DNA microarray analysis of the expression profiles of luteinized granulosa cells as a function of ovarian reserve

Diminished ovarian reserve causes adverse ART outcomes attributed to effects on oxygen metabolism function in cumulus cells

BACKGROUND

Declining oocyte quality in women with advanced age has been a major impediment to assisted reproductive treatments' (ART) success rate. However, aging is often accompanied by a diminished ovarian reserve (DOR). Cumulus cells (CCs) are known to play an important role in the development and maturation of oocytes, and the quality of CCs actually reflects the quality of the oocyte. In this study, CCs were used to investigate the real reasons for the decline in oocyte quality in older women.

METHODS

Ninety-nine CC samples were subdivided into 4 different groups according to the different age and ovarian reserve status. Other than clinical ART results, transcriptional expression profiles were performed in CCs to detect the differences.

RESULTS

The results were that DOR, no matter in young or advanced age group, was found to be significantly associated with adverse ART outcomes. Of note, there were no statistically significant changes in ART outcomes in the group at advanced age with normal ovarian reserve (NOR), compared to the young with NOR. DOR induced a series of transcriptional variations in CCs commonly enriched in oxygen metabolism.

CONCLUSION

Our results revealed that the ART outcomes in advanced patients were attributable to the DOR. The oxygen metabolic changes may interfere with CCs' function of supporting oocytes. This study can provide guidance for ART practice that not age but ovarian reserve status is the main predictor for ART outcomes, and ovarian reserve status should be timely assessed when the clinical manifestations are still mild in elderly women.

Using bioinformatics and metabolomics to identify altered granulosa cells in patients with diminished ovarian reserve

Background

During fertility treatment, diminished ovarian reserve (DOR) is a challenge that can seriously affect a patient's reproductive potential. However, the pathogenesis of DOR is still unclear and its treatment options are limited. This study aimed to explore DOR's molecular mechanisms.

Methods

We used R software to analyze the mRNA microarray dataset E-MTAB-391 downloaded from ArrayExpress, screen for differentially expressed genes (DEGs), and perform functional enrichment analyses. We also constructed the protein-protein interaction (PPI) and miRNA-mRNA networks. Ovarian granulosa cells (GCs) from women with DOR and the control group were collected to perform untargeted metabolomics analyses. Additionally, small molecule drugs were identified using the Connectivity Map database.

Results

We ultimately identified 138 DEGs. Our gene ontology (GO) analysis indicated that DEGs were mainly enriched in cytokine and steroid biosynthetic processes. According to the Kyoto Encyclopedia of Genes and Genomes (KEGG), the DEGs were mainly enriched in the AGE (advanced glycation end-product)-RAGE (receptor for AGE) signaling pathway in diabetic complications and steroid biosynthesis. In the PPI network, we determined that JUN, EGR1, HMGCR, ATF3, and SQLE were hub genes that may be involved in steroid biosynthesis and inflammation. miRNAs also played a role in DOR development by regulating target genes. We validated the differences in steroid metabolism across GCs using liquid chromatography-tandem mass spectrometry (LC-MS/MS). We selected 31 small molecules with potentially positive or negative influences on DOR development.

Conclusion

We found that steroidogenesis and inflammation played critical roles in DOR development, and our results provide promising insights for predicting and treating DOR.

CD36- and obesity-associated granulosa cells dysfunction

Emerging evidence indicates that obesity impairs granulosa cell (GC) function, but the underlying mechanisms remain unclear. Gene expression profiles in GC of non-polycystic ovary syndrome (PCOS) obese (NPO), PCOS obese (PO), PCOS normal weight (PN) and non-PCOS normal weight (NPN) patients were analysed by microarray analysis. Compared with the NPN group, there were 16, 545 and 416 differently expressed genes in the NPO, PO and PN groups respectively. CD36 was the only intersecting gene, with greater than two fold changes in expression between the NPO versus NPN and PO versus NPN comparisons, and was not present in the PN versus NPN comparison. In addition, levels of CD36 protein were higher in GC from obese than normal weight patients. Furthermore, CD36 overexpression in a GC line inhibited cell proliferation, as determined by the cell counting kit-8 (CCK8) test, promoted cell apoptosis, as determined by flow cytometry, and inhibited the secretion of oestradiol by depositing triglyceride in cells and increasing cellular lipid peroxide levels. These adverse effects were reduced by sulfo-N-succinimidyloleate, a specific inhibitor of CD36. Together, the findings of this study suggest that obesity with and without PCOS should be regarded as separate entities, and that CD36 overexpression in GC of obese patients is one of the mechanisms by which obesity impairs GC function.

