title: Phenylglycine and sulfonamide correctors of defective delta F508 and G551D cystic fibrosis transmembrane conductance regulator chloride-channel gating.
abstract: Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel cause cystic fibrosis. The delta F508 mutation produces defects in channel gating and cellular processing, whereas the G551D mutation produces primarily a gating defect. To identify correctors of gating, 50,000 diverse small molecules were screened at 2.5 microM (with forskolin, 20 microM) by an iodide uptake assay in epithelial cells coexpressing delta F508-CFTR and a fluorescent halide indicator (yellow fluorescent protein-H148Q/I152L) after delta F508-CFTR rescue by 24-h culture at 27 degrees C. Secondary analysis and testing of >1000 structural analogs yielded two novel classes of correctors of defective delta F508-CFTR gating ("potentiators") with nanomolar potency that were active in human delta F508 and G551D cells. The most potent compound of the phenylglycine class, 2-[(2-1H-indol-3-yl-acetyl)-methylamino]-N-(4-isopropylphenyl)-2-phenylacetamide, reversibly activated delta F508-CFTR in the presence of forskolin with K(a) approximately 70 nM and also activated the CFTR gating mutants G551D and G1349D with K(a) values of approximately 1100 and 40 nM, respectively. The most potent sulfonamide, 6-(ethylphenylsulfamoyl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid cycloheptylamide, had K(a) approximately 20 nM for activation of delta F508-CFTR. In cell-attached patch-clamp experiments, phenylglycine-01 (PG-01) and sulfonamide-01 (SF-01) increased channel open probability >5-fold by the reduction of interburst closed time. An interesting property of these compounds was their ability to act in synergy with cAMP agonists. Microsome metabolism studies and rat pharmacokinetic analysis suggested significantly more rapid metabolism of PG-01 than SF-03. Phenylglycine and sulfonamide compounds may be useful for monotherapy of cystic fibrosis caused by gating mutants and possibly for a subset of delta F508 subjects with significant delta F508-CFTR plasma-membrane expression.
authors.affiliation: Department of Medicine, University of California, San Francisco, 94143-0521, USA.
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Pedemonte
authors.forename: N D
authors.initials: ND
authors.lastname: Sonawane
authors.forename: Alessandro
authors.initials: A
authors.lastname: Taddei
authors.forename: Jie
authors.initials: J
authors.lastname: Hu
authors.forename: Olga
authors.initials: O
authors.lastname: Zegarra-Moran
authors.forename: Yat Fan
authors.initials: YF
authors.lastname: Suen
authors.forename: Lori I
authors.initials: LI
authors.lastname: Robins
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Dicus
authors.forename: Dan
authors.initials: D
authors.lastname: Willenbring
authors.forename: Michael H
authors.initials: MH
authors.lastname: Nantz
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Kurth
authors.forename: Luis J V
authors.initials: LJ
authors.lastname: Galietta
authors.forename: A S
authors.initials: AS
authors.lastname: Verkman
mesh_terms: D000818:Animals; D018118:Chloride Channels / Q000235:genetics / Q000378:metabolism*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology*; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D011916:Rats, Inbred F344; D013449:Sulfonamides / Q000737:chemistry / Q000494:pharmacology*
chemical_list: C505032:CFTR protein, human; D018118:Chloride Channels; D013449:Sulfonamides; C093349:cystic fibrosis transmembrane conductance regulator delta F508; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D005998:Glycine