Genistein restores functional interactions between Delta F508-CFTR and ENaC in Xenopus oocytes.
The cystic fibrosis transmembrane conductance regulator (CFTR), in addition to its Cl(-) channel properties, has regulatory interactions with other epithelial ion channels including the epithelial Na(+) channel (ENaC). Both the open probability and surface expression of wild type CFTR Cl(-) channels are increased significantly when CFTR is co-expressed in Xenopus oocytes with alphabetagamma-ENaC, and conversely, the activity of ENaC is inhibited following wild type CFTR activation. Using the Xenopus oocyte expression system, a lack of functional regulatory interactions between DeltaF508-CFTR and ENaC was observed following activation of DeltaF508-CFTR by forskolin and isobutylmethylxanthine (IBMX). Whole cell currents in oocytes expressing ENaC alone decreased in response to genistein but increased in response to a combination of forskolin and IBMX followed by genistein. In contrast, ENaC currents in oocytes co-expressing ENaC and DeltaF508-CFTR remained stable following stimulation with forskolin/IBMX/genistein. Furthermore, co-expression of DeltaF508-CFTR with ENaC enhanced the forskolin/IBMX/genistein-mediated activation of DeltaF508-CFTR. Our data suggest that genistein restores regulatory interactions between DeltaF508-CFTR and ENaC and that combinations of protein repair agents, such as 4-phenylbutyrate and genistein, may be necessary to restore DeltaF508-CFTR function in vivo.
Suaud
Laurence
L
Division of Pulmonary Medicine, Children's Hospital of Philadelphia, Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, 19104, USA.
Li
Jinqing
J
Jiang
Qinshi
Q
Rubenstein
Ronald C
RC
Kleyman
Thomas R
TR
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D005576:Colforsin / Q000494:pharmacology; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000378:metabolism*; D053503:Epithelial Sodium Channels; D005260:Female; D019833:Genistein / Q000494:pharmacology*; D006801:Humans; D009865:Oocytes / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D015222:Sodium Channels / Q000378:metabolism*; D014982:Xenopus laevis
C505032:CFTR protein, human; D053503:Epithelial Sodium Channels; D011994:Recombinant Proteins; D015222:Sodium Channels; C093349:cystic fibrosis transmembrane conductance regulator delta F508; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D005576:Colforsin; D000584:Amiloride; D019833:Genistein; D015056:1-Methyl-3-isobutylxanthine