CFTR: folding, misfolding and correcting the ΔF508 conformational defect.

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.

[1]  David Y. Thomas,et al.  Identification of a NBD1-binding pharmacological chaperone that corrects the trafficking defect of F508del-CFTR. , 2011, Chemistry & biology.

[2]  R. Morimoto,et al.  Biological and chemical approaches to diseases of proteostasis deficiency. , 2009, Annual review of biochemistry.

[3]  Bart Kus,et al.  Correction of the ΔPhe508 Cystic Fibrosis Transmembrane Conductance Regulator Trafficking Defect by the Bioavailable Compound Glafenine , 2010, Molecular Pharmacology.

[4]  T. Ma,et al.  Nanomolar Affinity Small Molecule Correctors of Defective ΔF508-CFTR Chloride Channel Gating* , 2003, Journal of Biological Chemistry.

[5]  Mark J. Kurth,et al.  Potent s-cis-locked bithiazole correctors of DeltaF508 cystic fibrosis transmembrane conductance regulator cellular processing for cystic fibrosis therapy. , 2008, Journal of medicinal chemistry.

[6]  M. Goossens,et al.  COMMD1-Mediated Ubiquitination Regulates CFTR Trafficking , 2011, PloS one.

[7]  Gianluca Damonte,et al.  Dual Activity of Aminoarylthiazoles on the Trafficking and Gating Defects of the Cystic Fibrosis Transmembrane Conductance Regulator Chloride Channel Caused by Cystic Fibrosis Mutations* , 2011, The Journal of Biological Chemistry.

[8]  S Grinstein,et al.  The delta F508 mutation decreases the stability of cystic fibrosis transmembrane conductance regulator in the plasma membrane. Determination of functional half-lives on transfected cells. , 1993, The Journal of biological chemistry.

[9]  R. Kopito,et al.  Intracellular turnover of cystic fibrosis transmembrane conductance regulator. Inefficient processing and rapid degradation of wild-type and mutant proteins. , 1994, The Journal of biological chemistry.

[10]  D. Sheppard,et al.  Targeting F508del-CFTR to develop rational new therapies for cystic fibrosis , 2011, Acta Pharmacologica Sinica.

[11]  Adrian W. R. Serohijos,et al.  Phenylalanine-508 mediates a cytoplasmic–membrane domain contact in the CFTR 3D structure crucial to assembly and channel function , 2008, Proceedings of the National Academy of Sciences.

[12]  N. Vij,et al.  Ubiquitin C-terminal Hydrolase-L1 Protects Cystic Fibrosis Transmembrane Conductance Regulator from Early Stages of Proteasomal Degradation* , 2010, The Journal of Biological Chemistry.

[13]  J. Riordan,et al.  Modulation of endocytic trafficking and apical stability of CFTR in primary human airway epithelial cultures. , 2010, American journal of physiology. Lung cellular and molecular physiology.

[14]  Zhengrong Yang,et al.  Integrated biophysical studies implicate partial unfolding of NBD1 of CFTR in the molecular pathogenesis of F508del cystic fibrosis , 2010, Protein science : a publication of the Protein Society.

[15]  K. Lindsten,et al.  The ER‐resident ubiquitin‐specific protease 19 participates in the UPR and rescues ERAD substrates , 2009, EMBO reports.

[16]  W. Skach,et al.  Ligand-driven vectorial folding of ribosome-bound human CFTR NBD1. , 2011, Molecular cell.

[17]  J. M. Sauder,et al.  Impact of the ΔF508 Mutation in First Nucleotide-binding Domain of Human Cystic Fibrosis Transmembrane Conductance Regulator on Domain Folding and Structure* , 2005, Journal of Biological Chemistry.

[18]  Design and synthesis of a hybrid potentiator-corrector agonist of the cystic fibrosis mutant protein DeltaF508-CFTR. , 2010, Bioorganic & medicinal chemistry letters.

[19]  P. Negulescu,et al.  Correction of the F508del-CFTR protein processing defect in vitro by the investigational drug VX-809 , 2011, Proceedings of the National Academy of Sciences.

[20]  J. Riordan,et al.  Assembly of functional CFTR chloride channels. , 2005, Annual review of physiology.

[21]  J. Wakefield,et al.  Efficient Intracellular Processing of the Endogenous Cystic Fibrosis Transmembrane Conductance Regulator in Epithelial Cell Lines* , 2004, Journal of Biological Chemistry.

[22]  Kai Du,et al.  Cooperative assembly and misfolding of CFTR domains in vivo. , 2009, Molecular biology of the cell.

[23]  Christine E. Bear,et al.  A Chemical Corrector Modifies the Channel Function of F508del-CFTR , 2010, Molecular Pharmacology.

