scholarly journals VX-809 corrects folding defects in cystic fibrosis transmembrane conductance regulator protein through action on membrane-spanning domain 1

2013 ◽  
Vol 24 (19) ◽  
pp. 3016-3024 ◽  
Author(s):  
Hong Yu Ren ◽  
Diane E. Grove ◽  
Oxana De La Rosa ◽  
Scott A. Houck ◽  
Pattarawut Sopha ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Chloride Transport ◽  
Genetic Disorder ◽  
Missense Mutations ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Regulator Protein ◽  
Folding Defect ◽  
Membrane Spanning ◽  
Cf Transmembrane Conductance Regulator

Cystic fibrosis (CF) is a fatal genetic disorder associated with defective hydration of lung airways due to the loss of chloride transport through the CF transmembrane conductance regulator protein (CFTR). CFTR contains two membrane-spanning domains (MSDs), two nucleotide-binding domains (NBDs), and a regulatory domain, and its channel assembly requires multiple interdomain contacts. The most common CF-causing mutation, F508del, occurs in NBD1 and results in misfolding and premature degradation of F508del-CFTR. VX-809 is an investigational CFTR corrector that partially restores CFTR function in people who are homozygous for F508del-CFTR. To identify the folding defect(s) in F508del-CFTR that must be repaired to treat CF, we explored the mechanism of VX-809 action. VX-809 stabilized an N-terminal domain in CFTR that contains only MSD1 and efficaciously restored function to CFTR forms that have missense mutations in MSD1. The action of VX-809 on MSD1 appears to suppress folding defects in F508del-CFTR by enhancing interactions among the NBD1, MSD1, and MSD2 domains. The ability of VX-809 to correct F508del-CFTR is enhanced when combined with mutations that improve F508del-NBD1 interaction with MSD2. These data suggest that the use of VX-809 in combination with an additional CFTR corrector that suppresses folding defects downstream of MSD1 may further enhance CFTR function in people with F508del-CFTR.

scholarly journals Maturation and function of cystic fibrosis transmembrane conductance regulator variants bearing mutations in putative nucleotide-binding domains 1 and 2.

1991 ◽  
Vol 11 (8) ◽  
pp. 3886-3893 ◽  
Author(s):  
R J Gregory ◽  
D P Rich ◽  
S H Cheng ◽  
D W Souza ◽  
S Paul ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Amino Acid ◽  
Functional Activity ◽  
Nucleotide Binding ◽  
Missense Mutations ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Fluorescence Measurements ◽  
Cf Transmembrane Conductance Regulator ◽  
Altered Proteins

One feature of the mutations thus far found to be associated with the disease cystic fibrosis (CF) is that many of them are clustered within the first nucleotide-binding domain (NBD) of the CF transmembrane conductance regulator (CFTR). We sought to discover the molecular basis for this clustering by introducing into the two NBDs of CFTR mutations either mimicking amino acid changes associated with CF or altering residues within highly conserved motifs. Synthesis and maturation of the mutant CFTR were studied by transient expression in COS cells. The ability of the altered proteins to generate cyclic AMP-stimulated anion efflux was assessed by using 6-methoxy-N-(sulfopropyl) quinolinium (SPQ) fluorescence measurements in HeLa cells expressing mutated plasmids. The results show that (i) all CF-associated mutants, with one exception, lack functional activity as measured in the SPQ assay, (ii) mutations in NBD1 are more sensitive to the effects of the same amino acid change than are the corresponding mutations in NBD2, (iii) cells transfected with plasmids bearing CF-associated mutations commonly but not exclusively lack mature CFTR, (iv) NBD mutants lacking mature CFTR fail to activate Cl- channels, and (v) the glycosylation of CFTR, per se, is not required for CFTR function. We reason that the structure of NBD1 itself or of the surrounding domains renders it particularly sensitive to mutational changes. As a result, most NBD1 mutants, but only a few NBD2 mutants, fail to mature or lack functional activity. These findings are consistent with the observed uneven distribution of CFTR missense mutations between NBD1 and NBD2 of CF patients.

