Mechanisms in the regulation of aromatase in developing ovary and placenta

The Differentiation Fate of Granulosa Cells and the Regulatory Mechanism in Ovary

Granulosa cells (GCs) are important drives of the reproductive process, not only the supporting cells for nutrition, but also cells with endocrine functions. Their differentiation and development parallel the entire menstruation period and even during pregnancy, making it tightly linked to the fate of the follicle. To elucidate the underlying mechanism is of great significance for related researches. The life course of GCs is briefly divided into five stages, from epithelial cells to pre-granulosa cells, GCs, mural and cumulus cells, lutein cells, and eventually disappear. A wide variety of genes and transcription factors participate in the regulation of different stages, and more importantly, various hormones secreted by the pituitary gland and GCs themselves play a leading role. These endogenous and exogenous signalling molecules interact to form a cross-linked communication network, promoting the development of GCs. Together with oocytes, theca cells and other functional cells in the ovary, GCs drive one of the most vital biological processes in women.

Orchestrated feedback regulation between melatonin and sex hormones involving GPER1-PKA-CREB signaling in the placenta

Maintaining placental endocrine homeostasis is crucial for a successful pregnancy. Pre-eclampsia (PE), a gestational complication, is a leading cause of maternal and perinatal morbidity and mortality. Aberrant elevation of testosterone (T0 ) synthesis, reduced estradiol (E2 ), and melatonin productions have been identified in preeclamptic placentas. However, the precise contribution of disrupted homeostasis among these hormones to the occurrence of PE remains unknown. In this study, we established a strong correlation between suppressed melatonin production and decreased E2 as well as elevated T0 synthesis in PE placentas. Administration of the T0 analog testosterone propionate (TP; 2 mg/kg/day) to pregnant mice from E7.5 onwards resulted in PE-like symptoms, along with elevated T0 production and reduced E2 and melatonin production. Notably, supplementation with melatonin (10 mg/kg/day) in TP-treated mice had detrimental effects on fetal and placental development and compromised hormone synthesis. Importantly, E2 , but not T0 , actively enhanced melatonin synthetase AANAT expression and melatonin production in primary human trophoblast (PHT) cells through GPER1-PKA-CREB signaling pathway. On the other hand, melatonin suppressed the level of estrogen synthetase aromatase while promoting the expressions of androgen synthetic enzymes including 17β-HSD3 and 3β-HSD1 in PHT cells. These findings reveal an orchestrated feedback mechanism that maintains homeostasis of placental sex hormones and melatonin. It is implied that abnormal elevation of T0 synthesis likely serves as the primary cause of placental endocrine disturbances associated with PE. The suppression of melatonin may represent an adaptive strategy to correct the imbalance in sex hormone levels within preeclamptic placentas. The findings of this study offer novel evidence that identifies potential targets for the development of innovative therapeutic strategies for PE.

Characterization of Xenobiotic and Steroid Disposition Potential of Human Placental Tissue and Cell Lines (BeWo, JEG-3, JAR, and HTR-8/SVneo) by Quantitative Proteomics

The placenta is a fetal organ that performs critical functions to maintain pregnancy and support fetal development, including metabolism and transport of xenobiotics and steroids between the maternal-fetal unit. In vitro placenta models are used to study xenobiotic and steroid disposition, but how well these models recapitulate the human placenta is not well understood. We first characterized the abundance of proteins involved in xenobiotic and steroid disposition in human placental tissue. In pooled human placenta, the following xenobiotic and steroid disposition proteins were detected (highest to lowest), 1) enzymes: glutathione S-transferase P, carbonyl reductase 1, aldo-keto reductase 1B1, hydroxysteroid dehydrogenases (HSD3B1 and HSD11B1), aromatase, epoxide hydrolase 1 (EPHX1) and steryl-sulfatase, and 2) transporters: monocarboxylate transporters (MCT1 and 4), organic anion transporting polypeptide 2B1, organic anion transporter 4, and breast cancer resistance protein (BCRP). Then, the tissue proteomics data were compared with four placental cell lines (BeWo, JEG-3, JAR, and HTR-8/SVneo). The differential global proteomics analysis revealed that the tissue and cell lines shared 1420 cytosolic and 1186 membrane proteins. Although extravillous trophoblast and cytotrophoblast marker proteins were detected in all cell lines, only BeWo and JEG-3 cells expressed the syncytiotrophoblast marker, chorionic somatomammotropin hormone 1. BeWo and JEG-3 cells expressed most target proteins including aromatase, HSDs, EPHX1, MCT1, and BCRP. JEG-3 cells treated with commonly detected phthalates in human biofluids showed dysregulation of steroid pathways. The data presented here show that BeWo and JEG-3 cells are closer to the placental tissue for studying xenobiotic and steroid disposition. SIGNIFICANCE STATEMENT: This is the first study to compare proteomics data of human placental tissue and cell lines (BeWo, JAR, JEG-3, and HTR-8/SVneo). The placental cell line and tissue proteomes are vastly different, but BeWo and JEG-3 cells showed greater resemblance to the tissue in the expression of xenobiotic and steroid disposition proteins. These data will assist researchers to select an optimum cell model for mechanistic investigations on xenobiotic and steroid disposition in the placenta.

Biochemical Screening for Fetal Trisomy 21: Pathophysiology of Maternal Serum Markers and Involvement of the Placenta

It is now well established that maternal serum markers are often abnormal in fetal trisomy 21. Their determination is recommended for prenatal screening and pregnancy follow-up. However, mechanisms leading to abnormal maternal serum levels of such markers are still debated. Our objective was to help clinicians and scientists unravel the pathophysiology of these markers via a review of the main studies published in this field, both in vivo and in vitro, focusing on the six most widely used markers (hCG, its free subunit hCGβ, PAPP-A, AFP, uE3, and inhibin A) as well as cell-free feto-placental DNA. Analysis of the literature shows that mechanisms underlying each marker's regulation are multiple and not necessarily directly linked with the supernumerary chromosome 21. The crucial involvement of the placenta is also highlighted, which could be defective in one or several of its functions (turnover and apoptosis, endocrine production, and feto-maternal exchanges and transfer). These defects were neither constant nor specific for trisomy 21, and might be more or less pronounced, reflecting a high variability in placental immaturity and alteration. This explains why maternal serum markers can lack both specificity and sensitivity, and are thus restricted to screening.

Immunoendocrine abnormalities in the female reproductive system, and lung steroidogenesis during experimental pulmonary tuberculosis

INTRODUCTION

Tuberculosis (TB) caused by Mycobacterium tuberculosis mainly affects the lungs, but can spread to other organs. TB chronically activates the immune and endocrine systems producing remarkable functional changes.So far, it is unknown whether pulmonary non-disseminated TB cause changes in the female reproductive system and lung endocrinology.

OBJECTIVE

To investigate whether pulmonary TB produces immunoendocrine alterations of the female mice reproductive organs, and lung estradiol synthesis.

METHODS

BALB/c mice were infected intratracheally with Mycobacterium tuberculosis (Mtb) strain H37Rv. Groups of six non-infected and infected animals were euthanized on different days. Bacillary loads were determined in the lungs, ovaries and uterus. Immunohistochemistry and morphometry studies were performed in histological sections. Serum estradiol wasassayed, and supernatantfrom cultured lung cells was analyzed by Thin Layer Chromatography (TLC).

RESULTS

Mtb only grew in lung tissue. Histopathology revealed abnormal folliculogenesis and decreased corpora lutea. Altered ovarian expression of IL-6, IL-1β was found. The infection increased serum estradiol. Estradiol synthesis by infected lung cells triplicate after 30 pi days.Aromatase immunostaining was found in the alveolar and bronchial epithelium, being stronger in the infected lungs, mainly in macrophages.

CONCLUSION

Pulmonary TB affects the histophysiology of the female reproductive system in absence of its local infection, and disturbslung endocrinology.

Effect of liver receptor homolog-1 on cell apoptosis and steroid hormone secretion on granulosa cells from Hu sheep

The apoptosis of granulosa cells can result in follicular atresia, a key process in follicle selection and development. The related molecular mechanisms were explored to study the effects of liver receptor homolog-1 (Lrh-1) on apoptosis, sodium-titanium system, and steroid synthesis of granulosa cells from Hu sheep in vitro. After constructing, designing, and synthesizing the Lrh-1 overexpression vector, liposomes were used to transfect Hu sheep granulosa cells. Thereafter, qRT-PCR and Western blot were used to detect the mechanism of Lrh-1 on the titanium system and steroid synthesis of Hu sheep granulosa cells. The overexpression efficiency was determined by fluorescence 48 h after liposome transfection into the Hu sheep granulosa cells in vitro culture. The transfection efficiency was higher, hence providing a basis for subsequent experiments. However, the protein level and transcriptional level of Lrh-1 significantly increased after transfection with Lrh-1 overexpression vector in Hu sheep granulosa cells. We further revealed that after Lrh-1 overexpression in Hu sheep granulosa cells, the expression of the pro-apoptotic gene Bax decreased significantly, while that of the anti-apoptotic gene Bcl-2 increased significantly, as well as the sodium peptide system. Moreover, the expression levels of natriuretic peptide precursor A, B, and C (NPPA, NPPB, NPPC) all showed an upward trend, while the expression levels of steroid synthesis-related genes (P450arom and P450scc) decreased. The above results showed that Lrh-1 overexpression influenced the apoptosis, sodium peptide system, and steroid synthesis.

