Granulosa Cell Aromatase Research Articles

The relationship between CYP19A1 gene expression in luteinized granulosa cells and follicular estradiol output in women with endometriosis

Endometriosis was claimed to negatively affect the intrafollicular environment, hindering oocyte competence. Previous studies evaluated expression levels of cytochrome P450 aromatase (CYP19A) in granulosa and cumulus oophorus cells collected from endometriosis women, but results are controversial. To further investigate the intrafollicular environment whose alteration may potentially disturb ovarian steroidogenesis in endometriosis, gene expression of CYP19A and of its upstream enzymes, StAR and 3βHSD was assessed in luteinized granulosa cells isolated from follicular fluids (FF) collected during Assisted Reproduction Technology (ART) procedures in women with stage III-IV disease and from subjects without the condition. In a subgroup of patients, cumulus oophorus cells (COCs) were also assessed for CYP19A, StAR and 3βHSD gene expression. No difference in mRNA expression of CYP19A1, StAR and 3βHSD in both granulosa cells and COCs was observed between the two groups of patients. No significant difference was also found between estradiol FF levels detected in endometriosis patients (median=873, IQR=522–1221 ng/ml)) and control patients (median=878, IQR=609–1137 ng/ml). To gain more insight into the intrafollicular regulation of CYP19A in patients with endometriosis, associations between expression of the analyzed genes, systemic and follicular 17β-estradiol levels and ART outcomes were assessed. While in the control group, levels of CYP19A1, StAR and 3βHSD transcripts significantly correlated with follicular estradiol levels (adjusted R² of 0.60), no significant association was detected in affected women (adjusted R² of 0.23). After stratification of the populations based on the presence of the disease, CYP19A1 expression was shown to correlate with the number of oocytes retrieved [β:− 1.214;95%CI: − 2.085 - (−0.343); p = 0.007] in the control group while this association was not present in patients with endometriosis [β:− 0.003; 95%CI:− 0.468–0.461; p = 0.988)]. These results do not support data from the literature indicating a reduced aromatase expression in granulosa cells of affected women, but they highlight a potential subtle mechanism affecting the ovulation process in these women.

Downregulation of the Expression of Steroidogenic Acute Regulatory Protein and Aromatase in Steroidogenic KGN Human Granulosa Cells after Exposure to Bisphenol A.

Although increasing evidence of cause-and-effect relationship between BPA exposure and female reproductive disorders have been suggested through many studies, the precise biochemical and molecular mechanism(s) by which BPA interferes with steroidogenesis in the ovarian cells still remain unclear. Therefore, the purpose of this study was to discover the steroidogenic biomarker(s) associated with BPA treatment in human granulosa cell line, KGN. In this study, our results obtained via the analysis of steroidogenesis-related protein expression in KGN cells using quantitative polymerase chain reaction (qPCR) and western blot analyses revealed that the expression levels of steroidogenic acute regulatory (StAR) and aromatase decreased considerably and gradually after BPA treatment in a dose-dependent manner under BPA treatment. Further, remarkable decreases in their expression levels at the cellular levels were also confirmed via immunocytochemistry, and subsequent StAR and aromatase mRNA expression levels showed profiles similar to those observed for their proteins, i.e., both StAR and aromatase mRNA expression levels were significantly decreased under BPA treatment at concentrations ≥0.1 μM. We observed that follicle stimulating hormone upregulated StAR and aromatase protein expression levels; however, this effect was suppressed in the presence of BPA. Regarding the steroidogenic effects of BPA on KGN cells, controversies remain regarding the ultimate outcomes. Nevertheless, we believe that the results here presented imply that KGN cells have a good cellular and steroidogenic machinery for evaluating endocrine disruption. Therefore, StAR and aromatase could be stable and sensitive biomarkers in KGN cells for the cellular screening of the potential risk posed by exogenous and environmental chemicals to female reproductive (endocrine) function.

Myo-Inositol and D-Chiro-Inositol as Modulators of Ovary Steroidogenesis: A Narrative Review.

