Bronchial epithelial cell migration is required for the repair of damaged airway epithelium. We hypothesized that bronchial epithelial cell migration during wound repair is influenced by cAMP and the activity of its cyclic nucleotide-dependent protein kinase, protein kinase A (PKA). We found that, when confluent monolayers of bronchial epithelial cells are wounded, an increase in PKA activity occurs. Augmentation of PKA activity with a cell-permeable analog of cAMP, dibutyryl adenosine 3',5'-cyclic monophosphate, isoproterenol, or a phosphodiesterase inhibitor accelerated migration of normal bronchial epithelial cells in in vitro wound closure assays and Boyden chamber migration assays. A role for PKA activity was also confirmed with a PKA inhibitor, KT-5720, which reduced stimulated migration. Augmentation of PKA activity reduced the levels of active Rho and the formation of focal adhesions. These studies suggest that PKA activation modulates Rho activity, migration mechanisms, and thus bronchial epithelial repair mechanisms.

Bronchial epithelial cell migration, attachment, and proliferation are important processes in response to airway injury. We have shown that tumor necrosis factor (TNF)-α stimulates the migration of bovine bronchial epithelial cells (BBEC) in vitro. We hypothesized that protein kinase C (PKC) may be one of the intracellular signaling mediators of TNF-α in BBEC. In this study, we have identified multiple PKC isoforms in BBEC and measured total cellular PKC activity. Polyclonal antibodies to the PKC-α, -β2, -δ, and -ε isoforms recognized protein bands around 80–90 kDa. BBEC primary cultures treated with either 500 U/ml TNF-α for 2–4 h or 100 ng/ml 12- O-tetradecanoylphorbol 13-acetate for 15 min resulted in three- to fivefold increases in PKC activity in the particulate fractions of crude cell lysates. This activity was inhibited by 1 μM calphostin C or 10 μM H-7. Similarly, TNF-α-stimulated BBEC migration was reduced at least twofold in the presence of H-7 or calphostin C. These studies suggest that the activation of PKC is necessary for TNF-α-stimulated BBEC migration.