Erbb4 regulates the oocyte microenvironment during folliculogenesis

Ovarian-Specific Cyp17A1 Overexpression in Female Mice: A Novel Model of Endogenous Testosterone Excess

Excessive androgen levels can severely affect female health. However, most existing models of androgen excess rely on exogenous androgen administration, which does not fully capture the effect of elevated local ovarian testosterone on reproductive and metabolic functions. Here, we report the development of a novel hyperandrogenic mouse model, Cyp17TM-625, generated by combining CRISPR-Cas9 and a Tet-On doxycycline system to induce Cyp17A1 overexpression in ovarian theca-interstitial cells. As a result, Cyp17TM-625 mice exhibited significantly elevated Cyp17A1 messenger RNA and protein levels, accompanied by increased testosterone concentrations without alterations in basal levels of estradiol, progesterone, luteinizing hormone, or follicle-stimulating hormone. These mice demonstrated subfertility, evident by smaller and fewer litters, prolonged estrous cycles, and an increased number of unhealthy follicles with abnormally shaped oocytes. Despite these marked reproductive changes, body weight and glucose homeostasis remained comparable to Con-625 mice. Notably, withdrawal of doxycycline reversed testosterone overexpression and restored fertility over time. This model recapitulates reproductive dysfunction but not the metabolic disturbances, commonly observed in exogenous androgen models. The Cyp17TM-625 mouse line is a unique model for investigating the effects of local excess androgens on ovarian function. It also serves as a valuable tool for studying fertility restoration following the withdrawal of testosterone.

When IGF-1 Meets Metabolic Inflammation and Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a prevalent endocrine disorder associated with insulin resistance (IR) and hyperandrogenaemia (HA). Metabolic inflammation (MI), characterized by a chronic low-grade inflammatory state, is intimately linked with chronic metabolic diseases such as IR and diabetes and is also considered an essential factor in the development of PCOS. Insulin-like growth factor 1 (IGF-1) plays an essential role in PCOS pathogenesis through its multiple functions in regulating cell proliferation metabolic processes and reducing inflammatory responses. This review summarizes the molecular mechanisms by which IGF-1, via MI, participates in the onset and progression of PCOS, aiming to provide insights for studies and clinical treatment of PCOS.

Genetic and Epigenetic Landscape for Drug Development in Polycystic Ovary Syndrome

The treatment of polycystic ovary syndrome (PCOS) faces challenges as all known treatments are merely symptomatic. The US Food and Drug Administration has not approved any drug specifically for treating PCOS. As the significance of genetics and epigenetics rises in drug development, their pivotal insights have greatly enhanced the efficacy and success of drug target discovery and validation, offering promise for guiding the advancement of PCOS treatments. In this context, we outline the genetic and epigenetic advancement in PCOS, which provide novel insights into the pathogenesis of this complex disease. We also delve into the prospective method for harnessing genetic and epigenetic strategies to identify potential drug targets and ensure target safety. Additionally, we shed light on the preliminary evidence and distinctive challenges associated with gene and epigenetic therapies in the context of PCOS.

Calcium signaling induces partial EMT and renal fibrosis in a Wnt4mCherry knock-in mouse model

The renal tubular epithelial cells (TEC) have a strong capacity for repair after acute injury, but when this mechanism becomes uncontrollable, it leads to chronic kidney diseases (CKD). Indeed, in progress toward CKDs, the TECs may dedifferentiate, undergo epithelial-to-mesenchyme transition (EMT), and promote inflammation and fibrosis. Given the critical role of Wnt4 signaling in kidney ontogenesis, we addressed whether changes in this signaling are connected to renal inflammation and fibrosis by taking advantage of a knock-in Wnt4mCh/mCh mouse. While the Wnt4mCh/mCh embryos appeared normal, the corresponding mice, within one month, developed CKD-related phenotypes, such as pro-inflammatory responses including T-cell/macrophage influx, expression of fibrotic markers, and epithelial cell damage with a partial EMT. The Wnt signal transduction component β-catenin remained unchanged, while calcium signaling is induced in the injured TECs involving Nfat and Tfeb transcription factors. We propose that the Wnt4 signaling pathway is involved in repairing the renal injury, and when the signal is overdriven, CKD is established.

