Rescue of DeltaF508-CFTR (cystic fibrosis transmembrane conductance regulator) by curcumin: involvement of the keratin 18 network.
The most common mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, DeltaF508, causes retention of DeltaF508-CFTR in the endoplasmic reticulum and leads to the absence of CFTR Cl(-) channels in the plasma membrane. DeltaF508-CFTR retains some Cl(-) channel activity so increased expression of DeltaF508-CFTR in the plasma membrane can restore Cl(-) secretion deficiency. Recently, curcumin was shown to rescue DeltaF508-CFTR localization and function. In our previous work, the keratin 18 (K18) network was implicated in DeltaF508-CFTR trafficking. Here, we hypothesized that curcumin could restore a functional DeltaF508-CFTR to the plasma membrane acting via the K18 network. First, we analyzed the effects of curcumin on the localization of DeltaF508-CFTR in different cell lines (HeLa cells stably transfected with wild-type CFTR or DeltaF508-CFTR, CALU-3 cells, or cystic fibrosis pancreatic epithelial cells CFPAC-1) and found that it was significantly delocalized toward the plasma membrane in DeltaF508-CFTR-expressing cells. We also performed a functional assay for the CFTR chloride channel in CFPAC-1 cells treated or not with curcumin and detected an increase in a cAMP-dependent chloride efflux in treated DeltaF508-CFTR-expressing cells. The K18 network then was analyzed by immunocytochemistry and immunoblot exclusively in curcumin-treated or untreated CFPAC-1 cells because of their endogenic DeltaF508-CFTR expression. After curcumin treatment, we observed a remodeling of the K18 network and a significant increase in K18 Ser52 phosphorylation, a site directly implicated in the reorganization of intermediate filaments. With these results, we propose that K18 as a new therapeutic target and curcumin, and/or its analogs, might be considered as potential therapeutic agents for cystic fibrosis.
Lipecka
Joanna
J
Institut National de la Sante et de la Recherche Medicale U467, Université René Descartes Paris 5, Faculté de Médecine Paris 5, Paris, France.
Norez
Caroline
C
Bensalem
Noura
N
Baudouin-Legros
Maryvonne
M
Planelles
Gabrielle
G
Becq
Frédéric
F
Edelman
Aleksander
A
Davezac
Noélie
N
D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism; D003474:Curcumin / Q000494:pharmacology*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D015151:Immunoblotting; D053538:Keratin-18; D007633:Keratins / Q000378:metabolism*; D009154:Mutation; D013997:Time Factors
C488421:KRT18 protein, human; D053538:Keratin-18; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D007633:Keratins; D003474:Curcumin