[24]  S. Matalon,et al.  Functional stability of rescued delta F508 cystic fibrosis transmembrane conductance regulator in airway epithelial cells. , 2010, American journal of respiratory cell and molecular biology.

[25]  Ying Wang,et al.  Correctors Promote Maturation of Cystic Fibrosis Transmembrane Conductance Regulator (CFTR)-processing Mutants by Binding to the Protein* , 2007, Journal of Biological Chemistry.

[26]  J. Riordan,et al.  CFTR function and prospects for therapy. , 2008, Annual review of biochemistry.

[27]  John F Hunt,et al.  Structures of a minimal human CFTR first nucleotide-binding domain as a monomer, head-to-tail homodimer, and pathogenic mutant. , 2010, Protein engineering, design & selection : PEDS.

[28]  H. Kawasaki,et al.  E3 ubiquitin ligase that recognizes sugar chains , 2002, Nature.

[29]  Philip J. Thomas,et al.  The Primary Folding Defect and Rescue of ΔF508 CFTR Emerge during Translation of the Mutant Domain , 2010, PloS one.

[30]  S. Matalon,et al.  Enhanced cell-surface stability of rescued DeltaF508 cystic fibrosis transmembrane conductance regulator (CFTR) by pharmacological chaperones. , 2008, The Biochemical journal.

[31]  G. Lukács,et al.  Conformational and Temperature-sensitive Stability Defects of the ΔF508 Cystic Fibrosis Transmembrane Conductance Regulator in Post-endoplasmic Reticulum Compartments* , 2001, The Journal of Biological Chemistry.

[32]  G. Lukács,et al.  Protein quality control at the plasma membrane. , 2011, Current opinion in cell biology.

[33]  Nikolay V. Dokholyan,et al.  Diminished Self-Chaperoning Activity of the ΔF508 Mutant of CFTR Results in Protein Misfolding , 2008, PLoS Comput. Biol..

[34]  P. Negulescu,et al.  Rescue of the protein folding defect in cystic fibrosis in vitro by the investigational small molecule, VX-809 , 2010 .

[35]  S. Teichmann,et al.  The folding and evolution of multidomain proteins , 2007, Nature Reviews Molecular Cell Biology.

[36]  Zhengrong Yang,et al.  Thermal unfolding studies show the disease causing F508del mutation in CFTR thermodynamically destabilizes nucleotide‐binding domain 1 , 2010, Protein science : a publication of the Protein Society.

[37]  Donglei Zhang,et al.  Correctors of Protein Trafficking Defects Identified by a Novel High‐Throughput Screening Assay , 2007, Chembiochem : a European journal of chemical biology.

[38]  M. Wilke,et al.  Parallel Improvement of Sodium and Chloride Transport Defects by Miglustat (n-Butyldeoxynojyrimicin) in Cystic Fibrosis Epithelial Cells , 2008, Journal of Pharmacology and Experimental Therapeutics.

[39]  John D. Venable,et al.  Hsp90 Cochaperone Aha1 Downregulation Rescues Misfolding of CFTR in Cystic Fibrosis , 2006, Cell.

[40]  C. Fan,et al.  A foldable CFTRΔF508 biogenic intermediate accumulates upon inhibition of the Hsc70–CHIP E3 ubiquitin ligase , 2004, The Journal of cell biology.

[41]  Harvey B Pollard,et al.  Rescue of ΔF508-CFTR by the SGK1/Nedd4-2 Signaling Pathway* , 2009, The Journal of Biological Chemistry.

[42]  T. Hwang,et al.  The most common cystic fibrosis‐associated mutation destabilizes the dimeric state of the nucleotide‐binding domains of CFTR , 2011, The Journal of physiology.

[43]  N. Bradbury,et al.  A Mutation in the Cystic Fibrosis Transmembrane Conductance Regulator Generates a Novel Internalization Sequence and Enhances Endocytic Rates* , 2003, The Journal of Biological Chemistry.

[44]  J. Marshall,et al.  Defective intracellular transport and processing of CFTR is the molecular basis of most cystic fibrosis , 1990, Cell.

[45]  John M. Knapp,et al.  Cyanoquinolines with Independent Corrector and Potentiator Activities Restore ΔPhe508-Cystic Fibrosis Transmembrane Conductance Regulator Chloride Channel Function in Cystic Fibrosis , 2011, Molecular Pharmacology.

[46]  A S Verkman,et al.  Pyrazolylthiazole as DeltaF508-cystic fibrosis transmembrane conductance regulator correctors with improved hydrophilicity compared to bithiazoles. , 2010, Journal of medicinal chemistry.

[47]  Kai Du,et al.  Small-molecule correctors of defective DeltaF508-CFTR cellular processing identified by high-throughput screening. , 2005, The Journal of clinical investigation.

