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Sinha C, Zhang W, Moon CS, Actis M, Yarlagadda S, Arora K, Woodroofe K, Clancy JP, Lin S, Ziady AG, Frizzell R, Fujii N, Naren AP. Capturing the Direct Binding of CFTR Correctors to CFTR by Using Click Chemistry. Chembiochem 2015; 16:2017-22. [PMID: 26227551 DOI: 10.1002/cbic.201500123] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Indexed: 12/26/2022]
Abstract
Cystic fibrosis (CF) is a lethal genetic disease caused by the loss or dysfunction of the CF transmembrane conductance regulator (CFTR) channel. F508del is the most prevalent mutation of the CFTR gene and encodes a protein defective in folding and processing. VX-809 has been reported to facilitate the folding and trafficking of F508del-CFTR and augment its channel function. The mechanism of action of VX-809 has been poorly understood. In this study, we sought to answer a fundamental question underlying the mechanism of VX-809: does it bind CFTR directly in order to exert its action? We synthesized two VX-809 derivatives, ALK-809 and SUL-809, that possess an alkyne group and retain the rescue capacity of VX-809. By using Cu(I) -catalyzed click chemistry, we provide evidence that the VX-809 derivatives bind CFTR directly in vitro and in cells. Our findings will contribute to the elucidation of the mechanism of action of CFTR correctors and the design of more potent therapeutics to combat CF.
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Affiliation(s)
- Chandrima Sinha
- Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA.,Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, 38163, USA
| | - Weiqiang Zhang
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, 38163, USA.,Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN, 38103, USA
| | - Chang Suk Moon
- Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Marcelo Actis
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Sunitha Yarlagadda
- Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Kavisha Arora
- Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Koryse Woodroofe
- Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - John P Clancy
- Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Songbai Lin
- Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Assem G Ziady
- Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Raymond Frizzell
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15261, USA
| | - Naoaki Fujii
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Anjaparavanda P Naren
- Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA. .,Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, 38163, USA.
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202
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Phuan PW, Veit G, Tan JA, Finkbeiner WE, Lukacs GL, Verkman AS. Potentiators of Defective ΔF508-CFTR Gating that Do Not Interfere with Corrector Action. Mol Pharmacol 2015; 88:791-9. [PMID: 26245207 DOI: 10.1124/mol.115.099689] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Accepted: 08/04/2015] [Indexed: 02/04/2023] Open
Abstract
Combination drug therapies under development for cystic fibrosis caused by the ∆F508 mutation in cystic fibrosis transmembrane conductance regulator (CFTR) include a "corrector" to improve its cellular processing and a "potentiator" to improve its chloride channel function. Recently, it was reported that the approved potentiator N-(2,4-di-tert-butyl-5-hydroxyphenyl)-4-oxo-1,4-dihydroquinoline-3-carboxamide (Ivacaftor) reduces ∆F508-CFTR cellular stability and the efficacy of investigational correctors, including 3-(6-[([1-(2,2-difluoro-1,3-benzodioxol-5-yl)cyclopropyl]carbonyl) amino]-3-methyl-2-pyridinyl)-benzoic acid and 1-(2,2-difluoro-1,3-benzodioxol-5-yl)-N-(1-[(2R)-2,3-dihydroxypropyl]-6-fluoro-2-(2-hydroxy-1,1-dimethylethyl)-1H-indol-5-yl), which might contribute to the modest reported efficacy of combination therapy in clinical trials. Here, we report the identification and characterization of potentiators that do not interfere with ∆F508-CFTR stability or corrector action. High-throughput screening and structure-activity analysis identified several classes of potentiators that do not impair corrector action, including tetrahydrobenzothiophenes, thiooxoaminothiazoles, and pyrazole-pyrrole-isoxazoles. The most potent compounds have an EC(50) for ∆F508-CFTR potentiation down to 18 nM and do not reduce corrector efficacy in heterologous ∆F508-CFTR-expressing cells or primary cultures of ∆F508/∆F508 human bronchial epithelia. The ΔF508-CFTR potentiators also activated wild-type and G551D CFTR, albeit weakly. The efficacy of combination therapy for cystic fibrosis caused by the ∆F508 mutation may be improved by replacement of Ivacaftor with a potentiator that does not interfere with corrector action.
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Affiliation(s)
- Puay-Wah Phuan
- Departments of Medicine and Physiology (P.-W.P., J.A.T., A.S.V.) and Department of Pathology (W.E.F.), University of California, San Francisco, California; Department of Physiology and Groupe de Recherche Axé sur la Structure des Protéine (G.V., G.L.L.) and Department of Biochemistry (G.L.L.), McGill University, Montreal, Quebec, Canada
| | - Guido Veit
- Departments of Medicine and Physiology (P.-W.P., J.A.T., A.S.V.) and Department of Pathology (W.E.F.), University of California, San Francisco, California; Department of Physiology and Groupe de Recherche Axé sur la Structure des Protéine (G.V., G.L.L.) and Department of Biochemistry (G.L.L.), McGill University, Montreal, Quebec, Canada
| | - Joseph A Tan
- Departments of Medicine and Physiology (P.-W.P., J.A.T., A.S.V.) and Department of Pathology (W.E.F.), University of California, San Francisco, California; Department of Physiology and Groupe de Recherche Axé sur la Structure des Protéine (G.V., G.L.L.) and Department of Biochemistry (G.L.L.), McGill University, Montreal, Quebec, Canada
| | - Walter E Finkbeiner
- Departments of Medicine and Physiology (P.-W.P., J.A.T., A.S.V.) and Department of Pathology (W.E.F.), University of California, San Francisco, California; Department of Physiology and Groupe de Recherche Axé sur la Structure des Protéine (G.V., G.L.L.) and Department of Biochemistry (G.L.L.), McGill University, Montreal, Quebec, Canada
| | - Gergely L Lukacs
- Departments of Medicine and Physiology (P.-W.P., J.A.T., A.S.V.) and Department of Pathology (W.E.F.), University of California, San Francisco, California; Department of Physiology and Groupe de Recherche Axé sur la Structure des Protéine (G.V., G.L.L.) and Department of Biochemistry (G.L.L.), McGill University, Montreal, Quebec, Canada
| | - A S Verkman
- Departments of Medicine and Physiology (P.-W.P., J.A.T., A.S.V.) and Department of Pathology (W.E.F.), University of California, San Francisco, California; Department of Physiology and Groupe de Recherche Axé sur la Structure des Protéine (G.V., G.L.L.) and Department of Biochemistry (G.L.L.), McGill University, Montreal, Quebec, Canada
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203
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Bitam S, Pranke I, Hollenhorst M, Servel N, Moquereau C, Tondelier D, Hatton A, Urbach V, Sermet-Gaudelus I, Hinzpeter A, Edelman A. An unexpected effect of TNF-α on F508del-CFTR maturation and function. F1000Res 2015; 4:218. [PMID: 26594334 PMCID: PMC4648213 DOI: 10.12688/f1000research.6683.2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/28/2015] [Indexed: 01/12/2023] Open
Abstract
Cystic fibrosis (CF) is a multifactorial disease caused by mutations in the cystic fibrosis transmembrane conductance regulator gene ( CFTR), which encodes a cAMP-dependent Cl (-) channel. The most frequent mutation, F508del, leads to the synthesis of a prematurely degraded, otherwise partially functional protein. CFTR is expressed in many epithelia, with major consequences in the airways of patients with CF, characterized by both fluid transport abnormalities and persistent inflammatory responses. The relationship between the acute phase of inflammation and the expression of wild type (WT) CFTR or F508del-CFTR is poorly understood. The aim of the present study was to investigate this effect. The results show that 10 min exposure to TNF-alpha (0.5-50ng/ml) of F508del-CFTR-transfected HeLa cells and human bronchial cells expressing F508del-CFTR in primary culture (HBE) leads to the maturation of F508del-CFTR and induces CFTR chloride currents. The enhanced CFTR expression and function upon TNFα is sustained, in HBE cells, for at least 24 h. The underlying mechanism of action involves a protein kinase C (PKC) signaling pathway, and occurs through insertion of vesicles containing F508del-CFTR to the plasma membrane, with TNFα behaving as a corrector molecule. In conclusion, a novel and unexpected action of TNFα has been discovered and points to the importance of systematic studies on the roles of inflammatory mediators in the maturation of abnormally folded proteins in general and in the context of CF in particular.
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Affiliation(s)
- Sara Bitam
- Inserm U1151, Team 2 - CNRS UMR 8253, Faculté de Médecine Paris Descartes, Institut Necker Enfants Malades, Paris, 75993, France
| | - Iwona Pranke
- Inserm U1151, Team 2 - CNRS UMR 8253, Faculté de Médecine Paris Descartes, Institut Necker Enfants Malades, Paris, 75993, France
| | - Monika Hollenhorst
- Inserm U1151, Team 2 - CNRS UMR 8253, Faculté de Médecine Paris Descartes, Institut Necker Enfants Malades, Paris, 75993, France
| | - Nathalie Servel
- Inserm U1151, Team 2 - CNRS UMR 8253, Faculté de Médecine Paris Descartes, Institut Necker Enfants Malades, Paris, 75993, France
| | - Christelle Moquereau
- Inserm U1151, Team 2 - CNRS UMR 8253, Faculté de Médecine Paris Descartes, Institut Necker Enfants Malades, Paris, 75993, France
| | - Danielle Tondelier
- Inserm U1151, Team 2 - CNRS UMR 8253, Faculté de Médecine Paris Descartes, Institut Necker Enfants Malades, Paris, 75993, France
| | - Aurélie Hatton
- Inserm U1151, Team 2 - CNRS UMR 8253, Faculté de Médecine Paris Descartes, Institut Necker Enfants Malades, Paris, 75993, France
| | - Valérie Urbach
- Inserm U1151, Team 2 - CNRS UMR 8253, Faculté de Médecine Paris Descartes, Institut Necker Enfants Malades, Paris, 75993, France
| | - Isabelle Sermet-Gaudelus
- Inserm U1151, Team 2 - CNRS UMR 8253, Faculté de Médecine Paris Descartes, Institut Necker Enfants Malades, Paris, 75993, France
| | - Alexandre Hinzpeter
- INSERM U955, Team 5, Université Paris Est Créteil, Champs-sur-Marne, 77420, France
| | - Aleksander Edelman
- Inserm U1151, Team 2 - CNRS UMR 8253, Faculté de Médecine Paris Descartes, Institut Necker Enfants Malades, Paris, 75993, France
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204
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Londino JD, Lazrak A, Noah JW, Aggarwal S, Bali V, Woodworth BA, Bebok Z, Matalon S. Influenza virus M2 targets cystic fibrosis transmembrane conductance regulator for lysosomal degradation during viral infection. FASEB J 2015; 29:2712-25. [PMID: 25795456 PMCID: PMC4478808 DOI: 10.1096/fj.14-268755] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 02/26/2015] [Indexed: 12/24/2022]
Abstract
We sought to determine the mechanisms by which influenza infection of human epithelial cells decreases cystic fibrosis transmembrane conductance regulator (CFTR) expression and function. We infected human bronchial epithelial (NHBE) cells and murine nasal epithelial (MNE) cells with various strains of influenza A virus. Influenza infection significantly reduced CFTR short circuit currents (Isc) and protein levels at 8 hours postinfection. We then infected CFTR expressing human embryonic kidney (HEK)-293 cells (HEK-293 CFTRwt) with influenza virus encoding a green fluorescent protein (GFP) tag and performed whole-cell and cell-attached patch clamp recordings. Forskolin-stimulated, GlyH-101-sensitive CFTR conductances, and CFTR open probabilities were reduced by 80% in GFP-positive cells; Western blots also showed significant reduction in total and plasma membrane CFTR levels. Knockdown of the influenza matrix protein 2 (M2) with siRNA, or inhibition of its activity by amantadine, prevented the decrease in CFTR expression and function. Lysosome inhibition (bafilomycin-A1), but not proteasome inhibition (lactacystin), prevented the reduction in CFTR levels. Western blots of immunoprecipitated CFTR from influenza-infected cells, treated with BafA1, and probed with antibodies against lysine 63-linked (K-63) or lysine 48-linked (K-48) polyubiquitin chains supported lysosomal targeting. These results highlight CFTR damage, leading to early degradation as an important contributing factor to influenza infection-associated ion transport defects.
