Sciences, A320 Langley Hall, Fifth & Ruskin Ave, University of Pittsburgh, Pittsburgh, PA 15260 USA
| | - Edward A Fisher
- Department of Medicine, Leon H. Charney Division of Cardiology, Cardiovascular Research Center, New York University Grossman School of Medicine, New York, United States
| | - Jeffrey L Brodsky
- Department of Biological Sciences, A320 Langley Hall, Fifth & Ruskin Ave, University of Pittsburgh, Pittsburgh, PA 15260 USA
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35
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Laselva O, Bartlett C, Gunawardena TNA, Ouyang H, Eckford PDW, Moraes TJ, Bear CE, Gonska T. Rescue of multiple class II CFTR mutations by elexacaftor+tezacaftor+ivacaftor mediated in part by the dual activities of elexacaftor as both corrector and potentiator. Eur Respir J 2021; 57:2002774. [PMID: 33303536 PMCID: PMC8209484 DOI: 10.1183/13993003.02774-2020] [Citation(s) in RCA: 92] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Accepted: 11/20/2020] [Indexed: 12/20/2022]
Abstract
Positive results in pre-clinical studies of the triple combination of elexacaftor, tezacaftor and ivacaftor, performed in airway epithelial cell cultures obtained from patients harbouring the class II cystic fibrosis transmembrane conductance regulator (CFTR) mutation F508del-CFTR, translated to impressive clinical outcomes for subjects carrying this mutation in clinical trials and approval of Trikafta.Encouraged by this correlation, we were prompted to evaluate the effect of the elexacaftor, tezacaftor and ivacaftor triple combination on primary nasal epithelial cultures obtained from individuals with rare class II CF-causing mutations (G85E, M1101K and N1303K) for which Trikafta is not approved.Cultures from individuals homozygous for M1101K responded better than cultures harbouring G85E and N1303K after treatment with the triple combination with respect to improvement in regulated channel function and protein processing. A similar genotype-specific effect of the triple combination was observed when the different mutations were expressed in HEK293 cells, supporting the hypothesis that these modulators may act directly on the mutant proteins. Detailed studies in nasal cultures and HEK293 cells showed that the corrector, elexacaftor, exhibited dual activity as both corrector and potentiator, and suggested that the potentiator activity contributes to its pharmacological activity.These pre-clinical studies using nasal epithelial cultures identified mutation genotypes for which elexacaftor, tezacaftor and ivacaftor may produce clinical responses that are comparable to, or inferior to, those observed for F508del-CFTR.
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Affiliation(s)
- Onofrio Laselva
- Programme in Molecular Medicine, The Hospital for Sick Children, Toronto, ON, Canada
- Dept of Physiology, University of Toronto, Toronto, ON, Canada
| | - Claire Bartlett
- Programme in Translational Medicine, The Hospital for Sick Children, Toronto, ON, Canada
| | - Tarini N A Gunawardena
- Programme in Molecular Medicine, The Hospital for Sick Children, Toronto, ON, Canada
- Programme in Translational Medicine, The Hospital for Sick Children, Toronto, ON, Canada
| | - Hong Ouyang
- Programme in Translational Medicine, The Hospital for Sick Children, Toronto, ON, Canada
| | - Paul D W Eckford
- Programme in Molecular Medicine, The Hospital for Sick Children, Toronto, ON, Canada
| | - Theo J Moraes
- Programme in Translational Medicine, The Hospital for Sick Children, Toronto, ON, Canada
- Dept of Paediatrics, University of Toronto, Toronto, ON, Canada
| | - Christine E Bear
- Programme in Molecular Medicine, The Hospital for Sick Children, Toronto, ON, Canada
- Dept of Physiology, University of Toronto, Toronto, ON, Canada
- Dept of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Tanja Gonska
- Programme in Translational Medicine, The Hospital for Sick Children, Toronto, ON, Canada
- Dept of Paediatrics, University of Toronto, Toronto, ON, Canada
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36
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Phenotyping Rare CFTR Mutations Reveal Functional Expression Defects Restored by TRIKAFTA TM. J Pers Med 2021; 11:jpm11040301. [PMID: 33920764 PMCID: PMC8071105 DOI: 10.3390/jpm11040301] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 04/12/2021] [Accepted: 04/13/2021] [Indexed: 12/15/2022] Open
Abstract
The rare Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) mutations, c.1826A > G (H609R) and c.3067_3072delATAGTG (I1023_V1024del), are associated with severe lung disease. Despite the existence of four CFTR targeted therapies, none have been approved for individuals with these mutations because the associated molecular defects were not known. In this study we examined the consequences of these mutations on protein processing and channel function in HEK293 cells. We found that, similar to F508del, H609R and I1023_V1024del-CFTR exhibited reduced protein processing and altered channel function. Because the I1023_V1024del mutation can be linked with the mutation, I148T, we also examined the protein conferred by transfection of a plasmid bearing both mutations. Interestingly, together with I148T, there was no further reduction in channel function exhibited by I1023-V1024del. Both H609R and I1023_V1024del failed to exhibit significant correction of their functional expression with lumacaftor and ivacaftor. In contrast, the triple modulator combination found in TRIKAFTATM, i.e., tezacaftor, elexacaftor and ivacaftor rescued trafficking and function of both of these mutants. These in-vitro findings suggest that patients harbouring H609R or I1023_V1024del, alone or with I148T, may benefit clinically from treatment with TRIKAFTATM.
