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van der Sluijs P, Hoelen H, Schmidt A, Braakman I. The Folding Pathway of ABC Transporter CFTR: Effective and Robust. J Mol Biol 2024; 436:168591. [PMID: 38677493 DOI: 10.1016/j.jmb.2024.168591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Revised: 04/16/2024] [Accepted: 04/23/2024] [Indexed: 04/29/2024]
Abstract
De novo protein folding into a native three-dimensional structure is indispensable for biological function, is instructed by its amino acid sequence, and occurs along a vectorial trajectory. The human proteome contains thousands of membrane-spanning proteins, whose biosynthesis begins on endoplasmic reticulum-associated ribosomes. Nearly half of all membrane proteins traverse the membrane more than once, including therapeutically important protein families such as solute carriers, G-protein-coupled receptors, and ABC transporters. These mediate a variety of functions like signal transduction and solute transport and are often of vital importance for cell function and tissue homeostasis. Missense mutations in multispan membrane proteins can lead to misfolding and cause disease; an example is the ABC transporter Cystic Fibrosis Transmembrane Conductance Regulator (CFTR). Even though our understanding of multispan membrane-protein folding still is rather rudimental, the cumulative knowledge of 20 years of basic research on CFTR folding has led to development of drugs that modulate the misfolded protein. This has provided the prospect of a life without CF to the vast majority of patients. In this review we describe our understanding of the folding pathway of CFTR in cells, which is modular and tolerates many defects, making it effective and robust. We address how modulator drugs affect folding and function of CFTR, and distinguish protein stability from its folding process. Since the domain architecture of (mammalian) ABC transporters are highly conserved, we anticipate that the insights we discuss here for folding of CFTR may lay the groundwork for understanding the general rules of ABC-transporter folding.
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Affiliation(s)
- Peter van der Sluijs
- Cellular Protein Chemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, 3584 CH Utrecht, the Netherlands.
| | - Hanneke Hoelen
- Cellular Protein Chemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, 3584 CH Utrecht, the Netherlands; Present address: GenDx, Yalelaan 48, 3584 CM Utrecht, The Netherlands
| | - Andre Schmidt
- Cellular Protein Chemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, 3584 CH Utrecht, the Netherlands; 3D-Pharmxchange, Tilburg, the Netherlands
| | - Ineke Braakman
- Cellular Protein Chemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, 3584 CH Utrecht, the Netherlands
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2
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Lan PD, Nissley DA, Sitarik I, Vu QV, Jiang Y, To P, Xia Y, Fried SD, Li MS, O'Brien EP. Synonymous Mutations Can Alter Protein Dimerization Through Localized Interface Misfolding Involving Self-entanglements. J Mol Biol 2024; 436:168487. [PMID: 38341172 DOI: 10.1016/j.jmb.2024.168487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 01/10/2024] [Accepted: 02/06/2024] [Indexed: 02/12/2024]
Abstract
Synonymous mutations in messenger RNAs (mRNAs) can reduce protein-protein binding substantially without changing the protein's amino acid sequence. Here, we use coarse-grain simulations of protein synthesis, post-translational dynamics, and dimerization to understand how synonymous mutations can influence the dimerization of two E. coli homodimers, oligoribonuclease and ribonuclease T. We synthesize each protein from its wildtype, fastest- and slowest-translating synonymous mRNAs in silico and calculate the ensemble-averaged interaction energy between the resulting dimers. We find synonymous mutations alter oligoribonuclease's dimer properties. Relative to wildtype, the dimer interaction energy becomes 4% and 10% stronger, respectively, when translated from its fastest- and slowest-translating mRNAs. Ribonuclease T dimerization, however, is insensitive to synonymous mutations. The structural and kinetic origin of these changes are misfolded states containing non-covalent lasso-entanglements, many of which structurally perturb the dimer interface, and whose probability of occurrence depends on translation speed. These entangled states are kinetic traps that persist for long time scales. Entanglements cause altered dimerization energies for oligoribonuclease, as there is a large association (odds ratio: 52) between the co-occurrence of non-native self-entanglements and weak-binding dimer conformations. Simulated at all-atom resolution, these entangled structures persist for long timescales, indicating the conclusions are independent of model resolution. Finally, we show that regions of the protein we predict to have changes in entanglement are also structurally perturbed during refolding, as detected by limited-proteolysis mass spectrometry. Thus, non-native changes in entanglement at dimer interfaces is a mechanism through which oligomer structure and stability can be altered.
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Affiliation(s)
- Pham Dang Lan
- Institute for Computational Sciences and Technology, Ho Chi Minh City, Viet Nam; Faculty of Physics and Engineering Physics, VNUHCM-University of Science, 227, Nguyen Van Cu Street, District 5, Ho Chi Minh City, Viet Nam
| | - Daniel Allen Nissley
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA
| | - Ian Sitarik
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA
| | - Quyen V Vu
- Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw, Poland
| | - Yang Jiang
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA
| | - Philip To
- Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Yingzi Xia
- Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Stephen D Fried
- Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA; Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Mai Suan Li
- Institute for Computational Sciences and Technology, Ho Chi Minh City, Viet Nam; Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw, Poland
| | - Edward P O'Brien
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA; Bioinformatics and Genomics Graduate Program, The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA; Institute for Computational and Data Sciences, Pennsylvania State University, University Park, PA 16802, USA.
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3
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Farinha CM, Santos L, Ferreira JF. Cell type-specific regulation of CFTR trafficking-on the verge of progress. Front Cell Dev Biol 2024; 12:1338892. [PMID: 38505263 PMCID: PMC10949533 DOI: 10.3389/fcell.2024.1338892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Accepted: 02/21/2024] [Indexed: 03/21/2024] Open
Abstract
Trafficking of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein is a complex process that starts with its biosynthesis and folding in the endoplasmic reticulum. Exit from the endoplasmic reticulum (ER) is coupled with the acquisition of a compact structure that can be processed and traffic through the secretory pathway. Once reaching its final destination-the plasma membrane, CFTR stability is regulated through interaction with multiple protein partners that are involved in its post-translation modification, connecting the channel to several signaling pathways. The complexity of the process is further boosted when analyzed in the context of the airway epithelium. Recent advances have characterized in detail the different cell types that compose the surface epithelium and shifted the paradigm on which cells express CFTR and on their individual and combined contribution to the total expression (and function) of this chloride/bicarbonate channel. Here we review CFTR trafficking and its relationship with the knowledge on the different cell types of the airway epithelia. We explore the crosstalk between these two areas and discuss what is still to be clarified and how this can be used to develop more targeted therapies for CF.
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Affiliation(s)
- Carlos M. Farinha
- Faculty of Sciences, BioISI—Biosystems and Integrative Sciences Institute, University of Lisboa, Lisboa, Portugal
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Marchesin V, Monnier L, Blattmann P, Chevillard F, Kuntz C, Forny C, Kamper J, Studer R, Bossu A, Ertel EA, Nayler O, Brotschi C, Williams JT, Gatfield J. A uniquely efficacious type of CFTR corrector with complementary mode of action. SCIENCE ADVANCES 2024; 10:eadk1814. [PMID: 38427726 DOI: 10.1126/sciadv.adk1814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 01/26/2024] [Indexed: 03/03/2024]
Abstract
Three distinct pharmacological corrector types (I, II, III) with different binding sites and additive behavior only partially rescue the F508del-cystic fibrosis transmembrane conductance regulator (CFTR) folding and trafficking defect observed in cystic fibrosis. We describe uniquely effective, macrocyclic CFTR correctors that were additive to the known corrector types, exerting a complementary "type IV" corrector mechanism. Macrocycles achieved wild-type-like folding efficiency of F508del-CFTR at the endoplasmic reticulum and normalized CFTR currents in reconstituted patient-derived bronchial epithelium. Using photo-activatable macrocycles, docking studies and site-directed mutagenesis a highly probable binding site and pose for type IV correctors was identified in a cavity between lasso helix-1 (Lh1) and transmembrane helix-1 of membrane spanning domain (MSD)-1, distinct from the known corrector binding sites. Since only F508del-CFTR fragments spanning from Lh1 until MSD2 responded to type IV correctors, these likely promote cotranslational assembly of Lh1, MSD1, and MSD2. Previously corrector-resistant CFTR folding mutants were also robustly rescued, suggesting substantial therapeutic potential for type IV correctors.
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Affiliation(s)
| | - Lucile Monnier
- Idorsia Pharmaceuticals Ltd., 4123 Allschwil, Switzerland
| | | | | | | | - Camille Forny
- Idorsia Pharmaceuticals Ltd., 4123 Allschwil, Switzerland
| | - Judith Kamper
- Idorsia Pharmaceuticals Ltd., 4123 Allschwil, Switzerland
| | - Rolf Studer
- Idorsia Pharmaceuticals Ltd., 4123 Allschwil, Switzerland
| | | | - Eric A Ertel
- Idorsia Pharmaceuticals Ltd., 4123 Allschwil, Switzerland
| | - Oliver Nayler
- Idorsia Pharmaceuticals Ltd., 4123 Allschwil, Switzerland
| | | | | | - John Gatfield
- Idorsia Pharmaceuticals Ltd., 4123 Allschwil, Switzerland
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Kleizen B, de Mattos E, Papaioannou O, Monti M, Tartaglia GG, van der Sluijs P, Braakman I. Transmembrane Helices 7 and 8 Confer Aggregation Sensitivity to the Cystic Fibrosis Transmembrane Conductance Regulator. Int J Mol Sci 2023; 24:15741. [PMID: 37958724 PMCID: PMC10648718 DOI: 10.3390/ijms242115741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 10/18/2023] [Accepted: 10/19/2023] [Indexed: 11/15/2023] Open
Abstract
The Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is a large multi-spanning membrane protein that is susceptible to misfolding and aggregation. We have identified here the region responsible for this instability. Temperature-induced aggregation of C-terminally truncated versions of CFTR demonstrated that all truncations up to the second transmembrane domain (TMD2), including the R region, largely resisted aggregation. Limited proteolysis identified a folded structure that was prone to aggregation and consisted of TMD2 and at least part of the Regulatory Region R. Only when both TM7 (TransMembrane helix 7) and TM8 were present, TMD2 fragments became as aggregation-sensitive as wild-type CFTR, in line with increased thermo-instability of late CFTR nascent chains and in silico prediction of aggregation propensity. In accord, isolated TMD2 was degraded faster in cells than isolated TMD1. We conclude that TMD2 extended at its N-terminus with part of the R region forms a protease-resistant structure that induces heat instability in CFTR and may be responsible for its limited intracellular stability.
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Affiliation(s)
- Bertrand Kleizen
- Cellular Protein Chemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, 3584 CH Utrecht, The Netherlands; (B.K.); (E.d.M.); (O.P.); (P.v.d.S.)
| | - Eduardo de Mattos
- Cellular Protein Chemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, 3584 CH Utrecht, The Netherlands; (B.K.); (E.d.M.); (O.P.); (P.v.d.S.)
| | - Olga Papaioannou
- Cellular Protein Chemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, 3584 CH Utrecht, The Netherlands; (B.K.); (E.d.M.); (O.P.); (P.v.d.S.)
| | - Michele Monti
- Center for Life Nano- & Neuro-Science, Fondazione Istituto Italiano di Tecnologia (IIT), 00161 Rome, Italy; (M.M.); (G.G.T.)
- Centre for Human Technologies (CHT), Istituto Italiano di Tecnologia (IIT), 16152 Genoa, Italy
| | - Gian Gaetano Tartaglia
- Center for Life Nano- & Neuro-Science, Fondazione Istituto Italiano di Tecnologia (IIT), 00161 Rome, Italy; (M.M.); (G.G.T.)
- Centre for Human Technologies (CHT), Istituto Italiano di Tecnologia (IIT), 16152 Genoa, Italy
| | - Peter van der Sluijs
- Cellular Protein Chemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, 3584 CH Utrecht, The Netherlands; (B.K.); (E.d.M.); (O.P.); (P.v.d.S.)
| | - Ineke Braakman
- Cellular Protein Chemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, 3584 CH Utrecht, The Netherlands; (B.K.); (E.d.M.); (O.P.); (P.v.d.S.)
