Development of a human granulosa cell culture model with follicle stimulating hormone responsiveness

Synthetic human gonadal tissues for toxicology

The process of mammalian reproduction involves the development of fertile germ cells in the testis and ovary, supported by the surrounders. Fertilization leads to embryo development and ultimately the birth of offspring inheriting parental genome information. Any disruption in this process can result in disorders such as infertility and cancer. Chemical toxicity affecting the reproductive system and embryogenesis can impact birth rates, overall health, and fertility, highlighting the need for animal toxicity studies during drug development. However, the translation of animal data to human health remains challenging due to interspecies differences. In vitro culture systems offer a promising solution to bridge this gap, allowing the study of mammalian cells in an environment that mimics the physiology of the human body. Current advances on in vitro culture systems, such as organoids, enable the development of biomaterials that recapitulate the physiological state of reproductive organs. Application of these technologies to human gonadal cells would provide effective tools for drug screening and toxicity testing, and these models would be a powerful tool to study reproductive biology and pathology. This review focuses on the 2D/3D culture systems of human primary testicular and ovarian cells, highlighting the novel approaches for in vitro study of human reproductive toxicology, specifically in the context of testis and ovary.

Bone morphogenetic protein-9 downregulates StAR expression by inducing snail expression via SMAD1/5/8 signaling in human granulosa-lutein cells

Ovarian steroidogenesis mediated by granulosa cells is pivotal in maintaining normal female reproductive function. The steroidogenic acute regulatory protein (StAR) regulates the rate-limiting step in steroidogenesis. Bone morphogenetic protein-9 (BMP-9), also known as growth differentiation factor-2 (GDF-2), is a member of the transforming growth factor-beta (TGF-β) superfamily. BMP-9 induces epithelial-mesenchymal transition (EMT) that contributes to cancer progression. However, the function of BMP-9 in the female reproductive system remains largely unknown. It has been recently shown that BMP-9 is expressed in human follicular fluid and can downregulate StAR expression in human ovarian granulosa cells. However, the underlying molecular mechanisms warrant investigation. Our results show that treatment of primary granulosa-lutein (hGL) cells with BMP-9 downregulates StAR expression. In addition, two EMT-related transcription factors, Snail and Slug, are upregulated by the treatment of BMP-9. Using pharmacological inhibitors and a siRNA-mediated knockdown approach, we show that BMP-9 upregulates Snail and Slug expression by activating SMAD1/5/8 signaling. We also examine the effects of BMP-9 on SMAD-independent signaling pathways, including ERK1/2, p38, JNK, AKT, and CREB. However, none of them is affected by the BMP-9. Moreover, we use gain- and loss-of-function approaches to reveal that only Snail, not Slug, is required for the BMP-9-induced downregulation of StAR expression in hGL cells. This study increases the understanding of the physiology function of BMP-9 in hGL cells and provides important insights into the regulation of StAR expression.

TGF-β1 and TGF-β3, but not TGF-β2, are upregulated in the ovaries of ovarian hyperstimulation syndrome†

Ovarian hyperstimulation syndrome (OHSS) is a life-threatening and potentially fatal complication during in vitro fertilization treatment. The levels of transforming growth factor-β1 (TGF-β1) are upregulated in human follicular fluid and granulosa-lutein cells (hGL) of OHSS patients and could contribute to the development of OHSS by downregulating steroidogenic acute regulatory protein (StAR) expression. However, whether the same is true for the other two members of the TGF-β family, TGF-β2 and -β3, remains unknown. We showed that all three TGF-β isoforms were expressed in human follicular fluid. In comparison, TGF-β1 was expressed at the highest level, followed by TGF-β2 and TGF-β3. Compared to non-OHSS patients, follicular fluid levels of TGF-β1 and TGF-β3 were significantly upregulated in OHSS patients. The same results were observed in mRNA levels of TGF-β isoforms in hGL cells and ovaries of OHSS rats. In addition, StAR mRNA levels were upregulated in hGL cells of OHSS patients and the ovaries of OHSS rats. Treatment cells with TGF-β isoforms downregulated the StAR expression with a comparable effect. Moreover, activations of SMAD3 signaling were required for TGF-β isoforms-induced downregulation of StAR expression. This study indicates that follicular fluid TGF-β1 and TGF-β3 levels could be used as biomarkers and therapeutic targets for the OHSS.