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Affiliation(s)
- James David Londino
- *Department of Anesthesiology, Pulmonary Injury and Repair Center, and Department of Cell, Developmental and Integrative Biology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA; Southern Research Institute, Birmingham, Alabama, USA; and Department of Surgery, Division of Otolaryngology, School of Medicine, University of Alabama, Birmingham, Alabama, USA
| | - Ahmed Lazrak
- *Department of Anesthesiology, Pulmonary Injury and Repair Center, and Department of Cell, Developmental and Integrative Biology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA; Southern Research Institute, Birmingham, Alabama, USA; and Department of Surgery, Division of Otolaryngology, School of Medicine, University of Alabama, Birmingham, Alabama, USA
| | - James W Noah
- *Department of Anesthesiology, Pulmonary Injury and Repair Center, and Department of Cell, Developmental and Integrative Biology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA; Southern Research Institute, Birmingham, Alabama, USA; and Department of Surgery, Division of Otolaryngology, School of Medicine, University of Alabama, Birmingham, Alabama, USA
| | - Saurabh Aggarwal
- *Department of Anesthesiology, Pulmonary Injury and Repair Center, and Department of Cell, Developmental and Integrative Biology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA; Southern Research Institute, Birmingham, Alabama, USA; and Department of Surgery, Division of Otolaryngology, School of Medicine, University of Alabama, Birmingham, Alabama, USA
| | - Vedrana Bali
- *Department of Anesthesiology, Pulmonary Injury and Repair Center, and Department of Cell, Developmental and Integrative Biology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA; Southern Research Institute, Birmingham, Alabama, USA; and Department of Surgery, Division of Otolaryngology, School of Medicine, University of Alabama, Birmingham, Alabama, USA
| | - Bradford A Woodworth
- *Department of Anesthesiology, Pulmonary Injury and Repair Center, and Department of Cell, Developmental and Integrative Biology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA; Southern Research Institute, Birmingham, Alabama, USA; and Department of Surgery, Division of Otolaryngology, School of Medicine, University of Alabama, Birmingham, Alabama, USA
| | - Zsuzsanna Bebok
- *Department of Anesthesiology, Pulmonary Injury and Repair Center, and Department of Cell, Developmental and Integrative Biology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA; Southern Research Institute, Birmingham, Alabama, USA; and Department of Surgery, Division of Otolaryngology, School of Medicine, University of Alabama, Birmingham, Alabama, USA
| | - Sadis Matalon
- *Department of Anesthesiology, Pulmonary Injury and Repair Center, and Department of Cell, Developmental and Integrative Biology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA; Southern Research Institute, Birmingham, Alabama, USA; and Department of Surgery, Division of Otolaryngology, School of Medicine, University of Alabama, Birmingham, Alabama, USA
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205
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Dekker SL, Kampinga HH, Bergink S. DNAJs: more than substrate delivery to HSPA. Front Mol Biosci 2015; 2:35. [PMID: 26176011 PMCID: PMC4485348 DOI: 10.3389/fmolb.2015.00035] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 06/12/2015] [Indexed: 11/20/2022] Open
Abstract
Proteins are essential components of cellular life, as building blocks, but also to guide and execute all cellular processes. Proteins require a three-dimensional folding, which is constantly being challenged by their environment. Challenges including elevated temperatures or redox changes can alter this fold and result in misfolding of proteins or even aggregation. Cells are equipped with several pathways that can deal with protein stress. Together, these pathways are referred to as the protein quality control network. The network comprises degradation and (re)folding pathways that are intertwined due to the sharing of components and by the overlap in affinity for substrates. Here, we will give examples of this sharing and intertwinement of protein degradation and protein folding and discuss how the fate of a substrate is determined. We will focus on the ubiquitylation of substrates and the role of Hsp70 co-chaperones of the DNAJ class in this process.
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Affiliation(s)
- Suzanne L Dekker
- Department of Cell Biology, University Medical Center Groningen, University of Groningen Groningen, Netherlands
| | - Harm H Kampinga
- Department of Cell Biology, University Medical Center Groningen, University of Groningen Groningen, Netherlands
| | - Steven Bergink
- Department of Cell Biology, University Medical Center Groningen, University of Groningen Groningen, Netherlands
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206
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Mall MA, Galietta LJV. Targeting ion channels in cystic fibrosis. J Cyst Fibros 2015; 14:561-70. [PMID: 26115565 DOI: 10.1016/j.jcf.2015.06.002] [Citation(s) in RCA: 117] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 05/28/2015] [Accepted: 06/01/2015] [Indexed: 12/12/2022]
Abstract
Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene cause a characteristic defect in epithelial ion transport that plays a central role in the pathogenesis of cystic fibrosis (CF). Hence, pharmacological correction of this ion transport defect by targeting of mutant CFTR, or alternative ion channels that may compensate for CFTR dysfunction, has long been considered as an attractive approach to a causal therapy of this life-limiting disease. The recent introduction of the CFTR potentiator ivacaftor into the therapy of a subgroup of patients with specific CFTR mutations was a major milestone and enormous stimulus for seeking effective ion transport modulators for all patients with CF. In this review, we discuss recent breakthroughs and setbacks with CFTR modulators designed to rescue mutant CFTR including the common mutation F508del. Further, we examine the alternative chloride channels TMEM16A and SLC26A9, as well as the epithelial sodium channel ENaC as alternative targets in CF lung disease, which remains the major cause of morbidity and mortality in patients with CF. Finally, we will focus on the hurdles that still need to be overcome to make effective ion transport modulation therapies available for all patients with CF irrespective of their CFTR genotype.
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Affiliation(s)
- Marcus A Mall
- Department of Translational Pulmonology, Translational Lung Research Center Heidelberg (TLRC), Member of the German Center for Lung Research (DZL), University of Heidelberg, Heidelberg, Germany; Division of Pediatric Pulmonology & Allergy and Cystic Fibrosis Center, Department of Pediatrics, University of Heidelberg, Heidelberg, Germany.
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207
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Maiuri L, De Stefano D, Raia V, Kroemer G. The holy grail of cystic fibrosis research: pharmacological repair of the F508del-CFTR mutation. ANNALS OF TRANSLATIONAL MEDICINE 2015; 3:S24. [PMID: 26046070 DOI: 10.3978/j.issn.2305-5839.2015.02.32] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 02/10/2015] [Indexed: 11/14/2022]
Affiliation(s)
- Luigi Maiuri
- 1 European Institute for Research in Cystic Fibrosis, San Raffaele Scientific Institute, Milan, Italy ; 2 SCDU of Pediatrics, Department of Health Sciences, University of Piemonte Orientale, Novara, Italy ; 3 Regional Cystic Fibrosis Center; Pediatric Unit, Department of Translational Medical Sciences, Federico II University, Naples, Italy ; 4 Equipe 11 labellisee Ligue contre le Cancer; INSERM U1138; Centre de Recherche des Cordeliers, Paris, France ; 5 Universite Paris Descartes, Paris, France ; 6 Metabolomics and Cell Biology Platforms, Institut Gustave Roussy, Villejuif, France ; 7 Pole de Biologie, Hopital Européen Georges Pompidou, AP-HP, Paris, France
| | - Daniela De Stefano
- 1 European Institute for Research in Cystic Fibrosis, San Raffaele Scientific Institute, Milan, Italy ; 2 SCDU of Pediatrics, Department of Health Sciences, University of Piemonte Orientale, Novara, Italy ; 3 Regional Cystic Fibrosis Center; Pediatric Unit, Department of Translational Medical Sciences, Federico II University, Naples, Italy ; 4 Equipe 11 labellisee Ligue contre le Cancer; INSERM U1138; Centre de Recherche des Cordeliers, Paris, France ; 5 Universite Paris Descartes, Paris, France ; 6 Metabolomics and Cell Biology Platforms, Institut Gustave Roussy, Villejuif, France ; 7 Pole de Biologie, Hopital Européen Georges Pompidou, AP-HP, Paris, France
| | - Valeria Raia
- 1 European Institute for Research in Cystic Fibrosis, San Raffaele Scientific Institute, Milan, Italy ; 2 SCDU of Pediatrics, Department of Health Sciences, University of Piemonte Orientale, Novara, Italy ; 3 Regional Cystic Fibrosis Center; Pediatric Unit, Department of Translational Medical Sciences, Federico II University, Naples, Italy ; 4 Equipe 11 labellisee Ligue contre le Cancer; INSERM U1138; Centre de Recherche des Cordeliers, Paris, France ; 5 Universite Paris Descartes, Paris, France ; 6 Metabolomics and Cell Biology Platforms, Institut Gustave Roussy, Villejuif, France ; 7 Pole de Biologie, Hopital Européen Georges Pompidou, AP-HP, Paris, France
| | - Guido Kroemer
- 1 European Institute for Research in Cystic Fibrosis, San Raffaele Scientific Institute, Milan, Italy ; 2 SCDU of Pediatrics, Department of Health Sciences, University of Piemonte Orientale, Novara, Italy ; 3 Regional Cystic Fibrosis Center; Pediatric Unit, Department of Translational Medical Sciences, Federico II University, Naples, Italy ; 4 Equipe 11 labellisee Ligue contre le Cancer; INSERM U1138; Centre de Recherche des Cordeliers, Paris, France ; 5 Universite Paris Descartes, Paris, France ; 6 Metabolomics and Cell Biology Platforms, Institut Gustave Roussy, Villejuif, France ; 7 Pole de Biologie, Hopital Européen Georges Pompidou, AP-HP, Paris, France
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Loureiro CA, Matos AM, Dias-Alves Â, Pereira JF, Uliyakina I, Barros P, Amaral MD, Matos P. A molecular switch in the scaffold NHERF1 enables misfolded CFTR to evade the peripheral quality control checkpoint. Sci Signal 2015; 8:ra48. [PMID: 25990958 DOI: 10.1126/scisignal.aaa1580] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The peripheral protein quality control (PPQC) checkpoint removes improperly folded proteins from the plasma membrane through a mechanism involving the E3 ubiquitin ligase CHIP (carboxyl terminus of Hsc70 interacting protein). PPQC limits the efficacy of some cystic fibrosis (CF) drugs, such as VX-809, that improve trafficking to the plasma membrane of misfolded mutants of the CF transmembrane conductance regulator (CFTR), including F508del-CFTR, which retains partial functionality. We investigated the PPQC checkpoint in lung epithelial cells with F508del-CFTR that were exposed to VX-809. The conformation of the scaffold protein NHERF1 (Na(+)/H(+) exchange regulatory factor 1) determined whether the PPQC recognized "rescued" F508del-CFTR (the portion that reached the cell surface in VX-809-treated cells). Activation of the cytoskeletal regulator Rac1 promoted an interaction between the actin-binding adaptor protein ezrin and NHERF1, triggering exposure of the second PDZ domain of NHERF1, which interacted with rescued F508del-CFTR. Because binding of F508del-CFTR to the second PDZ of NHERF1 precluded the recruitment of CHIP, the coexposure of airway cells to Rac1 activator nearly tripled the efficacy of VX-809. Interference with the NHERF1-ezrin interaction prevented the increase of efficacy of VX-809 by Rac1 activation, but the actin-binding domain of ezrin was not required for the increase in efficacy. Thus, rather than mainly directing anchoring of F508del-CFTR to the actin cytoskeleton, induction of ezrin activation by Rac1 signaling triggered a conformational change in NHERF1, which was then able to bind and stabilize misfolded CFTR at the plasma membrane. These insights into the cell surface stabilization of CFTR provide new targets to improve treatment of CF.
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Affiliation(s)
- Cláudia A Loureiro
- Department of Human Genetics, National Health Institute Doutor Ricardo Jorge, Av. Padre Cruz, 1649-016 Lisboa, Portugal. Biosystems & Integrative Sciences Institute (BioISI), Faculty of Sciences, University of Lisboa, Campo Grande-C8, 1749-016 Lisboa, Portugal
| | - Ana Margarida Matos
- Department of Human Genetics, National Health Institute Doutor Ricardo Jorge, Av. Padre Cruz, 1649-016 Lisboa, Portugal. Biosystems & Integrative Sciences Institute (BioISI), Faculty of Sciences, University of Lisboa, Campo Grande-C8, 1749-016 Lisboa, Portugal
| | - Ângela Dias-Alves
- Department of Human Genetics, National Health Institute Doutor Ricardo Jorge, Av. Padre Cruz, 1649-016 Lisboa, Portugal. Biosystems & Integrative Sciences Institute (BioISI), Faculty of Sciences, University of Lisboa, Campo Grande-C8, 1749-016 Lisboa, Portugal
| | - Joana F Pereira
- Department of Human Genetics, National Health Institute Doutor Ricardo Jorge, Av. Padre Cruz, 1649-016 Lisboa, Portugal. Biosystems & Integrative Sciences Institute (BioISI), Faculty of Sciences, University of Lisboa, Campo Grande-C8, 1749-016 Lisboa, Portugal
| | - Inna Uliyakina
- Biosystems & Integrative Sciences Institute (BioISI), Faculty of Sciences, University of Lisboa, Campo Grande-C8, 1749-016 Lisboa, Portugal
| | - Patrícia Barros
- Department of Human Genetics, National Health Institute Doutor Ricardo Jorge, Av. Padre Cruz, 1649-016 Lisboa, Portugal. Biosystems & Integrative Sciences Institute (BioISI), Faculty of Sciences, University of Lisboa, Campo Grande-C8, 1749-016 Lisboa, Portugal
| | - Margarida D Amaral
- Biosystems & Integrative Sciences Institute (BioISI), Faculty of Sciences, University of Lisboa, Campo Grande-C8, 1749-016 Lisboa, Portugal
| | - Paulo Matos
- Department of Human Genetics, National Health Institute Doutor Ricardo Jorge, Av. Padre Cruz, 1649-016 Lisboa, Portugal. Biosystems & Integrative Sciences Institute (BioISI), Faculty of Sciences, University of Lisboa, Campo Grande-C8, 1749-016 Lisboa, Portugal.
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Abstract
Cystic fibrosis is an autosomal recessive, monogenetic disorder caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The gene defect was first described 25 years ago and much progress has been made since then in our understanding of how CFTR mutations cause disease and how this can be addressed therapeutically. CFTR is a transmembrane protein that transports ions across the surface of epithelial cells. CFTR dysfunction affects many organs; however, lung disease is responsible for the vast majority of morbidity and mortality in patients with cystic fibrosis. Prenatal diagnostics, newborn screening and new treatment algorithms are changing the incidence and the prevalence of the disease. Until recently, the standard of care in cystic fibrosis treatment focused on preventing and treating complications of the disease; now, novel treatment strategies directly targeting the ion channel abnormality are becoming available and it will be important to evaluate how these treatments affect disease progression and the quality of life of patients. In this Primer, we summarize the current knowledge, and provide an outlook on how cystic fibrosis clinical care and research will be affected by new knowledge and therapeutic options in the near future. For an illustrated summary of this Primer, visit: http://go.nature.com/4VrefN.
