title: SERCA pump inhibitors do not correct biosynthetic arrest of deltaF508 CFTR in cystic fibrosis.
abstract: Deletion of phenylalanine 508 (deltaF508) accounts for nearly 70% of all mutations that occur in the cystic fibrosis transmembrane conductance regulator (CFTR). The deltaF508 mutation is a class II processing mutation that results in very little or no mature CFTR protein reaching the apical membrane and thus no cAMP-mediated Cl- conductance. Therapeutic strategies have been developed to enhance processing of the defective deltaF508 CFTR molecule so that a functional cAMP-regulated Cl- channel targets to the apical membrane. Sarcoplasmic/endoplasmic reticulum calcium (SERCA) inhibitors, curcumin and thapsigargin, have been reported to effectively correct the CF ion transport defects observed in the deltaF508 CF mice. We investigated the effect of these compounds in human airway epithelial cells to determine if they could induce deltaF508 CFTR maturation, and Cl- secretion. We also used Baby Hamster Kidney cells, heterologously expressing deltaF508 CFTR, to determine if SERCA inhibitors could interfere with the interaction between calnexin and CFTR and thereby correct the deltaF508 CFTR misfolding defect. Finally, at the whole animal level, we tested the ability of curcumin and thapsigargin to (1) induce Cl- secretion and reduce hyperabsorption of Na+ in the nasal epithelia of the deltaF508 mouse in vivo, and (2) induce Cl- secretion in intestine (jejunum and distal colon) and the gallbladder of the deltaF508 CF mouse. We conclude that curcumin and thapsigargin failed to induce maturation of deltaF508 CFTR, or induce Cl- secretion, as measured by biochemical and electrophysiologic techniques in a variety of model systems ranging from cultured cells to in vivo studies.
authors.affiliation: Cystic Fibrosis/Pulmonary Research and Treatment Center, 7011 Thurston-Bowles Bldg., CB# 7248, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7248, USA. bgrubb@med.unc.edu
authors.forename: Barbara R
authors.initials: BR
authors.lastname: Grubb
authors.forename: Sherif E
authors.initials: SE
authors.lastname: Gabriel
authors.forename: April
authors.initials: A
authors.lastname: Mengos
authors.forename: Martina
authors.initials: M
authors.lastname: Gentzsch
authors.forename: Scott H
authors.initials: SH
authors.lastname: Randell
authors.forename: Anna M
authors.initials: AM
authors.lastname: Van Heeckeren
authors.forename: Michael R
authors.initials: MR
authors.lastname: Knowles
authors.forename: Mitchell L
authors.initials: ML
authors.lastname: Drumm
authors.forename: John R
authors.initials: JR
authors.lastname: Riordan
authors.forename: Richard C
authors.initials: RC
authors.lastname: Boucher
mesh_terms: D000818:Animals; D001980:Bronchi / Q000166:cytology; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors*; D037281:Calnexin / Q000378:metabolism; D002478:Cells, Cultured; D002712:Chlorides / Q000378:metabolism; D006224:Cricetinae; D003474:Curcumin / Q000494:pharmacology*; D003550:Cystic Fibrosis / Q000378:metabolism*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000096:biosynthesis* / Q000235:genetics; D005704:Gallbladder / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007422:Intestines / Q000187:drug effects / Q000502:physiology; D017136:Ion Transport; D051379:Mice; D008817:Mice, Mutant Strains; D009154:Mutation; D017510:Protein Folding; D020545:Respiratory Mucosa / Q000187:drug effects* / Q000378:metabolism; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D012964:Sodium / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology*
chemical_list: D002712:Chlorides; C093349:cystic fibrosis transmembrane conductance regulator delta F508; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D037281:Calnexin; D019284:Thapsigargin; D012964:Sodium; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D000252:Calcium-Transporting ATPases; D003474:Curcumin