Primary Human Granulosa Cells Research Articles

Pigment epithelium-derived factor (PEDF) negates hyperandrogenic PCOS features.

Polycystic ovary syndrome (PCOS), one of the most common female endocrine disorder, is a prevalent cause of infertility. Hyperandrogenism is a key feature in PCOS and is correlated with increased expression of VEGF and cytokines in the ovaries. We have previously shown that pigment epithelium-derived factor (PEDF), an endogenous protein, presents potent anti-angiogenic and anti-inflammatory activities in the ovary and negates the effects of cytokines and VEGF. Additionally, PEDF plays a role in both pathophysiology and treatment of ovarian-hyperstimulation syndrome (OHSS), frequently seen in PCOS patients. We established hyperandrogenic-PCOS models, both in vivo, using mice exposed prenatally to dihydrotestosterone (DHT) and, in vitro, using human primary granulosa cells (hpGCs) and human granulosa cell line (KGN). In PCOS-induced mice, the mRNA levels of I l-6, V egf and Amh were higher than those of control; yet, treatment with rPEDF decreased these levels. Moreover, treating OHSS-induced PCOS-mice with rPEDF alleviated all OHSS symptoms. Stimulation of hpGCs with DHT resulted in downregulation of PEDF mRNA expression, concomitantly with a significant increase in IL-6 and IL-8 mRNAs expression. However, co-stimulation of DHT with rPEDF attenuated the increase in cytokines expression. The anti-inflammatory effect of PEDF was found to be mediated via PPARγ pathway. Our findings suggest that rPEDF treatment may normalize the ovarian angiogenic-inflammatory imbalance, induced by PCOS-associated hyperandrogenism. Moreover, the therapeutic potency of PEDF in preventing OHSS symptomes offers a rationale for using PEDF as novel physiological treatment for PCOS sequels.

The effects of mitochondrial dysfunction on energy metabolism switch by HIF-1α signalling in granulosa cells of polycystic ovary syndrome.

This study aimed to determine the effects of mitochondrial dysfunction on energy metabolism of granulosa cells (GCs) and the competence of oocytes in polycystic ovary syndrome (PCOS). A total of 107 patients who underwent controlled ovarian hyperstimulation (COH) were enrolled. The clinical outcomes of patients with and without PCOS under in vitro fertilisation-embryo transfer (IVF-ET) were compared. Human primary GCs were exposed to mitochondrial and glycolysis inhibitors. Then, the related indicators of mitochondrial activity and glycometabolism were compared with controls. The viability of GCs after mitochondrial inhibitors was also determined. In PCOS patients, the number of retrieved oocytes significantly increased, but the high-quality embryos, available embryos, and high-quality blastocyst formation obviously decreased (p < 0.05). Furthermore, the mitochondrial membrane potential, adenosine triphosphate (ATP) content, mitochondrial DNA (mtDNA) copy number, and HIF-1α mRNA levels in GCs decreased, while the levels of reactive oxygen species increased (p < 0.05). Mitochondrial inhibitors reduced the mitochondrial function, but increased the HIF-1α, GLUT1, LDHA, and PFKP gene expression. Glucose consumption gradually increased at 24, 48, and 72 hours of GC culture after CCCP treatment, and the viability of cells tested by CCK-8 increased (p < 0.05). GCs are dependent on mitochondrial respiration and glycolysis for energy provision. Mitochondrial dysfunction accompanied by abnormal glycolysis was observed in PCOS patients, which affects the switch of energy from metabolic to glycolytic. The failure of transformation to glycolysis and low HIF-1a expression in GCs during the development of follicles might be correlated with the low oocyte competence of PCOS.

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.

Elevated levels of arachidonic acid metabolites in follicular fluid of PCOS patients.