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37
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Lopes-Pacheco M, Pedemonte N, Veit G. Discovery of CFTR modulators for the treatment of cystic fibrosis. Expert Opin Drug Discov 2021; 16:897-913. [PMID: 33823716 DOI: 10.1080/17460441.2021.1912732] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
INTRODUCTION Cystic fibrosis (CF) is a life-threatening inherited disease caused by mutations in the gene encoding the CF transmembrane conductance regulator (CFTR) protein, an anion channel expressed at the apical membrane of secretory epithelia. CF leads to multiorgan dysfunction with progressive deterioration of lung function being the major cause of untimely death. Conventional CF therapies target only symptoms and consequences downstream of the primary genetic defect and the current life expectancy and quality of life of these individuals are still very limited. AREA COVERED CFTR modulator drugs are novel-specialized therapies that enhance or even restore functional expression of CFTR mutants and have been approved for clinical use for individuals with specific CF genotypes. This review summarizes classical approaches used for the pre-clinical development of CFTR correctors and potentiators as well as emerging strategies aiming to accelerate modulator development and expand theratyping efforts. EXPERT OPINION Highly effective CFTR modulator drugs are expected to deeply modify the disease course for the majority of individuals with CF. A multitude of experimental approaches have been established to accelerate the development of novel modulators. CF patient-derived specimens are valuable cell models to predict therapeutic effectiveness of existing (and novel) modulators in a precision medicine approach.
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Affiliation(s)
| | | | - Guido Veit
- Department of Physiology, McGill University, Montréal, Canada
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38
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Treggiari D, Kleinfelder K, Bertini M, Tridello G, Fedrigo A, Pintani E, Iansa P, Casiraghi A, Minghetti P, Cipolli M, Sorio C, Melotti P. Optical Measurements of Sweat for in Vivo Quantification of CFTR Function in Individual Sweat Glands. J Cyst Fibros 2021; 20:824-827. [PMID: 33814321 DOI: 10.1016/j.jcf.2021.03.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 02/01/2021] [Accepted: 03/06/2021] [Indexed: 11/25/2022]
Abstract
Optical measurement of CFTR-dependent sweat secretion stimulated by a beta-adrenergic cocktail (C-phase) vs. CFTR-independent sweat secretion induced by methacholine (M-phase) can discriminate cystic fibrosis (CF) patientts from controls and healthy carriers by the ratio of sweat rate in the C-phase vs. the M-phase (C/M ratio). However, image analysis is experimentally demanding and time-consuming. Here, sweat droplet number (SDN) in the C-phase, corresponding to the number of sweat-secreting glands, was a statistically significant predictor for detecting the effects of CFTR-targeted therapy. We show that in 44 non-CF subjects and 110 CF patients, SDN in the C-phase provides a linear readout of CFTR function that is more sensitive than that using the C/M ratio. In CF patients, increased SDN in the C-phase during treatment with (LUMA/IVA) was associated with a trend toward improved lung function (FEV1). Our method is suitable for multicenter monitoring of the effects of CFTR modulators.
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Affiliation(s)
- Davide Treggiari
- Cystic Fibrosis Centre, Azienda Ospedaliera Universitaria Integrata Verona, piazzale Stefani, 1, 37126 Verona, Italy.
| | - Karina Kleinfelder
- Department of Medicine, University of Verona, Division of General Pathology, Strada Le Grazie 8, 37134 Verona, Italy.
| | - Marina Bertini
- Cystic Fibrosis Centre, Azienda Ospedaliera Universitaria Integrata Verona, piazzale Stefani, 1, 37126 Verona, Italy.
| | - Gloria Tridello
- Cystic Fibrosis Centre, Azienda Ospedaliera Universitaria Integrata Verona, piazzale Stefani, 1, 37126 Verona, Italy.
| | - Arianna Fedrigo
- Department of Medicine, University of Verona, Division of General Pathology, Strada Le Grazie 8, 37134 Verona, Italy.
| | - Emily Pintani
- Cystic Fibrosis Centre, Azienda Ospedaliera Universitaria Integrata Verona, piazzale Stefani, 1, 37126 Verona, Italy.
| | - Patrizia Iansa
- Cystic Fibrosis Centre, Azienda Ospedaliera Universitaria Integrata Verona, piazzale Stefani, 1, 37126 Verona, Italy.
