Expression of messenger ribonucleic acid for the antiapoptosis gene p11 inthe rat ovary: Gonadotropin stimulation in granulosa cells of preovulatoryfollicles

P11, a member of the S100 family of calcium-binding proteins, has been show n to interact with BAD (Bcl-xL/Bcl-2-associated death promoter) in the yeas t two-hybrid protein-protein interaction assay. Because overexpression of P 11 dampens the proapoptotic activity of BAD in transfected cells, we tested the possibility that the expression of this antiapoptotic protein may be r egulated by gonadotropins and other survival factors in the ovary. Northern blot analysis of ovaries obtained from prepubertal rats revealed an increa sed expression of P11 messenger RNA (mRNA) during prepubertal development i n the theca cells of preantral and early antral follicles. Treatment of imm ature rats with PMSG did not affect P11 expression, whereas treatment of PM SG-primed rats with an ovulatory dose of human (h)CG stimulated ovarian P11 mRNA within 6-9 h in the granulosa cells of preovulatory follicles. Treatm ent of cultured preovulatory follicles in vitro with LH further confirmed t he time-dependent stimulation of P11 by gonadotropins. In addition, treatme nt of cultured preovulatory follicles with MDL-12,330A, an inhibitor of ade nylate cyclase, inhibited LH-stimulated P11 mRNA, whereas treatment with fo rskolin, an adenylate cyclase activator, but not the protein kinase C activ ator, 2-O-tetradecanol-phorbal-13-acetate, mimicked the LH action, suggesti ng the role of adenylate cyclase activation in P11 expression. Treatment wi th other follicle survival factors, including the epidermal growth factor, the basic fibroblast growth factor, and interleukin-1 beta, could also stim ulate P11 expression in cultured preovulatory follicles. These results demo nstrate the expression of P11 mRNA in theca cells of different-sized follic les and in granulosa cells of preovulatory follicles following gonadotropin stimulation, and suggest that P11 may mediate, at least partially, the sur vival action of gonadotropins during the ovulatory process.