title: Robust Stimulation of W1282X-CFTR Channel Activity by a Combination of Allosteric Modulators.
abstract: W1282X is a common nonsense mutation among cystic fibrosis patients that results in the production of a truncated Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) channel. Here we show that the channel activity of the W1282X-CFTR polypeptide is exceptionally low in excised membrane patches at normally saturating doses of ATP and PKA (single channel open probability (PO) < 0.01). However, W1282X-CFTR channels were stimulated by two CFTR modulators, the FDA-approved VX-770 and the dietary compound curcumin. Each of these compounds is an allosteric modulator of CFTR gating that promotes channel activity in the absence of the native ligand, ATP. Although W1282X-CFTR channels were stimulated by VX-770 in the absence of ATP their activities remained dependent on PKA phosphorylation. Thus, activated W1282X-CFTR channels should remain under physiologic control by cyclic nucleotide signaling pathways in vivo. VX-770 and curcumin exerted additive effects on W1282X-CFTR channel gating (opening/closing) in excised patches such that the Po of the truncated channel approached unity (> 0.9) when treated with both modulators. VX-770 and curcumin also additively stimulated W1282X-CFTR mediated currents in polarized FRT epithelial monolayers. In this setting, however, the stimulated W1282X-CFTR currents were smaller than those mediated by wild type CFTR (3-5%) due presumably to lower expression levels or cell surface targeting of the truncated protein. Combining allosteric modulators of different mechanistic classes is worth considering as a treatment option for W1282X CF patients perhaps when coupled with maneuvers to increase expression of the truncated protein.
authors.affiliation: Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL, 35294, United States of America.|Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, 35294, United States of America.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL, 35294, United States of America.|Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, 35294, United States of America.
authors.forename: Jeong S
authors.initials: JS
authors.lastname: Hong
authors.affiliation: Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL, 35294, United States of America.
authors.forename: Andras
authors.initials: A
authors.lastname: Rab
authors.affiliation: Department of Pediatrics, Emory University, Atlanta, GA, 30322, United States of America.
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Sorscher
authors.affiliation: Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL, 35294, United States of America.|Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, 35294, United States of America.
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Kirk
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000494:Allosteric Regulation / Q000187:drug effects; D000627:Aminophenols / Q000494:pharmacology; D018389:Codon, Nonsense / Q000235:genetics / Q000502:physiology; D003474:Curcumin / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000819:agonists / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D057809:HEK293 Cells; D006801:Humans; D018408:Patch-Clamp Techniques; D010766:Phosphorylation; D015363:Quinolones / Q000494:pharmacology
chemical_list: D000627:Aminophenols; D018389:Codon, Nonsense; D015363:Quinolones; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; C545203:ivacaftor; D000255:Adenosine Triphosphate; D017868:Cyclic AMP-Dependent Protein Kinases; D003474:Curcumin