Gene expression profiles of human granulosa cells treated with bioequivalent doses of corifollitropin alfa (CFA) or recombinant human follicle-stimulating hormone (recFSH)

Using recombinant DNA technologies, a chimeric gene containing the coding sequences of follicle stimulating hormone (FSH) β-subunit and C-terminal peptide of the human chorionic gonadotrophin (hCG) β-subunit have been designed to generate a new gonadotrophin named corifollitropin alfa (CFA). CFA has longer elimination half-life and slower rate of absorption compared with FSH, which makes CFA a long-acting hormone employed as a substitute of the recombinant FSH (recFSH) in the controlled ovarian stimulation (COS). The purpose of this study is to compare the gene expression profiles elicited by bioequivalent doses of CFA or recFSH in primary cultures of human granulosa cells (hGCs). Gonadotrophins exert their functions by binding FSH receptors (FSHRs), activating signaling pathways that increase the cyclic adenosine monophosphate (cAMP) intracellular content. Bioequivalence has been defined as the dose/duration of gonadotrophin treatment able to promote the same amount of intracellular cAMP. hGCs were treated with different doses of either gonadotrophin and the cAMP was measured after different incubation times to establish the bioequivalence. Results obtained by comparing the bioequivalent treatments, showed that CFA is more effective than recFSH in inducing aromatase gene expression after 6 and 24 h from the initial stimulation in agreement with its long-acting characteristic.

Granulosa cell biomarkers to predict pregnancy in ART: pieces to solve the puzzle

Cumulus and mural granulosa cells of the ovarian follicle surround and interact with the developing oocyte. These follicular cells reflect the oocyte's overall health and may indicate subsequent developmental competence of embryos. Biomarkers of granulosa cells associated with individual oocytes could potentially be used in assisted reproduction to indicate which embryos have the best chance of implanting in the uterus and completing gestation. In this review, we have performed a comprehensive assessment of the recent literature for human cumulus and mural granulosa cell mRNA biomarkers as they relate to pregnancy and live birth. A critical discussion of variables affecting granulosa gene expression profiles for in vitro fertilization patients, including patient demographics and ovarian stimulation regimens, is presented. Although studies with microarray data were evaluated, this synopsis focuses on expressed genes that have been validated by quantitative RT-PCR. Furthermore, we summarize the current published data that support or refute identified granulosa expressed genes as potential biomarkers of embryos that give rise to ongoing pregnancy and live birth. Finally, we review studies that offer predictive models for embryo selection for uterine transfer based on biomarkers that show differential gene expression.

Ovarian ageing: the role of mitochondria in oocytes and follicles

BACKGROUND

There is a great inter-individual variability of ovarian ageing, and almost 20% of patients consulting for infertility show signs of premature ovarian ageing. This feature, taken together with delayed childbearing in modern society, leads to the emergence of age-related ovarian dysfunction concomitantly with the desire for pregnancy. Assisted reproductive technology is frequently inefficacious in cases of ovarian ageing, thus raising the economic, medical and societal costs of the procedures.

OBJECTIVE AND RATIONAL

Ovarian ageing is characterized by quantitative and qualitative alteration of the ovarian oocyte reserve. Mitochondria play a central role in follicular atresia and could be the main target of the ooplasmic factors determining oocyte quality adversely affected by ageing. Indeed, the oocyte is the richest cell of the body in mitochondria and depends largely on these organelles to acquire competence for fertilization and early embryonic development. Moreover, the oocyte ensures the uniparental transmission and stability of the mitochondrial genome across the generations. This review focuses on the role played by mitochondria in ovarian ageing and on the possible consequences over the generations.

SEARCH METHODS

PubMed was used to search the MEDLINE database for peer-reviewed original articles and reviews concerning mitochondria and ovarian ageing, in animal and human species. Searches were performed using keywords belonging to three groups: 'mitochondria' or 'mitochondrial DNA'; 'ovarian reserve', 'oocyte', 'ovary' or 'cumulus cells'; and 'ageing' or 'ovarian ageing'. These keywords were combined with other search phrases relevant to the topic. References from these articles were used to obtain additional articles.

OUTCOMES

There is a close relationship, in mammalian models and humans, between mitochondria and the decline of oocyte quality with ageing. Qualitatively, ageing-related mitochondrial (mt) DNA instability, which leads to the accumulation of mtDNA mutations in the oocyte, plays a key role in the deterioration of oocyte quality in terms of competence and of the risk of transmitting mitochondrial abnormalities to the offspring. In contrast, some mtDNA haplogroups are protective against the decline of ovarian reserve. Quantitatively, mitochondrial biogenesis is crucial during oogenesis for constituting a mitochondrial pool sufficiently large to allow normal early embryonic development and to avoid the untimely activation of mitochondrial biogenesis. Ovarian ageing also seriously affects the dynamic nature of mitochondrial biogenesis in the surrounding granulosa cells that may provide interesting alternative biomarkers of oocyte quality.

