Protein phosphorylation responses in normal and cystic fibrosis airway epithelial cell lines

Monolayers of SV-40 immortalized human airway epithelial cell lines were stimulated with bradykinin and isoproterenol to study protein phosphorylation responses that accompany ion transport regulation in normal (BEAS) and cystic fibrosis (CF/T43) cells. Phosphorylation responses were analyzed by two-dimensional gel electrophoresis of postmicrosomal supernatant fractions of 32Pi-labeled cells. Isoproterenol increased the labeling of three phosphoproteins of M(r) 17,000, 18,000, and 37,000 that were equivalent to proteins known to undergo cAMP-dependent phosphorylation in T84 cell monolayers. Distinct proteins showed increased phosphorylation with bradykinin, including acidic proteins of M(r) 15,000 and 29,000. These resembled proteins exhibiting Ca(2+)-dependent phosphorylation T84 cells. The CF/T43 and BEAS cell protein phosphorylation responses were indistinguishable. These findings support the concept that the regulation and function of protein kinase A is normal in cystic fibrosis airway epithelia and that the abnormal cAMP-mediated regulation of chloride permeability in these cells is due to altered regulatory or effector proteins.