Hypomethylation of the LH/choriogonadotropin receptor promoter region is a potential mechanism underlying susceptibility to polycystic ovary syndrome

Assessment of the Effect of Leonurine Hydrochloride in a Mouse Model of PCOS by Gene Expression Profiling

Polycystic ovary syndrome (PCOS) is an endocrine disease commonly associated with metabolic disorders in females. Leonurine hydrochloride (Leo) plays an important role in regulating immunity, tumours, uterine smooth muscle, and ovarian function. However, the effect of Leo on PCOS has not been reported. Here, we used dehydroepiandrosterone to establish a mouse model of PCOS, and some mice were then treated with Leo by gavage. We found that Leo could improve the irregular oestros cycle of PCOS mice, reverse the significantly greater serum testosterone (T) and luteinising hormone (LH) levels, significantly reduce the follicle-stimulating hormone (FSH) level, and significantly increase the LH/FSH ratio of PCOS mice. Leo could also change the phenomenon of ovaries in PCOS mice presented with cystic follicular multiplication and a lacking corpus luteum. Transcriptome analysis identified 177 differentially expressed genes related to follicular development between the model and Leo groups. Notably, the cAMP signalling pathway, neuroactive ligand-receptor interactions, the calcium signalling pathway, the ovarian steroidogenesis pathway, and the Lhcgr, Star, Cyp11a, Hsd17b7, Camk2b, Calml4, and Phkg1 genes may be most related to improvements in hormone levels and the numbers of ovarian cystic follicles and corpora lutea in PCOS mice treated by Leo, which provides a reference for further study of the mechanism of Leo.

Epigallocatechin Gallate for the Treatment of Benign and Malignant Gynecological Diseases-Focus on Epigenetic Mechanisms

The most common malignant gynecologic diseases are cervical, uterine, ovarian, vaginal, and vulvar cancer. Among them, ovarian cancer causes more deaths than any other cancer of the female reproductive system. A great number of women suffer from endometriosis, uterine fibroids (UFs), adenomyosis, dysmenorrhea, and polycystic ovary syndrome (PCOS), which are widespread benign health problems causing troublesome and painful symptoms and significantly impairing the quality of life of affected women, and they are some of the main causes of infertility. In addition to the available surgical and pharmacological options, the effects of supporting standard treatment with naturally occurring compounds, mainly polyphenols, are being studied. Catechins are responsible for the majority of potential health benefits attributed to green tea consumption. Epigallocatechin gallate (EGCG) is considered a non-toxic, natural compound with potential anticancer properties. Antioxidant action is its most common function, but attention is also drawn to its participation in cell division inhibition, apoptosis stimulation and epigenetic regulation. In this narrative review, we describe the role of EGCG consumption in preventing the development of benign reproductive disorders such as UF, endometriosis, and PCOS, as well as malignant gynecologic conditions. We discuss possible epigenetic mechanisms that may be related to the action of EGCG.

DNA methylation associated with polycystic ovary syndrome: a systematic review

PURPOSE

Polycystic ovary syndrome (PCOS) is an endocrine metabolic disease that affects women of reproductive age and is one of the main causes of anovulatory infertility. However, the cause of PCOS is yet fully understood, and genetic factors play an important role in its etiology. In this study, we reviewed the main genes involved in the etiology of PCOS and the influence of DNA methylation, aiming to answer the study´s guiding question: 'What is the influence of DNA methylation on the main genes involved in PCOS?'.

METHODS

We used the MEDLINE database, and inclusion criteria (primary and original articles, written in English, found through our entry terms) and exclusion criteria (literature reviews and articles that used animals to perform the experiments and that focused in other epigenetics mechanism without being DNA methylation) were applied.

RESULTS

Twenty-three scientific articles, from a total of 43 articles read in full, were chosen for this study. Eighteen studies confirmed DNA methylation associated with PCOS.

CONCLUSION

The most relevant genes related to PCOS were INSR, LHCGR, and RAB5B, which may be epigenetically altered in DNA, with the first two genes hypomethylated and the last hypermethylated. The epigenetic changes presented in the genes related to PCOS or their promoters were only at the CpG sites.

Modulation of the Inflammatory Response in Polycystic Ovary Syndrome (PCOS)-Searching for Epigenetic Factors

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of reproductive age. Despite its incidence, the syndrome is poorly understood and remains underdiagnosed, and female patients are diagnosed with a delay. The heterogenous nature of this complex disorder results from the combined occurrence of genetic, environmental, endocrine, and behavioral factors. Primary clinical manifestations of PCOS are derived from the excess of androgens (anovulation, polycystic ovary morphology, lack of or scanty, irregular menstrual periods, acne and hirsutism), whereas the secondary manifestations include multiple metabolic, cardiovascular, and psychological disorders. Dietary and lifestyle factors play important roles in the development and course of PCOS, which suggests strong epigenetic and environmental influences. Many studies have shown a strong association between PCOS and chronic, low-grade inflammation both in the ovarian tissue and throughout the body. In the vast majority of PCOS patients, elevated values of inflammatory markers or their gene markers have been reported. Development of the vicious cycle of the chronic inflammatory state in PCOS is additionally stimulated by hyperinsulinemia and obesity. Changes in DNA methylation, histone acetylation and noncoding RNA levels are presented in this review in the context of oxidative stress, reactive oxygen species, and inflammatory signaling in PCOS. Epigenetic modulation of androgenic activity in response to inflammatory signaling is also discussed.

Epigenetics in the etiology and management of infertility

BACKGROUND

Epigenetic disruptions have been implicated in some cases of infertility and can serve as therapeutic targets. However, the involvement of epigenetics in infertility has not received adequate attention.

AIM

This study aimed to determine the epigenetic basis of infertility in order to enhance public knowledge.

METHODS

Relevant articles on the subject were collected from PubMed, RCA, Google Scholar, SpringerLink, and Scopus. The articles were pooled together and duplicates were removed using Endnote software.

RESULTS

Available information shows that epigenetic mechanisms, mainly DNA methylation, histone modification, and microRNA interference are necessary for normal gametogenesis and embryogenesis. As a result, epigenetic disruptions in genes that control gametogenesis and embryogenesis, such as DDX3X, ADH4, AZF, PLAG1, D1RAS3, CYGB, MEST, JMJD1A, KCNQ1, IGF2, H19, and MTHFR may result in infertility. Aberrant DNA methylation during genomic imprinting and parental epigenetic mark erasures, in particular, may affect the DNA epigenomes of sperm and oocytes, resulting in reproductive abnormalities. Histone epigenetic dysregulation during oocyte development and histone-protamine replacement in the sperm may also cause reproductive abnormalities. Furthermore, overexpression or repression of certain microRNAs embedded in the ovary, testis, embryo, as well as granulosa cells and oocytes may impair reproduction. Male infertility is characterized by spermatogenesis failure, which includes oligozoospermia, asthenozoospermia, and teratozoospermia, while female infertility is characterized by polycystic ovary syndrome. Some epigenetic modifications can be reversed by deactivating the regulatory enzymes, implying that epigenetic reprogramming could help treat infertility in some cases. For some disorders, epigenetic drugs are available, but none have been formulated for infertility.

CONCLUSION

Some cases of infertility have an epigenetic etiology and can be treated by reversing the same epigenetic mechanism that caused it. As a result, medical practitioners are urged to come up with epigenetic treatments for infertility that have an epigenetic cause.

