Ovarian thecal cells produce transforming growth factor-β which can regulate granulosa cell growth

Abstract

Ovarian thecal cells in culture were found to synthesize and secrete transforming growth factor-β (TGFÎ2). A component in thecal cell-conditioned medium was immunologically similar to TGFβ, as assessed with a RIA, and inhibited specific binding of TGFÎ2 to its cell surface receptors. Thecal cell-secreted proteins also contained TGFÎ2 biological activity, which was determined by stimulation of soft agar colony formation by AKR-2B indicator cells. Specific TGFÎ2 antibodies precipitated a 25 K protein from radiolabeled thecal cell-secreted protein that comigrated with purified platelet-derived TGFÎ2. Both bovine thecal cell and rat thecal/interstitial cell preparations produced TGFÎ2, which required acid treatment to obtain fully active samples. The physiological significance of TGFÎ2 production by thecal cells was addressed through an analysis of the effects of TGFÎ2 on bovine granulosa cell growth. TGFÎ2 inhibited epidermal growth factor stimulation of granulosa cell growth, but alone it had no apparent influence. Observations indicate that ovarian thecal cells produce TGFÎ2, which can regulate granulosa cell growth and differentiation. Discussion of thecal cell-granulosa cell interactions and the possible functions of TGFÎ2 in the ovary is presented. © 1987 by The Endocrine Society.