title: Mutation-specific potency and efficacy of cystic fibrosis transmembrane conductance regulator chloride channel potentiators.
abstract: Cystic fibrosis (CF) is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel. The mutations G551D and G1349D, which affect the nucleotide-binding domains (NBDs) of CFTR protein, reduce channel activity. This defect can be corrected pharmacologically by small molecules called potentiators. CF mutations residing in the intracellular loops (ICLs), connecting the transmembrane segments of CFTR, may also reduce channel activity. We have investigated the extent of loss of function caused by ICL mutations and the sensitivity to pharmacological stimulation. We found that E193K and G970R (in ICL1 and ICL3, respectively) cause a severe loss of CFTR channel activity that can be rescued by the same potentiators that are effective on NBD mutations. We compared potency and efficacy of three different potentiators for E193K, G970R, and G551D. The 1,4-dihydropyridine felodipine and the phenylglycine PG-01 [2-[(2-1H-indol-3-yl-acetyl)-methylamino]-N-(4-isopropylphenyl)-2-phenylacetamide] were strongly effective on the three CFTR mutants. The efficacy of sulfonamide SF-01 [6-(ethylphenylsulfamoyl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid cycloheptylamide], another CFTR potentiator, was instead significantly lower than felodipine and PG-01 for the E193K and G970R mutations, and almost abolished for G551D. Furthermore, SF-01 modified the response of G551D and G970R to the other two potentiators, an effect that may be explained by an allosteric antagonistic effect. Our results indicate that CFTR potentiators correct the basic defect caused by CF mutations residing in different CFTR domains. However, there are differences among potentiators, with felodipine and PG-01 having a wider pharmacological activity, and SF-01 being more mutation specific. Our observations are useful in the prioritization and development of drugs targeting the CF basic defect.
authors.affiliation: Laboratorio di Genetica Molecolare, Istituto Giannna Gaslini, Largo Gerolamo Gaslini 5, 16147 Genova, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Caputo
authors.forename: Alexandre
authors.initials: A
authors.lastname: Hinzpeter
authors.forename: Emanuela
authors.initials: E
authors.lastname: Caci
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Pedemonte
authors.forename: Nicole
authors.initials: N
authors.lastname: Arous
authors.forename: Marco
authors.initials: M
authors.lastname: Di Duca
authors.forename: Olga
authors.initials: O
authors.lastname: Zegarra-Moran
authors.forename: Pascale
authors.initials: P
authors.lastname: Fanen
authors.forename: Luis J V
authors.initials: LJ
authors.lastname: Galietta
mesh_terms: D000465:Algorithms; D000818:Animals; D001665:Binding Sites; D015153:Blotting, Western; D019556:COS Cells; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002522:Chlorocebus aethiops; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000819:agonists* / Q000235:genetics*; D004305:Dose-Response Relationship, Drug; D024202:Electrophoretic Mobility Shift Assay; D015736:Felodipine / Q000494:pharmacology; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D016296:Mutagenesis; D009154:Mutation / Q000502:physiology; D014162:Transfection
chemical_list: D002121:Calcium Channel Blockers; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; C008852:2-phenylglycine; D015736:Felodipine; D005998:Glycine