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Damien Adam, Claudia Bilodeau, Laura Sognigbé, Émilie Maillé, Manon Ruffin, Emmanuelle Brochiero
BACKGROUND: Progressive airway damage due to bacterial infections, especially with Pseudomonas aeruginosa remains the first cause of morbidity and mortality in CF patients. Our previous work revealed a repair delay in CF airway epithelia compared to non-CF. This delay was partially prevented after CFTR correction (with VRT-325) in the absence of infection. Our goals were now to evaluate the effect of the Orkambi combination (CFTR VX-809 corrector + VX-770 potentiator) on the repair of CF primary airway epithelia, in infectious conditions...
April 13, 2018: Journal of Cystic Fibrosis: Official Journal of the European Cystic Fibrosis Society
Onofrio Laselva, Steven Molinski, Valeria Casavola, Christine E Bear
The most common Cystic Fibrosis causing mutation is deletion of phenylalanine 508 (F508del), a mutation that leads to protein misassembly with defective processing. Small molecule correctors compounds: VX-809 or Corr-4a (C4) partially restore processing of the major mutant. These two prototypical corrector compounds cause an additive effect on F508del-CFTR processing and hence were proposed to act through distinct mechanisms: VX-809 stabilizing the first membrane spanning domain 1 (MSD1) and C4, acting on the second half of the molecule (consisting of MSD2 and/or nucleotide binding domain 2 (NBD2))...
April 4, 2018: Molecular Pharmacology
Steven V Molinski, Vijay M Shahani, Adithya S Subramanian, Stephen S MacKinnon, Geoffrey Woollard, Marcon Laforet, Onofrio Laselva, Leonard D Morayniss, Christine E Bear, Andreas Windemuth
Cystic Fibrosis (CF) is caused by mutations in the CFTR gene, of which over 2000 have been reported to date. Mutations have yet to be analyzed in aggregate to assess their distribution across the tertiary structure of the CFTR protein, an approach that could provide valuable insights into the structure-function relationship of CFTR. In addition, the binding site of Class I correctors (VX-809, VX-661, and C18) is not well understood. In this study, exonic CFTR mutations and mutant allele frequencies described in 3 curated databases (ABCMdb, CFTR1, and CFTR2, comprising >130 000 data points) were mapped to 2 different structural models: a homology model of full-length CFTR protein in the open-channel state, and a cryo-electron microscopy core-structure of CFTR in the closed-channel state...
March 23, 2018: Proteins
Lydia A Perkins, Gregory W Fisher, Matharishwan Naganbabu, Brigitte F Schmidt, Frederick Mun, Marcel P Bruchez
The most promising F508del-CFTR corrector, VX-809, has been unsuccessful as an effective, stand-alone treatment for CF patients, but the rescue effect in combination with other drugs may confer an acceptable level of therapeutic benefit. Targeting cellular factors that modify trafficking may act to enhance the cell surface density of F508-CFTR with VX-809 correction. Our goal is to identify druggable kinases that enhance F508del-CFTR rescue and stabilization at the cell surface beyond that achievable with the VX-809 corrector alone...
March 5, 2018: Molecular Pharmaceutics
Manon Ruffin, Lucie Roussel, Émilie Maillé, Simon Rousseau, Emmanuelle Brochiero
Cystic fibrosis patients exhibit chronic Pseudomonas aeruginosa respiratory infections and sustained proinflammatory state favoring lung tissue damage and remodeling, ultimately leading to respiratory failure. Loss of cystic fibrosis transmembrane conductance regulator (CFTR) function is associated with MAPK hyperactivation and increased cytokines expression, such as interleukin-8 [chemoattractant chemokine (C-X-C motif) ligand 8 (CXCL8)]. Recently, new therapeutic strategies directly targeting the basic CFTR defect have been developed, and ORKAMBI (Vx-809/Vx-770 combination) is the only Food and Drug Administration-approved treatment for CF patients homozygous for the F508del mutation...
