We demonstrated previously that mammalian sex determination requires both GATA4 and FOG2 transcription regulators and relies on their direct interaction to assemble the functioning testis. Our recent data reveals that in gonadal development GATA4-FOG2 transcription complex acts to control the extracellular signaling in both sexes. This application describes the experimental plan designed to characterize the impact of the WNT/DKK signaling on sex determination and development of the female reproductive system. We have identified the Dkk1 gene as a target of GATA4-FOG2 repression in the developing ovary. The expression of Dkk1 was dramatically increased (~10 fold) in embryonic gonads with GATA4-FOG2 interaction loss. We also identified other genes that are no longer expressed or strongly down-regulated in the GATA4 or FOG2 (GATA4/FOG2) XX mutants. Several of these genes (e.g., Wnt4, follistatin (Fst) and Foxl2) are known to be required for normal female development, while other genes (e.g., Sp5, Sprr2d, Irx3 and Gng13) have been recently identified as sexually dimorphic by us and others. We also show that the tissue-specific ablation of the ?-catenin gene in the gonads disrupts female development while testis development in the absence of ?-catenin proceeds as normal. Control of ovarian development as well as the canonical Wnt/??-catenin pathway by the GATA4-FOG2 transcriptional complex presents a novel insight into the crosstalk of transcriptional regulation and extracellular signaling in ovarian development. Now, using available to us 1) Gata4floxed , 2) Fog2floxed and 3) Gata4floxed/ki mice we will delete Gata4 and Fog2 genes during embryogenesis with Sf1Cre to generate fetuses and neonatal animals with Gata4 gene loss, Fog2 gene loss and GATA4-FOG2 interaction loss, respectively. To determine the function for canonical ?-catenin signaling in ovarian development we will analyze mice with gonadal loss of ?-catenin and mice with a loss of the Lrp6 receptor required for canonical ?-catenin signaling. Finally, we will examine sexual development in a) Dkk1 null embryos and b) compound mutant Fog2-/-Dkk1-/-, GATA4ki/ki/Dkk1-/- and Wt1-Sox9/Dkk-/- embryos;and using the tetO-Dkk1 mouse strain we will over-express Dkk1 specifically in embryonic gonads to separate this event from other consequences of the Gata4/Fog2 loss. Analysis of these mouse mutants should provide a novel insight into the fundamental aspects of gonadal differentiation, somatic-germ cell interaction and germ cell differentiation.
The goal of this project is to understand the early ovarian development in mice. This is relevant to human health as a genetic basis for the majority of human sex determination disorders remains poorly understood. Intersex and sex reversal syndromes often result in infertility and genital abnormalities together with long-term psychological trauma in affected sufferers. In addition, genes that function in the developing ovary are likely candidates for factors that affect the female germ line;when expressed abnormally, such genes can negatively affect the quality of eggs and the early embryos either in natural or in assisted reproduction.
|Padua, Maria B; Fox, Shawna C; Jiang, Tianyu et al. (2014) Simultaneous gene deletion of gata4 and gata6 leads to early disruption of follicular development and germ cell loss in the murine ovary. Biol Reprod 91:24|
|Tevosian, Sergei G (2014) Transgenic mouse models in the study of reproduction: insights into GATA protein function. Reproduction 148:R1-R14|
|Tevosian, S G (2013) Genetic control of ovarian development. Sex Dev 7:33-45|
|Tevosian, Sergei (2013) DMRT1 owner's manual: synchronized installation required to operate. Biol Reprod 88:50|
|Efimenko, Evgeni; Padua, Maria B; Manuylov, Nikolay L et al. (2013) The transcription factor GATA4 is required for follicular development and normal ovarian function. Dev Biol 381:144-58|
|Tevosian, Sergei G (2012) Gone without the WNT: a requirement for WNT5A in germ cell migration and testis development. Biol Reprod 86:1-2|
|Zaytouni, Tamara; Efimenko, Evgeni E; Tevosian, Sergei G (2011) GATA transcription factors in the developing reproductive system. Adv Genet 76:93-134|
|Manuylov, N L; Zhou, B; Ma, Q et al. (2011) Conditional ablation of Gata4 and Fog2 genes in mice reveals their distinct roles in mammalian sexual differentiation. Dev Biol 353:229-41|
|Manuylov, Nikolay L; Tevosian, Sergei G (2009) Cardiac expression of Tnnt1 requires the GATA4-FOG2 transcription complex. ScientificWorldJournal 9:575-87|
|Tevosian, Sergei G; Manuylov, Nikolay L (2008) To beta or not to beta: canonical beta-catenin signaling pathway and ovarian development. Dev Dyn 237:3672-80|
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