3D Microtissues Mimic the Architecture, Estradiol Synthesis, and Gap Junction Intercellular Communication of the Avascular Granulosa

Humans are consistently exposed to thousands of untested chemicals that have been detected in the follicular fluid of the ovaries, and can disrupt reproductive health. Human granulosa cells (GCs) are the functional unit of the ovarian follicle with steroidogenic and signaling activities, and play a pivotal role in oocyte development. During follicle progression, GCs multiply to form a 3D avascular structure, and establish gap junction intercellular communication (GJIC) that is critical to maintaining optimal viability and function. We developed a high-throughput in vitro platform of human GCs for the screening of chemicals that can impact GJIC and estradiol (E2) production of human granulosa. Our granulosa 3D microtissues fabricated with human ovarian granulosa-like tumor KGN cells are multicell-layered structures that mimic the avascular granulosa layers surrounding the oocyte. These microtissues robustly expressed the steroidogenic CYP19 aromatase enzyme and GJIC intercellular membrane channel, connexin 43. Granulosa microtissues produced E2 at rates comparable to primary human GCs as previously reported. E2 production was suppressed by the CYP19 inhibitor, letrozole, and induced by CYP19 activators, bisphenol A at 100 µM, and genistein at 100 µM. Granulosa microtissues displayed active GJIC function, as demonstrated by the connexin 43-dependent diffusion of calcein fluorescent dye from microtissue surface to the core using high-throughput confocal microscopy in conjunction with our open-sourced automated image analysis tool. Overall, our 3D human granulosa screening platform is highly promising for predictive and efficient in vitro toxicity testing to screen for chemicals that contaminate follicular fluid and may affect fertility.

BMP-9 downregulates StAR expression and progesterone production by activating both SMAD1/5/8 and SMAD2/3 signaling pathways in human granulosa-lutein cells obtained from gonadotropins induced ovarian cycles

Bone morphogenetic proteins (BMPs) are expressed in different cell types of the human ovarian follicle and play important roles in the regulation of ovarian function. BMP-9, also known as growth differentiation factor-2 (GDF-2), belongs to the transforming growth factor-beta (TGF-β) superfamily. BMP-9 is mainly synthesized in the liver and secreted into the blood which allows it to regulate various physiological and pathological functions. To date, the expression of BMP-9 in the human ovary and its function in human granulosa cells remains unknown. In the present study, we detect the protein expression of BMP-9 in the human follicular fluid. Using the primary culture of human granulosa-lutein (hGL) cells obtained from patients undergoing in vitro fertilization as a cell model, we show that treatment with BMP-9 downregulates steroidogenic acute regulatory protein (StAR) expression and suppresses progesterone (P4) production. The expression levels of the P450 side-chain cleavage enzyme (P450scc) and 3β-hydroxysteroid dehydrogenase (3β-HSD) are not affected by BMP-9 treatment. Mechanistically, treatment of hGL cells with BMP-9 activates both SMAD1/5/8 and SMAD2/3 signaling pathways. Blocking the activations of SMAD1/5/8 and SMAD2/3 by pharmacological inhibitors or knockdown of SMAD4 attenuates the inhibitory effects of BMP-9 on StAR expression and P4 production. This study reveals a novel function of BMP-9 in the regulation of ovarian steroidogenesis.

Upregulation of AREG, EGFR, and HER2 contributes to increased VEGF expression in granulosa cells of patients with OHSS†

Ovarian hyperstimulation syndrome (OHSS) is a serious iatrogenic complication in women undergoing induction of ovulation with human chorionic gonadotropin (hCG) for assisted reproductive techniques. Amphiregulin (AREG) is the most abundant epidermal growth factor receptor (EGFR) ligand expressed in human granulosa cells and follicular fluid and can be upregulated by luteinizing hormone (LH)/hCG. However, whether the expression levels of AREG, EGFR, and HER2 change in the granulosa cells of OHSS patients remains unknown. If it does, whether these molecules are involved in the development of OHSS requires investigation. In the present study, we showed that AREG, EGFR, and HER2 transcripts in granulosa cells as well as follicular fluid AREG proteins were elevated in OHSS patients. Increased AREG levels were associated with transcript levels and follicular content of vascular endothelial growth factor (VEGF), the marker for OHSS pathology. Treatment of cultured granulosa cells with AREG stimulated VEGF expression and secretion, with granulosa cells from OHSS patients showing more rapid and pronounced increases than the non-OHSS group. In addition, siRNA-mediated knockdown of EGFR and AREG attenuated the hCG-induced upregulation of VEGF. This study demonstrated that granulosa cell-secreted AREG plays an important role in the development of OHSS, suggesting that the EGFR/HER2-mediated signaling could be a novel drug target for the prevention and treatment of OHSS.