Unraveling the Genetic Associations of DENND1A (rs9696009) and ERBB4 (rs2178575) with Infertile Polycystic Ovary Syndrome Females in Pakistan

Polycystic Ovary Syndrome (PCOS) is a complex genetic disorder in reproductive-aged women which is associated with comorbidities of reproductive, metabolic, cardiovascular, endocrine, and psychological nature. PCOS is the most common cause of anovulatory infertility. Pathogenesis of PCOS involves strong interaction between environmental and genetic factors. Many Single-Nucleotide Polymorphisms (SNPs) have been associated with PCOS in different populations. Currently, very limited association studies of PCOS and infertility have been done on Pakistani population. The variants DENND1A rs9696009 and ERBB4 rs2178575 are significantly associated with PCOS in Chinese and European populations. These candidate genes regulate the production of androgen hormone, Anti-Mullerian Hormone (AMH), and luteinizing hormone. All these hormones are involved pathogenesis of PCOS and infertility. The aim of the study is to find an association of DENND1A rs9696009 and ERBB4 rs2178575 variants with PCOS in infertile Pakistani females. In this case-control study, 300 infertile females were recruited. The cases (n = 160) were infertile female diagnosed with PCOS (Rotterdam Criteria), and controls (n = 140) were infertile women with no evidence of PCOS. The genomic DNA was isolated, and genotyping was done by PCR-Restriction fragment length polymorphism and further validated by DNA Sanger Sequencing. The Chi-Square analysis showed rs2178575 (ERBB4) was significantly associated with infertility (χ2 = 10.282, p = 0.005852) while rs9696009 (DENND1A) did not show any significant association (χ2 = 3.10, p = 0.212036). Furthermore, multinomial logistic regression analysis was performed and revealed that rs2178575 (ERBB4) heterozygous genotypes (GA) and mutant genotypes (AA) decrease the risk of infertility by 0.541 times (OR = 0.541, 95% CI = 0.314-0.930, p = 0.026) and 0.416 times (OR = 0.416, 95% CI = 0.228-0.757, p = 0.004), respectively, compared to wild-type genotype (GG). The ERBB4 variant is significantly associated with PCOS infertile women and genetically indicated that ERBB4 (rs2178575) decreases the risk of infertility in females having PCOS.

Extracellular vesicles secreted by cumulus cells contain microRNAs that are potential regulatory factors of mouse oocyte developmental competence

The role of cumulus cells (CCs) in the acquisition of oocyte developmental competence is not yet fully understood. In a previous study, we matured cumulus-denuded fully-grown mouse oocytes to metaphase II (MII) on a feeder layer of CCs (FL-CCs) isolated from developmentally competent (FL-SN-CCs) or incompetent (FL-NSN-CCs) SN (surrounded nucleolus) or NSN (not surrounding nucleolus) oocytes, respectively. We observed that oocytes cultured on the former could develop into blastocysts, while those matured on the latter arrested at the 2-cell stage. To investigate the CC factors contributing to oocyte developmental competence, here we focused on the CCs' release into the medium of extracellular vesicles (EVs) and on their miRNA content. We found that, during the 15-h transition to MII, both FL-SN-CCs and FL-NSN-CCs release EVs that can be detected, by confocal microscopy, inside the zona pellucida (ZP) or the ooplasm. The majority of EVs are <200 nm in size, which is compatible with their ability to cross the ZP. Next-generation sequencing of the miRNome of FL-SN-CC versus FL-NSN-CC EVs highlighted 74 differentially expressed miRNAs, with 43 up- and 31 down-regulated. Although most of these miRNAs do not have known roles in the ovary, in silico functional analysis showed that seven of these miRNAs regulate 71 target genes with specific roles in meiosis resumption (N = 24), follicle growth (N = 23), fertilization (N = 1), and the acquisition of oocyte developmental competence (N = 23). Overall, our results indicate CC EVs as emerging candidates of the CC-to-oocyte communication axis and uncover a group of miRNAs as potential regulatory factors.