Genetics of ovarian insufficiency and defects of folliculogenesis

Primary ovarian insufficiency (POI) is determined by exhaustion of follicles in the ovaries, which leads to infertility before the age of 40 years. It is characterized by a strong familial and heterogeneous genetic background. Therefore, we will mainly discuss the genetic basis of POI in this review. We identified 107 genes related to POI etiology in mammals described by several independent groups. Thirty-four of these genes (AARS2, AIRE, ANTXR1, ATM, BMPR1B, CLPP, CYP17A1, CYP19A1, DCAF17, EIF2B, ERAL1, FANCA, FANCC, FMR1, FOXL2, GALT, GNAS, HARS2, HSD17B4, LARS2, LMNA, MGME1, NBN, PMM2, POLG, PREPL, RCBTB1, RECQL2/3/4, STAR, TWNK, and XRCC4/9) have been linked to syndromic POI and are mainly implicated in metabolism function and meiosis/DNA repair. In addition, the majority of genes associated with nonsyndromic POI, widely expanded by high-throughput techniques over the last decade, have been implicated in ovarian development and meiosis/DNA repair pathways (ATG7, ATG9, ANKRD31, BMP8B, BMP15, BMPR1A, BMPR1B, BMPR2, BNC1, BRCA2, CPEB1, C14ORF39, DAZL, DIAPH2, DMC1, ERCC6, FANCL, FANCM, FIGLA, FSHR, GATA4, GDF9, GJA4, HELQ, HSF2BP, HFM1, INSL3, LHCGR, LHX8, MCM8, MCM9, MEIOB, MSH4, MSH5, NANOS3, NOBOX, NOTCH2, NR5A1, NUP107, PGRMC1, POLR3H, PRDM1, PRDM9, PSMC3IP, SOHLH1, SOHLH2, SPIDR, STAG3, SYCE1, TP63, UBR2, WDR62, and XRCC2), whereas a few are related to metabolic functions (EIF4ENIF1, KHDRBS1, MRPS22, POLR2C). Some genes, such as STRA8, FOXO3A, KIT, KITL, WNT4, and FANCE, have been shown to cause ovarian insufficiency in rodents, but mutations in these genes have yet to be elucidated in women affected by POI. Lastly, some genes have been rarely implicated in its etiology (AMH, AMHR2, ERRC2, ESR1, INHA, LMN4, POF1B, POU5F1, REC8, SMC1B). Considering the heterogeneous genetic and familial background of this disorder, we hope that an overview of literature data would reinforce that genetic screening of those patients is worthwhile and helpful for better genetic counseling and patient management.

Chromatin Accessibility and Transcriptomic Alterations in Murine Ovarian Granulosa Cells upon Deoxynivalenol Exposure

Deoxynivalenol (DON) is a common environmental toxin that is secreted by fusarium fungi that frequently contaminates feedstuff and food. While the detrimental effects of DON on human and animal reproductive systems have been well recognized, the underlying mechanism remains poorly understood. Ovarian granulosa cells (GCs), which surround oocytes, are crucial for regulating oocyte development, mainly through the secretion of hormones such as estrogen and progesterone. Using an in vitro model of murine GCs, we characterized the cytotoxic effects of DON and profiled genome-wide chromatin accessibility and transcriptomic alterations after DON exposure. Our results suggest that DON can induce decreased viability and growth, increased apoptosis rate, and disrupted hormone secretion. In total, 2533 differentially accessible loci and 2675 differentially expressed genes were identified that were associated with Hippo, Wnt, steroid biosynthesis, sulfur metabolism, and inflammation-related pathways. DON-induced genes usually have a concurrently increased occupancy of active histone modifications H3K4me3 and H3K27ac in their promoters. Integrative analyses identified 35 putative directly affected genes including Adrb2 and Fshr, which are key regulators of follicular growth, and revealed that regions with increased chromatin accessibility are enriched with the binding motifs for NR5A1 and NR5A2, which are important for GCs. Moreover, DON-induced inflammatory response is due to the activation of the NF-κB and MAPK signaling pathways. Overall, our results provide novel insights into the regulatory elements, genes, and key pathways underlying the response of ovarian GCs to DON cytotoxicity.

Regulation of aromatase expression: Potential therapeutic insight into breast cancer treatment

Estrogen signaling has been implicated in hormone-dependent breast cancer which constitutes >75% of breast cancer diagnosis and other malignancies. Aromatase, the key enzyme involved in the synthesis of estrogen, is often dysregulated in breast cancers. This has led to the administration of aromatase-inhibitors (AIs), commonly used for hormone-dependent breast cancers. Unfortunately, the increasing development of acquired resistance to the current AIs and modulators of estrogen receptors, following initial disease steadiness, has posed a serious clinical challenge in breast cancer treatment. In this review we highlight historical and recent advances on the transcriptional and post-translational regulation of aromatase in both physiological and pathological contexts. We also discuss the different drug combinations targeting various tumor promoting cell signaling pathways currently being developed and tested both in laboratory settings and in the clinic.

First trimester mechanisms of gestational sac placental and foetal teratogenicity: a framework for birth cohort studies

BACKGROUND

The function of the gestational sac (GS) and the placenta in the closely related processes of embryogenesis and teratogenicity in the first trimester has been minimally described. The prevailing assumption is that direct teratogenic effects are mediated by the critical extraembryonic organ, the placenta, which either blocks or transfers exposures to the foetus. Placental transfer is a dominant mechanism, but there are other paradigms by which the placenta can mediate teratogenic effects. Knowledge of these paradigms and first trimester human developmental biology can be useful to the epidemiologist in the conduct of biomarker-based studies of both maternal and child health.

OBJECTIVE AND RATIONALE

Our aim is to provide a causal framework for modelling the teratogenic effects of first trimester exposures on child health outcomes mediated by the GS and placenta using biomarker data collected in the first trimester. We initially present first trimester human developmental biology for the sake of informing and strengthening epidemiologic approaches. We then propose analytic approaches of modelling placental mechanisms by way of causal diagrams using classical non-embryolethal teratogens (diethylstilboestrol [DES], folic acid deficiency and cytomegalovirus [CMV]) as illustrative examples. We extend this framework to two chronic exposures of particular current interest, phthalates and maternal adiposity.

SEARCH METHODS

Information on teratogens was identified by a non-systematic, narrative review. For each teratogen, we included papers that answered the five following questions: (i) why were these exposures declared teratogens? (ii) is there a consensus on biologic mechanism? (iii) is there reported evidence of a placental mechanism? (iv) can we construct a theoretical model of a placental mechanism? and (v) can this knowledge inform future work on measurement and modelling of placental-foetal teratogenesis? We prioritized literature specific to human development, the organogenesis window in the first trimester and non-embryolethal mechanisms.

OUTCOMES

As a result of our review of the literature on five exposures considered harmful in the first trimester, we developed four analytic strategies to address first trimester placental mechanisms in birth cohort studies: placental transfer and direct effects on the foetus (DES and maternal adiposity), indirect effects through targeted placental molecular pathways (DES and phthalates), pre-placental effects through disruptions in embryonic and extraembryonic tissue layer differentiation (folic acid deficiency), and multi-step mechanisms that involve maternal, placental and foetal immune function and inflammation (DES and CMV).

WIDER IMPLICATIONS

The significance of this review is to offer a causal approach to classify the large number of potentially harmful exposures in pregnancy when the exposure occurs in the first trimester. Our review will facilitate future research by advancing knowledge of the first trimester mechanisms necessary for researchers to effectively associate environmental exposures with child health outcomes.

Upregulation of Cyp19a1 and PPAR-γ in ovarian steroidogenic pathway by Ficus religiosa: A potential cure for polycystic ovary syndrome

ETHNOPHARMACOLOGICAL RELEVANCE

Quite a few plants are in use to treat female infertility and associated problems. Availing the cues from traditional knowledge, phytochemical studies and ethnopharmacological evidences, the aphrodisiac plant Ficus religiosa (F. religiosa) is widely in use to cure infertility in women. For instance, the juice of leaf and aerial root of F. religiosa is reported to normalize the dysregulated menstrual cycle in women. Besides, it is believed that regular circumambulation of F. religiosa during the early hours of the morning helps women in alleviating infertility which could be attributed to the potential phytovolatiles released from F. religiosa. However, the evidences for therapeutic potential of F. religiosa in treating female infertility are arbitrary and mostly anecdotal.