Utilising FGF2, IGF2 and FSH in serum-free protocol for long-term in vitro cultivation of primary human granulosa cells

Human granulosa cells acquired as leftover from IVF treatment can be used to study infertility problems and are a valuable tool in the research of follicle maturation and ovulation. There is a need for more defined and long-term culture protocols for studying the response of granulosa cells upon treatment with selected hormones/chemicals. In the current study, we tested the effect of adding FGF2, IGF2 and FSH into defined basal medium in order to find culture conditions that would support proliferation of cumulus and mural granulosa cells along with the expression of common granulosa cell type markers such as FSHR, AMHR2, LHR and CYP19A1. We found that FGF2, IGF2 together with FSH helped to retain granulosa cell marker expression while supporting cell survival at least for two weeks of culture. The defined serum-free culture conditions for long-term culturing will be valuable in providing new standards in the research of human granulosa cells.

Melatonin induces progesterone production in human granulosa-lutein cells through upregulation of StAR expression

Steroidogenic acute regulatory protein (StAR) mediates the rate-limiting step in ovarian steroidogenesis and progesterone (P4) synthesis. Melatonin and its receptors are expressed in human granulosa cells, and have been shown to influence basal P4 production. However, previous studies addressing the regulation of StAR expression by melatonin and its impact on P4 secretion yielded contradictory results. Here, we demonstrate that melatonin upregulates StAR expression in primary cultures of human granulosa-lutein (hGL) cells obtained from women undergoing in vitro fertilization (IVF). Using pharmacological inhibitors, we show that the stimulatory effect of melatonin on StAR expression is mediated via both MT1 and MT2 melatonin receptors. Melatonin exposure activates the PI3K/AKT signaling pathway and its inhibition attenuates the stimulatory effect of melatonin on StAR expression. Moreover, siRNA-mediated knockdown of StAR abolishes melatonin-induced P4 production. Importantly, clinical analyses demonstrate that melatonin levels in human follicular fluid are positively correlated with P4 levels in serum. By illustrating the potential physiological role of melatonin in the regulation of StAR expression and P4 production in hGL cells, our results may serve to improve current strategies used to treat clinical infertility.

The role of GPR1 signaling in mice corpus luteum

Chemerin, a chemokine, plays important roles in immune responses, inflammation, adipogenesis, and carbohydrate metabolism. Our recent research has shown that chemerin has an inhibitory effect on hormone secretion from the testis and ovary. However, whether G protein-coupled receptor 1 (GPR1), the active receptor for chemerin, regulates steroidogenesis and luteolysis in the corpus luteum is still unknown. In this study, we established a pregnant mare serum gonadotropin-human chorionic gonadotropin (PMSG-hCG) superovulation model, a prostaglandin F2α (PGF2α) luteolysis model, and follicle and corpus luteum culture models to analyze the role of chemerin signaling through GPR1 in the synthesis and secretion of gonadal hormones during follicular/luteal development and luteolysis. Our results, for the first time, show that chemerin and GPR1 are both differentially expressed in the ovary over the course of the estrous cycle, with highest levels in estrus and metestrus. GPR1 has been localized to granulosa cells, cumulus cells, and the corpus luteum by immunohistochemistry (IHC). In vitro, we found that chemerin suppresses hCG-induced progesterone production in cultured follicle and corpus luteum and that this effect is attenuated significantly by anti-GPR1 MAB treatment. Furthermore, when the phosphoinositide 3-kinase (PI3K) pathway was blocked, the attenuating effect of GPR1 MAB was abrogated. Interestingly, PGF2α induces luteolysis through activation of caspase-3, leading to a reduction in progesterone secretion. Treatment with GPR1 MAB blocked the PGF2α effect on caspase-3 expression and progesterone secretion. This study indicates that chemerin/GPR1 signaling directly or indirectly regulates progesterone synthesis and secretion during the processes of follicular development, corpus luteum formation, and PGF2α-induced luteolysis.

Luteinizing hormone/chorionic gonadotrophin receptor overexpressed in granulosa cells from polycystic ovary syndrome ovaries is functionally active

Polycystic ovarian syndrome (PCOS) is associated with anovulatory infertility. Luteinizing hormone/chorionic gonadotrophin receptor (LHCGR), which is critical for ovulation, has been suggested to be expressed prematurely in the ovarian follicles of women with PCOS. This study aimed to analyse the expression and activity of LHCGR in ovarian granulosa cells from PCOS patients and the involvement of ARF6 small GTPase in LHCGR internalization. Granulosa cells (GC) isolated from follicular fluid collected during oocyte retrieval from normal women (n = 19) and women with PCOS (n = 17) were used to study differences in LHCGR protein expression and activity between normal and PCOS patients. LHCGR expression is up-regulated in GC from PCOS women. LHCGR in PCOS GC is functionally active, as shown by increased cAMP production upon human gonadotrophin (HCG)-stimulation. Moreover, ARF6 is highly expressed in GC from PCOS patients and HCG-stimulation increases the concentrations of active ARF6. The inhibition of ARF6 activation attenuates HCG-induced LHCGR internalization in both normal and PCOS GC, indicating that there are no alterations in LHCGR internalisation in GC from PCOS. In conclusion, the expression and activation of LHCGR and ARF6 are up-regulated in GC from PCOS women but the mechanism of agonist-induced LHCGR internalization is unaltered.