Role of genomic DNA methylation in PCOS pathogenesis: a systematic review and meta-analysis involving case controlled clinical studies

PCOS is often associated with aberrant DNA methylation. Despite the advances in diagnostics and treatment of PCOS, the pathophysiological mechanism remain unknown. Several genes are epigenetically dysregulated in PCOS and associated with pathological consequences of PCOS and metabolic comorbidities, however the methylation status of specific genes and to what extent the genes are deregulated in terms of methylation pattern are unknown. This review aimed to analyse the existing data for specific genes and find conclusive evidence of their involvement in PCOS and associated risks. A comprehensive literature search was conducted in five electronic databases. The case-controlled clinical studies using both PCOS and healthy women and evaluating the methylation pattern without any treatment or intervention were included in the study. A random-effect model was used to extract the data for meta-analysis, and outcomes were expressed as standardized mean difference with a 95% CI. From 541 screened records, 41 studies were included in the review and 21 of them were used for meta-analysis of 20 genes. Meta-analysis revealed a significant global DNA hypomethylation in different tissues and peripheral blood of patients with PCOS compared to healthy controls. Specific gene methylation assessment revealed that genes associated with several functions were significantly hypomethylated and hypermethylated in patients with PCOS. This review provides conclusive evidence of epigenetic deregulation of specific genes in PCOS. These genes can potentially be used to develop diagnostic biomarkers or as targets for personalised therapy.

Evidence for TET-mediated DNA demethylation as an epigenetic alteration in cumulus granulosa cells of women with polycystic ovary syndrome

Peripheral and tissue-specific alterations in global DNA methylation (5mC) and hydroxymethylation (5hmC) profiles have been charted as biomarkers for disease prediction and as hallmarks of dysregulated localized gene networks. Global and gene-specific epigenetic alterations in the 5mC profiles have shown widespread implications in etiology of polycystic ovary syndrome (PCOS). However, there has been no study in PCOS that integrates the quantification of 5mC and 5hmC signatures alongside the expression levels of DNA methylating and demethylating enzymes as respective indicators of methylation and demethylation pathways. Having previously shown that the 5mC signatures are not greatly altered in PCOS, we assessed the global 5hmC levels in peripheral blood leukocytes (PBLs) and cumulus granulosa cells (CGCs) of 40 controls and 40 women with PCOS. This analysis revealed higher 5hmC levels in CGCs of PCOS women, indicating a more dominant demethylation pathway. Further, we assessed the transcript and protein expression levels of DNA demethylating and methylating enzymes, i.e. ten-eleven translocation methylcytosine dioxygenases (TET1, TET2, TET3) and DNA methyltransferases (DNMT1, DNMT3A and DNMT3B), respectively, in CGCs. The relative transcript and protein expression levels of all three TETs were found to be higher in women with PCOS; and the TET mRNA expression profiles were positively correlated with 5hmC levels in CGCs. Also, all three DNMT genes showed altered transcript expression in PCOS, although only the downregulated DNMT3A transcript was correlated with decreasing 5mC levels. At the protein level, the expression of DNMT1 (maintenance methylation enzyme) was higher, while that of DNMT3A (denovo methylation enzyme) was found to be lower in PCOS compared to controls. Overall, these results indicate that DNA methylation changes in CGCs of PCOS women may arise partly due to intrinsic alterations in the transcriptional regulation of TETs and DNMT3A.

DNA Methylation in Polycystic Ovary Syndrome：Emerging Evidence and Challenges

Polycystic ovary syndrome (PCOS) is a disease related to reproductive endocrine abnormalities in women of reproductive age, often accompanied by metabolic diseases such as hyperandrogenemia, insulin resistance and dyslipidemia. However, the etiology and mechanism of PCOS are still unclear. In recent years, more and more studies have found that epigenetic factors play an important role in PCOS. DNA methylation is the most widely studied epigenetic modification. At present, changes of DNA methylation have been found in serum, ovarian, hypothalamus, skeletal muscle, adipose tissue of PCOS patients, and these changes are closely related to insulin resistance, lipid metabolism and follicular development of PCOS. Although the current research on DNA methylation in PCOS is not in-depth, it indicated up a good direction for future research on the etiology and mechanism of PCOS. This review discussed the relationship between DNA methylation and PCOS. It is expected to help accelerate the application of DNA methylation in the diagnosis and treatment of PCOS.

MeCP2 duplication causes hyperandrogenism by upregulating LHCGR and downregulating RORα

Duplication of MECP2 (methyl-CpG-binding protein 2) gene causes a serious neurological and developmental disorder called MECP2 duplication syndrome (MDS), which is usually found in males. A previous clinical study reported that MDS patient has precocious puberty with hyperandrogenism, suggesting increased MeCP2 may cause male hyperandrogenism. Here we use an MDS mouse model and confirm that MECP2 duplication significantly upregulates androgen levels. We show for the first time that MeCP2 is highly expressed in the Leydig cells of testis, where androgen is synthesized. Mechanistically, MECP2 duplication increases androgen synthesis and decreases androgen to estrogen conversion through either the upregulation of luteinizing hormone receptor (LHCGR) in testis, as a result of MeCP2 binds to G-quadruplex structure of Lhcgr promoter and recruits the transcription activator CREB1 or the downregulation of the expression of aromatase in testis by binding the CpG island of Rorα, an upstream regulator of aromatase. Taken together, we demonstrate that MeCP2 plays an important role in androgen synthesis, supporting a novel non-CNS function of MeCP2 in the process of sex hormone synthesis.

Epigenetic inheritance of polycystic ovary syndrome - challenges and opportunities for treatment

Polycystic ovary syndrome (PCOS) is the main cause of female infertility worldwide and is associated with a substantially increased lifetime risk of comorbidities, including type 2 diabetes mellitus, psychiatric disorders and gynaecological cancers. Despite its high prevalence (~15%) and substantial economic burden, the aetiology of PCOS remains elusive. The genetic loci linked to PCOS so far account for only ~10% of its heritability, which is estimated at 70%. However, growing evidence suggests that altered epigenetic and developmental programming resulting from hormonal dysregulation of the maternal uterine environment contributes to the pathogenesis of PCOS. Male as well as female relatives of women with PCOS are also at an increased risk of developing PCOS-associated reproductive and metabolic disorders. Although PCOS phenotypes are highly heterogenous, hyperandrogenism is thought to be the principal driver of this condition. Current treatments for PCOS are suboptimal as they can only alleviate some of the symptoms; preventative and targeted treatments are sorely needed. This Review presents an overview of the current understanding of the aetiology of PCOS and focuses on the developmental origin and epigenetic inheritance of this syndrome.

Replication study and meta-analysis of selected genetic variants and polycystic ovary syndrome susceptibility in Asian population

PURPOSE

Polycystic ovary syndrome (PCOS) is a highly complex disorder influenced by genetic and environmental factors. Previous association studies have identified multiple PCOS-susceptible loci, but there is no consistent conclusion, which calls for further investigations.

METHODS

In the present case-control study, FSHR gene variants (rs2268361, rs6165, and rs6166), LHCGR gene variant (rs13405728), THADA gene variant (rs13429458), DENND1A gene variants (rs10818854 and rs2479106), and INSR gene variants (rs2059807 and rs1799817) were genotyped with Sanger sequencing in a total of 400 PCOS women and 480 healthy women.

RESULTS

After Bonferroni correction, our results showed that rs13405728, rs13429458, rs2479106, rs10818854, and rs2059807 were significantly associated with PCOS risk in Chinese women. To improve the statistical strength, a further meta-analysis in Asian population was conducted. Although rs6166 and rs1799817 were not associated with PCOS risk in the present study, they were identified to be strongly associated with PCOS risk in the pooled Koreans and Chinese respectively. No significant association with PCOS risk was consistently found for rs2268361 or rs6165. Moreover, the pooled results further confirmed the significant association with PCOS risk for rs13405728, rs13429458, rs2479106, rs10818854, and rs2059807.

CONCLUSIONS

Collectively, the rs6166, rs13405728, rs13429458, rs2479106, rs10818854, rs2059807, and rs1799817 may indeed be the genetic risk factors for PCOS in Asian population, which requires further investigation using larger independent sets of samples in different ethnic populations.

3 CpG methylation biomarkers for the diagnosis of polycystic ovary syndrome (PCOS) in blood

BACKGROUND

Polycystic ovary syndrome (PCOS) is a common endocrine disease in women that seriously interferes with the patient's metabolic and reproductive functions. The current diagnostic criteria for PCOS are expert-based and still disputed. Previous studies have identified changes in DNA methylation in peripheral blood of women with PCOS, but their diagnostic potential for PCOS remains to be studied.