AIM OF THE STUDY

The present study was aimed at examining if extracts of fresh and/or dry leaf of F. religiosa would cure polycystic ovary syndrome (PCOS) in the rat model.

METHODS

Rats were divided into seven groups; control (Group I), PCOS-induced (P.O, Letrozole -1 mg/kg BW for 21 days) and untreated (Group II), PCOS-induced and treated with the leaf extracts of F. religiosa (Groups III-VI), and, PCOS-induced and treated with pioglitazone (Group VII). The estrous intervals, body and organ weights (ovary and uterus), and serum hormones (testosterone, luteinizing hormone [LH], estrogen, and progesterone) were measured, and the expression of Cyp19a1 (aromatase), and Peroxisome Proliferator-Activated Receptor-γ (PPAR-γ) were assessed in the experimental rats. The levels of 3β-hydroxysteroid dehydrogenase (3β-HSD), 17β-hydroxysteroid dehydrogenase (17β-HSD), and antioxidants (MDA, GSH, GPx, SOD, and CAT) were also quantified. Besides, the putative volatile compounds in the esterified leaf extracts were identified using Gas Chromatography-Mass Spectrometry (GC-MS).

RESULTS

Letrozole treatment induced irregular estrous and altered weight of organs and hormonal milieu, which were reverted to normal in leaf extracts-treated PCOS-induced rats. Remarkably, fresh leaf treatment up-regulated Cyp19a1and PPAR-γ and increased the levels of 3β-HSD and 17β-HSD. We found 3-acetoxy-3-hydroxy-propionic acid in fresh and dry leaf extracts, which we attribute to efficacy of the extracts in alleviating PCOS.

CONCLUSION

Put together, our findings suggest the leaves of F. religiosa as potential in alleviating PCOS, mainly due to the presence of putative volatile molecules. Further screening of the leaves of F. religiosa is recommended to identify other key molecules and to develop a systematic therapeutic intervention for PCOS.

Effect of mice Taenia crassiceps WFU cysticerci infection on the ovarian folliculogenesis, enzyme expression, and serum estradiol

The murine infection with Taenia crassiceps WFU (T. crassiceps WFU) cysticerci has been widely used as an experimental model to better understand human cysticercosis. Several reports have established that the host hormonal environment determines the susceptibility and severity of many parasite infections. Female mice are more susceptible to infection with T. crassiceps cysticerci suggesting that a rich estrogen environment facilitates their reproduction. Ovarian androgens and estrogens are synthesized by key enzymes as P450-aromatase and 17α-hydroxilase/17, 20 lyase (P450_C17). The aim of this study was to determine the effect of chronic intraperitoneal infection of T. crassiceps WFU cysticerci on mice ovarian follicular development, ovulation, the expression of ovarian P450-aromatase and P450_C17, and serum 17β-estradiol, key enzymes of the ovarian steroidogenic pathway. To perform this study ovaries and serum were obtained at two, four and six months from T. crassiceps WFU cysticerci infected mice, and compared to those of healthy animals. The ovaries were fixed and processed for histology or lysed in RIPA buffer for Western blot using specific antibodies for P450_C17 and P450-aromatase. 17β-estradiol serum concentration was measured by ELISA. The results showed that the infection with T. crassiceps WFU cysticerci significantly reduced the number of primordial and primary follicles after two months of infection. Through the course of the study, the corpus luteum number began to decrease, whereas atretic follicles increased. The expression of ovarian P450_C17 and P450-aromatase as well as serum E2 concentration were significantly increased in the infected group compared to control. These findings show that chronic infection with Taenia crassiceps WFU may alter the reproductive functions of the female mice host.

Short-term effect of FSH on gene expression in bovine granulosa cells in vitro

In reproduction, FSH is one of the most important hormones, especially in females, because it controls the number of follicles and the rate of follicular growth. Although several studies have examined the follicular response at the transcriptome level, it is difficult to obtain a clear and complete picture of the genes responding to an increase in FSH in an in vivo context because follicles undergo rapid morphological and physical changes during their growth. To help define the transcriptome downstream response to FSH, an in vitro model was used in the present study to observe the short-term (4h) cellular response. Gene expression analysis highlighted a set of novel transcripts that had not been reported previously as being part of the FSH response. Moreover, the results of the present study indicate that the epithelial to mesenchymal transition pathway is inhibited by short-term FSH stimuli, maintaining follicles in a growth phase and preventing differentiation. Modulating gene expression in vitro has physiological limitations, but it can help assess the potential downstream response and begin the mapping of the granulosa cell transcriptome in relation to FSH. This information is a key feature to help discriminate between the effects of FSH and LH, or to elucidate the overlapping of insulin-like growth factor 1 and FSH in the granulosa mitogenic response.

Role of RAB5A in FSHR-mediated signal transduction in human granulosa cells

Polycystic ovary syndrome, a common condition characterized by endocrine dysfunction, menstrual irregularity, anovulation and polycystic ovaries, affects 5–7% of reproductive-age women. RAB5B, which is identified by a genome-wide association study as a risk locus for this syndrome, encodes a small GTPase involved in control of receptor internalization and early endosome fusion. We found that RAB5A mRNA levels in luteinized granulosa cells of obese patients with polycystic ovary syndrome were lower than in those of obese women without the syndrome. RAB5A regulated follicle-stimulating hormone (FSH)-mediated translocation of the FSH receptor (FSHR) from the membrane to the cytoplasm and the subsequent FSH–FSHR signaling pathway. We showed that RAB5A negatively regulated aromatase expression and estradiol synthesis in human granulosa cells in association with changes in FSHR levels by way of the cAMP/PKA/CREB pathway. The regulation of FSHR by RAB5A may have been associated with two transcription factors, USF1 and USF2. In conclusion, RAB5A gene was abnormally expressed in luteinized granulosa cells of obese patients with polycystic ovary syndrome, which may help explain high FSHR levels found in this syndrome.

miR-1275 controls granulosa cell apoptosis and estradiol synthesis by impairing LRH-1/CYP19A1 axis

miR-1275 is one of the microRNAs (miRNAs) that are differentially expressed during follicular atresia in pig ovaries, as identified by a miRNA microarray assay in our previous study [1]. However, its functions in follicular atresia remain unknown. In this study, we showed that miR-1275 promotes early apoptosis of porcine granulosa cells (pGCs) and the initiation of follicular atresia, and inhibits E2 release and expression of CYP19A1, the key gene in E2 production. Bioinformatics and luciferase reporter assays revealed that liver receptor homolog (LRH)-1, not CYP19A1, is a direct functional target of miR-1275. In vitro overexpression and knockdown experiments showed that LRH-1 significantly repressed apoptosis and induced E2 secretion and CYP19A1 expression in pGCs. LRH-1, whose expression was regulated by miR-1275, prevented apoptosis in pGCs. Furthermore, luciferase and chromatin immunoprecipitation assays demonstrated that LRH-1 protein bound to the CYP19A1 promoter and increased its activity. Our findings suggest that miR-1275 attenuates LRH-1 expression by directly binding to its 3'UTR. This prevents the interaction of LRH-1 protein with the CYP19A1 promoter, represses E2 synthesis, promotes pGC apoptosis, and initiates follicular atresia in porcine ovaries.

A homologue of Nr5a1 activates cyp19a1a transcription additively with Nr5a2 in ovarian follicular cells of the orange-spotted grouper

Transcription factors of nuclear receptor 5A (Nr5a) subfamily play pivotal roles in regulation of steroidogenic enzymes in vertebrates including teleosts. In the orange-spotted grouper, the expression of Nr5a1a was only detectable in the ovary, spleen, and head kidney in the female. The immunoreactive Nr5a1a was present in ovarian follicular and germ cells. In the ovarian follicular cells surrounding vitellogenic oocytes, Nr5a1a was detected both in the nucleus and cytoplasm, and co-localized with Cyp19a1a and Nr5a2. In the ovarian follicular cells surrounding fully grown oocytes, Nr5a1a was localized almost exclusively to the cytoplasm together with Nr5a2. Nr5a1a could up-regulate cyp19a1a promoter activities through Nr5a sites, and further increase the responses elicited by Nr5a2 at sub-maximal doses. Chromatin immunoprecipitation analysis showed that Nr5a1a bound to cyp19a1a promoter in the vitellogenic but not fully grown ovary. Taken together, Nr5a1a up-regulates cyp19a1a additively with Nr5a2 during vitellogenesis, and its cytoplasmic sequestration may also contribute to the down-regulation of cyp19a1a in the fully grown ovary.

