FIBROBLAST GROWTH-FACTOR STIMULATES THE GENE-EXPRESSION AND PRODUCTION OF TISSUE INHIBITOR OF METALLOPROTEINASE-1 IN BOVINE GRANULOSA-CELLS

The hormonal control of tissue inhibitor of metalloproteinase-1 (TIMP- 1) gene expression and production by growth factors, gonadotrophins, a nd serum factors in cultured bovine granulosa cells (BGC) were investi gated. Confluent cultures of BGC were exposed to various factors in a defined medium and levels of TIMP-1 in the conditioned medium were det ermined by enzyme immunoassay. Basic fibroblast growth factor (bFGF) a nd acidic fibroblast growth factor (aFGF) showed potent stimulation of cell proliferation and TIMP-1 production by BGC, while insulin stimul ated growth but not TIMP-1 production. Basic FGF stimulated TIMP-1 pro duction and BGC cell proliferation in a dose-dependent manner. A time course of TIMP-1 production showed substantially increased levels betw een 18 and 24 h in both control and bFGF-stimulated BGC cultures with bFGF-stimulated cultures having markedly higher TIMP-1 production at a ll time points. Consistent with the TIMP-1 production data, bFGF and a FGF increased the expression of TIMP-1 mRNA as determined by northern blot analysis, while insulin, inhibited TIMP-1 mRNA levels. These resu lts indicate that FGF-induced TIMP-1 production by BGC may support bov ine embryo development in vitro.