WIDER IMPLICATIONS

A fuller understanding of the involvement of mitochondria in cases of infertility linked to ovarian ageing would contribute to a better management of the disorder in the future.

Relationship between diminished ovarian reserve and mitochondrial biogenesis in cumulus cells

STUDY QUESTION

What part do mitochondria play in cases of diminished ovarian reserve (DOR)?

SUMMARY ANSWER

Mitochondrial biogenesis in cumulus cells may be linked with impaired oocyte competence in patients with DOR.

WHAT IS KNOWN ALREADY

DOR, one of the causes of infertility even in young women, is characterized by the depletion of the ovarian pool associated with a decline in oocyte competence. Mitochondria, which play a role in oocyte quality, could be involved in the pathogenesis of DOR. The study of cumulus cells offers an interesting non-invasive approach for evaluating oocyte quality and the metabolic processes on which it depends. If mitochondrial dysfunction is involved in DOR, it is likely to have an impact on the functioning of cumulus cells.

STUDY DESIGN, SIZE, DURATION

This is an observational study of 74 immature oocyte-cumulus complexes retrieved from 47 women undergoing in vitro fertilization with intracytoplasmic sperm injection at the University Hospital of Angers, France, from March 2013 to March 2014. The women were divided into two groups: one group included 26 women with DOR, and the other, which included 21 women with a normal ovarian reserve (NOR), served as a control group.

PARTICIPANTS/MATERIALS, SETTINGS, METHODS

The oocyte mitochondrial content and the average mitochondrial content of the cumulus cells were assessed by mitochondrial (mt)DNA quantification using a quantitative real-time PCR technique. Microfluidic-based quantitative RT-PCR assays were used to quantify the expression of 13 genes involved in mitochondrial functions such as apoptosis and antioxidant activity or in mitochondrial biogenesis. We used orthogonal partial least-squares discriminant analysis (OPLS-DA) to distinguish between the DOR group and the NOR group of patients, and an OPLS model to predict the value of the oocyte mtDNA content that could be used as a critical marker of oocyte quality.

MAIN RESULTS AND THE ROLE OF CHANCE

The OPLS-DA model showed a good predictive capability (Q2 = 0.543). Using the variable importance in projection (VIP) metric we found three mitochondrial variables distinguishing the DOR group from the NOR group of patients, i.e. the oocyte mtDNA content (VIP = 0.92), the cumulus cell mtDNA content (VIP = 0.95) and the expression in cumulus cells of peroxisome proliferator-activated receptor γ coactivator 1 alpha (PPARGC-1A) (VIP = 1.10), all of which were lower in the DOR group than in the NOR group of patients. The OPLS model was able to satisfactorily predict the oocyte mtDNA content in only the NOR group of patients (Q2 = 0.506). We found four new variables positively linked to the oocyte mitochondrial mass, i.e. the cumulus cell mtDNA content (VIP = 1.19), and the expression in cumulus cells of three factors of mitochondrial biogenesis: polymerase gamma (POLG) (VIP = 2.13), optic atrophy 1 (OPA1) (VIP = 1.89) and the transcription factor associated with mitochondria (TFAM) (VIP = 1.32).

LIMITATIONS, REASONS OF CAUTION

This is a descriptive study. Because of ethical concerns in human clinical practice, this study has been performed only on immature oocytes and corresponding cumulus cells, which are usually discarded during in vitro fertilization procedures.

WIDER IMPLICATIONS OF THE FINDINGS

Cumulus cells may govern mitochondrial biogenesis, creating an adequate oocyte mitochondrial pool to promote embryonic development. The alteration of this process in patients with DOR may account for the impairment of oocyte quality. This suggests that some mitochondrial characteristics of cumulus cells may serve as indicators of oocyte competence and that oocyte quality may be improved by products enhancing mitochondrial biogenesis.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by a grant from the University Hospital of Angers, France: 'Appel d'offre interne à la recherche 2014'.

TRIAL REGISTRATION NUMBER

N/A.

Genetic associations with diminished ovarian reserve: a systematic review of the literature

PURPOSE

Diminished ovarian reserve (DOR) affects 10 % of women seeking fertility treatment. Although it is much more prevalent than premature ovarian failure, less is known about its etiology. The purpose of this article is to review the possible genetic causes of, and associations with, pathologic DOR.

METHODS

A systematic review was conducted using PubMed from 1966 through November 2013.

