Retinoic acid-regulated cellular differentiation and mucin gene expression in isolated rabbit tracheal-epithelial cells in culture

Rabbit tracheal epithelial cells were cultured in a serum-free and hormone-supplemented medium with and without retinoic acid. The cells showed time-dependent mucin gene expression when cultured in the medium with retinoic acid. In the absence of retinoic acid, however, mucin mRNA was barely detectable in the cells. When retinoic acid was added back to the medium, the mucin message was prominent again. Actinomycin D and cycloheximide did not inhibit mucin gene expression. The mucin message was slightly elevated by cAMP agonists. A mucin antisense oligomer inhibited the retinoic acid-induced mucin mRNA expression and secretion, thus offering an alternate approach in the management of mucus hypersecretion in upper airway respiratory diseases such as chronic bronchitis, asthma, and cystic fibrosis.