Expression of specific protein kinase C (PKC) isoforms and ligand-specific activation of PKCalpha in late gestation fetal lung.

Epidermal growth factor receptor signaling plays an important role in lung maturation. The authors hypothesized that specific protein kinase C (PKC) isoforms are expressed and activated by epidermal growth factor (EGF) and transforming growth factor alpha (TGFalpha) (EGF receptor [EGFR] ligands) in fetal lung fibroblasts. The authors found 4 PKC isoforms expressed in gestational day 19 (d19) fetal rat lung fibroblasts, and focused on PKCalpha because of its developmental expression pattern. PKCalpha immunolocalization in d17, d19, and d21 fetal lung fibroblasts was similar to EGFR. PKCalpha expression decreased with lung maturation. EGF, but not TGFalpha, stimulated PKCalpha activation and membrane translocation. Further studies of PKCalpha functions in fetal lung development are clearly needed.