| | - Antonella Casiraghi
- Department of Pharmaceutical Sciences, Università degli Studi di Milano, via G. Colombo 71, Milan, 20133, Italy.
| | - Paola Minghetti
- Department of Pharmaceutical Sciences, Università degli Studi di Milano, via G. Colombo 71, Milan, 20133, Italy.
| | - Marco Cipolli
- Cystic Fibrosis Centre, Azienda Ospedaliera Universitaria Integrata Verona, piazzale Stefani, 1, 37126 Verona, Italy.
| | - Claudio Sorio
- Department of Medicine, University of Verona, Division of General Pathology, Strada Le Grazie 8, 37134 Verona, Italy.
| | - Paola Melotti
- Cystic Fibrosis Centre, Azienda Ospedaliera Universitaria Integrata Verona, piazzale Stefani, 1, 37126 Verona, Italy.
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Sabusap CM, Joshi D, Simhaev L, Oliver KE, Senderowitz H, van Willigen M, Braakman I, Rab A, Sorscher EJ, Hong JS. The CFTR P67L variant reveals a key role for N-terminal lasso helices in channel folding, maturation, and pharmacologic rescue. J Biol Chem 2021; 296:100598. [PMID: 33781744 PMCID: PMC8102917 DOI: 10.1016/j.jbc.2021.100598] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 03/15/2021] [Accepted: 03/25/2021] [Indexed: 12/14/2022] Open
Abstract
Patients with cystic fibrosis (CF) harboring the P67L variant in the cystic fibrosis transmembrane conductance regulator (CFTR) often exhibit a typical CF phenotype, including severe respiratory compromise. This rare mutation (reported in <300 patients worldwide) responds robustly to CFTR correctors, such as lumacaftor and tezacaftor, with rescue in model systems that far exceed what can be achieved for the archetypical CFTR mutant F508del. However, the specific molecular consequences of the P67L mutation are poorly characterized. In this study, we conducted biochemical measurements following low-temperature growth and/or intragenic suppression, which suggest a mechanism underlying P67L that (1) shares key pathogenic features with F508del, including off-pathway (non-native) folding intermediates, (2) is linked to folding stability of nucleotide-binding domains 1 and 2, and (3) demonstrates pharmacologic rescue that requires domains in the carboxyl half of the protein. We also investigated the "lasso" helices 1 and 2, which occur immediately upstream of P67. Based on limited proteolysis, pulse chase, and molecular dynamics analysis of full-length CFTR and a series of deletion constructs, we argue that P67L and other maturational processing (class 2) defects impair the integrity of the lasso motif and confer misfolding of downstream domains. Thus, amino-terminal missense variants elicit a conformational change throughout CFTR that abrogates maturation while providing a robust substrate for pharmacologic repair.
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Affiliation(s)
- Carleen Mae Sabusap
- Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Disha Joshi
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Luba Simhaev
- Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel
| | - Kathryn E Oliver
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA
| | | | - Marcel van Willigen
- Department of Cellular Protein Chemistry, Utrecht University, Utrecht, Netherlands
| | - Ineke Braakman
- Department of Cellular Protein Chemistry, Utrecht University, Utrecht, Netherlands
| | - Andras Rab
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Eric J Sorscher
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA.
| | - Jeong S Hong
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA
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40
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Ramalho AS, Fürstová E, Vonk AM, Ferrante M, Verfaillie C, Dupont L, Boon M, Proesmans M, Beekman JM, Sarouk I, Vazquez Cordero C, Vermeulen F, De Boeck K. Correction of CFTR function in intestinal organoids to guide treatment of cystic fibrosis. Eur Respir J 2021; 57:13993003.02426-2019. [PMID: 32747394 DOI: 10.1183/13993003.02426-2019] [Citation(s) in RCA: 63] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 06/29/2020] [Indexed: 11/05/2022]
Abstract
RATIONALE Given the vast number of cystic fibrosis transmembrane conductance regulator (CFTR) mutations, biomarkers predicting benefit from CFTR modulator therapies are needed for subjects with cystic fibrosis (CF). OBJECTIVES To study CFTR function in organoids of subjects with common and rare CFTR mutations and evaluate correlations between CFTR function and clinical data. METHODS Intestinal organoids were grown from rectal biopsies in a cohort of 97 subjects with CF. Residual CFTR function was measured by quantifying organoid swelling induced by forskolin and response to modulators by quantifying organoid swelling induced by CFTR correctors, potentiator and their combination. Organoid data were correlated with clinical data from the literature. RESULTS Across 28 genotypes, residual CFTR function correlated (r2=0.87) with sweat chloride values. When studying the same genotypes, CFTR function rescue by CFTR modulators in organoids correlated tightly with mean improvement in lung function (r2=0.90) and sweat chloride (r2=0.95) reported in clinical trials. We identified candidate genotypes for modulator therapy, such as E92K, Q237E, R334W and L159S. Based on organoid results, two subjects started modulator treatment: one homozygous for complex allele Q359K_T360K, and the second with mutation E60K. Both subjects had major clinical benefit. CONCLUSIONS Measurements of residual CFTR function and rescue of function by CFTR modulators in intestinal organoids correlate closely with clinical data. Our results for reference genotypes concur with previous results. CFTR function measured in organoids can be used to guide precision medicine in patients with CF, positioning organoids as a potential in vitro model to bring treatment to patients carrying rare CFTR mutations.