RESULTS

Twenty-one articles identified genes associated with DOR: one gene mutation (FMR1), three polymorphisms (GDF9, FSHR, and ESR1), and seven genes differentially expressed between women with DOR and controls (AMH, LHCGR, IGF1, IGF2, IGF1R, IGF2R and GREM1). Six candidate genes were discovered in mice, including Foxl2, Gdf9, Bmp15, Aire, Wnt4, and Gpr3. Two case reports of chromosomal translocations were also identified.

CONCLUSIONS

While the etiology of pathologic DOR is likely multifactorial, it is possible that many cases attributed to an idiopathic cause may have a genetic component. Larger studies are needed to expose the impact gene mutations, polymorphisms, and epigenetics have on pathologic DOR.

Bioengineering the ovarian follicle microenvironment

Chemo- and radiation therapies used to treat cancer can have the unintended effect of making patients infertile. Clinically established fertility preservation methods, such as egg and embryo cryopreservation, are not applicable to all patients, which has motivated the development of strategies that involve ovarian tissue removal and cryopreservation before the first sterilizing treatment. To restore fertility at a later date, the early-stage follicles present in the tissue must be matured to produce functional oocytes, a process that is not possible using existing cell culture technologies. This review describes the application of tissue engineering principles to promote ovarian follicle maturation and produce mature oocytes through either in vitro culture or transplantation. The design principles for these engineered systems are presented, along with identification of emerging opportunities in reproductive biology.

Gene expression profiling of granulosa cells from PCOS patients following varying doses of human chorionic gonadotropin

PURPOSE

Human chorionic gonadotrophin (hCG) has been used to induce ovulation and oocyte maturation. Although the most common dose of hCG used in IVF is 10,000 IU, there are reports that suggest 5,000 IU is sufficient to yield similar results. The objective of this study is to evaluate the dose dependent differences in gene expression of granulosa cells following various doses of hCG treatment.

METHODS

Patients with polycystic ovarian syndrome (PCOS) were stimulated for IVF treatment. The hCG injection was either withheld or given at 5,000 or 10,000 IU. Granulosa cells from the follicular fluids have been collected for RNA isolation and analyzed using Affymetrix genechip arrays.

RESULTS

Unsupervised hierarchical clustering based on whole gene expression revealed two distinct groups of patients in this experiment. All untreated patients were clustered together whereas hCG-treated patients separated to a different group regardless of the dose. A large number of the transcripts were similarly up- or down-regulated across both hCG doses (2229 and 1945 transcripts, respectively). However, we observed dose-dependent statistically significant differences in gene expression in only 15 transcripts.

CONCLUSIONS

Although hCG injection caused a major change in the gene expression profile of granulosa cells, 10,000 IU hCG resulted in minimal changes in the gene expression profiles of granulosa cells as compared with 5,000 IU. Thus, based on our results, we suggest the use of 10,000 IU hCG should be reconsidered in PCOS patients.

[Molecular characterization of corona radiata cells from patients with diminished ovarian reserve]

OBJECTIVES

Diminished ovarian reserve (DOR) is one of the causes of infertility. In this prospective study, gene expression profiling (GEP) of corona radiata cells (CRC) was performed to identify genes deregulated in DOR patients.

PATIENTS AND METHODS

Microarray-based GEP of CRC isolated from eight women undergoing IVF was performed to identify genes differentially expressed between patients with normal ovarian reserve and DOR patients. Microfluidic-based quantitative RT-PCR assay were used to validate selected transcripts on 40 independent patients.

RESULTS

Forty-eight transcripts were differentially expressed, including CXXC5 and FOXC1 down regulated in DOR, as well as CTGF, FSTL3, PTGS2 and SOCS2 up regulated in DOR. According to these transcripts, two DOR patients'subgroups (DOR Gr1 and Gr2) were identified. In DOR Gr2 patients, CITED2, CTGF, GAS-1, IRS2, PTGS2, SOCS2, VCAN were expressed at significantly higher levels, and CXXC5, FOXC1, GBP2 and ZMIZ1 at significantly lower level. Eleven of those genes are transcriptional targets of Estrogens and higher baseline oestradiol levels were observed in DOR Gr2 patients (P<0.006).

DISCUSSION AND CONCLUSION

Twelve genes deregulated in CRC of DOR patients were identified, which could be involved in DOR pathogenesis. The distinction of a particular subgroup of DOR patients suggests the possibility of deregulation of estrogen response genes.