scholarly journals CFTR misfolds during native-centric simulations due to entropic penalties of native state formation

2018 ◽  
Author(s):  
J. Shi ◽  
T. Cleveland ◽  
A. C. Powe ◽  
G. McGaughey ◽  
V. S. Pande
Keyword(s):  
Cystic Fibrosis ◽  
Genetic Disorder ◽  
Dynamics Simulation ◽  
Transmembrane Conductance Regulator ◽  
Free Energy Surface ◽  
Transmembrane Conductance ◽  
Regulator Protein ◽  
Kinetic Traps ◽  
Induced Defects

AbstractCystic fibrosis (CF) is a common genetic disorder that affects approximately 70,000 people worldwide. It is caused by mutation-induced defects in synthesis, folding, processing, or function of the Cystic Fibrosis Transmembrane conductance Regulator protein (CFTR), a chloride-selective ion channel required for the proper functioning of secretory epithelia in tissues such as the lung, pancreas, and skin. The most common cause of CF is the single-residue deletion of F508 (F508del), a mutation present in one or both alleles in 90% of patients that induces severe folding defects and results in greatly reduced expression of the protein. Despite its medical importance, high-resolution mechanistic information about CFTR folding is lacking. In this study, we used molecular dynamics simulation with a native-centric force field to examine the folding and assembly of both full-length CFTR and the isolated first nucleotide-binding domain (NBD1). We observed that the protein was capable of substantial misfolding on both the intradomain and interdomain scale due to entropically favorable kinetic traps that exist on CFTR’s folding free energy surface. These results suggest that even wild type CFTR, in the absence of any disease-related mutations, has suboptimal folding efficiency. We speculate that such entropically-driven misfolding also occurs in disease-prone mutants such as F508del and contributes to the protein’s poor in vivo activity.

scholarly journals Modulation of Ion Transport to Restore Airway Hydration in Cystic Fibrosis

Genes ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 453
Author(s):  
James A. Reihill ◽  
Lisa E. J. Douglas ◽  
S. Lorraine Martin
Keyword(s):  
Cystic Fibrosis ◽  
Epithelial Cells ◽  
Genetic Disorder ◽  
Airway Epithelial Cells ◽  
Transmembrane Conductance Regulator ◽  
Airway Epithelial ◽  
Loss Of Function ◽  
Transmembrane Conductance ◽  
Infection And Inflammation ◽  
Cf Transmembrane Conductance Regulator

Cystic fibrosis (CF) is a life-limiting genetic disorder caused by loss-of-function mutations in the gene which codes for the CF transmembrane conductance regulator (CFTR) Cl− channel. Loss of Cl− secretion across the apical membrane of airway lining epithelial cells results in dehydration of the airway surface liquid (ASL) layer which impairs mucociliary clearance (MCC), and as a consequence promotes bacterial infection and inflammation of the airways. Interventions that restore airway hydration are known to improve MCC. Here we review the ion channels present at the luminal surface of airway epithelial cells that may be targeted to improve airway hydration and MCC in CF airways.

scholarly journals Vardenafil increases intracellular accumulation of the most prevalent mutant cystic fibrosis transmembrane conductance regulator (CTFR) in human bronchial epithelial cells

Biology Open ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. bio053116
Author(s):  
Barbara Dhooghe ◽  
Caroline Bouzin ◽  
Angélique Mottais ◽  
Emmanuel Hermans ◽  
Martial Delion ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Cell Lines ◽  
Chloride Transport ◽  
Pde5 Inhibitor ◽  
Inhibitory Effect ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Transient Rise ◽  
Phosphodiesterase Type ◽  
Cf Transmembrane Conductance Regulator