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Affiliation(s)
- Anabela S Ramalho
- Dept of Development and Regeneration, Woman and Child Unit, CF Research Lab, KU Leuven, Leuven, Belgium
| | - Eva Fürstová
- Dept of Pediatrics, 2nd Faculty of Medicine, Charles University and Motol University Hospital, Prague, Czech Republic
| | - Annelotte M Vonk
- Dept of Pediatric Pulmonology, Wilhelmina Children's Hospital, University Medical Centre, Utrecht, The Netherlands.,Regenerative Medicine Center, University Medical Centre, Utrecht, The Netherlands
| | - Marc Ferrante
- Dept of Chronic Diseases, Metabolism and Ageing, Translational Research Center for Gastrointestinal Disorders (TARGID), KU Leuven, Leuven, Belgium.,Dept of Gastroenterology and Hepatology, University Hospitals Leuven, Leuven, Belgium
| | - Catherine Verfaillie
- Dept of Development and Regeneration, Stem Cell Biology and Embryology, KU Leuven, Leuven, Belgium
| | - Lieven Dupont
- Dept of Chronic Diseases, Metabolism and Ageing; Pneumology, KU Leuven, Leuven, Belgium.,Dept of Respiratory Diseases, University Hospital of Leuven, Leuven, Belgium
| | - Mieke Boon
- Dept of Development and Regeneration, Woman and Child Unit, CF Research Lab, KU Leuven, Leuven, Belgium.,Dept of Pediatrics, Pediatric Pulmonology, University Hospital of Leuven, Leuven, Belgium
| | - Marijke Proesmans
- Dept of Development and Regeneration, Woman and Child Unit, CF Research Lab, KU Leuven, Leuven, Belgium.,Dept of Pediatrics, Pediatric Pulmonology, University Hospital of Leuven, Leuven, Belgium
| | - Jeffrey M Beekman
- Dept of Pediatric Pulmonology, Wilhelmina Children's Hospital, University Medical Centre, Utrecht, The Netherlands.,Regenerative Medicine Center, University Medical Centre, Utrecht, The Netherlands
| | - Ifat Sarouk
- Pulmonology Pediatrics and National CF Center Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel Hashomer, Israel
| | | | - Francois Vermeulen
- Dept of Development and Regeneration, Woman and Child Unit, CF Research Lab, KU Leuven, Leuven, Belgium.,Dept of Pediatrics, Pediatric Pulmonology, University Hospital of Leuven, Leuven, Belgium
| | - Kris De Boeck
- Dept of Development and Regeneration, Woman and Child Unit, CF Research Lab, KU Leuven, Leuven, Belgium.,Dept of Pediatrics, Pediatric Pulmonology, University Hospital of Leuven, Leuven, Belgium
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41
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Abstract
Pathogenic variants of the CFTR gene are responsible for a broad phenotypic spectrum characterized by malfunction of some exocrine tissues, with an autosomal recessive mode of inheritance. More than 2,000 variants, distributed throughout the CFTR gene, have been identified, with different effects on the gene and protein expression and function. Genotype-phenotype correlation studies have associated severe variants with a typical multi-organ form of cystic fibrosis, while mild variants are involved in monosymptomatic or adult-onset diseases, called CFTR-related disorders. However, the interpretation of rare variants remains challenging. This review presents an overview of the epidemiology of CFTR variants worldwide and in France and describes the functional classification. Finally, some frequent cystic fibrosis-causing and mild CFTR variants are used as example to depict the molecular pathology of the CFTR locus. Finally, we give the recommendations concerning nomenclature and classification that are useful for appropriate genetic counseling. © 2020 French Society of Pediatrics. Published by Elsevier Masson SAS. All rights reserved.
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Affiliation(s)
- C Bareil
- Laboratoire de Génétique Moléculaire, CHU de Montpellier, Montpellier, France
| | - A Bergougnoux
- Laboratoire de Génétique Moléculaire, CHU de Montpellier, Montpellier, France; EA7402 Laboratoire de Génétique de Maladies Rares, Institut Universitaire de Recherche Clinique, Université de Montpellier, Montpellier, France..