Ovarian reserve status in young women is associated with altered gene expression in membrana granulosa cells

Diminished ovarian reserve (DOR) is a challenging diagnosis of infertility, as there are currently no tests to predict who may become affected with this condition, or at what age. We designed the present study to compare the gene expression profile of membrana granulosa cells from young women affected with DOR with those from egg donors of similar age and to determine if distinct genetic patterns could be identified to provide insight into the etiology of DOR. Young women with DOR were identified based on FSH level in conjunction with poor follicular development during an IVF cycle (n = 13). Egg donors with normal ovarian reserve (NOR) comprised the control group (n = 13). Granulosa cells were collected following retrieval, RNA was extracted and microarray analysis was conducted to evaluate genetic differences between the groups. Confirmatory studies were undertaken with quantitative RT-PCR (qRT-PCR). Multiple significant differences in gene expression were observed between the DOR patients and egg donors. Two genes linked with ovarian function, anti-Mullerian hormone (AMH) and luteinizing hormone receptor (LHCGR), were further analyzed with qRT-PCR in all patients. The average expression of AMH was significantly higher in egg donors (adjusted P-value = 0.01), and the average expression of LHCGR was significantly higher in DOR patients (adjusted P-value = 0.005). Expression levels for four additional genes, progesterone receptor membrane component 2 (PGRMC2), prostaglandin E receptor 3 (subtype EP3) (PTGER3), steroidogenic acute regulatory protein (StAR), and StAR-related lipid transfer domain containing 4 (StarD4), were validated in a group consisting of five NOR and five DOR patients. We conclude that gene expression analysis has substantial potential to determine which young women may be affected with DOR. More importantly, our analysis suggests that DOR patients fall into two distinct subgroups based on gene expression profiles, indicating that different mechanisms may be involved during development of this pathology.

Differential granulosa cell gene expression in young women with diminished ovarian reserve

OBJECTIVE

To investigate if a diagnosis of diminished ovarian reserve (DOR) is associated with a differential gene profile of ovarian granulosa cells (GCs) in infertile women undergoing in vitro fertilization (IVF).

DESIGN

Prospective Cohort Study.

SETTING

Academic IVF Program.

PATIENTS

Infertile women <38 years were prospectively enrolled into 2 groups: normal ovarian reserve (NOR, follicle-stimulating hormone [FSH] < 10 mIU/mL, n = 4) and DOR (FSH ≥ 10.0 mIU/mL, n = 4).

INTERVENTIONS

Cumulus (C) and mural (M) GCs were isolated at egg retrieval; messenger RNA was extracted and transcribed.

MAIN OUTCOME MEASURE(S)

Differential gene expression in cerebellar granule cells (CGCs) in the 2 groups was assessed by cDNA microarray. Microarray findings were validated by quantitative real-time polymerase chain reaction (qRTPCR) in CGCs and explored in multinucleated giant cells (MGCs).

RESULTS

Of the 1256 differentially regulated genes identified in CGCs of women with DOR, the insulin-like growth factor (IGF) family was a biologically relevant gene family of a priori interest. Downregulation of IGF1 and IGF2 ligands (-3.28- and -2.54-fold, respectively), and their receptors, (-3.53- and -1.32-fold downregulation of IGF1R and IGF2R, respectively) was identified in luteinized CGCs in women with DOR compared to those with NOR. Downregulation of both IGF1 and IGF 2 ligands (-4.35- and 3.89-fold, respectively) was furthermore observed in MGCs in women with DOR compared to those with NOR; no differences in the expression of respective receptors were however observed in MGCs in the 2 groups.

CONCLUSIONS

Components of the IGF gene family are downregulated in GCs of women with DOR. These findings maybe contributory to the reproductive compromise observed in women with DOR, and merit further exploration.

Dynamics of the transcriptome in the primate ovulatory follicle

Experiments were designed to evaluate changes in the transcriptome (mRNA levels) in the ovulatory, luteinizing follicle of rhesus monkeys, using a controlled ovulation model that permits analysis of the naturally selected, dominant follicle at specific intervals (0, 12, 24 and 36 h) after exposure to an ovulatory (exogenous hCG) stimulus during the menstrual cycle. Total RNA was prepared from individual follicles (n= 4-8/timepoint), with an aliquot used for microarray analysis (Affymetrix Rhesus Macaque Genome Array) and the remainder applied to quantitative real-time PCR (q-PCR) assays. The microarray data from individual samples distinctly clustered according to timepoints, and ovulated follicles displayed markedly different expression patterns from unruptured follicles at 36 h. Between timepoint comparisons revealed profound changes in mRNA expression profiles. The dynamic pattern of mRNA expression for steroidogenic enzymes (CYP17A, CYP19A, HSD3B2, HSD11B1 and HSD11B2), steroidogenic acute regulatory protein (StAR) and gonadotrophin receptors [LH/choriogonadotrophin receptor (LHCGR), FSH receptor (FSHR)] as determined by microarray analysis correlated precisely with those from blinded q-PCR assays. Patterns of mRNA expression for epidermal-growth-factor-like factors (amphiregulin, epiregulin) and processes [hyaluronan synthase 2 (HAS2), tumor necrosis factor alpha-induced protein 6 (TNFAIP6)] implicated in cumulus-oocyte maturation/expansion were also comparable between assays. Thus, several mRNAs displayed the expected expression pattern for purported theca (e.g. CYP17A), granulosa (CYP19A, FSHR), cumulus (HAS2, TNFAIP6) cell and surface epithelium (HSD11B)-related genes in the rodent/primate pre-ovulatory follicle. This database will be of great value in analyzing molecular and cellular pathways associated with periovulatory events in the primate follicle (e.g. follicle rupture, luteinization, inflammatory response and angiogenesis), and for identifying novel gene products controlling mammalian fertility.

