Expression and Regulation of Transcription Factors GATA-4 and GATA-6 in Developing Mouse Testis¹

Abstract

Previous studies have shown that transcription factors GATA-4 and GATA-6 are expressed in granulosa and thecal cells of the mouse ovary and that GATA-4 expression in ovarian tissue is regulated by gonadotropins. Given the emerging role of GATA-4 and GATA-6 in gonadal cells, we have now studied the expression and regulation of these factors in the mouse testis and testicular cell lines. In situ hybridization demonstrated GATA-4 messenger RNA (mRNA) in the fetal testis at 13.5 days postcoitum. Both GATA-4 and GATA-6 transcripts were observed in late fetal, neonatal, juvenile, and adult Sertoli cells. In addition, GATA-4 mRNA was detected in interstitial cells throughout development. Immunohistochemistry demonstrated GATA-4 protein in both Sertoli and Leydig cells in postnatal animals. The regulation of GATA-4 and GATA-6 expression was explored using established testicular cell lines. Treatment of Leydig tumor cell lines with hCG resulted in a modest, but statistically significant, increase in the steady state level of GATA-4 mRNA, comparable to the previously described effect of FSH on GATA-4 expression in Sertoli cell lines. Gonadotropin or androgen action was not, however, a prerequisite for the basal expression of GATA-4 or GATA-6 in the testis, as their presence in Sertoli and Leydig cells was demonstrated in genetically hypogonadal hpg mice, in rats treated with GnRH receptor antagonist, and in Sertoli cells after chemical abolition of Leydig cells. Cotransfection studies using a GATA-4 expression plasmid and an inhibin alpha promoter/reporter gene construct in Leydig and granulosa tumor cell lines revealed that the inhibin alpha promoter harboring essential GATA-binding sites can be trans-activated by GATA-4. In light of these results, we propose that transcription factors GATA-4 and GATA-6 play differing roles in the maturation and function of testicular somatic cells.

Gata4 Regulates Testis Expression ofDmrt1

“…However, there are also earlier reports that contradict the above findings regarding temporal Gata4 expression in postnatal testis. As reported in these papers, Gata4 expression is particularly intense in Sertoli cells of neonatal testis until day 4 and appears somewhat weaker or is entirely lost in pubertal and adult testes (13,14,42). However, in evaluating some of the data on Gata4 and Dmrt1 expression in the postnatal testis, changes in Sertoli cell levels cannot be easily deduced (from Northern or Western blot analyses) because of the significant dilution effect from induction of nonexpressing germ cells.…”

In search of rat stem Leydig cells: Identification, isolation, and lineage-specific development

“…GATA4, a nuclear transcription factor that has been shown to be present in steroidogenic cell lineages (19,20), is expressed by the SLCs, but whether these cells are uni-or pluripotential will require further analysis.…”

GATA DNA-Binding Protein Expressed in Mouse I-10 Leydig Testicular Tumor Cells

“…Leydig cells express GATA-4 specifically throughout the later stages of fetal development, and in neonatal and adult animals (12). Since Leydig tumor cell line I-10 cells exclusively express GATA-4 in a significant amount, as demonstrated in this study, this cell line should be a model system for studies on Leydig cell functions such as steroid biosynthesis (13).…”

“…These discrepancies could be ascribed to the compensation by overexpressed GATA-6 (7,8). Recently, it was reported that testicular cells express GATA-4; Leydig cells only express GATA-4, while Sertoli cells express both GATA-4 and GATA-6 together with GATA-1 (11,12). To examine the roles of GATA proteins in testis, it is advantageous to use testisderived cultured cells which express GATA proteins.…”