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42
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Prins S, Langron E, Hastings C, Hill EJ, Stefan AC, Griffin LD, Vergani P. Fluorescence assay for simultaneous quantification of CFTR ion-channel function and plasma membrane proximity. J Biol Chem 2020; 295:16529-16544. [PMID: 32934006 PMCID: PMC7864054 DOI: 10.1074/jbc.ra120.014061] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 08/21/2020] [Indexed: 11/21/2022] Open
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) is a plasma membrane anion channel that plays a key role in controlling transepithelial fluid movement. Excessive activation results in intestinal fluid loss during secretory diarrheas, whereas CFTR mutations underlie cystic fibrosis (CF). Anion permeability depends both on how well CFTR channels work (permeation/gating) and on how many are present at the membrane. Recently, treatments with two drug classes targeting CFTR-one boosting ion-channel function (potentiators) and the other increasing plasma membrane density (correctors)-have provided significant health benefits to CF patients. Here, we present an image-based fluorescence assay that can rapidly and simultaneously estimate both CFTR ion-channel function and the protein's proximity to the membrane. We monitor F508del-CFTR, the most common CF-causing variant, and confirm rescue by low temperature, CFTR-targeting drugs and second-site revertant mutation R1070W. In addition, we characterize a panel of 62 CF-causing mutations. Our measurements correlate well with published data (electrophysiology and biochemistry), further confirming validity of the assay. Finally, we profile effects of acute treatment with approved potentiator drug VX-770 on the rare-mutation panel. Mapping the potentiation profile on CFTR structures raises mechanistic hypotheses on drug action, suggesting that VX-770 might allow an open-channel conformation with an alternative arrangement of domain interfaces. The assay is a valuable tool for investigation of CFTR molecular mechanisms, allowing accurate inferences on gating/permeation. In addition, by providing a two-dimensional characterization of the CFTR protein, it could better inform development of single-drug and precision therapies addressing the root cause of CF disease.
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Affiliation(s)
- Stella Prins
- Department of Neuroscience, Physiology, and Pharmacology, University College London, London, United Kingdom
| | - Emily Langron
- Department of Neuroscience, Physiology, and Pharmacology, University College London, London, United Kingdom
| | - Cato Hastings
- CoMPLEX, University College London, London, United Kingdom
| | - Emily J Hill
- Department of Neuroscience, Physiology, and Pharmacology, University College London, London, United Kingdom
| | - Andra C Stefan
- Natural Sciences, University College London, London, United Kingdom
| | | | - Paola Vergani
- Department of Neuroscience, Physiology, and Pharmacology, University College London, London, United Kingdom.
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43
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Wambach JA, Yang P, Wegner DJ, Heins HB, Luke C, Li F, White FV, Cole FS. Functional Genomics of ABCA3 Variants. Am J Respir Cell Mol Biol 2020; 63:436-443. [PMID: 32692933 DOI: 10.1165/rcmb.2020-0034ma] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Rare or private, biallelic variants in the ABCA3 (ATP-binding cassette transporter A3) gene are the most common monogenic cause of lethal neonatal respiratory failure and childhood interstitial lung disease. Functional characterization of fewer than 10% of over 200 disease-associated ABCA3 variants (majority missense) suggests either disruption of ABCA3 protein trafficking (type I) or of ATPase-mediated phospholipid transport (type II). Therapies remain limited and nonspecific. A scalable platform is required for functional characterization of ABCA3 variants and discovery of pharmacologic correctors. To address this need, we first silenced the endogenous ABCA3 locus in A549 cells with CRISPR/Cas9 genome editing. Next, to generate a parent cell line (A549/ABCA3-/-) with a single recombination target site for genomic integration and stable expression of individual ABCA3 missense variant cDNAs, we used lentiviral-mediated integration of a LoxFAS cassette, FACS, and dilutional cloning. To assess the fidelity of this cell-based model, we compared functional characterization (ABCA3 protein processing, ABCA3 immunofluorescence colocalization with intracellular markers, ultrastructural vesicle phenotype) of two individual ABCA3 mutants (type I mutant, p.L101P; type II mutant, p.E292V) in A549/ABCA3-/- cells and in both A549 cells and primary, human alveolar type II cells that transiently express each cDNA after adenoviral-mediated transduction. We also confirmed pharmacologic rescue of ABCA3 variant-encoded mistrafficking and vesicle diameter in A549/ABCA3-/- cells that express p.G1421R (type I mutant). A549/ABCA3-/- cells provide a scalable, genetically versatile, physiologically relevant functional genomics platform for discovery of variant-specific mechanisms that disrupt ABCA3 function and for screening of potential ABCA3 pharmacologic correctors.