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Fu L, Rab A, Tang LP, Bebok Z, Rowe SM, Bartoszewski R, Collawn JF. ΔF508 CFTR surface stability is regulated by DAB2 and CHIP-mediated ubiquitination in post-endocytic compartments. PLoS One 2015; 10:e0123131. [PMID: 25879443 PMCID: PMC4399842 DOI: 10.1371/journal.pone.0123131] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 02/16/2015] [Indexed: 01/05/2023] Open
Abstract
The ΔF508 mutant form of the cystic fibrosis transmembrane conductance regulator (ΔF508 CFTR) that is normally degraded by the ER-associated degradative pathway can be rescued to the cell surface through low-temperature (27°C) culture or small molecular corrector treatment. However, it is unstable on the cell surface, and rapidly internalized and targeted to the lysosomal compartment for degradation. To understand the mechanism of this rapid turnover, we examined the role of two adaptor complexes (AP-2 and Dab2) and three E3 ubiquitin ligases (c-Cbl, CHIP, and Nedd4-2) on low-temperature rescued ΔF508 CFTR endocytosis and degradation in human airway epithelial cells. Our results demonstrate that siRNA depletion of either AP-2 or Dab2 inhibits ΔF508 CFTR endocytosis by 69% and 83%, respectively. AP-2 or Dab2 depletion also increases the rescued protein half-life of ΔF508 CFTR by ~18% and ~91%, respectively. In contrast, the depletion of each of the E3 ligases had no effect on ΔF508 CFTR endocytosis, whereas CHIP depletion significantly increased the surface half-life of ΔF508 CFTR. To determine where and when the ubiquitination occurs during ΔF508 CFTR turnover, we monitored the ubiquitination of rescued ΔF508 CFTR during the time course of CFTR endocytosis. Our results indicate that ubiquitination of the surface pool of ΔF508 CFTR begins to increase 15 min after internalization, suggesting that CFTR is ubiquitinated in a post-endocytic compartment. This post-endocytic ubiquination of ΔF508 CFTR could be blocked by either inhibiting endocytosis, by siRNA knockdown of CHIP, or by treating cells with the CFTR corrector, VX-809. Our results indicate that the post-endocytic ubiquitination of CFTR by CHIP is a critical step in the peripheral quality control of cell surface ΔF508 CFTR.
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Affiliation(s)
- Lianwu Fu
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
- * E-mail: (LF); (JFC)
| | - Andras Rab
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Li ping Tang
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Zsuzsa Bebok
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Steven M. Rowe
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Rafal Bartoszewski
- Department of Biology and Pharmaceutical Botany, Medical University of Gdansk, Gdansk, Poland
| | - James F. Collawn
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
- * E-mail: (LF); (JFC)
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211
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Abstract
The plasma membrane (PM) and endocytic protein quality control (QC) in conjunction with the endosomal sorting machinery either repairs or targets conformationally damaged membrane proteins for lysosomal/vacuolar degradation. Here, we provide an overview of emerging aspects of the underlying mechanisms of PM QC that fulfill a critical role in preserving cellular protein homeostasis in health and diseases.
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Affiliation(s)
- Pirjo M Apaja
- Department of Physiology and Research Group Focused on Protein Structure (GRASP), McGill University, Montreal, Quebec, Canada; and
| | - Gergely L Lukacs
- Department of Physiology and Research Group Focused on Protein Structure (GRASP), McGill University, Montreal, Quebec, Canada; and Department of Biochemistry, McGill University, Montreal, Quebec, Canada
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212
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Cholon DM, Quinney NL, Fulcher ML, Esther CR, Das J, Dokholyan NV, Randell SH, Boucher RC, Gentzsch M. Potentiator ivacaftor abrogates pharmacological correction of ΔF508 CFTR in cystic fibrosis. Sci Transl Med 2015; 6:246ra96. [PMID: 25101886 DOI: 10.1126/scitranslmed.3008680] [Citation(s) in RCA: 261] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cystic fibrosis (CF) is caused by mutations in the CF transmembrane conductance regulator (CFTR). Newly developed "correctors" such as lumacaftor (VX-809) that improve CFTR maturation and trafficking and "potentiators" such as ivacaftor (VX-770) that enhance channel activity may provide important advances in CF therapy. Although VX-770 has demonstrated substantial clinical efficacy in the small subset of patients with a mutation (G551D) that affects only channel activity, a single compound is not sufficient to treat patients with the more common CFTR mutation, ΔF508. Thus, patients with ΔF508 will likely require treatment with both correctors and potentiators to achieve clinical benefit. However, whereas the effectiveness of acute treatment with this drug combination has been demonstrated in vitro, the impact of chronic therapy has not been established. In studies of human primary airway epithelial cells, we found that both acute and chronic treatment with VX-770 improved CFTR function in cells with the G551D mutation, consistent with clinical studies. In contrast, chronic VX-770 administration caused a dose-dependent reversal of VX-809-mediated CFTR correction in ΔF508 homozygous cultures. This result reflected the destabilization of corrected ΔF508 CFTR by VX-770, markedly increasing its turnover rate. Chronic VX-770 treatment also reduced mature wild-type CFTR levels and function. These findings demonstrate that chronic treatment with CFTR potentiators and correctors may have unexpected effects that cannot be predicted from short-term studies. Combining these drugs to maximize rescue of ΔF508 CFTR may require changes in dosing and/or development of new potentiator compounds that do not interfere with CFTR stability.
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Affiliation(s)
- Deborah M Cholon
- Marsico Lung Institute/Cystic Fibrosis Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Nancy L Quinney
- Marsico Lung Institute/Cystic Fibrosis Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - M Leslie Fulcher
- Marsico Lung Institute/Cystic Fibrosis Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Charles R Esther
- Marsico Lung Institute/Cystic Fibrosis Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. Division of Pediatric Pulmonology, Department of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jhuma Das
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Nikolay V Dokholyan
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Scott H Randell
- Marsico Lung Institute/Cystic Fibrosis Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Richard C Boucher
- Marsico Lung Institute/Cystic Fibrosis Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Martina Gentzsch
- Marsico Lung Institute/Cystic Fibrosis Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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213
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Veit G, Avramescu RG, Perdomo D, Phuan PW, Bagdany M, Apaja PM, Borot F, Szollosi D, Wu YS, Finkbeiner WE, Hegedus T, Verkman AS, Lukacs GL. Some gating potentiators, including VX-770, diminish ΔF508-CFTR functional expression. Sci Transl Med 2015; 6:246ra97. [PMID: 25101887 DOI: 10.1126/scitranslmed.3008889] [Citation(s) in RCA: 250] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Cystic fibrosis (CF) is caused by mutations in the CF transmembrane regulator (CFTR) that result in reduced anion conductance at the apical membrane of secretory epithelia. Treatment of CF patients carrying the G551D gating mutation with the potentiator VX-770 (ivacaftor) largely restores channel activity and has shown substantial clinical benefit. However, most CF patients carry the ΔF508 mutation, which impairs CFTR folding, processing, function, and stability. Studies in homozygous ΔF508 CF patients indicated little clinical benefit of monotherapy with the investigational corrector VX-809 (lumacaftor) or VX-770, whereas combination clinical trials show limited but significant improvements in lung function. We show that VX-770, as well as most other potentiators, reduces the correction efficacy of VX-809 and another investigational corrector, VX-661. To mimic the administration of VX-770 alone or in combination with VX-809, we examined its long-term effect in immortalized and primary human respiratory epithelia. VX-770 diminished the folding efficiency and the metabolic stability of ΔF508-CFTR at the endoplasmic reticulum (ER) and post-ER compartments, respectively, causing reduced cell surface ΔF508-CFTR density and function. VX-770-induced destabilization of ΔF508-CFTR was influenced by second-site suppressor mutations of the folding defect and was prevented by stabilization of the nucleotide-binding domain 1 (NBD1)-NBD2 interface. The reduced correction efficiency of ΔF508-CFTR, as well as of two other processing mutations in the presence of VX-770, suggests the need for further optimization of potentiators to maximize the clinical benefit of corrector-potentiator combination therapy in CF.
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Affiliation(s)
- Guido Veit
- Department of Physiology, McGill University, Montréal, Quebec H3G 1Y6, Canada
| | - Radu G Avramescu
- Department of Physiology, McGill University, Montréal, Quebec H3G 1Y6, Canada
| | - Doranda Perdomo
- Department of Physiology, McGill University, Montréal, Quebec H3G 1Y6, Canada
| | - Puay-Wah Phuan
- Departments of Medicine and Physiology, University of California, San Francisco, San Francisco, CA 94143-0521, USA
| | - Miklos Bagdany
- Department of Physiology, McGill University, Montréal, Quebec H3G 1Y6, Canada
| | - Pirjo M Apaja
- Department of Physiology, McGill University, Montréal, Quebec H3G 1Y6, Canada
| | - Florence Borot
- Department of Physiology, McGill University, Montréal, Quebec H3G 1Y6, Canada
| | - Daniel Szollosi
- MTA-SE Molecular Biophysics Research Group, Hungarian Academy of Sciences, 1444 Budapest, Hungary. Department of Biophysics and Radiation Biology, Semmelweis University, 1444 Budapest P.O. Box 263, Hungary
| | - Yu-Sheng Wu
- Department of Physiology, McGill University, Montréal, Quebec H3G 1Y6, Canada
| | - Walter E Finkbeiner
- Department of Pathology, University of California, San Francisco, San Francisco, CA 94143-0511, USA
| | - Tamas Hegedus
- MTA-SE Molecular Biophysics Research Group, Hungarian Academy of Sciences, 1444 Budapest, Hungary. Department of Biophysics and Radiation Biology, Semmelweis University, 1444 Budapest P.O. Box 263, Hungary
| | - Alan S Verkman
- Departments of Medicine and Physiology, University of California, San Francisco, San Francisco, CA 94143-0521, USA
| | - Gergely L Lukacs
- Department of Physiology, McGill University, Montréal, Quebec H3G 1Y6, Canada. Department of Biochemistry, McGill University, Montréal, Quebec H3G 1Y6, Canada. Groupe de Recherche Axé sur la Structure des Protéines (GRASP), McGill University, Montréal, Quebec H3G 1Y6, Canada.
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214
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Trzcińska-Daneluti AM, Chen A, Nguyen L, Murchie R, Jiang C, Moffat J, Pelletier L, Rotin D. RNA Interference Screen to Identify Kinases That Suppress Rescue of ΔF508-CFTR. Mol Cell Proteomics 2015; 14:1569-83. [PMID: 25825526 DOI: 10.1074/mcp.m114.046375] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Indexed: 01/08/2023] Open
Abstract
Cystic Fibrosis (CF) is an autosomal recessive disorder caused by mutations in the gene encoding the Cystic fibrosis transmembrane conductance regulator (CFTR). ΔF508-CFTR, the most common disease-causing CF mutant, exhibits folding and trafficking defects and is retained in the endoplasmic reticulum, where it is targeted for proteasomal degradation. To identify signaling pathways involved in ΔF508-CFTR rescue, we screened a library of endoribonuclease-prepared short interfering RNAs (esiRNAs) that target ∼750 different kinases and associated signaling proteins. We identified 20 novel suppressors of ΔF508-CFTR maturation, including the FGFR1. These were subsequently validated by measuring channel activity by the YFP halide-sensitive assay following shRNA-mediated knockdown, immunoblotting for the mature (band C) ΔF508-CFTR and measuring the amount of surface ΔF508-CFTR by ELISA. The role of FGFR signaling on ΔF508-CFTR trafficking was further elucidated by knocking down FGFRs and their downstream signaling proteins: Erk1/2, Akt, PLCγ-1, and FRS2. Interestingly, inhibition of FGFR1 with SU5402 administered to intestinal organoids (mini-guts) generated from the ileum of ΔF508-CFTR homozygous mice resulted in a robust ΔF508-CFTR rescue. Moreover, combination of SU5402 and VX-809 treatments in cells led to an additive enhancement of ΔF508-CFTR rescue, suggesting these compounds operate by different mechanisms. Chaperone array analysis on human bronchial epithelial cells harvested from ΔF508/ΔF508-CFTR transplant patients treated with SU5402 identified altered expression of several chaperones, an effect validated by their overexpression or knockdown experiments. We propose that FGFR signaling regulates specific chaperones that control ΔF508-CFTR maturation, and suggest that FGFRs may serve as important targets for therapeutic intervention for the treatment of CF.
