Role of CFTR's PDZ1-binding domain, NBF1 and Cl(-) conductance in inhibition of epithelial Na(+) channels in Xenopus oocytes.
The cystic fibrosis transmembrane conductance regulator (CFTR) inhibits epithelial Na(+) channels (ENaC). Evidence has accumulated that both Cl(-) transport through CFTR Cl(-) channels and the first nucleotide binding domain (NBF1) of CFTR are crucial for inhibition of ENaC. A PDZ binding domain (PDZ-BD) at the C-terminal end links CFTR to scaffolding and cytoskeletal proteins, which have been suggested to play an important role in activation of CFTR and eventually inhibition of ENaC. We eliminated the PDZ-BD of CFTR and coexpressed Na(+)/H(+)-exchange regulator factors together with CFTR and ENaC. The results do not support a role of PDZ-BD in inhibition of ENaC by CFTR. However, inhibition of ENaC was closely linked to Cl(-) currents generated by CFTR and was observed in the presence of Cl(-), I(-) or Br(-) but not gluconate. Therefore, functional NBF1 and Cl(-) transport are required for inhibition of ENaC in Xenopus oocytes, while the PDZ-BD is not essential.
Boucherot
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School of Biomedical Sciences, Department of Physiology and Pharmacology, University of Queensland, St. Lucia, 4072, Brisbane, Qld, Australia.
Schreiber
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Kunzelmann
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D000818:Animals; D001665:Binding Sites; D001965:Bromides / Q000737:chemistry; D002478:Cells, Cultured; D018118:Chloride Channels / Q000737:chemistry*; D002712:Chlorides / Q000737:chemistry; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000737:chemistry* / Q000235:genetics; D004563:Electrochemistry; D004848:Epithelium / Q000737:chemistry; D005786:Gene Expression Regulation; D007454:Iodides / Q000737:chemistry; D009154:Mutation; D009865:Oocytes; D026941:Sodium Channel Blockers; D015222:Sodium Channels / Q000737:chemistry* / Q000235:genetics; D014162:Transfection; D014981:Xenopus
D001965:Bromides; D018118:Chloride Channels; D002712:Chlorides; D007454:Iodides; D026941:Sodium Channel Blockers; D015222:Sodium Channels; D019005:Cystic Fibrosis Transmembrane Conductance Regulator