OBJECTIVE

The present study aimed to identify potential methylation biomarkers for the diagnosis of PCOS in blood.

METHODS

Methylation profiles of peripheral blood were downloaded from a public database, Gene Expression Omnibus (GEO), of 30 PCOS patients (diagnosed with the revised 2003 Rotterdam consensus criteria), and 30 age-matched healthy women were recruited from the Centre of Reproductive Medicine, Linyi People's Hospital, Shandong, China. Weighted gene co-expression network analysis (WGCNA) was utilized to identify PCOS-related co-methylation CpG sites (co-MPs). Functional enrichment analysis was performed on the localized genes of PCOS-related co-MPs. The least absolute shrinkage and selection operator (LASSO) regression was used to screen CpG methylation signatures for PCOS diagnosis and receiver operating characteristic (ROC) analysis was conducted to evaluate their diagnostic accuracy, respectively. To assess the accuracy of the combination of the investigated indicators, multivariate ROC analysis was performed on the predicted probability values obtained using binary logistic regression on the methylation levels of selected CpGs together.

RESULTS

Seven co-methylation modules were obtained, most relevant to PCOS of which was the turquoise module, containing 194 co-MPs. The genes that these co-MPs located in were mainly associated with the immune-related pathway. According to LASSO regression, three Co-MPs (cg23464743, cg06834912, cg00103771) were identified as potential diagnostic biomarkers of PCOS. ROC analysis showed an AUC (area under the curve) of 0.7556 (sensitivity 60.0%, specificity 83.3%) for cg23464743, 0.7822 (sensitivity 70.0%, specificity 80.0%) for cg06834912, and 0.7611 (sensitivity 63.3%, specificity 83.3%) for cg00103771. The diagnostic accuracy of the combination of these 3 indicators presented to be higher than any single one of them, with an AUC of 0.8378 (sensitivity 73.3%, specificity 93.3%).

CONCLUSION

The combination of 3 CpG methylation signatures in blood was identified with a good diagnostic accuracy for PCOS, which may bring new insight into the development of PCOS diagnostic markers in the future.

Androgen-induced epigenetic modulations in the ovary

In recent years, androgens have emerged as critical regulators of female reproduction and women's health in general. While high levels of androgens in women are associated with polycystic ovary syndrome (PCOS), recent evidence suggests that a certain amount of direct androgen action through androgen receptor is also essential for normal ovarian function. Moreover, prenatal androgen exposure has been reported to cause developmental reprogramming of the fetus that manifests into adult pathologies, supporting the Developmental Origins of Health and Disease (DOHaD) hypothesis. Therefore, it has become imperative to understand the underlying mechanism of androgen actions and its downstream effects under normal and pathophysiological conditions. Over the years, there has been a lot of studies on androgen receptor function as a transcriptional regulator in the nucleus as well as androgen-induced rapid extra-nuclear signaling. Conversely, new evidence suggests that androgen actions may also be mediated through epigenetic modulation involving both the nuclear and extra-nuclear androgen signaling. This review focuses on androgen-induced epigenetic modifications in female reproduction, specifically in the ovary, and discusses emerging concepts, latest perceptions, and highlight the areas that need further investigation.

Polycystic Ovary Syndrome: the Epigenetics Behind the Disease

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders, affecting approximately 5-20% of women of reproductive age. PCOS is a multifactorial, complex, and heterogeneous disease, characterized by hyperandrogenism, ovulatory dysfunction, and polycystic ovaries, which may lead to impaired fertility. Besides the reproductive outcomes, multiple comorbidities, such as metabolic disturbances, insulin resistance, obesity, diabetes, and cardiovascular disease, are associated with PCOS. In addition to the clear genetic basis, epigenetic alterations may also play a central role in PCOS outcomes, as environmental and hormonal alterations directly affect clinical manifestations and PCOS development. Here, we highlighted the epigenetic modifications in the multiplicity of clinical manifestations, as well as environmental epigenetic disruptors, as intrauterine hormonal and metabolic alterations affecting embryo development and the adulthood lifestyle, which may contribute to PCOS development. Additionally, we also discussed the new approaches for future studies and potential epigenetic biomarkers for the treatment of associated comorbidities and improvement in quality of life of women with PCOS.

Polycystic Ovarian Syndrome Genetics and Epigenetics

Polycystic ovarian syndrome and its associated endocrine abnormalities comprise one of the most common metabolic spectrum disorders within the human race. Because of the variance in phenotypic expression among individuals and within family lineages, attention has been turned to genetic and epigenetic changes in which the root cause of the disorder may lie. Further understanding of DNA/histone methylation and microRNA patterns may help to improve the accuracy of diagnosis and lead to future treatment options.

Epigenetic Marks in Polycystic Ovary Syndrome

Polycystic Ovary Syndrome (PCOS) is a common endocrine and metabolic disorder that affects women in their reproductive age. Recent studies have shown that genes have an important role in the etiology of PCOS. However, the precise way in which these genes are transcriptionally and post-transcriptionally regulated is poorly understood. The aim of the present review is to provide updated information on miRNAs and DNA methylation as epigenetic marks of PCOS. The data presented here allow concluding that both microRNAs and DNA methylation can be considered as possible useful biomarkers when choosing the treatment for a specific PCOS phenotype and thus represent two important tools for the diagnosis and treatment of PCOS patients.

lnc-MAP3K13-7:1 Inhibits Ovarian GC Proliferation in PCOS via DNMT1 Downregulation-Mediated CDKN1A Promoter Hypomethylation

Polycystic ovary syndrome (PCOS) is an endocrine-related disease and global cause of infertility that is associated with abnormal folliculogenesis. Inhibited granulosa cell (GC) proliferation is recognized as a key factor that underlies aberrant follicle maturation. Many epigenetic landscape modifications have been characterized in PCOS patients. However, the epigenetic regulation pathways in follicular dysplasia are not completely understood. In this study, we reported a novel mechanism of DNA hypomethylation induced by long non-coding RNAs (lncRNAs) and its function in cell cycle progression. We observed that lnc-MAP3K13-7:1 was highly expressed in GCs from patients with PCOS, with concomitant global DNA hypomethylation, decreased DNA methyltransferase 1 (DNMT1) expression, and increased cyclin-dependent kinase inhibitor 1A (CDKN1A, p21) expression. In KGN cells, lnc-MAP3K13-7:1 overexpression resulted in cell cycle arrest in the G₀/G₁ phase, as well as the molecular inhibition and genetic silencing of DNMT1. Mechanistically, lnc-MAP3K13-7:1 inhibited DNMT1 expression by acting as a protein-binding scaffold and inducing ubiquitin-mediated DNMT1 protein degradation. Moreover, DNMT1-dependent CDKN1A promoter hypomethylation increased CDKN1A transcription, resulting in attenuated GC growth. Our work uncovered a novel and essential mechanism through which lnc-MAP3K13-7:1-dependent DNMT1 inhibition regulates CDKN1A/p21 expression and inhibits GC proliferation.

A Comprehensive Overview of Common Polymorphic Variants in Genes Related to Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is one of the most common endocrine-metabolic disorders in women of reproductive age. It is characterized by an increase in the biosynthesis of androgens, anovulation, and infertility. PCOS has been reported as a polygenic entity in which multiple single nucleotide polymorphisms (SNPs) are associated with the clinical features of the pathology. Herein, we describe the common polymorphic variants in genes related to PCOS, their role in its pathogenesis, and etiology. Whole-genome association studies have been focused on women from Asian and European populations. The most common genes associated with PCOS are DENND1A, THADA, FSHR, and LHCGR. However, other genes have been associated with PCOS such as AMH, AMHR2, ADIPOQ, FTO, HNF1A, CYP19, YAP1, HMGA2, RAB5B, SUOX, INSR, and TOX3. Nevertheless, the relationship between the biological functions of these genes and the development of the pathology is unclear. Studies in each gene in different populations do not always comply with a general pattern, so researching these variants is essential for better understanding of this polygenic syndrome. Future population studies should be carried out to evaluate biological processes, incidence rates, allelic and genotypic frequencies, and genetic susceptibility factors that predispose PCOS.