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Stanke F, Pallenberg ST, Tamm S, Hedtfeld S, Eichhorn EM, Minso R, Hansen G, Welte T, Sauer-Heilborn A, Ringshausen FC, Junge S, Tümmler B, Dittrich AM. Changes in cystic fibrosis transmembrane conductance regulator protein expression prior to and during elexacaftor-tezacaftor-ivacaftor therapy. Front Pharmacol 2023; 14:1114584. [PMID: 36778025 PMCID: PMC9911415 DOI: 10.3389/fphar.2023.1114584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 01/16/2023] [Indexed: 01/28/2023] Open
Abstract
Background: Defects in expression, maturation or function of the epithelial membrane glycoprotein CFTR are causative for the progressive disease cystic fibrosis. Recently, molecular therapeutics that improve CFTR maturation and functional defects have been approved. We aimed to verify whether we could detect an improvement of CFTR protein expression and maturation by triple therapy with elexacaftor-tezacaftor-ivacaftor (ELX/TEZ/IVA). Methods: Rectal suction biopsies of 21 p.Phe508del homozygous or compound heterozygous CF patients obtained pre- and during treatment with ELX/TEZ/IVA were analyzed by CFTR Western blot that was optimized to distinguish CFTR glycoisoforms. Findings: CFTR western immunoblot analysis revealed that-compared to baseline-the levels of CFTR protein increased by at least twofold in eight out of 12 patients upon treatment with ELX/TEZ/IVA compared to baseline (p < 0.02). However, polydispersity of the mutant CFTR protein was lower than that of the fully glycosylated wild type CFTR Golgi isoform, indicating an incompletely glycosylated p.Phe508el CFTR protein isoform C* in patients with CF which persists after ELX/TEZ/IVA treatment. Interpretation: Treatment with ELX/TEZ/IVA increased protein expression by facilitating the posttranslational processing of mutant CFTR but apparently did not succeed in generating the polydisperse spectrum of N-linked oligosaccharides that is characteristic for the wild type CFTR band C glycoisoform. Our results caution that the lower amounts or immature glycosylation of the C* glycoisoform observed in patients' biomaterial might not translate to fully restored function of mutant CFTR necessary for long-term provision of clinical benefit.
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Affiliation(s)
- Frauke Stanke
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, Hannover, Germany,*Correspondence: Frauke Stanke,
| | - Sophia T. Pallenberg
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany
| | - Stephanie Tamm
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, Hannover, Germany
| | - Silke Hedtfeld
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany
| | - Ella M. Eichhorn
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany
| | - Rebecca Minso
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany
| | - Gesine Hansen
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, Hannover, Germany
| | - Tobias Welte
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, Hannover, Germany,Department of Respiratory Medicine, Hannover Medical School, Hannover, Germany
| | | | - Felix C. Ringshausen
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, Hannover, Germany,Department of Respiratory Medicine, Hannover Medical School, Hannover, Germany
| | - Sibylle Junge
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany
| | - Burkhard Tümmler
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, Hannover, Germany
| | - Anna-Maria Dittrich
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, Hannover, Germany
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7
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Pranke IM, Chevalier B, Premchandar A, Baatallah N, Tomaszewski KF, Bitam S, Tondelier D, Golec A, Stolk J, Lukacs GL, Hiemstra PS, Dadlez M, Lomas DA, Irving JA, Delaunay-Moisan A, van Anken E, Hinzpeter A, Sermet-Gaudelus I, Edelman A. Keratin 8 is a scaffolding and regulatory protein of ERAD complexes. Cell Mol Life Sci 2022; 79:503. [PMID: 36045259 DOI: 10.1007/s00018-022-04528-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 08/08/2022] [Accepted: 08/12/2022] [Indexed: 11/03/2022]
Abstract
Early recognition and enhanced degradation of misfolded proteins by the endoplasmic reticulum (ER) quality control and ER-associated degradation (ERAD) cause defective protein secretion and membrane targeting, as exemplified for Z-alpha-1-antitrypsin (Z-A1AT), responsible for alpha-1-antitrypsin deficiency (A1ATD) and F508del-CFTR (cystic fibrosis transmembrane conductance regulator) responsible for cystic fibrosis (CF). Prompted by our previous observation that decreasing Keratin 8 (K8) expression increased trafficking of F508del-CFTR to the plasma membrane, we investigated whether K8 impacts trafficking of soluble misfolded Z-A1AT protein. The subsequent goal of this study was to elucidate the mechanism underlying the K8-dependent regulation of protein trafficking, focusing on the ERAD pathway. The results show that diminishing K8 concentration in HeLa cells enhances secretion of both Z-A1AT and wild-type (WT) A1AT with a 13-fold and fourfold increase, respectively. K8 down-regulation triggers ER failure and cellular apoptosis when ER stress is jointly elicited by conditional expression of the µs heavy chains, as previously shown for Hrd1 knock-out. Simultaneous K8 silencing and Hrd1 knock-out did not show any synergistic effect, consistent with K8 acting in the Hrd1-governed ERAD step. Fractionation and co-immunoprecipitation experiments reveal that K8 is recruited to ERAD complexes containing Derlin2, Sel1 and Hrd1 proteins upon expression of Z/WT-A1AT and F508del-CFTR. Treatment of the cells with c407, a small molecule inhibiting K8 interaction, decreases K8 and Derlin2 recruitment to high-order ERAD complexes. This was associated with increased Z-A1AT secretion in both HeLa and Z-homozygous A1ATD patients' respiratory cells. Overall, we provide evidence that K8 acts as an ERAD modulator. It may play a scaffolding protein role for early-stage ERAD complexes, regulating Hrd1-governed retrotranslocation initiation/ubiquitination processes. Targeting K8-containing ERAD complexes is an attractive strategy for the pharmacotherapy of A1ATD.
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Affiliation(s)
- Iwona Maria Pranke
- Inserm, U1151, CNRS UMR 8253, Université de Paris, 160 rue de Vaugirard, 75015, Paris, France.
| | - Benoit Chevalier
- Inserm, U1151, CNRS UMR 8253, Université de Paris, 160 rue de Vaugirard, 75015, Paris, France
| | - Aiswarya Premchandar
- Laboratory of Mass Spectrometry, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02106, Warsaw, Poland
| | - Nesrine Baatallah
- Inserm, U1151, CNRS UMR 8253, Université de Paris, 160 rue de Vaugirard, 75015, Paris, France
| | - Kamil F Tomaszewski
- Inserm, U1151, CNRS UMR 8253, Université de Paris, 160 rue de Vaugirard, 75015, Paris, France
| | - Sara Bitam
- Inserm, U1151, CNRS UMR 8253, Université de Paris, 160 rue de Vaugirard, 75015, Paris, France
| | - Danielle Tondelier
- Inserm, U1151, CNRS UMR 8253, Université de Paris, 160 rue de Vaugirard, 75015, Paris, France
| | - Anita Golec
- Inserm, U1151, CNRS UMR 8253, Université de Paris, 160 rue de Vaugirard, 75015, Paris, France
| | - Jan Stolk
- Department of Pulmonology, Leiden University Medical Center, Leiden, The Netherlands
| | - Gergely L Lukacs
- Department of Physiology, McGill University, Montréal, QC, Canada.,Department of Biochemistry, McGill University, Montréal, QC, Canada
| | - Pieter S Hiemstra
- Department of Pulmonology, Leiden University Medical Center, Leiden, The Netherlands
| | - Michal Dadlez
- Laboratory of Mass Spectrometry, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02106, Warsaw, Poland
| | - David A Lomas
- UCL Respiratory and the Institute of Structural and Molecular Biology, University College London, London, WC1E 6JF, UK
| | - James A Irving
- UCL Respiratory and the Institute of Structural and Molecular Biology, University College London, London, WC1E 6JF, UK
| | - Agnes Delaunay-Moisan
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, France
| | - Eelco van Anken
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy
| | - Alexandre Hinzpeter
- Inserm, U1151, CNRS UMR 8253, Université de Paris, 160 rue de Vaugirard, 75015, Paris, France
| | - Isabelle Sermet-Gaudelus
- Inserm, U1151, CNRS UMR 8253, Université de Paris, 160 rue de Vaugirard, 75015, Paris, France.,Cystic Fibrosis Center, Hôpital Necker Enfants Malades, Assistance Publique Hôpitaux de Paris, Paris, France
| | - Aleksander Edelman
- Inserm, U1151, CNRS UMR 8253, Université de Paris, 160 rue de Vaugirard, 75015, Paris, France.
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8
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Wu Q, Henri YT, Yao R, Yu L, Zhang B, Wang Z, Ma X, Zhao G, Hou X. Opposite regulation of F508del-CFTR biogenesis by four poly-lysine ubiquitin chains In vitro. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2022; 1870:140792. [PMID: 35569794 DOI: 10.1016/j.bbapap.2022.140792] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Revised: 05/05/2022] [Accepted: 05/09/2022] [Indexed: 06/15/2023]
Abstract
As a misfolding protein, almost all of F508del-CFTR is degraded by the ubiquitin-proteasome system before its maturation, which results in no membrane expression of cystic fibrosis transmembrane conductance regulator (CFTR) and therefore, no chloride secretion across epithelial cells of cystic fibrosis (CF) patients. The conjugation of ubiquitin (Ub) chains to protein substrates is necessary for the proteasomal degradation of F508del-CFTR. Ubiquitin contains seven lysine (K) residues, all of which can be conjugated to one another, forming poly-ubiquitin chains on substrates, either by mixing together, or by only one type of lysine providing sorting signals for different pathways. Here, we report that four lysine-linked poly-Ub chains (LLPUCs) were involved in F508del-CFTR biogenesis: LLPUCs linked by K11 or K48 facilitated F508del-CFTR degradation, whereas the other two linked by K63 and K33 protected F508del-CFTR from degradation. LLPUC K11 is more potent for F508del-CFTR degradation than K48. F508del-CFTR utilizes four specific lysine-linked poly-Ub chains during its biogenesis for opposite destiny through different identification by proteasomal shuttle protein or receptors. These findings provide new insights into the CF pathogenesis and are expected to facilitate the development of therapies for this devastating disease.
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Affiliation(s)
- Qingtian Wu
- School of Basic Medicine, Jiamusi University, Jiamusi, Heilongjiang 154007, China
| | | | - Ruixue Yao
- School of Basic Medicine, Jiamusi University, Jiamusi, Heilongjiang 154007, China
| | - Lianpeng Yu
- School of Basic Medicine, Jiamusi University, Jiamusi, Heilongjiang 154007, China
| | - Bo Zhang
- School of Basic Medicine, Jiamusi University, Jiamusi, Heilongjiang 154007, China
| | - Zixin Wang
- School of Basic Medicine, Jiamusi University, Jiamusi, Heilongjiang 154007, China
| | - Xuemei Ma
- The First Affiliated Hospital, Jiamusi University, Jiamusi, Heilongjiang 154003, China
| | - Gang Zhao
- School of Stomatology, Jiamusi University, Jiamusi, Heilongjiang 154002, China
| | - Xia Hou
- School of Basic Medicine, Jiamusi University, Jiamusi, Heilongjiang 154007, China.
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9
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Prins S, Corradi V, Sheppard DN, Tieleman DP, Vergani P. Can two wrongs make a right? F508del-CFTR ion channel rescue by second-site mutations in its transmembrane domains. J Biol Chem 2022; 298:101615. [PMID: 35065958 PMCID: PMC8861112 DOI: 10.1016/j.jbc.2022.101615] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 01/13/2022] [Accepted: 01/17/2022] [Indexed: 11/20/2022] Open
Abstract
Deletion of phenylalanine 508 (F508del) in the cystic fibrosis transmembrane conductance regulator (CFTR) anion channel is the most common cause of cystic fibrosis. The F508 residue is located on nucleotide-binding domain 1 (NBD1) in contact with the cytosolic extensions of the transmembrane helices, in particular intracellular loop 4 (ICL4). To investigate how absence of F508 at this interface impacts the CFTR protein, we carried out a mutagenesis scan of ICL4 by introducing second-site mutations at 11 positions in cis with F508del. Using an image-based fluorescence assay, we measured how each mutation affected membrane proximity and ion-channel function. The scan strongly validated the effectiveness of R1070W at rescuing F508del defects. Molecular dynamics simulations highlighted two features characterizing the ICL4/NBD1 interface of F508del/R1070W-CFTR: flexibility, with frequent transient formation of interdomain hydrogen bonds, and loosely stacked aromatic sidechains (F1068, R1070W, and F1074, mimicking F1068, F508, and F1074 in WT CFTR). F508del-CFTR displayed a distorted aromatic stack, with F1068 displaced toward the space vacated by F508, while in F508del/R1070F-CFTR, which largely retained F508del defects, R1070F could not form hydrogen bonds and the interface was less flexible. Other ICL4 second-site mutations which partially rescued F508del-CFTR included F1068M and F1074M. Methionine side chains allow hydrophobic interactions without the steric rigidity of aromatic rings, possibly conferring flexibility to accommodate the absence of F508 and retain a dynamic interface. These studies highlight how both hydrophobic interactions and conformational flexibility might be important at the ICL4/NBD1 interface, suggesting possible structural underpinnings of F508del-induced dysfunction.