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in reproductive-age women usually accompanied by lipid metabolic disorders. However, it remains unknown whether arachidonic acid (AA) and its metabolites in follicular fluid (FF) were altered in PCOS patients. This study was intended to measure the levels of AA and its metabolites in the FF of non-obese PCOS patients that underwent in vitro fertilization (IVF) and to explore the possible causes of the alterations. Thirty-nine non-obese women with PCOS and 30 non-obese women without PCOS were enrolled. AA and its metabolites were measured by liquid chromatography-mass spectrometry. The levels of AA metabolites generated via cyclooxygenase-2 (COX-2) pathway and cytochrome P450 epoxygenase pathway but not lipoxygenase (LOX) pathway were significantly higher in the FF of PCOS patients. The metabolites generated via COX-2 pathway were significantly correlated with levels of testosterone and fasting insulin in serum. The in vitro study further demonstrated that insulin but not testosterone could promote the IL-1β and hCG-induced COX-2 expression and prostaglandin E2 (PGE2) secretion in primary human granulosa cells. In conclusion, there was an elevation in AA metabolites in FF of PCOS patients. Insulin played a pivotal role in the increased AA metabolites generated via COX-2, which could be interpreted as another novel molecular pathophysiological mechanism of PCOS.

Regulation of Insulin-Like Growth Factor 2 by Oocyte-Secreted Factors in Primary Human Granulosa Cells

Human granulosa cells (hGCs) produce and respond to insulin-like growth factor 2 (IGF2) but whether the oocyte participates in IGF2 regulation in humans is unknown. To determine the role of oocyte-secreted factors (OSFs) such as growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) in IGF2 production by hGCs. Primary human cumulus GCs in culture. University infertility center. GCs of women undergoing in vitro fertilization. Cells treated with GDF9 and BMP15 in the presence of vehicle, follicle-stimulating hormone (FSH), dibutyryl cyclic-AMP (dbcAMP), or mothers against decapentaplegic homolog (SMAD) inhibitors. Quantification of mRNA, protein, promoter activity, and DNA methylation. FSH stimulation of IGF2 (protein and mRNA) was significantly potentiated by the GDF9 and BMP15 (G+B) combination (P < 0.0001) in a concentration-dependent manner showing a maximal effect at 5 ng/mL each. However, GDF9 or BMP15 alone or in combination (G+B) have no effect on IGF2 in the absence of FSH. FSH stimulated IGF2 promoter 3 activity, but G+B had no effect on promoter activity. G+B potentiated IGF2 stimulation by cAMP. SMAD3 inhibitors inhibited G+B enhancement of IGF2 stimulation by FSH (P < 0.05) but had no effect on FSH induction. Moreover, inhibition of insulin-like growth factor receptor partially blocked G+B potentiation of FSH actions (P < 0.009). For the first time, we show that the oocyte actively participates in the regulation of IGF2 expression in hGCs, an effect that is mediated by the specific combination of G+B via SMAD2/3, which in turn target mechanisms downstream of the FSH receptor.

OR33-3 Salt Inducible Kinase is a Negative Regulator of FSH in Ovarian Granulosa Cells

Ovulation is the pinnacle of folliculogenesis, a process requiring granulosa cell (GC) proliferation and differentiation to form preovulatory follicles. In human and rodent GCs, we discovered that pituitary follicle-stimulating hormone (FSH) and insulin-like growth factors (IGFs) have interdependent effects on GC differentiation, converging on the activation of the serine/threonine kinase AKT. However, the AKT-controlled mechanisms involved in GC differentiation remain unclear. Here, we examined the role of salt-inducible kinases (SIKs), a known target of AKT, on the stimulation of GC differentiation by FSH. We first examined the expression of the three SIK isoforms in ovarian human and rat GCs and observed that SIK1 is expressed at low levels. In contrast, SIK2 and SIK3 are highly expressed with SIK3 being the strongest. Immunofluorescence of rat GCs and immunohistochemistry of rat ovaries reveal that all SIK isoforms are expressed in the GCs at levels that correlated with the mRNA levels for each isoform (SIK3>SIK2>SIK1). To determine if SIKs play any role in the response of GCs to FSH, we treated rat and human GCs with four different and specific inhibitors of SIK activity. We observed that SIK inhibition potentiated the stimulatory effect of FSH on aromatase mRNA expression, a marker of GC differentiation. This effect was also observed on aromatase protein expression and on the production of estradiol (E2). Thus, E2 levels in cells treated with FSH and SIK inhibitors were significantly higher than treatment with FSH alone. Next, to investigate whether SIK inhibition affects the transcription of the aromatase gene, we transfected rat and human primary GCs with an empty luciferase reporter or a reporter carrying the aromatase promoter. We observed that aromatase promoter activity was significantly higher in cells treated with FSH and SIK inhibitors than FSH alone. Since FSH requires the presence of the IGF1R to activate AKT, we measured SIK expression in GC-specific IGF1R knockout mice and observed that all SIK isoforms are expressed at significantly higher levels when compared to control mice, suggesting that the IGF1R is involved in repressing SIK expression. Moreover, in vivo administration of a SIK inhibitor was able to recover FSH responsiveness in GC-specific IGF1R knockout mice. These findings demonstrate for the first time the involvement of SIK in the regulation of GC differentiation and contribute to our understanding of the mechanisms regulated by FSH and IGFs in the control of aromatase expression.