Altered endothelin expression in granulosa-lutein cells of women with polycystic ovary syndrome

AIMS

To examine the levels of endothelin system components in granulosa lutein cells (GLCs) of women with PCOS and compare them to normally ovulating women undergoing In Vitro Fertilization (IVF). Polycystic ovary syndrome (PCOS) is one of the most common endocrine-metabolic disorders in women of reproductive age. Endothelins are locally produced by endothelial and granulosa cells of the preovulatory follicle. Abnormal expression or production of endothelins may be a contributing factor in PCOS pathogenesis.

MAIN METHODS

Follicular aspirates containing GLCs were obtained from PCOS and normally ovulating patients undergoing oocyte retrieval during the IVF cycle. RNA was extracted and endothelin system components were quantified using real-time PCR. GLCs were cultured in basal media for 7 days, and then challenged with various luteinizing agents (luteinizing hormone, hCG, or forskolin) for 24 h.

KEY FINDINGS

In GLCs from women with PCOS, Endothelin-1 mRNA expression was elevated (2.2-fold) as compared with normally ovulating women, whereas endothelin-2 mRNA was reduced (1.8-fold). ET receptors and endothelin-converting enzyme showed the same expression levels in the two groups. In vitro modeling showed that although the steroidogenic response was preserved in GLC, endothelin expression levels were not exhibited in vitro in their original pattern.

SIGNIFICANCE

Dysregulation of ovarian endothelin expression may induce a pathologic ovulation pattern characteristic of PCOS.

Establishment of a human nonluteinized granulosa cell line that transitions from the gonadotropin-independent to the gonadotropin-dependent status

The ovary is a complex endocrine organ responsible for steroidogenesis and folliculogenesis. Follicles consist of oocytes and two primary steroidogenic cell types, the granulosa cells, and the theca cells. Immortalized human granulosa cells are essential for researching the mechanism of steroidogenesis and folliculogenesis. We obtained granulosa cells from a 35-yr-old female and immortalized them by lentivirus-mediated transfer of several genes so as to establish a human nonluteinized granulosa cell line (HGrC1). We subsequently characterized HGrC1 and investigated its steroidogenic performance. HGrC1 expressed enzymes related to steroidogenesis, such as steroidogenic acute regulatory protein, CYP11A, aromatase, and gonadotropin receptors. Stimulation with FSH increased the mRNA levels of aromatase, which consequently induced the aromatization of androstenedione to estradiol. Activin A increased the mRNA levels of the FSH receptor, which were synergistically up-regulated with FSH stimulation. HGrC1 also expressed a series of ligands and receptors belonging to the TGF-β superfamily. A Western blot analysis showed that bone morphogenetic protein (BMP)-4, BMP-6, and BMP-7 phosphorylated small mother against decapentaplegic (Smad)1/5/8, whereas growth differentiation factor-9 phosphorylated Smad2/3. BMP-15 and anti-Müllerian hormone phosphorylated Smad1/5/8 while also weakly phosphorylating Smad2/3. These results indicate that HGrC1 may possess the characteristics of granulosa cells belonging to follicles in the early stage. HGrC1 might also be capable of displaying the growth transition from a gonadotropin-independent status to gonadotropin-dependent one.

Induction of G protein-coupled estrogen receptor (GPER) and nuclear steroid hormone receptors by gonadotropins in human granulosa cells

Estradiol and progesterone mediate their actions by binding to classical nuclear receptors, estrogen receptor α (ERα) and estrogen receptor β (ERβ) and progesterone receptor A and B (PR-A and PR-B) and the non-classical G protein-coupled estrogen receptor (GPER). Several animal knock-out models have shown the importance of the receptors for growth of the oocyte and ovulation. The aim of our study was to identify GPER in human granulosa cells (GC) for the first time. Moreover, the effect of different doses of gonadotropins on estrogen and progesterone receptors in the human ovary should be investigated as follicle stimulating hormone (FSH) and luteinizing hormone (LH) are also responsible for numerous mechanisms in the ovary like induction of the steroid biosynthesis. Human GC were cultured in vitro and stimulated with different doses of recombinant human FSH or LH. Receptor expression was analyzed by immunocytochemistry and quantitative real-time RT-PCR. GPER could be identified for the first time in human GC. It could be shown that high concentrations of LH increase GPER protein expression. Furthermore FSH and LH increased ERβ, PR-A and PR-B significantly on protein level. These findings were verified for high doses of FSH and LH on mRNA level. ERα was not affected with FSH or LH. We assume that gonadotropins induce GPER, ERβ and PR in luteinized granulosa cells.