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Affiliation(s)
- Stella Prins
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Valentina Corradi
- Department of Biological Sciences, Centre for Molecular Simulation, University of Calgary, Calgary, Alberta, Canada
| | - David N Sheppard
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - D Peter Tieleman
- Department of Biological Sciences, Centre for Molecular Simulation, University of Calgary, Calgary, Alberta, Canada
| | - Paola Vergani
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK.
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10
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Rescue of Mutant CFTR Trafficking Defect by the Investigational Compound MCG1516A. Cells 2022; 11:cells11010136. [PMID: 35011698 PMCID: PMC8750248 DOI: 10.3390/cells11010136] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 12/20/2021] [Accepted: 12/22/2021] [Indexed: 01/27/2023] Open
Abstract
Although some therapeutic progress has been achieved in developing small molecules that correct F508del-CFTR defects, the mechanism of action (MoA) of these compounds remain poorly elucidated. Here, we investigated the effects and MoA of MCG1516A, a newly developed F508del-CFTR corrector. MCG1516A effects on wild-type (WT) and F508del-CFTR were assessed by immunofluorescence microscopy, and biochemical and functional assays both in cell lines and in intestinal organoids. To shed light on the MoA of MCG1516A, we evaluated its additivity to the FDA-approved corrector VX-661, low temperature, genetic revertants of F508del-CFTR (G550E, R1070W, and 4RK), and the traffic-null variant DD/AA. Finally, we explored the ability of MCG1516A to rescue trafficking and function of other CF-causing mutations. We found that MCG1516A rescues F508del-CFTR with additive effects to VX-661. A similar behavior was observed for WT-CFTR. Under low temperature incubation, F508del-CFTR demonstrated an additivity in processing and function with VX-661, but not with MCG1516A. In contrast, both compounds promoted additional effects to low temperature to WT-CFTR. MCG1516A demonstrated additivity to genetic revertant R1070W, while VX-661 was additive to G550E and 4RK. Nevertheless, none of these compounds rescued DD/AA trafficking. Both MCG1516A and VX-661 rescued CFTR processing of L206W- and R334W-CFTR with greater effects when these compounds were combined. In summary, the absence of additivity of MCG1516A to genetic revertant G550E suggests a putative binding site for this compound on NBD1:NBD2 interface. Therefore, a combination of MCG1516A with compounds able to rescue DD/AA traffic, or mimicking the actions of revertant R1070W (e.g., VX-661), could enhance correction of F508del-CFTR defects.
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11
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SLC26A9 is selected for endoplasmic reticulum associated degradation (ERAD) via Hsp70-dependent targeting of the soluble STAS domain. Biochem J 2021; 478:4203-4220. [PMID: 34821356 PMCID: PMC8826537 DOI: 10.1042/bcj20210644] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 11/23/2021] [Accepted: 11/24/2021] [Indexed: 12/24/2022]
Abstract
SLC26A9, a member of the solute carrier protein family, transports chloride ions across various epithelia. SLC26A9 also associates with other ion channels and transporters linked to human health, and in some cases these heterotypic interactions are essential to support the biogenesis of both proteins. Therefore, understanding how this complex membrane protein is initially folded might provide new therapeutic strategies to overcome deficits in the function of SLC26A9 partners, one of which is associated with Cystic Fibrosis. To this end, we developed a novel yeast expression system for SLC26A9. This facile system has been used extensively with other ion channels and transporters to screen for factors that oversee protein folding checkpoints. As commonly observed for other channels and transporters, we first noted that a substantial fraction of SLC26A9 is targeted for endoplasmic reticulum associated degradation (ERAD), which destroys folding-compromised proteins in the early secretory pathway. We next discovered that ERAD selection requires the Hsp70 chaperone, which can play a vital role in ERAD substrate selection. We then created SLC26A9 mutants and found that the transmembrane-rich domain of SLC26A9 was quite stable, whereas the soluble cytosolic STAS domain was responsible for Hsp70-dependent ERAD. To support data obtained in the yeast model, we were able to recapitulate Hsp70-facilitated ERAD of the STAS domain in human tissue culture cells. These results indicate that a critical barrier to nascent membrane protein folding can reside within a specific soluble domain, one that is monitored by components associated with the ERAD machinery.
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12
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Bardin E, Pastor A, Semeraro M, Golec A, Hayes K, Chevalier B, Berhal F, Prestat G, Hinzpeter A, Gravier-Pelletier C, Pranke I, Sermet-Gaudelus I. Modulators of CFTR. Updates on clinical development and future directions. Eur J Med Chem 2021; 213:113195. [PMID: 33524685 DOI: 10.1016/j.ejmech.2021.113195] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 01/08/2021] [Accepted: 01/11/2021] [Indexed: 12/19/2022]
Abstract
Cystic fibrosis (CF) is the most frequent life-limiting autosomal recessive disorder in the Caucasian population. It is due to mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene. Current symptomatic CF therapies, which treat the downstream consequences of CFTR mutations, have increased survival. Better knowledge of the CFTR protein has enabled pharmacologic therapy aiming to restore mutated CFTR expression and function. These CFTR "modulators" have revolutionised the CF therapeutic landscape, with the potential to transform prognosis for a considerable number of patients. This review provides a brief summary of their mechanism of action and presents a thorough review of the results obtained from clinical trials of CFTR modulators.
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Affiliation(s)
| | - Alexandra Pastor
- LCBPT, UMR CNRS 8601, Paris, France; Université de Paris, Paris, France
| | - Michaela Semeraro
- Centre d'Investigation Clinique, Unité de Recherche Clinique-CIC P1419, Hôpital Necker Enfants Malades, Université de Paris, Paris, France
| | - Anita Golec
- Institut Necker Enfants Malades. INSERM U1151, Paris, France
| | - Kate Hayes
- Clinical Trial Network, European Cystic Fibrosis Society, Belfast, Ireland
| | | | - Farouk Berhal
- LCBPT, UMR CNRS 8601, Paris, France; Université de Paris, Paris, France
| | - Guillaume Prestat
- LCBPT, UMR CNRS 8601, Paris, France; Université de Paris, Paris, France
| | | | | | - Iwona Pranke
- Institut Necker Enfants Malades. INSERM U1151, Paris, France
| | - Isabelle Sermet-Gaudelus
- Institut Necker Enfants Malades. INSERM U1151, Paris, France; Université de Paris, Paris, France; Clinical Trial Network, European Cystic Fibrosis Society, Belfast, Ireland; Centre de Référence Maladies Rares, Mucoviscidose et Maladies de CFTR, Hôpital Necker Enfants Malades, Paris, France; European Respiratory Network Lung, Paris, France.
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13
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Modulation of cAMP metabolism for CFTR potentiation in human airway epithelial cells. Sci Rep 2021; 11:904. [PMID: 33441643 PMCID: PMC7807051 DOI: 10.1038/s41598-020-79555-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 12/07/2020] [Indexed: 12/02/2022] Open
Abstract
Cystic fibrosis (CF) is a genetic disease characterized by CF transmembrane regulator (CFTR) dysfunction. With over 2000 CFTR variants identified, in addition to known patient to patient variability, there is a need for personalized treatment. The discovery of CFTR modulators has shown efficacy in certain CF populations, however there are still CF populations without valid therapeutic options. With evidence suggesting that single drug therapeutics are insufficient for optimal management of CF disease, there has been an increased pursuit of combinatorial therapies. Our aim was to test cyclic AMP (cAMP) modulation, through ATP Binding Cassette Transporter C4 (ABCC4) and phosphodiesterase-4 (PDE-4) inhibition, as a potential add-on therapeutic to a clinically approved CFTR modulator, VX-770, as a method for increasing CFTR activity. Human airway epithelial cells (Calu-3) were used to test the efficacy of cAMP modulation by ABCC4 and PDE-4 inhibition through a series of concentration–response studies. Our results showed that cAMP modulation, in combination with VX-770, led to an increase in CFTR activity via an increase in sensitivity when compared to treatment of VX-770 alone. Our study suggests that cAMP modulation has potential to be pursued as an add-on therapy for the optimal management of CF disease.
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Poothong J, Jang I, Kaufman RJ. Defects in Protein Folding and/or Quality Control Cause Protein Aggregation in the Endoplasmic Reticulum. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2021; 59:115-143. [PMID: 34050864 DOI: 10.1007/978-3-030-67696-4_6] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Protein aggregation is now a common hallmark of numerous human diseases, most of which involve cytosolic aggregates including Aβ (AD) and ⍺-synuclein (PD) in Alzheimer's disease and Parkinson's disease. However, it is also evident that protein aggregation can also occur in the lumen of the endoplasmic reticulum (ER) that leads to specific diseases due to loss of protein function or detrimental effects on the host cell, the former is inherited in a recessive manner where the latter are dominantly inherited. However, the mechanisms of protein aggregation, disaggregation and degradation in the ER are not well understood. Here we provide an overview of factors that cause protein aggregation in the ER and how the ER handles aggregated proteins. Protein aggregation in the ER can result from intrinsic properties of the protein (hydrophobic residues in the ER), oxidative stress or nutrient depletion. The ER has quality control mechanisms [chaperone functions, ER-associated protein degradation (ERAD) and autophagy] to ensure only correctly folded proteins exit the ER and enter the cis-Golgi compartment. Perturbation of protein folding in the ER activates the unfolded protein response (UPR) that evolved to increase ER protein folding capacity and efficiency and degrade misfolded proteins. Accumulation of misfolded proteins in the ER to a level that exceeds the ER-chaperone folding capacity is a major factor that exacerbates protein aggregation. The most significant ER resident protein that prevents protein aggregation in the ER is the heat shock protein 70 (HSP70) homologue, BiP/GRP78, which is a peptide-dependent ATPase that binds unfolded/misfolded proteins and releases them upon ATP binding. Since exogenous factors can also reduce protein misfolding and aggregation in the ER, such as chemical chaperones and antioxidants, these treatments have potential therapeutic benefit for ER protein aggregation-associated diseases.
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Affiliation(s)
- Juthakorn Poothong
- Degenerative Diseases Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Insook Jang
- Degenerative Diseases Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Randal J Kaufman
- Degenerative Diseases Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA.
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15
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Gopallawa I, Lee RJ. Targeting the phosphoinositide-3-kinase/protein kinase B pathway in airway innate immunity. World J Biol Chem 2020; 11:30-51. [PMID: 33024516 PMCID: PMC7520643 DOI: 10.4331/wjbc.v11.i2.30] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/24/2020] [Accepted: 08/26/2020] [Indexed: 02/06/2023] Open
Abstract
The airway innate immune system maintains the first line of defense against respiratory infections. The airway epithelium and associated immune cells protect the respiratory system from inhaled foreign organisms. These cells sense pathogens via activation of receptors like toll-like receptors and taste family 2 receptors (T2Rs) and respond by producing antimicrobials, inflammatory cytokines, and chemokines. Coordinated regulation of fluid secretion and ciliary beating facilitates clearance of pathogens via mucociliary transport. Airway cells also secrete antimicrobial peptides and radicals to directly kill microorganisms and inactivate viruses. The phosphoinositide-3-kinase/protein kinase B (Akt) kinase pathway regulates multiple cellular targets that modulate cell survival and proliferation. Akt also regulates proteins involved in innate immune pathways. Akt phosphorylates endothelial nitric oxide synthase (eNOS) enzymes expressed in airway epithelial cells. Activation of eNOS can have anti-inflammatory, anti-bacterial, and anti-viral roles. Moreover, Akt can increase the activity of the transcription factor nuclear factor erythroid 2 related factor-2 that protects cells from oxidative stress and may limit inflammation. In this review, we summarize the recent findings of non-cancerous functions of Akt signaling in airway innate host defense mechanisms, including an overview of several known downstream targets of Akt involved in innate immunity.