Myo-inositol is a natural polyol, the most abundant among the nine possible structural isomers available in living organisms. Inositol confers some distinctive traits that allow for a striking distinction between prokaryotes and eukaryotes, the basic clusters into which organisms are partitioned. Inositol cooperates in numerous biological functions where the polyol participates or by furnishing the fundamental backbone of several related derived metabolites, mostly obtained through the sequential addition of phosphate groups (inositol phosphates, phosphoinositides, and pyrophosphates). Overall myo-inositol and its phosphate metabolites display an entangled network, which is involved in the core of the biochemical processes governing critical transitions inside cells. Noticeably, experimental data have shown that myo-inositol and its most relevant epimer D-chiro-inositol are both necessary to permit a faithful transduction of insulin and of other molecular factors. This improves the complete breakdown of glucose through the citric acid cycle, especially in glucose-greedy tissues, such as the ovary. In particular, while D-chiro-inositol promotes androgen synthesis in the theca layer and down-regulates aromatase and estrogen expression in granulosa cells, myo-inositol strengthens aromatase and FSH receptor expression. Inositol effects on glucose metabolism and steroid hormone synthesis represent an intriguing area of investigation, as recent results have demonstrated that inositol-related metabolites dramatically modulate the expression of several genes. Conversely, treatments including myo-inositol and its isomers have proven to be effective in the management and symptomatic relief of a number of diseases associated with the endocrine function of the ovary, namely polycystic ovarian syndrome.

Effects of lipopolysaccharide on beta-catenin, aromatase, and estrogen production in bovine granulosa cells in vivo and in vitro

Diseases resulting from Gram-negative bacterial infection can induce an immune response by releasing a lipopolysaccharide (LPS) endotoxin that may lead to impaired fertility in cows. To evaluate the effects of LPS on follicular dynamics in a subacute inflammatory disease state, 14 Angus heifers (BW = 413 kg±14) were blocked by weight and assigned to vehicle (n = 7) or LPS treated (n = 7) groups. Heifers received subcutaneous injections of saline (CON) or 2.0 μg/kg LPS on d 2, 5, and 8 of a select synch plus controlled internal drug release device (CIDR) follicular wave synchronization protocol. Fifty hours following CIDR withdrawal, ovaries were harvested, and follicular fluid was collected for hormone and LPS analysis. Daily blood samples were collected from d 0 to d 7. Beginning on d 8 blood samples were collected at 0, 16, 24, 32, 40, and 50 h following LPS challenge. Rectal temperatures were recorded prior to treatment and at regular intervals after each LPS challenge. Heifers treated with LPS exhibited mild (+0.5 °C) hyperthermia (P < 0.05) at 3, 4, and 8 h after the initial LPS challenge (d 2) when compared to vehicle-treated controls. Follicular fluid concentrations of estradiol (E2) increased (P = 0.04) in LPS-treated heifers compared to controls (1,595 ng/mL and 808 ng/mL±240, respectively), while follicular fluid progesterone (P4) concentrations did not differ (P = 0.27) between treatment groups. Additionally, LPS concentrations tended to be increased (P = 0.59) in dominant follicles of LPS-treated heifers, but no difference was detected (P = 0.81) in small developing follicles. To further delineate the impact of LPS on ovarian signaling pathways, a granulosa cell line (KGN) was incubated in the presence or absence of LPS (10 μg/mL) for 48 h. Cells were then collected for gene expression and protein analysis. Cells in both treatment groups expressed toll-like receptor 4, myeloid differentiation factor-2 receptor, and CD-14 complex genes required for LPS signaling. Cells treated with LPS exhibited decreased mRNA expression of aromatase (P = 0.03) and beta-catenin (P = 0.02). However, no change (P > 0.10) was detected in abundance of total beta-catenin protein or beta-catenin phosphorylated isoforms at serine 552 or 675. Based on results from this in vivo experiment, these investigators concluded that low doses of LPS can alter E2 concentrations and this effect may be modulated in part through beta-catenin regulation of aromatase transcription.

Estrogen disorders: Interpreting the abnormal regulation of aromatase in granulosa cells (Review).

Ovarian granulosa cells (GCs) are the most important source of estrogen. Therefore, aromatase (estrogen synthase), which is the key enzyme in estrogen synthesis, is not only an important factor of ovarian development, but also the key to estrogen secretion by GCs. Disorders of the ovarian estrogen secretion are more likely to induce female estrogen-dependent diseases and fertility issues, such as ovarian cancer and polycystic ovary syndrome. Hence, aromatase is an important drug target; treatment with its inhibitors in estrogen-dependent diseases has attracted increasing attention. The present review article focuses on the regulation and mechanism of the aromatase activity in the GCs, as well as the specific regulation of aromatase promoters. In GCs, follicle-stimulating hormone (FSH) is dependent on the cyclic adenosine monophosphate (cAMP) pathway to regulate the aromatase activity, and the regulation of this enzyme is related to the activation of signaling pathways, such as phosphatidylinositol 3-kinase (PI3K) and extracellular signal-regulated kinase (ERK). In addition, endocrine-disrupting substance and other related factors affect the expression of aromatase, which eventually create an imbalance in the estrogen secretion by the target tissues. The present review highlights these useful factors as potential inhibitors for target therapy.