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Affiliation(s)
- Agata M Trzcińska-Daneluti
- From the ‡Program in Cell Biology, The Hospital for Sick Children, Toronto, and Biochemistry Department, University of Toronto; PGCRL, 19-9715, 686 Bay St., Toronto, Ont., Canada, M5G 0A4
| | - Anthony Chen
- From the ‡Program in Cell Biology, The Hospital for Sick Children, Toronto, and Biochemistry Department, University of Toronto; PGCRL, 19-9715, 686 Bay St., Toronto, Ont., Canada, M5G 0A4
| | - Leo Nguyen
- From the ‡Program in Cell Biology, The Hospital for Sick Children, Toronto, and Biochemistry Department, University of Toronto; PGCRL, 19-9715, 686 Bay St., Toronto, Ont., Canada, M5G 0A4
| | - Ryan Murchie
- From the ‡Program in Cell Biology, The Hospital for Sick Children, Toronto, and Biochemistry Department, University of Toronto; PGCRL, 19-9715, 686 Bay St., Toronto, Ont., Canada, M5G 0A4
| | - Chong Jiang
- From the ‡Program in Cell Biology, The Hospital for Sick Children, Toronto, and Biochemistry Department, University of Toronto; PGCRL, 19-9715, 686 Bay St., Toronto, Ont., Canada, M5G 0A4
| | | | | | - Daniela Rotin
- From the ‡Program in Cell Biology, The Hospital for Sick Children, Toronto, and Biochemistry Department, University of Toronto; PGCRL, 19-9715, 686 Bay St., Toronto, Ont., Canada, M5G 0A4
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215
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Involvement of the Cdc42 pathway in CFTR post-translational turnover and in its plasma membrane stability in airway epithelial cells. PLoS One 2015; 10:e0118943. [PMID: 25768293 PMCID: PMC4359135 DOI: 10.1371/journal.pone.0118943] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 01/07/2015] [Indexed: 12/21/2022] Open
Abstract
Cystic fibrosis transmembrane conductance regulator (CFTR) is a chloride channel that is expressed on the apical plasma membrane (PM) of epithelial cells. The most common deleterious allele encodes a trafficking-defective mutant protein undergoing endoplasmic reticulum-associated degradation (ERAD) and presenting lower PM stability. In this study, we investigated the involvement of the Cdc42 pathway in CFTR turnover and trafficking in a human bronchiolar epithelial cell line (CFBE41o-) expressing wild-type CFTR. Cdc42 is a small GTPase of the Rho family that fulfils numerous cell functions, one of which is endocytosis and recycling process via actin cytoskeleton remodelling. When we treated cells with chemical inhibitors such as ML141 against Cdc42 and wiskostatin against the downstream effector N-WASP, we observed that CFTR channel activity was inhibited, in correlation with a decrease in CFTR amount at the cell surface and an increase in dynamin-dependent CFTR endocytosis. Anchoring of CFTR to the cortical cytoskeleton was then presumably impaired by actin disorganization. When we performed siRNA-mediated depletion of Cdc42, actin polymerization was not impacted, but we observed actin-independent consequences upon CFTR. Total and PM CFTR amounts were increased, resulting in greater activation of CFTR. Pulse-chase experiments showed that while CFTR degradation was slowed, CFTR maturation through the Golgi apparatus remained unaffected. In addition, we observed increased stability of CFTR in PM and reduction of its endocytosis. This study highlights the involvement of the Cdc42 pathway at several levels of CFTR biogenesis and trafficking: (i) Cdc42 is implicated in the first steps of CFTR biosynthesis and processing; (ii) it contributes to the stability of CFTR in PM via its anchoring to cortical actin; (iii) it promotes CFTR endocytosis and presumably its sorting toward lysosomal degradation.
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216
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Satpute-Krishnan P, Ajinkya M, Bhat S, Itakura E, Hegde RS, Lippincott-Schwartz J. ER stress-induced clearance of misfolded GPI-anchored proteins via the secretory pathway. Cell 2015; 158:522-33. [PMID: 25083867 PMCID: PMC4121523 DOI: 10.1016/j.cell.2014.06.026] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2013] [Revised: 04/08/2014] [Accepted: 06/09/2014] [Indexed: 11/15/2022]
Abstract
Proteins destined for the cell surface are first assessed in the endoplasmic reticulum (ER) for proper folding before release into the secretory pathway. This ensures that defective proteins are normally prevented from entering the extracellular environment, where they could be disruptive. Here, we report that, when ER folding capacity is saturated during stress, misfolded glycosylphosphatidylinositol-anchored proteins dissociate from resident ER chaperones, engage export receptors, and quantitatively leave the ER via vesicular transport to the Golgi. Clearance from the ER commences within minutes of acute ER stress, before the transcriptional component of the unfolded protein response is activated. These aberrant proteins then access the cell surface transiently before destruction in lysosomes. Inhibiting this stress-induced pathway by depleting the ER-export receptors leads to aggregation of the ER-retained misfolded protein. Thus, this rapid response alleviates the elevated burden of misfolded proteins in the ER at the onset of ER stress, promoting protein homeostasis in the ER.
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Affiliation(s)
- Prasanna Satpute-Krishnan
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA
| | - Monica Ajinkya
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA
| | - Savithri Bhat
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA
| | - Eisuke Itakura
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Ramanujan S Hegde
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
| | - Jennifer Lippincott-Schwartz
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA.
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217
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Maléth J, Balázs A, Pallagi P, Balla Z, Kui B, Katona M, Judák L, Németh I, Kemény LV, Rakonczay Z, Venglovecz V, Földesi I, Pető Z, Somorácz Á, Borka K, Perdomo D, Lukacs GL, Gray MA, Monterisi S, Zaccolo M, Sendler M, Mayerle J, Kühn JP, Lerch MM, Sahin-Tóth M, Hegyi P. Alcohol disrupts levels and function of the cystic fibrosis transmembrane conductance regulator to promote development of pancreatitis. Gastroenterology 2015; 148:427-39.e16. [PMID: 25447846 PMCID: PMC4353632 DOI: 10.1053/j.gastro.2014.11.002] [Citation(s) in RCA: 126] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 10/23/2014] [Accepted: 11/04/2014] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS Excessive consumption of ethanol is one of the most common causes of acute and chronic pancreatitis. Alterations to the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) also cause pancreatitis. However, little is known about the role of CFTR in the pathogenesis of alcohol-induced pancreatitis. METHODS We measured CFTR activity based on chloride concentrations in sweat from patients with cystic fibrosis, patients admitted to the emergency department because of excessive alcohol consumption, and healthy volunteers. We measured CFTR levels and localization in pancreatic tissues and in patients with acute or chronic pancreatitis induced by alcohol. We studied the effects of ethanol, fatty acids, and fatty acid ethyl esters on secretion of pancreatic fluid and HCO3(-), levels and function of CFTR, and exchange of Cl(-) for HCO3(-) in pancreatic cell lines as well as in tissues from guinea pigs and CFTR knockout mice after administration of alcohol. RESULTS Chloride concentrations increased in sweat samples from patients who acutely abused alcohol but not in samples from healthy volunteers, indicating that alcohol affects CFTR function. Pancreatic tissues from patients with acute or chronic pancreatitis had lower levels of CFTR than tissues from healthy volunteers. Alcohol and fatty acids inhibited secretion of fluid and HCO3(-), as well as CFTR activity, in pancreatic ductal epithelial cells. These effects were mediated by sustained increases in concentrations of intracellular calcium and adenosine 3',5'-cyclic monophosphate, depletion of adenosine triphosphate, and depolarization of mitochondrial membranes. In pancreatic cell lines and pancreatic tissues of mice and guinea pigs, administration of ethanol reduced expression of CFTR messenger RNA, reduced the stability of CFTR at the cell surface, and disrupted folding of CFTR at the endoplasmic reticulum. CFTR knockout mice given ethanol or fatty acids developed more severe pancreatitis than mice not given ethanol or fatty acids. CONCLUSIONS Based on studies of human, mouse, and guinea pig pancreata, alcohol disrupts expression and localization of the CFTR. This appears to contribute to development of pancreatitis. Strategies to increase CFTR levels or function might be used to treat alcohol-associated pancreatitis.
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Affiliation(s)
- József Maléth
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Anita Balázs
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Petra Pallagi
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Zsolt Balla
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Balázs Kui
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Máté Katona
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Linda Judák
- First Department of Medicine, University of Szeged, Szeged, Hungary,Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - István Németh
- Department of Dermatology and Allergology, University of Szeged, Szeged, Hungary
| | - Lajos V. Kemény
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Zoltán Rakonczay
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Viktória Venglovecz
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Imre Földesi
- Department of Laboratory Medicine, University of Szeged, Szeged, Hungary
| | - Zoltán Pető
- Department of Emergency Medicine, University of Szeged, Szeged, Hungary
| | - Áron Somorácz
- Second Department of Pathology, Semmelweis University, Budapest, Hungary
| | - Katalin Borka
- Second Department of Pathology, Semmelweis University, Budapest, Hungary
| | - Doranda Perdomo
- Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - Gergely L. Lukacs
- Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - Mike A. Gray
- Institute for Cell & Molecular Biosciences, Newcastle University, Newcastle upon Tyne, England
| | - Stefania Monterisi
- Department of Physiology, Anatomy and Genetics, Oxford University, Oxford, England
| | - Manuela Zaccolo
- Department of Physiology, Anatomy and Genetics, Oxford University, Oxford, England
| | - Matthias Sendler
- Department of Medicine A, University Medicine Greifswald, Greifswald, Germany
| | - Julia Mayerle
- Department of Medicine A, University Medicine Greifswald, Greifswald, Germany
| | - Jens-Peter Kühn
- Institute of Radiology, University Medicine, Ernst Moritz University, Greifswald, Germany
| | - Markus M. Lerch
- Department of Medicine A, University Medicine Greifswald, Greifswald, Germany
| | - Miklós Sahin-Tóth
- Department of Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, Massachusetts
| | - Péter Hegyi
- First Department of Medicine, University of Szeged, Szeged, Hungary; MTA-SZTE Lendület Translational Gastroenterology Research Group, Szeged, Hungary.
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218
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Young JC. The role of the cytosolic HSP70 chaperone system in diseases caused by misfolding and aberrant trafficking of ion channels. Dis Model Mech 2015; 7:319-29. [PMID: 24609033 PMCID: PMC3944492 DOI: 10.1242/dmm.014001] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Protein-folding diseases are an ongoing medical challenge. Many diseases within this group are genetically determined, and have no known cure. Among the examples in which the underlying cellular and molecular mechanisms are well understood are diseases driven by misfolding of transmembrane proteins that normally function as cell-surface ion channels. Wild-type forms are synthesized and integrated into the endoplasmic reticulum (ER) membrane system and, upon correct folding, are trafficked by the secretory pathway to the cell surface. Misfolded mutant forms traffic poorly, if at all, and are instead degraded by the ER-associated proteasomal degradation (ERAD) system. Molecular chaperones can assist the folding of the cytosolic domains of these transmembrane proteins; however, these chaperones are also involved in selecting misfolded forms for ERAD. Given this dual role of chaperones, diseases caused by the misfolding and aberrant trafficking of ion channels (referred to here as ion-channel-misfolding diseases) can be regarded as a consequence of insufficiency of the pro-folding chaperone activity and/or overefficiency of the chaperone ERAD role. An attractive idea is that manipulation of the chaperones might allow increased folding and trafficking of the mutant proteins, and thereby partial restoration of function. This Review outlines the roles of the cytosolic HSP70 chaperone system in the best-studied paradigms of ion-channel-misfolding disease--the CFTR chloride channel in cystic fibrosis and the hERG potassium channel in cardiac long QT syndrome type 2. In addition, other ion channels implicated in ion-channel-misfolding diseases are discussed.
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Affiliation(s)
- Jason C Young
- McGill University, Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, 3649 Promenade Sir William Osler, Montreal, QC H3G 0B1, Canada
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219
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Hara T, Hashimoto Y, Akuzawa T, Hirai R, Kobayashi H, Sato K. Rer1 and calnexin regulate endoplasmic reticulum retention of a peripheral myelin protein 22 mutant that causes type 1A Charcot-Marie-Tooth disease. Sci Rep 2014; 4:6992. [PMID: 25385046 PMCID: PMC4227013 DOI: 10.1038/srep06992] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 10/21/2014] [Indexed: 12/21/2022] Open
Abstract
Peripheral myelin protein 22 (PMP22) resides in the plasma membrane and is required for myelin formation in the peripheral nervous system. Many PMP22 mutants accumulate in excess in the endoplasmic reticulum (ER) and lead to the inherited neuropathies of Charcot-Marie-Tooth (CMT) disease. However, the mechanism through which PMP22 mutants accumulate in the ER is unknown. Here, we studied the quality control mechanisms for the PMP22 mutants L16P and G150D, which were originally identified in mice and patients with CMT. We found that the ER-localised ubiquitin ligase Hrd1/SYVN1 mediates ER-associated degradation (ERAD) of PMP22(L16P) and PMP22(G150D), and another ubiquitin ligase, gp78/AMFR, mediates ERAD of PMP22(G150D) as well. We also found that PMP22(L16P), but not PMP22(G150D), is partly released from the ER by loss of Rer1, which is a Golgi-localised sorting receptor for ER retrieval. Rer1 interacts with the wild-type and mutant forms of PMP22. Interestingly, release of PMP22(L16P) from the ER was more prominent with simultaneous knockdown of Rer1 and the ER-localised chaperone calnexin than with the knockdown of each gene. These results suggest that CMT disease-related PMP22(L16P) is trapped in the ER by calnexin-dependent ER retention and Rer1-mediated early Golgi retrieval systems and partly degraded by the Hrd1-mediated ERAD system.
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Affiliation(s)
- Taichi Hara
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
| | - Yukiko Hashimoto
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
| | - Tomoko Akuzawa
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
| | - Rika Hirai
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
| | - Hisae Kobayashi
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
| | - Ken Sato
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
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220
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Du K, Karp PH, Ackerley C, Zabner J, Keshavjee S, Cutz E, Yeger H. Aggregates of mutant CFTR fragments in airway epithelial cells of CF lungs: new pathologic observations. J Cyst Fibros 2014; 14:182-93. [PMID: 25453871 DOI: 10.1016/j.jcf.2014.09.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Revised: 09/24/2014] [Accepted: 09/25/2014] [Indexed: 01/12/2023]
Abstract
Cystic fibrosis (CF) is caused by a mutation in the CF transmembrane conductance regulator (CFTR) gene resulting in a loss of Cl(-) channel function, disrupting ion and fluid homeostasis, leading to severe lung disease with airway obstruction due to mucus plugging and inflammation. The most common CFTR mutation, F508del, occurs in 90% of patients causing the mutant CFTR protein to misfold and trigger an endoplasmic reticulum based recycling response. Despite extensive research into the pathobiology of CF lung disease, little attention has been paid to the cellular changes accounting for the pathogenesis of CF lung disease. Here we report a novel finding of intracellular retention and accumulation of a cleaved fragment of F508del CFTR in concert with autophagic like phagolysosomes in the airway epithelium of patients with F508del CFTR. Aggregates consisting of poly-ubiquitinylated fragments of only the N-terminal domain of F508del CFTR but not the full-length molecule accumulate to appreciable levels. Importantly, these undegraded intracytoplasmic aggregates representing the NT-NBD1 domain of F508del CFTR were found in ciliated, in basal, and in pulmonary neuroendocrine cells. Aggregates were found in both native lung tissues and ex-vivo primary cultures of bronchial epithelial cells from CF donors, but not in normal control lungs. Our findings present a new, heretofore, unrecognized innate CF gene related cell defect and a potential contributing factor to the pathogenesis of CF lung disease. Mutant CFTR intracytoplasmic aggregates could be analogous to the accumulation of misfolded proteins in other degenerative disorders and in pulmonary "conformational protein-associated" diseases. Consequently, potential alterations to the functional integrity of airway epithelium and regenerative capacity may represent a critical new element in the pathogenesis of CF lung disease.