Role of Androgen Receptor for Reconsidering the "True" Polycystic Ovarian Morphology in PCOS

Purpose: Polycystic ovarian morphology (PCOM) is one of the key features of polycystic ovary syndrome (PCOS). The diagnosis of PCOM according to the Rotterdam criteria (≥12 antral follicles per ovary) is debated because of the high prevalence of PCOM in the general population. Androgen receptor (AR) is associated with the PCOS phenotype and might as well play a role during folliculogenesis. This study is aimed to investigate the expression of the AR in PCOS granulosa cells (GCs) and its relationship with the PCOM phenotype. Methods: 106 PCOS cases and 63 controls were included from the Center for Reproductive Medicine, Shandong University. The diagnosis of PCOS was following the Rotterdam criteria (2003). Total RNA was extracted from GCs retrieved from ovarian stimulation. The expression of AR was amplified by means of quantitative real-time polymerase chain reaction. Results: The AR expression was significantly decreased in PCOS cases, especially in the tPCOM subgroup (≥20 antral follicles per ovary). Correlation analyses showed that AR expression was significantly correlated with serum FSH levels in controls and non-tPCOM. In the tPCOM subgroup, the AR expression was significantly correlated with serum LH levels. Interestingly, the significance of these correlations gradually disappeared as the threshold of antral follicles increased above 24 for PCOM. Conclusions:AR was differently expressed in PCOS and especially in the tPCOM subtype. The correlation of AR expression with serum FSH and LH might be associated with the number of follicles in PCOM.

Key Relevance of Epigenetic Programming of Adiponectin Gene in Pathogenesis of Metabolic Disorders

Background & Objective::

Significant health and social burdens have been created by the growth of metabolic disorders like type 2 diabetes mellitus (T2DM), atherosclerosis, and non-alcoholic steatohepatitis, worldwide. The number of the affected population is as yet rising, and it is assessed that until 2030, 4−5 million individuals will acquire diabetes. A blend of environmental, genetic, epigenetic, and other factors, such as diet, are accountable for the initiation and progression of metabolic disorders. Several researches have shown strong relevance of adiponectin gene and metabolic disorders. In this review, the potential influence of epigenetic mechanisms of adiponectin gene “ADIPOQ” on increasing the risk of developing metabolic disorders and their potential in treating this major disorder are discussed.

Results & Conclusion::

Various studies have postulated that a series of factors such as maternal High fat diet (HFD), oxidative stress, pro-inflammatory mediators, sleep fragmentation throughout lifetime, from gestation to old age, could accumulate epigenetic marks, including histone remodeling, DNA methylation, and microRNAs (miRNAs) that, in turn, alter the expression of ADIPOQ gene and result in hypoadiponectinemia which precipitates insulin resistance (IR) that in turn might induce or accelerate the onset and development of metabolic disorder. A better understanding of global patterns of epigenetic modifications and further their alterations in metabolic disorders will bestow better treatment strategies design.

DNA methylation in promoter regions of genes involved in the reproductive and metabolic function of children born to women with PCOS

Clinical and experimental evidences indicate that epigenetic modifications induced by the prenatal environment are related to metabolic and reproductive derangements in polycystic ovary syndrome (PCOS). Alterations in the leptin and adiponectin systems, androgen signalling and antimüllerian hormone (AMH) levels have been observed in PCOS women and in their offspring. Using a targeted Next-Generation Sequencing (NGS), we studied DNA methylation in promoter regions of the leptin (LEP), leptin receptor (LEPR), adiponectin (ADIPOQ), adiponectin receptor 1 and 2 (ADIPOR1 and ADIPOR2), AMH and androgen receptor (AR) genes in 24 sons and daughters of women with PCOS (12 treated with metformin during pregnancy) and 24 children born to non-PCOS women during early infancy (2-3 months of age). Genomic DNA was extracted from whole blood, bisulphite converted and sequenced by NGS. Girls showed differences between groups in 1 CpG site of LEPR, 2 of LEP, 1 of ADIPOR2 and 2 of AR. Boys showed differences in 5 CpG sites of LEP, 3 of AMH and 9 of AR. Maternal metformin treatment prevented some of these changes in LEP, ADIPOR2 and partially in AR in girls, and in LEP and AMH in boys. Maternal BMI at early pregnancy was inversely correlated with the methylation levels of the ChrX-67544981 site in the whole group of girls (r = -0.530, p = 0.008) and with the global Z-score in all boys (r = -0.539, p = 0.007). These data indicate that the intrauterine PCOS environment predisposes the offspring to acquire certain sex-dependent DNA methylation patterns in the promoter regions of metabolic and reproductive genes.

Hyperandrogen enhances apoptosis of human ovarian granulosa cells via up-regulation and demethylation of PDCD4

Apoptosis of granulosa cells (GCs) induced by hyperandrogen plays a key role in the pathogenesis of polycystic ovary syndrome (PCOS). However, the mechanism of androgen-induced apoptosis of GCs has not been clarified to date. Recent studies have reported that PDCD4 expression is higher in PCOS patients and might be a key factor in PCOS progression. In this study, we aimed to investigate the role of PDCD4 in regulating apoptosis of human GCs and whether hyperandrogen regulate PDCD4 expression through DNA methylation. Overexpression of PDCD4 in human ovarian granulosa cell line KGN cells promoted cells apoptosis. Meanwhile, expression of caspase-3 and caspase-9 were significantly elevated. High concentration of testosterone treatment resulted in up-regulation of PDCD4 and a significant increase of apoptosis in KGN cells. In addition, knockdown of PDCD4 in KGN cells treated with high concentration of testosterone abolished the hyperandrogen-induced apoptosis. Furthermore, high concentration of testosterone down-regulated DNMT1, DNMT3A and DNMT3B expression and the methylation level in the promoter region of PDCD4 was decreased. In conclusion, PDCD4 can promote apoptosis of human ovarian GCs. The mechanism of hyperandrogen-induced apoptosis may be mediated by PDCD4. Furthermore, the up-regulation of PDCD4 induced by hyperandrogen may through demethylation of its promoter regions.

Recent advances in mammalian reproductive biology

Reproductive biology is a uniquely important topic since it is about germ cells, which are central for transmitting genetic information from generation to generation. In this review, we discuss recent advances in mammalian germ cell development, including preimplantation development, fetal germ cell development and postnatal development of oocytes and sperm. We also discuss the etiologies of female and male infertility and describe the emerging technologies for studying reproductive biology such as gene editing and single-cell technologies.

Gene Expression in Granulosa Cells From Small Antral Follicles From Women With or Without Polycystic Ovaries

CONTEXT

Polycystic ovary syndrome (PCOS) is the most common cause of anovulation. A key feature of PCOS is arrest of follicles at the small- to medium-sized antral stage.

OBJECTIVE AND DESIGN

To provide further insight into the mechanism of follicle arrest in PCOS, we profiled (i) gonadotropin receptors; (ii) characteristics of aberrant steroidogenesis; and (iii) expression of anti-Müllerian hormone (AMH) and its receptor in granulosa cells (GCs) from unstimulated, human small antral follicles (hSAFs) and from granulosa lutein cells (GLCs).

SETTING

GCs from hSAFs were collected at the time of cryopreservation of ovarian tissue for fertility preservation and GLCs collected during oocyte aspiration before in vitro fertilization/intracytoplasmic sperm injection.

PARTICIPANTS

We collected hSAF GCs from 31 women (98 follicles): 10 with polycystic ovaries (PCO) and 21 without. GLCs were collected from 6 women with PCOS and 6 controls undergoing IVF.

MAIN OUTCOME MEASURES

Expression of the following genes: LHCGR, FSHR, AR, INSR, HSD3B2, CYP11A1, CYP19, STAR, AMH, AMHR2, FST, INHBA, INHBB in GCs and GLCs were compared between women with PCO and controls.