Altered Deoxyribonucleic Acid Methylation Underlies the Aberrant Expression of Androgen Synthesis Related Genes in Polycystic Ovary Syndrome

To determine the correlation between deoxyribonucleic acid methylation and gene expression of cytochrome P450 family 19 subfamily A polypeptide 1 cytochrome P450 family 19 subfamily a member 1, anti-Mullerian hormone and anti-Mullerian hormone receptor type 2, which regulate follicle development and androgen metabolism in polycystic ovary syndrome pathogenesis. The levels of cytochrome P450 family 19 subfamily a member 1, anti-Mullerian hormone and anti-Mullerian hormone receptor type 2 messenger ribonucleic acid and protein expression were evaluated by various techniques in polycystic ovary syndrome patients. Estradiol, androstenedione and anti-Mullerian hormone levels were also tested in follicular fluid. In order to quantify the connection between deoxyribonucleic acid methylation and gene expression, we conducted Pearson product-moment correlation coefficient analyses. The estradiol level did not alter, however the androstenedione level was increased. Polycystic ovary syndrome granulosa cells were hypermethylated cytochrome P450 family 19 subfamily a member 1, but hypomethylated anti- Mullerian hormone and anti-Mullerian hormone receptor type 2. In general, the greater the amount of deoxyribonucleic acid methylation, the lower the level of downstream messenger ribonucleic acid and protein expression. Aromatase enzyme activity is regulated by deoxyribonucleic acid methylation and a hormone called follicular estradiol/androstenedione ratio is linked with it. A prior study reported that anti- Mullerian hormone inhibits aromatase in granulosa cells and therefore the inverse connection between cytochrome P450 family 19 subfamily a member 1 and anti-Mullerian hormone confirms that finding. Our study suggests alterations in deoxyribonucleic acid methylation as the underlying mechanism of aberrant gene expression of cytochrome P450 family 19 subfamily a member 1, anti-Mullerian hormone and anti- Mullerian hormone receptor type 2 and polycystic ovary syndrome pathogenesis.

High ovarian GDF-8 levels contribute to elevated estradiol production in ovarian hyperstimulation syndrome by stimulating aromatase expression.

Rationale: Growth differentiation factor-8 (GDF-8), also known as myostatin, belongs to the transforming growth factor-beta (TGF-β) superfamily. GDF-8 is expressed in the ovary and regulates various ovarian functions. Ovarian hyperstimulation syndrome (OHSS) is one of the most serious disorders during in vitro fertilization treatment. Aromatase, encoded by the CYP19A1 gene, is the enzyme that catalyzes the final step in estradiol (E2) biosynthesis. It has been demonstrated that high serum E2 levels are associated with the development of OHSS. However, the effects of GDF-8 on aromatase expression and its roles in the pathogenesis of OHSS remain unclear.Methods: The effect of GDF-8 on aromatase expression and the underlying mechanisms were explored by a series of in vitro experiments in primary human granulosa-lutein (hGL) and KGN cells. Rat OHSS model and human follicular fluid samples were used to examine the roles of the GDF-8 system in the pathogenesis of OHSS.Results: We demonstrate that GDF-8 stimulates aromatase expression and E2 production in hGL and KGN cells. In addition, TGF-β type I receptor ALK5-mediated SMAD2/3 signaling is required for GDF-8-induced aromatase expression and E2 production. Using a rat OHSS model, we show that the aromatase and GDF-8 levels are upregulated in the ovaries of OHSS rats. Blocking the function of ALK5 by the administration of its inhibitor, SB431542, alleviates OHSS symptoms and the upregulation of aromatase. Clinical results reveal that the protein levels of GDF-8 are upregulated in the follicular fluid of OHSS patients. Moreover, the expression of GDF-8 is increased in hGL cells of OHSS patients.Conclusions: This study helps to elucidate the mechanisms mediating the expression of aromatase in human granulosa cells, which may lead to the development of alternative therapeutic approaches for OHSS.

