Mucin secretion by the human colon cell line LS174T is regulated by bile salts

We recently reported that bile salts play a role in the regulation of mucinsecretion by cultured dog gallbladder epithelial cells. In this study wehave examined whether bile salts also influence mucin secretion by thehuman epithelial colon cell line LS174T. Solutions of bile salts wereapplied to monolayers of LS174T cells. Mucin secretion was quantified bymeasuring the secretion of [3H]GlcNAc labeled glycoproteins. Bothunconjugated bile salts as well as taurine conjugated bile salts stimulatedmucin secretion by the colon cells in a dose-dependent fashion. Hydrophobicbile salts were more potent stimulators than hydrophilic bile salts. Free(unconjugated) bile salts were more stimulatory compared with their taurineconjugated counterparts. Stimulation of mucin secretion by LS174T cells wasfound to occur at much lower bile salt concentrations than in theexperiments with the dog gallbladder epithelial cells. The protein kinase Cactivators PMA and PDB had no stimulatory effect on mucin secretion. Weconclude that mucin secretion by the human colon epithelial cell lineLS174T is regulated by bile salts. We suggest that regulation of mucinsecretion by bile salts might be a common mechanism, by which differentepithelia protect themselves against the detergent action of bile salts, towhich they are exposed throughout the gastrointestinal tract.