Hormonal alterations in PCOS and its influence on bone metabolism

According to the World Health Organization (WHO) polycystic ovary syndrome (PCOS) occurs in 4-8% of women worldwide. The prevalence of PCOS in Indian adolescents is 12.2% according to the Indian Council of Medical Research (ICMR). The National Institute of Health has documented that it affects approximately 5 million women of reproductive age in the United States. Hormonal imbalance is the characteristic of many women with polycystic ovarian syndrome (PCOS). The influence of various endocrine changes in PCOS women and their relevance to bone remains to be documented. Hormones, which include gonadotrophin-releasing hormone (GnRH), insulin, the leutinizing/follicle-stimulating hormone (LH/FSH) ratio, androgens, estrogens, growth hormones (GH), cortisol, parathyroid hormone (PTH) and calcitonin are disturbed in PCOS women. These hormones influence bone metabolism in human subjects directly as well as indirectly. The imbalance in these hormones results in increased prevalence of osteoporosis in PCOS women. Limited evidence suggests that the drugs taken during the treatment of PCOS increase the risk of bone fracture in PCOS patients through endocrine disruption. This review is aimed at the identification of the relationship between bone mineral density and hormonal changes in PCOS subjects and identifies potential areas to study bone-related disorders in PCOS women.

Interactions between androgens, FSH, anti-Müllerian hormone and estradiol during folliculogenesis in the human normal and polycystic ovary

BACKGROUND

Androgens, FSH, anti-Müllerian hormone (AMH) and estradiol (E2) are essential in human ovarian folliculogenesis. However, the interactions between these four players is not fully understood.

OBJECTIVES AND RATIONALE

The purpose of this review is to highlight the chronological sequence of the appearance and function of androgens, FSH, AMH and E2 and to discuss controversies in the relationship between FSH and AMH. A better understanding of this interaction could supplement our current knowledge about the pathophysiology of the polycystic ovary syndrome (PCOS).

SEARCH METHODS

A literature review was performed using the following search terms: androgens, FSH, FSH receptor, anti-Mullerian hormone, AMHRII, estradiol, follicle, ovary, PCOS, aromatase, granulosa cell, oocyte. The time period searched was 1980-2015 and the databases interrogated were PubMed and Web of Science.

OUTCOMES

During the pre-antral ('gonadotropin-independent') follicle growth, FSH is already active and promotes follicle growth in synergy with theca cell-derived androgens. Conversely, AMH is inhibitory by counteracting FSH. We challenge the hypothesis that AMH is regulated by androgens and propose rather an indirect effect through an androgen-dependent amplification of FSH action on granulosa cells (GCs) from small growing follicles. This hypothesis implies that FSH stimulates AMH expression. During the antral ('gonadotropin-dependent') follicle growth, E2 production results from FSH-dependent activation of aromatase. Conversely, AMH is inhibitory but the decline of its expression, amplified by E2, allows full expression of aromatase, characteristic of the large antral follicles. We propose a theoretical scheme made up of two triangles that follow each other chronologically. In PCOS, pre-antral follicle growth is excessive (triangle 1) because of intrinsic androgen excess that renders GCs hypersensitive to FSH, with consequently excessive AMH expression. Antral follicle growth and differentiation are disturbed (triangle 2) because of the abnormally persisting inhibition of FSH effects by AMH that blocks aromatase. Beside anovulation, this scenario may also serve to explain the higher receptiveness to gonadotropin therapy and the increased risk of ovarian hyperstimulation syndrome (OHSS) in patients with PCOS.

WIDER IMPLICATIONS

Within GCs, the balance between FSH and AMH effects is pivotal in the shift from androgen- to oestrogen-driven follicles. Our two triangles hypothesis, based on updated data from the literature, offers a pedagogic template for the understanding of folliculogenesis in the normal and polycystic ovary. It opens new avenues for the treatment of anovulation due to PCOS.

Aetiological coding sequence variants in non-syndromic premature ovarian failure: From genetic linkage analysis to next generation sequencing

Premature ovarian failure (POF) is a frequent pathology affecting 1-1.5% of women under 40 years old. Despite advances in diagnosing and treating human infertility, POF is still classified as being idiopathic in 50-80% of cases, strongly suggesting a genetic origin for the disease. Different types of autosomal and X-linked genetic anomalies can originate the phenotype in syndromic and non-syndromic POF cases. Particular interest has been focused on research into non-syndromic POF causative coding variants during the past two decades. This has been based on the assumption that amino acid substitutions might modify the intrinsic physicochemical properties of functional proteins, thereby inducing pathological phenotypes. In this case, a restricted number of mutations might originate the disease. However, like other complex pathologies, POF might result from synergistic/compensatory effects caused by several low-to-mildly drastic mutations which have frequently been classified as non-functional SNPs. Indeed, reproductive phenotypes can be considered as quantitative traits resulting from the subtle interaction of many genes. Although numerous sequencing projects have involved candidate genes, only a few coding mutations explaining a low percentage of cases have been described. Such apparent failure to identify aetiological coding sequence variations might have been due to the inherent molecular complexity of mammalian reproduction and to the difficulty of simultaneously analysing large genomic regions by Sanger sequencing. The purpose of this review is to present the molecular and cellular effects caused by non-synonymous mutations which have been formally associated, by functional tests, with the aetiology of hypergonadotropic non-syndromic POF. Considerations have also been included regarding the polygenic nature of reproduction and POF, as well as future approaches for identifying novel aetiological genes based on next generation sequencing (NGS).

Possible intracellular regulators of female sexual maturation

Protein kinases, transcription factors and other apoptosis- and proliferation-related proteins can regulate reproduction, but their involvement in sexual maturation remains to be elucidated. The general aim of the in vivo and in vitro experiments with porcine ovarian granulosa cells was to identify possible intracellular regulators of female sexual maturation. For this purpose, proliferation (expression of proliferating cell nuclear antigen - PCNA, mitogen-activated protein kinases - ERK 1,2 related MAPK and cyclin B1), apoptosis (expression of the apoptotic protein Bax and apoptosis regulator Bcl-2 protein), expression of some protein kinases (cAMP dependent protein kinase - PKA, cGMP-dependent protein kinase - PKG, tyrosine kinase - TK) and cAMP responsive element binding protein 1 (CREB-1) was examined in granulosa cells isolated from ovaries of immature and mature gilts. Expression of PCNA, ERK1,2 related MAPK, cyclin B1, Bcl-2, Bax, PKA, CREB-1, TK and PKG in porcine granulosa cells were detected by immunocytochemistry. Sexual maturation was associated with significant increase in the expression of Bcl-2, Bax, PKA, CREB-1 and TK and with decrease in the expression of ERK1,2 related MAPK, cyclin B1 and PKG in granulosa cells. No significant difference in PCNA expression was noted. The present data obtained from in vitro study indicate that sexual maturation in females is influenced by puberty-related changes in porcine ovarian signaling substances: increase in Bcl-2, Bax, PKA, CREB-1, TK and decrease in ERK1,2 related MAPK, cyclin B1 and PKG. It suggests that these signaling molecules could be potential regulators of porcine sexual maturation.

Calcineurin and CRTC2 mediate FSH and TGFβ1 upregulation of Cyp19a1 and Nr5a in ovary granulosa cells

Estrogens are essential for female reproduction and overall well-being, and estrogens in the circulation are largely synthesized in ovarian granulosa cells. Using primary cultures of ovarian granulosa cells from gonadotropin-primed immature rats, we have recently discovered that pituitary FSH and ovarian cytokine transforming growth factor beta 1 (TGFβ1) induce calcineurin-mediated dephosphorylation-activation of cAMP-response element-binding protein (CREB)-regulated transcription coactivator (CRTC2) to modulate the expression of Star, Cyp11a1, and Hsd3b leading to increased production of progesterone. This study explored the role of calcineurin and CRTC2 in FSH and TGFβ1 regulation of Cyp19a1 expression in granulosa cells. Ovarian granulosa cells treated with FSH displayed increased aromatase protein at 24  h post-treatment, which subsided by 48  h, while TGFβ1 acting through its type 1 receptor augmented the action of FSH with a greater and longer effects. It is known that the ovary-specific Cyp19a1 PII-promoter contains crucial response elements for CREB and nuclear receptor NR5A subfamily liver receptor homolog 1 (LRH1/NR5A2) and steroidogenic factor 1 (SF1/NR5A1), and that the Nr5a2 promoter also has a potential CREB-binding site. Herein, we demonstrate that FSH+TGFβ1 increased LRH1 and SF1 protein levels, and their binding to the Cyp19a1 PII-promoter evidenced, determined by chromatin immunoprecipitation analysis. Moreover, pretreatment with calcineurin auto-inhibitory peptide (CNI) abolished the FSH+TGFβ1-upregulated but not FSH-upregulated aromatase activity at 48  h, and the corresponding mRNA changes in Cyp19a1, and Nr5a2 and Nr5a1 at 24  h. In addition, FSH and TGFβ1 increased CRTC2 binding to the Cyp19a1 PII-promoter and Nr5a2 promoter at 24  h, with CREB bound constitutively. In summary, the results of this study indicate that calcineurin and CRTC2 have important roles in mediating FSH and TGFβ1 collateral upregulation of Cyp19a1 expression together with its transcription regulators Nr5a2 and Nr5a1 in ovarian granulosa cells.