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Affiliation(s)
- Kai Du
- Program in Developmental & Stem Cell Biology, Research Institute, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada.
| | - Philip H Karp
- Department of Medicine, The Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA; Department of Molecular Physiology and Biophysics, Howard Hughes Medical Institute, The Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Cameron Ackerley
- Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
| | - Joseph Zabner
- Department of Medicine, The Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Shaf Keshavjee
- Division of Experimental Therapeutics - Respiratory & Critical Care, Toronto General Research Institute (TGRI), Toronto, Ontario M5G 2C4, Canada; University of Toronto, Toronto, Ontario M5S 3G3, Canada
| | - Ernest Cutz
- Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada; University of Toronto, Toronto, Ontario M5S 3G3, Canada
| | - Herman Yeger
- Program in Developmental & Stem Cell Biology, Research Institute, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada; Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada; University of Toronto, Toronto, Ontario M5S 3G3, Canada.
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221
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Ramachandran S, Osterhaus SR, Karp PH, Welsh MJ, McCray PB. A genomic signature approach to rescue ΔF508-cystic fibrosis transmembrane conductance regulator biosynthesis and function. Am J Respir Cell Mol Biol 2014; 51:354-62. [PMID: 24669817 DOI: 10.1165/rcmb.2014-0007oc] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The most common cystic fibrosis (CF) mutation, ΔF508, causes protein misfolding, leading to proteosomal degradation. We recently showed that expression of miR-138 enhances CF transmembrane conductance regulator (CFTR) biogenesis and partially rescues ΔF508-CFTR function in CF airway epithelia. We hypothesized that a genomic signature approach can be used to identify new bioactive small molecules affecting ΔF508-CFTR rescue. The Connectivity Map was used to identify 27 small molecules with potential to restore ΔF508-CFTR function in airway epithelia. The molecules were screened in vitro for efficacy in improving ΔF508-CFTR trafficking, maturation, and chloride current. We identified four small molecules that partially restore ΔF508-CFTR function in primary CF airway epithelia. Of these, pyridostigmine showed cooperativity with corrector compound 18 in improving ΔF508-CFTR function. There are few CF therapies based on new molecular insights. Querying the Connectivity Map with relevant genomic signatures offers a method to identify new candidates for rescuing ΔF508-CFTR function.
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222
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Jaeger AM, Makley LN, Gestwicki JE, Thiele DJ. Genomic heat shock element sequences drive cooperative human heat shock factor 1 DNA binding and selectivity. J Biol Chem 2014; 289:30459-30469. [PMID: 25204655 DOI: 10.1074/jbc.m114.591578] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The heat shock transcription factor 1 (HSF1) activates expression of a variety of genes involved in cell survival, including protein chaperones, the protein degradation machinery, anti-apoptotic proteins, and transcription factors. Although HSF1 activation has been linked to amelioration of neurodegenerative disease, cancer cells exhibit a dependence on HSF1 for survival. Indeed, HSF1 drives a program of gene expression in cancer cells that is distinct from that activated in response to proteotoxic stress, and HSF1 DNA binding activity is elevated in cycling cells as compared with arrested cells. Active HSF1 homotrimerizes and binds to a DNA sequence consisting of inverted repeats of the pentameric sequence nGAAn, known as heat shock elements (HSEs). Recent comprehensive ChIP-seq experiments demonstrated that the architecture of HSEs is very diverse in the human genome, with deviations from the consensus sequence in the spacing, orientation, and extent of HSE repeats that could influence HSF1 DNA binding efficacy and the kinetics and magnitude of target gene expression. To understand the mechanisms that dictate binding specificity, HSF1 was purified as either a monomer or trimer and used to evaluate DNA-binding site preferences in vitro using fluorescence polarization and thermal denaturation profiling. These results were compared with quantitative chromatin immunoprecipitation assays in vivo. We demonstrate a role for specific orientations of extended HSE sequences in driving preferential HSF1 DNA binding to target loci in vivo. These studies provide a biochemical basis for understanding differential HSF1 target gene recognition and transcription in neurodegenerative disease and in cancer.
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Affiliation(s)
- Alex M Jaeger
- Departments of Pharmacology and Cancer Biology and Duke University School of Medicine, Durham, North Carolina 27710
| | - Leah N Makley
- Institute for Neurodegenerative Disease, University of California at San Francisco, San Francisco, California 94143
| | - Jason E Gestwicki
- Institute for Neurodegenerative Disease, University of California at San Francisco, San Francisco, California 94143
| | - Dennis J Thiele
- Departments of Pharmacology and Cancer Biology and Duke University School of Medicine, Durham, North Carolina 27710; Departments of Biochemistry, Duke University School of Medicine, Durham, North Carolina 27710 and.
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223
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Liu X, Dawson DC. Cystic fibrosis transmembrane conductance regulator (CFTR) potentiators protect G551D but not ΔF508 CFTR from thermal instability. Biochemistry 2014; 53:5613-8. [PMID: 25148434 PMCID: PMC4159205 DOI: 10.1021/bi501007v] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
![]()
The G551D cystic fibrosis transmembrane
conductance regulator (CFTR)
mutation is associated with severe disease in ∼5% of cystic
fibrosis patients worldwide. This amino acid substitution in NBD1
results in a CFTR chloride channel characterized by a severe gating
defect that can be at least partially overcome in vitro by exposure to a CFTR potentiator. In contrast, the more common
ΔF508 mutation is associated with a severe protein trafficking
defect, as well as impaired channel function. Recent clinical trials
demonstrated a beneficial effect of the CFTR potentiator, Ivacaftor
(VX-770), on lung function of patients bearing at least one copy of
G551D CFTR, but no comparable effect on ΔF508 homozygotes. This
difference in efficacy was not surprising in view of the established
difference in the molecular phenotypes of the two mutant channels.
Recently, however, it was shown that the structural defect introduced
by the deletion of F508 is associated with the thermal instability
of ΔF508 CFTR channel function in vitro. This
additional mutant phenotype raised the possibility that the differences
in the behavior of ΔF508 and G551D CFTR, as well as the disparate
efficacy of Ivacaftor, might be a reflection of the differing thermal
stabilities of the two channels at 37 °C. We compared the thermal
stability of G551D and ΔF508 CFTR in Xenopus oocytes in the presence and absence of CTFR potentiators. G551D
CFTR exhibited a thermal instability that was comparable to that of
ΔF508 CFTR. G551D CFTR, however, was protected from thermal
instability by CFTR potentiators, whereas ΔF508 CFTR was not.
These results suggest that the efficacy of VX-770 in patients bearing
the G551D mutation is due, at least in part, to the ability of the
small molecule to protect the mutant channel from thermal instability
at human body temperature.
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Affiliation(s)
- Xuehong Liu
- Department of Physiology & Pharmacology, Oregon Health & Science University , Portland, Oregon 97239, United States
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224
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Yamasaki A, Hara T, Maejima I, Sato M, Sato K, Sato K. Rer1p regulates the ER retention of immature rhodopsin and modulates its intracellular trafficking. Sci Rep 2014; 4:5973. [PMID: 25096327 PMCID: PMC4122963 DOI: 10.1038/srep05973] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Accepted: 07/21/2014] [Indexed: 11/18/2022] Open
Abstract
Rhodopsin is a pigment in photoreceptor cells. Some rhodopsin mutations cause the protein to accumulate in the endoplasmic reticulum (ER), leading to photoreceptor degeneration. Although several mutations have been reported, how mutant rhodopsin is retained in the ER remains unclear. In this study, we identified Rer1p as a modulator of ER retention and rhodopsin trafficking. Loss of Rer1p increased the transport of wild-type rhodopsin to post-Golgi compartments. Overexpression of Rer1p caused immature wild-type rhodopsin to accumulate in the ER. Interestingly, the G51R rhodopsin mutant, which has a mutation in the first transmembrane domain and accumulates in the ER, was released to the plasma membrane or lysosomes in Rer1-knockdown cells. Consistent with these results, Rer1p interacted with both wild-type and mutant rhodopsin. These results suggest that Rer1p regulates the ER retention of immature or misfolded rhodopsin and modulates its intracellular trafficking through the early secretory pathway.
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Affiliation(s)
- Akinori Yamasaki
- 1] Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan [2]
| | - Taichi Hara
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
| | - Ikuko Maejima
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
| | - Miyuki Sato
- 1] Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan [2] Laboratory of Molecular Membrane Biology, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
| | - Katsuya Sato
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
| | - Ken Sato
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
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225
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Chen JH. A cocktail drug therapy for patients with cystic fibrosis? J Cyst Fibros 2014; 13:489-90. [PMID: 25088968 DOI: 10.1016/j.jcf.2014.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/10/2014] [Indexed: 10/25/2022]
Affiliation(s)
- Jeng-Haur Chen
- Department of Physiology, HKU Shenzhen Institute of Research and Innovation, University of Hong Kong, Li Ka Shing Faculty of Medicine, Faculty of Medicine Building, 21 Sassoon Road, Pokfulam, Hong Kong, China.
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226
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Chu CY, King J, Berrini M, Rumley AC, Apaja PM, Lukacs GL, Alexander RT, Cordat E. Degradation mechanism of a Golgi-retained distal renal tubular acidosis mutant of the kidney anion exchanger 1 in renal cells. Am J Physiol Cell Physiol 2014; 307:C296-307. [DOI: 10.1152/ajpcell.00310.2013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Distal renal tubular acidosis (dRTA) can be caused by mutations in the SLC4A1 gene encoding the anion exchanger 1 (AE1). Both recessive and dominant mutations result in mistrafficking of proteins, preventing them from reaching the basolateral membrane of renal epithelial cells, where their function is needed. In this study, we show that two dRTA mutants are prematurely degraded. Therefore, we investigated the degradation pathway of the kidney AE1 G701D mutant that is retained in the Golgi. Little is known about degradation of nonnative membrane proteins from the Golgi compartments in mammalian cells. We show that the kidney AE1 G701D mutant is polyubiquitylated and degraded by the lysosome and the proteosome. This mutant reaches the plasma membrane, where it is endocytosed and degraded by the lysosome via a mechanism dependent on the peripheral quality control machinery. Furthermore, we show that the function of the mutant is rescued at the cell surface upon inhibition of the lysosome and incubation with a chemical chaperone. We conclude that modulating the peripheral quality control machinery may provide a novel therapeutic option for treatment of patients with dRTA due to a Golgi-retained mutant.
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Affiliation(s)
- Carmen Y. Chu
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada; and
| | - Jennifer King
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada; and
| | - Mattia Berrini
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada; and
| | - Alina C. Rumley
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada; and
| | - Pirjo M. Apaja
- Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - Gergely L. Lukacs
- Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - R. Todd Alexander
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada; and
| | - Emmanuelle Cordat
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada; and
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227
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Quality control of plasma membrane proteins by Saccharomyces cerevisiae Nedd4-like ubiquitin ligase Rsp5p under environmental stress conditions. EUKARYOTIC CELL 2014; 13:1191-9. [PMID: 25001409 DOI: 10.1128/ec.00104-14] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In Saccharomyces cerevisiae, when a rich nitrogen source such as ammonium is added to the culture medium, the general amino acid permease Gap1p is ubiquitinated by the yeast Nedd4-like ubiquitin ligase Rsp5p, followed by its endocytosis to the vacuole. The arrestin-like Bul1/2p adaptors for Rsp5p specifically mediate this process. In this study, to investigate the downregulation of Gap1p in response to environmental stresses, we determined the intracellular trafficking of Gap1p under various stress conditions. An increase in the extracellular ethanol concentration induced ubiquitination and trafficking of Gap1p from the plasma membrane to the vacuole in wild-type cells, whereas Gap1p remained stable on the plasma membrane under the same conditions in rsp5(A401E) and Δend3 cells. A (14)C-labeled citrulline uptake assay using a nonubiquitinated form of Gap1p (Gap1p(K9R/K16R)) revealed that ethanol stress caused a dramatic decrease of Gap1p activity. These results suggest that Gap1p is inactivated and ubiquitinated by Rsp5p for endocytosis when S. cerevisiae cells are exposed to a high concentration of ethanol. It is noteworthy that this endocytosis occurs in a Bul1/2p-independent manner, whereas ammonium-triggered downregulation of Gap1p was almost completely inhibited in Δbul1/2 cells. We also found that other environmental stresses, such as high temperature, H₂O₂, and LiCl, also promoted endocytosis of Gap1p. Similar intracellular trafficking caused by ethanol occurred in other plasma membrane proteins (Agp1p, Tat2p, and Gnp1p). Our findings suggest that stress-induced quality control is a common process requiring Rsp5p for plasma membrane proteins in yeast.
