Mapping the follicle-specific regulation of extracellular vesicle-mediated microRNA transport in the southern white rhinoceros (Ceratotherium simum simum)†

Efforts to implement effective assisted reproductive technologies (ARTs) for the conservation of the northern white rhinoceros (NWR; Ceratotherium simum cottoni) to prevent its forthcoming extinction, could be supported by research conducted on the closely related southern white rhinoceros (SWR; Ceratotherium simum simum). Within the follicle, extracellular vesicles (EVs) play a fundamental role in the bidirectional communication facilitating the crucial transport of regulatory molecules such as microRNAs (miRNAs) that control follicular growth and oocyte development. This study aimed to elucidate the dynamics of EV-miRNAs in stage-dependent follicular fluid (FF) during SWR ovarian antral follicle development. Three distinct follicular stages were identified based on diameter: Growing (G; 11-17 mm), Dominant (D; 18-29 mm), and Pre-ovulatory (P; 30-34 mm). Isolated EVs from the aspirated FF of segmented follicle stages were used to identify EV-miRNAs previously known via subsequent annotation to all equine (Equus caballus; eca), bovine (Bos taurus; bta), and human (Homo sapiens; hsa) miRNAs. A total of 417 miRNAs were detected, with 231 being mutually expressed across all three stages, including eca-miR-148a and bta-miR-451 as the top highly expressed miRNAs. Distinct expression dynamics in miRNA abundance were observed across the three follicular stages, including 31 differentially expressed miRNAs that target various pathways related to follicular growth and development, with 13 miRNAs commonly appearing amidst two different comparisons. In conclusion, this pioneering study provides a comprehensive understanding of the stage-specific expression dynamics of FF EV-miRNAs in the SWR. These findings provide insights that may lead to novel approaches in enhancing ARTs to catalyze rhinoceros conservation efforts.

Follicular Atresia in Buffalo: Cocaine- and Amphetamine-Regulated Transcript (CART) and the Underlying Mechanisms

Atresia is a process in ovarian follicles that is regulated by hormone-induced apoptosis. During atresia, granulosa cell (GC) apoptosis is a key mechanism orchestrated through diverse signaling pathways. Cocaine- and amphetamine-regulated transcript (CART) signaling within ovarian GCs has been demonstrated to play a key role in the regulation of follicular atresia in cattle, pigs, and sheep. The present work aimed to investigate the potential local regulatory role of CART in GC apoptosis-induced follicular atresia in buffalo, focusing on the modulation of the AKT/GSK3β/β-catenin signaling pathways, which are the intracellular signaling pathways involved in cell viability. Our findings revealed increased expression of CARTPT and BAX and decreased levels of AKT, β-catenin, and CYP19A1 genes in atretic follicles compared to healthy follicles. Subsequently, CART treatment in the presence of FSH inhibited the FSH-induced increase in GC viability by reducing estradiol production and increasing apoptosis. This change was accompanied by an increase in the gene expression levels of both CARTPT and BAX. At the protein level, treatment with CART in the presence of FSH negatively affected the activity of AKT, β-catenin, and LEF1, while the activity of GSK3β was enhanced. In conclusion, our study shows how CART negatively influences buffalo GC viability, underlying the modulation of the AKT/GSK3β/β-catenin pathway and promoting apoptosis-a key factor in follicular atresia.

Diaph1 knockout inhibits mouse primordial germ cell proliferation and affects gonadal development

BACKGROUND

Exploring the molecular mechanisms of primordial germ cell (PGC) migration and the involvement of gonadal somatic cells in gonad development is valuable for comprehending the origins and potential treatments of reproductive-related diseases.

METHODS

Diaphanous related formin 1 (Diaph1, also known as mDia1) was screened by analyzing publicly available datasets (ATAC-seq, DNase-seq, and RNA-seq). Subsequently, the CRISPR-Cas9 technology was used to construct Diaph1 knockout mice to investigate the role of Diaph1 in gonad development.