Post-translational dual regulation of cytochrome P450 aromatase at the catalytic and protein levels by phosphorylation/dephosphorylation

The post-translational regulation of aromatase has not been well characterized as compared with transcriptional regulation. Several studies of post-translational regulation have focused on decreases in catalytic activity following phosphorylation. We report here dual post-translational regulation of aromatase, at the catalytic activity and protein levels. Microsomal aromatase prepared from JEG-3 cells was rapidly inactivated and subsequently degraded in the presence of a cytosolic fraction with calcium, magnesium, and ATP. In a reconstituted system consisting of microsomal and cytosolic fractions, aromatase was protected from protein degradation by treatment with alkaline phosphatase, whereas degradation was enhanced by treatment with calcineurin inhibitors (FK506 and cyclosporin A). Furthermore, aromatase was protected from degradation by treatment with kinase inhibitors, especially the calcium/calmodulin kinase inhibitors KN62 and KN93. Similarly to the reconstituted system, aromatase in cultured JEG-3 cells was protected from degradation by KN93, whereas FK503 increased degradation in the presence of cycloheximide, although cellular aromatase mRNA levels were unchanged by these reagents. Knockdown of calcineurin and calcium/calmodulin kinase II (CaMKII) with small interfering RNAs resulted in a dose-dependent increase in aromatase degradation and protection from degradation, respectively. The cytosol fraction-dependent phosphorylation of microsomal aromatase was inhibited by calcineurin, KN62, and KN93, and promoted by CaMKII and FK506. These results indicate that aromatase is regulated acutely at the catalytic activity level and subsequently at the enzyme content level by CaMKII/calcineurin-dependent phosphorylation/dephosphorylation.

The orphan nuclear receptor Nr5a2 is essential for luteinization in the female mouse ovary

In the ovary, the follicular granulosa cells express the nuclear receptor Nr5a2 (nuclear receptor subfamily 5 group A member 2), also known as liver receptor homolog-1, and after ovulation, Nr5a2 expression persists in the corpus luteum. Previous studies demonstrated that Nr5a2 is required for both ovulation and luteal steroid synthesis. Our objectives were to analyze the temporal sequence in the regulatory effects of Nr5a2 in the ovary, with focus on its contribution to luteal function. We developed a female mouse model of granulosa-specific targeted disruption from the formation of the antral follicles forward (genotype Nr5a2(Cyp19-/-)). Mice lacking Nr5a2 in granulosa cells of antral follicles are infertile. Although their cumulus cells undergo expansion after gonadotropin stimulation, ovulation is disrupted in those mice, at least in part, due to the down-regulation of the progesterone receptor (Pgr) gene. The depletion of Nr5a2 in antral follicles permits formation of luteal-like structures but not functional corpora lutea, as evidenced by reduced progesterone levels and failure to support pseudopregnancy. Progesterone synthesis is affected by depletion of Nr5a2 due to, among others, defects in the transport of cholesterol, evidenced by down-regulation of Scarb1, Ldlr, and Star. Comparison of this mouse line with the models in which Nr5a2 is depleted from the primary follicle forward (genotype Nr5a2(Amhr2-/-)) and after the ovulatory signal (genotype Nr5a2(Pgr-/-)) demonstrates that Nr5a2 differentially regulates female fertility across the trajectory of follicular development.

Activation of endocrine-related gene expression in placental choriocarcinoma cell lines following DNA methylation knock-down

Increasingly, placental DNA methylation is assessed as a factor in pregnancy-related complications, yet the transcriptional impact of such findings is not always clear. Using a proliferative in vitro placental model, the effect of DNA methylation loss on gene activation was evaluated at a number of genes selected for being differentially methylated in pre-eclampsia-associated placentae in vivo. We aimed to determine whether reduced DNA methylation at specific loci was associated with transcriptional changes at the corresponding gene, thus providing mechanistic underpinnings for previous clinical findings and to assess the degree of transcriptional response amongst our candidate genes. BeWo and JEG3 choriocarcinoma cells were exposed to 1 μM 5-Aza-2'-deoxycytidine (5-Aza-CdR) or vehicle control for 48 h, and re-plated and cultured for a further 72 h in normal media before cells were harvested for RNA and DNA. Bisulphite pyrosequencing confirmed that DNA methylation was reduced by ∼30-50% points at the selected loci studied in both cell lines. Gene activation, measured by qRT-PCR, was highly variable and transcript specific, indicating differential sensitivity to DNA methylation. Most notably, loss of DNA methylation at the leptin (LEP) promoter corresponded to a 200-fold and 40-fold increase in LEP expression in BeWo and JEG3 cells, respectively (P < 0.01). Transcripts of steroidogenic pathway enzymes CYP11A1 and HSD3B1 were up-regulated ∼40-fold in response to 5-Aza-CdR exposure in BeWo cells (P < 0.01). Other transcripts, including aromatase (CYP19), HSD11B2, inhibin (INHBA) and glucocorticoid receptor (NR3C1) were more moderately, although significantly, affected by loss of associated DNA methylation. These data present a mixed effect of DNA methylation changes at selected loci supporting cautionary interpretation of DNA methylation results in the absence of functional data.

Novel NR5A1 missense mutation in premature ovarian failure: detection in han chinese indicates causation in different ethnic groups

Background

The etiology of most premature ovarian failure (POF) cases is usually elusive. Although genetic causes clearly exist and a likely susceptible region of 8q22.3 has been discovered, no predominant explanation exists for POF. More recently, evidences have indicated that mutations in NR5A1 gene could be causative for POF. We therefore screened for mutations in the NR5A1 gene in a large cohort of Chinese women with non-syndromic POF.

Methods

Mutation screening of NR5A1 gene was performed in 400 Han Chinese women with well-defined 46,XX idiopathic non-syndromic POF and 400 controls. Subsequently, functional characterization of the novel mutation identified was evaluated in vitro.

Results

A novel heterozygous missense mutation [c.13T>G (p.Tyr5Asp)] in NR5A1 was identified in 1 of 384 patients (0.26%). This mutation impaired transcriptional activation on Amh, Inhibin-a, Cyp11a1 and Cyp19a1 gene, as shown by transactivation assays. However, no dominant negative effect was observed, nor was there impact on protein expression and nuclear localization.

Conclusions

This novel mutation p.Tyr5Asp, in a novel non-domain region, is presumed to result in haploinsufficiency. Irrespectively, perturbation in NR5A1 is not a common explanation for POF in Chinese.

Early onset pre-eclampsia is associated with altered DNA methylation of cortisol-signalling and steroidogenic genes in the placenta

Placental cortisol is inactivated in normotensive pregnancies, but is frequently present in pre-eclampsia associated placentae. Since glucocorticoids are strongly associated with the programming of long-term health, we assessed DNA methylation of genes involved in cortisol signalling and bioavailability, and hormonal signalling in the placenta of normotensive and hypertensive pregnancies. Candidate genes/CpG sites were selected through analysis of Illumina Infinium HumanMethylation450 BeadChip array data on control (n = 19) and early onset pre-eclampsia (EOPET; n = 19) placental samples. DNA methylation was further quantified by bisulfite pyrosequencing in a larger cohort of control (n = 111) cases, in addition to EOPET (n = 19), late onset pre-eclampsia (LOPET; n = 18) and normotensive intrauterine growth restriction (nIUGR; n = 13) cases. DNA methylation (percentage points) was increased at CpG sites within genes encoding the glucocorticoid receptor (NR3C1 exon 1D promoter; +8.46%; P<0.01) and corticotropin releasing hormone (CRH) binding protein (CRHBP intron 3; +9.14%; P<0.05), and decreased within CRH (5' UTR; -4.30%; P = 0.11) in EOPET-associated placentae, but not in LOPET nor nIUGR cases, compared to controls. Differential DNA methylation was not observed among groups at the 11β-hydroxysteroid dehydrogenase type 2 (HSD11B2) gene promoter. Significant hypomethylation was observed in pre-eclampsia but not nIUGR placentae for steroidogenic genes, including CYP11A1 (exon1; EOPET; -9.66%; P<0.00001, and LOPET; -5.77%; P<0.001), 3β-hydroxy-delta-5-steroid dehydrogenase type 1 (HSD3B1 exon 2; EOPET; -12.49%; P<0.00001, and LOPET; -6.88%; P<0.001), TEA domain family member 3 (TEAD3 intron 1; EOPET; -12.56%; P<0.00001) and CYP19 (placental-specific exon 1.1 promoter; EOPET; -10.62%, P<0.0001). These data represent dysregulation of the placental epigenome in pre-eclampsia related to genes involved in maintaining the hormonal environment during pregnancy and highlights particular susceptibility in the early onset syndrome.