April 1, 2018: American Journal of Physiology. Lung Cellular and Molecular Physiology
Raëd Farhat, Ayman El-Seedy, Caroline Norez, Hugo Talbot, Marie-Claude Pasquet, Catherine Adolphe, Alain Kitzis, Véronique Ladevèze
Cystic Fibrosis is the most common recessive autosomal rare disease found in Caucasian. It is caused by mutations on the Cystic Fibrosis Transmembrane Conductance Regulator gene (CFTR) that encodes for a protein located on the apical membrane of epithelial cells. c.3909C>G (p.Asn1303Lys) is one of the most common worldwide mutations located in nucleotide binding domain 2. The effect of the p.Asn1303Lys mutation on misprocessing was studied by immunofluorescence and western blotting analysis in presence and absence of treatment...
November 30, 2017: Cellular and Molecular Biology
Émilie Maillé, Manon Ruffin, Damien Adam, Hatem Messaoud, Shantelle L Lafayette, Geoffrey McKay, Dao Nguyen, Emmanuelle Brochiero
The function of cystic fibrosis transmembrane conductance regulator (CFTR) channels is crucial in human airways. However unfortunately, chronic Pseudomonas aeruginosa infection has been shown to impair CFTR proteins in non-CF airway epithelial cells (AEC) and to alter the efficiency of new treatments with CFTR modulators designed to correct the basic CFTR default in AEC from cystic fibrosis (CF) patients carrying the F508del mutation. Our aim was first to compare the effect of laboratory strains, clinical isolates, engineered and natural mutants to determine the role of the LasR quorum sensing system in CFTR impairment, and second, to test the efficiency of a quorum sensing inhibitor to counteract the deleterious impact of P...
2017: Frontiers in Cellular and Infection Microbiology
Roxanna Barnaby, Katja Koeppen, Amanda Nymon, Thomas H Hampton, Brent Berwin, Alix Ashare, Bruce A Stanton
Cystic fibrosis (CF), the most common lethal genetic disease in Caucasians, is characterized by chronic bacterial lung infection and excessive inflammation, which lead to progressive loss of lung function and premature death. Although ivacaftor (VX-770) alone and ivacaftor in combination with lumacaftor (VX-809) improve lung function in CF patients with the Gly551Asp and del508Phe mutations, respectively, the effects of these drugs on the function of human CF macrophages are unknown. Thus studies were conducted to examine the effects of lumacaftor alone and lumacaftor in combination with ivacaftor (i...
March 1, 2018: American Journal of Physiology. Lung Cellular and Molecular Physiology
Kavisha Arora, Yunjie Huang, Kyushik Mun, Sunitha Yarlagadda, Nambirajan Sundaram, Marco M Kessler, Gerhard Hannig, Caroline B Kurtz, Inmaculada Silos-Santiago, Michael Helmrath, Joseph J Palermo, John P Clancy, Kris A Steinbrecher, Anjaparavanda P Naren
Cystic fibrosis (CF) is a genetic disorder in which epithelium-generated fluid flow from the lung, intestine, and pancreas is impaired due to mutations disrupting CF transmembrane conductance regulator (CFTR) channel function. CF manifestations of the pancreas and lung are present in the vast majority of CF patients, and 15% of CF infants are born with obstructed gut or meconium ileus. However, constipation is a significantly underreported outcome of CF disease, affecting 47% of the CF patients, and management becomes critical in the wake of increasing life span of CF patients...
October 5, 2017: JCI Insight
Francis H Wong, Asmahan AbuArish, Elizabeth Matthes, Mark J Turner, Lana E Greene, Alexandre Cloutier, Renaud Robert, David Y Thomas, Gonzalo Cosa, André M Cantin, John W Hanrahan
Air pollution stimulates airway epithelial secretion through a cholinergic reflex that is unaffected in cystic fibrosis (CF), yet a strong correlation is observed between passive smoke exposure in the home and impaired lung function in CF children. Our aim was to study the effects of low smoke concentrations on cystic fibrosis transmembrane conductance regulator (CFTR) function in vitro. Cigarette smoke extract stimulated robust anion secretion that was transient, mediated by CFTR, and dependent on cAMP-dependent protein kinase activation...