Progesterone dose during synchronization treatment alters luteinizing hormone receptor and steroidogenic enzyme mRNA abundances in granulosa cells of Nellore heifers

The objective was to investigate effects of progesterone (P4) dose on abundance of luteinizing hormone receptor (LHCGR), aromatase (CYP19A1), 3β-hydroxysteroid dehydrogenase (HSD3B1), and other steroidogenic mRNA transcripts in granulosa cells from dominant follicles. Nellore heifers were assigned to one of six groups: new, first-use controlled internal drug release device (CIDR1) inserted for 5 days (Large-P4-dose-D5; n = 7) or 6 days (Large-P4-dose-D6; n = 8), prostaglandin (PG)F2α administered on D0 and 1 previously-used CIDR (CIDR3) inserted for 5 days (Small- P4-dose-D5; n = 8) or 6 days (Small-P4-dose-D6; n = 8), CIDR1 inserted on D0 and removed plus PGF2α on D5 (Large-P4-dose-proestrus (PE); n = 7), and CIDR3 and PGF2α on D0 and 1, CIDR3 removed plus PGF2α on D5 (Small-P4-dose-PE; n = 7). Duration of P4 treatment (D5 compared to D6) affected abundances of CYP19A1 mRNA transcripts, with there being greater abundances on D6 than D5 (P ≤ 0.05). Heifers treated with the large dose of P4 had a smaller dominant follicle, less serum and intra-follicular estradiol (E2) concentrations (P ≤ 0.05) and lesser LHCGR, CYP19A1, and HSD3B1 transcript abundances (P ≤ 0.05). Heifers treated to induce PE had a larger follicle diameter (P = 0.09), greater intra-follicular E2 concentrations and larger abundances of CYP19A1 mRNA transcript (P ≤ 0.05) than heifers of the D6 group. Overall, treatment with larger doses of P4 resulted in lesser abundances of LHCGR, HSD3B1, and CYP19A1 mRNA transcripts; thus, potentially leading to development of smaller dominant follicles and lesser E2 concentrations.

Sam68 mediates leptin signaling and action in human granulosa cells: possible role in leptin resistance in PCOS.

IntroductionPolycystic ovary syndrome (PCOS) is a complex metabolic disorder associated with ovulatory dysfunction, hyperandrogenism, obesity, and insulin resistance, that leads to subfertility. Sam68 is an RNA-binding protein with signaling functions that is ubiquitously expressed, including gonads. Sam68 is recruited to leptin signaling, mediating different leptin actions.ObjectiveWe aimed to investigate the role of Sam68 in leptin signaling, mediating the effect on aromatase expression in granulosa cells and the posible implication of Sam68 in the leptin resistance in PCOS.Materials and methodsGranulosa cells were from healthy donors (n = 25) and women with PCOS (n = 25), within the age range of 20 to 40 years, from Valencian Infertility Institute (IVI), Seville, Spain. Sam68 expression was inhibited by siRNA method and overexpressed by expression vector. Expression level was analysed by qPCR and immunoblot. Statistical significance was assessed by ANOVA followed by different post-hoc tests. A P value of <0.05 was considered statistically significant.ResultsWe have found that leptin stimulation increases phosphorylation and expression level of Sam68 and aromatase in granulosa cells from normal donors. Downregulation of Sam68 expression resulted in a lower activation of MAPK and PI3K pathways in response to leptin, whereas overexpression of Sam68 increased leptin stimulation of signaling, enhancing aromatase expression. Granulosa cells from women with PCOS presented lower expression of Sam68 and were resistant to the leptin effect on aromatase expression.ConclusionsThese results suggest the participation of Sam68 in leptin receptor signaling, mediating the leptin effect on aromatase expression in granulosa cells, and point to a new target in leptin resistance in PCOS.

A putative protein-RNA complex regulates posttranscriptional processing of cytochrome P450 aromatase (CYP19A1) in bovine granulosa cells.

Follicle growth and granulosa cell health are dependent on the secretion of estradiol from granulosa cells. Estradiol is synthesized from androgen precursor by cytochrome P450 aromatase (CYP19A1), and in cattle CYP19A1 messenger RNA has a short half-life but a long (3.5 kb) 3'-untranslated region (3'UTR), suggesting that posttranscriptional regulation may be important for control of enzyme activity. We tested this hypothesis by inserting the CYP19A1 3'UTR and fragments thereof into a reporter vector between the end of the luciferase coding region and the polyadenylation signal. The full-length aromatase 3'UTR suppressed luciferase activity to 10% of control levels, and smaller fragments showed that this inhibitory activity lies between +926 and +1134 of the 3'UTR. Protein-RNA cross-linking experiments revealed that these 3'UTR fragments formed an RNA-protein complex of approximately 70 kDa that was present in granulosa cells but not in corpus luteum, lung, liver, kidney, pancreas, or bladder extracts. The RNA-binding activity was specific to the 3'UTR, as shown by competition experiments with unlabeled RNA, and was present only in 3'UTR constructs that inhibited luciferase activity. These data suggest that posttranscriptional regulation is an important component of the control of CYP19A1 expression and involves protein binding to a specific sequence in the 3'UTR.

