Transgenic mouse analysis of Sry expression during the pre‐ and peri‐implantation stage

Abstract

Background: The SRY/Sry gene is expressed in pre-Sertoli cells of the male genital ridge and functions as the mammalian testis determining factor (TDF). In addition, expression of SRY/Sry outside the genital ridge has been reported, including preimplantation embryos, although the functional significance of this is not well understood. Results: Using Cre-mediated lineage studies and transgenic reporter mouse models, we now show that promoter sequences of human, pig and mouse SRY drive robust reporter gene expression in epiblast cells of peri-implantation embryos between embryonic day (E) 4.5 and E6.5. Analysis of endogenous Sry expression revealed that linear transcripts are produced by means of multiple polyadenylation sites in E4.5 embryos. Within the epiblast, SRY reporter expression mimics the expression seen using a Gata4 reporter model, but is dissimilar to that seen using an Oct4 reporter model. In addition, we report that overexpression of mouse Sry in embryonic stem cells leads to down-regulation of the core pluripotency markers Sox2 and Nanog. Conclusion: We propose that SRY/Sry may function as a male-specific maturation factor in the peri-implantation mammalian embryo, providing a genetic mechanism to help explain the observation that male embryos are developmentally more advanced compared with female embryos, and suggesting a role for SRY beyond that of TDF. Developmental Dynamics 241:1192-1204, 2012. V C 2012 Wiley Periodicals, Inc.Key words: SRY; promoter; blastocyst; epiblast; male-specific maturation factor; pluripotency; Sox2; Oct4; Nanog Key findings:The proximal promoter of SRY/Sry from several mammalian species (pig, human and mouse) directs reporter gene expression in the epiblast of pre-and peri-implantation mouse embryos. Expression levels of SRY/Sry reporters coincide with the maturation stage of pre-and peri-implantation embryos, being positively correlated with a Gata4 reporter and negatively correlated with an Oct4 reporter. Overexpression of Sry in murine embryonic stem cells results in reduced expression of the pluripotency markers Sox2 and Nanog.

Male-biased aganglionic megacolon in the TashT mouse model of Hirschsprung disease involves upregulation of p53 protein activity and Ddx3y gene expression

“…Neuro2a neuroblastoma cells, F9 embryocarcinoma cells, P19 embryocarcinoma cells, and R1 embryonic stem cells were maintained and propagated as previously described [89,90]. To evaluate the activity of Myc Ddx3y-IRES-eGFP and Myc Sry-IRES-eGFP transgenic constructs, 3x10 5 Neuro2a cells were seeded in 6-well plates containing coverslips and transfected with Genejuice reagents (Novagen) in accordance with manufacturer's instructions.…”

Cell‐autonomous sex determination outside of the gonad

“…As such, it belongs within the framework of a general theory of sex determination, not outside of such a theory. Other sex differences are found prior to sexual differentiation of the gonads, indicating that the sex chromosomes encode factors that act within and outside of the gonads (O et al, 1988; Burgoyne et al, ; Bermejo‐Alvarez et al, ; Silversides et al, ; Nef et al, ; Dewing et al, ). As is discussed below, even after the gonads differentiate, the number of X chromosomes influences sex differences in the phenotype of cells and individuals, independent of the gonadal sex of the individual.…”

Sexually antagonistic epigenetic marks that canalize sexually dimorphic development

“…() in humans, and Silversides et al . () in mice, demonstrate that SRY is expressed in preimplantation embryos as well as later stage foetuses (prior to androgen signalling). Data from Banovich et al .…”