[48]  Kenneth L. Nesbitt,et al.  Restoration of domain folding and interdomain assembly by second‐site suppressors of the ΔF508 mutation in CFTR , 2010, FASEB journal : official publication of the Federation of American Societies for Experimental Biology.

[49]  D. Cyr,et al.  Mechanisms for rescue of correctable folding defects in CFTRDelta F508. , 2009, Molecular biology of the cell.

[50]  Keiji Tanaka,et al.  Gp78 cooperates with RMA1 in endoplasmic reticulum-associated degradation of CFTRDeltaF508. , 2008, Molecular biology of the cell.

[51]  J. Riordan,et al.  F508del CFTR with two altered RXR motifs escapes from ER quality control but its channel activity is thermally sensitive. , 2006, Biochimica et biophysica acta.

[52]  J. Clancy,et al.  Effect of VX-770 in persons with cystic fibrosis and the G551D-CFTR mutation. , 2010, The New England journal of medicine.

[53]  K. Du,et al.  Curcumin, a Major Constituent of Turmeric, Corrects Cystic Fibrosis Defects , 2004, Science.

[54]  J. Brodsky,et al.  Protein folding and quality control in the endoplasmic reticulum: Recent lessons from yeast and mammalian cell systems. , 2011, Current opinion in cell biology.

[55]  Pascal Barbry,et al.  Altered chloride ion channel kinetics associated with the ΔF508 cystic fibrosis mutation , 1991, Nature.

[56]  Nicoletta Pedemonte,et al.  Phenylglycine and Sulfonamide Correctors of Defective ΔF508 and G551D Cystic Fibrosis Transmembrane Conductance Regulator Chloride-Channel Gating , 2005, Molecular Pharmacology.

[57]  Paola Vergani,et al.  CFTR channel opening by ATP-driven tight dimerization of its nucleotide-binding domains , 2005, Nature.

[58]  Jinglan Zhou,et al.  Rescue of CF airway epithelial cell function in vitro by a CFTR potentiator, VX-770 , 2009, Proceedings of the National Academy of Sciences.

[59]  Wei Wang,et al.  A Unified View of Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Gating: Combining the Allosterism of a Ligand-gated Channel with the Enzymatic Activity of an ATP-binding Cassette (ABC) Transporter* , 2011, The Journal of Biological Chemistry.

[60]  D. Cyr,et al.  Assembly and misassembly of cystic fibrosis transmembrane conductance regulator: folding defects caused by deletion of F508 occur before and after the calnexin-dependent association of membrane spanning domain (MSD) 1 and MSD2. , 2008, Molecular biology of the cell.

[61]  D. Clarke,et al.  Correctors promote folding of the CFTR in the endoplasmic reticulum. , 2008, The Biochemical journal.

[62]  D. Clarke,et al.  Correctors enhance maturation of DeltaF508 CFTR by promoting interactions between the two halves of the molecule. , 2009, Biochemistry.

[63]  A W Cuthbert,et al.  New horizons in the treatment of cystic fibrosis , 2011, British journal of pharmacology.

[64]  D. Clarke,et al.  Processing Mutations Disrupt Interactions between the Nucleotide Binding and Transmembrane Domains of P-glycoprotein and the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR)* , 2008, Journal of Biological Chemistry.

[65]  M. Amaral,et al.  Solubilizing mutations used to crystallize one CFTR domain attenuate the trafficking and channel defects caused by the major cystic fibrosis mutation. , 2008, Chemistry & biology.

[66]  C. Fan,et al.  The endoplasmic reticulum–associated Hsp40 DNAJB12 and Hsc70 cooperate to facilitate RMA1 E3–dependent degradation of nascent CFTRΔF508 , 2010, Molecular biology of the cell.

[67]  Andrei Aleksandrov,et al.  Domain interdependence in the biosynthetic assembly of CFTR. , 2007, Journal of molecular biology.

[68]  James Rader,et al.  Rescue of DeltaF508-CFTR trafficking and gating in human cystic fibrosis airway primary cultures by small molecules. , 2006, American journal of physiology. Lung cellular and molecular physiology.

[69]  B. Papsin,et al.  Misfolding diverts CFTR from recycling to degradation , 2004, The Journal of cell biology.

[70]  E. Olson,et al.  Therapeutics development for cystic fibrosis: a successful model for a multisystem genetic disease. , 2011, Annual review of medicine.

[71]  G. Lukács,et al.  N-glycans are direct determinants of CFTR folding and stability in secretory and endocytic membrane traffic , 2009, The Journal of cell biology.

[72]  J. Mornon,et al.  Atomic model of human cystic fibrosis transmembrane conductance regulator: Membrane-spanning domains and coupling interfaces , 2008, Cellular and Molecular Life Sciences.

[73]  Vicky A Legrys,et al.  Guidelines for diagnosis of cystic fibrosis in newborns through older adults: Cystic Fibrosis Foundation consensus report. , 2008, The Journal of pediatrics.