Higher melatonin in the follicle fluid and MT2 expression in the granulosa cells contribute to the OHSS occurrence

BackgroundOvarian hyperstimulation syndrome (OHSS) is a common and severe complication for patients undergoing IVF/ICSI-ET. Melatonin widely participates in the regulation of female reproductive endocrine activity. However, whether melatonin participates in the progression of OHSS is largely unknown. This study aims to identify the predictive value of follicular fluid (FF) melatonin for OHSS establishment and the underlying mechanism.MethodsAll participants of this case-control study were enrolled at the Reproductive Medicine Center located in the First Affiliated Hospital of Zhengzhou University in China from January to October in 2017. Quantitative real-time PCR and western blot were used to examine the mRNA and protein levels. Primary granulosa cells were extracted and cultured for in vitro studies. Melatonin concentration was measured by ELISA. Logistic analysis and receiver-operating characteristic (ROC) curves were used to evaluate the predicting value of melatonin on OHSS occurrence.Main outcome measuresThe expression level of melatonin receptor 2 (MT2), P450 aromatase cytochrome (aromatase), vascular endothelial growth factor (VEGF), and inducible nitric oxide synthase (iNOS) mRNA in human primary granulosa cells. The concentration of melatonin in FF. The predicting value of melatonin on OHSS and the cut-off value of the prediction.ResultsFF melatonin concentrations were significantly higher in patients with OHSS compared to non-OHSS group (35.94 ± 10.18 ng/mL vs 23.93 ± 10.94 ng/mL, p<0.001). The expression of MT2 mRNA (p = 0.0459) and protein in granulosa cells was also significantly higher in the OHSS group. When using a cut-off level of 27.52 ng/ml, the sensitivity and specificity of FF melatonin to predict OHSS was 84.6 and 74.0%, respectively (p < 0.0001). We also found that melatonin could up-regulates aromatase mRNA, VEGF mRNA expression and down-regulates iNOS mRNA expression in the granulosa cells.ConclusionOHSS patients have higher melatonin in the FF as well as higher MT2 expression in the granulosa cells. The melatonin in FF might be used as an effective predictor for the occurrence of OHSS.

Supraphysiological Concentrations of Bisphenol A Alter the Expression of Extracellular Vesicle-Enriched miRNAs From Human Primary Granulosa Cells.

Bisphenol A (BPA) is a widely used chemical that has been detected in follicular fluid and associated with adverse reproductive effects. Granulosa cells have an important role in follicular growth and oocyte maturation, however, little is known about the biological mechanisms of BPA toxicity on human granulosa cells. In this study, we exposed primary granulosa cells to different concentrations of BPA (0, 20, 200, 2000, and 20000 ng/ml) and used quantitative polymerase chain reaction to measure the expression levels of miRNAs enriched in extracellular vesicles (EV-enriched miRNAs), and cellular levels of selected target genes of differentially expressed EV-enriched miRNAs. We found that exposure to 20000 ng/ml BPA was associated with decreased levels of EV-miR-27b-3p (FC = 0.58, p = .04) and increased levels of its biologically relevant target genes FADD (FC = 1.22, p = .01), IGF1 (FC = 1.59, p = .06), and PPARG (FC = 1.73, p = .001) as compared with the control. In addition, we observed that under the same exposure conditions, the expression levels of miR-27b-3p in granulosa cells were also downregulated (FC = 0.65, p = .03) as compared with the control. Our findings suggest that both cellular and extracellular changes in gene expression may mediate BPA toxicity in granulosa cells.