RESULTS

Based on data from public databases, a differentially expressed gene Diaph1, was identified in the migration of mouse PGC. Additionally, the number of PGCs was significantly reduced in Diaph1 knockout mice compared to wild type mice, and the expression levels of genes related to proliferation (Dicer1, Mcm9), adhesion (E-cadherin, Cdh1), and migration (Cxcr4, Hmgcr, Dazl) were significantly decreased. Diaph1 knockout also inhibited Leydig cell proliferation and induced apoptosis in the testis, as well as granulosa cell apoptosis in the ovary. Moreover, the sperm count in the epididymal region and the count of ovarian follicles were significantly reduced in Diaph1 knockout mice, resulting in decreased fertility, concomitant with lowered levels of serum testosterone and estradiol. Further research found that in Diaph1 knockout mice, the key enzymes involved in testosterone synthesis (CYP11A1, 3β-HSD) were decreased in Leydig cells, and the estradiol-associated factor (FSH receptor, AMH) in granulosa cells were also downregulated.

CONCLUSIONS

Overall, our findings indicate that the knockout of Diaph1 can disrupt the expression of factors that regulate sex hormone production, leading to impaired secretion of sex hormones, ultimately resulting in damage to reproductive function. These results provide a new perspective on the molecular mechanisms underlying PGC migration and gonadal development, and offer valuable insights for further research on the causes, diagnosis, and treatment of related diseases.

The Role of Oxytocin in Polycystic Ovary Syndrome: A Systematic Review

Polycystic Ovary Syndrome (PCOS) is the most common endocrine disorder that affects women of reproductive age, representing the primary cause of anovulatory infertility. The nonapeptide oxytocin (OT) plays an important role in cognitive, emotional, and reproductive functions in human beings. Oxytocin receptors are expressed in several body parts, including the ovaries. Despite this, the possible role played by oxytocin in symptoms of PCOS is not clear. The present systematic review aimed at understanding the presence of possible oxytocin level alterations in PCOS, the connection between alterations of OT levels and the symptoms of PCOS, and the effect of oxytocin administration in PCOS. After a systematic search in the principal databases, eight studies, five human and three animal, were included. Four human studies and one animal study highlighted the role played by oxytocin in fertility issues related to PCOS. Three human and two animal studies investigated the role of body weight and OT levels. Studies that analyzed oxytocin basal levels in women agreed that PCOS is associated with a reduction in the serum level of oxytocin. Two human studies and one animal study agreed about lower levels of oxytocin, confirming a possible implication of the dysfunction of OT in the pathogenesis of PCOS.

Ontogeny of adropin and its receptor expression during postnatal development and its pro-gonadal role in the ovary of pre-pubertal mouse

Adropin, a highly conserved multifunctional peptide hormone, has a beneficial effect on the maintenance of gluco-lipid homeostasis, endothelial and cardiovascular functions. However, the expression and potential role of adropin in ovarian function are not fully elucidated. The present study aimed to investigate the expression of adropin and GPR19 in the mice ovary during various stages of postnatal development. This study also explored whether the treatment of adropin can modulate the timing of puberty, for which pre-pubertal mice were treated with adropin. The result showed the intense immunoreactivity of adropin in TICs, while GPR19 immunoreactivity was noted in GCs in infantile, pre-pubertal, and pubertal mice ovary. Also, adropin and GPR19 are highly expressed in the CL of the ovary of reproductively active mice. The fact that adropin expression in the ovary at different stages of postnatal development positively correlated with circulating progesterone and estradiol indicated that it has a role in the production of steroid hormones. Furthermore, the results of in vivo studies in pre-pubertal mice showed that adropin promotes early folliculogenesis by enhancing the proliferation (PCNA) of GCs of cortical ovarian follicles and promotes estradiol production by enhancing the expression of GPR19, StAR, CYP11A1 and aromatase proteins. Also, adropin treatment increases the Bax/Bcl2 ratio and expression of cleaved caspase-3 and ERα proteins, which may result in increased apoptosis of medullary follicles leading to the formation of a well-developed interstitium with interstitial glandular cells. Collectively, these findings indicate that adropin may be a factor that accelerates pubertal development in the ovary and could be utilized as a therapeutic approach for treating pubertal delay.