[74]  Nikolay V. Dokholyan,et al.  Multiple Membrane-Cytoplasmic Domain Contacts in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Mediate Regulation of Channel Gating* , 2008, Journal of Biological Chemistry.

[75]  S Grinstein,et al.  Conformational maturation of CFTR but not its mutant counterpart (delta F508) occurs in the endoplasmic reticulum and requires ATP. , 1994, The EMBO journal.

[76]  D. Clarke,et al.  The V510D Suppressor Mutation Stabilizes ΔF508-CFTR at the Cell Surface† , 2010, Biochemistry.

[77]  Kai Du,et al.  The ΔF508 cystic fibrosis mutation impairs domain-domain interactions and arrests post-translational folding of CFTR , 2005, Nature Structural &Molecular Biology.

[78]  P. Zielenkiewicz,et al.  DeltaF508 mutation increases conformational flexibility of CFTR protein. , 2008, Journal of cystic fibrosis : official journal of the European Cystic Fibrosis Society.

[79]  Donglei Zhang,et al.  Structural Analog of Sildenafil Identified as a Novel Corrector of the F508del-CFTR Trafficking Defect , 2008, Molecular Pharmacology.

[80]  F. Collins,et al.  Chloride conductance expressed by delta F508 and other mutant CFTRs in Xenopus oocytes. , 1991, Science.

[81]  Jason C. Young,et al.  Peripheral Protein Quality Control Removes Unfolded CFTR from the Plasma Membrane , 2010, Science.

[82]  M. Boyle,et al.  Evidence of CFTR function in cystic fibrosis after systemic administration of 4-phenylbutyrate. , 2002, Molecular therapy : the journal of the American Society of Gene Therapy.

[83]  Paola Bisignano,et al.  Molecular dynamics analysis of the wild type and dF508 mutant structures of the human CFTR-nucleotide binding domain 1. , 2010, Biochimie.

[84]  D. Stolz,et al.  c-Cbl Facilitates Endocytosis and Lysosomal Degradation of Cystic Fibrosis Transmembrane Conductance Regulator in Human Airway Epithelial Cells* , 2010, The Journal of Biological Chemistry.

[85]  John R. Yates,et al.  Chemical and Biological Approaches Synergize to Ameliorate Protein-Folding Diseases , 2008, Cell.

[86]  W. Balch,et al.  Emergent properties of proteostasis in managing cystic fibrosis. , 2011, Cold Spring Harbor perspectives in biology.

[87]  Chad A Brautigam,et al.  Side chain and backbone contributions of Phe508 to CFTR folding , 2005, Nature Structural &Molecular Biology.

[88]  J. Bomberger,et al.  The Deubiquitinating Enzyme USP10 Regulates the Post-endocytic Sorting of Cystic Fibrosis Transmembrane Conductance Regulator in Airway Epithelial Cells* , 2009, The Journal of Biological Chemistry.

[89]  Efrat Ben-Zeev,et al.  Small molecule correctors of F508del-CFTR discovered by structure-based virtual screening , 2010, J. Comput. Aided Mol. Des..

[90]  Satoshi Omura,et al.  Degradation of CFTR by the ubiquitin-proteasome pathway , 1995, Cell.

[91]  Isabelle Callebaut,et al.  Molecular models of the open and closed states of the whole human CFTR protein , 2009, Cellular and Molecular Life Sciences.

[92]  C. Fan,et al.  Sequential Quality-Control Checkpoints Triage Misfolded Cystic Fibrosis Transmembrane Conductance Regulator , 2006, Cell.

[93]  Matthew P. Anderson,et al.  Processing of mutant cystic fibrosis transmembrane conductance regulator is temperature-sensitive , 1992, Nature.

[94]  P. Thomas,et al.  Alteration of the Cystic Fibrosis Transmembrane Conductance Regulator Folding Pathway , 1996, The Journal of Biological Chemistry.

[95]  D. Cyr,et al.  The Hsc70 co-chaperone CHIP targets immature CFTR for proteasomal degradation , 2000, Nature Cell Biology.

[96]  John R Yates,et al.  Reduced histone deacetylase 7 activity restores function to misfolded CFTR in cystic fibrosis. , 2010, Nature chemical biology.

[97]  J. M. Sauder,et al.  Structure and dynamics of NBD1 from CFTR characterized using crystallography and hydrogen/deuterium exchange mass spectrometry. , 2010, Journal of molecular biology.

[98]  H. Senderowitz,et al.  The Cystic Fibrosis-causing Mutation ΔF508 Affects Multiple Steps in Cystic Fibrosis Transmembrane Conductance Regulator Biogenesis* , 2010, The Journal of Biological Chemistry.

[99]  I. Braakman,et al.  Folding of CFTR is predominantly cotranslational. , 2005, Molecular cell.