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Affiliation(s)
| | - Ping Yang
- Edward Mallinckrodt Department of Pediatrics
| | | | | | - Cliff Luke
- Edward Mallinckrodt Department of Pediatrics
| | - Fuhai Li
- Edward Mallinckrodt Department of Pediatrics.,Institute for Informatics, and
| | - Frances V White
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri
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44
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Kanner SA, Shuja Z, Choudhury P, Jain A, Colecraft HM. Targeted deubiquitination rescues distinct trafficking-deficient ion channelopathies. Nat Methods 2020; 17:1245-1253. [PMID: 33169015 PMCID: PMC9335257 DOI: 10.1038/s41592-020-00992-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 10/07/2020] [Indexed: 12/11/2022]
Abstract
Impaired protein stability/trafficking underlies diverse ion channelopathies and represents an unexploited unifying principle to develop common treatments for otherwise dissimilar diseases. Ubiquitination limits ion channel surface density, but targeting this pathway for basic study or therapy is challenging because of its prevalent role in proteostasis. We developed engineered deubiquitinases (enDUBs) that enable ubiquitin chain removal selectively from target proteins to rescue functional expression of disparate mutant ion channels underlying Long QT syndrome (LQT1) and cystic fibrosis (CF). In a LQT1 cardiomyocyte model, enDUB treatment restored delayed rectifier K+ currents and normalized action potential duration. CF-targeted enDUBs synergistically rescued common (F508del) and pharmacotherapy-resistant (N1303K) CF mutations when combined with the FDA-approved drugs, Orkambi and Trikafta. Altogether, targeted deubiquitination via enDUBs provides a powerful protein stabilization method that not only corrects diverse diseases caused by impaired ion channel trafficking, but also introduces a new tool for deconstructing the ubiquitin code in situ.
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Affiliation(s)
- Scott A Kanner
- Doctoral Program in Neurobiology and Behavior, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Zunaira Shuja
- Department of Physiology and Cellular Biophysics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Papiya Choudhury
- Department of Physiology and Cellular Biophysics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | | | - Henry M Colecraft
- Doctoral Program in Neurobiology and Behavior, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA. .,Department of Physiology and Cellular Biophysics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA. .,Department of Molecular Pharmacology and Therapeutics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA.
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45
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Joynt AT, Evans TA, Pellicore MJ, Davis-Marcisak EF, Aksit MA, Eastman AC, Patel SU, Paul KC, Osorio DL, Bowling AD, Cotton CU, Raraigh KS, West NE, Merlo CA, Cutting GR, Sharma N. Evaluation of both exonic and intronic variants for effects on RNA splicing allows for accurate assessment of the effectiveness of precision therapies. PLoS Genet 2020; 16:e1009100. [PMID: 33085659 PMCID: PMC7605713 DOI: 10.1371/journal.pgen.1009100] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 11/02/2020] [Accepted: 09/08/2020] [Indexed: 12/21/2022] Open
Abstract
Elucidating the functional consequence of molecular defects underlying genetic diseases enables appropriate design of therapeutic options. Treatment of cystic fibrosis (CF) is an exemplar of this paradigm as the development of CFTR modulator therapies has allowed for targeted and effective treatment of individuals harboring specific genetic variants. However, the mechanism of these drugs limits effectiveness to particular classes of variants that allow production of CFTR protein. Thus, assessment of the molecular mechanism of individual variants is imperative for proper assignment of these precision therapies. This is particularly important when considering variants that affect pre-mRNA splicing, thus limiting success of the existing protein-targeted therapies. Variants affecting splicing can occur throughout exons and introns and the complexity of the process of splicing lends itself to a variety of outcomes, both at the RNA and protein levels, further complicating assessment of disease liability and modulator response. To investigate the scope of this challenge, we evaluated splicing and downstream effects of 52 naturally occurring CFTR variants (exonic = 15, intronic = 37). Expression of constructs containing select CFTR intronic sequences and complete CFTR exonic sequences in cell line models allowed for assessment of RNA and protein-level effects on an allele by allele basis. Characterization of primary nasal epithelial cells obtained from individuals harboring splice variants corroborated in vitro data. Notably, we identified exonic variants that result in complete missplicing and thus a lack of modulator response (e.g. c.2908G>A, c.523A>G), as well as intronic variants that respond to modulators due to the presence of residual normally spliced transcript (e.g. c.4242+2T>C, c.3717+40A>G). Overall, our data reveals diverse molecular outcomes amongst both exonic and intronic variants emphasizing the need to delineate RNA, protein, and functional effects of each variant in order to accurately assign precision therapies. Genetic variants that impact pre-mRNA splicing are a common cause of genetic disease and have varying downstream molecular consequences. As a result, precision therapies that function at the protein level are not always effective for these variants and thus careful assessment is necessary. Here we evaluate RNA-level effects of 52 variants in the cystic fibrosis transmembrane conductance regulator (CFTR) gene and show that study of splicing and its consequences allows for more accurate assignment of precision therapies.