Lysyl oxidase blockade ameliorates anovulation in polycystic ovary syndrome.

Is overexpression of lysyl oxidase (LOX), an enzyme responsible for the cross-linking of collagens, a cause of anovulation in polycystic ovary syndrome (PCOS)? LOX overexpression was present in PCOS ovaries, due at least in part to interleukin-1β (IL-1β), and inhibition of LOX activity with β-aminopropionitrile (BAPN) ameliorated polycystic ovary morphology and anovulation. Aberrant ovarian extracellular matrix (ECM) remodeling and inflammation may contribute to the development of PCOS. It remains unknown whether proinflammatory IL-1β is a contributing factor for LOX overexpression in PCOS ovaries and whether inhibition of LOX can improve PCOS conditions. LOX and IL-1β abundance in the granulosa cells and follicular fluid was compared between non-PCOS (n = 30) and PCOS (n = 39) patients. The effect and mechanism of IL-1β on LOX expression was examined in cultured primary human granulosa cells. The improvements in PCOS conditions by LOX inhibition with BAPN was investigated in a dehydroepiandrosterone (DHEA)-induced PCOS rat model. The abundance of LOX and IL-1β was measured with quantitative real-time polymerase chain reaction (qRT-PCR), LOX activity assays and enzyme-linked immunosorbent assays (ELISA), respectively. The effect of IL-1β on LOX expression was examined in the presence or absence of inhibitors for signaling molecules and small interfering RNA-mediated knockdown of the putative transcription factor. Chromatin immunoprecipitation assays were conducted to further identify the responsible transcription factor. The role of LOX in ovulation was investigated in a DHEA-induced PCOS rat model with administration of the LOX inhibitor BAPN. The numbers of retrieved total oocytes and MII oocytes were recorded upon ovarian stimulation. Increased abundance of LOX (P < 0.05) and IL-1β (P < 0.05) was observed in the granulosa cells and follicular fluid in PCOS patients. IL-1β increased LOX expression via activation of ERK1/2 and JNK and subsequent activation of the transcription factor c-Jun. Inhibition of LOX with BAPN ameliorated irregular estrous cyclicity (P < 0.05), polycystic ovary morphology and anovulation (P < 0.05) in PCOS rats, but appeared to be ineffective in the improvement of oocyte quality. N/A. Ovarian tissue-directed specific inhibition of LOX in combination with oocyte quality-improving drugs may be more effective in the treatment of PCOS. Inflammation of the ovary is a contributing factor for the aberrant expression of LOX in the PCOS ovary, and inhibition of LOX together with anti-inflammatory therapy may improve the core features of PCOS. This work was supported by National Key R & D Program of China (2017YFC1001403) and Doctorial Innovation Fund of Shanghai Jiao Tong University School of Medicine (BXJ201718). The authors declare no competing financial interests.

Effect of the interaction of metformin and bone morphogenetic proteins on ovarian steroidogenesis by human granulosa cells

In the present study, we studied the effects of metformin and its interactions with the actions of bone morphogenetic proteins (BMPs) on ovarian steroidogenesis. It was revealed that metformin treatment enhanced progesterone production by human granulosa KGN cells and rat primary granulosa cells induced by forskolin and FSH, respectively. In human granulosa cells, it was found that metformin treatment suppressed phosphorylation of Smad1/5/9 activated by BMP-15 compared with that induced by other BMP ligands. Moreover, metformin treatment increased the expression of inhibitory Smad6, but not of that Smad7, in human granulosa cells, while metformin had no significant impact on the expression levels of BMP type-I and -II receptors. Thus, the mechanism by which metformin suppresses BMP-15-induced Smad1/5/9 phosphorylation is likely, at least in part, to be upregulation of inhibitory Smad6 expression in granulosa cells. The results suggest the existence of functional interaction between metformin and BMP signaling, in which metformin enhances progesterone production by downregulating endogenous BMP-15 activity in granulosa cells.