MON-202 Changes in the Expression of Epigenetic Enzymes Induced by Prenatal Testosterone Excess May Underlie the Antral Follicular Defects in the Sheep Model of PCOS

Prenatal testosterone (T) excess leads to oligo/anovulation and multifollicular ovary in sheep, characteristics of women with PCOS. Persistence of antral follicles - the result of reduced atresia, follicular growth arrest and premature luteinization, contribute at least in part to the multifollicular ovarian morphology. Decrease in aromatase (CYP19) in granulosa cells and 17alpha-hydroxylase (CYP17) in theca cells and increase in anti-Mullerian hormone (AMH) in granulosa cells may contribute to the antral follicular persistence. Observations that histone H3K9 hypermethylation decreases cumulus cell CYP19 (Journal of Assisted Reproduction and Genetics 33: 1105-1113, 2016), AMH gene hypermethylation reduces granulosa cell AMH (Oncotarget 6: 3627-3643, 2015), and inhibition of histone deacetylation reduces theca cell CYP17 expression (PloS One 7: e49553, 2012) suggest that epigenetic changes are involved. We hypothesized that prenatal T excess induced changes in expression of CYP17, CYP19 and AMH are facilitated by changes in expression of key epigenetic enzymes. Granulosa / theca cells were isolated via laser capture microdissection from antral follicles of 21 months-of-age control (n=5) and prenatal T-treated (100mg im. twice weekly from gestational day 30 to 90; term: 147 days; n=6) sheep. Expression of methylation / demethylation and / or acetylation / deacetylation enzymes were determined by real time PCR and data analyzed by Student’s t-test and Cohen’s effect size analysis. Prenatal T excess decreased (p < 0.05) histone demethylase KDM1A in granulosa and theca cells, histone acetylase (HDAC) 3 in theca cells, and increased histone methyltransferase SMYD3 in the theca cells. Prenatal T excess also induced large magnitude (1) increases in DNA methyltransferase (DNMT) 1, histone methyltransferases EZH2 and SUV39H1, and histone deacetylase HDAC1 in granulosa cells; (2) decrease in DNA methyltransferase DNMT3B, KDM1A, and HDAC3 in granulosa cells; (3) increase in SMYD3 and HDAC1 in theca cells, and (4) decrease in KDM1A and HDAC3 in theca cells. While decrease in KDM1A and increase in SUV39H1 leading to H3K9 hypermethylation may account for reduced granulosa cell expression of CYP19, downregulation of HDAC3 may underlie the decrease in thecal cell expression of CYP17. Decreased DNMT3B expression may contribute to hypomethylation of AMH gene and consequent increase in AMH expression in granulosa cells. These findings suggest that changes in expression of key genes involved in the development of multifollicular phenotype are likely mediated via granulosa and theca cell specific changes in epigenetic enzyme expression. Because the ovarian attributes of prenatal T-treated sheep parallel that seen in PCOS women, these observations may be of translational relevance. Supported by NIH PO1HD44232.

The roles of the ovarian extracellular matrix in fertility

In the mammalian ovary there is considerable and continuous remodelling of tissue during both fetal and adult life, necessitating changes in extracellular matrix. Matrix is a diverse group of molecules varying in its composition and roles, which include regulation of growth factor activity and cell behaviour. Here we discuss four topical aspects of matrices in ovaries. (1) Our current state of knowledge of latent TGFß binding proteins that can bind the extracellular matrix fibrillins. Fibrillins and latent TGFß binding proteins may be very important given the genetic linkage data implicating a role for fibrillin 3 in polycystic ovarian syndrome. They will almost certainly be important in the stromal compartments of the ovary by regulating TGFß bioactivity. (2) Follicles which have an unusual ultrastructural follicular basal lamina and poor quality oocytes. The results suggest that the use of oocytes from these follicles should be avoided in assisted reproductive technologies. (3) Evidence that expression of components of focimatrix correlates with expression of aromatase and cholesterol side-chain cleavage in granulosa cells. Focimatrix is a novel type of basal lamina associated with granulosa cells with expression beginning before deviation and continuing until ovulation. It may be involved in maturation of granulosa cells and selection of the dominant follicle. (4) Evidence is presented in support of a hypothesis that follicular fluid accumulates in follicles due to the osmotic potential of hyaluronan and versican, which are matrices produced by granulosa cells and too large to traverse the follicular antrum. These examples illustrate the diversity of matrix and foreshadow potential important discoveries involving extracellular matrix in ovaries.

