Simultaneous Gene Deletion of Gata4 and Gata6 Leads to Early Disruption of Follicular Development and Germ Cell Loss in the Murine Ovary1

Abstract

Granulosa cell formation and subsequent follicular assembly are important for ovarian development and function. Two members of the GATA family of transcription factors, GATA4 and GATA6, are expressed in ovarian somatic cells early in development, and their importance in adult ovarian function has been recently highlighted. In this study, we demonstrated that the embryonic loss of Gata4 and Gata6 expression within the ovary results in a strong down-regulation of genes involved in the ovarian developmental pathway (Fst and Irx3) as well as diminished expression of the pregranulosa and granulosa cell markers SPRR2 and FOXL2, respectively. Postnatal ovaries deficient in both Gata genes show impaired somatic cell proliferation and arrested follicular development at the primordial stage, where oocytes are either enclosed by one layer of squamous granulosa cells or remain in germ cell nests/clusters. Furthermore, germ cell nests and primordial follicles are predominantly localized to the central region of the Sf1Cre; Gata4(flox/flox) Gata6(flox/flox) ovaries, where the boundary between the medulla and cortex is almost nonexistent. Lastly, most of the oocytes are lost early in development in conditional double mutant ovaries, which confirms the importance of normally differentiated granulosa cells as supporting cells for oocyte survival. Thus, both GATA4 and GATA6 proteins are fundamental regulators of granulosa cell differentiation and proliferation, and consequently of proper follicular assembly during normal ovarian development and function.

Combined Loss of the GATA4 and GATA6 Transcription Factors in Male Mice Disrupts Testicular Development and Confers Adrenal-Like Function in the Testes

“…This is the most parsimonious explanation for the normal lifespan of the Sf1Cre; Gata4 flox/flox Gata6 flox/flox males, whereas their female littermates all die within 2 weeks after birth (17). Intriguingly, human patients with congenital adrenal hyperplasia develop testicular adrenal rest tumors that express the adrenal cortex-specific genes CYP11B1, CYP11B2, and MC2R (62).…”

“…However, it was only recently demonstrated that the fetal mouse testis harbors a limited number of cells that ; however, males survive and live normal lifespans, in contrast to their female littermates, which die shortly after birth (17). We hypothesized that steroidogenic gene expression in the testes of Sf1Cre; Gata4 flox/flox Gata6 flox/flox animals stems from the expansion of their adrenal-like population.…”

“…IF experiments were carried out as previously described (16,17). The primary antibodies and experimental conditions are listed in the supplemental antibody table.…”

FOXO1/3 and PTEN Depletion in Granulosa Cells Promotes Ovarian Granulosa Cell Tumor Development

“…Thus, FOXL2 appears to impact granulosa cell functions at distinct stages of follicle development (26 -28). GATA4 and GATA6 also impact granulosa cell fate specification (11,29), functions, proliferation and follicle formation, in part by regulating expression of FOXL2 and follistatin (29,30). Activins (homoand heterodimers of INHBA and INHBB) signal through the small mothers against decapentaplegic (SMAD) 2/3 pathway and when unopposed as in the Inha knockout (KO) mouse appear to impact GCT formation (31).…”

Involvement of FOXL2 and RSPO1 in Ovarian Determination, Development, and Maintenance in Mammals

“…Some factors have been already pointed out as being important for FOXL2/Foxl2 upregulation. Among them, GATA factors appear to be good candidates since it has been shown that Foxl2 expression is drastically decreased in Gata4 , Gata6, or Fog2 mutant mice [Manuylov et al, 2008;Padua et al, 2014]. However, this could also be the result of an indirect effect due to defective differentiation of XX supporting cells.…”