January 1, 2018: American Journal of Physiology. Cell Physiology
Maria Talamo Guevara, Susanna A McColley
Lumacaftor-ivacaftor is indicated for treatment of cystic fibrosis (CF) in patients homozygous for the Phe-508del cystic fibrosis transmembrane conductance regulator (CFTR) gene mutations. In clinical trials, treated patients showed improved pulmonary function, reduced pulmonary exacerbations, and other benefits. This article reviews safety of this therapy. Areas covered: Safety findings in ivacaftor, lumacaftor and combined therapy trials, and reported subsequently through post-approval evaluation, were accessed by PubMed and Google searches using key words 'VX-770', 'ivacaftor', 'VX-809', and 'lumacaftor'...
November 2017: Expert Opinion on Drug Safety
Romina Fiorotto, Mariangela Amenduni, Valeria Mariotti, Luca Fabris, Carlo Spirli, Mario Strazzabosco
Cystic fibrosis transmembrane conductance regulator (CFTR), the channel mutated in cystic fibrosis (CF), is expressed by the biliary epithelium (i.e., cholangiocytes) of the liver. Progressive clinical liver disease (CF-associated liver disease; CFLD) occurs in around 10% of CF patients and represents the third leading cause of death. Impaired secretion and inflammation contribute to CFLD; however, the lack of human-derived experimental models has hampered the understanding of CFLD pathophysiology and the search for a cure...
March 2018: Hepatology: Official Journal of the American Association for the Study of Liver Diseases
Rhea P Hudson, Jennifer E Dawson, P Andrew Chong, Zhengrong Yang, Linda Millen, Philip J Thomas, Christie G Brouillette, Julie D Forman-Kay
Understanding the mechanism of action of modulator compounds for the cystic fibrosis transmembrane conductance regulator (CFTR) is key for the optimization of therapeutics as well as obtaining insights into the molecular mechanisms of CFTR function. We demonstrate the direct binding of VX-809 to the first nucleotide-binding domain (NBD1) of human CFTR. Disruption of the interaction between C-terminal helices and the NBD1 core upon VX-809 binding is observed from chemical shift changes in the NMR spectra of residues in the helices and on the surface of β-strands S3, S9, and S10...
August 2017: Molecular Pharmacology
Tip W Loo, David M Clarke
A large number of correctors have been identified that can partially repair defects in folding, stability and trafficking of CFTR processing mutants that cause cystic fibrosis (CF). The best corrector, VX-809 (Lumacaftor), has shown some promise when used in combination with a potentiator (Ivacaftor). Understanding the mechanism of VX-809 is essential for development of better correctors. Here, we tested our prediction that VX-809 repairs folding and processing defects of CFTR by promoting interactions between the first cytoplasmic loop (CL1) of transmembrane domain 1 (TMD1) and the first nucleotide-binding domain (NBD1)...
July 15, 2017: Biochemical Pharmacology
Carol A Bertrand, Shalini Mitra, Sanjay K Mishra, Xiaohui Wang, Yu Zhao, Joseph M Pilewski, Dean R Madden, Raymond A Frizzell
Several members of the SLC26A family of anion transporters associate with CFTR, forming complexes in which CFTR and SLC26A functions are reciprocally regulated. These associations are thought to be facilitated by PDZ scaffolding interactions. CFTR has been shown to be positively regulated by NHERF-1, and negatively regulated by CAL in airway epithelia. However, it is unclear which PDZ-domain protein(s) interact with SLC26A9, a SLC26A family member found in airway epithelia. We have previously shown that primary, human bronchial epithelia (HBE) from non-CF donors exhibit constitutive anion secretion attributable to SLC26A9...
