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

Production of activin was studied in four cell lines of epithelial cel ls: FRTL-5, JCT-12, GH(4)C(1), and FHs74Int cells. Bioactivity of acti vin was detected in conditioned media of FRTL-5, JCT-12 and FHs74Int c ells. 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 rele ase of bioactive activin in middle to late G(1) phase. In addition, ba sic FGF (bFGF), which had no effect on DNA synthesis in these cells, a lso increased release of activin. In bFGF-treated FHs74Int cells, bioa ctive activin was released within 4 hr of the addition of bFGF. The re verse-transcription polymerase chain reaction reveals that mRNA for on ly the beta(A) subunit of activin is expressed in these cells. Immunob lotting of lysate from serum-treated cells using anti-human activin A antibody indicated the existence of a 12.5-kDa protein under a reducin g condition. FHs74Int cells did not express binding site for [I-125]ac tivin A and exogenous activin A did not affect DNA synthesis in these cells. These results indicate that FHs74Int cells derived from human e mbryonic intestine synthesize and release activin A. Activin A release d from intestinal epithelial cells might be a modulatory factor in cel ls in intestinal mucosa.