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Affiliation(s)
- Anya T. Joynt
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Taylor A. Evans
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Matthew J. Pellicore
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Emily F. Davis-Marcisak
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Melis A. Aksit
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Alice C. Eastman
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Shivani U. Patel
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins Hospital, Baltimore, Maryland, United States of America
| | - Kathleen C. Paul
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Derek L. Osorio
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Alyssa D. Bowling
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Calvin U. Cotton
- Departments of Pediatrics, Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Karen S. Raraigh
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Natalie E. West
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins Hospital, Baltimore, Maryland, United States of America
| | - Christian A. Merlo
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins Hospital, Baltimore, Maryland, United States of America
| | - Garry R. Cutting
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- * E-mail: (GRC); (NS)
| | - Neeraj Sharma
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- * E-mail: (GRC); (NS)
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46
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Abstract
PURPOSE OF REVIEW We describe and contrast the strengths of precision medicine with Western medicine, and complex trait genetics with Mendelian genetics. Classic genetics focuses on highly penetrant pathogenic variants in a single gene believed to cause or confer a high risk for well-defined phenotypes. However, a minority of disorders have a single gene cause. Further, even individuals with identical Mendelian disease-associated genotypes may exhibit substantial phenotypic variability indicative of genetic and environmental modifiers. Still, most diseases are considered complex traits (or complex diseases). RECENT FINDINGS New insights into the genetic underpinnings of complex traits provide opportunities for advances in diagnosis and management. Precision medicine provides the framework for integrating complex trait knowledge into clinical care through a sophisticated analysis pipeline. Multidimensional modeling of acquired diseases includes multiple genetic risks scattered over many genes and gene regulators that must be interpreted on the basis of functional evidence (e.g., genomics, transcriptomics) with structured models and expert systems; strengthened with machine learning and artificial intelligence. The choice of genotyping approaches (shotgun sequencing, single nucleotide polymorphism chips, targeted panels) is discussed. SUMMARY The result of a good precision medicine tool is clinical-decision support and guidance to tackle complex disorders such as pancreatitis, diabetes, and pancreatic cancer oncogenesis.
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47
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Alton EWFW, Boyd AC, Davies JC, Gill DR, Griesenbach U, Harman TE, Hyde S, McLachlan G. Gene Therapy for Respiratory Diseases: Progress and a Changing Context. Hum Gene Ther 2020; 31:911-916. [PMID: 32746737 DOI: 10.1089/hum.2020.142] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Affiliation(s)
- Eric W F W Alton
- Gene Therapy Group, National Heart and Lung Institute, Imperial College London, London, United Kingdom.,UK CF Gene Therapy Consortium, London, United Kingdom
| | - A Christopher Boyd
- UK CF Gene Therapy Consortium, London, United Kingdom.,Centre for Genomic and Experimental Medicine, IGMM, University of Edinburgh, Edinburgh, United Kingdom
| | - Jane C Davies
- Gene Therapy Group, National Heart and Lung Institute, Imperial College London, London, United Kingdom.,UK CF Gene Therapy Consortium, London, United Kingdom
| | - Deborah R Gill
- UK CF Gene Therapy Consortium, London, United Kingdom.,Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Uta Griesenbach
- Gene Therapy Group, National Heart and Lung Institute, Imperial College London, London, United Kingdom.,UK CF Gene Therapy Consortium, London, United Kingdom
| | - Tracy E Harman
- Gene Therapy Group, National Heart and Lung Institute, Imperial College London, London, United Kingdom.,UK CF Gene Therapy Consortium, London, United Kingdom
| | - Stephen Hyde
- UK CF Gene Therapy Consortium, London, United Kingdom.,Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Gerry McLachlan
- UK CF Gene Therapy Consortium, London, United Kingdom.,The Roslin Institute & R(D)SVS, Easter Bush Campus, University of Edinburgh, Edinburgh, United Kingdom
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48
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Laselva O, Bartlett C, Popa A, Ouyang H, Gunawardena TNA, Gonska T, Moraes TJ, Bear CE. Emerging preclinical modulators developed for F508del-CFTR have the potential to be effective for ORKAMBI resistant processing mutants. J Cyst Fibros 2020; 20:106-119. [PMID: 32741662 DOI: 10.1016/j.jcf.2020.07.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 07/07/2020] [Accepted: 07/22/2020] [Indexed: 10/23/2022]
Abstract
BACKGROUND F508del is prototypical of Class 2 CFTR mutations associated with protein misprocessing and reduced function. Corrector compounds like lumacaftor partially rescue the processing defect of F508del-CFTR whereas potentiators like ivacaftor, enhance its channel activity once trafficked to the cell surface. We asked if emerging modulators developed for F508del-CFTR can rescue Class 2 mutations previously shown to be poorly responsive to lumacaftor and ivacaftor. METHODS Rescue of mutant CFTRs by the correctors: AC1, AC2-1 or AC2-2 and the potentiator, AP2, was studied in HEK-293 cells and in primary human nasal epithelial (HNE) cultures, using a membrane potential assay and Ussing chamber, respectively. RESULTS In HEK-293 cells, we found that a particular combination of corrector molecules (AC1 plus AC2-1) and a potentiator (AP2) was effective in rescuing both the misprocessing and reduced function of M1101K and G85E respectively. These findings were recapitulated in patient-derived nasal cultures, although another corrector combination, AC1 plus AC2-2 also improved misprocessing in these primary tissues. Interestingly, while this corrector combination only led to a modest increase in the abundance of mature N1303K-CFTR it did enable its functional expression in the presence of the potentiator, AP2, in part, because the nominal corrector, AC2-2 also exhibits potentiator activity. CONCLUSIONS Strategic combinations of novel modulators can potentially rescue Class 2 mutants thought to be relatively unresponsive to lumacaftor and ivacaftor.