MiR-106a Increases Granulosa Cell Viability and Is Downregulated in Women With Diminished Ovarian Reserve.

Women with diminished ovarian reserve (DOR) have reduced fertility, cardiovascular events, and osteoporosis. Although differential microRNA (miRNA) expression has been described in several ovarian disorders, little is known about the role of miRNAs in the pathogenesis of DOR. Identify differentially expressed miRNAs in DOR and explore the role of miR-106a in human granulosa cell proliferation. miRNA microarray (n = 3) and quantitative reverse transcription polymerase chain reaction (n = 30) were used to examine miRNA expression in serum and granulosa cells from normal-cycling and women with DOR. Primary human granulosa cells were treated alone or in combination with miR-106a mimic, miR-106a inhibitor, apoptosis signal-regulating kinase 1 (ASK1) small interfering RNA (siRNA), or p38 mitogen-activated protein kinase (MAPK) inhibitor (SB203580) before assessment of cell viability and apoptosis. Western blot was used to measure ASK1 protein and phosphorylation/activation of p38 MAPK. Binding of miR-106a to ASK1 mRNA was examined by 3' untranslated region (3'UTR) luciferase analysis. Fifteen miRNAs were differentially expressed (n = 30), and miR-106a was downregulated in serum and granulosa cells of women with DOR. miR-106a mimic increased cell viability and attenuated apoptosis, whereas the converse occurred following treatment with miR-106a inhibitor. miR-106a suppressed ASK1 expression by directly targeting its 3'UTR. miR-106a inhibitor increased p38 MAPK phosphorylation/activation, and this effect was abolished by treatment with ASK1 siRNA. Whereas knockdown of ASK1 abolished the effects of miR-106a inhibitor on cell viability/apoptosis, pretreatment with SB203580 did not significantly alter the effects of miR-106a inhibitor. Downregulation of miR-106a may contribute to the pathogenesis of DOR by reducing granulosa cell viability and promoting apoptosis via enhanced ASK1 signaling.

Abnormality of Klotho Signaling Is Involved in Polycystic Ovary Syndrome.

This study investigated the involvement of the klotho-associated signaling in the apoptosis of granulosa cells (GCs) from the ovaries of patients with polycystic ovary syndrome (PCOS) and PCOS animals. Primary GCs were obtained from 26 healthy women and 43 women with PCOS. The PCOS animal model was established by the injection of dehydroepiandrosterone (DHEA). Klotho protein and associated microRNA expression in human primary GCs and rats' ovarian tissues were measured by Western blot and real-time polymerase chain reaction, respectively. Results showed that significantly lower miR-126-5p and miR-29a-5p microRNA expressions, higher klotho protein expression, lower insulin growth factor 1 (IGF-1R) and Wnt family member 1 (Wnt1) protein expressions, and lower Akt phosphorylation at Ser473 and Thr308 residues were observed in the GCs from patients with PCOS and the ovarian tissues of PCOS rats compared to that in GCs from healthy women and ovarian tissues of normal control rats, respectively. Knockdown of klotho gene expression normalized IGF-1R and Wnt1 protein expressions and Akt phosphorylation in GCs from patients with PCOS and the ovarian tissues from PCOS rats; it also blocked the effects of insulin on apoptosis and proliferation in GCs from patients with PCOS and inhibited caspase-3 activity in ovarian tissues of PCOS rats. Knockdown of klotho gene expression increased the pregnancy rate in DHEA-treated female rats and increased the body weight of their newborns through normalizing the ovarian function and decreasing the formation of cystic follicles. In conclusion, the miR-126-5p, miR-29a-5p/klotho/insulin-IGF-1, Wnt, and Akt signal pathway may be involved in the apoptosis of GCs and subsequent development of PCOS.

