Excess of ovarian nerve growth factor impairs embryonic development and causes reproductive and metabolic dysfunction in adult female mice.

Nerve growth factor (NGF) is critical for the development and maintenance of the peripheral sympathetic neurons. NGF is also involved in the ovarian sympathetic innervation and in the development and maintenance of folliculogenesis. Women with the endocrine disorder, polycystic ovary syndrome (PCOS), have an increased sympathetic nerve activity and increased ovarian NGF levels. The role of ovarian NGF excess in the PCOS pathophysiology and in the PCOS-related features is unclear. Here, using transgenic mice overexpressesing NGF in the ovarian theca cells (17NF mice), we assessed the female embryonic development, and the reproductive and metabolic profile in adult females. Ovarian NGF excess caused growth restriction in the female fetuses, and a delayed gonocyte and primary oocyte maturation. In adulthood, the 17NF mice displayed irregular estrous cycles and altered ovarian expression of steroidogenic and epigenetic markers. They also exhibited an increased sympathetic output with increased circulating dopamine, and metabolic dysfunction reflected by aberrant adipose tissue morphology and function, impaired glucose metabolism, decreased energy expenditure, and hepatic steatosis. These findings indicate that ovarian NGF excess leads to adverse fetal development and to reproductive and metabolic complications in adulthood, mirroring common features of PCOS. This work provides evidence that NGF excess may be implicated in the PCOS pathophysiology.

Dissecting the Impact of Maternal Androgen Exposure on Developmental Programming through Targeting the Androgen Receptor.

Women with polycystic ovary syndrome (PCOS) exhibit sustained elevation in circulating androgens during pregnancy, an independent risk factor linked to pregnancy complications and adverse outcomes in offspring. Yet, further studies are required to understand the effects of elevated androgens on cell type-specific placental dysfunction and fetal development. Therefore, a PCOS-like mouse model induced by continuous androgen exposure is examined. The PCOS-mice exhibited impaired placental and embryonic development, resulting in mid-gestation lethality. Co-treatment with the androgen receptor blocker, flutamide, prevents these phenotypes including germ cell specification. Comprehensive profiling of the placenta by whole-genome bisulfite and RNA sequencing shows a reduced proportion of trophoblast precursors, possibly due to the downregulation of Cdx2 expression. Reduced expression of Gcm1, Synb, and Prl3b1 is associated with reduced syncytiotrophoblasts and sinusoidal trophoblast giant cells, impairs placental labyrinth formation. Importantly, human trophoblast organoids exposed to androgens exhibit analogous changes, showing impaired trophoblast differentiation as a key feature in PCOS-related pregnancy complications. These findings provide new insights into the potential cellular targets for future treatments.

Epiblast-like stem cells established by Wnt/ß-catenin signaling manifest distinct features of formative pluripotency and germline competence.

Different formative pluripotent stem cells harboring similar functional properties have been recently established to be lineage neutral and germline competent yet have distinct molecular identities. Here, we show that WNT/ß-catenin signaling activation sustains transient mouse epiblast-like cells as epiblast-like stem cells (EpiLSCs). EpiLSCs display metastable formative pluripotency with bivalent cellular energy metabolism and unique transcriptomic features and chromatin accessibility. We develop single-cell stage label transfer (scSTALT) to study the formative pluripotency continuum and reveal that EpiLSCs recapitulate a unique developmental period in vivo, filling the gap of the formative pluripotency continuum between other published formative stem cells. WNT/ß-catenin signaling activation counteracts differentiation effects of activin A and bFGF by preventing complete dissolution of naive pluripotency regulatory network. Moreover, EpiLSCs have direct competence toward germline specification, which is further matured by an FGF receptor inhibitor. Our EpiLSCs can serve as an in vitro model for mimicking and studying early post-implantation development and pluripotency transition.

In Vitro Differentiation of Murine Embryonic Stem Cells (ESCs) into Primordial Germ Cell-like Cells (PGCLCs).