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Affiliation(s)
- Onofrio Laselva
- Programme in Molecular Medicine, Hospital for Sick Children, Toronto, Canada; Department of Physiology, University of Toronto, Toronto, Canada
| | - Claire Bartlett
- Programme in Translational Medicine, Hospital for Sick Children, Toronto, Canada
| | - Alec Popa
- Programme in Molecular Medicine, Hospital for Sick Children, Toronto, Canada
| | - Hong Ouyang
- Programme in Translational Medicine, Hospital for Sick Children, Toronto, Canada
| | | | - Tanja Gonska
- Programme in Translational Medicine, Hospital for Sick Children, Toronto, Canada; Department of Paediatrics, University of Toronto, Toronto, Canada
| | - Theo J Moraes
- Programme in Translational Medicine, Hospital for Sick Children, Toronto, Canada; Department of Paediatrics, University of Toronto, Toronto, Canada
| | - Christine E Bear
- Programme in Molecular Medicine, Hospital for Sick Children, Toronto, Canada; Department of Physiology, University of Toronto, Toronto, Canada; Department of Biochemistry, University of Toronto, Toronto, Canada.
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49
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Ubiquitination of disease-causing CFTR variants in a microsome-based assay. Anal Biochem 2020; 604:113829. [PMID: 32621804 DOI: 10.1016/j.ab.2020.113829] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 06/10/2020] [Accepted: 06/11/2020] [Indexed: 12/14/2022]
Abstract
Soluble secreted proteins and membrane proteins are subjected to protein quality control pathways during their synthesis in the endoplasmic reticulum (ER) and delivery to other destinations. Foremost among these quality control pathways is the selection of misfolded proteins for ER-associated degradation (ERAD). A growing number of diseases, including Cystic Fibrosis, are linked to the ERAD pathway. In most cases, a membrane protein known as the Cystic Fibrosis Transmembrane Conductance Regulator, or CFTR, is prematurely degraded by ERAD. Cell-based assays and in vitro studies have elucidated factors required for the recognition and degradation of CFTR, yet mechanistic details on how these factors target specific disease-causing variants is limited. Given the possibility that variants might exhibit unique susceptibilities to ubiquitin modification, which is required for proteasome-mediated degradation, we devised an assay that recapitulates this event. Here, we demonstrate that ER-enriched membranes from transfected human cells support CFTR ubiquitination when combined with radiolabeled ubiquitin and isolated enzymes in the ubiquitination cascade. We also show that select disease-causing variants are ubiquitinated more extensively than wild-type channels and to varying degrees. Our system provides a platform to examine how other purified factors impact CFTR ubiquitination and the ubiquitination of additional disease-associated membrane proteins.
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50
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Vece TJ, Wambach JA, Hagood JS. Childhood rare lung disease in the 21st century: "-omics" technology advances accelerating discovery. Pediatr Pulmonol 2020; 55:1828-1837. [PMID: 32533908 PMCID: PMC8711209 DOI: 10.1002/ppul.24809] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 04/28/2020] [Indexed: 01/14/2023]
Abstract
Childhood rare lung diseases comprise a large number of heterogeneous respiratory disorders that are individually rare but are collectively associated with substantial morbidity, mortality, and healthcare resource utilization. Although the genetic mechanisms for several of these disorders have been elucidated, the pathogenesis mechanisms for others remain poorly understood and treatment options remain limited. Childhood rare lung diseases are enriched for genetic etiologies; identification of the disease mechanisms underlying these rare disorders can inform the biology of normal human lung development and has implications for the treatment of more common respiratory diseases in children and adults. Advances in "-omics" technology, such as genomic sequencing, clinical phenotyping, biomarker discovery, genome editing, in vitro and model organism disease modeling, single-cell analyses, cellular imaging, and high-throughput drug screening have enabled significant progress for diagnosis and treatment of rare childhood lung diseases. The most striking example of this progress has been realized for patients with cystic fibrosis for whom effective, personalized therapies based on CFTR genotype are now available. In this chapter, we focus on recent technology advances in childhood rare lung diseases, acknowledge persistent challenges, and identify promising new technologies that will impact not only biological discovery, but also improve diagnosis, therapies, and survival for children with these rare disorders.
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Affiliation(s)
- Timothy J. Vece
- Division of Pediatric Pulmonology, Program for Rare and Interstitial Lung Disease, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Jennifer A. Wambach
- Division of Newborn Medicine, Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri
| | - James S. Hagood
- Division of Pediatric Pulmonology, Program for Rare and Interstitial Lung Disease, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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