RESULTS

GCs in hSAFs from women with PCO showed higher expression of LHCGR in a subset (20%) of follicles. Expression of FSHR (P < 0.05), AR (P < 0.05), and CYP11A1 (P < 0.05) was lower, and expression of CYP19A1 (P < 0.05), STAR (P < 0.05), HSD3B2 (P = NS), and INHBA (P < 0.05) was higher in PCO GCs. Gene expression in GL cells differed between women with and without PCOS but also differed from that in GCs.

CONCLUSIONS

Follicle arrest in PCO is characterized in GCs by differential regulation of key genes involved in follicle growth and function.

Emerging Topics in Cardiometabolic and Psychologic Sequelae, Pathogenesis, and Treatment of Polycystic Ovarian Syndrome: A Review

Polycystic ovarian syndrome (PCOS) is a common endocrine disorder, affecting 6–10% of reproductive age women and influences the reproductive, metabolic, dermatologic, and psychiatric health of affected girls and women. Despite its prevalence, the pathogenesis of the disease is largely unknown, and treatment options are limited. Thus, PCOS has been a ripe area for research in recent years, and novel etiologic pathways, diagnostic parameters, and treatment options are being explored. This review focuses on recent data suggesting pathogenic and therapeutic considerations, as well as the psychiatric and metabolic sequelae of PCOS.

DNA methylation in the pathogenesis of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the leading endocrine and metabolic disorder in premenopausal women characterized by hyperandrogenism and abnormal development of ovarian follicles. To date, the PCOS etiology remains unclear and has been related to insulin resistance, obesity, type 2 diabetes mellitus, cardiovascular disease and infertility, among other morbidities. Substantial evidence illustrates the impact of genetic, intrauterine and environmental factors on the PCOS etiology. Lately, epigenetic factors have garnered considerable attention in the pathogenesis of PCOS considering that changes in the content of DNA methylation, histone acetylation and noncoding RNAs have been reported in various tissues of women with this disease. DNA methylation is changed in the peripheral and umbilical cord blood, as well as in ovarian and adipose tissue of women with PCOS, suggesting the involvement of this epigenetic modification in the pathogenesis of the disease. Perhaps, these defects in DNA methylation promote the deregulation of genes involved in inflammation, hormone synthesis and signaling and glucose and lipid metabolism. Research on the role of DNA methylation in the pathogenesis of PCOS is just beginning, and several issues await investigation. This review aims to provide an overview of current research focused on DNA methylation and PCOS, as well as discuss the perspectives regarding this topic.

DNA methylome profiling of granulosa cells reveals altered methylation in genes regulating vital ovarian functions in polycystic ovary syndrome

Background

Women with polycystic ovary syndrome (PCOS) manifest a host of ovarian defects like impaired folliculogenesis, anovulation, and poor oocyte quality, which grossly affect their reproductive health. Addressing the putative epigenetic anomalies that tightly regulate these events is of foremost importance in this disorder. We therefore aimed to carry out DNA methylome profiling of cumulus granulosa cells and assess the methylation and transcript expression profiles of a few differentially methylated genes contributing to ovarian defects in PCOS. A total of 20 controls and 20 women with PCOS were selected from a larger cohort of women undergoing IVF, after carefully screening their sera and follicular fluids for hormonal and biochemical parameters. DNA extracted from cumulus granulosa cells of three women each, from control and PCOS groups was subjected to high-throughput, next generation bisulfite sequencing, using the Illumina HiSeq 2500® platform. Remaining samples were used for the validation of methylation status of some identified genes by pyrosequencing, and the transcript expression profiles of these genes were assessed by quantitative real-time PCR.

Results

In all, 6486 CpG sites representing 3840 genes associated with Wnt signaling, G protein receptor, endothelin/integrin signaling, angiogenesis, chemokine/cytokine-mediated inflammation, etc., showed differential methylation in PCOS. Hypomethylation was noted in 2977 CpGs representing 2063 genes while 2509 CpGs within 1777 genes showed hypermethylation. Methylation differences were also noted in noncoding RNAs regulating several ovarian functions that are dysregulated in PCOS. Few differentially methylated genes such as aldo-keto reductase family 1 member C3, calcium-sensing receptor, resistin, mastermind-like domain 1, growth hormone-releasing hormone receptor and tumor necrosis factor, which predominantly contribute to hyperandrogenism, premature luteolysis, and oocyte development defects, were explored as novel epigenetic candidates in mediating ovarian dysfunction. Methylation profiles of these genes matched with our NGS findings, and their transcript expression patterns correlated with the gene hypo- or hypermethylation status.

Conclusion

Our findings suggest that the epigenetic dysregulation of genes involved in important processes associated with follicular development may contribute to ovarian defects observed in women with PCOS.

Electronic supplementary material

The online version of this article (10.1186/s13148-019-0657-6) contains supplementary material, which is available to authorized users.

Rodent models of mental illness in polycystic ovary syndrome: the potential role of hypothalamic-pituitary-adrenal dysregulation and lessons for behavioral researchers

Polycystic ovary syndrome (PCOS) is the most commonly diagnosed endocrine disorder in women of reproductive age, with phenotypes including ovarian and metabolic dysfunctions. Women with PCOS also show increased rates of mental illness, dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, and altered responsiveness to stressors that may contribute to the higher rates of mental illness, specifically depression and anxiety. Animal models of PCOS have provided insight into the ovarian and metabolic mechanisms that underlie the syndrome, and several models have been used to study the behavioral consequences associated with PCOS in the laboratory. Several studies in rodent models of PCOS demonstrate changes in anxiety-like behavior, but researchers often neglect to report procedural details or behavioral data crucial to interpreting the differences observed in those studies. Additionally, the impact of potential HPA dysregulation in animal models of PCOS may influence behavioral findings, although only three studies to date have examined this. As such, researchers should consider and report stress-associated variables (e.g., time of day, light/dark cycle, light intensity, housing, and procedures to control experimenter and litter effects) that may influence depression- and anxiety-like behaviors in rodents. This review will summarize the behavioral and HPA-related studies in women with PCOS and rodent models of the disease, and provide considerations for future studies.

Hyperandrogenic origins of polycystic ovary syndrome - implications for pathophysiology and therapy

INTRODUCTION

Polycystic ovary syndrome (PCOS) diagnosis comprises combinations of female hyperandrogenism, menstrual irregularity and polycystic ovaries. While it is a familial and highly prevalent endocrine disorder, progress towards a cure is hindered by absence of a definitive pathogenic mechanism and lack of an animal model of naturally occurring PCOS.

AREAS COVERED

These include an overview of PCOS and its potential etiology, and an examination of insights gained into its pathogenic origins. Animal models derived from experimentally-induced hyperandrogenism during gestation, or from naturally-occurring PCOS-like traits, most reliably demonstrate reproductive, neuroendocrine and metabolic pathogenesis.

EXPERT OPINION

Genetic studies, while identifying at least 17 PCOS risk genes, account for <10% of women with PCOS. A number of PCOS risk genes involve regulation of gonadotropin secretion or action, suggesting a reproductive neuroendocrine basis for PCOS pathogenesis. Consistent with this notion, a number of animal models employing fetal androgen excess demonstrate epigenetic induction of PCOS-like traits, including reproductive neuroendocrine and metabolic dysfunction. Monkey models are most comprehensive, while mouse models provide molecular insight, including identifying the androgen receptor, particularly in neurons, as mediating androgen-induced PCOS-like programming. Naturally-occurring female hyperandrogenism is also demonstrated in monkeys. Animal models are poised to delineate molecular gateways to PCOS pathogenesis.