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Affiliation(s)
- Indiwari Gopallawa
- Department of Otorhinolaryngology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Robert J Lee
- Department of Otorhinolaryngology and Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
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16
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Turton KB, Ingram RJ, Valvano MA. Macrophage dysfunction in cystic fibrosis: Nature or nurture? J Leukoc Biol 2020; 109:573-582. [PMID: 32678926 DOI: 10.1002/jlb.4ru0620-245r] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 06/03/2020] [Accepted: 06/05/2020] [Indexed: 12/12/2022] Open
Abstract
Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) affect the homeostasis of chloride flux by epithelial cells. This has deleterious consequences, especially in respiratory epithelia, where the defect results in mucus accumulation distinctive of cystic fibrosis. CFTR is, however, also expressed in phagocytic cells, like macrophages. Immune cells are highly sensitive to conditioning by their environment; thus, CFTR dysfunction in epithelia influences macrophages by affecting the lung milieu, but the mutations also appear to be directly consequential for intrinsic macrophage functions. Particular mutations can alter CFTR's folding, traffic of the protein to the membrane and function. As such, understanding the intrinsic effects of CFTR mutation requires distinguishing the secondary effects of misfolded CFTR on cell stress pathways from the primary defect of CFTR dysfunction/absence. Investigations into CFTR's role in macrophages have exploited various models, each with their own advantages and limitations. This review summarizes these methodologic approaches, discussing their physiological correspondence and highlighting key findings. The controversy surrounding CFTR-dependent acidification is used as a case study to highlight difficulties in commensurability across model systems. Recent work in macrophage biology, including polarization and host-pathogen interaction studies, brought into the context of CFTR research, offers potential explanations for observed discrepancies between studies. Moreover, the rapid advancement of novel gene editing technologies and new macrophage model systems makes this assessment of the field's models and methodologies timely.
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Affiliation(s)
- Keren B Turton
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
| | - Rebecca J Ingram
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
| | - Miguel A Valvano
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
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17
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Regulation of CFTR Biogenesis by the Proteostatic Network and Pharmacological Modulators. Int J Mol Sci 2020; 21:ijms21020452. [PMID: 31936842 PMCID: PMC7013518 DOI: 10.3390/ijms21020452] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Revised: 01/06/2020] [Accepted: 01/08/2020] [Indexed: 12/14/2022] Open
Abstract
Cystic fibrosis (CF) is the most common lethal inherited disease among Caucasians in North America and a significant portion of Europe. The disease arises from one of many mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator, or CFTR. The most common disease-associated allele, F508del, along with several other mutations affect the folding, transport, and stability of CFTR as it transits from the endoplasmic reticulum (ER) to the plasma membrane, where it functions primarily as a chloride channel. Early data demonstrated that F508del CFTR is selected for ER associated degradation (ERAD), a pathway in which misfolded proteins are recognized by ER-associated molecular chaperones, ubiquitinated, and delivered to the proteasome for degradation. Later studies showed that F508del CFTR that is rescued from ERAD and folds can alternatively be selected for enhanced endocytosis and lysosomal degradation. A number of other disease-causing mutations in CFTR also undergo these events. Fortunately, pharmacological modulators of CFTR biogenesis can repair CFTR, permitting its folding, escape from ERAD, and function at the cell surface. In this article, we review the many cellular checkpoints that monitor CFTR biogenesis, discuss the emergence of effective treatments for CF, and highlight future areas of research on the proteostatic control of CFTR.
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18
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Huang Y, Arora K, Mun KS, Yang F, Moon C, Yarlagadda S, Jegga A, Weaver T, Naren AP. Targeting DNAJB9, a novel ER luminal co-chaperone, to rescue ΔF508-CFTR. Sci Rep 2019; 9:9808. [PMID: 31285458 PMCID: PMC6614449 DOI: 10.1038/s41598-019-46161-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 06/19/2019] [Indexed: 01/30/2023] Open
Abstract
The molecular mechanism of Endoplasmic Reticulum-associated degradation (ERAD) of Cystic fibrosis transmembrane-conductance regulator (CFTR) is largely unknown. Particularly, it is unknown what ER luminal factor(s) are involved in ERAD. Herein, we used ProtoArray to identify an ER luminal co-chaperone, DNAJB9, which can directly interact with CFTR. For both WT- and ΔF508 (deletion of phenylalanine at position 508, the most common CF-causing mutant)-CFTR, knockdown of DNAJB9 by siRNA increased their expression levels on the cell surface and, consequently, upregulated their function. Furthermore, genetic ablation of DNAJB9 in WT mice increased CFTR expression and enhanced CFTR-dependent fluid secretion in enteroids. Importantly, DNAJB9 deficiency upregulated enteroids' fluid secretion in CF mice (homozygous for ΔF508), and silencing one allele of DNAJB9 is sufficient to rescue ΔF508-CFTR in vitro and in vivo, suggesting that DNAJB9 may be a rate-limiting factor in CFTR ERAD pathway. Our studies identified the first ER luminal co-chaperone involved in CFTR ERAD, and DNAJB9 could be a novel therapeutic target for CF.
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Affiliation(s)
- Yunjie Huang
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States
| | - Kavisha Arora
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States
| | - Kyu Shik Mun
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States
| | - Fanmuyi Yang
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States
| | - ChangSuk Moon
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States
| | - Sunitha Yarlagadda
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States
| | - Anil Jegga
- Division of Biomedical Informatics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States
| | - Timothy Weaver
- Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States
| | - Anjaparavanda P Naren
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States.
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19
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Pranke I, Golec A, Hinzpeter A, Edelman A, Sermet-Gaudelus I. Emerging Therapeutic Approaches for Cystic Fibrosis. From Gene Editing to Personalized Medicine. Front Pharmacol 2019; 10:121. [PMID: 30873022 PMCID: PMC6400831 DOI: 10.3389/fphar.2019.00121] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 01/31/2019] [Indexed: 12/13/2022] Open
Abstract
An improved understanding of the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) protein structure and the consequences of CFTR gene mutations have allowed the development of novel therapies targeting specific defects underlying CF. Some strategies are mutation specific and have already reached clinical development; some strategies include a read-through of the specific premature termination codons (read-through therapies, nonsense mediated decay pathway inhibitors for Class I mutations); correction of CFTR folding and trafficking to the apical plasma membrane (correctors for Class II mutations); and an increase in the function of CFTR channel (potentiators therapy for Class III mutations and any mutant with a residual function located at the membrane). Other therapies that are in preclinical development are not mutation specific and include gene therapy to edit the genome and stem cell therapy to repair the airway tissue. These strategies that are directed at the basic CF defects are now revolutionizing the treatment for patients and should positively impact their survival rates.
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Affiliation(s)
- Iwona Pranke
- INSERM U 1151, Institut Necker Enfants Malades, Université Paris Descartes, Paris, France
| | - Anita Golec
- INSERM U 1151, Institut Necker Enfants Malades, Université Paris Descartes, Paris, France
| | - Alexandre Hinzpeter
- INSERM U 1151, Institut Necker Enfants Malades, Université Paris Descartes, Paris, France
| | - Aleksander Edelman
- INSERM U 1151, Institut Necker Enfants Malades, Université Paris Descartes, Paris, France
| | - Isabelle Sermet-Gaudelus
- INSERM U 1151, Institut Necker Enfants Malades, Université Paris Descartes, Paris, France.,Centre de Référence Maladie Rare, Mucoviscidose et Maladies de CFTR, Paris, France.,Faculté de Médecine, Université Paris Descartes, Paris, France
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20
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Ferreira VFC, Oliveira BL, Santos JD, Correia JDG, Farinha CM, Mendes F. Targeting of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Protein with a Technetium-99m Imaging Probe. ChemMedChem 2018; 13:1469-1478. [PMID: 29864241 DOI: 10.1002/cmdc.201800187] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 05/18/2018] [Indexed: 12/28/2022]
Abstract
Cystic fibrosis (CF) is caused by mutations in the gene that encodes the CF transmembrane conductance regulator (CFTR) protein. The most common mutation, F508del, leads to almost total absence of CFTR at the plasma membrane, a defect potentially corrected via drug-based therapies. Herein, we report the first proof-of-principle study of a noninvasive imaging probe able to detect CFTR at the plasma membrane. We radiolabeled the CFTR inhibitor, CFTRinh -172a, with technetium-99m via a pyrazolyl-diamine chelating unit, yielding a novel 99m Tc(CO)3 complex. A non-radioactive surrogate showed that the structural modifications introduced in the inhibitor did not affect its activity. The radioactive complex was able to detect plasma membrane CFTR, shown by its significantly higher uptake in wild-type versus mutated cells. Furthermore, assessment of F508del CFTR pharmacological correction in human cells using the radioactive complex revealed differences in corrector versus control uptake, recapitulating the biochemical correction observed for the protein.
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Affiliation(s)
- Vera F C Ferreira
- C2TN-Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, 2695-066, Bobadela LRS, Portugal
| | - Bruno L Oliveira
- C2TN-Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, 2695-066, Bobadela LRS, Portugal
- Current address: Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, UK
| | - João D Santos
- BioISI-Biosystems and Integrative Sciences Institute, Faculty of Sciences, Universidade de Lisboa, Campo Grande C8, 1749-016, Lisboa, Portugal
| | - João D G Correia
- C2TN-Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, 2695-066, Bobadela LRS, Portugal
| | - Carlos M Farinha
- BioISI-Biosystems and Integrative Sciences Institute, Faculty of Sciences, Universidade de Lisboa, Campo Grande C8, 1749-016, Lisboa, Portugal
| | - Filipa Mendes
- C2TN-Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, 2695-066, Bobadela LRS, Portugal
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21
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Kaufman DR, Papillon J, Larose L, Iwawaki T, Cybulsky AV. Deletion of inositol-requiring enzyme-1α in podocytes disrupts glomerular capillary integrity and autophagy. Mol Biol Cell 2017; 28:1636-1651. [PMID: 28428258 PMCID: PMC5469607 DOI: 10.1091/mbc.e16-12-0828] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 04/10/2017] [Accepted: 04/14/2017] [Indexed: 12/02/2022] Open
Abstract
Inositol-requiring enzyme-1α (IRE1α) is an endoplasmic reticulum (ER)-transmembrane endoribonuclease kinase that plays an essential function in extraembryonic tissues during normal development and is activated during ER stress. To address the functional role of IRE1α in glomerular podocytes, we produced podocyte-specific IRE1α-deletion mice. In male mice, deletion of IRE1α in podocytes resulted in albuminuria beginning at 5 mo of age and worsening with time. Electron microscopy revealed focal podocyte foot-process effacement in 9-mo-old male IRE1α-deletion mice, as well as microvillous transformation of podocyte plasma membranes. Compared with control, glomerular cross-sectional and capillary lumenal areas were greater in deletion mice, and there was relative podocyte depletion. Levels of microtubule-associated protein 1A/1B-light chain 3 (LC3)-II expression and c-Jun N-terminal kinase-1 phosphorylation were decreased in IRE1α-deletion glomeruli, in keeping with reduced autophagy. Deletion of IRE1α exacerbated glomerular injury in anti-glomerular basement membrane nephritis. In cell culture, IRE1α dominant-negative mutants reduced the physiological (basal) accumulation of LC3B-II and the size of autophagic vacuoles but did not affect ER-associated degradation. Thus IRE1α is essential for maintaining podocyte and glomerular integrity as mice age and in glomerulonephritis. The mechanism is related, at least in part, to the maintenance of autophagy in podocytes.