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228
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Pranke IM, Sermet-Gaudelus I. Biosynthesis of cystic fibrosis transmembrane conductance regulator. Int J Biochem Cell Biol 2014; 52:26-38. [DOI: 10.1016/j.biocel.2014.03.020] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2014] [Revised: 03/19/2014] [Accepted: 03/20/2014] [Indexed: 01/19/2023]
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229
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Arora K, Moon C, Zhang W, Yarlagadda S, Penmatsa H, Ren A, Sinha C, Naren AP. Stabilizing rescued surface-localized δf508 CFTR by potentiation of its interaction with Na(+)/H(+) exchanger regulatory factor 1. Biochemistry 2014; 53:4169-79. [PMID: 24945463 PMCID: PMC4081048 DOI: 10.1021/bi401263h] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
![]()
Cystic
fibrosis (CF) is a recessive genetic disease caused by mutations
in CFTR, a plasma-membrane-localized anion channel. The most common
mutation in CFTR, deletion of phenylalanine at residue 508 (ΔF508),
causes misfolding of CFTR resulting in little or no protein at the
plasma membrane. The CFTR corrector VX-809 shows promise for treating
CF patients homozygous for ΔF508. Here, we demonstrate the significance
of protein–protein interactions in enhancing the stability
of the ΔF508 CFTR mutant channel protein at the plasma membrane.
We determined that VX-809 prolongs the stability of ΔF508 CFTR
at the plasma membrane. Using competition-based assays, we demonstrated
that ΔF508 CFTR interacts poorly with Na+/H+ exchanger regulatory factor 1 (NHERF1) compared to wild-type CFTR,
and VX-809 significantly increased this binding affinity. We conclude
that stabilized CFTR–NHERF1 interaction is a determinant of
the functional efficiency of rescued ΔF508 CFTR. Our results
demonstrate the importance of macromolecular-complex formation in
stabilizing rescued mutant CFTR at the plasma membrane and suggest
this to be foundational for the development of a new generation of
effective CFTR-corrector-based therapeutics.
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Affiliation(s)
- Kavisha Arora
- Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center , MLC2021 3333 Burnet Avenue, Cincinnati, Ohio 45229, United States
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230
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MacGurn JA. Garbage on, garbage off: new insights into plasma membrane protein quality control. Curr Opin Cell Biol 2014; 29:92-8. [PMID: 24908345 DOI: 10.1016/j.ceb.2014.05.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 04/10/2014] [Accepted: 05/10/2014] [Indexed: 01/22/2023]
Abstract
Maintenance of cellular protein quality - by restoring misfolded proteins to their native state and by targeting terminally misfolded or damaged proteins for degradation - is a critical function of all cells. To ensure protein quality, cells have evolved various organelle-specific quality control mechanisms responsible for recognizing and responding to misfolded proteins at different subcellular locations of the cell. Recently, several publications have begun to elucidate mechanisms of quality control that operate at the plasma membrane (PM), recognizing misfolded PM proteins and targeting their endocytic trafficking and lysosomal degradation. Here, I discuss these recent developments in our understanding of PM quality control mechanisms and how they relate to global protein quality control strategies in the cell.
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Affiliation(s)
- Jason A MacGurn
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232-8240, USA.
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231
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Babst M. Quality control: quality control at the plasma membrane: one mechanism does not fit all. ACTA ACUST UNITED AC 2014; 205:11-20. [PMID: 24733583 PMCID: PMC3987138 DOI: 10.1083/jcb.201310113] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The plasma membrane quality control system of eukaryotic cells is able to recognize and degrade damaged cell surface proteins. Recent studies have identified two mechanisms involved in the recognition of unfolded transmembrane proteins. One system uses chaperones to detect unfolded cytoplasmic domains of transmembrane proteins, whereas the second mechanism relies on an internal quality control system of the protein, which can trigger degradation when the protein deviates from the folded state. Both quality control mechanisms are key to prevent proteotoxic effects at the cell surface and to ensure cell integrity.
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Affiliation(s)
- Markus Babst
- Department of Biology, Center for Cell and Genome Science, University of Utah, Salt Lake City, UT 84112
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232
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Favia M, Mancini MT, Bezzerri V, Guerra L, Laselva O, Abbattiscianni AC, Debellis L, Reshkin SJ, Gambari R, Cabrini G, Casavola V. Trimethylangelicin promotes the functional rescue of mutant F508del CFTR protein in cystic fibrosis airway cells. Am J Physiol Lung Cell Mol Physiol 2014; 307:L48-61. [PMID: 24816489 DOI: 10.1152/ajplung.00305.2013] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Cystic fibrosis transmembrane conductance regulator (CFTR) carrying the F508del mutation is retained in endoplasmic reticulum and fails to traffic to the cell surface where it functions as a protein kinase A (PKA)-activated chloride channel. Pharmacological correctors that rescue the trafficking of F508del CFTR may overcome this defect; however, the rescued F508del CFTR still displays reduced chloride permeability. Therefore, a combined administration of correctors and potentiators of the gating defect is ideal. We recently found that 4,6,4'-trimethylangelicin (TMA), besides inhibiting the expression of the IL-8 gene in airway cells in which the inflammatory response was challenged with Pseudomonas aeruginosa, also potentiates the cAMP/PKA-dependent activation of wild-type CFTR or F508del CFTR that has been restored to the plasma membrane. Here, we demonstrate that long preincubation with nanomolar concentrations of TMA is able to effectively rescue both F508del CFTR-dependent chloride secretion and F508del CFTR cell surface expression in both primary or secondary airway cell monolayers homozygous for F508del mutation. The correction effect of TMA seems to be selective for CFTR and persisted for 24 h after washout. Altogether, the results suggest that TMA, besides its anti-inflammatory and potentiator activities, also displays corrector properties.
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Affiliation(s)
- Maria Favia
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Maria T Mancini
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Valentino Bezzerri
- Laboratory of Molecular Pathology, Department of Pathology and Diagnostics, University Hospital Verona, Verona, Italy
| | - Lorenzo Guerra
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Onofrio Laselva
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Anna C Abbattiscianni
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Lucantonio Debellis
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Stephan J Reshkin
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Roberto Gambari
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy; and
| | - Giulio Cabrini
- Laboratory of Molecular Pathology, Department of Pathology and Diagnostics, University Hospital Verona, Verona, Italy
| | - Valeria Casavola
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy; Centre of Excellence in Comparative Genomics, University of Bari, Bari, Italy
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233
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Decoding F508del misfolding in cystic fibrosis. Biomolecules 2014; 4:498-509. [PMID: 24970227 PMCID: PMC4101494 DOI: 10.3390/biom4020498] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 04/11/2014] [Accepted: 04/25/2014] [Indexed: 01/13/2023] Open
Abstract
The functional deficiency of the cystic fibrosis transmembrane conductance regulator (CFTR), a plasma membrane chloride channel, leads to the development of cystic fibrosis. The deletion of a phenylalanine at residue 508 (F508del) is the most common cause of CFTR misfolding leading to the disease. The F508del misfolding originates in the first nucleotide-binding domain (NBD1), which induces a global conformational change in CFTR through NBD1’s interactions with other domains. Such global misfolding produces a mutant chloride channel that is impaired in exocytic trafficking, peripheral stability, and channel gating. The nature and atomic details of F508del misfolding have been subject to extensive research during the past decade. Current data support a central role for NBD1 in F508del misfolding and rescue. Many cis-acting NBD1 second-site mutations rescue F508del misfolding in the context of full-length CFTR. While some of these mutations appear to specifically counteract the F508del-induced misfolding, others release certain inherent conformational constraints of the human wild-type CFTR. Several small-molecule correctors were recently found to act on key interdomain interfaces of F508del CFTR. Potential rational approaches have been proposed in an attempt to develop highly effective small molecule modulators that improve the cell surface functional expression of F508del CFTR.
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Eckford P, Ramjeesingh M, Molinski S, Pasyk S, Dekkers JF, Li C, Ahmadi S, Ip W, Chung T, Du K, Yeger H, Beekman J, Gonska T, Bear C. VX-809 and Related Corrector Compounds Exhibit Secondary Activity Stabilizing Active F508del-CFTR after Its Partial Rescue to the Cell Surface. ACTA ACUST UNITED AC 2014; 21:666-78. [DOI: 10.1016/j.chembiol.2014.02.021] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Revised: 02/22/2014] [Accepted: 02/25/2014] [Indexed: 12/11/2022]
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Phuan PW, Veit G, Tan J, Roldan A, Finkbeiner WE, Lukacs GL, Verkman AS. Synergy-based small-molecule screen using a human lung epithelial cell line yields ΔF508-CFTR correctors that augment VX-809 maximal efficacy. Mol Pharmacol 2014; 86:42-51. [PMID: 24737137 DOI: 10.1124/mol.114.092478] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The most prevalent cystic fibrosis transmembrane conductance regulator (CFTR) mutation causing cystic fibrosis, ΔF508, impairs folding of nucleotide binding domain (NBD) 1 and stability of the interface between NBD1 and the membrane-spanning domains. The interfacial stability defect can be partially corrected by the investigational drug VX-809 (3-[6-[[[1-(2,2-difluoro-1,3-benzodioxol-5-yl)cyclopropyl]carbonyl]amino]-3-methyl-2-pyridinyl]-benzoic acid) or the R1070W mutation. Second-generation ΔF508-CFTR correctors are needed to improve on the modest efficacy of existing cystic fibrosis correctors. We postulated that a second corrector targeting a distinct folding/interfacial defect might act in synergy with VX-809 or the R1070W suppressor mutation. A biochemical screen for ΔF508-CFTR cell surface expression was developed in a human lung epithelium-derived cell line (CFBE41o(-)) by expressing chimeric CFTRs with a horseradish peroxidase (HRP) in the fourth exofacial loop in either the presence or absence of R1070W. Using a luminescence readout of HRP activity, screening of approximately 110,000 small molecules produced nine novel corrector scaffolds that increased cell surface ∆F508-CFTR expression by up to 200% in the presence versus absence of maximal VX-809. Further screening of 1006 analogs of compounds identified from the primary screen produced 15 correctors with an EC50 < 5 µM. Eight chemical scaffolds showed synergy with VX-809 in restoring chloride permeability in ∆F508-expressing A549 cells. An aminothiazole increased chloride conductance in human bronchial epithelial cells from a ΔF508 homozygous subject beyond that of maximal VX-809. Mechanistic studies suggested that NBD2 is required for the aminothiazole rescue. Our results provide proof of concept for synergy screening to identify second-generation correctors, which, when used in combination, may overcome the "therapeutic ceiling" of first-generation correctors.
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Affiliation(s)
- Puay-Wah Phuan
- Departments of Medicine and Physiology (P.-W.P., J.T., A.S.V.) and Department of Pathology (W.E.F.), University of California, San Francisco, California; and Groupe de Recherche Axé sur la Structure des Protéine and Departments of Physiology (G.V., A.R., G.L.L.) and Biochemistry (G.L.L.), McGill University, Montreal, Quebec, Canada
| | - Guido Veit
- Departments of Medicine and Physiology (P.-W.P., J.T., A.S.V.) and Department of Pathology (W.E.F.), University of California, San Francisco, California; and Groupe de Recherche Axé sur la Structure des Protéine and Departments of Physiology (G.V., A.R., G.L.L.) and Biochemistry (G.L.L.), McGill University, Montreal, Quebec, Canada
| | - Joseph Tan
- Departments of Medicine and Physiology (P.-W.P., J.T., A.S.V.) and Department of Pathology (W.E.F.), University of California, San Francisco, California; and Groupe de Recherche Axé sur la Structure des Protéine and Departments of Physiology (G.V., A.R., G.L.L.) and Biochemistry (G.L.L.), McGill University, Montreal, Quebec, Canada
| | - Ariel Roldan
- Departments of Medicine and Physiology (P.-W.P., J.T., A.S.V.) and Department of Pathology (W.E.F.), University of California, San Francisco, California; and Groupe de Recherche Axé sur la Structure des Protéine and Departments of Physiology (G.V., A.R., G.L.L.) and Biochemistry (G.L.L.), McGill University, Montreal, Quebec, Canada
| | - Walter E Finkbeiner
- Departments of Medicine and Physiology (P.-W.P., J.T., A.S.V.) and Department of Pathology (W.E.F.), University of California, San Francisco, California; and Groupe de Recherche Axé sur la Structure des Protéine and Departments of Physiology (G.V., A.R., G.L.L.) and Biochemistry (G.L.L.), McGill University, Montreal, Quebec, Canada
| | - Gergely L Lukacs
- Departments of Medicine and Physiology (P.-W.P., J.T., A.S.V.) and Department of Pathology (W.E.F.), University of California, San Francisco, California; and Groupe de Recherche Axé sur la Structure des Protéine and Departments of Physiology (G.V., A.R., G.L.L.) and Biochemistry (G.L.L.), McGill University, Montreal, Quebec, Canada
| | - A S Verkman
- Departments of Medicine and Physiology (P.-W.P., J.T., A.S.V.) and Department of Pathology (W.E.F.), University of California, San Francisco, California; and Groupe de Recherche Axé sur la Structure des Protéine and Departments of Physiology (G.V., A.R., G.L.L.) and Biochemistry (G.L.L.), McGill University, Montreal, Quebec, Canada
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Wang Y, Wrennall JA, Cai Z, Li H, Sheppard DN. Understanding how cystic fibrosis mutations disrupt CFTR function: from single molecules to animal models. Int J Biochem Cell Biol 2014; 52:47-57. [PMID: 24727426 DOI: 10.1016/j.biocel.2014.04.001] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 04/01/2014] [Accepted: 04/02/2014] [Indexed: 12/21/2022]
Abstract
Defective epithelial ion transport is the hallmark of the life-limiting genetic disease cystic fibrosis (CF). This abnormality is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR), the ATP-binding cassette transporter that functions as a ligand-gated anion channel. Since the identification of the CFTR gene, almost 2000 disease-causing mutations associated with a spectrum of clinical phenotypes have been reported, but the majority remain poorly characterised. Studies of a small number of mutations including the most common, F508del-CFTR, have identified six general mechanisms of CFTR dysfunction. Here, we review selectively progress to understand how CF mutations disrupt CFTR processing, stability and function. We explore CFTR structure and function to explain the molecular mechanisms of CFTR dysfunction and highlight new knowledge of disease pathophysiology emerging from large animal models of CF. Understanding CFTR dysfunction is crucial to the development of transformational therapies for CF patients.
