title: A PDZ-interacting domain in CFTR is an apical membrane polarization signal.
abstract: Polarization of the cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-activated chloride channel, to the apical plasma membrane of epithelial cells is critical for vectorial transport of chloride in a variety of epithelia, including the airway, pancreas, intestine, and kidney. However, the motifs that localize CFTR to the apical membrane are unknown. We report that the last 3 amino acids in the COOH-terminus of CFTR (T-R-L) comprise a PDZ-interacting domain that is required for the polarization of CFTR to the apical plasma membrane in human airway and kidney epithelial cells. In addition, the CFTR mutant, S1455X, which lacks the 26 COOH-terminal amino acids, including the PDZ-interacting domain, is mispolarized to the lateral membrane. We also demonstrate that CFTR binds to ezrin-radixin-moesin-binding phosphoprotein 50 (EBP50), an apical membrane PDZ domain-containing protein. We propose that COOH-terminal deletions of CFTR, which represent about 10% of CFTR mutations, result in defective vectorial chloride transport, partly by altering the polarized distribution of CFTR in epithelial cells. Moreover, our data demonstrate that PDZ-interacting domains and PDZ domain-containing proteins play a key role in the apical polarization of ion channels in epithelial cells.
authors.affiliation: Department of Physiology, Dartmouth Medical School, Hanover, New Hampshire 03755, USA.
authors.forename: B D
authors.initials: BD
authors.lastname: Moyer
authors.forename: J
authors.initials: J
authors.lastname: Denton
authors.forename: K H
authors.initials: KH
authors.lastname: Karlson
authors.forename: D
authors.initials: D
authors.lastname: Reynolds
authors.forename: S
authors.initials: S
authors.lastname: Wang
authors.forename: J E
authors.initials: JE
authors.lastname: Mickle
authors.forename: M
authors.initials: M
authors.lastname: Milewski
authors.forename: G R
authors.initials: GR
authors.lastname: Cutting
authors.forename: W B
authors.initials: WB
authors.lastname: Guggino
authors.forename: M
authors.initials: M
authors.lastname: Li
authors.forename: B A
authors.initials: BA
authors.lastname: Stanton
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology*; D002712:Chlorides / Q000378:metabolism; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000737:chemistry* / Q000378:metabolism*; D004285:Dogs; D004847:Epithelial Cells / Q000502:physiology; D006801:Humans; D008565:Membrane Proteins / Q000032:analysis / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D010569:Perylene; D010750:Phosphoproteins / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D017384:Sequence Deletion; D015398:Signal Transduction; D017923:Sodium-Hydrogen Exchangers; D014162:Transfection; D062826:Zonula Occludens-1 Protein
chemical_list: C505032:CFTR protein, human; D002352:Carrier Proteins; D002712:Chlorides; D008565:Membrane Proteins; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; D017923:Sodium-Hydrogen Exchangers; C569042:TJP1 protein, human; D062826:Zonula Occludens-1 Protein; C093376:sodium-hydrogen exchanger regulatory factor; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D010569:Perylene