Emerging roles for LXRs and LRH-1 in female reproduction

Nutritional status is known to control female reproductive physiology. Many reproductive pathologies such as anorexia nervosa, dystocia and preeclampsia, have been linked to body mass index and to metabolic syndrome. Lipid metabolism has also been associated with ovarian, uterine and placental functions. Among the regulators of lipid homeostasis, the Liver X Receptors (LXRs) and the Liver Receptor Homolog-1 (LRH-1), two members of the nuclear receptor superfamily, play a central role. LXRs are sensitive to intracellular cholesterol concentration and decrease plasma cholesterol, allowing to considering them as "cholesterol sensors". LRH-1 shares many target-genes with LXRs and has been considered for a long time as a real orphan nuclear receptor, but recent findings showed that phospholipids are ligands for this nuclear receptor. Acting in concert, LXRs and LRH-1 could thus be sensitive to slight modifications in cellular lipid balance, tightly maintaining their cellular concentrations. These last years, the use of transgenic mice clarified the roles of these nuclear receptors in many physiological functions. This review will be focused on the roles of LXRs and LRH-1 on female reproduction. Their contribution to ovarian endocrine and exocrine functions, as well as uterine and placental physiology will be discussed. The future challenge will thus be to target these nuclear receptors to prevent lipid-associated reproductive diseases in women.

Tissue physiology and pathology of aromatase

Aromatase is expressed in multiple tissues, indicating a crucial role for locally produced oestrogens in the differentiation, regulation and normal function of several organs and processes. This review is an overview of the role of aromatase in different tissues under normal physiological conditions and its contribution to the development of some oestrogen-related pathologies.

Contemporary genetic technologies and female reproduction

BACKGROUND

The Fifth Evian Annual Reproduction (EVAR) Workshop Meeting discussed knowledge regarding contemporary genetics in female reproduction.

METHODS

Specialist reproductive medicine clinicians and geneticists delivered presentations based on published literature and current research. The content of this report is based on the expert presentations and subsequent group discussions that took place during this Workshop.

RESULTS

Numerous ovarian genes with a role in infertility have been identified. Future challenges for genetic screening of patients, such as those with polycystic ovary syndrome, primary ovarian insufficiency or endometriosis, include the identification of high-throughput strategies and how to apply these findings to infertile patients. The identification of high-quality embryos in IVF using objective technologies remains a high priority in order to facilitate single-embryo transfer. Gene expression profiling of cumulus cells surrounding the oocyte, and proteomic and metabolomic approaches in embryo culture media may significantly improve non-invasive embryo quality assessment.

CONCLUSIONS

The way forward in advancing the knowledge of genes involved in reproduction was considered to be through genome-wide association studies involving large numbers of patients. Establishing international collaboration is required to enable the application of such technologies in sufficient numbers of patients.

Stimulation of serotonergic 5-HT2A receptor signaling increases placental aromatase (CYP19) activity and expression in BeWo and JEG-3 human choriocarcinoma cells

It is known that serotonin can influence the production and function of sex hormones, such as estrogens. Estrogens are critical for maintenance of pregnancy and regulate placental and fetal development. The key enzyme controlling estrogens synthesis during pregnancy is placental aromatase (CYP19). To better understand the regulation of placental aromatase, this study determined whether serotonin is involved in the regulation of this enzyme. BeWo and JEG-3 choriocarcinoma cells were used as models of the human placental trophoblast to evaluate the effects of serotonin and selective 5-HT(2A) receptor agonists on CYP19 activity and expression. Serotonin and selective 5-HT(2A) receptor agonists as well as PKC activation increased aromatase activity and expression in BeWo and JEG-3 cells. Dexamethasone, which regulates aromatase expression via JAK/STAT activation in certain tissues, had no effect. Increased CYP19 gene transcription by 5-HT(2A) receptor and PKC stimulation was mediated by activation of the placental I.1 aromatase promoter. This study shows that the serotonergic system modulates placental aromatase expression, which would result in altered estrogens biosynthesis in trophoblast cells. Future detailed studies of serotonin-estrogen interactions in placenta are crucial for an improved understanding of the endo-, para- and autocrine role of serotonin during pregnancy and fetal development.

Prenatal androgen treatment alters body composition and glucose homeostasis in male rats

Prenatal androgen produces many reproductive and metabolic features of polycystic ovary syndrome in female rodents, sheep, and monkeys. We investigated the impact of such prenatal treatment in adult male rats. Pregnant dams received free testosterone (T; aromatizable androgen), dihydrotestosterone (D; nonaromatizable androgen), or vehicle control (C) on embryonic days 16-19. Neither of the prenatal androgen treatments resulted in increased body weight from weaning to age 65 days in males. However, at 65 days, there were significant increases in retroperitoneal (P < 0.001 T versus C; P < 0.05 D versus C), epididymal (P < 0.05 T versus C), and subcutaneous (P < 0.01 T versus C) fat pads in prenatally androgenized males. While both androgens altered body composition, subcutaneous fat depots increased only in T males. T males had elevated glucose levels (P < 0.01) compared to C males. There were no differences among the three groups in insulin sensitivity, circulating lipid and leptin levels, or hepatic triglyceride content. Real-time PCR analysis of insulin signaling pathway genes in retroperitoneal fat revealed a transcriptional downregulation of adipsin and insulin receptor substrate-1 in T and α-1D adrenergic receptor in D compared to C males. We conclude that transient exposure to androgen excess in utero increases body fat in adult male rats. Only T males exhibit increased circulating glucose levels and subcutaneous fat suggesting that these changes may be mediated by aromatization of androgen to estrogen rather than by direct androgenic actions.

BRCA1/BARD1 complex interacts with steroidogenic factor 1--A potential mechanism for regulation of aromatase expression by BRCA1

Germline mutations in BRCA1 predispose women to early onset of breast and ovarian cancers. Findings from previous studies support the notion that the tissue- and gender-specific tumor suppression function of BRCA1 is associated with its role in negative regulation of aromatase expression, the rate-limiting step in estrogen biosynthesis. The molecular mechanism of BRCA1 in regulating aromatase promoter activity remains to be elucidated. In this study, we demonstrate that, in an ovarian granulosa cell line KGN, steroidogenic factor 1 (SF-1) is required for aromatase PII promoter basal activity as well as the elevated aromatase expression mediated by BRCA1 knockdown. Furthermore, BRCA1 in KGN cells exists mainly as a heterodimer with BARD1. We provide evidence that the BRCA1/BARD1 complex interacts with SF-1 both in vivo and in vitro. However, the intrinsic ubiquitin E3 ligase activity of BRCA1/BARD1 does not appear to contribute to ubiquitynation of SF-1. We propose that the interaction between SF-1 and BRCA1/BARD1 may recruit BRCA1/BARD1 complex to the aromatase PII promoter for BRCA1/BARD1-mediate transcriptional repression.

Molecular regulation of human placental growth factor (PlGF) gene expression in placental villi and trophoblast cells is mediated via the protein kinase a pathway

Cyclic 3',5'-adenosine monophosphate (cAMP) is a critical second messenger for human trophoblasts and regulates the expression of numerous genes. It is known to stimulate in vitro the fusion and differentiation of BeWo choriocarcinoma cells, which acquire characteristics of syncytiotrophoblasts. A DNA microarray analysis of BeWo cells undergoing forskolin-induced syncytialization revealed that among the induced genes, placental growth factor (PlGF) was 10-fold upregulated. We verified this result in two choriocarcinoma cell lines, BeWo and JEG-3, and also in first trimester placental villous explants by quantifying PlGF mRNA (real time PCR) and PlGF protein secreted into the supernatant (ELISA). Similar effects were noted for vascular endothelial growth factor (VEGF) mRNA and protein expression. Treatment with cholera toxin and the use of a specific inhibitor of protein kinase A (PKA) blocked these effects, indicating that the cAMP/PKA pathway is responsible for the cAMP-induced upregulation of PlGF and that one or more G protein coupled receptor(s) was involved. We identified two functional cAMP responsive elements (CRE) in the PlGF promoter and demonstrated that the CRE binding protein, CREB, contributes to the regulation of PlGF gene expression. We speculate that defects in this signaling pathway may lead to abnormal secretion of PlGF protein as observed in the pregnancy-related diseases preeclampsia and intrauterine growth restriction.