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Affiliation(s)
- Yiting Wang
- School of Physiology and Pharmacology, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Joe A Wrennall
- School of Physiology and Pharmacology, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Zhiwei Cai
- School of Physiology and Pharmacology, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Hongyu Li
- School of Physiology and Pharmacology, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - David N Sheppard
- School of Physiology and Pharmacology, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK.
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Bomberger JM, Coutermarsh BA, Barnaby RL, Sato JD, Chapline MC, Stanton BA. Serum and glucocorticoid-inducible kinase1 increases plasma membrane wt-CFTR in human airway epithelial cells by inhibiting its endocytic retrieval. PLoS One 2014; 9:e89599. [PMID: 24586903 PMCID: PMC3931797 DOI: 10.1371/journal.pone.0089599] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 01/23/2014] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Chloride (Cl) secretion by the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) located in the apical membrane of respiratory epithelial cells plays a critical role in maintenance of the airway surface liquid and mucociliary clearance of pathogens. Previously, we and others have shown that the serum and glucocorticoid-inducible kinase-1 (SGK1) increases wild type CFTR (wt-CFTR) mediated Cl transport in Xenopus oocytes by increasing the amount of wt-CFTR protein in the plasma membrane. However, the effect of SGK1 on the membrane abundance of wt-CFTR in airway epithelial cells has not been examined, and the mechanism whereby SGK1 increases membrane wt-CFTR has also not been examined. Thus, the goal of this study was to elucidate the mechanism whereby SGK1 regulates the membrane abundance of wt-CFTR in human airway epithelial cells. METHODS AND RESULTS We report that elevated levels of SGK1, induced by dexamethasone, increase plasma membrane abundance of wt-CFTR. Reduction of SGK1 expression by siRNA (siSGK1) and inhibition of SGK1 activity by the SGK inhibitor GSK 650394 abrogated the ability of dexamethasone to increase plasma membrane wt-CFTR. Overexpression of a constitutively active SGK1 (SGK1-S422D) increased plasma membrane abundance of wt-CFTR. To understand the mechanism whereby SGK1 increased plasma membrane wt-CFTR, we examined the effects of siSGK1 and SGK1-S442D on the endocytic retrieval of wt-CFTR. While siSGK1 increased wt-CFTR endocytosis, SGK1-S442D inhibited CFTR endocytosis. Neither siSGK1 nor SGK1-S442D altered the recycling of endocytosed wt-CFTR back to the plasma membrane. By contrast, SGK1 increased the endocytosis of the epidermal growth factor receptor (EGFR). CONCLUSION This study demonstrates for the first time that SGK1 selectively increases wt-CFTR in the plasma membrane of human airway epithelia cells by inhibiting its endocytic retrieval from the membrane.
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Affiliation(s)
- Jennifer M. Bomberger
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Bonita A. Coutermarsh
- Department of Microbiology and Immunology and of Physiology, The Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
| | - Roxanna L. Barnaby
- Department of Microbiology and Immunology and of Physiology, The Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
| | - J. Denry Sato
- Mt. Desert Island Biological Laboratory, Salisbury Cove, Maine, United States of America
| | - M. Christine Chapline
- Mt. Desert Island Biological Laboratory, Salisbury Cove, Maine, United States of America
| | - Bruce A. Stanton
- Department of Microbiology and Immunology and of Physiology, The Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
- Mt. Desert Island Biological Laboratory, Salisbury Cove, Maine, United States of America
- * E-mail:
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Rasmussen JE, Sheridan JT, Polk W, Davies CM, Tarran R. Cigarette smoke-induced Ca2+ release leads to cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction. J Biol Chem 2014; 289:7671-81. [PMID: 24448802 DOI: 10.1074/jbc.m113.545137] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Chronic obstructive pulmonary disease affects 64 million people and is currently the fourth leading cause of death worldwide. Chronic obstructive pulmonary disease includes both emphysema and chronic bronchitis, and in the case of chronic bronchitis represents an inflammatory response of the airways that is associated with mucus hypersecretion and obstruction of small airways. Recently, it has emerged that exposure to cigarette smoke (CS) leads to an inhibition of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel, causing airway surface liquid dehydration, which may play a role in the development of chronic bronchitis. CS rapidly clears CFTR from the plasma membrane and causes it to be deposited into aggresome-like compartments. However, little is known about the mechanism(s) responsible for the internalization of CFTR following CS exposure. Our studies revealed that CS triggered a rise in cytoplasmic Ca(2+) that may have emanated from lysosomes. Furthermore, chelation of cytoplasmic Ca(2+), but not inhibition of protein kinases/phosphatases, prevented CS-induced CFTR internalization. The macrolide antibiotic bafilomycin A1 inhibited CS-induced Ca(2+) release and prevented CFTR clearance from the plasma membrane, further linking cytoplasmic Ca(2+) and CFTR internalization. We hypothesize that CS-induced Ca(2+) release prevents normal sorting/degradation of CFTR and causes internalized CFTR to reroute to aggresomes. Our data provide mechanistic insight into the potentially deleterious effects of CS on airway epithelia and outline a hitherto unrecognized signaling event triggered by CS that may affect the long term transition of the lung into a hyper-inflammatory/dehydrated environment.
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Csanády L, Töröcsik B. Catalyst-like modulation of transition states for CFTR channel opening and closing: new stimulation strategy exploits nonequilibrium gating. ACTA ACUST UNITED AC 2014; 143:269-87. [PMID: 24420771 PMCID: PMC4001772 DOI: 10.1085/jgp.201311089] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Two gating transition states determine open probability of CFTR (the chloride channel mutated in cystic fibrosis), defining strategic targets for therapeutic intervention. Cystic fibrosis transmembrane conductance regulator (CFTR) is the chloride ion channel mutated in cystic fibrosis (CF) patients. It is an ATP-binding cassette protein, and its resulting cyclic nonequilibrium gating mechanism sets it apart from most other ion channels. The most common CF mutation (ΔF508) impairs folding of CFTR but also channel gating, reducing open probability (Po). This gating defect must be addressed to effectively treat CF. Combining single-channel and macroscopic current measurements in inside-out patches, we show here that the two effects of 5-nitro-2-(3-phenylpropylamino)benzoate (NPPB) on CFTR, pore block and gating stimulation, are independent, suggesting action at distinct sites. Furthermore, detailed kinetic analysis revealed that NPPB potently increases Po, also of ΔF508 CFTR, by affecting the stability of gating transition states. This finding is unexpected, because for most ion channels, which gate at equilibrium, altering transition-state stabilities has no effect on Po; rather, agonists usually stimulate by stabilizing open states. Our results highlight how for CFTR, because of its unique cyclic mechanism, gating transition states determine Po and offer strategic targets for potentiator compounds to achieve maximal efficacy.
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Affiliation(s)
- László Csanády
- Department of Medical Biochemistry and 2 MTA-SE Ion Channel Research Group, Semmelweis University, Budapest H-1094, Hungary
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Zaman K, Bennett D, Fraser-Butler M, Greenberg Z, Getsy P, Sattar A, Smith L, Corey D, Sun F, Hunt J, Lewis SJ, Gaston B. S-Nitrosothiols increases cystic fibrosis transmembrane regulator expression and maturation in the cell surface. Biochem Biophys Res Commun 2014; 443:1257-62. [PMID: 24393850 DOI: 10.1016/j.bbrc.2013.12.130] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 12/24/2013] [Indexed: 11/29/2022]
Abstract
S-nitrosothiols (SNOs) are endogenous signaling molecules with a broad spectrum of beneficial airway effects. SNOs are normally present in the airway, but levels tend to be low in cystic fibrosis (CF) patients. We and others have demonstrated that S-nitrosoglutathione (GSNO) increases the expression, maturation, and function of wild-type and mutant F508del cystic fibrosis transmembrane conductance regulator (CFTR) in human bronchial airway epithelial (HBAE) cells. We hypothesized that membrane permeable SNOs, such as S-nitrosoglutathione diethyl ester (GNODE) and S-nitroso-N-acetyl cysteine (SNOAC) may be more efficient in increasing the maturation of CFTR. HBAE cells expressing F508del CFTR were exposed to GNODE and SNOAC. The effects of these SNOs on the expression and maturation of F508del CFTR were determined by cell surface biotinylation and Western blot analysis. We also found for the first time that GNODE and SNOAC were effective at increasing CFTR maturation at the cell surface. Furthermore, we found that cells maintained at low temperature increased cell surface stability of F508del CFTR whereas the combination of low temperature and SNO treatment significantly extended the half-life of CFTR. Finally, we showed that SNO decreased the internalization rate of F508del CFTR in HBAE cells. We anticipate identifying the novel mechanisms, optimal SNOs, and lowest effective doses which could benefit cystic fibrosis patients.
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Affiliation(s)
- Khalequz Zaman
- Pediatric Pulmonology Division, Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.
| | - Deric Bennett
- Pediatric Respiratory Medicine, Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Maya Fraser-Butler
- Pediatric Respiratory Medicine, Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Zivi Greenberg
- Pediatric Respiratory Medicine, Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Paulina Getsy
- Pediatric Pulmonology Division, Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Abdus Sattar
- Epidemiology and Biostatistics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Laura Smith
- Pediatric Pulmonology Division, Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Deborah Corey
- Pediatric Pulmonology Division, Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Fei Sun
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - John Hunt
- Pediatric Respiratory Medicine, Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Stephen J Lewis
- Pediatric Pulmonology Division, Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Benjamin Gaston
- Pediatric Pulmonology Division, Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
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Welling PA. Rare mutations in renal sodium and potassium transporter genes exhibit impaired transport function. Curr Opin Nephrol Hypertens 2014; 23:1-8. [PMID: 24253496 PMCID: PMC4007692 DOI: 10.1097/01.mnh.0000437204.84826.99] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
PURPOSE OF REVIEW Recent efforts to explore the genetic underpinnings of hypertension revealed rare mutations in kidney salt transport genes contribute to blood pressure (BP) variation and hypertension susceptibility in the general population. The current review focuses on these latest findings, highlighting a discussion about the rare mutations and how they affect the transport function. RECENT FINDINGS Rare mutations that confer a low BP trait and resistance to hypertension have recently been extensively studied. Physiological and biochemical analyses of the affected renal salt transport molecules [NKCC2 (SLC12A1), ROMK (KCNJ1), and NCC (SLC12A3)] revealed that most of the mutations do, in fact, cause a loss of transport function. The mutations disrupt the transport by many different mechanisms, including altering biosynthetic processing, trafficking, ion transport, and regulation. SUMMARY New insights into the genetic basis of hypertension have recently emerged, supporting a major role of rare, rather than common, gene variants. Many different rare mutations have been found to affect the functions of different salt transporter genes by different mechanisms, yet all confer the same BP phenotype. These studies reinforce the critical roles of the kidney, and renal salt transport in BP regulation and hypertension.
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Affiliation(s)
- Paul A. Welling
- Department of Physiology, University of Maryland Medical School, Baltimore, MD 21201, Telephone: 410-706-3851
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Piper RC, Dikic I, Lukacs GL. Ubiquitin-dependent sorting in endocytosis. Cold Spring Harb Perspect Biol 2014; 6:6/1/a016808. [PMID: 24384571 DOI: 10.1101/cshperspect.a016808] [Citation(s) in RCA: 155] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
When ubiquitin (Ub) is attached to membrane proteins on the plasma membrane, it directs them through a series of sorting steps that culminate in their delivery to the lumen of the lysosome where they undergo complete proteolysis. Ubiquitin is recognized by a series of complexes that operate at a number of vesicle transport steps. Ubiquitin serves as a sorting signal for internalization at the plasma membrane and is the major signal for incorporation into intraluminal vesicles of multivesicular late endosomes. The sorting machineries that catalyze these steps can bind Ub via a variety of Ub-binding domains. At the same time, many of these complexes are themselves ubiquitinated, thus providing a plethora of potential mechanisms to regulate their activity. Here we provide an overview of how membrane proteins are selected for ubiquitination and deubiquitination within the endocytic pathway and how that ubiquitin signal is interpreted by endocytic sorting machineries.
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Affiliation(s)
- Robert C Piper
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa 52242
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Ionenkanäle – Einführung aus physiologischer Perspektive. MED GENET-BERLIN 2013. [DOI: 10.1007/s11825-013-0428-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Zusammenfassung
Ionenkanäle bilden eine vielfältige Klasse von Transportmembranproteinen. Sie können nach Selektivität der Ionenspezies und der Kontrolle ihres Schaltverhaltens z. B. durch Membranpotenzial oder Bindung von Liganden klassifiziert werden. Der Transport durch Kanalproteine besitzt sowohl eine elektrische wie eine chemische Dimension. Die mit dem selektiven Ionentransport über Membranen einhergehende Ladungstrennung bewirkt eine Veränderung des Membranpotenzials, der Ionenfluss führt parallel zu einer Veränderung von Ionenkonzentrationen. Basierend auf dieser elektrochemischen Doppelnatur der Ionenkanäle lassen sich aus physiologischer Perspektive 2 Funktionsbereiche differenzieren. In erregbaren Zellen steht die Steuerung des Membranpotenzials zur Erzeugung schneller elektrischer Signale im Vordergrund, während gerichteter Ionentransport bei Transportepithelien die zentrale Größe darstellt. So stehen bei einzelnen Ionenkanalkrankheiten meist Erregungs – oder Transportstörungen im Vordergrund.
