Beta-oestradiol rescues DeltaF508CFTR functional expression in human cystic fibrosis airway CFBE41o- cells through the up-regulation of NHERF1.
BACKGROUND
CF (cystic fibrosis) is a disease caused by mutations within the CFTR (CF transmembrane conductance regulator) gene. The most common mutation, DeltaF508 (deletion of Phe-508), results in a protein that is defective in folding and trafficking to the cell surface but is functional if properly localized in the plasma membrane. We have recently demonstrated that overexpression of the PDZ protein NHERF1 (Na(+)/H(+)-exchanger regulatory factor 1) in CF airway cells induced both a redistribution of DeltaF508CFTR from the cytoplasm to the apical membrane and the PKA (protein kinase A)-dependent activation of DeltaF508CFTR-dependent chloride secretion. In view of the potential importance of the targeted up-regulation of NHERF1 in a therapeutic context, and since it has been demonstrated that oestrogen treatment increases endogenous NHERF1 expression, we tested the hypothesis that oestrogen treatment can increase NHERF1 expression in a human bronchiolar epithelial CF cell line, CFBE41o(-), with subsequent rescue of apical DeltaF508CFTR chloride transport activity.


RESULTS
We found that CFBE41o(-) cells do express ERs (oestrogen receptors) in the nuclear fraction and that beta-oestradiol treatment was able to significantly rescue DeltaF508CFTR-dependent chloride secretion in CFBE41o(-) cell monolayers with a peak between 6 and 12 h of treatment, demonstrating that the DeltaF508CFTR translocated to the apical membrane can function as a cAMP-responsive channel, with a significant increase in chloride secretion noted at 1 nM beta-oestradiol and a maximal effect observed at 10 nM. Importantly, knock-down of NHERF1 expression by transfection with siRNA (small interfering RNA) for NHERF1 inhibited the beta-oestradiol-dependent increase in DeltaF508CFTR protein expression levels and completely prevented the beta-oestradiol-dependent rescue of DeltaF508CFTR transport activity.


CONCLUSIONS
These results demonstrate that beta-oestradiol-dependent up-regulation of NHERF1 significantly increases DeltaF508CFTR functional expression in CFBE41o(-) cells.
Fanelli
Teresa
T
Department of General and Environmental Physiology, University of Bari, Via Amendola 165/A, Bari 70126, Italy.
Cardone
Rosa Angela
RA
Favia
Maria
M
Guerra
Lorenzo
L
Zaccolo
Manuela
M
Monterisi
Stefania
S
De Santis
Teresa
T
Riccardi
Stefania Maria
SM
Reshkin
Stephan Joel
SJ
Casavola
Valeria
V
D001692:Biological Transport; D002478:Cells, Cultured; D002712:Chlorides / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D003550:Cystic Fibrosis / Q000235:genetics / Q000378:metabolism*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects*; D006801:Humans; D009154:Mutation; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D020545:Respiratory Mucosa / Q000187:drug effects* / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
C505032:CFTR protein, human; D002712:Chlorides; D010750:Phosphoproteins; D034741:RNA, Small Interfering; D017923:Sodium-Hydrogen Exchangers; C093376:sodium-hydrogen exchanger regulatory factor; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D004958:Estradiol; D017868:Cyclic AMP-Dependent Protein Kinases