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This Article Full Text Full Text (PDF) All Versions of this Article: 292/5/L1085    most recent 00445.2005v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Bossard, F. Articles by Gauthier, C. Search for Related Content PubMed PubMed Citation Articles by Bossard, F. Articles by Gauthier, C.

NHE-RF1 protein rescues F508-CFTR function

¹Institut National de la Santé et de la Recherche Médicale Unité 533, l' Institut du Thorax, Faculté de Médecine, Nantes; ²Centre National de la Recherche Scientifique Unité Mixte de Recherches 6187, Institut de Physiologie et Biologie Cellulaires, Université de Poitiers, Poitiers; and ³Faculté des Sciences et Techniques, Université de Nantes, Nantes, France

Submitted 19 October 2005 ; accepted in final form 6 December 2006

In cystic fibrosis (CF), the F508-CFTR anterograde trafficking from the endoplasmic reticulum to the plasma membrane is inefficient. New strategies for increasing the delivery of F508-CFTR to the apical membranes are thus pathophysiologically relevant targets to study for CF treatment. Recent studies have demonstrated that PDZ-containing proteins play an essential role in determining polarized plasma membrane expression of ionic transporters. In the present study we have hypothesized that the PDZ-containing protein NHE-RF1, which binds to the carboxy terminus of CFTR, rescues F508-CFTR expression in the apical membrane of epithelial cells. The plasmids encoding F508-CFTR and NHE-RF1 were intranuclearly injected in A549 or Madin-Darby canine kidney (MDCK) cells, and F508-CFTR channel activity was functionally assayed using SPQ fluorescent probe. Cells injected with F508-CFTR alone presented a low chloride channel activity, whereas its coexpression with NHE-RF1 significantly increased both the basal and forskolin-activated chloride conductances. This last effect was lost with F508-CFTR deleted of its 13 last amino acids or by injection of a specific NHE-RF1 antisense oligonucleotide, but not by NHE-RF1 sense oligonucleotide. Immunocytochemical analysis performed in MDCK cells transiently transfected with F508-CFTR further revealed that NHE-RF1 specifically determined the apical plasma membrane expression of F508-CFTR but not that of a trafficking defective mutant potassium channel (KCNQ1). These data demonstrate that the modulation of the expression level of CFTR protein partners, like NHE-RF1, can rescue F508-CFTR activity.

cystic fibrosis; F508 cystic fibrosis transmembrane conductance regulator; Na⁺/H⁺ exchanger regulatory factor isoform 1; polarized expression; traffic