Body mass index stratified meta-analysis of genome-wide association studies of polycystic ovary syndrome in women of European ancestry

BACKGROUND

Polycystic ovary syndrome (PCOS) is a complex multifactorial disorder with a substantial genetic component. However, the clinical manifestations of PCOS are heterogeneous with notable differences between lean and obese women, implying a different pathophysiology manifesting in differential body mass index (BMI). We performed a meta-analysis of genome-wide association study (GWAS) data from six well-characterised cohorts, using a case-control study design stratified by BMI, aiming to identify genetic variants associated with lean and overweight/obese PCOS subtypes.

RESULTS

The study comprised 254,588 women (5,937 cases and 248,651 controls) from individual studies performed in Australia, Estonia, Finland, the Netherlands and United States of America, and separated according to three BMI stratifications (lean, overweight and obese). Genome-wide association analyses were performed for each stratification within each cohort, with the data for each BMI group meta-analysed using METAL software. Almost half of the total study population (47%, n = 119,584) were of lean BMI (≤ 25 kg/m2). Two genome-wide significant loci were identified for lean PCOS, led by rs12000707 within DENND1A (P = 1.55 × 10-12) and rs2228260 within XBP1 (P = 3.68 × 10-8). One additional locus, LINC02905, was highlighted as significantly associated with lean PCOS through gene-based analyses (P = 1.76 × 10-6). There were no significant loci observed for the overweight or obese sub-strata when analysed separately, however, when these strata were combined, an association signal led by rs569675099 within DENND1A reached genome-wide significance (P = 3.22 × 10-9) and a gene-based association was identified with ERBB4 (P = 1.59 × 10-6). Nineteen of 28 signals identified in previous GWAS, were replicated with consistent allelic effect in the lean stratum. There were less replicated signals in the overweight and obese groups, and only 4 SNPs were replicated in each of the three BMI strata.

CONCLUSIONS

Genetic variation at the XBP1, LINC02905 and ERBB4 loci were associated with PCOS within unique BMI strata, while DENND1A demonstrated associations across multiple strata, providing evidence of both distinct and shared genetic features between lean and overweight/obese PCOS-affected women. This study demonstrated that PCOS-affected women with contrasting body weight are not only phenotypically distinct but also show variation in genetic architecture; lean PCOS women typically display elevated gonadotrophin ratios, lower insulin resistance, higher androgen levels, including adrenal androgens, and more favourable lipid profiles. Overall, these findings add to the growing body of evidence supporting a genetic basis for PCOS as well as differences in genetic patterns relevant to PCOS BMI-subtype.

Induced Pluripotent Stem Cells as a Possible Approach for Exploring the Pathophysiology of Polycystic Ovary Syndrome (PCOS)

Polycystic ovary syndrome (PCOS) is the most prevalent endocrine condition among women with pleiotropic sequelae possessing reproductive, metabolic, and psychological characteristics. Although the exact origin of PCOS is elusive, it is known to be a complex multigenic disorder with a genetic, epigenetic, and environmental background. However, the pathogenesis of PCOS, and the role of genetic variants in increasing the risk of the condition, are still unknown due to the lack of an appropriate study model. Since the debut of induced pluripotent stem cell (iPSC) technology, the ability of reprogrammed somatic cells to self-renew and their potential for multidirectional differentiation have made them excellent tools to study different disease mechanisms. Recently, researchers have succeeded in establishing human in vitro PCOS disease models utilizing iPSC lines from heterogeneous PCOS patient groups (iPSCPCOS). The current review sets out to summarize, for the first time, our current knowledge of the implications and challenges of iPSC technology in comprehending PCOS pathogenesis and tissue-specific disease mechanisms. Additionally, we suggest that the analysis of polygenic risk prediction based on genome-wide association studies (GWAS) could, theoretically, be utilized when creating iPSC lines as an additional research tool to identify women who are genetically susceptible to PCOS. Taken together, iPSCPCOS may provide a new paradigm for the exploration of PCOS tissue-specific disease mechanisms.