Temporal reprogramming of calcium signalling via crosstalk of gonadotrophin receptors that associate as functionally asymmetric heteromers

Signal crosstalk between distinct G protein-coupled receptors (GPCRs) is one mechanism that underlies pleiotropic signalling. Such crosstalk is also pertinent for GPCRs activated by gonadotrophic hormones; follicle-stimulating hormone (FSH) and luteinising hormone (LH), with specific relevance to female reproduction. Here, we demonstrate that gonadotrophin receptor crosstalk alters LH-induced Gαq/11-calcium profiles. LH-induced calcium signals in both heterologous and primary human granulosa cells were prolonged by FSHR coexpression via influx of extracellular calcium in a receptor specific manner. LHR/FSHR crosstalk involves Gαq/11 activation as a Gαq/11 inhibitor abolished calcium responses. Interestingly, the enhanced LH-mediated calcium signalling induced by FSHR co-expression was dependent on intracellular calcium store release and involved Gβγ. Biophysical analysis of receptor and Gαq interactions indicated that ligand-dependent association between LHR and Gαq was rearranged in the presence of FSHR, enabling FSHR to closely associate with Gαq following LHR activation. This suggests that crosstalk may occur via close associations as heteromers. Super-resolution imaging revealed that LHR and FSHR formed constitutive heteromers at the plasma membrane. Intriguingly, the ratio of LHR:FSHR in heterotetramers was specifically altered following LH treatment. We propose that functionally significant FSHR/LHR crosstalk reprograms LH-mediated calcium signalling at the interface of receptor-G protein via formation of asymmetric complexes.

Heterogeneous hCG and hMG commercial preparations result in different intracellular signalling but induce a similar long-term progesterone response in vitro

Are four urinary hCG/menotropin (hMG) and one recombinant preparation characterized by different molecular features and do they mediate specific intracellular signaling and steroidogenesis? hCG and hMG preparations have heterogeneous compositions and mediate preparation-specific cell signaling and early steroidogenesis, although similar progesterone plateau levels are achieved in 24 h-treated human primary granulosa cells in vitro. hCG is the pregnancy hormone marketed as a drug for ARTs to induce final oocyte maturation and ovulation, and to support FSH action. Several hCG formulations are commercially available, differing in source, purification methods and biochemical composition. Commercial hCG preparations for ART or research purposes were compared in vitro. The different preparations were quantified by immunoassay with calibration against the hCG standard (Fifth IS; NIBSC 07/364). Immunoreactivity patterns, isoelectric points and oligosaccharide contents of hCGs were evaluated using reducing and non-reducing Western blotting, capillary isoelectric-focusing immunoassay and lectin-ELISA, respectively. Functional studies were performed in order to evaluate intracellular and total cAMP, progesterone production and β-arrestin 2 recruitment by ELISA and BRET, in both human primary granulosa lutein cells (hGLC) and luteinizing hormone (LH)/hCG receptor (LHCGR)-transfected HEK293 cells, stimulated by increasing hormone concentrations. Statistical analysis was performed using two-way ANOVA and Bonferroni post-test or Mann-Whitney's U-test as appropriate. Heterogeneous profiles were found among preparations, revealing specific molecular weight patterns (20-75 KDa range), isoelectric points (4.0-9.0 pI range) and lectin binding (P < 0.05; n = 7-10). These drug-specific compositions were linked to different potencies on cAMP production (EC50 1.0-400.0 ng/ml range) and β-arrestin 2 recruitment (EC50 0.03-2.0 μg/ml) in hGLC and transfected HEK293 cells (P < 0.05; n = 3-5). In hGLC, these differences were reflected by preparation-specific 8-h progesterone production although similar plateau levels of progesterone were acheived by 24-h treatment (P ≥ 0.05; n = 3). N/A. The biological activity of commercial hCG/hMG preparations is provided in International Units (IU) by in-vivo bioassay and calibration against an International Standard, although it is an unsuitable unit of measure for in-vitro studies. The re-calibration against recombinant hCG,quantified in grams, is based on the assumption that all of the isoforms and glycosylation variants have similar immunoreactivity. hCG/hMG preparation-specific cell responses in vitro may be proposed to ART patients affected by peculiar ovarian response, such as that caused by polycystic ovary syndrome. Otherwise, all the preparations available for ART may provide a similar clinical outcome in healthy women. This study was supported by a grant of the Italian Ministry of Education, University and Research (PRIN 2015XCR88M). The authors have no conflict of interest.

