Association of lipids with mucins may take place prior to secretion: Studies with primary hamster tracheal epithelial cells in culture

Abstract

Confluent cultures of hamster tracheal surface epithelial (HTSE) cells are highly enriched with secretory cells and secrete mucins. Ultrastructural studies of cellular localization of these mucins show that mucins are found not only inside secretory granules but also on the apical surface of secretory cells during active secretion, and secreted mucins are highly associated with lipids. In the present communication, we analyzed lipids associated with both cellular and secreted mucins following metabolic radiolabeling of these cultured cells with [³H]palmitic acid. We found that profiles of lipids associated with both cellular and secreted mucins are almost identical not only qualitatively but also quantitatively. It is concluded that the lipid association with mucins seems to take place before secretion. The origin of the cell surface-bound mucins is discussed.