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Affiliation(s)
- Daniel Robert Kaufman
- Department of Physiology, McGill University, and McGill University Health Centre Research Institute, Montreal, QC H4A 3J1, Canada
| | - Joan Papillon
- Department of Medicine, McGill University, and McGill University Health Centre Research Institute, Montreal, QC H4A 3J1, Canada
| | - Louise Larose
- Department of Medicine, McGill University, and McGill University Health Centre Research Institute, Montreal, QC H4A 3J1, Canada
| | - Takao Iwawaki
- Department of Life Science, Medical Research Institute, Kanazawa Medical University, Uchinada 920-0293, Japan
| | - Andrey V Cybulsky
- Department of Physiology, McGill University, and McGill University Health Centre Research Institute, Montreal, QC H4A 3J1, Canada
- Department of Medicine, McGill University, and McGill University Health Centre Research Institute, Montreal, QC H4A 3J1, Canada
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Kaabinejadian S, McMurtrey CP, Kim S, Jain R, Bardet W, Schafer FB, Davenport JL, Martin AD, Diamond MS, Weidanz JA, Hansen TH, Hildebrand WH. Immunodominant West Nile Virus T Cell Epitopes Are Fewer in Number and Fashionably Late. THE JOURNAL OF IMMUNOLOGY 2016; 196:4263-73. [PMID: 27183642 DOI: 10.4049/jimmunol.1501821] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 03/20/2016] [Indexed: 12/23/2022]
Abstract
Class I HLA molecules mark infected cells for immune targeting by presenting pathogen-encoded peptides on the cell surface. Characterization of viral peptides unique to infected cells is important for understanding CD8(+) T cell responses and for the development of T cell-based immunotherapies. Having previously reported a series of West Nile virus (WNV) epitopes that are naturally presented by HLA-A*02:01, in this study we generated TCR mimic (TCRm) mAbs to three of these peptide/HLA complexes-the immunodominant SVG9 (E protein), the subdominant SLF9 (NS4B protein), and the immunorecessive YTM9 (NS3 protein)-and used these TCRm mAbs to stain WNV-infected cell lines and primary APCs. TCRm staining of WNV-infected cells demonstrated that the immunorecessive YTM9 appeared several hours earlier and at 5- to 10-fold greater density than the more immunogenic SLF9 and SVG9 ligands, respectively. Moreover, staining following inhibition of the TAP demonstrated that all three viral ligands were presented in a TAP-dependent manner despite originating from different cellular compartments. To our knowledge, this study represents the first use of TCRm mAbs to define the kinetics and magnitude of HLA presentation for a series of epitopes encoded by one virus, and the results depict a pattern whereby individual epitopes differ considerably in abundance and availability. The observations that immunodominant ligands can be found at lower levels and at later time points after infection suggest that a reevaluation of the factors that combine to shape T cell reactivity may be warranted.
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Affiliation(s)
- Saghar Kaabinejadian
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104
| | - Curtis P McMurtrey
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104
| | - Sojung Kim
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO 63110
| | - Rinki Jain
- Center for Immunotherapeutic Research, Texas Tech University Health Sciences Center School of Pharmacy, Abilene, TX 79601; Department of Immunotherapeutics and Biotechnology, Texas Tech University Health Sciences Center School of Pharmacy, Abilene, TX 79601; Receptor Logic, Inc., Abilene, TX 79601
| | - Wilfried Bardet
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104
| | - Fredda B Schafer
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104
| | | | | | - Michael S Diamond
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO 63110; Department of Medicine, Washington University School of Medicine, St Louis, MO 63110; and Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO 63110
| | - Jon A Weidanz
- Center for Immunotherapeutic Research, Texas Tech University Health Sciences Center School of Pharmacy, Abilene, TX 79601; Department of Immunotherapeutics and Biotechnology, Texas Tech University Health Sciences Center School of Pharmacy, Abilene, TX 79601; Receptor Logic, Inc., Abilene, TX 79601
| | - Ted H Hansen
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO 63110
| | - William H Hildebrand
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104;
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Ahner A, Gong X, Frizzell RA. Divergent signaling via SUMO modification: potential for CFTR modulation. Am J Physiol Cell Physiol 2015; 310:C175-80. [PMID: 26582473 DOI: 10.1152/ajpcell.00124.2015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) is generally responsible for the cAMP/PKA regulated anion conductance at the apical membranes of secretory epithelial cells. Mutations in CFTR underlie cystic fibrosis (CF), in which the most common variant, F508del, causes protein misfolding and its proteasome-mediated degradation. A new pathway that contributes to mutant CFTR degradation is mediated by the small heat shock protein, Hsp27, which cooperates with Ubc9, the E2 enzyme for SUMOylation, to selectively conjugate mutant CFTR with SUMO-2/3. This SUMO paralog can form polychains, which are recognized by the ubiquitin E3 enzyme, RNF4, leading to CFTR ubiquitylation and recognition by the proteasome. We found also that F508del CFTR could be modified by SUMO-1, a paralog that does not support SUMO polychain formation. The use of different SUMO paralogs to modify and target a single substrate for divergent purposes is not uncommon. In this short review we discuss the possibility that conjugation with SUMO-1 could protect mutant CFTR from disposal by RNF4 and similar ubiquitin ligases. We hypothesize that such a pathway could contribute to therapeutic efforts to stabilize immature mutant CFTR and thereby enhance the action of therapeutics that correct CFTR trafficking to the apical membranes.
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Affiliation(s)
- Annette Ahner
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Xiaoyan Gong
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Raymond A Frizzell
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
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24
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Huang SS, Chen CL, Huang FW, Johnson FE, Huang JS. Ethanol Enhances TGF-β Activity by Recruiting TGF-β Receptors From Intracellular Vesicles/Lipid Rafts/Caveolae to Non-Lipid Raft Microdomains. J Cell Biochem 2015; 117:860-71. [PMID: 26419316 DOI: 10.1002/jcb.25389] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 09/28/2015] [Indexed: 12/16/2022]
Abstract
Regular consumption of moderate amounts of ethanol has important health benefits on atherosclerotic cardiovascular disease (ASCVD). Overindulgence can cause many diseases, particularly alcoholic liver disease (ALD). The mechanisms by which ethanol causes both beneficial and harmful effects on human health are poorly understood. Here we demonstrate that ethanol enhances TGF-β-stimulated luciferase activity with a maximum of 0.5-1% (v/v) in Mv1Lu cells stably expressing a luciferase reporter gene containing Smad2-dependent elements. In Mv1Lu cells, 0.5% ethanol increases the level of P-Smad2, a canonical TGF-β signaling sensor, by ∼ 2-3-fold. Ethanol (0.5%) increases cell-surface expression of the type II TGF-β receptor (TβR-II) by ∼ 2-3-fold from its intracellular pool, as determined by I(125) -TGF-β-cross-linking/Western blot analysis. Sucrose density gradient ultracentrifugation and indirect immunofluorescence staining analyses reveal that ethanol (0.5% and 1%) also displaces cell-surface TβR-I and TβR-II from lipid rafts/caveolae and facilitates translocation of these receptors to non-lipid raft microdomains where canonical signaling occurs. These results suggest that ethanol enhances canonical TGF-β signaling by increasing non-lipid raft microdomain localization of the TGF-β receptors. Since TGF-β plays a protective role in ASCVD but can also cause ALD, the TGF-β enhancer activity of ethanol at low and high doses appears to be responsible for both beneficial and harmful effects. Ethanol also disrupts the location of lipid raft/caveolae of other membrane proteins (e.g., neurotransmitter, growth factor/cytokine, and G protein-coupled receptors) which utilize lipid rafts/caveolae as signaling platforms. Displacement of these membrane proteins induced by ethanol may result in a variety of pathologies in nerve, heart and other tissues.
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Affiliation(s)
| | - Chun-Lin Chen
- Department of Biological Science, National Sun Yat-sen University, Kaohsiung, 804, Taiwan.,Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University and Academia Sinica, Kaohsiung, 804, Taiwan
| | - Franklin W Huang
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, 02115.,Harvard Medical School, Boston, Massachusetts, 02115
| | - Frank E Johnson
- Department of Surgery, Saint Louis University School of Medicine, St. Louis, Missouri, 63104
| | - Jung San Huang
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Doisy Research Center, St. Louis, Missouri, 63104
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25
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Bali V, Lazrak A, Guroji P, Fu L, Matalon S, Bebok Z. A synonymous codon change alters the drug sensitivity of ΔF508 cystic fibrosis transmembrane conductance regulator. FASEB J 2015; 30:201-13. [PMID: 26336913 DOI: 10.1096/fj.15-273714] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 08/31/2015] [Indexed: 11/11/2022]
Abstract
Synonymous mutations, such as I507-ATC→ATT, in deletion of Phe508 in cystic fibrosis transmembrane conductance regulator (ΔF508 CFTR), the most frequent disease-associated mutant of CFTR, may affect protein biogenesis, structure, and function and contribute to an altered disease phenotype. Small-molecule drugs are being developed to correct ΔF508 CFTR. To understand correction mechanisms and the consequences of synonymous mutations, we analyzed the effect of mechanistically distinct correctors, corrector 4a (C4) and lumacaftor (VX-809), on I507-ATT and I507-ATC ΔF508 CFTR biogenesis and function. C4 stabilized I507-ATT ΔF508 CFTR band B, but without considerable biochemical and functional correction. VX-809 biochemically corrected ∼10% of both of the variants, leading to stable, forskolin+3-isobutyl-1-methylxanthine (IBMX)-activated whole-cell currents in the presence of the corrector. Omitting VX-809 during whole-cell recordings led to a spontaneous decline of the currents, suggesting posttranslational stabilization by VX-809. Treatment of cells with the C4+VX-809 combination resulted in enhanced rescue and 2-fold higher forskolin+IBMX-activated currents of both I507-ATT and I507-ATC ΔF508 CFTR, compared with VX-809 treatment alone. The lack of an effect of C4 on I507-ATC ΔF508 CFTR, but its additive effect in combination with VX-809, implies that C4 acted on VX-809-modified I507-ATC ΔF508 CFTR. Our results suggest that binding of C4 and VX-809 to ΔF508 CFTR is conformation specific and provide evidence that synonymous mutations can alter the drug sensitivity of proteins.
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Affiliation(s)
- Vedrana Bali
- *Department of Cell, Developmental, and Integrative Biology, Department of Anesthesiology and Perioperative Medicine, The Lung Injury and Repair Research Center, and The Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Ahmed Lazrak
- *Department of Cell, Developmental, and Integrative Biology, Department of Anesthesiology and Perioperative Medicine, The Lung Injury and Repair Research Center, and The Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Purushotham Guroji
- *Department of Cell, Developmental, and Integrative Biology, Department of Anesthesiology and Perioperative Medicine, The Lung Injury and Repair Research Center, and The Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Lianwu Fu
- *Department of Cell, Developmental, and Integrative Biology, Department of Anesthesiology and Perioperative Medicine, The Lung Injury and Repair Research Center, and The Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Sadis Matalon
- *Department of Cell, Developmental, and Integrative Biology, Department of Anesthesiology and Perioperative Medicine, The Lung Injury and Repair Research Center, and The Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Zsuzsanna Bebok
- *Department of Cell, Developmental, and Integrative Biology, Department of Anesthesiology and Perioperative Medicine, The Lung Injury and Repair Research Center, and The Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
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Impact of Hybrid and Complex N-Glycans on Cell Surface Targeting of the Endogenous Chloride Cotransporter Slc12a2. Int J Cell Biol 2015; 2015:505294. [PMID: 26351455 PMCID: PMC4553341 DOI: 10.1155/2015/505294] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 06/29/2015] [Accepted: 07/07/2015] [Indexed: 11/21/2022] Open
Abstract
The Na+K+2Cl− cotransporter-1 (Slc12a2, NKCC1) is widely distributed and involved in cell volume/ion regulation. Functional NKCC1 locates in the plasma membrane of all cells studied, particularly in the basolateral membrane of most polarized cells. Although the mechanisms involved in plasma membrane sorting of NKCC1 are poorly understood, it is assumed that N-glycosylation is necessary. Here, we characterize expression, N-glycosylation, and distribution of NKCC1 in COS7 cells. We show that ~25% of NKCC1 is complex N-glycosylated whereas the rest of it corresponds to core/high-mannose and hybrid-type N-glycosylated forms. Further, ~10% of NKCC1 reaches the plasma membrane, mostly as core/high-mannose type, whereas ~90% of NKCC1 is distributed in defined intracellular compartments. In addition, inhibition of the first step of N-glycan biosynthesis with tunicamycin decreases total and plasma membrane located NKCC1 resulting in almost undetectable cotransport function. Moreover, inhibition of N-glycan maturation with swainsonine or kifunensine increased core/hybrid-type NKCC1 expression but eliminated plasma membrane complex N-glycosylated NKCC1 and transport function. Together, these results suggest that (i) NKCC1 is delivered to the plasma membrane of COS7 cells independently of its N-glycan nature, (ii) most of NKCC1 in the plasma membrane is core/hybrid-type N-glycosylated, and (iii) the minimal proportion of complex N-glycosylated NKCC1 is functionally active.