ABSTRACTCystic fibrosis (CF) is a genetic disease characterized by progressive lung and chronic digestive manifestations. We have shown that therapeutic doses of vardenafil, a phosphodiesterase type 5 (PDE5) inhibitor, corrects CF Transmembrane conductance Regulator (CFTR)-dependent chloride transport in respiratory and intestinal tissues of F508del homozygous mice. Here, we studied the effect of vardenafil on CFTR in 16HBE14o– and CFBE41o− cell lines. First, the expression levels of PDE5 mRNA in these cell lines were monitored. The two cell lines were exposed to different drugs (dimethyl sulfoxide, 8-Br-cGMP, forskolin or vardenafil). The cAMP and cGMP intracellular concentrations were measured. Finally, we localised the CFTR by immunolabelling. PDE5 was similarly expressed in both wild-type and in CF cells. A fast and transient rise in cGMP intracellular contents followed treatment with vardenafil, confirming its PDE5 inhibitory effect. We showed that vardenafil promoted both the early steps of the cellular processing and the trafficking of F508del without fully addressing the protein to the plasma membrane. The effect was not reproduced by the brominated cGMP analogue and it was not prevented by the combination of a protein kinase G (PKG) inhibitor and vardenafil. These findings support the view that vardenafil partially rescues F508del through cGMP/PKG-independent mechanisms.

scholarly journals Aspirin and Some Other Nonsteroidal Anti-Inflammatory Drugs Inhibit Cystic Fibrosis Transmembrane Conductance Regulator Protein Gene Expression in T-84 Cells

1999 ◽  
Vol 8 (4-5) ◽  
pp. 219-227 ◽  
Author(s):  
Danielle Tondelier ◽  
Franck Brouillard ◽  
Joanna Lipecka ◽  
Régis Labarthe ◽  
Moëz Bali ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cystic Fibrosis ◽  
Chloride Transport ◽  
Clinical Manifestations ◽  
Cftr Gene ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Regulator Protein ◽  
Inflammatory Drugs ◽  
Anti Inflammatory

Cystic fibrosis (CF) is caused by mutations in the CF gene, which encodes CF transmembrane conductance regulator protein (CFTR), a transmembrane protein that acts as a cAMP-regulated chloride channel. The disease is characterized by inflammation but the relationship between inflammation, abnormal transepithelial ion transport, and the clinical manifestations of CF are uncertain. The present study was undertaken to determine whether three nonsteroidal anti-inflammatory drugs (NSAIDs) (aspirin, ibuprofen, and indomethacin) modulate CFTR gene expression in T-84 cells. Treatment with NSAIDs reduced CFTR transcripts, and decreased cAMP-stimulated anion fluxes, an index of CFTR function. However, the two phenomena occurred at different concentrations of both drugs. The results indicate that NSAIDs can regulate both CFTR gene expression and the function of CFTR-related chloride transport, and suggest that NSAIDs act via multiple transduction pathways.

scholarly journals Alteration of CFTR transmembrane span integration by disease-causing mutations

2011 ◽  
Vol 22 (23) ◽  
pp. 4461-4471 ◽  
Author(s):  
Anna E. Patrick ◽  
Andrey L. Karamyshev ◽  
Linda Millen ◽  
Philip J. Thomas
Keyword(s):  
Cystic Fibrosis ◽  
Endoplasmic Reticulum ◽  
Side Chain ◽  
Missense Mutations ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Temperature Dependent ◽  
Regulator Protein ◽  
Cystic Fibrosis Transmembrane ◽  
Transmembrane Span

Many missense mutations in the cystic fibrosis transmembrane conductance regulator protein (CFTR) result in its misfolding, endoplasmic reticulum (ER) accumulation, and, thus, cystic fibrosis. A number of these mutations are located in the predicted CFTR transmembrane (TM) spans and have been projected to alter span integration. However, the boundaries of the spans have not been precisely defined experimentally. In this study, the ER luminal integration profiles of TM1 and TM2 were determined using the ER glycosylation machinery, and the effects of the CF-causing mutations G85E and G91R thereon were assessed. The mutations either destabilize the integrated conformation or alter the TM1 ER integration profile. G85E misfolding is based in TM1 destabilization by glutamic acid and loss of glycine and correlates with the temperature-insensitive ER accumulation of immature full-length CFTR harboring the mutation. By contrast, temperature-dependent misfolding owing to the G91R mutation depends on the introduction of the basic side chain rather than the loss of the glycine. This work demonstrates that CF-causing mutations predicted to have similar effects on CFTR structure actually result in disparate molecular perturbations that underlie ER accumulation and the pathology of CF.