Evidence of positive selection of genetic variants associated with PCOS

STUDY QUESTION

Was polycystic ovary syndrome (PCOS), which impairs fertility and adheres to the evolutionary paradox, subject to evolutionary selection during ancestral times and did rapidly diminish in prevalence?

SUMMARY ANSWER

This study strengthened the hypothesis that positive selection of genetic variants occurred and may account for the high prevalence of PCOS observed today.

WHAT IS KNOWN ALREADY

PCOS is a complex endocrine disorder characterized by both reproductive and metabolic disturbances. As a heritable disease that impairs fertility, PCOS should diminish rapidly in prevalence; however, it is the most common cause of female subfertility globally. Few scientific genetic studies have attempted to provide evidence for the positive selection of gene variants underlying PCOS.

STUDY DESIGN, SIZE, DURATION

We performed an evolutionary analysis of 2,504 individuals from 14 populations of the 1000 Genomes Project.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We tested the signature of positive selection for 37 single-nucleotide polymorphisms (SNPs) associated with PCOS in previous genome-wide association studies using six parameters of positive selection.

MAIN RESULTS AND THE ROLE OF CHANCE

Analyzing the evolutionary indices together, there was obvious positive selection at the PCOS-related SNPs loci, especially within the original evolution window of humans, demonstrated by significant Tajima's D values. Compared to the genome background, six of the 37 SNPs in or close to five genes (DENN domain-containing protein 1A: DENND1A, chromosome 9 open reading frame 3: AOPEP, aminopeptidase O: THADA, diacylglycerol kinase iota: DGKI, and netrin receptor UNC5C: UNC5C) showed significant evidence of positive selection, among which DENND1A, AOPEP, and THADA represent the set of most established susceptibility genes for PCOS.

LIMITATIONS, REASONS FOR CAUTION

First, only well-documented SNPs were selected from well-designed experiments. Second, it is difficult to determine which hypothesis of PCOS evolution is at play. After considering the most significant functions of these genes, we found that they had a wide variety of functions with no obvious association between them.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings provide additional evidence for the positive evolution of PCOS. Our analyses require confirmation in a larger study with more evolutionary indicators and larger data range. Further research to identify the roles of the DENND1A, AOPEP, THADA, DGKI, and UNC5C genes is also necessary.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the National Key Research and Development Program of China (2021YFC2700400 and 2021YFC2700701), Basic Science Center Program of NSFC (31988101), CAMS Innovation Fund for Medical Sciences (2021-I2M-5-001), National Natural Science Foundation of China (82192874, 31871509, and 82071606), Shandong Provincial Key Research and Development Program (2020ZLYS02), Taishan Scholars Program of Shandong Province (ts20190988), and Fundamental Research Funds of Shandong University. The authors have no conflicts of interest to disclose.

TRIAL REGISTRATION NUMBER

N/A.

Updated experimental cellular models to study polycystic ovarian syndrome

Polycystic ovarian syndrome (PCOS) develops due to hormonal imbalance and hyperandrogenism. Animal models are widely used to study PCOS because they mimic essential characteristics of human PCOS; however, the pathogenesis of PCOS remains unclear. Different sources of novel drugs are currently being screened as therapeutic strategies to alleviate PCOS and its symptoms. Simplified cell line in-vitro models could be preliminarily used to screen the bioactivity of various drugs. This review describes different cell line models focusing on the PCOS condition and its complications. Therefore, the bioactivity of the drugs could be preliminarily screened in a cell line model before moving to higher animal models.

Granulosa cell mevalonate pathway abnormalities contribute to oocyte meiotic defects and aneuploidy