Estradiol Signaling at the Heart of Folliculogenesis: Its Potential Deregulation in Human Ovarian Pathologies

Estradiol (E2) is a major hormone controlling women fertility, in particular folliculogenesis. This steroid, which is locally produced by granulosa cells (GC) within ovarian follicles, controls the development and selection of dominant preovulatory follicles. E2 effects rely on a complex set of nuclear and extra-nuclear signal transduction pathways principally triggered by its nuclear receptors, ERα and ERβ. These transcription factors are differentially expressed within follicles, with ERβ being the predominant ER in GC. Several ERβ splice isoforms have been identified and display specific structural features, which greatly complicates the nature of ERβ-mediated E2 signaling. This review aims at providing a concise overview of the main actions of E2 during follicular growth, maturation, and selection in human. It also describes the current understanding of the various roles of ERβ splice isoforms, especially their influence on cell fate. We finally discuss how E2 signaling deregulation could participate in two ovarian pathogeneses characterized by either a follicular arrest, as in polycystic ovary syndrome, or an excess of GC survival and proliferation, leading to granulosa cell tumors. This review emphasizes the need for further research to better understand the molecular basis of E2 signaling throughout folliculogenesis and to improve the efficiency of ovarian-related disease therapies.

Estradiol Regulates mRNA Levels of Estrogen Receptor Beta 4 and Beta 5 Isoforms and Modulates Human Granulosa Cell Apoptosis

Estrogen receptor beta (ERβ) plays a critical role in granulosa cell (GC) functions. The existence of four human ERβ splice isoforms in the ovary suggests their differential implication in 17β-estradiol (E2) actions on GC apoptosis causing follicular atresia. In this study, we investigated whether E2 can regulate ERβ isoforms expression to fine tune its apoptotic activities in human GC. For this purpose, we measured by RT-qPCR the expression of ERβ isoforms in primary culture of human granulosa cells (hGCs) collected from patients undergoing in vitro fertilization, before and after E2 exposure. Besides, we assessed the potential role of ERβ isoforms on cell growth and apoptosis after their overexpression in a human GC line (HGrC1 cells). We confirmed that ERβ1, ERβ2, ERβ4, and ERβ5 isoform mRNAs were predominant over that of ERα in hGCs, and found that E2 selectively regulates mRNA levels of ERβ4 and ERβ5 isoforms in these cells. In addition, we demonstrated that overexpression of ERβ1 and ERβ4 in HGrC1 cells increased cell apoptosis by 225% while ERβ5 or ERβ2 had no effect. Altogether, our study revealed that E2 may influence GC fate by specifically regulating the relative abundance of ERβ isoforms mRNA to modulate the balance between pro-apoptotic and non-apoptotic ERβ isoforms.

The role of aromatase inhibitors in ameliorating deleterious effects of ovarian stimulation on outcome of infertility treatment

Clinical utilization of ovulation stimulation to facilitate the ability of a couple to conceive has not only provided a valuable therapeutic approach, but has also yielded extensive information on the physiology of ovarian follicular recruitment, endometrial receptivity and early embryo competency. One of the consequences of the use of fertility enhancing agents for ovarian stimulation has been the creation of a hyperestrogenic state, which may influence each of these parameters. Use of aromatase inhibitors reduces hyperestrogenism inevitably attained during ovarian stimulation. In addition, the adjunct use of aromatase inhibitors during ovarian stimulation reduces amount of gonadotropins required for optimum stimulation. The unique approach of reducing hyperestrogenism, as well as lowering amount of gonadotropins without affecting the number of mature ovarian follicles is an exciting strategy that could result in improvement in the treatment outcome by ameliorating the deleterious effects of the ovarian stimulation on follicular development, endometrial receptivity, as well as oocyte and embryo quality.

Effects of follicle-stimulating hormone administration on oestradiol-induced cystic ovaries in guinea pigs

A consistent defect in follicle-stimulating hormone (FSH) secretion is seen in humans with Polycystic Ovarian Syndrome (PCOS); therefore, we evaluated whether Metrodin (a highly purified urinary FSH) administration concurrent with cyst induction or following cyst induction inhibits estrogen-induced cyst development and augments ovarian follicular growth in an established guinea pig model. All animals in these studies received subcutaneous implants containing oestradiol-17 beta (E2)-filled Silastic capsules for a 48-hour period. Guinea pigs in study #1 were administered four 0.25 mL injections of FSH or placebo at twelve-hour intervals simultaneously with the E2 treatment; guinea pigs assigned to study #2 were administered four 0.25 mL injections of FSH or placebo at twelve-hour intervals following the induction of the cystic condition by E2. Exogenous FSH appears to negate cyst formation when superimposed upon the cyst-inducing agent (E2). Further, treatment with FSH augmented the number of mid-sized follicles in both paradigms. This study is the first to establish evidence of an anti-cystic effect of FSH in an animal model.