Overexpression of R domain eliminates cAMP-stimulated Cl- secretion in 9/HTEo- cells in culture.
The intracellular hydrophilic region of the cystic fibrosis transmembrane conductance regulator (CFTR), the R domain, has been postulated to be a regulator of the Cl-channel. Under basal conditions R blocks the channel, but when phosphorylated, R undergoes conformational change to open the channel. Overexpression of R in 9/HTEo- cells, a human tracheal epithelial cell line with adenosine 3',5' -cyclic monophosphate (cAMP)-regulated Cl- conductance due to CFTR, caused reduced basal Cl- conductance and elimination of its response to isoproterenol, but ionomycin-stimulated Cl- efflux was preserved. Cells which overexpressed R showed no downregulation of endogenous CFTR mRNA and had normal cAMP production and protein kinase A (PKA) activity, so R did not act at these levels. Although the precise mechanism by which R affects CFTR conductance is undetermined, these cell lines could be useful in separating the cell biological consequences of impaired Cl- transport from those of mutant CFTR per se.
Perez
A
A
Department of Pediatrics, Case Western Reserve University, Rainbow Babies and Childrens Hospital, Cleveland, Ohio 44106, USA.
Risma
K A
KA
Eckman
E A
EA
Davis
P B
PB
D001483:Base Sequence; D002118:Calcium / Q000502:physiology; D002460:Cell Line; D002712:Chlorides / Q000378:metabolism* / Q000502:physiology; D000242:Cyclic AMP / Q000096:biosynthesis / Q000494:pharmacology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics* / Q000378:metabolism; D004553:Electric Conductivity; D005456:Fluorescent Dyes; D015870:Gene Expression; D006801:Humans; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes / Q000235:genetics; D011806:Quinolinium Compounds / Q000378:metabolism; D014132:Trachea / Q000166:cytology / Q000502:physiology*
C505032:CFTR protein, human; D002712:Chlorides; D005456:Fluorescent Dyes; D015345:Oligonucleotide Probes; D011806:Quinolinium Compounds; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; C052335:6-methoxy-N-(3-sulfopropyl)quinolinium; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D002118:Calcium