Expression of adrenomedullin in human ovaries, ovarian sex cord-stromal tumors and cultured granulosa-luteal cells

The aim of the present study was to characterise the expression pattern of the multifunctional vasoactive peptide adrenomedullin (ADM) in human ovarian tumors, and to find hormonal regulators of ADM expression in human ovaries. The expression of ADM messenger RNA (mRNA) was higher in granulosa cell tumors than in fibrothecomas and normal ovaries, as analysed by Northern blots. In normal ovaries, ADM immunoreactivity was localised in both granulosa and thecal cells. Eight of the 90 granulosa cell tumors (9%) showed moderate and 53 (59%) weak ADM immunoreactivity, whereas 27% (11/41) of the fibrothecomas displayed weak ADM staining. FSH, protein kinase A activator (Bu)(2)cAMP, prostaglandin E(2) (PGE(2)), activin A and the broad protein kinase regulator staurosporine decreased ADM mRNA accumulation in cultured granulosa-luteal cells time- and dose-dependently. FSH, (Bu)(2)cAMP and PGE(2) increased progesterone secretion and the accumulation of the steroidogenic acute regulatory protein mRNA in these cells. In conclusion, ADM is expressed in normal human ovaries and sex cord-stromal tumors, particularly in those of granulosa cell origin. FSH, PGE(2,) (Bu)(2)cAMP and activin A suppress ADM gene expression in granulosa-luteal cells. Expression of ADM in human ovaries and its hormonal regulation in granulosa cells suggests a paracrine role for ADM in ovarian function.

Effects of trichlorfon on progesterone production in cultured human granulosa-lutein cells

Trichlorfon, a widely used organophophorus pesticide, has been reported to disrupt reproductive function in human and animal. However, the mechanisms have not been clearly elucidated. In the present study, the effects of trichlorfon on the biosynthesis of progesterone in the primary human granulosa-lutein cells (hGLCs) and the related pathway were investigated. Results showed that progesterone production in hGLCs treated with trichlorfon decreased significantly while cell viability was not affected. Trichlorfon also inhibited FSH-stimulated progesterone production, and this inhibition could not be reversed by 8-bromo-cAMP. However, trichlorfon did not affect the intracellular cAMP contents in the basal and FSH-stimulated conditions. These results suggested that the site in the steroid biosynthesis pathway affected by trichlorfon occurred downstream of PKA activation in hGLCs. Furthermore, our results found that 22(R)-hydroxycholesterol (22R-HC) could remove the inhibitory action of trichlorfon on progesterone biosynthesis, indicating that trichlorfon caused a disruption of cholesterol transport across mitochondrial membranes, which was further confirmed by the observation that trichlorfon dose-dependently inhibited the mRNA level of the steroidogenic acute regulatory protein (StAR). These results suggested that trichlorfon inhibited steroidogenesis in hGLCs by reducing StAR gene expression, which may further contribute to the pathogenesis of trichlorfon-induced reproductive dysfunction.

Expression of inhibin-activin subunits, follistatin and smads in granulosa-luteal cells collected at oocyte retrieval

PURPOSE

To examine the expression of inhibin-activin subunits, follistatin, and Smads 2, 3 and 4 in granulosa-luteal cells at the time of oocyte retrieval.

METHODS

Quantitative reverse transcriptase-polymerase chain reaction was performed to quantify the mRNA expression of the investigated genes: inhibin alpha-subunit, inhibin-activin betaA- and betaB-subunits, follistatin, and Smads 2, 3 and 4.

RESULTS

alpha-, betaA- and betaB-subunits of inhibin-activin, and follistatin were all well expressed in granulosa-luteal cells obtained from either dominant or cohort follicles. alpha-subunits strongly correlated with Smad2 (p < 0.001). betaA-subunit significantly correlated with Smad4, p < 0.001. betaB-subunit significantly correlated with Smad2, p = 0.002, and follistatin expression strongly correlated with the expression of Smads 2 and 4 (p < 0.001 and = 0.007 respectively).

CONCLUSIONS

We found, for the first time that inhibin-activin betaB-subunit mRNA was well expressed in human granulosa-luteal cells obtained from either dominant or cohort follicles. alpha-, betaA- and betaB-subunits and follistatin correlated with Smads to varied degrees, suggesting the active roles of the above genes at the time of oocyte retrieval.