With aging, abnormalities during oocyte meiosis become more prevalent. However, the mechanisms of aging-related oocyte aneuploidy are not fully understood. Here we performed Hi-C and SMART-seq of oocytes from young and old mice and reveal decreases in chromosome condensation and disrupted meiosis-associated gene expression in metaphase I oocytes from aged mice. Further transcriptomic analysis showed that meiotic maturation in young oocytes was correlated with robust increases in mevalonate (MVA) pathway gene expression in oocyte-surrounding granulosa cells (GCs), which was largely downregulated in aged GCs. Inhibition of MVA metabolism in GCs by statins resulted in marked meiotic defects and aneuploidy in young cumulus-oocyte complexes. Correspondingly, supplementation with the MVA isoprenoid geranylgeraniol ameliorated oocyte meiotic defects and aneuploidy in aged mice. Mechanically, we showed that geranylgeraniol activated LHR/EGF signaling in aged GCs and enhanced the meiosis-associated gene expression in oocytes. Collectively, we demonstrate that the MVA pathway in GCs is a critical regulator of meiotic maturation and euploidy in oocytes, and age-associated MVA pathway abnormalities contribute to oocyte meiotic defects and aneuploidy.

Deconstructing a Syndrome: Genomic Insights Into PCOS Causal Mechanisms and Classification

Polycystic ovary syndrome (PCOS) is among the most common disorders in women of reproductive age, affecting up to 15% worldwide, depending on the diagnostic criteria. PCOS is characterized by a constellation of interrelated reproductive abnormalities, including disordered gonadotropin secretion, increased androgen production, chronic anovulation, and polycystic ovarian morphology. It is frequently associated with insulin resistance and obesity. These reproductive and metabolic derangements cause major morbidities across the lifespan, including anovulatory infertility and type 2 diabetes (T2D). Despite decades of investigative effort, the etiology of PCOS remains unknown. Familial clustering of PCOS cases has indicated a genetic contribution to PCOS. There are rare Mendelian forms of PCOS associated with extreme phenotypes, but PCOS typically follows a non-Mendelian pattern of inheritance consistent with a complex genetic architecture, analogous to T2D and obesity, that reflects the interaction of susceptibility genes and environmental factors. Genomic studies of PCOS have provided important insights into disease pathways and have indicated that current diagnostic criteria do not capture underlying differences in biology associated with different forms of PCOS. We provide a state-of-the-science review of genetic analyses of PCOS, including an overview of genomic methodologies aimed at a general audience of non-geneticists and clinicians. Applications in PCOS will be discussed, including strengths and limitations of each study. The contributions of environmental factors, including developmental origins, will be reviewed. Insights into the pathogenesis and genetic architecture of PCOS will be summarized. Future directions for PCOS genetic studies will be outlined.

Brown adipose tissue-derived Nrg4 alleviates endothelial inflammation and atherosclerosis in male mice

Brown adipose tissue (BAT) activity contributes to cardiovascular health by its energy-dissipating capacity but how BAT modulates vascular function and atherosclerosis through endocrine mechanisms remains poorly understood. Here we show that BAT-derived neuregulin-4 (Nrg4) ameliorates atherosclerosis in mice. BAT-specific Nrg4 deficiency accelerates vascular inflammation and adhesion responses, endothelial dysfunction and apoptosis and atherosclerosis in male mice. BAT-specific Nrg4 restoration alleviates vascular inflammation and adhesion responses, attenuates leukocyte homing and reduces endothelial injury and atherosclerosis in male mice. In endothelial cells, Nrg4 decreases apoptosis, inflammation and adhesion responses induced by oxidized low-density lipoprotein. Mechanistically, protein kinase B (Akt)-nuclear factor-κB signaling is involved in the beneficial effects of Nrg4 on the endothelium. Taken together, the results reveal Nrg4 as a potential cross-talk factor between BAT and arteries that may serve as a target for atherosclerosis.

Update on Animal Models of Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a complex disease affecting up to 15% of women of reproductive age. Women with PCOS suffer from reproductive dysfunctions with excessive androgen secretion and irregular ovulation, leading to reduced fertility and pregnancy complications. The syndrome is associated with a wide range of comorbidities including type 2 diabetes, obesity, and psychiatric disorders. Despite the high prevalence of PCOS, its etiology remains unclear. To understand the pathophysiology of PCOS, how it is inherited, and how to predict PCOS, and prevent and treat women with the syndrome, animal models provide an important approach to answering these fundamental questions. This minireview summarizes recent investigative efforts on PCOS-like rodent models aiming to define underlying mechanisms of the disease and provide guidance in model selection. The focus is on new genetic rodent models, on a naturally occurring rodent model, and provides an update on prenatal and peripubertal exposure models.

