Plasma membrane CFTR regulates RANTES expression via its C-terminal PDZ-interacting motif.
Despite the identification of 1,000 mutations in the cystic fibrosis gene product CFTR, there remains discordance between CFTR genotype and lung disease phenotype. The study of CFTR, therefore, has expanded beyond its chloride channel activity into other possible functions, such as its role as a regulator of gene expression. Findings indicate that CFTR plays a role in the expression of RANTES in airway epithelia. RANTES is a chemokine that has been implicated in the regulation of mucosal immunity and the pathogenesis of airway inflammatory diseases. Results demonstrate that CFTR triggers RANTES expression via a mechanism that is independent of CFTR's chloride channel activity. Neither pharmacological inhibition of CFTR nor activation of alternative chloride channels, including hClC-2, modulated RANTES expression. Through the use of CFTR disease-associated and truncation mutants, experiments suggest that CFTR-mediated transcription factor activation and RANTES expression require (i) insertion of CFTR into the plasma membrane and (ii) an intact CFTR C-terminal PDZ-interacting domain. Expression of constructs encoding wild-type or dominant-negative forms of the PDZ-binding protein EBP50 suggests that EBP50 may be involved in CFTR-dependent RANTES expression. Together, these data suggest that CFTR modulates gene expression in airway epithelial cells while located in a macromolecular signaling complex at the plasma membrane.
Estell
Kim
K
Department of Physiology and Biophysics. The Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
Braunstein
Gavin
G
Tucker
Torry
T
Varga
Karoly
K
Collawn
James F
JF
Schwiebert
Lisa M
LM
D020816:Amino Acid Motifs; D001667:Binding, Competitive; D001692:Biological Transport; D019921:Biotinylation; D001980:Bronchi / Q000378:metabolism; D002087:Butyrates / Q000494:pharmacology; D002352:Carrier Proteins / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D018946:Chemokine CCL5 / Q000096:biosynthesis* / Q000737:chemistry; D002712:Chlorides / Q000378:metabolism; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000737:chemistry / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000473:pathology; D006801:Humans; D015151:Immunoblotting; D009154:Mutation; D016328:NF-kappa B / Q000378:metabolism; D010641:Phenotype; D010750:Phosphoproteins / Q000378:metabolism; D011233:Precipitin Tests; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017923:Sodium-Hydrogen Exchangers; D013997:Time Factors; D014158:Transcription, Genetic; D014162:Transfection
D002087:Butyrates; C505032:CFTR protein, human; D002352:Carrier Proteins; D018946:Chemokine CCL5; D002712:Chlorides; D016328:NF-kappa B; D010750:Phosphoproteins; D017923:Sodium-Hydrogen Exchangers; C093376:sodium-hydrogen exchanger regulatory factor; D019005:Cystic Fibrosis Transmembrane Conductance Regulator