Oocyte-secreted factors strongly stimulate sFRP4 expression in human cumulus cells.

Secreted frizzled-related protein-4 (SFRP4) belongs to a family of soluble ovarian-expressed proteins that participate in female reproduction, particularly in rodents. In humans, SFRP4 is highly expressed in cumulus cells (CCs). However, the mechanisms that stimulate SFRP4 in CCs have not been examined. We hypothesise that oocyte-secreted factors such as growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) are involved in the regulation of SFRP4. Human CCs were collected from patients undergoing fertility treatments and treated with GDF9 or BMP15 or their combination in the presence of FSH or vehicle. FSH treatment significantly decreased SFRP4 mRNA levels when compared with nontreated cells. However, SFRP4 mRNA levels were increased significantly by GDF9 plus BMP15 in a concentration-dependent manner in the presence or absence of FSH. The combination of GDF9 plus BMP15 also increased SFRP4 protein levels and decreased the activity of the ß-catenin/T cell factor-responsive promoter significantly. GDF9 plus BMP15 inhibited steroidogenic acute regulatory protein and LH/hCG receptor stimulation by FSH, while treatment with SFRP4 blocked the stimulatory effect of FSH on these genes. The evidence demonstrates that GDF9 and BMP15 act in coordination to stimulate SFRP4 expression and suggests that SFRP4 mediates the anti-luteinising effects of the oocyte in human CCs.

Sp1 regulates steroidogenic genes and LHCGR expression in primary human luteinized granulosa cells.

Luteinizing hormone and human chorionic gonadotropin (hCG) bind to the luteinizing hormone/chorionic gonadotropin receptor (LHCGR). LHCGR is required to maintain corpus luteum function but the mechanisms involved in the regulation of LHCGR in human luteal cells remain incompletely understood. This study aimed to characterize the expression of LHCGR mRNA in primary human luteinized granulosa cells (hLGCs) obtained from patients undergoing in vitro fertilization and to correlate LHCGR expression with the response of hLGCs to hCG by assessing the expression of genes known to be markers of hCG actions. The results show that LHCGR expression is low in freshly isolated cells but recovers rapidly in culture and that hCG maintains LHCGR expression, suggesting a positive feedback loop. The activity of a LHCGR-LUC reporter increased in cells treated with hCG but not with follicle-stimulating hormone. Treatment with hCG also stimulated the expression of genes involved in steroidogenesis in a time-dependent manner. LHCGR promoter expression was found to be regulated by SP1, which we show is highly expressed in hLGCs. Moreover, SP1 inhibition prevented the stimulation of steroidogenic genes and the increase in LHCGR-LUC reporter activity by hCG. Finally, we provide evidence that a complex formed by SP1 and GATA4 may play a role in the maintenance of LHCGR expression. This report reveals the mechanisms involved in the regulation of the LHCGR and provides experimental data demonstrating that the proximal region of the LHCGR promoter is sufficient to drive the expression of this gene in primary hLGCs.

Oocyte-Secreted Factors Synergize With FSH to Promote Aromatase Expression in Primary Human Cumulus Cells.

CONTEXT: The role of growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) on aromatase regulation is poorly understood in humans. OBJECTIVE: Determine GDF9 and BMP15 effects on FSH stimulation of estradiol production in primary human cumulus granulosa cells (GCs). We hypothesized that the combination of GDF9 and BMP15 potentiates FSH-induced aromatase expression. DESIGN: Primary human cumulus GCs in culture. SETTING: University infertility center. PATIENTS OR OTHER PARTICIPANTS: GCs of 60 women undergoing in vitro fertilization were collected. INTERVENTIONS: Cells were treated with GDF9 and/or BMP15 (GB) in the presence or absence of FSH, dibutyryl cAMP, or SMAD inhibitors. MAIN OUTCOME MEASURES: Promoter activity, mRNA, protein, and estradiol levels were quantified. RESULTS: FSH and GB treatment increased CYP19A1 promoter activity, mRNA, and protein levels as well as estradiol when compared with cells treated with FSH only. GB treatment potentiated cAMP stimulation of aromatase and IGF2 stimulation by FSH. GB effects were inhibited by SMAD3 inhibitors and IGF1 receptor inhibitors. GB, but not FSH, stimulates SMAD3 phosphorylation. CONCLUSION: The combination of GDF9 and BMP15 potently stimulates the effect of FSH and cAMP on CYP19a1 promoter activity and mRNA/protein levels. These effects translate into an increase in estradiol production. This potentiation seems to occur through activation of the SMAD2/3 and SMAD3 signaling pathway and involves, at least in part, the effect of the IGF system.

Regulation of AMH by oocyte-specific growth factors in human primary cumulus cells.