Clinical Case Seminar: Postmenopausal androgen excess-challenges in diagnostic work-up and management of ovarian thecosis.

Postmenopausal hyperandrogenism can be tumour- or non-tumour-related, with pathology residing either in the ovary or adrenal gland(s). The tempo of investigation is determined by the clinical severity of hyperandrogenism (presence/absence of actual virilisation) and degree of serum testosterone elevation. When clinical or biochemical hyperandrogenism is severe, rapidly developing, or associated with hypercortisolism, screening for adrenocortical or ovarian carcinoma with cross-sectional imaging should be prioritised over detailed biochemical evaluation. Adrenal hyperandrogenism is readily characterised, both biochemically and radiologically. By contrast, even a combination of high-resolution imaging with laboratory evaluation, including dynamic endocrine testing, often cannot distinguish between ovarian hyperthecosis (OH) and virilising ovarian tumour (VOT); a definitive diagnosis usually emerging only after histological examination of excised ovaries. VOTs are typically below the resolution-limit of current imaging modalities and exhibit suppression of gonadotropin-dependent androgen secretion with GnRH-analogue therapy. Thus, for well-characterised ovarian hyperandrogenism, laparoscopic bilateral salpingo-oophorectomy may serve both as a diagnostic and therapeutic procedure. Nevertheless, women unable or unwilling to undergo ovarian surgery can be reassured that malignant VOTs are exceedingly rare and that long-term medical therapy with oral antiandrogens or GnRH-analogues is safe and well-tolerated. OH is strongly associated with insulin-resistance, with hyperinsulinaemia acting synergistically with raised gonadotropin levels to stimulate thecal cell hyperplasia and androgen secretion by the postmenopausal ovary, which lacks granulosa cell aromatase activity and thus cannot convert testosterone to 17 beta estradiol. Thus, features of metabolic syndrome may indicate OH, and significant reductions in androgens can thereby potentially be achieved with lifestyle measures and/or insulin-sensitising drugs.

Local effect of bisphenol A on the estradiol synthesis of ovarian granulosa cells from PCOS

Close relationship between polycystic ovary syndrome (PCOS) and bisphenol A (BPA) has drawn much attention in recent years, while the underlying mechanisms are poorly understood. In our study, we aim to detect BPA concentration in the follicular fluid and investigate its effect on estradiol synthesis in human granulosa cells from PCOS and non-PCOS patients. Follicular fluid and granulosa cells were collected from women who underwent controlled ovarian stimulation for in vitro fertilization or intracytoplasmic sperm injection. BPA concentration in the follicular fluid from PCOS patients (440.50 ± 63.70 pg/ml) was significantly higher than that from non-PCOS patients (338.00 ± 57.88 pg/ml). Expression of aromatase and estradiol synthesis in cultured granulosa cells was examined after treatment with BPA from 0.01 to 1 μM for 24 h. Expression of aromatase and estradiol synthesis was downregulated by BPA in a dose-dependent manner in PCOS, but no effect was observed in granulosa cells from non-PCOS patients. These findings provide evidence that increased BPA concentration in the follicular fluid of PCOS patients may play an important role in its pathogenesis by attenuating the expression of aromatase in granulosa cells.

Rosiglitazone suppresses FSH and IGF-1 induced downstream PI3K/Akt pathway mediated granulosa cell function involving PPARg and PTEN: Potential targets of fertility regulation