Potential regulatory functions of microRNAs in the ovary

The interactions between ovarian germ and somatic cells and expression of several intraovarian autocrine/paracrine regulators are major contributing factors in the ovary. These intraovarian mediators regulate various ovarian cellular activities including cell growth, differentiation, and apoptosis, which are critical in follicular development. MicroRNAs (miRNAs) have emerged as key components of posttranscriptional gene expression. Recent evidence generated in mice implicates the regulatory function of miRNAs in oocyte maturation and ovarian follicular development. In the human, miRNAs may target specific gene expression in granulosa cells and participate in establishment and progression of ovarian cancer. Here, we review the currently available information on the expression and potential regulatory functions of miRNAs in the ovary under normal and pathologic conditions. Understanding the underlying mechanisms of how ovarian germ cell and somatic cell miRNAs are regulated and identifying their specific target genes and their functions may lead to the development of strategies to achieve target-specific gene regulation for the prevention and treatment of various ovarian disorders.

Regulation of granulosa and theca cell transcriptomes during ovarian antral follicle development

Coordinated interactions between ovarian granulosa and theca cells are required for female endocrine function and fertility. To elucidate these interactions the regulation of the granulosa and theca cell transcriptomes during bovine antral follicle development were investigated. Granulosa cells and theca cells were isolated from small (<5 mm), medium (5-10 mm), and large (>10 mm) antral bovine follicles. A microarray analysis of 24,000 bovine genes revealed that granulosa cells and theca cells each had gene sets specific to small, medium and large follicle cells. Transcripts regulated (i.e., minimally changed 1.5-fold) during antral follicle development for the granulosa cells involved 446 genes and for theca cells 248 genes. Only 28 regulated genes were common to both granulosa and theca cells. Regulated genes were functionally categorized with a focus on growth factors and cytokines expressed and regulated by the two cell types. Candidate regulatory growth factor proteins mediating both paracrine and autocrine cell-cell interactions include macrophage inflammatory protein (MIP1 beta), teratocarcinoma-derived growth factor 1 (TDGF1), stromal derived growth factor 1 (SDF1; i.e., CXCL12), growth differentiation factor 8 (GDF8), glia maturation factor gamma (GMFG), osteopontin (SPP1), angiopoietin 4 (ANGPT4), and chemokine ligands (CCL 2, 3, 5, and 8). The current study examined granulosa cell and theca cell regulated genes associated with bovine antral follicle development and identified candidate growth factors potentially involved in the regulation of cell-cell interactions required for ovarian function.

Declining ovarian reserve adversely influences granulosa cell viability

OBJECTIVE

To identify if declining ovarian reserve adversely influences granulosa cell (GC) parameters in patients undergoing IVF.

DESIGN

Prospective study.

SETTING

Academic IVF Center.

PATIENT(S)

Twenty-four women undergoing IVF.

INTERVENTION(S)

Mural and cumulus GCs were harvested (at time of egg retrieval).

MAIN OUTCOME MEASURE(S)

Influence of ovarian reserve, reflected by maximal basal FSH levels, on GC (cumulative, mural, and cumulus) counts and viability were investigated.

RESULT(S)

The FSH levels demonstrated an inverse correlation with cumulative and mural, but not cumulus, GC viability. Adverse influence of increasing FSH on cumulative GC viability was independent of patient's age. The GC counts were uninfluenced by ovarian reserve status. Neither GC count nor viability demonstrated any relationship with clinical pregnancy after IVF.

CONCLUSION(S)

We observed an adverse association between declining ovarian reserve and GC parameters. We believe these findings may partly explain the suboptimal reproductive performance in these women.

