Differential susceptibility of male and female germ cells to glucocorticoid-mediated signaling [RNAseq_DEX_Male]
While physiologic stress has long been known to impair mammalian reproductive capacity through hormonal dysregulation, mounting evidence now suggests that stress experienced prior to or during gestation may also negatively impact the health of future offspring. Rodent models of gestational physiologic stress can induce neurologic and behavioral phenotypes that persist for up to three generations, suggesting that stress signals can induce lasting epigenetic changes in the germline. Treatment with glucocorticoid stress hormones is sufficient to recapitulate the transgenerational phenotypes seen in physiologic stress models. These hormones are known to bind and activate the glucocorticoid receptor (GR), a ligand-inducible transcription factor, thus implicating GR-mediated signaling as a potential contributor to the transgenerational inheritance of stress-induced phenotypes. Here we demonstrate dynamic spatiotemporal regulation of GR expression in the mouse germline, showing expression in the fetal oocyte as well as the perinatal and adult spermatogonia. Functionally, we find that fetal oocytes are intrinsically buffered against changes in GR signaling, as neither genetic deletion of GR nor GR agonism with dexamethasone altered the transcriptional landscape or the progression of fetal oocytes through meiosis. In contrast, our studies revealed that the male germline is susceptible to glucocorticoid-mediated signaling, specifically by regulating RNA splicing within the spermatogonia, although this does not abrogate fertility. Together, our work suggests a sexually dimorphic function for GR in the germline, and represents an important step towards understanding the mechanisms by which stress can modulate the transmission of genetic information through the germline. Overall design: To investigate the role of glucocorticoid signaling in male germ cells, we performed RNA-seq on germ cells and somatic cells of the testis following administration of the glucocorticoid receptor agonist, dexamethasone (dex). Pregnant dams were dosed by IP with 10 µg dex / gram (or saline vehicle) at E17.5 and E18.5, and postnatal pups were dosed subcutaneously at PN0 with the same dose. Testes were harvested at PN1, and germs cells (OCT4-GFP positive) and somatic cells (OCT4-GFP negative) were FACS sorted prior to performing bulk RNA-seq.