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27
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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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28
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Xu X, Balsiger R, Tyrrell J, Boyaka PN, Tarran R, Cormet-Boyaka E. Cigarette smoke exposure reveals a novel role for the MEK/ERK1/2 MAPK pathway in regulation of CFTR. Biochim Biophys Acta Gen Subj 2015; 1850:1224-32. [PMID: 25697727 DOI: 10.1016/j.bbagen.2015.02.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Revised: 01/19/2015] [Accepted: 02/06/2015] [Indexed: 12/22/2022]
Abstract
BACKGROUND Cystic fibrosis transmembrane conductance regulator plays a key role in maintenance of lung fluid homeostasis. Cigarette smoke decreases CFTR expression in the lung but neither the mechanisms leading to CFTR loss, nor potential ways to prevent its loss have been identified to date. METHODS The molecular mechanisms leading to down-regulation of CFTR by cigarette smoke were determined using pharmacologic inhibitors and silencing ribonucleic acids (RNAs). RESULTS Using human bronchial epithelial cells, here we show that cigarette smoke induces degradation of CFTR that is attenuated by lysosomal inhibitors, but not proteasome inhibitors. Cigarette smoke can activate multiple signaling pathways in airway epithelial cells, including the MEK/Erk1/2 MAPK (MEK: mitogen-activated protein kinase/ERK kinase Erk1/2: extracellular signal-regulated kinase 1/2 MAPK: Mitogen-activated protein kinase) pathway regulating cell survival. Interestingly, pharmacological inhibition of the MEK/Erk1/2 MAPK pathway prevented the loss of plasma membrane CFTR upon cigarette smoke exposure. Similarly, decreased expression of Erk1/2 using silencing RNAs prevented the suppression of CFTR protein by cigarette smoke. Conversely, specific inhibitors of the c-Jun N-terminal kinase (JNK) or p38 MAPK pathways had no effect on CFTR decrease after cigarette smoke exposure. In addition, inhibition of the MEK/Erk1/2 MAPK pathway prevented the reduction of the airway surface liquid observed upon cigarette smoke exposure of primary human airway epithelial cells. Finally, addition of the antioxidant N-acetylcysteine inhibited activation of Erk1/2 by cigarette smoke and precluded the cigarette smoke-induced decrease of CFTR. CONCLUSIONS These results show that the MEK/Erk1/2 MAPK pathway regulates plasma membrane CFTR in human airway cells. GENERAL SIGNIFICANCE The MEK/Erk1/2 MAPK pathway should be considered as a target for strategies to maintain/restore CFTR expression in the lung of smokers.
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Affiliation(s)
- Xiaohua Xu
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA
| | - Robert Balsiger
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA
| | - Jean Tyrrell
- Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina, Chapel Hill, NC, USA
| | - Prosper N Boyaka
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA
| | - Robert Tarran
- Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina, Chapel Hill, NC, USA
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29
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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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30
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Ramachandran S, Karp PH, Osterhaus SR, Jiang P, Wohlford-Lenane C, Lennox KA, Jacobi AM, Praekh K, Rose SD, Behlke MA, Xing Y, Welsh MJ, McCray PB. Post-transcriptional regulation of cystic fibrosis transmembrane conductance regulator expression and function by microRNAs. Am J Respir Cell Mol Biol 2014; 49:544-51. [PMID: 23646886 DOI: 10.1165/rcmb.2012-0430oc] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
MicroRNAs (miRNAs) are increasingly recognized as important posttranscriptional regulators of gene expression, and changes in their actions can contribute to disease states. Little is understood regarding miRNA functions in the airway epithelium under normal or diseased conditions. We profiled miRNA expression in well-differentiated primary cultures of human cystic fibrosis (CF) and non-CF airway epithelia, and discovered that miR-509-3p and miR-494 concentrations were increased in CF epithelia. Human non-CF airway epithelia, transfected with the mimics of miR-509-3p or miR-494, showed decreased cystic fibrosis transmembrane conductance regulator (CFTR) expression, whereas their respective anti-miRs exerted the opposite effect. Interestingly, the two miRNAs acted cooperatively in regulating CFTR expression. Upon infecting non-CF airway epithelial cells with Staphylococcus aureus, or upon stimulating them with the proinflammatory cytokines TNF-α or IL-1β, we observed an increased expression of both miRNAs and a concurrent decrease in CFTR expression and function, suggesting that inflammatory mediators may regulate these miRNAs. Transfecting epithelia with anti-miRs for miR-509-3p and miR-494, or inhibiting NF-κB signaling before stimulating cells with TNFα or IL-1β, suppressed these responses, suggesting that the expression of both miRNAs was responsive to NF-κB signaling. Thus, miR-509-3p and miR-494 are dynamic regulators of CFTR abundance and function in normal, non-CF airway epithelia.
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Marino G, Kotsias B. Cystic fibrosis transmembrane regulator (CFTR) in human trophoblast BeWo cells and its relation to cell migration. Placenta 2014; 35:92-8. [DOI: 10.1016/j.placenta.2013.12.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 12/03/2013] [Accepted: 12/12/2013] [Indexed: 11/25/2022]
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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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Ahner A, Gong X, Frizzell RA. Cystic fibrosis transmembrane conductance regulator degradation: cross-talk between the ubiquitylation and SUMOylation pathways. FEBS J 2013; 280:4430-8. [PMID: 23809253 DOI: 10.1111/febs.12415] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 06/24/2013] [Accepted: 06/25/2013] [Indexed: 12/26/2022]
Abstract
Defining the significant checkpoints in cystic fibrosis transmembrane conductance regulator (CFTR) biogenesis should identify targets for therapeutic intervention with CFTR folding mutants such as F508del. Although the role of ubiquitylation and the ubiquitin proteasome system is well established in the degradation of this common CFTR mutant, the part played by SUMOylation is a novel aspect of CFTR biogenesis/quality control. We identified this post-translational modification of CFTR as resulting from its interaction with small heat shock proteins (Hsps), which were found to selectively facilitate the degradation of F508del through a physical interaction with the SUMO (small ubiquitin-like modifier) E2 enzyme, Ubc9. Hsp27 promoted the SUMOylation of mutant CFTR by the SUMO-2 paralogue, which can form poly-chains. Poly-SUMO chains are then recognized by the SUMO-targeted ubiquitin ligase, RNF4, which elicited F508del degradation in a Hsp27-dependent manner. This work identifies a sequential connection between the SUMO and ubiquitin modifications of the CFTR mutant: Hsp27-mediated SUMO-2 modification, followed by ubiquitylation via RNF4 and degradation of the mutant via the proteasome. Other examples of the intricate cross-talk between the SUMO and ubiquitin pathways are discussed with reference to other substrates; many of these are competitive and lead to different outcomes. It is reasonable to anticipate that further research on SUMO-ubiquitin pathway interactions will identify additional layers of complexity in the process of CFTR biogenesis and quality control.
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Affiliation(s)
- Annette Ahner
- Department of Cell Biology, University of Pittsburgh School of Medicine, PA 15224, USA
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Ramachandran S, Krishnamurthy S, Jacobi AM, Wohlford-Lenane C, Behlke MA, Davidson BL, McCray PB. Efficient delivery of RNA interference oligonucleotides to polarized airway epithelia in vitro. Am J Physiol Lung Cell Mol Physiol 2013; 305:L23-32. [PMID: 23624792 DOI: 10.1152/ajplung.00426.2012] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Polarized and pseudostratified primary airway epithelia present barriers that significantly reduce their transfection efficiency and the efficacy of RNA interference oligonucleotides. This creates an impediment in studies of the airway epithelium, diminishing the utility of loss-of-function as a research tool. Here we outline methods to introduce RNAi oligonucleotides into primary human and porcine airway epithelia grown at an air-liquid interface and difficult-to-transfect transformed epithelial cell lines grown on plastic. At the time of plating, we reverse transfect small-interfering RNA (siRNA), Dicer-substrate siRNA, or microRNA oligonucleotides into cells by use of lipid or peptide transfection reagents. Using this approach we achieve significant knockdown in vitro of hypoxanthine-guanine phosphoribosyltransferase, IL-8, and CFTR expression at the mRNA and protein levels in 1-3 days. We also attain significant reduction of secreted IL-8 in polarized primary pig airway epithelia 3 days posttransfection and inhibition of CFTR-mediated Cl⁻ conductance in polarized air-liquid interface cultures of human airway epithelia 2 wk posttransfection. These results highlight an efficient means to deliver RNA interference reagents to airway epithelial cells and achieve significant knockdown of target gene expression and function. The ability to reliably conduct loss-of-function assays in polarized primary airway epithelia offers benefits to research in studies of epithelial cell homeostasis, candidate gene function, gene-based therapeutics, microRNA biology, and targeting the replication of respiratory viruses.
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Holleran JP, Zeng J, Frizzell RA, Watkins SC. Regulated recycling of mutant CFTR is partially restored by pharmacological treatment. J Cell Sci 2013; 126:2692-703. [PMID: 23572510 DOI: 10.1242/jcs.120196] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Efficient trafficking of the cystic fibrosis transmembrane conductance regulator (CFTR) to and from the cell surface is essential for maintaining channel density at the plasma membrane (PM) and ensuring proper physiological activity. The most common mutation, F508del, exhibits reduced surface expression and impaired function despite treatment with currently available pharmacological small molecules, called correctors. To gain more detailed insight into whether CFTR enters compartments that allow corrector stabilization in the cell periphery, we investigated the peripheral trafficking itineraries and kinetics of wild type (WT) and F508del in living cells using high-speed fluorescence microscopy together with fluorogen activating protein detection. We directly visualized internalization and accumulation of CFTR WT from the PM to a perinuclear compartment that colocalized with the endosomal recycling compartment (ERC) markers Rab11 and EHD1, reaching steady-state distribution by 25 minutes. Stimulation by protein kinase A (PKA) depleted this intracellular pool and redistributed CFTR channels to the cell surface, elicited by reduced endocytosis and active translocation to the PM. Corrector or temperature rescue of F508del also resulted in targeting to the ERC and exhibited subsequent PKA-stimulated trafficking to the PM. Corrector treatment (24 hours) led to persistent residence of F508del in the ERC, while thermally destabilized F508del was targeted to lysosomal compartments by 3 hours. Acute addition of individual correctors, C4 or C18, acted on peripheral trafficking steps to partially block lysosomal targeting of thermally destabilized F508del. Taken together, corrector treatment redirects F508del trafficking from a degradative pathway to a regulated recycling route, and proteins that mediate this process become potential targets for improving the efficacy of current and future correctors.
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Affiliation(s)
- John P Holleran
- University of Pittsburgh School of Medicine, Department of Cell Biology, BSTS 225, 3500 Terrace St, Pittsburgh, PA 15261, USA
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Chong PA, Kota P, Dokholyan NV, Forman-Kay JD. Dynamics intrinsic to cystic fibrosis transmembrane conductance regulator function and stability. Cold Spring Harb Perspect Med 2013; 3:a009522. [PMID: 23457292 DOI: 10.1101/cshperspect.a009522] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) requires dynamic fluctuations between states in its gating cycle for proper channel function, including changes in the interactions between the nucleotide-binding domains (NBDs) and between the intracellular domain (ICD) coupling helices and NBDs. Such motions are also linked with fluctuating phosphorylation-dependent binding of CFTR's disordered regulatory (R) region to the NBDs and partners. Folding of CFTR is highly inefficient, with the marginally stable NBD1 sampling excited states or folding intermediates that are aggregation-prone. The severe CF-causing F508del mutation exacerbates the folding inefficiency of CFTR and leads to impaired channel regulation and function, partly as a result of perturbed NBD1-ICD interactions and enhanced sampling of these NBD1 excited states. Increased knowledge of the dynamics within CFTR will expand our understanding of the regulated channel gating of the protein as well as of the F508del defects in folding and function.
