EXPRESSION AND HORMONAL-REGULATION OF TRANSCRIPTION FACTORS GATA-4 AND GATA-6 IN THE MOUSE OVARY

Two members of the GATA-binding family of transcription factors, GATA- 4 and GATA-6, are expressed in the vertebrate ovary. To gain insight i nto the role of these factors in ovarian cell differentiation and func tion, we used in situ hybridization to determine the patterns of expre ssion of GATA-4 and GATA-6 in mouse ovary during development and in re sponse to hormonal stimulation. GATA-4 messenger RNA(mRNA) was first e vident in the ovary around the time of birth. In the adult ovary, abun dant GATA-4 mRNA was detected in granulosa cells of primary and antral follicles, with lesser amounts of GATA-4 message detected in theca ce lls, germinal epithelium, and interstitial cells. Little or no GATA-4 mRNA was found in corpus luteum. GATA-6 message exhibited a different distribution in the ovary, with abundant expression evident in both gr anulosa cells and corpora lutea. Stimulation of 3-week-old females wit h PMSG or estrogen enhanced follicular expression of GATA-4 and GATA-6 transcripts. Subsequent induction of ovulation with human CG resulted in a decrease in GATA-4 mRNA expression in granulosa cells, whereas G ATA-6 mRNA expression persisted in granulosa cells after ovulation and in corpora lutea. Moreover, follicular apoptosis was associated with a decrease in the expression of GATA-4 but not GATA-6 message. Stimula tion of cultured gonadal cell lines with FSH resulted in increased exp ression of GATA-4 message, whereas GATA-6 mRNA expression was not affe cted. In light of these findings, the established role of other GATA-b inding proteins in hematopoetic cell differentiation and apoptosis, an d the presence of conserved GATA motifs in the promoters of genes expr essed selectively in ovary, we propose that GATA-4 and GATA-6 play dis tinct roles in follicular development and luteinization.