An International Consortium Update: Pathophysiology, Diagnosis, and Treatment of Polycystic Ovarian Syndrome in Adolescence

This paper represents an international collaboration of paediatric endocrine and other societies (listed in the Appendix) under the International Consortium of Paediatric Endocrinology (ICPE) aiming to improve worldwide care of adolescent girls with polycystic ovary syndrome (PCOS)1. The manuscript examines pathophysiology and guidelines for the diagnosis and management of PCOS during adolescence. The complex pathophysiology of PCOS involves the interaction of genetic and epigenetic changes, primary ovarian abnormalities, neuroendocrine alterations, and endocrine and metabolic modifiers such as anti-Müllerian hormone, hyperinsulinemia, insulin resistance, adiposity, and adiponectin levels. Appropriate diagnosis of adolescent PCOS should include adequate and careful evaluation of symptoms, such as hirsutism, severe acne, and menstrual irregularities 2 years beyond menarche, and elevated androgen levels. Polycystic ovarian morphology on ultrasound without hyperandrogenism or menstrual irregularities should not be used to diagnose adolescent PCOS. Hyperinsulinemia, insulin resistance, and obesity may be present in adolescents with PCOS, but are not considered to be diagnostic criteria. Treatment of adolescent PCOS should include lifestyle intervention, local therapies, and medications. Insulin sensitizers like metformin and oral contraceptive pills provide short-term benefits on PCOS symptoms. There are limited data on anti-androgens and combined therapies showing additive/synergistic actions for adolescents. Reproductive aspects and transition should be taken into account when managing adolescents.

Hypomethylation of specific CpG sites in the promoter region of steroidogeneic genes (GATA6 and StAR) in prenatally androgenized rats

INTRODUCTION

The methylation level of promoters is one of the most studied and well-known epigenetic mechanisms that programs the amount of gene expression. Over expression of steroidogenesis genes via epigenetic control can result in hypetandrogenism, which is the main endocrine aspect of polycystic ovarian syndrome (PCOS).

AIMS

In the present study we aimed to determine and compare the promoter methylation levels of three steroidogenic genes, CYP17, GATA6 and StAR, in theca cells of prenatally androgenized (PNA) rats to those of controls.

MATERIALS AND METHODS

Pregnant Wistar rats in the PNA group received 5 mg free testosterone, dissolved in 500 ml solvent, subcutaneously injected on day 20 of pregnancy, while controls were injected with 500 ml of solvent only. Theca cell samples, taken from the ovaries of eight to ten female offspring of both the PNA and control groups, were measured for promoter methylation levels of the aforementioned genes, using the bisulfite sequence PCR (BSP) method.

KEY FINDINGS

Although the promoters of all three genes were slightly hypomethylated in the PNA group, the differences observed were not significant compared to the control group. The methylation of -520 and -822 positions, in the GATA6 and the StAR promoter respectively, were significantly decreased in the PNA group.

SIGNIFICANCES

The results of this study suggest that alterations in the steroidogenesis pathway after exposure to excess androgen may be a result of changes in the pattern of the methylation of the relevant genes.

Aberrant expression and DNA methylation of lipid metabolism genes in PCOS: a new insight into its pathogenesis

Background

Polycystic ovary syndrome (PCOS), whose etiology remains uncertain, is a highly heterogenous and genetically complex endocrine disorder. The aim of this study was to identify differentially expressed genes (DEGs) in granulosa cells (GCs) from PCOS patients and make epigenetic insights into the pathogenesis of PCOS.

Results

Included in this study were 110 women with PCOS and 119 women with normal ovulatory cycles undergoing in vitro fertilization acting as the control group. RNA-seq identified 92 DEGs unique to PCOS GCs in comparison with the control group. Bioinformatic analysis indicated that synthesis of lipids and steroids was activated in PCOS GCs. 5-Methylcytosine analysis demonstrated that there was an approximate 25% reduction in global DNA methylation of GCs in PCOS women (4.44 ± 0.65%) compared with the controls (6.07 ± 0.72%; P < 0.05). Using MassArray EpiTYPER quantitative DNA methylation analysis, we also found hypomethylation of several gene promoters related to lipid and steroid synthesis, which might result in the aberrant expression of these genes.

Conclusions

Our results suggest that hypomethylated genes related to the synthesis of lipid and steroid may dysregulate expression of these genes and promote synthesis of steroid hormones including androgen, which could partially explain mechanisms of hyperandrogenism in PCOS.

Electronic supplementary material

The online version of this article (10.1186/s13148-018-0442-y) contains supplementary material, which is available to authorized users.

Comprehensive analysis of genome-wide DNA methylation across human polycystic ovary syndrome ovary granulosa cell

Polycystic ovary syndrome (PCOS) affects approximately 7% of the reproductive-age women. A growing body of evidence indicated that epigenetic mechanisms contributed to the development of PCOS. The role of DNA modification in human PCOS ovary granulosa cell is still unknown in PCOS progression. Global DNA methylation and hydroxymethylation were detected between PCOS’ and controls’ granulosa cell. Genome-wide DNA methylation was profiled to investigate the putative function of DNA methylaiton. Selected genes expressions were analyzed between PCOS’ and controls’ granulosa cell. Our results showed that the granulosa cell global DNA methylation of PCOS patients was significant higher than the controls’. The global DNA hydroxymethylation showed low level and no statistical difference between PCOS and control. 6936 differentially methylated CpG sites were identified between control and PCOS-obesity. 12245 differential methylated CpG sites were detected between control and PCOS-nonobesity group. 5202 methylated CpG sites were significantly differential between PCOS-obesity and PCOS-nonobesity group. Our results showed that DNA methylation not hydroxymethylation altered genome-wide in PCOS granulosa cell. The different methylation genes were enriched in development protein, transcription factor activity, alternative splicing, sequence-specific DNA binding and embryonic morphogenesis. YWHAQ, NCF2, DHRS9 and SCNA were up-regulation in PCOS-obesity patients with no significance different between control and PCOS-nonobesity patients, which may be activated by lower DNA methylaiton. Global and genome-wide DNA methylation alteration may contribute to different genes expression and PCOS clinical pathology.

Which origin for polycystic ovaries syndrome: Genetic, environmental or both?

Polycystic ovaries syndrome (PCOS), the most common female endocrine disorder, affects 7-10% of women of childbearing age. It includes ovarian hyperandrogenism, impaired follicular maturation, anovulation and subfertility. Insulin resistance, although present in most cases, is not necessary for diagnosis. It increases hyperandrogenism and long-term metabolic, cardiovascular and oncological risks. The origin of hyperandrogenism and hyperinsulinemia has a genetic component, as demonstrated by familial aggregation studies and recent identification of associated genomic variants, conferring a particular susceptibility to the syndrome. However, experimental and epidemiological evidences also support a developmental origin via a deleterious foetal environment, concerning the endocrine status (foetal hyperandrogenism), the nutritional level (intrauterine growth retardation), or the toxicological exposure (endocrine disruptors). Epigenetic changes recently reported in the literature as associated with PCOS, enhance this hypothesis of foetal reprogramming of the future adult ovarian function by environmental factors. Better characterisation of these genetic, epigenetic, or environmental factors, could lead to earlier prevention and more efficient treatments.

Epigenetic: A new approach to etiology of infertility

Infertility is a complex disease which could be caused by male and female factors. The etiology from both factors needs further study. There are some approaches to understanding the etiology of infertility, one of them is epigenetic. Epigenetic modifications consist of DNA methylation, histone modifications, and chromatin remodelling. Male and female germinal cells undergo epigenetic modifications dynamically during differentiation into matured sperm and oocyte cells. In a male, the alteration of DNA methylation in spermatogenesis will cause oligo/asthenozoospermia. In addition, the histone methylation, acetylation, or other histone modification may lead sperm lose its ability to fertilize oocyte. Similarly, in a female, the alteration of DNA methylation and histone modification affects oogenesis, created aneuploidy in fertilized oocytes and resulted in embryonic death in the uterus. Alteration of these epigenetic modification patterns will cause infertility, both in male and female.

Association between Common Genetic Variants and Polycystic Ovary Syndrome Risk in a Chinese Han Population

OBJECTIVE

Polycystic ovary syndrome (PCOS) is one of the most common endocrinopathies affecting 5-7% of reproductive age women worldwide. The aim of our study was to explore the PCOS-related single nucleotide polymorphism (SNP) associations between common genetic variants and PCOS risk in a Han Chinese women population.

METHODS

In this case-control study, 285 Chinese Han women aged 28.50±6.858 years with PCOS and 299 controls of a mean age of 32.66±7.018 years were compared. We selected recently published genome-wide association studies (GWAS) which identified several genetic loci in PCOS. All the SNPs were genotyped by Sequenom Mass-ARRAY technology. Associations between the gene and the risk of PCOS were tested using various genetic models by Statistical Package for the Social Sciences and Plink.