The regulation of AMH production by follicular cells is poorly understood. The purpose of this study was to determine the role of the oocyte-secreted factors, growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15), on AMH production in primary human cumulus cells. Cumulus cells from IVF patients were cultured with a combination of GDF9, BMP15, recombinant FSH and specific signaling inhibitors. Stimulation with GDF9 or BMP15 separately had no significant effect on AMH mRNA levels. In contrast, simultaneous stimulation with GDF9 and BMP15 (G + B) resulted in a significant increase in AMH mRNA expression. Increasing concentration of G + B (0.6, 2.5, 5 and 10 ng/mL) stimulated AMH in a dose-dependent manner, showing a maximal effect at 5 ng/mL. Western blot analyses revealed an average 16-fold increase in AMH protein levels in cells treated with G + B when compared to controls. FSH co-treatment decreased the stimulation of AMH expression by G + B. The stimulatory effect of G + B on the expression of AMH was significantly decreased by inhibitors of the SMAD2/3 signaling pathway. These findings show for the first time that AMH production is regulated by oocyte-secreted factors in primary human cumulus cells. Moreover, our novel findings establish that the combination of GDF9 + BMP15 potently stimulates AMH expression.

Genome-wide interactions between FSH and insulin-like growth factors in the regulation of human granulosa cell differentiation.

Study question: Is the genome-wide response of human cumulus cells to FSH and insulin-like growth factors (IGFs) comparable to the response observed in undifferentiated granulosa cells (GCs)? Summary answer: FSH actions in human cumulus cells mimic those observed in preantral undifferentiated GCs from laboratory animals, and approximately half of the regulated genes are dependent on the simultaneous activation of the IGF1 receptor (IGF1R). What is known already: Animal studies have shown that FSH and the IGFs system are required for follicle growth and maturation. In humans, IGF levels in the follicular fluid correlate with patients' responses to IVF protocols. The main targets of FSH and IGFs in the ovary are the GCs; however, the genomic mechanisms involved in the response of GCs to these hormones are unknown. Study design, size, duration: Human cumulus cells isolated from IVF patients were cultured for 48 h in serum-free media in the presence of vehicle, FSH, IGF1R inhibitor or their combination. Participants/materials, setting, methods: Discarded cumulus cells were donated to research by reproductive-aged women undergoing IVF due to non-ovarian etiologies of infertility at a university-affiliated clinic. The effect of FSH and/or IGF1R inhibition on cumulus cell function was evaluated using Affymetrix microarrays, quantitative PCR, western blot, promoter assays and hormone level measurements. Main results and the role of chance: The findings demonstrate that human cumulus cells from IVF patients respond to FSH with the expression of genes known to be markers of the preantral to preovulatory differentiation of GCs. These results also demonstrate that ~50% of FSH-regulated genes require IGF1R activity and suggest that several aspects of follicle growth are coordinately regulated by FSH and IGFs in humans. This novel approach will allow for future mechanistic and molecular studies on the regulation of human follicle maturation. Large scale data: Data set can be accessed at Gene Expression Omnibus number GSE86427. Limitations, reasons for caution: Experiments were performed using primary human cumulus cells. This may not represent the response of intact follicles. Wider implications of the findings: Understanding the mechanisms involved in the regulation of GC differentiation by FSH and IGF in humans will contribute to improving treatments for infertility. Study funding/competing interest(s): The project was financed by the National Instituted of Health grant number R56HD086054 and R01HD057110 (C.S.). The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript. We have no competing interests to declare.

FSH Regulates IGF-2 Expression in Human Granulosa Cells in an AKT-Dependent Manner.

CONTEXT: IGF-2 is highly expressed in the granulosa cells of human dominant ovarian follicles; however, little is known about the regulation of the IGF-2 gene or the interaction of IGF-2 and FSH during follicle development. OBJECTIVE: To examine the mechanisms involved in the regulation of the IGF-2 gene by FSH and the interplay between FSH and IGF-2 during granulosa cell differentiation. Design, Setting, Patients, and Interventions: Cumulus granulosa cells were separated from cumulus-oocyte complexes isolated from the follicular aspirates of in vitro fertilization patients and cultured for in vitro studies. MAIN OUTCOME: Protein and mRNA levels of IGF-2 and CYP19A1 (aromatase) were quantified using Western blot and quantitative real-time PCR. IGF-2 promoter-specific activation was determined by the amplification of alternative exons by PCR. Cell proliferation was assessed after treatment with FSH and/or IGF-2. RESULTS: FSH significantly enhanced IGF-2 expression after 8 hours of treatment and at low doses (1 ng/mL). Reciprocally, IGF-2 synergized with FSH to increase cell proliferation and the expression of CYP19A1. When IGF-2 activity was blocked, FSH was no longer able to stimulate CYP19A1 expression. Determination of IGF-2 promoter usage in human cumulus cells showed that the IGF-2 gene is driven by promoters P3 and P4. However, FSH exclusively increased P3 promoter-derived transcripts. Moreover, the FSH-induced stimulation of P3-driven IGF-2 transcripts was blocked by cotreatment with inhibitors of AKT or IGF-1 receptor (IGF-1R). The inhibitory effect of the IGF-1R inhibitor on FSH-induced IGF-2 mRNA accumulation was reversed by overexpression of a constitutively active AKT construct. CONCLUSIONS: FSH is a potent enhancer of IGF-2 expression in human granulosa cells. In return, IGF-2 activation of the IGF-1R and AKT is required for FSH to stimulate CYP19A1 expression and proliferation of granulosa cells. These findings suggest a positive loop interaction between FSH and IGF-2 that is critical for human granulosa cell proliferation and differentiation.