Development and hormonal regulation of the ovarian lymphatic vasculature

The lymphatic vasculature plays a number of essential physiological roles including maintaining fluid homeostasis, providing a network for the transport of immune cells, and facilitating the uptake of fat-soluble nutrients from the gastrointestinal tract. Although the critical importance and remodeling capacity of the blood vasculature has been well described within the ovary, just a few reports describe the lymphatic vasculature. Using histological and molecular techniques, we report the kinetics of ovarian lymphangiogenesis and the hormonal regulation of lymphangiogenic growth factors associated with key stages of ovarian follicle growth. We exploited the Adamts1-null mouse model, a model with a previously characterized lymphatic defect to further interrogate the mechanisms controlling ovarian lymphangiogenesis. The establishment and development of the ovarian lymphatic vascular network in postnatal developing ovaries was associated with the presence and hormonal regulation of the lymphangiogenic growth factors and their receptors, including Vegfc, Vegfd, and Vegfr3. We characterized the hormonally regulated remodeling of the ovarian lymphatic vasculature in response to FSH and estradiol. The lymphatic network was defective in the Adamts1-null ovary, clearly demonstrating both the involvement of FSH/estradiol and the Adamts1 (a disintegrin and metalloproteinase with thrombospondin motifs 1) protease in ovarian lymphangiogenesis. This study provides the first evidence of a malleable lymphatic system responsive to hormonal changes of the female reproductive cycle, at least in the mouse ovary, suggesting a role for lymphatic vessel functions in normal folliculogenesis.

Insulin and hyperandrogenism in women with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a very common endocrine disorder characterized by chronic anovulation, clinical and/or biochemical hyperandrogenism, and/or polycystic ovaries. But most experts consider that hyperandrogenism is the main characteristic of PCOS. Several theories propose different mechanisms to explain PCOS manifestations: (1) a primary enzymatic default in the ovarian and/or adrenal steroidogenesis; (2) an impairment in gonadotropin releasing hormone (GnRH) secretion that promotes luteal hormone (LH) secretion; or (3) alterations in insulin actions that lead to insulin resistance with compensatory hyperinsulinemia. However, in the past 20 years there has been growing evidence supporting that defects in insulin actions or in the insulin signalling pathways are central in the pathogenesis of the syndrome. Indeed, most women with PCOS are metabolically insulin resistant, in part due to genetic predisposition and in part secondary to obesity. But some women with typical PCOS do not display insulin resistance, which supports the hypothesis of a genetic predisposition specific to PCOS that would be revealed by the development of insulin resistance and compensatory hyperinsulinemia in most, but not all, women with PCOS. However, these hypotheses are not yet appropriately confirmed, and more research is still needed to unravel the true pathogenesis underlying this syndrome. The present review thus aims at discussing new concepts and findings regarding insulin actions in PCOS women and how it is related to hyperandrogenemia.

[NR5A1 and ovarian failure]

Primary ovarian insufficiency (POI) is characterised by the arrest of normal ovarian function before the age of 40 years and affects 1 % of all women. POI shows familial inheritance suggesting a genetic contribution. NR5A1 is nuclear receptor that regulates the transcription of many genes involved in sexual developmental and reproduction. 18 NR5A1 mutations have been published associated with either anomalies of adrenal or testis development. We have identified NR5A1 mutations associated with POI, including familial cases with affected 46,XY individuals. This demonstrates that NR5A1 plays an important role in ovarian development and function. However several questions remain. What is the incidence of NR5A1 mutations in POI? Is there a genotype/phenotype relationship? Are mutations associated with a progressive loss of reproductive function? Answering these questions will lead to a better understanding of ovarian function and dysfunction and could lead to new therapies for treating POI.

Transforming growth factor-beta inhibits aromatase gene transcription in human trophoblast cells via the Smad2 signaling pathway

BACKGROUND

Transforming growth factor-beta (TGF-beta) is known to exert multiple regulatory functions in the human placenta, including inhibition of estrodial production. We have previously reported that TGF-beta1 decreased aromatase mRNA levels in human trophoblast cells. The objective of this study was to investigate the molecular mechanisms underlying the regulatory effect of TGF-beta1 on aromatase expression.

METHODS

To determine if TGF-beta regulates aromatase gene transcription, several reporter constructs containing different lengths of the placental specific promoter of the human aromatase gene were generated. JEG-3 cells were transiently transfected with a promoter construct and treated with or without TGF-beta1. The promoter activity was measured by luciferase assays. To examine the downstream signaling molecule mediating the effect of TGF-beta on aromatase transcription, cells were transiently transfected with dominant negative mutants of TGF-beta type II (TbetaRII) and type I receptor (ALK5) receptors before TGF-beta treatment. Smad2 activation was assessed by measuring phophorylated Smad2 protein levels in cytosolic and nuclear fractions. Smad2 expression was silenced using a siRNA expression construct. Finally, aromatase mRNA half-life was determined by treating cells with actinomycin D together with TGF-beta1 and measuring aromatase mRNA levels at various time points after treatment.

RESULTS AND DISCUSSION

TGF-beta1 inhibited the aromatase promoter activity in a time- and dose-dependent manner. Deletion analysis suggests that the TGF-beta1 response element resides between -422 and -117 nucleotides upstream from the transcription start site where a Smad binding element was found. The inhibitory effect of TGF-beta1 was blocked by dominant negative mutants of TbetaRII and ALK5. TGF-beta1 treatment induced Smad2 phosphorylation and translocation into the nucleus. On the other hand, knockdown of Smad2 expression reversed the inhibitory effect of TGF-beta1 on aroamtase transcription. Furthermore, TGF-beta1 accelerated the degradation of aromatase mRNA.

CONCLUSION

Our results demonstrate that TGF-beta1 exerts regulatory effects on aromatase gene at both transcriptional and post-transcriptional levels. The transcriptional regulation of aromatase gene by TGF-beta1 is mediated by the canonical TGF-beta pathway involving TbetaRII, ALK5 and Smad2. These findings further support the role of TGF-beta1 in regulating human placental functions and pregnancy.

Gonadotropin releasing hormone antagonists suppress aromatase and anti-Müllerian hormone expression in human granulosa cells

OBJECTIVE

To investigate the effects of a gonadotropin-releasing hormone antagonist (GnRH-ANT) on the expression of anti-Müllerian Hormone (AMH) and aromatase (via the exon CYP19IIa promoter), in cultured human granulosa cells (hGCs) and the human granulosa cell line (HGL5).

DESIGN

Primary cell cultures of hGCs and culture of HGL5 cells.

SETTING

Academic center.

PATIENT(S)

Women undergoing IVF because of male factor, tubal infertility, or donor eggs.

INTERVENTION(S)

hGCs and HGL5 cells were treated with a GnRH-ANT (1 nM and 1 μM) alone or in combination with cAMP (1 mM). Media was collected and stored at -80°C until assayed.

MAIN OUTCOME MEASURE(S)

mRNA levels of CYP19 IIa, AMH, steroidogenic factor 1 (SF-1) and liver receptor homologue-1 (LRH-1) were determined by quantitative polymerase chain reaction. ELISA was used to determined estradiol (E(2)) levels in the culture media. Pooled results from triplicate experiments were analyzed using one-way analysis of variance with Student-Newman-Keuls multiple-comparison methods.

RESULT(S)

The GnRH-ANT decreased the expressions of CYP19 IIa, AMH, SF-1, and LRH-1. cAMP induced aromatase and AMH expression. Cotreatment with cAMP and GnRH-ANT caused a dose-dependent suppression of AMH and CYP19 IIa mRNA. A GnRH agonist (GnRH-A) increased the mRNA expressions of CYP 19 IIa and AMH. The GnRH-ANT decreased E(2) production in cultured hGCs.

CONCLUSION(S)

GnRH-ANTs, in addition to their central suppressive effects on the pituitary, may have a direct effect on ovarian granulosa cells with inhibition of aromatase and AMH expression. Furthermore, the inhibitory effect could be mediated via suppression of SF-1 and LRH-1, and may play a role in estrogen-mediated ovarian folliculogenesis.

The bile acid synthesis pathway is present and functional in the human ovary

BACKGROUND

Bile acids, end products of the pathway for cholesterol elimination, are required for dietary lipid and fat-soluble vitamin absorption and maintain the balance between cholesterol synthesis in the liver and cholesterol excretion. They are composed of a steroid structure and are primarily made in the liver by the oxidation of cholesterol. Cholesterol is also highly abundant in the human ovarian follicle, where it is used in the formation of the sex steroids.

METHODOLOGY/PRINCIPAL FINDINGS

Here we describe for the first time evidence that all aspects of the bile acid synthesis pathway are present in the human ovarian follicle, including the enzymes in both the classical and alternative pathways, the nuclear receptors known to regulate the pathway, and the end product bile acids. Furthermore, we provide functional evidence that bile acids are produced by the human follicular granulosa cells in response to cholesterol presence in the culture media.

CONCLUSIONS/SIGNIFICANCE

These findings establish a novel pathway present in the human ovarian follicle that has the capacity to compete directly with sex steroid synthesis.