RESULTS

We found that rs705702 in the RAB5B/SUOX was associated with PCOS (odds ratio=1.42; 95% confidence interval=1.08-1.87, p=0.011) and increased the PCOS risk. The genotypic model analysis also showed that rs705702 was associated with PCOS risk.

CONCLUSION

Our results suggest that SNPs rs705702 in gene RAB5B/SUOX was associated with PCOS in Han Chinese women.

Changes in gene expression of histone modification enzymes in rat granulosa cells undergoing luteinization during ovulation

Background

The ovulatory LH surge rapidly alters the expression of steroidogenesis-related genes such as steroidogenic acute regulatory protein (StAR) in granulosa cells (GCs) undergoing luteinization. We recently reported that histone modifications contribute to these changes. Histone modifications are regulated by a variety of histone modification enzymes. This study investigated the changes in gene expression of histone modification enzymes in rat GCs undergoing luteinization after the induction of ovulation. The extracellular regulated kinase (ERK)-1/2 is a mediator in the intracellular signaling pathway stimulated by the ovulatory LH surge and regulates the expression of a number of genes in GCs. We further investigated whether ERK-1/2 is involved in the regulation of the histone modification at the StAR promoter region in GCs undergoing luteinization.

Results

GCs were obtained from rats treated with equine chorionic gonadotropin (CG) before (0 h) and after human (h) CG injection. The expressions of 84 genes regulating histone modifications or DNA methylation were measured using a PCR array. Five genes (HDAC4, HDAC10, EZH2, SETDB2, and CIITA) were identified as histone acetylation- or histone methylation-related genes, and were significantly altered after hCG injection. None of the genes were related to DNA methylation. mRNA levels of EZH2, SETDB2, HDAC4, and HDAC10 decreased and CIITA mRNA levels increased 4 or 12 h after hCG injection.

GCs isolated after eCG injection were incubated with hCG for 4 h to induce luteinization. StAR mRNA levels were significantly increased by hCG accompanied by the increase in H3K4me3 of the StAR promoter region. StAR mRNA expression was inhibited by the ERK inhibitor with the significant decrease of H3K4me3. These results suggest that hCG increases StAR gene expression through the ERK-1/2-mediated signaling which is also associated with histone modification of the promoter region.

Conclusions

Gene expressions of histone modification enzymes change in GCs undergoing luteinization after ovulation induction. This change may play important roles in regulating the expression of various genes during the early stage of luteinization, which may be critical for the subsequent corpus luteum formation.

Perspectives in Polycystic Ovary Syndrome: From Hair to Eternity

CONTEXT

Polycystic ovary syndrome (PCOS) is a common complex genetic disease. It is characterized by hyperandrogenism, gonadotropin secretory changes, polycystic ovarian morphology, and insulin resistance. The etiology of PCOS remains unknown, but modern genetic approaches, such as genome-wide association studies (GWAS), Mendelian randomization, and next-generation sequencing, promise to identify the pathways that are primarily disrupted.

EVIDENCE ACQUISITION

The literature on PCOS, including the author's research, is discussed.

EVIDENCE SYNTHESIS

Recent genetic analyses are reviewed.

CONCLUSIONS

Considerable progress has been made mapping PCOS susceptibility genes. GWAS have implicated gonadotropin secretion and action as important primary defects in disease pathogenesis in European and Han Chinese PCOS cohorts, respectively. European women with the National Institutes of Health and Rotterdam phenotypes as well as those with self-reported PCOS have some gene regions in common, such as chromosome 11p14.1 region containing the FSH B polypeptide (FSHB) gene, suggesting shared genetic susceptibility. Several chromosomal signals are significant in both Han Chinese and European PCOS cohorts, suggesting that the susceptibility genes in these regions are evolutionarily conserved. In addition, GWAS have suggested that DENND1A, epidermal growth factor signaling, and DNA repair pathways play a role in PCOS pathogenesis. Only a small amount of the heritability of PCOS is accounted for by the common susceptibility variants mapped so far. Future studies should clarify the contribution of rare genetic variants and epigenetic factors to the PCOS phenotype. Furthermore, Mendelian randomization can be used to clarify causal relationships, and phenome-wide association studies can provide insight into health risks associated with PCOS susceptibility variants.

miRNA-592 is downregulated and may target LHCGR in polycystic ovary syndrome patients

The polycystic ovary syndrome (PCOS) is an endocrine disorder mainly associated with infertility. Abnormal regulation of relevant genes is required for follicular development in PCOS. In the current study, the expression of serum miRNAs of PCOS patients was explored using miRNA array followed by qRT-PCR assays. The circulating level of miR-592 was significantly down-regulated in PCOS patients in comparison with healthy controls. Furthermore, we found that miR-592 was inversely correlated with the level of luteinizing hormone/chorionic gonadotropin receptor (LHCGR). Computational analysis predicted that miR-592 interacts with the LHCGR mRNA via binding to a site located in the 3'UTR region. Using a luciferase-based reporter assay we found that miR-592 directly targeted the LHCGR. In KGN cell line, miR-592 overexpression inhibited cell viability and the transition of phase G1 to phase S. Knocking down of LHCGR inhibited cell viability and cell cycle progression in KGN cells, and LHCGR co-transfection reversed the inhibitory effect of miR-592. These results shed new light on the diagnosis and treatment of PCOS syndrome.

Systems Genetics Reveals the Functional Context of PCOS Loci and Identifies Genetic and Molecular Mechanisms of Disease Heterogeneity

Genome wide association studies (GWAS) have revealed 11 independent risk loci for polycystic ovary syndrome (PCOS), a common disorder in young women characterized by androgen excess and oligomenorrhea. To put these risk loci and the single nucleotide polymorphisms (SNPs) therein into functional context, we measured DNA methylation and gene expression in subcutaneous adipose tissue biopsies to identify PCOS-specific alterations. Two genes from the LHCGR region, STON1-GTF2A1L and LHCGR, were overexpressed in PCOS. In analysis stratified by obesity, LHCGR was overexpressed only in non-obese PCOS women. Although not differentially expressed in the entire PCOS group, INSR was underexpressed in obese PCOS subjects only. Alterations in gene expression in the LHCGR, RAB5B and INSR regions suggest that SNPs in these loci may be functional and could affect gene expression directly or indirectly via epigenetic alterations. We identified reduced methylation in the LHCGR locus and increased methylation in the INSR locus, changes that are concordant with the altered gene expression profiles. Complex patterns of meQTL and eQTL were identified in these loci, suggesting that local genetic variation plays an important role in gene regulation. We propose that non-obese PCOS women possess significant alterations in LH receptor expression, which drives excess androgen secretion from the ovary. Alternatively, obese women with PCOS possess alterations in insulin receptor expression, with underexpression in metabolic tissues and overexpression in the ovary, resulting in peripheral insulin resistance and excess ovarian androgen production. These studies provide a genetic and molecular basis for the reported clinical heterogeneity of PCOS.

Polycystic ovary syndrome (PCOS) is the most common hormonal disturbance in reproductive age women and features high levels of male sex hormones, such as testosterone, and infrequent ovulation. Twin studies have demonstrated that inheritance plays a significant role in PCOS, and recent genome wide association studies (GWAS) have implicated 11 susceptibility regions. The mechanism by which these genetic loci cause PCOS has yet to be determined. We looked at DNA methylation and gene expression levels in these 11 loci in fat biopsies from women with and without PCOS. We identified differences in the expression of two receptors that bind hormones known to contribute to the pathogenesis of PCOS–the receptors for luteinizing hormone (LH) and insulin. We found increased expression of the LH receptor in non-obese PCOS women, while in the obese women with PCOS the insulin receptor was underexpressed. Both excess LH stimulation and elevated insulin levels, due to decreased receptor levels and resulting insulin resistance, can cause increased androgen production from the ovary. Our findings suggest the primary mechanism for elevated androgen levels in PCOS may differ between non-obese and obese women with PCOS and that the clinical heterogeneity seen in PCOS may have genetic underpinnings.