Nuclear receptor peroxisome proliferative activated receptor gamma (PPARg) is a prominent targeted molecule in ovarian syndrome. Rosiglitazone, a potent drug administered during Polycystic ovarian syndrome (PCOS), executes its effects through this receptor. However, the exact mechanism through which Rosiglitazone induces PPARg and mediates its action in ovary is not well documented. In the present study, we delineated the signaling pathway for Rosiglitazone action in granulosa cell functioning by using buffalo granulosa cell model. Experiments were performed in serum free primary buffalo granulosa cell culture when cells were follicle stimulating hormone (FSH) responsive with pre-ovulatory phenotype. The cells were incubated with Rosiglitazone alone or in combination with FSH (25 ng/ml) and IGF-1(50 ng/ml). Results showed that Rosiglitazone (25 µM) inhibited FSH and insulin like growth factor-1 (IGF-1) induced granulosa cell proliferation, aromatase, GATA-4, IGF-1 mRNA and oestradiol-17β production. Western blot analysis of total cell lysates revealed that Rosiglitazone intervene with the FSH and IGF-1 signaling by decreasing p-Akt. In addition, Rosiglitazone was found to up-regulate PPAR g and (PTEN) in granulosa cells. PPARg antagonist (GW9662) had no effect on p-Akt level, as well as on steroidogenesis. PTEN inhibitor bpV(pic) revived Akt phosphorylation to the level of control. In conclusion, the present study demonstrated that Rosiglitazone attenuated FSH and IGF-1 induced downstream PI3K/Akt pathway mediated granulosa cell function ( proliferation and steroidogenesis) involving PPARg and PTEN . The elucidated signaling pathway and participating molecules, PPARg and PTEN, could be potential targets while developing novel molecules in PCOS management and fertility regulation

Two natural products, trans-phytol and (22E)-ergosta-6,9,22-triene-3β,5α,8α-triol, inhibit the biosynthesis of estrogen in human ovarian granulosa cells by aromatase (CYP19)

Aromatase is the only enzyme in vertebrates to catalyze the biosynthesis of estrogens. Although inhibitors of aromatase have been developed for the treatment of estrogen-dependent breast cancer, the whole-body inhibition of aromatase causes severe adverse effects. Thus, tissue-selective aromatase inhibitors are important for the treatment of estrogen-dependent cancers. In this study, 63 natural products with diverse structures were examined for their effects on estrogen biosynthesis in human ovarian granulosa-like KGN cells. Two compounds—trans-phytol (SA-20) and (22E)-ergosta-6,9,22-triene-3β,5α,8α-triol (SA-48)—were found to potently inhibit estrogen biosynthesis (IC50: 1μM and 0.5μM, respectively). Both compounds decreased aromatase mRNA and protein expression levels in KGN cells, but had no effect on the aromatase catalytic activity in aromatase-overexpressing HEK293A cells and recombinant expressed aromatase. The two compounds decreased the expression of aromatase promoter I.3/II. Neither compound affected intracellular cyclic AMP (cAMP) levels, but they inhibited the phosphorylation or protein expression of cAMP response element-binding protein (CREB). The effects of these two compounds on extracellular regulated kinase (ERK), c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinases (MAPKs), and AKT/phosphoinositide 3-kinase (PI3K) pathway were examined. Inhibition of p38 MAPK could be the mechanism underpinning the actions of these compounds. Our results suggests that natural products structurally similar to SA-20 and SA-48 may be a new source of tissue-selective aromatase modulators, and that p38 MAPK is important in the basal control of aromatase in ovarian granulosa cells. SA-20 and SA-48 warrant further investigation as new pharmaceutical tools for the prevention and treatment of estrogen-dependent cancers.

Human Granulosa Cells: Insulin and Insulin-Like Growth Factor-1 Receptors and Aromatase Expression Modulation by Metformin

Background/Aim: Granulosa cells are the source of the most important ovarian steroids. Even in patients without significant improvement in metabolic parameters, metformin has apparently an important effect on the ovary. The aim of this study was to evaluate gene and protein expression of an insulin receptor (IR), insulin-like growth factor-1 (IGF1) receptor (IGF1R) and aromatase in granulosa cells treated with metformin and insulin. Methods: Luteinized granulosa cells were collected from 27 patients during in vitro fertilization procedures. Cells were isolated, stored in culture for 24 h and divided into four groups: control; metformin for 30 min, and metformin for 30 min plus insulin for 30 or 60 min. Results: IR and IGF1R mRNA expression was significantly enhanced by metformin but was not affected by insulin. Aromatase mRNA expression was significantly reduced in metformin-incubated cells following stimulation with insulin for 30 min. No statistical differences were found in IGF1R and aromatase protein expression, and IR expression was not detected. Conclusion: A direct effect of metformin on the gene expression of IGF1R, IR and aromatase was observed. Further studies should investigate the role of IGF1R, IR and aromatase in ovarian physiology for a better understanding of the effect of metformin.