Biological activity mediated by sfingosine-1-phospate receptors in human primary granulosa cells and immortalized granulosa cell line in vitro

Biological activity mediated by sfingosine-1-phospate receptors in human primary granulosa cells and immortalized granulosa cell line in vitro

Estrogen Modulates Specific Life and Death Signals Induced by LH and hCG in Human Primary Granulosa Cells In Vitro.

Luteinizing hormone (LH) and human chorionic gonadotropin (hCG) are glycoprotein hormones used for assisted reproduction acting on the same receptor (LHCGR) and mediating different intracellular signaling. We evaluated the pro- and anti-apoptotic effect of 100 pM LH or hCG, in the presence or in the absence of 200 pg/mL 17β-estradiol, in long-term, serum-starved human primary granulosa cells (hGLC) and a transfected granulosa cell line overexpressing LHCGR (hGL5/LHCGR). To this purpose, phospho-extracellular-regulated kinase 1/2 (pERK1/2), protein kinase B (pAKT), cAMP-responsive element binding protein (pCREB) activation and procaspase 3 cleavage were evaluated over three days by Western blotting, along with the expression of target genes by real-time PCR and cell viability by colorimetric assay. We found that LH induced predominant pERK1/2 and pAKT activation STARD1, CCND2 and anti-apoptotic XIAP gene expression, while hCG mediated more potent CREB phosphorylation, expression of CYP19A1 and procaspase 3 cleavage than LH. Cell treatment by LH is accompanied by increased (serum-starved) cell viability, while hCG decreased the number of viable cells. The hCG-specific, pro-apoptotic effect was blocked by a physiological dose of 17β-estradiol, resulting in pAKT activation, lack of procaspase 3 cleavage and increased cell viability. These results confirm that relatively high levels of steroidogenic pathway activation are linked to pro-apoptotic signals in vitro, which may be counteracted by other factors, i.e., estrogens.

Human LH and hCG stimulate differently the early signalling pathways but result in equal testosterone synthesis in mouse Leydig cells in vitro

BackgroundHuman luteinizing hormone (LH) and chorionic gonadotropin (hCG) are glycoprotein hormones regulating development and reproductive functions by acting on the same receptor (LHCGR). We compared the LH and hCG activity in gonadal cells from male mouse in vitro, i.e. primary Leydig cells, which is a common tool used for gonadotropin bioassay. Murine Leydig cells are naturally expressing the murine LH receptor (mLhr), which binds human LH/hCG.MethodsCultured Leydig cells were treated by increasing doses of recombinant LH and hCG, and cell signaling, gene expression and steroid synthesis were evaluated.ResultsWe found that hCG is about 10-fold more potent than LH in cAMP recruitment, and slightly but significantly more potent on cAMP-dependent Erk1/2 phosphorylation. However, no significant differences occur between LH and hCG treatments, measured as activation of downstream signals, such as Creb phosphorylation, Stard1 gene expression and testosterone synthesis.ConclusionsThese data demonstrate that the responses to human LH/hCG are only quantitatively and not qualitatively different in murine cells, at least in terms of cAMP and Erk1/2 activation, and equal in activating downstream steroidogenic events. This is at odds with what we previously described in human primary granulosa cells, where LHCGR mediates a different pattern of signaling cascades, depending on the natural ligand. This finding is relevant for gonadotropin quantification used in the official pharmacopoeia, which are based on murine, in vivo bioassay and rely on the evaluation of long-term, testosterone-dependent effects mediated by rodent receptor.

The Dual Role of PEDF in the Pathogenesis of OHSS: Negating Both Angiogenic and Inflammatory Pathways.

