Submitted on April 18, 2008
Revised on June 9, 2008
Accepted on June 26, 2008
EGF mediates calcium-activated chloride channel activation in the human bronchial epithelial cell line 16HBE14o-: involvement of the tyrosine kinase p60c-src
Claudette Jeulin1*, Virginie Seltzer2, Danielle Bailbe2, Karine Andreau2, and Francelyne Marano2
1 Universite Paris 7 Diderot
2 Universite Paris Diderot
* To whom correspondence should be addressed. E-mail: claudette.jeulin{at}univ-paris-diderot.fr.
Particulate atmospheric pollutants interact with the human airway epithelium which release cytokines, chemokines and EGFR ligands leading to pro-inflammatory responses. There is little information concerning the short-term effects of EGFR activation by extra-cellular ligands on ionic regulation of airway surface lining fluids. We identified in the membrane of human epithelial bronchial cells (16HBE14o-line) an endogenous calcium-voltage-dependent, outwardly rectifying small conductance chloride channel (CACC) and we examined the effects of EGF on CACC activity. Ion channel currents were recorded with the patch-clamp technique. In cell-attached membrane patches, CACC were activated by exposure of the external surface of the cells to physiological concentrations of EGF without any change in [Ca2+]i and inhibited by Tyrphostin AG1478 (an inhibitor of EGFR which also blocks EGF-dependent Src-family kinase activation). EGF activation of c-Src protein in 16HBE14o- cells was observed and signalling pathway elicited by EGFR was blocked by Tyrphostin AG1478. In excised inside-out membrane patches CACC were activated by exposure of the cytoplasmic face of the channels to the human recombinant Src(p60c-src)kinase with endogenous or exogenous ATP and inhibited by Lambda-phosphatase. Secretion of EGFR ligands by epithelial airway cells exposed to pollutants would then elicit a rapid and direct ionic response of CACC mediated by EGFR activation via Src kinase family-dependent signalling pathway.
