INVOLVEMENT OF PROTEIN-KINASE-C IN MUCUS SECRETION BY HAMSTER TRACHEAL EPITHELIAL-CELLS IN CULTURE

Abnormal regulation of airway mucus secretion may underlie many pulmonary diseases. The exact evidence for the involvement of intracellular signaling mechanisms in mucus secretion has not been fully elucidated to date. The purpose of this study is to clarify the involvement of protein kinase C in the secretion of high-molecular-weight glycoconjugates (HMWG) by hamster tracheal epithelial cells in culture, which elute in the void volume on Sepharose CL-4B column chromatography. HMWG were secreted by the cells cultured on the thick collagen gel, but not on the plastic plate. Two known activators of protein kinase C, 4 beta-phorbol 12 alpha-myristate 13-acetate (PMA) and 1-oleoyl-2-acetyl-sn-glycerol (OAG), stimulated HMWG secretion. In contrast, 4 alpha-phorbol 12,13-didecanoate, a biologically inactive phorbol, did not influence HMWG secretion. D-Sphingosine, an inhibitor of protein kinase C, suppressed the maximal PMA- (10(-8) M) and OAG- (200 mu M) stimulated HMWG secretion. PMA induced protein kinase C translocation from cytosol to membrane. These data indicate that protein kinase C is involved in HMWG secretion in hamster tracheal epithelial cells in culture.