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Affiliation(s)
- P Andrew Chong
- Program in Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
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Tucker TA, Fortenberry JA, Zsembery A, Schwiebert LM, Schwiebert EM. The ΔF508-CFTR mutation inhibits wild-type CFTR processing and function when co-expressed in human airway epithelia and in mouse nasal mucosa. BMC PHYSIOLOGY 2012; 12:12. [PMID: 22999299 PMCID: PMC3507716 DOI: 10.1186/1472-6793-12-12] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2012] [Accepted: 09/04/2012] [Indexed: 12/22/2022]
Abstract
BACKGROUND Rescue or correction of CFTR function in native epithelia is the ultimate goal of CF therapeutics development. Wild-type (WT) CFTR introduction and replacement is also of particular interest. Such therapies may be complicated by possible CFTR self-assembly into an oligomer or multimer. RESULTS Surprisingly, functional CFTR assays in native airway epithelia showed that the most common CFTR mutant, ΔF508-CFTR (ΔF-CFTR), inhibits WT-CFTR when both forms are co-expressed. To examine more mechanistically, both forms of CFTR were transfected transiently in varying amounts into IB3-1 CF human airway epithelial cells and HEK-293 human embryonic kidney cells null for endogenous CFTR protein expression. Increasing amounts of ΔF-CFTR inhibited WT-CFTR protein processing and function in CF human airway epithelial cells but not in heterologous HEK-293 cells. Stably expressed ΔF-CFTR in clones of the non-CF human airway epithelial cell line, CALU-3, also showed reduction in cAMP-stimulated anion secretion and in WT-CFTR processing. An ultimate test of this dominant negative-like effect of ΔF-CFTR on WT-CFTR was the parallel study of two different CF mouse models: the ΔF-CFTR mouse and the bitransgenic CFTR mouse corrected in the gut but null in the lung and airways. WT/ΔF heterozygotes had an intermediate phenotype with regard to CFTR agonist responses in in vivo nasal potential difference (NPD) recordings and in Ussing chamber recordings of short-circuit current (ISC) in vitro on primary tracheal epithelial cells isolated from the same mice. In contrast, CFTR bitransgenic +/- heterozygotes had no difference in their responses versus +/+ wild-type mice. CONCLUSIONS Taken altogether, these data suggest that ΔF-CFTR and WT-CFTR co-assemble into an oligomeric macromolecular complex in native epithelia and share protein processing machinery and regulation at the level of the endoplasmic reticulum (ER). As a consequence, ΔF-CFTR slows WT-CFTR protein processing and limits its expression and function in the apical membrane of native airway epithelia. Implications of these data for the relative health of CF heterozygous carriers, for CFTR protein processing in native airway epithelia, and for the relative efficacy of different CF therapeutic approaches is significant and is discussed.
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Affiliation(s)
- Torry A Tucker
- Departments of Cell Developmental and Integrative Biology, University of Alabama at Birmingham, 1918 University Blvd, Birmingham, AL 35294-0005, USA
- Gregory Fleming James Cystic Fibrosis (CF) Research Center, University of Alabama at Birmingham, 1918 University Blvd, Birmingham, 35294-0005 AL, USA
- Department of Biochemistry, University of Texas Health Sciences Center at Tyler, Tyler, TX, USA
| | - James A Fortenberry
- Gregory Fleming James Cystic Fibrosis (CF) Research Center, University of Alabama at Birmingham, 1918 University Blvd, Birmingham, 35294-0005 AL, USA
| | - Akos Zsembery
- Departments of Cell Developmental and Integrative Biology, University of Alabama at Birmingham, 1918 University Blvd, Birmingham, AL 35294-0005, USA
- Gregory Fleming James Cystic Fibrosis (CF) Research Center, University of Alabama at Birmingham, 1918 University Blvd, Birmingham, 35294-0005 AL, USA
- Department of Experimental Human Physiology, Semmelweis University, Budapest, Hungary
| | - Lisa M Schwiebert
- Departments of Cell Developmental and Integrative Biology, University of Alabama at Birmingham, 1918 University Blvd, Birmingham, AL 35294-0005, USA
- Gregory Fleming James Cystic Fibrosis (CF) Research Center, University of Alabama at Birmingham, 1918 University Blvd, Birmingham, 35294-0005 AL, USA
| | - Erik M Schwiebert
- Departments of Cell Developmental and Integrative Biology, University of Alabama at Birmingham, 1918 University Blvd, Birmingham, AL 35294-0005, USA
- Gregory Fleming James Cystic Fibrosis (CF) Research Center, University of Alabama at Birmingham, 1918 University Blvd, Birmingham, 35294-0005 AL, USA
- DiscoveryBioMed, Inc, Birmingham, AL, USA
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A microRNA network regulates expression and biosynthesis of wild-type and DeltaF508 mutant cystic fibrosis transmembrane conductance regulator. Proc Natl Acad Sci U S A 2012. [PMID: 22853952 DOI: 10.1073/+pnas.1210906109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Production of functional proteins requires multiple steps, including gene transcription and posttranslational processing. MicroRNAs (miRNAs) can regulate individual stages of these processes. Despite the importance of the cystic fibrosis transmembrane conductance regulator (CFTR) channel for epithelial anion transport, how its expression is regulated remains uncertain. We discovered that miRNA-138 regulates CFTR expression through its interactions with the transcriptional regulatory protein SIN3A. Treating airway epithelia with an miR-138 mimic increased CFTR mRNA and also enhanced CFTR abundance and transepithelial Cl(-) permeability independent of elevated mRNA levels. An miR-138 anti-miR had the opposite effects. Importantly, miR-138 altered the expression of many genes encoding proteins that associate with CFTR and may influence its biosynthesis. The most common CFTR mutation, ΔF508, causes protein misfolding, protein degradation, and cystic fibrosis. Remarkably, manipulating the miR-138 regulatory network also improved biosynthesis of CFTR-ΔF508 and restored Cl(-) transport to cystic fibrosis airway epithelia. This miRNA-regulated network directs gene expression from the chromosome to the cell membrane, indicating that an individual miRNA can control a cellular process more broadly than recognized previously. This discovery also provides therapeutic avenues for restoring CFTR function to cells affected by the most common cystic fibrosis mutation.
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A microRNA network regulates expression and biosynthesis of wild-type and DeltaF508 mutant cystic fibrosis transmembrane conductance regulator. Proc Natl Acad Sci U S A 2012; 109:13362-7. [PMID: 22853952 DOI: 10.1073/pnas.1210906109] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Production of functional proteins requires multiple steps, including gene transcription and posttranslational processing. MicroRNAs (miRNAs) can regulate individual stages of these processes. Despite the importance of the cystic fibrosis transmembrane conductance regulator (CFTR) channel for epithelial anion transport, how its expression is regulated remains uncertain. We discovered that miRNA-138 regulates CFTR expression through its interactions with the transcriptional regulatory protein SIN3A. Treating airway epithelia with an miR-138 mimic increased CFTR mRNA and also enhanced CFTR abundance and transepithelial Cl(-) permeability independent of elevated mRNA levels. An miR-138 anti-miR had the opposite effects. Importantly, miR-138 altered the expression of many genes encoding proteins that associate with CFTR and may influence its biosynthesis. The most common CFTR mutation, ΔF508, causes protein misfolding, protein degradation, and cystic fibrosis. Remarkably, manipulating the miR-138 regulatory network also improved biosynthesis of CFTR-ΔF508 and restored Cl(-) transport to cystic fibrosis airway epithelia. This miRNA-regulated network directs gene expression from the chromosome to the cell membrane, indicating that an individual miRNA can control a cellular process more broadly than recognized previously. This discovery also provides therapeutic avenues for restoring CFTR function to cells affected by the most common cystic fibrosis mutation.
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Guerriero CJ, Brodsky JL. The delicate balance between secreted protein folding and endoplasmic reticulum-associated degradation in human physiology. Physiol Rev 2012; 92:537-76. [PMID: 22535891 DOI: 10.1152/physrev.00027.2011] [Citation(s) in RCA: 301] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Protein folding is a complex, error-prone process that often results in an irreparable protein by-product. These by-products can be recognized by cellular quality control machineries and targeted for proteasome-dependent degradation. The folding of proteins in the secretory pathway adds another layer to the protein folding "problem," as the endoplasmic reticulum maintains a unique chemical environment within the cell. In fact, a growing number of diseases are attributed to defects in secretory protein folding, and many of these by-products are targeted for a process known as endoplasmic reticulum-associated degradation (ERAD). Since its discovery, research on the mechanisms underlying the ERAD pathway has provided new insights into how ERAD contributes to human health during both normal and diseases states. Links between ERAD and disease are evidenced from the loss of protein function as a result of degradation, chronic cellular stress when ERAD fails to keep up with misfolded protein production, and the ability of some pathogens to coopt the ERAD pathway. The growing number of ERAD substrates has also illuminated the differences in the machineries used to recognize and degrade a vast array of potential clients for this pathway. Despite all that is known about ERAD, many questions remain, and new paradigms will likely emerge. Clearly, the key to successful disease treatment lies within defining the molecular details of the ERAD pathway and in understanding how this conserved pathway selects and degrades an innumerable cast of substrates.
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Affiliation(s)
- Christopher J Guerriero
- Department of Biological Sciences, University of Pittsburgh, A320 Langley Hall, Pittsburgh, PA 15260, USA
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Identification of a novel duplication CFTRdup2 and functional impact of large rearrangements identified in the CFTR gene. Gene 2012; 500:194-8. [DOI: 10.1016/j.gene.2012.03.043] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 02/13/2012] [Accepted: 03/04/2012] [Indexed: 11/23/2022]
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He L, Skirkanich J, Moronetti L, Lewis R, Lamitina T. The cystic-fibrosis-associated ΔF508 mutation confers post-transcriptional destabilization on the C. elegans ABC transporter PGP-3. Dis Model Mech 2012; 5:930-9. [PMID: 22569626 PMCID: PMC3484874 DOI: 10.1242/dmm.008987] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Membrane proteins make up ∼30% of the proteome. During the early stages of maturation, this class of proteins can experience localized misfolding in distinct cellular compartments, such as the cytoplasm, endoplasmic reticulum (ER) lumen and ER membrane. ER quality control (ERQC) mechanisms monitor folding and determine whether a membrane protein is appropriately folded or is misfolded and warrants degradation. ERQC plays crucial roles in human diseases, such as cystic fibrosis, in which deletion of a single amino acid (F508) results in the misfolding and degradation of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl– channel. We introduced the ΔF508 mutation into Caenorhabditis elegans PGP-3, a 12-transmembrane ABC transporter with 15% identity to CFTR. When expressed in intestinal epithelial cells, PGP-3wt was stable and efficiently trafficked to the apical plasma membrane through a COPII-dependent mechanism. However, PGP-3ΔF508 was post-transcriptionally destabilized, resulting in reduced total and apical membrane protein levels. Genetic or physiological activation of the osmotic stress response pathway, which causes accumulation of the chemical chaperone glycerol, stabilized PGP-3ΔF508. Efficient degradation of PGP-3ΔF508 required the function of several C. elegans ER-associated degradation (ERAD) homologs, suggesting that destabilization occurs through an ERAD-type mechanism. Our studies show that the ΔF508 mutation causes post-transcriptional destabilization and degradation of PGP-3 in C. elegans epithelial cells. This model, combined with the power of C. elegans genetics, provides a new opportunity to genetically dissect metazoan ERQC.
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Affiliation(s)
- Liping He
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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Lukacs GL, Verkman AS. CFTR: folding, misfolding and correcting the ΔF508 conformational defect. Trends Mol Med 2011; 18:81-91. [PMID: 22138491 DOI: 10.1016/j.molmed.2011.10.003] [Citation(s) in RCA: 283] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 10/19/2011] [Accepted: 10/19/2011] [Indexed: 12/30/2022]
Abstract
Cystic fibrosis (CF), the most common lethal genetic disease in the Caucasian population, is caused by loss-of-function mutations of the CF transmembrane conductance regulator (CFTR), a cyclic AMP-regulated plasma membrane chloride channel. The most common mutation, deletion of phenylalanine 508 (ΔF508), impairs CFTR folding and, consequently, its biosynthetic and endocytic processing as well as chloride channel function. Pharmacological treatments may target the ΔF508 CFTR structural defect directly by binding to the mutant protein and/or indirectly by altering cellular protein homeostasis (proteostasis) to promote ΔF508 CFTR plasma membrane targeting and stability. This review discusses recent basic research aimed at elucidating the structural and trafficking defects of ΔF508 CFTR, a prerequisite for the rational design of CF therapy to correct the loss-of-function phenotype.
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Affiliation(s)
- Gergely L Lukacs
- Department of Physiology and GRASP, McGill University, Montréal, Quebec H3E 1Y6, Canada.