IGF1R signaling is necessary for FSH-induced activation of AKT and differentiation of human Cumulus granulosa cells.

CONTEXT: FSH is routinely administered to in vitro fertilization patients to induce follicle maturation. During this process, granulosa cells differentiate and acquire specific functional characteristics that are required to coordinate ovulation and oocyte maturation. OBJECTIVE: The objective of the study was to gain insight into the molecular mechanisms regulating human granulosa cell differentiation. Design, Setting, Patients, and Interventions: Cumulus and mural granulosa cells were isolated from the follicular aspirates of in vitro fertilization patients and analyzed immediately or cultured in serum-free media in the presence of FSH, IGFs, or an inhibitor of type I IGF receptor (IGF1R) activity. MAIN OUTCOME: We quantified the mRNA and protein levels of steroidogenic enzymes, components of the IGF system, and gonadotropin receptors; measured 17ß-estradiol levels; and examined the activation of intracellular signaling pathways to assess the granulosa cell differentiation as well as the FSH and IGF actions in both cumulus and mural cells. RESULTS: In freshly isolated cells, LH receptor (Lhr) and steroidogenic acute regulator (Star) were expressed at lower levels in cumulus than mural cells, whereas FSH receptor (Fshr) and anti-Müllerian hormone (Amh) were expressed at higher levels in cumulus than mural cells. In vitro, the expression of Igf2, the differentiation markers Lhr, Star, and Cyp19a1 (aromatase) as well as 17ß-estradiol production remained low in untreated cumulus cells but increased significantly after FSH treatment. Strikingly, this stimulatory effect of FSH was abolished by the inhibition of IGF1R activity. FSH-induced activation of v-akt murine thymoma viral oncogene homolog 3 (AKT) required IGF1R activity, and overexpression of constitutively active AKT rescued the induction of differentiation markers and 17ß-estradiol production by FSH in the presence of the IGF1R inhibitor. CONCLUSIONS: The cumulus cell response to FSH resembles the differentiation of preantral to preovulatory granulosa cells. This differentiation program requires IGF1R activity and subsequent AKT activation.

In vitro fertilization pregnancy rates in levothyroxine-treated women with hypothyroidism compared to women without thyroid dysfunction disorders.

BACKGROUND: Untreated hypothyroidism can lead to ovulatory dysfunction resulting in oligo-amenorrhea. Treatment with levothyroxine can reverse such dysfunction and thus should improve fertility. The purpose of this retrospective study was to assess whether in vitro fertilization (IVF) pregnancy rates differ in levothyroxine-treated women with hypothyroidism compared to women without thyroid dysfunction/disorders. METHODS: Treated hypothyroid and euthyroid women undergoing IVF at an academic IVF center were studied after Institutional Review Board approval. Women with hypothyroidism were treated with levothyroxine 0.025-0.15 mg/day for at least 3 months to maintain baseline thyrotropin (TSH) levels of 0.35-4.0 µU/mL prior to commencing IVF treatment (HYPO-Rx group). Causes of infertility were similar in both groups with the exception of male factor, which was more common in the HYPO-Rx group. The main outcomes studied were implantation rate, clinical pregnancy rate, clinical miscarriage rate, and live birth rate. RESULTS: We reviewed the first IVF retrieval cycle performed on 240 women aged 37 years or less during the period January 2003 to December 2007. Women with treated hypothyroidism (n=21) had significantly less implantation, clinical pregnancy, and live birth rates than euthyroid women (n=219). CONCLUSIONS: We conclude that, despite levothyroxine treatment, women with hypothyroidism have a significantly decreased chance of achieving a pregnancy following IVF compared to euthyroid patients. A larger prospective study is necessary to assess confounding variables, confirm these findings, and determine the optimal level of TSH prior to and during controlled ovarian hyperstimulation for IVF.