Primate granulosa cell response via prostaglandin E2 receptors increases late in the periovulatory interval

Successful ovulation requires elevated follicular prostaglandin E2 (PGE2) levels. To determine which PGE2 receptors are available to mediate periovulatory events in follicles, granulosa cells and whole ovaries were collected from monkeys before (0 h) and after administration of an ovulatory dose of hCG to span the 40-h periovulatory interval. All PGE2 receptor mRNAs were present in monkey granulosa cells. As assessed by immunofluorescence, PTGER1 (EP1) protein was low/nondetectable in granulosa cells 0, 12, and 24 h after hCG but was abundant 36 h after hCG administration. PTGER2 (EP2) and PTGER3 (EP3) proteins were detected by immunofluorescence in granulosa cells throughout the periovulatory interval, and Western blotting showed an increase in PTGER2 and PTGER3 levels between 0 h and 36 h after hCG. In contrast, PTGER4 (EP4) protein was not detected in monkey granulosa cells. Granulosa cell response to PGE2 receptor agonists was examined 24 h and 36 h after hCG administration, when elevated PGE2 levels present in periovulatory follicles initiate ovulatory events. PGE2 acts via PTGER1 to increase intracellular calcium. PGE2 increased intracellular calcium in granulosa cells obtained 36 h, but not 24 h, after hCG; this effect of PGE2 was blocked by a PTGER1 antagonist. A PTGER2-specific agonist and a PTGER3-specific agonist each elevated cAMP in granulosa cells obtained 36 h, but not 24 h, after hCG. Therefore, the granulosa cells of primate periovulatory follicles express multiple receptors for PGE2. Granulosa cells respond to agonist stimulation of each of these receptors 36 h, but not 24 h, after hCG, supporting the hypothesis that granulosa cells are most sensitive to PGE2 as follicular PGE2 levels peak, leading to maximal PGE2-mediated periovulatory effects just before ovulation.

Purification of granulosa cells from human ovarian follicular fluid using granulosa cell aggregates

Human follicular fluid can provide a source of human granulosa cells for scientific study. However, removing potentially contaminating cells, such as white and red blood cells, is important for molecular and in vitro studies. We have developed a purification technique for human granulosa cells based on the selection of cellular aggregates. Human granulosa cells from 21 IVF patients were collected. A 50% Percoll gradient was used to remove red blood cells, and granulosa cell aggregates were collected, washed and processed for histology, electron microscopy, flow cytometry analysis, cell culture and RNA extraction. Granulosa cell aggregates were found to be homogeneous and free of white blood cells after histological and electron microscopic analysis. White blood cell contamination, measured by flow cytometry, was found to be between 2 and 4%. Polymerase chain reaction analysis revealed expression of known human granulosa cell genes and a white blood cell marker. Human granulosa cells grown in vitro showed flattened fibroblast-like morphology with lipid droplets consistent with previous reports. Cultured cells expressed the FSH receptor. Selection of human granulosa cell aggregates following centrifugation through a Percoll gradient provides an efficient method of selecting granulosa cells, suitable for both molecular and in vitro studies.

Carbaryl inhibits basal and FSH-induced progesterone biosynthesis of primary human granulosa-lutein cells

Carbaryl is known to impede female reproductive function, however, the mechanisms through which the adverse effects are mediated are not clearly elucidated. In order to get insight into the mechanisms, this study was conducted to raise fresh concerns about the potential effects of carbaryl on steroidogenesis by primary human granulosa-lutein cells (hGLCs) and explore the possible nature of this action. hGLCs were co-incubated with various concentrations of carbaryl at 0, 1, 5, 25, 125 micromol/L for 24 h to examine effects of this carbamate pesticide on progesterone accumulation. We observed that the carbaryl inhibited basal and FSH-induced progesterone production in a dose-dependent manner. We also investigated the effects of carbaryl on 22(R)-hydroxycholesterol (22R-HC)-stimulated progesterone yield, basal and FSH-stimulated StAR gene expression and cyclic adenosine monophosphate (cAMP) production, as well as forskolin (non-specific activator of adenylyl cyclase)-induced progesterone and cAMP production of hGLCs. We found that the decreased progesterone biosynthesis was accompanied with a reduced cAMP abundance on both basal and FSH-induced condition. Furthermore, our results demonstrated that the 22R-HC could remove the carbaryl-induced restraint of progesterone biosynthesis, suggesting that carbaryl caused a disruption of cholesterol transport across mitochondrial membranes, which was further confirmed by the observation that carbaryl inhibited the gene expression of steroidogenic acute regulatory protein (StAR). In addition, the inhibitory effects of carbaryl on progesterone and cAMP production were completely reversed by addition of forskolin to the cell culture, which indicated a repaired site on the upstream components of adenylate cyclase or adenylate cyclase per se by carbaryl in the cAMP-mediated signal pathway. All the effects mentioned above were not due to a detrimental action of carbaryl on cell viability by MTS assay. In conclusion, carbaryl may inhibit steroidogenesis, at least in part, by obstructing the delivery of cholesterol over mitochondrial membranes and attenuating cAMP generation.

