Inhibition of protein kinase CK2 closes the CFTR Cl channel, but has no effect on the cystic fibrosis mutant deltaF508-CFTR.
BACKGROUND
Deletion of phenylalanine-508 (DeltaF508) from the first nucleotide-binding domain (NBD1) in the wild-type cystic fibrosis (CF) transmembrane-conductance regulator (wtCFTR) causes CF. However, the mechanistic relationship between DeltaF508-CFTR and the diversity of CF disease is unexplained. The surface location of F508 on NBD1 creates the potential for protein-protein interactions and nearby, lies a consensus sequence (SYDE) reported to control the pleiotropic protein kinase CK2.


METHODS
Electrophysiology, immunofluorescence and biochemistry applied to CFTR-expressing cells, Xenopus oocytes, pancreatic ducts and patient biopsies.


RESULTS
Irrespective of PKA activation, CK2 inhibition (ducts, oocytes, cells) attenuates CFTR-dependent Cl(-) transport, closing wtCFTR in cell-attached membrane patches. CK2 and wtCFTR co-precipitate and CK2 co-localized with wtCFTR (but not DeltaF508-CFTR) in apical membranes of human airway biopsies. Comparing wild-type and DeltaF508CFTR expressing oocytes, only DeltaF508-CFTR Cl(-) currents were insensitive to two CK2 inhibitors. Furthermore, wtCFTR was inhibited by injecting a peptide mimicking the F508 region, whereas the DeltaF508-equivalent peptide had no effect.


CONCLUSIONS
CK2 controls wtCFTR, but not DeltaF508-CFTR. Others find that peptides from the F508 region of NBD1 allosterically control CK2, acting through F508. Hence, disruption of CK2-CFTR interaction by DeltaF508-CFTR might disrupt multiple, membrane-associated, CK2-dependent pathways, creating a new molecular disease paradigm for deleted F508 in CFTR.
Treharne
Kate J
KJ
Centre for Cardiovascular and Lung Biology, University of Dundee, Ninewells Hospital, UK.
Xu
Zhe
Z
Chen
Jeng-Haur
JH
Best
O Giles
OG
Cassidy
Diane M
DM
Gruenert
Dieter C
DC
Hegyi
Péter
P
Gray
Michael A
MA
Sheppard
David N
DN
Kunzelmann
Karl
K
Mehta
Anil
A
D000494:Allosteric Regulation; D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport; D047390:Casein Kinase II / Q000032:analysis / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002460:Cell Line; D018118:Chloride Channels / Q000378:metabolism*; D006224:Cricetinae; D000242:Cyclic AMP / Q000378:metabolism; D003550:Cystic Fibrosis / Q000235:genetics; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D055724:Electrophysiological Phenomena; D006168:Guinea Pigs; D006801:Humans; D047468:Immunoprecipitation; D008969:Molecular Sequence Data; D009154:Mutation; D009865:Oocytes / Q000378:metabolism; D054730:Protein Interaction Domains and Motifs; D014981:Xenopus
D018118:Chloride Channels; C093349:cystic fibrosis transmembrane conductance regulator delta F508; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D000242:Cyclic AMP; D047390:Casein Kinase II