Polycystic Ovary Syndrome-Epigenetic Mechanisms and Aberrant MicroRNA

Polycystic ovary syndrome (PCOS) is the most common endocrinopathy in women of reproductive age affecting various functions including reproduction and metabolism. This syndrome is associated with increased prevalence of subclinical cardiovascular disease as well as endometrial and ovarian cancer. This syndrome is highly heterogeneous and it is not yet clear which factors are responsible for the development of a particular phenotype. Current research has shown that the interaction of susceptible and protective genomic variants under the influence of environmental factors can modify the clinical presentation via epigenetic modifications. MicroRNA (miRNA) are regulators of gene expression. Altered miRNA expression has been associated with various diseases such as diabetes, insulin resistance, inflammation, and cancer. Several miRNA have been identified in PCOS. This review examines the role of epigenetics and miRNA in the pathophysiology of this complex disease process.

Genome-wide DNA methylation and gene expression patterns provide insight into polycystic ovary syndrome development

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders in women. However, the epigenetic mechanism involved in PCOS progression remains largely unknown. Here, combining the DNA methylation profiling together with transcriptome analysis, we showed that (i) there were 7929 differentially methylated CpG sites (β > 0.1, P < 0.05) and 650 differential transcripts (fold change > 1.5, P < 0.005) in PCOS compared to normal ovaries; (ii) 54 genes were identified with methylated levels that were correlated with gene transcription in PCOS; and (iii) there were less hypermethylated sites, but many more hypomethylated sites residing in CpG islands and N_Shore in PCOS. Among these genes, we identified that several significant pathways, including the type I diabetes mellitus pathway, p53 signaling pathway and NOD-like receptor signaling pathway, and some immune and inflammatory diseases may be highly involved in PCOS development. These results suggested that differences in genome-wide DNA methylation and expression patterns exist between PCOS ovaries and normal ovaries; epigenetic mechanisms may in part be responsible for the different gene expression and PCOS phenotype. All of this may improve our understanding of the basic molecular mechanism underlying the development of PCOS.

Epigenetic pattern changes in prenatal female Sprague-Dawley rats following exposure to androgen

Androgen excess is generally considered to be one of the major characteristics of polycystic ovary syndrome (PCOS). Evidence from both clinical research and animal studies has revealed that this syndrome may have fetal origins, with epigenetics being proposed as the underlying mechanism. Our PCOS rat model induced by prenatal administration of 3mg testosterone from Embryonic Day (E) 16 to E19 showed polycystic ovaries, irregular oestrous cycles and endocrine disorders in adulthood. The methylation status of 16, 8 and 4 cytosine-phosphate-guanine (CpG) sites in the promoter regions of the androgen receptor (Ar), cytochrome P450 family 11, subfamily A, polypeptide 1 (Cyp11a1) and cytochrome P450, family 17, subfamily A, polypeptide 1 (Cyp17a1) genes, respectively, were measured by pyrosequencing. We identified three hypomethylated sites (CpG +58, +65 and +150) in Ar and one hypomethylated site (CpG +1016) in Cyp11a1 in peripheral blood cells of prenatally androgenised (PNA) rats. In ovarian tissue, five CpG sites of Ar (CpG +87, +91, +93, +98, +150) and one single CpG site in Cyp11a1 (CpG +953) were significantly hypomethylated in PNA rats, but the modified methylation of these two genes may not be sufficient to significantly alter levels of gene expression. Furthermore, tissue-specific methylation analysis revealed that both Ar and Cyp11a1 exhibited significant hypomethylation in testis in contrast with ovary and blood. PNA may lead to methylation pattern changes and the development of PCOS, but further studies are required to reveal causal relationships.

Intraovarian control of early folliculogenesis

Although hormonal regulation of ovarian follicle development has been extensively investigated, most studies concentrate on the development of early antral follicles to the preovulatory stage, leading to the successful use of exogenous FSH for infertility treatment. Accumulating data indicate that preantral follicles are under stringent regulation by FSH and local intraovarian factors, thus providing the possibility to develop new therapeutic approaches. Granulosa cell-derived C-type natriuretic factor not only suppresses the final maturation of oocytes to undergo germinal vesicle breakdown before ovulation but also promotes preantral and antral follicle growth. In addition, several oocyte- and granulosa cell-derived factors stimulate preantral follicle growth by acting through wingless, receptor tyrosine kinase, receptor serine kinase, and other signaling pathways. In contrast, the ovarian Hippo signaling pathway constrains follicle growth and disruption of Hippo signaling promotes the secretion of downstream CCN growth factors capable of promoting follicle growth. Although the exact hormonal factors involved in primordial follicle activation has yet to be elucidated, the protein kinase B (AKT) and mammalian target of rapamycin signaling pathways are important for the activation of dormant primordial follicles. Hippo signaling disruption after ovarian fragmentation, combined with treating ovarian fragments with phosphatase and tensin homolog (PTEN) inhibitors and phosphoinositide-3-kinase stimulators to augment AKT signaling, promote the growth of preantral follicles in patients with primary ovarian insufficiency, leading to a new infertility intervention for such patients. Elucidation of intraovarian mechanisms underlying early folliculogenesis may allow the development of novel therapeutic strategies for patients diagnosed with primary ovarian insufficiency, polycystic ovary syndrome, and poor ovarian response to FSH stimulation, as well as for infertile women of advanced reproductive age.

Further investigation in europeans of susceptibility variants for polycystic ovary syndrome discovered in genome-wide association studies of Chinese individuals

CONTEXT

Two genome-wide association studies (GWAS) of polycystic ovary syndrome (PCOS) have identified 11 susceptibility loci in Chinese individuals. Some of the risk loci identified in Chinese cohorts, mostly from the first GWAS, have been replicated in Europeans. Replication of the loci from the second GWAS in European cohorts is necessary to determine whether the same variants confer risk for PCOS in multiple ethnicities.

OBJECTIVE

The objective of the study was to determine the effects of the Chinese GWAS loci in European-origin individuals.

DESIGN

This was a genetic association study.

SETTING

The study was conducted at a tertiary care academic center.

PATIENTS

Eight hundred forty-five European subjects with PCOS and 845 controls participated in the study.

INTERVENTIONS

INTERVENTIONS included blood sampling and genotyping.

MAIN OUTCOME MEASURE

The association between PCOS and 12 independent single-nucleotide polymorphisms mapping to seven of the Chinese GWAS loci in a European cohort was measured.

RESULTS

Variants in DENND1A (P = .0002), THADA (P = .035), FSHR (P = .007), and INSR (P = .046) were associated with PCOS in Europeans. The genetic risk score, generated for each subject based on the total number of risk alleles, was associated with the diagnosis of PCOS (P < .0001) and remained associated (P = .02), even after exclusion of the four variants individually associated with PCOS.

CONCLUSIONS

At least four of the PCOS susceptibility loci identified in the Chinese GWAS are associated with PCOS in Europeans. The overall genetic burden for PCOS, as demonstrated by the risk score, is also associated with the diagnosis of PCOS in Europeans. The PCOS susceptibility loci identified in the Chinese GWAS are thus likely to play an important role in the etiology of PCOS across ethnicities.

New insights into the genetic basis of infertility

Infertility is a disease of the reproductive system characterized by inability to achieve pregnancy after 12 or more months of regular unprotected sexual intercourse. A variety of factors, including ovulation defects, spermatogenic failure, parental age, obesity, and infections have been linked with infertility, in addition to specific karyotypes and genotypes. The study of genes associated with infertility in rodent models has expanded the field of translational genetics in identifying the underlying cause of human infertility problems. Many intriguing aspects of the molecular basis of infertility in humans remain poorly understood; however, application of genetic knowledge in this field looks promising. The growing literature on the genetics of human infertility disorders deserves attention and a critical concise summary is required. This paper provides information obtained from a systematic analysis of the literature related to current research into the genetics of infertility affecting both sexes.