The metastasis-associated genes MTA1 and MTA3 are abundantly expressed in human placenta and chorionic carcinoma cells

Normal placenta development relies on the ability of trophoblast cells to invade into the uterus and to build up an extensively vascularized feto-maternal tissue, necessary for the nutrition of the embryo. The ability of cell migration, invasion, and the ability to induce neovascularization are likewise hallmarks of cancer cells. The metastasis-associated genes MTA1 and MTA3 are known to be involved in cancer cell migration by regulation of cell adhesion proteins and to induce the expression of neoangiogenic cytokines, as recently shown by us for ovarian cancer cells. Therefore, we analyzed the expression of MTA1 and MTA3 in normal human placenta tissues and the chorionic cancer cell lines BeWo, JEG, and JAR. Immunohistochemical analysis revealed a rather strong expression of MTA1 and MTA3 in the nuclei of human trophoblast cells. A high expression level of MTA1 and MTA3 was further observed in the nuclei of human chorionic carcinoma cells, as shown by immunofluorescence analysis, and confirmed by Western blot and RT-PCR analysis. We conclude that the high expression level of MTA proteins in human chorionic cells might facilitate trophoblast cell migration and neoangiogenesis, and might further predispose human chorionic cancer cells with properties that are characteristic for this highly aggressive and metastatic carcinoma type.

Neuroprotective actions of brain aromatase

The steroidal regulation of vertebrate neuroanatomy and neurophysiology includes a seemingly unending list of brain areas, cellular structures and behaviors modulated by these hormones. Estrogens, in particular have emerged as potent neuromodulators, exerting a range of effects including neuroprotection and perhaps neural repair. In songbirds and mammals, the brain itself appears to be the site of injury-induced estrogen synthesis via the rapid transcription and translation of aromatase (estrogen synthase) in astroglia. This induction seems to occur regardless of the nature and location of primary brain damage. The induced expression of aromatase apparently elevates local estrogen levels enough to interfere with apoptotic pathways, thereby decreasing secondary degeneration and ultimately lessening the extent of damage. There is even evidence suggesting that aromatization may affect injury-induced cytogenesis. Thus, aromatization in the brain appears to confer neuroprotection by an array of mechanisms that involve the deceleration and acceleration of degeneration and repair, respectively. We are only beginning to understand the factors responsible for the injury-induced transcription of aromatase in astroglia. In contrast, much of the manner in which local and circulating estrogens may achieve their neuroprotective effects has been elucidated. However, gaps in our knowledge include issues about the cell-specific regulation of aromatase expression, steroidal influences of aromatization distinct from estrogen formation, and questions about the role of constitutive aromatase in neuroprotection. Here we describe the considerable consensus and some interesting differences in knowledge gained from studies conducted on diverse animal models, experimental paradigms and preparations towards understanding the neuroprotective actions of brain aromatase.

Elevated aromatase expression correlates with cervical carcinoma progression

OBJECTIVES

We have previously demonstrated that aromatase mRNA is induced in cervical carcinomas compared to normal tissue, suggesting that in situ aromatase expression leading to elevated local estrogen production may contribute to cervical carcinogensis. Our objectives are to examine 1) whether aromatase protein and activity are induced in cervical carcinomas, 2) aromatase expression correlates with disease stage, and 3) inflammatory cytokines (e.g., IL-6 and TNFalpha) may correlate with aromatase expression.

METHODS

RNA and protein were isolated from human cervical carcinomas and normal cervical biopsies to examine aromatase expression, using real-time RT-PCR, Western blot analysis, and immunohistochemistry. Aromatase activity in tissue was measured using the tritiated water release method. IL-6 and TNFalpha expression was also examined.

RESULTS

Aromatase protein and activity levels were increased in cervical carcinomas compared to normal tissue. RNA levels correlated significantly with disease progression, with highest aromatase expression detected in stage IV tumors (p<0.001, R(2)=0.77). Aromatase promoters 1.3 and 1.4 were elevated in cervical carcinomas and in cervical cancer cells. The expression of inflammatory cytokines IL-6 and TNFalpha, known to induce aromatase, significantly correlated with aromatase expression (R(2)>0.9). TNFalpha treatment induced aromatase expression in cervical cancer cells.

CONCLUSION

Increased aromatase protein and activity in cervical carcinomas and the correlation of its expression with disease stage implicates it in cervical carcinogenesis. The correlation of IL-6 and TNFalpha expression with aromatase suggests that these inflammatory cytokines may induce aromatase expression, which is confirmed by induction of aromatase expression due to TNFalpha treatment of cervical cancer cells.

Mutations in NR5A1 associated with ovarian insufficiency

BACKGROUND

The genetic causes of nonsyndromic ovarian insufficiency are largely unknown. A nuclear receptor, NR5A1 (also called steroidogenic factor 1), is a key transcriptional regulator of genes involved in the hypothalamic-pituitary-steroidogenic axis. Mutation of NR5A1 causes 46,XY disorders of sex development, with or without adrenal failure, but growing experimental evidence from studies in mice suggests a key role for this factor in ovarian development and function as well.

METHODS

To test the hypothesis that mutations in NR5A1 cause disorders of ovarian development and function, we sequenced NR5A1 in four families with histories of both 46,XY disorders of sex development and 46,XX primary ovarian insufficiency and in 25 subjects with sporadic ovarian insufficiency. None of the affected subjects had clinical signs of adrenal insufficiency.

RESULTS

Members of each of the four families and 2 of the 25 subjects with isolated ovarian insufficiency carried mutations in the NR5A1 gene. In-frame deletions and frameshift and missense mutations were detected. Functional studies indicated that these mutations substantially impaired NR5A1 transactivational activity. Mutations were associated with a range of ovarian anomalies, including 46,XX gonadal dysgenesis and 46,XX primary ovarian insufficiency. We did not observe these mutations in more than 700 control alleles.

CONCLUSIONS

NR5A1 mutations are associated with 46,XX primary ovarian insufficiency and 46,XY disorders of sex development.

Liver receptor homolog 1 is essential for ovulation

Female fertility requires normal ovarian follicular growth and ovulation. The nuclear receptor liver receptor homolog 1 has been implicated in processes as diverse as bile acid metabolism, steroidogenesis, and cell proliferation. In the ovary, Lrh1 is expressed exclusively in granulosa and luteal cells. Using somatic targeted mutagenesis, we show that mice lacking Lrh1 in granulosa cells are sterile, due to anovulation. The preovulatory stimulus fails to elicit cumulus expansion, luteinization, and follicular rupture in these mice. Multiple defects, including severely reduced transactivation of the Lrh1 target gene, nitric oxide synthase 3, leads to increased intrafollicular estradiol levels in the absence of Lrh1. This further causes dysfunction of prostaglandin and hyaluronic acid cascades and interrupts cumulus expansion. Lack of Lrh1 also interferes with progesterone synthesis because of failure of normal expression of the Lrh1 targets, steroidogenic acute regulatory protein and cytochrome P450 side-chain cleavage. In addition, expression of extracellular matrix proteases essential for ovulation is compromised. These results demonstrate that Lrh1 is a regulator of multiple mechanisms essential for maturation of ovarian follicles and for ovulation. Lrh1 is therefore a key modulator of female fertility and a potential target for contraception.

Conditional deletion of the retinoblastoma (Rb) gene in ovarian granulosa cells leads to premature ovarian failure

The retinoblastoma protein (RB) regulates cell proliferation and survival by binding to the E2F family of transcription factors. Recent studies suggest that RB also regulates differentiation in a variety of cell types, including myocytes, neurons, adipocytes, and chondrocytes. Rb mutations have been found in ovarian cancer; however, the role of RB in normal and abnormal ovarian function remains unclear. To test the hypothesis that loss of Rb induces ovarian tumorigenesis, we generated an ovarian granulosa cell conditional knockout of Rb (Rb cKO) using the Cre/lox recombination system. Rb cKO females showed 100% survival and no ovarian tumor formation through 9 months of age, but they developed progressive infertility. Prepubertal Rb cKO females showed increased ovulation rates compared with controls, correlating with increased follicle recruitment, higher Fshr and Kitl mRNA levels, and lower anti-Müllerian hormone levels. In contrast, the ovulation rate of 6-wk-old females was similar to that of controls. Morphometric analysis of Rb cKO ovaries from 6-wk-old and older females showed increased follicular atresia and apoptosis. Rb cKO ovaries and preantral follicles had abnormal levels of known direct and indirect target genes of RB, including Rbl2/p130, E2f1, Ccne2, Myc, Fos, and Tgfb2. In addition, preantral follicles showed increased expression of the granulosa cell differentiation marker Inha, decreased levels of Foxl2 and Cyp19a1 aromatase, and abnormal expression of the nuclear receptors Nr5a1, Nr5a2, and Nr0b1. Taken together, our results suggest that RB is required for the temporal-specific pattern of expression of key genes involved in follicular development.