PRODUCTION OF ACTIVIN-A IN HUMAN INTESTINAL EPITHELIAL-CELL LINE

Production of activin was studied in four cell lines of epithelial cells: FRTL-5, JCT-12, GH(4)C(1), and FHs74Int cells. Bioactivity of activin was detected in conditioned media of FRTL-5, JCT-12 and FHs74Int cells. Among these three cell lines, FHs74Int cells, which were derived from human embryonic intestine, released a relatively large amount of bioactive activin. In these cells, serum and epidermal growth factor (EGF), which were capable of stimulating DNA synthesis, augmented release of bioactive activin in middle to late G(1) phase. In addition, basic FGF (bFGF), which had no effect on DNA synthesis in these cells, also increased release of activin. In bFGF-treated FHs74Int cells, bioactive activin was released within 4 hr of the addition of bFGF. The reverse-transcription polymerase chain reaction reveals that mRNA for only the beta(A) subunit of activin is expressed in these cells. Immunoblotting of lysate from serum-treated cells using anti-human activin A antibody indicated the existence of a 12.5-kDa protein under a reducing condition. FHs74Int cells did not express binding site for [I-125]activin A and exogenous activin A did not affect DNA synthesis in these cells. These results indicate that FHs74Int cells derived from human embryonic intestine synthesize and release activin A. Activin A released from intestinal epithelial cells might be a modulatory factor in cells in intestinal mucosa.