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Kolb AR, Needham PG, Rothenberg C, Guerriero CJ, Welling PA, Brodsky JL. ESCRT regulates surface expression of the Kir2.1 potassium channel. Mol Biol Cell 2013; 25:276-89. [PMID: 24227888 PMCID: PMC3890348 DOI: 10.1091/mbc.e13-07-0394] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The Kir2.1 potassium channel is targeted by endoplasmic reticulum–associated degradation in yeast. To identify other Kir2.1 quality control factors, a novel yeast screen was performed. ESCRT components were among the strongest hits from the screen. Consistent with these data, ESCRT also regulates Kir2.1 stability in human cells. Protein quality control (PQC) is required to ensure cellular health. PQC is recognized for targeting the destruction of defective polypeptides, whereas regulated protein degradation mechanisms modulate the concentration of specific proteins in concert with physiological demands. For example, ion channel levels are physiologically regulated within tight limits, but a system-wide approach to define which degradative systems are involved is lacking. We focus on the Kir2.1 potassium channel because altered Kir2.1 levels lead to human disease and Kir2.1 restores growth on low-potassium medium in yeast mutated for endogenous potassium channels. Using this system, first we find that Kir2.1 is targeted for endoplasmic reticulum–associated degradation (ERAD). Next a synthetic gene array identifies nonessential genes that negatively regulate Kir2.1. The most prominent gene family that emerges from this effort encodes members of endosomal sorting complex required for transport (ESCRT). ERAD and ESCRT also mediate Kir2.1 degradation in human cells, with ESCRT playing a more prominent role. Thus multiple proteolytic pathways control Kir2.1 levels at the plasma membrane.
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Affiliation(s)
- Alexander R Kolb
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15261 Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201
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Lazrak A, Fu L, Bali V, Bartoszewski R, Rab A, Havasi V, Keiles S, Kappes J, Kumar R, Lefkowitz E, Sorscher EJ, Matalon S, Collawn JF, Bebok Z. The silent codon change I507-ATC->ATT contributes to the severity of the ΔF508 CFTR channel dysfunction. FASEB J 2013; 27:4630-45. [PMID: 23907436 PMCID: PMC4046180 DOI: 10.1096/fj.13-227330] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 07/15/2013] [Indexed: 01/08/2023]
Abstract
The most common disease-causing mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene is the out-of-frame deletion of 3 nucleotides (CTT). This mutation leads to the loss of phenylalanine-508 (ΔF508) and a silent codon change (SCC) for isoleucine-507 (I507-ATC→ATT). ΔF508 CFTR is misfolded and degraded by endoplasmic reticulum-associated degradation (ERAD). We have demonstrated that the I507-ATC→ATT SCC alters ΔF508 CFTR mRNA structure and translation dynamics. By comparing the biochemical and functional properties of the I507-ATT and I507-ATC ΔF508 CFTR, we establish that the I507-ATC→ATT SCC contributes to the cotranslational misfolding, ERAD, and to the functional defects associated with ΔF508 CFTR. We demonstrate that the I507-ATC ΔF508 CFTR is less susceptible to the ER quality-control machinery during translation than the I507-ATT, although 27°C correction is necessary for sufficient cell-surface expression. Whole-cell patch-clamp recordings indicate sustained, thermally stable cAMP-activated Cl(-) transport through I507-ATC and unstable function of the I507-ATT ΔF508 CFTR. Single-channel recordings reveal improved gating properties of the I507-ATC compared to I507-ATT ΔF508 CFTR (NPo=0.45±0.037 vs. NPo=0.09±0.002; P<0.001). Our results signify the role of the I507-ATC→ATT SCC in the ΔF508 CFTR defects and support the importance of synonymous codon choices in determining the function of gene products.
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Affiliation(s)
- Ahmed Lazrak
- 2Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Blvd., MCLM 350A, Birmingham, AL 35294, USA.
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Apaja PM, Foo B, Okiyoneda T, Valinsky WC, Barriere H, Atanasiu R, Ficker E, Lukacs GL, Shrier A. Ubiquitination-dependent quality control of hERG K+ channel with acquired and inherited conformational defect at the plasma membrane. Mol Biol Cell 2013; 24:3787-804. [PMID: 24152733 PMCID: PMC3861077 DOI: 10.1091/mbc.e13-07-0417] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Membrane trafficking in concert with the peripheral quality control machinery plays a critical role in preserving plasma membrane (PM) protein homeostasis. Unfortunately, the peripheral quality control may also dispose of partially or transiently unfolded polypeptides and thereby contribute to the loss-of-expression phenotype of conformational diseases. Defective functional PM expression of the human ether-a-go-go-related gene (hERG) K(+) channel leads to the prolongation of the ventricular action potential that causes long QT syndrome 2 (LQT2), with increased propensity for arrhythmia and sudden cardiac arrest. LQT2 syndrome is attributed to channel biosynthetic processing defects due to mutation, drug-induced misfolding, or direct channel blockade. Here we provide evidence that a peripheral quality control mechanism can contribute to development of the LQT2 syndrome. We show that PM hERG structural and metabolic stability is compromised by the reduction of extracellular or intracellular K(+) concentration. Cardiac glycoside-induced intracellular K(+) depletion conformationally impairs the complex-glycosylated channel, which provokes chaperone- and C-terminal Hsp70-interacting protein-dependent polyubiquitination, accelerated internalization, and endosomal sorting complex required for transport-dependent lysosomal degradation. A similar mechanism contributes to the down-regulation of PM hERG harboring LQT2 missense mutations, with incomplete secretion defect. These results suggest that PM quality control plays a determining role in the loss-of-expression phenotype of hERG in certain hereditary and acquired LTQ2 syndromes.
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Affiliation(s)
- Pirjo M Apaja
- Department of Physiology and Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montréal, QC H3E 1Y6, Canada
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Positively correlated miRNA-mRNA regulatory networks in mouse frontal cortex during early stages of alcohol dependence. BMC Genomics 2013; 14:725. [PMID: 24148570 PMCID: PMC3924350 DOI: 10.1186/1471-2164-14-725] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 10/04/2013] [Indexed: 01/06/2023] Open
Abstract
Background Although the study of gene regulation via the action of specific microRNAs (miRNAs) has experienced a boom in recent years, the analysis of genome-wide interaction networks among miRNAs and respective targeted mRNAs has lagged behind. MicroRNAs simultaneously target many transcripts and fine-tune the expression of genes through cooperative/combinatorial targeting. Therefore, they have a large regulatory potential that could widely impact development and progression of diseases, as well as contribute unpredicted collateral effects due to their natural, pathophysiological, or treatment-induced modulation. We support the viewpoint that whole mirnome-transcriptome interaction analysis is required to better understand the mechanisms and potential consequences of miRNA regulation and/or deregulation in relevant biological models. In this study, we tested the hypotheses that ethanol consumption induces changes in miRNA-mRNA interaction networks in the mouse frontal cortex and that some of the changes observed in the mouse are equivalent to changes in similar brain regions from human alcoholics. Results miRNA-mRNA interaction networks responding to ethanol insult were identified by differential expression analysis and weighted gene coexpression network analysis (WGCNA). Important pathways (coexpressed modular networks detected by WGCNA) and hub genes central to the neuronal response to ethanol are highlighted, as well as key miRNAs that regulate these processes and therefore represent potential therapeutic targets for treating alcohol addiction. Importantly, we discovered a conserved signature of changing miRNAs between ethanol-treated mice and human alcoholics, which provides a valuable tool for future biomarker/diagnostic studies in humans. We report positively correlated miRNA-mRNA expression networks that suggest an adaptive, targeted miRNA response due to binge ethanol drinking. Conclusions This study provides new evidence for the role of miRNA regulation in brain homeostasis and sheds new light on current understanding of the development of alcohol dependence. To our knowledge this is the first report that activated expression of miRNAs correlates with activated expression of mRNAs rather than with mRNA downregulation in an in vivo model. We speculate that early activation of miRNAs designed to limit the effects of alcohol-induced genes may be an essential adaptive response during disease progression.
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Galietta LJV. Managing the underlying cause of cystic fibrosis: a future role for potentiators and correctors. Paediatr Drugs 2013; 15:393-402. [PMID: 23757197 DOI: 10.1007/s40272-013-0035-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Cystic fibrosis (CF), a severe genetic disease, is caused by mutations that alter the structure and function of CFTR, a plasma membrane channel permeable to chloride and bicarbonate. Defective anion transport in CF irreversibly damages the lungs, pancreas, liver, and other organs. CF mutations cause loss of CFTR function in multiple ways. In particular, class 3 mutations such as p.Gly551Asp strongly decrease the time spent by CFTR in the open state (gating defect). Instead, class 2 mutations impair the maturation of CFTR protein and its transport from the endoplasmic reticulum to the plasma membrane (trafficking defect). The deletion of phenylalanine 508 (p.Phe508del), the most frequent mutation among CF patients (70-90 %), destabilizes the CFTR protein, thus causing both a trafficking and a gating defect. These two defects can be overcome with drug-like molecules generically called correctors and potentiators, respectively. The potentiator Kalydeco™ (also known as Ivacaftor or VX-770), developed by Vertex Pharmaceuticals, has been recently approved by the US FDA and the European Medicines Agency (EMA) for the treatment of CF patients carrying at least one CFTR allele with the p.Gly551Asp mutation (2-5 % of all patients). In contrast, the corrector VX-809, which significantly improves p.Phe508del-CFTR trafficking in vitro, is still under study in clinical trials. Because of multiple defects caused by the p.Phe508del mutation, it is probable that rescue of the mutant protein will require combined treatment with correctors having different mechanisms of action. This review evaluates the status of experimental and clinical research in pharmacotherapy for the CF basic defect.
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Affiliation(s)
- Luis J V Galietta
- Laboratorio di Genetica Molecolare, Istituto Giannina Gaslini, Via Gerolamo Gaslini 5, 16147, Genova, Italy,
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Hanrahan JW, Sampson HM, Thomas DY. Novel pharmacological strategies to treat cystic fibrosis. Trends Pharmacol Sci 2013; 34:119-25. [PMID: 23380248 DOI: 10.1016/j.tips.2012.11.006] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 11/28/2012] [Accepted: 11/28/2012] [Indexed: 12/15/2022]
Abstract
Cystic fibrosis (CF) is a lethal disease caused by mutations in the CFTR gene. The most frequent mutation is deletion of a phenylalanine residue (ΔF508) that results in retention of the mutant, but otherwise functional, protein in the endoplasmic reticulum (ER). There have been recent advances in the identification of chemically diverse corrector compounds that allow ΔF508-CFTR protein to traffic from the ER to the plasma membrane. The most studied correctors fall into two categories, pharmacological chaperones that bind to the mutant protein and circumvent its recognition by the cellular protein quality control systems and proteostasis regulators that modify the cellular pathways responsible for protein quality control and trafficking. This review focuses on recent advances in the field, strategies for the development of drugs from corrector compounds for the treatment of CF, and identification of their targets and mechanism(s) of action.
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Affiliation(s)
- John W Hanrahan
- Cystic Fibrosis Translation Research centre, Faculty of Medicine, McGill University, 3655 Promenade Sir William Osler, Montreal H3G 1Y6, Quebec, Canada
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Comyn SA, Chan GT, Mayor T. False start: cotranslational protein ubiquitination and cytosolic protein quality control. J Proteomics 2013; 100:92-101. [PMID: 23954725 DOI: 10.1016/j.jprot.2013.08.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 08/02/2013] [Accepted: 08/04/2013] [Indexed: 12/18/2022]
Abstract
UNLABELLED Maintaining proteostasis is crucial to cells given the toxic potential of misfolded proteins and aggregates. To this end, cells rely on a number of quality control pathways that survey proteins both during, as well as after synthesis to prevent protein aggregation, promote protein folding, and to target terminally misfolded proteins for degradation. In eukaryotes, the ubiquitin proteasome system plays a critical role in protein quality control by selectively targeting proteins for degradation. Recent studies have added to our understanding of cytosolic protein quality control, particularly in the area of cotranslational protein ubiquitination, and suggest that overlap exists across co- and post-translational protein quality control networks. Here, we review recent advances made in the area of cytoplasmic protein quality control with an emphasis on the pathways involved in cotranslational degradation of eukaryotic cytosolic proteins. BIOLOGICAL SIGNIFICANCE Protein homeostasis, or proteostasis, encompasses the systems required by the cell for the generation and maintenance of the correct levels, conformational state, distribution, and degradation of its proteome. One of the challenges faced by the cell in maintaining proteostasis is the presence of misfolded proteins. Cells therefore have a number of protein quality control pathways to aid in folding or mediate the degradation of misfolded proteins. The ubiquitin proteasome system in particular plays a critical role in protein quality control by selectively targeting proteins for degradation. Nascent polypeptides can be ubiquitinated cotranslationally, however to what extent and how this is used by the cell as a quality control mechanism has, until recently, remained relatively unclear. The picture now emerging is one of two quality control networks: one that recognizes nascent polypeptides on stalled ribosomes and another that targets actively translating polypeptides that misfold, failing to attain their native conformation. These studies underscore the important balance between cotranslational protein folding and degradation in the maintenance of protein homeostasis. In this review we summarize recent advances made in the area of cytoplasmic protein quality control with an emphasis on pathways involved in cotranslational degradation of eukaryotic cytosolic proteins. This article is part of a Special Issue entitled: Can Proteomics Fill the Gap Between Genomics and Phenotypes?
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Affiliation(s)
- Sophie A Comyn
- Department of Biochemistry and Molecular Biology, Center for High-Throughput Biology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Gerard T Chan
- Department of Biochemistry and Molecular Biology, Center for High-Throughput Biology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Thibault Mayor
- Department of Biochemistry and Molecular Biology, Center for High-Throughput Biology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
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