The ability to generate primordial germ cell-like cells (PGCLCs) from murine embryonic stem cells (ESCs) has enabled in vitro investigation of the molecular mechanisms regulating this process without the use of a mouse model. Here we describe the procedures from the culture of ESCs to the detection of PGCLCs in the embryoid bodies (spheroids).

Prenatal androgen exposure and transgenerational susceptibility to polycystic ovary syndrome.

How obesity and elevated androgen levels in women with polycystic ovary syndrome (PCOS) affect their offspring is unclear. In a Swedish nationwide register-based cohort and a clinical case-control study from Chile, we found that daughters of mothers with PCOS were more likely to be diagnosed with PCOS. Furthermore, female mice (F0) with PCOS-like traits induced by late-gestation injection of dihydrotestosterone, with and without obesity, produced female F1-F3 offspring with PCOS-like reproductive and metabolic phenotypes. Sequencing of single metaphase II oocytes from F1-F3 offspring revealed common and unique altered gene expression across all generations. Notably, four genes were also differentially expressed in serum samples from daughters in the case-control study and unrelated women with PCOS. Our findings provide evidence of transgenerational effects in female offspring of mothers with PCOS and identify possible candidate genes for the prediction of a PCOS phenotype in future generations.

NANOS2 acts as an intrinsic regulator of gonocytes-to-spermatogonia transition in the murine testes.

In the male mouse embryos, the primordial germ cells colonize the developing testes at E11.5. These resident germ cells termed gonocytes are the predecessors of spermatogonial stem cells (SSCs) and differentiating spermatogonia. Both of which are essential for male fertility where the former maintains the continuity of spermatogenesis and the latter generates pioneering waves of spermatozoa. Therefore the timely initiation of gonocytes-to-spermatogonia transition (GST) is an important process during which the cell fates of gonocytes might be segregated. However, it is unknown whether gonocytes are composed of a heterogeneous mixture of germ cells with distinct differentiation potentials during GST. Here, we find that gonocytes exhibit heterogeneity in terms of the expression pattern of at least three early spermatogonial marker genes namely Nanos2, Stra8 and Gfra1. NANOS2 expression levels are negatively correlated with those of STRA8 and GFRA1 before GST, while positive correlation with GFRA1 is established after GST. We further find that overexpression of NANOS2 results in the repression of GFRA1 and PLZF in gonocytes, leading to a delay in GST. On the other hand, loss of NANOS2 results in the up-regulation of GFRA1 and PLZF, indicating a precocious entry of GST. Taken together, our data suggest that NANOS2 functions as an intrinsic timekeeper of GST in the mouse testes.

Gonocytes-to-spermatogonia transition initiates prior to birth in murine testes and it requires FGF signaling.

Spermatogenesis is a continuous and highly coordinated process of spermatozoa production. In mice, this process is believed to initiate shortly after birth with the emergence of nascent spermatogonia in the testes. However, because the nascent spermatogonia originated from the gonocytes are morphologically indistinguishable from their predecessors and there is no clear definition for the gonocytes-to-spermatogonia transition (GST), it remains unclear when and how spermatogenesis is initiated in the mouse testes. To address these questions, we characterized the emergence of nascent spermatogonia in ICR mice. We found that GST is initiated in a subset of gonocytes as early as E18.5. These nascent spermatogonia express markers typical of undifferentiated spermatogonia residing in testes of adult mice. In addition to markers expression, we identified FOXO1 nuclear-to-cytoplasmic translocation as a novel feature of GST distinguishing nascent spermatogonia from the gonocytes. Using those criteria, we demonstrated that GST requires FGF signaling. When FGF signaling was inhibited pharmacologically, gonocytes retained nuclear FOXO1 expression, did not express spermatogonial markers and failed to proliferate. We found that FGF signaling acts upstream of GDNF and RA signalings for the activation of the MEK/ERK and PI3K/Akt pathways in germ cells during GST. Taken together, we defined the precise timing of GST and revealed FGF signaling as a master regulator of GST in the perinatal mouse testes.