Molecular mechanisms of luteinization

Dynamic changes in steroidogenesis occur in ovarian granulosa cells during ovulation after the LH surge. The ovulatory LH surge induces rapid up-regulation of steroidogenic acute regulatory (StAR) protein and rapid down-regulation of aromatase (Cyp19a1) in granulosa cells undergoing luteinization during ovulation. These rapid changes in StAR and Cyp19a1 gene expression after the LH surge efficiently facilitate progesterone production, which plays a crucial role in ovulation and the following luteinization. Recently, it has become clear that epigenetic regulation such as histone modifications and DNA methylation play a key role in gene expression through the chromatin remodeling of the promoter region. This study reports the in vivo evidence that epigenetic mechanisms including histone modifications, DNA methylation and chromatin remodeling are involved in the rapid changes of StAR and Cyp19a1 gene expression in granulosa cells undergoing luteinization during ovulation.

Evidence That Increased Ovarian Aromatase Activity and Expression Account for Higher Estradiol Levels in African American Compared With Caucasian Women

Serum estradiol levels are significantly higher across the menstrual cycle in African American (AAW) compared with Caucasian women (CW) in the presence of similar FSH levels, yet the mechanism underlying this disparity is unknown. The objective of the study was to determine whether higher estradiol levels in AAW are due to increased granulosa cell aromatase mRNA expression and activity. The design of the study included daily blood sampling and dominant follicle aspirations at an academic medical center during a natural menstrual cycle. Healthy, normal cycling AAW (n = 15) and CW (n = 14) aged 19-34 years participated in the study. Hormone levels in peripheral blood and follicular fluid (FF) aspirates and aromatase and FSH receptor mRNA expression in granulosa cells were measured. AAW had higher FF estradiol [1713.0 (1144.5-2032.5) vs 994.5 (647.3-1426.5) ng/mL; median (interquartile range); P < .001] and estrone [76.9 (36.6-173.4) vs 28.8 (22.5-42.1) ng/mL; P < .001] levels than CW, independent of follicle size. AAW also had lower FF androstenedione to estrone (7 ± 1.8 vs 15.8 ± 4.1; mean ± SE; P = .04) and T to estradiol (0.01 ± 0.002 vs 0.02 ± 0.005; P = .03) ratios, indicating enhanced ovarian aromatase activity. There was a 5-fold increase in granulosa cell aromatase mRNA expression in AAW compared with CW (P < .001) with no difference in expression of FSH receptor. FSH, inhibin A, inhibin B, and AMH levels were not different in AAW and CW. Increased ovarian aromatase mRNA expression, higher FF estradiol levels, and decreased FF androgen to estrogen ratios in AAW compared with CW provide compelling evidence that racial differences in ovarian aromatase activity contribute to higher levels of estradiol in AAW across the menstrual cycle. The absence of differences in FSH, FSH receptor expression, and AMH suggest that population-specific genetic variation in CYP19, the gene encoding aromatase, or in factors affecting its expression should be sought.

Changes in Histone Modification and DNA Methylation of the StAR and Cyp19a1 Promoter Regions in Granulosa Cells Undergoing Luteinization during Ovulation In Rats

The ovulatory LH surge induces rapid up-regulation of steroidogenic acute regulatory (StAR) protein and rapid down-regulation of aromatase (Cyp19a1) in granulosa cells (GCs) undergoing luteinization during ovulation. This study investigated in vivo whether epigenetic mechanisms including histone modifications are involved in the rapid changes of StAR and Cyp19a1 gene expression. GCs were obtained from rats treated with equine chorionic gonadotropin (CG) before (0 h) and after human (h)CG injection. StAR mRNA levels rapidly increased after hCG injection, reached a peak at 4 h, and then remained higher compared with 0 h until 12 h. Cyp19a1 mRNA levels gradually decreased after hCG injection and reached their lowest level at 12 h. A chromatin immunoprecipitation assay revealed that levels of histone-H4 acetylation (Ac-H4) and trimethylation of histone-H3 lysine-4 (H3K4me3) increased whereas H3K9me3 and H3K27me3 decreased in the StAR promoter after hCG injection. On the other hand, the levels of Ac-H3 and -H4 and H3K4me3 decreased, and H3K27me3 increased in the Cyp19a1 promoter after hCG injection. Chromatin condensation, which was analyzed using deoxyribonuclease I, decreased in the StAR promoter and increased in the Cyp19a1 promoter after hCG injection. A chromatin immunoprecipitation assay also showed that binding activities of CAATT/enhancer-binding protein β to the StAR promoter increased and binding activities of phosphorylated-cAMP response element binding protein to the Cyp19a1 promoter decreased after hCG injection. These results provide in vivo evidence that histone modifications are involved in the rapid changes of StAR and Cyp19a1 gene expression by altering chromatin structure of the promoters in GCs undergoing luteinization during ovulation.