Localization and gene expression of steroid sulfatase by RT-PCR in cumulus cells and relationship to serum FSH levels observed during in vitro fertilization

Background

The purpose of this study was to localize the expression of steroid sulfatase (STS) in cumulus cells and to determine the relationship between STS mRNA expression and the serum levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol and progesterone.

Methods

The subject group included 49 women (29 to 44 years old) for whom in vitro fertilization treatment was indicated. All subjects gave informed consent. One hundred fourteen samples of cumulus-oocyte complex (COC) were obtained under microscopic observation. Part of the COC was stained by STS antibody. RNA was extracted by phenol-chloroform method and real-time PCR was performed. Serum of each patient was collected and was measured by ELISA.

Results

Some of the cumulus samples were stained by STS antibody. The expression of STS mRNA in all samples was confirmed by quantitative RT-PCR. Although there was no significant correlation between the level of STS mRNA and the serum levels of estradiol, progesterone and LH, there was a statistically significant negative correlation between the level of STS mRNA expression and the serum level of FSH (n = 105, p = 0.018, r = -0.22).

Conclusion

These results have demonstrated for the first time the expression of STS in cumulus cells by immunohistological stainings and real-time RT-PCR. STS expression in cumulus cells may be related to the control of the local steroidal environment in the oocyte. Serum FSH may control STS mRNA expression from the results of RT-PCR, although the correlation was low.

Ovarian granulosa cell lines

The ovary is a complex endocrine gland responsible for production of sex steroids and is the source of fertilizable ova for reproduction. It also produces various growth factors, transcription factors and cytokines that assist in the complex signaling pathways of folliculogenesis. The ovary possesses two primary steroidogenic cell types. The theca cells (and to a lesser extent, the stroma) are responsible for androgen synthesis, and the granulosa cells are responsible for conversion of androgens to estrogens, as well as progesterone synthesis. These cells undergo a transformation in the luteal phase of the menstrual cycle, converting them from estrogen producing, to predominantly progesterone producing cells. Understanding the molecular mechanisms regulating these cells is essential in understanding the regulation of steroidogenesis and reproduction. Creation of appropriate in vitro cell model systems can provide important tools for the study of ovarian function. This has led to the development of ovarian steroidogenic cell lines in several laboratories. Developing theca cell lines has met with limited success. Conversely, numerous human and animal granulosa cell lines have been developed. This review will discuss the existing granulosa cell lines and their characteristics.

Expression of integrin fraction and adhesion molecules on human granulosa cells and its relation with oocyte maturity and follicular steroidogenesis

PURPOSE

To study the correlation between the expression of integrin fractions and adhesion molecules on granulosa cells (GC) and follicular development.

METHODS

GC and follicular fluid (FF) were obtained at oocyte retrieval for ICSI. Expression of adhesion molecules on GC was studied by flow cytometry. Statistics were evaluated using the Student t test and simple linear regression analysis.

RESULTS

alpha5 integrin fraction was significantly (p < 0.01) higher, while alpha6 fraction and CD9 were significantly (p < 0.01 and p < 0.001, respectively) lower in GC from FF with metaphase II oocytes. A direct significant correlation was observed between FF progesterone and the alpha5 expression on GC (r = 0.54). In contrast, an inverse significant correlation was observed between FF progesterone level and the expression of alpha6 and CD9 (r = -0.40 and -0.41, respectively).

CONCLUSIONS

The expression pattern for integrin fractions and adhesion molecules may be of predictive value in assessing the state of differentiation of the human follicle.

Alterations of FSH-stimulated progesterone production and calcium homeostasis in primarily cultured human luteinizing-granulosa cells induced by fenvalerate

Fenvalerate, a synthetic pyrethroid, is widely used in agriculture and other domestic applications in China. Recently, Fenvalerate has been suspected to be one of the endocrine-disrupting chemicals (EDC). In this study, we investigated the effects of fenvalerate on follicle-stimulating hormone (FSH)-stimulated progesterone (P4) production by human ovarian luteinizing-granulosa cells (hGLCs). After 24 h incubation, fenvalerate inhibited FSH-stimulated P4 production. At the same time, FSH-stimulated cAMP also decreased. Due to calcium and Ca2+ -calmodulin (CaM) system involving gonadotropin-stimulated steroidogenesis by granulosa cells, we then evaluated the effects of fenvalerate on trifluoperazine (TFP)- and verapamil-driven FSH-stimulated P4 production. The results showed that calcium or calmodulin might play a role in fenvalerate-induced alterations in FSH-stimulated P4 biosynthesis. Then, the effects of fenvalerate on calcium homeostasis in hGLCs were studied. The result showed that 5 microM fenvalerate induced a slow increase in [Ca2+]i in hGLCs by using a fluorescent Ca2+ indicator fluo-3/AM. The changes in total concentration of CaM in hGLCs induced by fenvalerate were evaluated by a method of immunofluorescence. There is a significant increase in all treated groups. In summary, fenvalerate could inhibit FSH-stimulated P4 production. Also, fenvalerate interferes with calcium homeostasis in hGLCs. The effects of fenvalerate on FSH-stimulated ovarian steroidogenesis may be mediated partly through calcium signal.