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Rowe SM, Sloane P, Tang LP, Backer K, Mazur M, Buckley-Lanier J, Nudelman I, Belakhov V, Bebok Z, Schwiebert E, Baasov T, Bedwell DM. Suppression of CFTR premature termination codons and rescue of CFTR protein and function by the synthetic aminoglycoside NB54. J Mol Med (Berl) 2011; 89:1149-61. [PMID: 21779978 DOI: 10.1007/s00109-011-0787-6] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 05/18/2011] [Accepted: 06/23/2011] [Indexed: 01/28/2023]
Abstract
Certain aminoglycosides are capable of inducing "translational readthrough" of premature termination codons (PTCs). However, toxicity and relative lack of efficacy deter treatment with clinically available aminoglycosides for genetic diseases caused by PTCs, including cystic fibrosis (CF). Using a structure-based approach, the novel aminoglycoside NB54 was developed that exhibits reduced toxicity and enhanced suppression of PTCs in cell-based reporter assays relative to gentamicin. We examined whether NB54 administration rescued CFTR protein and function in clinically relevant CF models. In a fluorescence-based halide efflux assay, NB54 partially restored halide efflux in a CF bronchial epithelial cell line (CFTR genotype W1282X/F508del), but not in a CF epithelial cell line lacking a PTC (F508del/F508del). In polarized airway epithelial cells expressing either a CFTR-W1282X or -G542X cDNA, treatment with NB54 increased stimulated short-circuit current (I (SC)) with greater efficiency than gentamicin. NB54 and gentamicin induced comparable increases in forskolin-stimulated I (SC) in primary airway epithelial cells derived from a G542X/F508del CF donor. Systemic administration of NB54 to Cftr-/- mice expressing a human CFTR-G542X transgene restored 15-17% of the average stimulated transepithelial chloride currents observed in wild-type (Cftr+/+) mice, comparable to gentamicin. NB54 exhibited reduced cellular toxicity in vitro and was tolerated at higher concentrations than gentamicin in vivo. These results provide evidence that synthetic aminoglycosides are capable of PTC suppression in relevant human CF cells and a CF animal model and support further development of these compounds as a treatment modality for genetic diseases caused by PTCs.
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Affiliation(s)
- Steven M Rowe
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA.
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Ostedgaard LS, Meyerholz DK, Chen JH, Pezzulo AA, Karp PH, Rokhlina T, Ernst SE, Hanfland RA, Reznikov LR, Ludwig PS, Rogan MP, Davis GJ, Dohrn CL, Wohlford-Lenane C, Taft PJ, Rector MV, Hornick E, Nassar BS, Samuel M, Zhang Y, Richter SS, Uc A, Shilyansky J, Prather RS, McCray PB, Zabner J, Welsh MJ, Stoltz DA. The ΔF508 mutation causes CFTR misprocessing and cystic fibrosis-like disease in pigs. Sci Transl Med 2011; 3:74ra24. [PMID: 21411740 DOI: 10.1126/scitranslmed.3001868] [Citation(s) in RCA: 160] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Cystic fibrosis (CF) is an autosomal recessive disease caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) anion channel. The most common CF-associated mutation is ΔF508, which deletes a phenylalanine in position 508. In vitro studies indicate that the resultant protein, CFTR-ΔF508, is misprocessed, although the in vivo consequences of this mutation remain uncertain. To better understand the effects of the ΔF508 mutation in vivo, we produced CFTR(ΔF508/ΔF508) pigs. Our biochemical, immunocytochemical, and electrophysiological data on CFTR-ΔF508 in newborn pigs paralleled in vitro predictions. They also indicated that CFTR(ΔF508/ΔF508) airway epithelia retain a small residual CFTR conductance, with maximal stimulation producing ~6% of wild-type function. Cyclic adenosine 3',5'-monophosphate (cAMP) agonists were less potent at stimulating current in CFTR(Δ)(F508/)(Δ)(F508) epithelia, suggesting that quantitative tests of maximal anion current may overestimate transport under physiological conditions. Despite residual CFTR function, four older CFTR(ΔF508/ΔF508) pigs developed lung disease similar to human CF. These results suggest that this limited CFTR activity is insufficient to prevent lung or gastrointestinal disease in CF pigs. These data also suggest that studies of recombinant CFTR-ΔF508 misprocessing predict in vivo behavior, which validates its use in biochemical and drug discovery experiments. These findings help elucidate the molecular pathogenesis of the common CF mutation and will guide strategies for developing new therapeutics.
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Affiliation(s)
- Lynda S Ostedgaard
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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Qu F, Liu HJ, Xiang Y, Tan YR, Liu C, Zhu XL, Qin XQ. Activation of CFTR trafficking and gating by vasoactive intestinal peptide in human bronchial epithelial cells. J Cell Biochem 2011; 112:902-8. [PMID: 21328463 DOI: 10.1002/jcb.22999] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Cystic fibrosis transmembrane conductance regulator (CFTR) is an apical membrane chloride channel critical to the regulation of fluid, chloride, and bicarbonate transport in epithelia and other cell types. The most common cause of cystic fibrosis (CF) is the abnormal trafficking of CFTR mutants. Therefore, understanding the cellular machineries that transit CFTR from the endoplasmic reticulum to the cell surface is important. Vasoactive intestinal polypeptide (VIP) plays an important role in CFTR-dependent chloride transport. The present study was designed to observe the affection of VIP on the trafficking of CFTR, and channel gating in human bronchial epithelium cells (HBEC). Confocal microscopy revealed CFTR immunofluorescence extending from the apical membrane deeply into the cell cytoplasm. After VIP treatment, apical extension of CFTR immunofluorescence into the cell was reduced and the peak intensity of CFTR fluorescence shifted towards the apical membrane. Western blot showed VIP increased cell surface and total CFTR. Compared with the augmented level of total CFTR, the surface CFTR increased more markedly. Immunoprecipitation founded that the mature form of CFTR had a marked increase in HBEC treated with VIP. VIP led to a threefold increase in Cl(-) efflux in HBEC. Glibenclamide-sensitive and DIDS-insensitive CFTR Cl(-) currents were consistently observed after stimulation with VIP (10(-8) mol/L). The augmentation of CFTR Cl(-) currents enhanced by VIP (10(-8) mol/L) was reversed, at least in part, by the protein kinase A (PKA) inhibitor, H-89 and the protein kinase C (PKC) inhibitor, H-7, suggesting PKA and PKC participate in the VIP-promoted CFTR Cl(-) currents.
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Affiliation(s)
- Fei Qu
- Department of Physiology, Xiangya School of Medicine, Central South University, Changsha, Hunan 410078, China
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48
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Almomani EY, Chu CY, Cordat E. Mis-trafficking of bicarbonate transporters: implications to human diseasesThis paper is one of a selection of papers published in a Special Issue entitled CSBMCB 53rd Annual Meeting — Membrane Proteins in Health and Disease, and has undergone the Journal’s usual peer review process. Biochem Cell Biol 2011; 89:157-77. [DOI: 10.1139/o10-153] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Bicarbonate is a waste product of mitochondrial respiration and one of the main buffers in the human body. Thus, bicarbonate transporters play an essential role in maintaining acid-base balance but also during fetal development as they ensure tight regulation of cytosolic and extracellular environments. Bicarbonate transporters belong to two gene families, SLC4A and SLC26A. Proteins from these two families are widely expressed, and thus mutations in their genes result in various diseases that affect bones, pancreas, reproduction, brain, kidneys, eyes, heart, thyroid, red blood cells, and lungs. In this minireview, we discuss the current state of knowledge regarding the effect of SLC4A and SLC26A mutants, with a special emphasis on mutants that have been studied in mammalian cell lines and how they correlate with phenotypes observed in mice models.
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Affiliation(s)
- Ensaf Y. Almomani
- Membrane Protein Research Group, Department of Physiology, School of Molecular and Systems Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Carmen Y.S. Chu
- Membrane Protein Research Group, Department of Physiology, School of Molecular and Systems Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Emmanuelle Cordat
- Membrane Protein Research Group, Department of Physiology, School of Molecular and Systems Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
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Bartoszewski R, Rab A, Fu L, Bartoszewska S, Collawn J, Bebok Z. CFTR expression regulation by the unfolded protein response. Methods Enzymol 2011; 491:3-24. [PMID: 21329791 DOI: 10.1016/b978-0-12-385928-0.00001-8] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) is a chloride channel and key regulator of epithelial functions. Mutations in the CFTR gene lead to reduced or dysfunctional CFTR protein and cause cystic fibrosis (CF), a generalized exocrinopathy affecting multiple organs. In the airways, loss of CFTR function leads to thickened mucus, reduced mucociliary clearance, chronic infections, and respiratory failure. Common airway disorders such as bronchitis and chronic obstructive pulmonary disease (COPD) also present CF-like symptoms such as mucus congestion and chronic inflammation without mutations in CFTR. The primary risk factors for COPD and chronic bronchitis include environmental stress insults such as pollutants and infections that often result in hypoxic conditions. Furthermore, environmental factors such as cigarette smoke and reactive oxygen species have been implicated in reduced CFTR function. Activation of cellular stress responses by these factors promotes differential, stress-associated gene expression regulation. During our investigations on the mechanisms of CFTR expression regulation, we have shown that the ER stress response, the unfolded protein response (UPR), decreases CFTR expression at the transcriptional, translational, and maturational levels. Here, we provide a detailed description of the methods we employ to study CFTR expression regulation by the UPR. Similar approaches are applicable in studies on other genes and how they are affected by the UPR.
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Affiliation(s)
- Rafal Bartoszewski
- Department of Cell Biology, University of Alabama at Birmingham, Birmingham, Alabama, USA
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50
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Pyle LC, Fulton JC, Sloane PA, Backer K, Mazur M, Prasain J, Barnes S, Clancy JP, Rowe SM. Activation of the cystic fibrosis transmembrane conductance regulator by the flavonoid quercetin: potential use as a biomarker of ΔF508 cystic fibrosis transmembrane conductance regulator rescue. Am J Respir Cell Mol Biol 2010; 43:607-616. [PMID: 20042712 PMCID: PMC2970857 DOI: 10.1165/rcmb.2009-0281oc] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Accepted: 10/24/2009] [Indexed: 12/10/2023] Open
Abstract
Therapies to correct the ΔF508 cystic fibrosis transmembrane conductance regulator (CFTR) folding defect require sensitive methods to detect channel activity in vivo. The β₂ adrenergic receptor agonists, which provide the CFTR stimuli commonly used in nasal potential difference assays, may not overcome the channel gating defects seen in ΔF508 CFTR after plasma membrane localization. In this study, we identify an agent, quercetin, that enhances the detection of surface ΔF508 CFTR, and is suitable for nasal perfusion. A screen of flavonoids in CFBE41o⁻ cells stably transduced with ΔF508 CFTR, corrected to the cell surface with low temperature growth, revealed that quercetin stimulated an increase in the short-circuit current. This increase was dose-dependent in both Fisher rat thyroid and CFBE41o⁻ cells. High concentrations inhibited Cl⁻ conductance. In CFBE41o⁻ airway cells, quercetin (20 μg/ml) activated ΔF508 CFTR, whereas the β₂ adrenergic receptor agonist isoproterenol did not. Quercetin had limited effects on cAMP levels, but did not produce detectable phosphorylation of the isolated CFTR R-domain, suggesting an activation independent of channel phosphorylation. When perfused in the nares of Cftr(+) mice, quercetin (20 μg/ml) produced a hyperpolarization of the potential difference that was absent in Cftr(-/-) mice. Finally, quercetin-induced, dose-dependent hyperpolarization of the nasal potential difference was also seen in normal human subjects. Quercetin activates CFTR-mediated anion transport in respiratory epithelia in vitro and in vivo, and may be useful in studies intended to detect the rescue of ΔF508 CFTR by nasal potential difference.
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Affiliation(s)
- Louise C. Pyle
- Departments of Medicine, Pediatrics, Pharmacology, Genetics, and Physiology, and Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama
| | - Jennifer C. Fulton
- Departments of Medicine, Pediatrics, Pharmacology, Genetics, and Physiology, and Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama
| | - Peter A. Sloane
- Departments of Medicine, Pediatrics, Pharmacology, Genetics, and Physiology, and Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama
| | - Kyle Backer
- Departments of Medicine, Pediatrics, Pharmacology, Genetics, and Physiology, and Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama
| | - Marina Mazur
- Departments of Medicine, Pediatrics, Pharmacology, Genetics, and Physiology, and Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama
| | - Jeevan Prasain
- Departments of Medicine, Pediatrics, Pharmacology, Genetics, and Physiology, and Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama
| | - Stephen Barnes
- Departments of Medicine, Pediatrics, Pharmacology, Genetics, and Physiology, and Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama
| | - J. P. Clancy
- Departments of Medicine, Pediatrics, Pharmacology, Genetics, and Physiology, and Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama
| | - Steven M. Rowe
- Departments of Medicine, Pediatrics, Pharmacology, Genetics, and Physiology, and Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama
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