Ovarian hyperstimulation syndrome (OHSS) is a potentially life-threatening complication of assisted reproductive technologies. This complex syndrome is known to involve massive angiogenesis and inflammation. We have previously established the anti-angiogenic involvement of pigment epithelium-derived factor (PEDF) in the pathophysiology and treatment of OHSS. Evaluate the anti-inflammatory role of PEDF in OHSS. In vivo mouse OHSS model and in vitro cultures of granulosa cells. Changes in the expression of PEDF, IL-6, IL-8, and vascular endothelial growth factor (VEGF) were measured by quantitative PCR and ELISA; OHSS symptoms were recorded (body and ovarian weight gain and peritoneal vascular leakage quantified by the modified Miles's assay). Rat granulosa cell-line stimulated with lysophosphatidic acid (LPA), exhibited a significant increase in IL-6 expression, concomitantly with a decrease in PEDF level (P < .01). Co-stimulation with recombinant PEDF (rPEDF) decreased the expression of IL-6 significantly (P < .05). Furthermore, the expression of IL-6 and IL-8 increased in LPA-stimulated human primary granulosa cells (P < .01). Co-stimulation with rPEDF decreased the expression of LPA-induced IL-6 and IL-8 mRNA and protein by 4- and 2- to 5-fold, respectively. IL-8-stimulated human primary granulosa cells exhibited increased expression of VEGF mRNA; co-stimulation with hCG induced a significantly higher increase in the expression of VEGF mRNA (P < .001), which was counteracted by rPEDF. Subcutaneous injection of 0.5 mg/kg rPEDF to OHSS-induced mice reduced the increased expression of IL-6 in the ovary (P < .01) and alleviated the severity of all OHSS parameters. Our findings provide a framework that correlates down-regulation of OHSS symptoms caused by PEDF with both angiogenic and inflammatory pathways.

Pigment epithelium-derived factor regulation by human chorionic gonadotropin in granulosa cells.

Human chorionic gonadotropin (hCG) is a known trigger of ovarian hyperstimulation syndrome (OHSS), a potentially life-threatening complication of assisted reproduction. Administration of hCG results in the release of vascular endothelial growth factor (VEGF) from the ovary. We have previously shown that expression of pigment epithelium-derived factor (PEDF) in granulosa cell line is regulated by hCG, reciprocally to VEGF, and that the PEDF-VEGF balance is impaired in OHSS. Our aim was to explore the signaling network by which hCG downregulates the expression of PEDF mRNA and protein in granulosa cells. We applied specific chemical inhibitors and stimuli to human primary granulosa cells and rat granulosa cell line. We found that PKA and protein kinase C, as well as EGFR, ERK1/2 and PI3K, participate in the signaling network. The finding that hCG-induced PEDF downregulation and VEGF upregulation are mediated by similar signaling cascades emphasizes the delicate regulation of ovarian angiogenesis.

TGF-β1 Up-Regulates Connective Tissue Growth Factor Expression in Human Granulosa Cells through Smad and ERK1/2 Signaling Pathways.

Connective tissue growth factor (CTGF), which is also called CCN2, is a secreted matricellular protein. CTGF regulates various important cellular functions by interacting with multiple molecules in the microenvironment. In the ovary, CTGF is mainly expressed in granulosa cells and involved in the regulation of follicular development, ovulation and luteinization. TGF-β1 has been shown to up-regulate CTGF expression in rat and hen granulosa cells. However, the underlying molecular mechanisms of this up-regulation remain undefined. More importantly, whether the stimulatory effect of TGF-β1 on CTGF expression can be observed in human granulosa cells remains unknown. In the present study, our results demonstrated that TGF-β1 treatment up-regulates CTGF expression in both immortalized human granulosa cells and primary human granulosa cells. Using a siRNA-mediated knockdown approach and a pharmacological inhibitor, we demonstrated that the inhibition of Smad2, Smad3 or ERK1/2 attenuates the TGF-β1-induced up-regulation of CTGF. This study provides important insights into the molecular mechanisms that mediate TGF-β1-up-regulated CTGF expression in human granulosa cells.