Maturation and function of cystic fibrosis transmembrane conductance regulator variants bearing mutations in putative nucleotide-binding domains 1 and 2

1991 ◽  
Vol 11 (8) ◽  
pp. 3886-3893
Author(s):  
R J Gregory ◽  
D P Rich ◽  
S H Cheng ◽  
D W Souza ◽  
S Paul ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Amino Acid ◽  
Functional Activity ◽  
Nucleotide Binding ◽  
Missense Mutations ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Fluorescence Measurements ◽  
Cf Transmembrane Conductance Regulator ◽  
Altered Proteins

One feature of the mutations thus far found to be associated with the disease cystic fibrosis (CF) is that many of them are clustered within the first nucleotide-binding domain (NBD) of the CF transmembrane conductance regulator (CFTR). We sought to discover the molecular basis for this clustering by introducing into the two NBDs of CFTR mutations either mimicking amino acid changes associated with CF or altering residues within highly conserved motifs. Synthesis and maturation of the mutant CFTR were studied by transient expression in COS cells. The ability of the altered proteins to generate cyclic AMP-stimulated anion efflux was assessed by using 6-methoxy-N-(sulfopropyl) quinolinium (SPQ) fluorescence measurements in HeLa cells expressing mutated plasmids. The results show that (i) all CF-associated mutants, with one exception, lack functional activity as measured in the SPQ assay, (ii) mutations in NBD1 are more sensitive to the effects of the same amino acid change than are the corresponding mutations in NBD2, (iii) cells transfected with plasmids bearing CF-associated mutations commonly but not exclusively lack mature CFTR, (iv) NBD mutants lacking mature CFTR fail to activate Cl- channels, and (v) the glycosylation of CFTR, per se, is not required for CFTR function. We reason that the structure of NBD1 itself or of the surrounding domains renders it particularly sensitive to mutational changes. As a result, most NBD1 mutants, but only a few NBD2 mutants, fail to mature or lack functional activity. These findings are consistent with the observed uneven distribution of CFTR missense mutations between NBD1 and NBD2 of CF patients.

Liquid secretion inhibitors reduce mucociliary transport in glandular airways

2002 ◽  
Vol 283 (2) ◽  
pp. L329-L335 ◽  
Author(s):  
Stephen T. Ballard ◽  
Laura Trout ◽  
Anil Mehta ◽  
Sarah K. Inglis
Keyword(s):  
Beat Frequency ◽  
Anion Channel ◽  
Ciliary Beat Frequency ◽  
Mucociliary Transport ◽  
Transmembrane Conductance Regulator ◽  
Inhibitory Effects ◽  
Transmembrane Conductance ◽  
Regulator Protein ◽  
Liquid Absorption ◽  
Cf Transmembrane Conductance Regulator

Because of its possible importance in cystic fibrosis (CF) pulmonary pathogenesis, the effect of anion and liquid secretion inhibitors on airway mucociliary transport was examined. When excised porcine tracheas were treated with ACh to induce gland liquid secretion, the rate of mucociliary transport was increased nearly threefold from 2.5 ± 0.5 to 6.8 ± 0.8 mm/min. Pretreatment with both bumetanide and dimethylamiloride (DMA), to respectively inhibit Cl− and HCO[Formula: see text]secretion, significantly reduced mucociliary transport in the presence of ACh by 92%. Pretreatment with the anion channel blocker 5-nitro-2-(3-phenylpropylamino)benzoic acid similarly reduced mucociliary transport in ACh-treated airways by 97%. These agents did not, however, reduce ciliary beat frequency. Luminal application of benzamil to block liquid absorption significantly attenuated the inhibitory effects of bumetanide and DMA on mucociliary transport. We conclude that anion and liquid secretion is essential for normal mucociliary transport in glandular airways. Because the CF transmembrane conductance regulator protein likely mediates Cl−, HCO[Formula: see text], and liquid secretion in normal glands, we speculate that impairment of gland liquid secretion significantly contributes to defective mucociliary transport in CF.

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