Analysis of microarray experiments of gene expression profiling

The study of gene expression profiling of cells and tissue has become a major tool for discovery in medicine. Microarray experiments allow description of genome-wide expression changes in health and disease. The results of such experiments are expected to change the methods employed in the diagnosis and prognosis of disease in obstetrics and gynecology. Moreover, an unbiased and systematic study of gene expression profiling should allow the establishment of a new taxonomy of disease for obstetric and gynecologic syndromes. Thus, a new era is emerging in which reproductive processes and disorders could be characterized using molecular tools and fingerprinting. The design, analysis, and interpretation of microarray experiments require specialized knowledge that is not part of the standard curriculum of our discipline. This article describes the types of studies that can be conducted with microarray experiments (class comparison, class prediction, class discovery). We discuss key issues pertaining to experimental design, data preprocessing, and gene selection methods. Common types of data representation are illustrated. Potential pitfalls in the interpretation of microarray experiments, as well as the strengths and limitations of this technology, are highlighted. This article is intended to assist clinicians in appraising the quality of the scientific evidence now reported in the obstetric and gynecologic literature.

Transcriptome analysis of FSH and FSH variant stimulation in granulosa cells from IVM patients reveals novel regulated genes

FSH is crucial for oocyte maturation and fertility and is the main component in infertility treatment in assisted reproduction. The granulosa cells expressing the FSH receptor interact with the oocyte and provide nourishing substrates controlling the oocyte maturation. Thus, transcriptome analysis of granulosa cells stimulated by FSH is of major importance in understanding the communication between oocytes and granulosa cells. In this study, gene expression profiles were assessed in human granulosa cells from normal cycling in vitro maturation (IVM) patients using oligonucleotide gene chips. Granulosa cells were stimulated for 2 h with either FSH or a previously generated glycosylated FSH variant (FSH1208) that exhibited increased in vivo activity because of prolonged half-life. The analysis identified 74 significantly FSH/FSH1208 regulated genes. Amongst these were well known FSH regulated genes as well as genes not previously described to be important in the FSH signalling pathway. These novel FSH regulated genes include transcription factors [cAMP responsive element modulator (CREM)/inducible cAMP early repressors (ICER), GATA 6, ZFN 361, Bcl11a, CITED1 and TCF 8] and other regulatory proteins and enzymes (IGF-BP3, syntaxin and PCK1) possibly important for oocyte/granulosa cell interaction and function. Array data were validated for 13 genes by northern blots or RT-PCR. Furthermore, no significant differences in gene regulation were detected between the two FSH analogs. This work uncovers novel data important for understanding the folliculogenesis. Furthermore, the results suggest that FSH1208 has a gene expression profile like FSH and thus, in the light of known prolonged in vivo activity, might be a candidate for improved infertility treatment.

Ovarian aging and menopause: current theories, hypotheses, and research models

Aging of the reproductive system has been studied in numerous vertebrate species. Although there are wide variations in reproductive strategies and hormone cycle components, many of the fundamental changes that occur during aging are similar. Evolutionary hypotheses attempt to explain why menopause occurs, whereas cellular hypotheses attempt to explain how it occurs. It is commonly believed that a disruption in the hypothalamic-pituitary-gonadal axis is responsible for the onset of menopause. Data exist to demonstrate that the first signs of menopause occur at the level of the brain or the ovary. Thus, finding an appropriate and representative animal model is especially important for the advancement of menopause research. In primates, there is a gradual decline in the function of the hypothalamic-pituitary-gonadal (HPG) axis ultimately resulting in irregularities in menstrual cycles and increasingly sporadic incidence of ovulation. Rodents also exhibit a progressive deterioration in HPG axis function; however, they also experience a period of constant estrus accompanied by intermittent ovulations, reduced progesterone levels, and elevated circulating estradiol levels. It is remarkable to observe that females of other classes also demonstrate deterioration in HPG axis function and ovarian failure. Comparisons of aging in various taxa provide insight into fundamental biological mechanisms of aging that could underlie reproductive decline.

Transcriptional profiling of granulosa cells from a patient with recurrent empty follicle syndrome

Empty follicle syndrome (EFS) is characterized by the absence of oocytes after apparently normal follicular development and the pathogenesis of this syndrome is not well characterized. The aim of this study was to analyse whole gene expression of granulosa cells (GC) from a patient with recurrent EFS by using Affymetrix GeneChip. A total of 160 genes were identified as being differentially expressed (by at least two-fold) between EFS GC and the control GC. Most of the differentially expressed genes were involved in cell growth and death. Among these were MAPK3, which plays an important role in the inhibition of apoptosis, was down-regulated 2.3-fold in EFS GC. Moreover, secretory phospholipase A2 and transforming growth factor receptor II, key regulators of cell death pathway, were down-regulated 3.54- and 2.82-fold respectively in EFS. Gene expression of granulosa cells from the EFS patient was significantly altered. The absence of the oocytes might be due to the increased apoptotic gene expression and the reduction of transcripts whose products are responsible for healthy follicular growth. Gene expression analyses might be a useful technique in identifying markers to follow a healthy follicular maturation and understanding the events that lead to EFS.