June 1, 2017: American Journal of Physiology. Lung Cellular and Molecular Physiology
Verena Ihrig, Wolfgang M J Obermann
Deletion of a single phenylalanine residue at position 508 of the protein CFTR (cystic fibrosis transmembrane conductance regulator), a chloride channel in lung epithelium, is the most common cause for cystic fibrosis. As a consequence, folding of the CFTRΔF508 protein and delivery to the cell surface are compromised, resulting in degradation of the polypeptide. Accordingly, decreased surface presence of CFTRΔF508 causes impaired chloride ion conductivity and is associated with mucus accumulation, a hallmark of cystic fibrosis...
August 2017: SLAS Discovery
Zhihui Zhang, Michael M Baksh, M G Finn, David K Heidary, Christopher I Richards
Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) result in the disease cystic fibrosis. Deletion of Phe508, the most prevalent mutation associated with this disease, disrupts trafficking of the protein. Small molecule correctors yield moderate improvements in the trafficking of ΔF508-CFTR to the plasma membrane. It is currently not known if correctors increase the level of trafficking through improved cargo loading of transport vesicles or through direct binding to CFTR. Real-time measurements of trafficking were utilized to identify the mechanistic details of chemical, biochemical, and thermal factors that impact CFTR correction, using the corrector molecule VX-809, a secondary mutation (I539T), and low-temperature conditions...
January 10, 2017: Biochemistry
Martina Gentzsch, Susan E Boyles, Chaitra Cheluvaraju, Imron G Chaudhry, Nancy L Quinney, Crescentia Cho, Hong Dang, Xuefeng Liu, Richard Schlegel, Scott H Randell
Well-differentiated primary human bronchial epithelial (HBE) cell cultures are vital for cystic fibrosis (CF) research, particularly for the development of cystic fibrosis transmembrane conductance regulator (CFTR) modulator drugs. Culturing of epithelial cells with irradiated 3T3 fibroblast feeder cells plus the RhoA kinase inhibitor Y-27632 (Y), termed conditionally reprogrammed cell (CRC) technology, enhances cell growth and lifespan while preserving cell-of-origin functionality. We initially determined the electrophysiological and morphological characteristics of conventional versus CRC-expanded non-CF HBE cells...
May 2017: American Journal of Respiratory Cell and Molecular Biology
Peter M Haggie, Puay-Wah Phuan, Joseph-Anthony Tan, Haijin Xu, Radu G Avramescu, Doranda Perdomo, Lorna Zlock, Dennis W Nielson, Walter E Finkbeiner, Gergely L Lukacs, Alan S Verkman
W1282X is the fifth most common cystic fibrosis transmembrane regulator (CFTR) mutation that causes cystic fibrosis. Here, we investigated the utility of a small molecule corrector/potentiator strategy, as used for ΔF508-CFTR, to produce functional rescue of the truncated translation product of the W1282X mutation, CFTR1281 , without the need for read-through. In transfected cell systems, certain potentiators and correctors, including VX-809 and VX-770, increased CFTR1281 activity. To identify novel correctors and potentiators with potentially greater efficacy on CFTR1281 , functional screens were done of ∼30,000 synthetic small molecules and drugs/nutraceuticals in CFTR1281 -transfected cells...
January 20, 2017: Journal of Biological Chemistry
Onofrio Laselva, Steven Molinski, Valeria Casavola, Christine E Bear
Cystic Fibrosis (CF) is caused by mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene. The most common mutation, deletion of phenylalanine 508 (F508del), disrupts tertiary assembly, causing protein misprocessing and loss of CFTR function in epithelial tissues. Lumacaftor (VX-809) is a Class 1 corrector molecule shown to partially rescue misprocessing of F508del and together with the potentiator of channel activity: ivacaftor (VX-770) has been approved for treatment of CF patients homozygous for the F508del mutation...
November 1, 2016: Biochemical Pharmacology
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