title: Murine and human CFTR exhibit different sensitivities to CFTR potentiators.
abstract: Development of therapeutic molecules with clinical efficacy as modulators of defective CFTR includes efforts to identify potentiators that can overcome or repair the gating defect in mutant CFTR channels. This has taken a great leap forward with the identification of the potentiator VX-770, now available to patients as "Kalydeco." Other small molecules with different chemical structure also are capable of potentiating the activity of either wild-type or mutant CFTR, suggesting that there are features of the protein that may be targeted to achieve stimulation of channel activity by structurally diverse compounds. However, neither the mechanisms by which these compounds potentiate mutant CFTR nor the site(s) where these compounds bind have been identified. This knowledge gap partly reflects the lack of appropriate experimental models to provide clues toward the identification of binding sites. Here, we have compared the channel behavior and response to novel and known potentiators of human CFTR (hCFTR) and murine (mCFTR) expressed in Xenopus oocytes. Both hCFTR and mCFTR were blocked by GlyH-101 from the extracellular side, but mCFTR activity was increased with GlyH-101 applied directly to the cytoplasmic side. Similarly, glibenclamide only exhibited a blocking effect on hCFTR but both blocked and potentiated mCFTR in excised membrane patches and in intact oocytes. The clinically used CFTR potentiator VX-770 transiently increased hCFTR by ∼13% but potentiated mCFTR significantly more strongly. Our results suggest that mCFTR pharmacological sensitivities differ from hCFTR, which will provide a useful tool for identifying the binding sites and mechanism for these potentiators.
authors.affiliation: Division of Pulmonology, Allergy/Immunology, Cystic Fibrosis, and Sleep, Department of Pediatrics, Emory + Children's Center for Cystic Fibrosis and Airways Disease Research, Emory University School of Medicine and Children's Healthcare of Atlanta, Atlanta, Georgia.
authors.forename: Guiying
authors.initials: G
authors.lastname: Cui
authors.affiliation: Division of Pulmonology, Allergy/Immunology, Cystic Fibrosis, and Sleep, Department of Pediatrics, Emory + Children's Center for Cystic Fibrosis and Airways Disease Research, Emory University School of Medicine and Children's Healthcare of Atlanta, Atlanta, Georgia namccar@emory.edu.
authors.forename: Nael A
authors.initials: NA
authors.lastname: McCarty
mesh_terms: D000627:Aminophenols / Q000494:pharmacology*; D000818:Animals; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000819:agonists* / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D006801:Humans; D006834:Hydrazines / Q000494:pharmacology; D051379:Mice; D009865:Oocytes / Q000166:cytology / Q000378:metabolism; D015363:Quinolones / Q000494:pharmacology*; D013045:Species Specificity; D014982:Xenopus laevis
chemical_list: D000627:Aminophenols; C505032:CFTR protein, human; D006834:Hydrazines; C548779:N-(2-naphthalenyl)-((3,5-dibromo-2,4-dihydroxyphenyl)methylene)glycine hydrazide; D015363:Quinolones; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; C545203:ivacaftor; D005998:Glycine
keywords: blocker; human CFTR; murine CFTR; potentiator; single-channel recording