Mouse ovary developmental RNA and protein markers from gene expression profiling

To identify genes involved in morphogenetic events during mouse ovary development, we started with microarray analyses of whole organ RNA. Transcripts for 60% of the 15,000 gene NIA panel were detected, and about 2000 were differentially expressed in nascent newborn compared to adult ovary. Highly differentially expressed transcripts included noncoding RNAs and newly detected genes involved in transcription regulation and signal transduction. The phased pattern of newborn mouse ovary differentiation allowed us to (1) extend information on activity and stage specificity of cell type-specific genes; and (2) generate a list of candidate genes involved in primordial follicle formation, including podocalyxin (Podxl), PDGFR-beta, and a follistatin-domain-encoding gene Flst1. Oocyte-specific transcripts included many (e.g., Deltex2, Bicd2, and Zfp37) enriched in growing oocytes, as well as a novel family of untranslated RNA's (RLTR10) that is selectively expressed in early stage follicles. The results indicate that global expression profiling of whole organ RNA provides sensitive first-line information about ovarian histogenesis for which no in vitro cell models are currently available.

Alterations in the Ovarian Transcriptome During Primordial Follicle Assembly and Development1

The assembly of the developmentally arrested primordial follicle and subsequent transition to the primary follicle are poorly understood processes critical to ovarian biology. Abnormal primordial follicle development can lead to pathologies such as premature ovarian failure. The current study used a genome-wide expression profile to investigate primordial follicle assembly and development. Rat ovaries with predominantly unassembled, primordial, or primary follicles were obtained. RNA from these ovaries was hybridized to rat microarray gene chips, and the gene expression (i.e., ovarian transcriptome) was compared between the developmental stages. Analysis of the ovarian transcriptome demonstrated 148 genes up-regulated and 50 genes down-regulated between the unassembled and primordial follicle stages. Observations demonstrate 80 genes up-regulated and 44 genes down-regulated between the primordial and primary follicle stages. The analysis demonstrated 2332 genes common among the three developmental stages, 146 genes specific for the unassembled follicles, 94 genes specific for the primordial follicles, and 151 genes specific for the primary follicles. Steroidogenic genes are up-regulated between unassembled and primordial follicles, and then many are again down-regulated between primordial and primary follicles. The hormones inhibin and Mullerian inhibitory substance (MIS) display a similar pattern of expression with the highest levels of mRNA in the primordial follicles. Several novel unknown genes that had dramatic changes in expression during primordial follicle development were also identified. Gene families/clusters identified that were up-regulated from unassembled to primordial follicles include growth factors and signal transduction gene clusters, whereas a down-regulated gene family was the synaptonemal complex genes associated with meiosis. Gene families/clusters that were up-regulated between primordial and primary follicles included immune response genes, metabolic enzymes, and proteases, whereas down-regulated gene families include the globulin genes and some steroidogenic genes. The expression of several growth factors changed during primordial follicle development, including vascular endothelial growth factor and insulin-like growth factor II. Elucidation of how these changes in gene expression coordinate primordial follicle assembly and the primordial to primary follicle transition provides a better understanding of these critical biological processes and allows selection of candidate regulatory factors for further investigation.

Strategy for elucidating differentially expressed genes in leiomyomata identified by microarray technology

OBJECTIVE

cDNA microarray technology identifies genes that are differentially expressed between tissues. Our previous study identified several genes that might contribute to the fibroid phenotype. We therefore sought to confirm genes involved in three distinct signal transduction pathways.

DESIGN

Evaluation of differential mRNA and protein expression of Dlk, Frizzled-2, and CD-24 in fibroids compared with adjacent myometrium. University hospital.

PATIENT(S)

Five women undergoing medically indicated hysterectomy for symptomatic fibroids.

INTERVENTION(S)

Microarray analysis of up to 33000 genes, reverse transcriptase-polymerase chain reaction (RT-PCR), real-time RT-PCR, Western blot, and immunohistochemistry.

MAIN OUTCOME MEASURE(S)

Expression of mRNA transcripts and protein in fibroid compared with myometrium.A more extensive microarray confirmed differential expression of Frizzled-2 and CD-24 but did not confirm Dlk overexpression. RT-PCR and real-time PCR demonstrated equivalent Dlk mRNA expression between fibroid and myometrium (ratio, 1.02), a slight Frizzled-2 overexpression (ratio, 2.09), and robust CD-24 overexpression in fibroids (ratio, 12.35). Western blot and immunohistochemistry confirmed Frizzled-2 overexpression, but did not confirm Dlk overexpression.

CONCLUSION(S)

Microarray technology is the first phase of tissue evaluation, but changes in gene expression must be confirmed. Confirmed genes can then be used to generate hypotheses testing their involvement in fibroid development.