Differential hormonal regulation of vascular endothelial growth factors VEGF, VEGF-B, and VEGF-C messenger ribonucleic acid levels in cultured human granulosa-luteal cells

The development of ovarian follicles and subsequent corpus luteum formation is accompanied by very active angiogenesis. Ovarian granulosa cells produce vascular endothelial growth factor (VEGF), which is a potent endothelial cell mitogen and an angiogenic agent. The complementary DNAs of two other factors structurally related to VEGF, namely VEGF-B and VEGF-C, were recently cloned, but little is known of their regulation in the ovary. We first studied the expression of the messenger RNAs (mRNAs) of the three VEGF isotypes in freshly isolated human granulosa-luteal (GL) cells obtained at oocyte retrieval for in vitro fertilization. The hormonal regulation of these mRNAs was subsequently studied in primary cultures of human GL cells. Analysis of cultured GL cell RNA by reverse transcription-PCR revealed that these cells express the alternatively spliced transcripts representing 121-, 145-, and 165-amino acid VEGF isoforms. Northern blot hybridization analyses indicated that transcripts of 4.5 and 3.7 kilobases for VEGF, and 1.4 and 2.4 kilobases for VEGF-B and VEGF-C, respectively, are expressed in human GL cells. The basal VEGF mRNA levels declined steadily, whereas VEGF-B mRNA levels were rather invariant over a 10-day culture period of GL cells. In contrast, VEGF-C mRNA levels increased toward the end of culture. For studying the hormonal regulation of VEGF isotype mRNAs, GL cells were treated with hCG, recombinant human FSH, PGE2, as well as 8-bromo-cAMP and 12-O-tetradecanoylphorbol 13-acetate, which activate protein kinase A- and protein kinase C-dependent signaling pathways, respectively. All test agents stimulated the expression of VEGF mRNA levels in a concentration-dependent manner. Time-course studies indicated that all treatments induced VEGF mRNA levels as early as incubation for 2 h, and the effect was sustained up to 48 h. VEGF-B mRNA levels were not regulated by any of the test agents. However, we found that hCG and 8-bromo-cAMP decreased VEGF-C mRNA levels with a maximal response observed at 24 and 48 h after cellular treatment. We conclude that the mRNAs of VEGF, VEGF-B, and VEGF-C are expressed in human GL cells and that their mRNA steady state levels are regulated in cultured human GL cells in an isotype-specific manner. The differential regulation of VEGF, VEGF-B, and VEGF-C in human GL cells suggests that distinct VEGF isotypes may play different roles during the vascularization of the human ovarian follicle and corpus luteum.

Gonadotropic control of secretion of dimeric inhibins and activin A by human granulosa-luteal cells in vitro

PURPOSE

It is well established that human granulosa cells and luteal cells express inhibin/activin subunit protein and secrete immunoreactive inhibin. The gonadotropic control of secretion of different molecular forms of inhibin and activin A by granulosa-luteal cells (G-LCs) was investigated using recently developed specific enzyme immunoassays (EIAs).

METHODS

Granulosa-luteal cells obtained at IVF egg pickup were cultured in a serum-free medium at 37 degrees C in a water-saturated incubator with 5% CO2 for up to 5 days. Experiments with varying concentrations of human FSH, hLH, and hCG were carried out.

RESULTS

FSH raised the secretion of inhibin A and pro-alpha C-containing inhibins after 24 and 48 hr in culture. Inhibin B was raised after 24 hr and activin A was raised after 48 hr of FSH treatment. LH treatment for 24 hr stimulated inhibin A, inhibin B, pro-alpha C, and activin A. hCG stimulated G-LC secretion of inhibin A after 48 hr and pro-alpha C after 24 hr. Paradoxically, inhibin B secretion was inhibited by 1 and 10 ng/ml hCG after 48 hr. Activin A was stimulated by hCG after 24 and 48 hr of incubation. G-LC secretion of estradiol and progesterone was also stimulated significantly by LH and hCG.

CONCLUSIONS

Secretion of dimeric inhibins and activin A is controlled differentially by gonadotropins.