Comprehensive analysis of differentially expressed profiles of mRNA, lncRNA, and miRNA of Yili geese ovary at different egg-laying stages

Background

The development of the ovaries is an important factor that affects egg production performance in geese. Ovarian development is regulated by genes that are expressed dynamically and stage-specifically. The transcriptome profile analysis on ovarian tissues of goose at different egg laying stages could provide an important basis for screening and identifying key genes regulating ovarian development.

Results

In this study, 4 ovary tissues at each breeding period of pre-laying (PP), laying (LP), and ceased-laying period (CP), respectively, with significant morphology difference, were used for RNA extraction and mRNAs, lncRNAs, and miRNAs comparison in Yili geese. CeRNA regulatory network was constructed for key genes screening. A total of 337, 1136, and 525 differentially expressed DE mRNAs, 466, 925, and 742 DE lncRNAs and 258, 1131 and 909 DE miRNAs were identified between PP and LP, between CP and LP, and between CP and PP groups, respectively. Functional enrichment analysis showed that the differentially expressed mRNAs and non-coding RNA target genes were mainly involved in the cell process, cytokine-cytokine receptor interaction, phagosome, calcium signaling pathway, steroid biosynthesis and ECM-receptor interaction. Differential genes and non-coding RNAs, PDGFRB, ERBB4, LHCGR, MSTRG.129094.34, MSTRG.3524.1 and gga-miR-145–5p, related to reproduction and ovarian development were highly enriched. Furthermore, lncRNA-miRNA-mRNA regulatory networks related to ovary development were constructed.

Conclusions

Our study found dramatic transcriptomic differences in ovaries of Yili geese at different egg-laying stages, and a differential lncRNA-miRNA-mRNA regulatory network related to cell proliferation, differentiation and apoptosis and involved in stromal follicle development were established and preliminarily validated, which could be regarded as a key regulatory pathway of ovarian development in Yili geese.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08774-4.

Leveraging Northern European population history: novel low-frequency variants for polycystic ovary syndrome

STUDY QUESTION

Can we identify novel variants associated with polycystic ovary syndrome (PCOS) by leveraging the unique population history of Northern Europe?

SUMMARY ANSWER

We identified three novel genome-wide significant associations with PCOS, with two putative independent causal variants in the checkpoint kinase 2 (CHEK2) gene and a third in myosin X (MYO10).

WHAT IS KNOWN ALREADY

PCOS is a common, complex disorder with unknown aetiology. While previous genome-wide association studies (GWAS) have mapped several loci associated with PCOS, the analysis of populations with unique population history and genetic makeup has the potential to uncover new low-frequency variants with larger effects.

STUDY DESIGN, SIZE, DURATION

A population-based case-control GWAS was carried out.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We identified PCOS cases from national registers by ICD codes (ICD-10 E28.2, ICD-9 256.4, or ICD-8 256.90), and all remaining women were considered controls. We then conducted a three-stage case-control GWAS: in the discovery phase, we had a total of 797 cases and 140 558 controls from the FinnGen study. For validation, we used an independent dataset from the Estonian Biobank, including 2812 cases and 89 230 controls. Finally, we performed a joint meta-analysis of 3609 cases and 229 788 controls from both cohorts. Additionally, we reran the association analyses including BMI as a covariate, with 2169 cases and 160 321 controls from both cohorts.

MAIN RESULTS AND THE ROLE OF CHANCE

Two out of the three novel genome-wide significant variants associating with PCOS, rs145598156 (P = 3.6×10-8, odds ratio (OR) = 3.01 [2.02-4.50] minor allele frequency (MAF) = 0.005) and rs182075939 (P = 1.9×10-16, OR = 1.69 [1.49-1.91], MAF = 0.04), were found to be enriched in the Finnish and Estonian populations and are tightly linked to a deletion c.1100delC (r2 = 0.95) and a missense I157T (r2 = 0.83) in CHEK2. The third novel association is a common variant near MYO10 (rs9312937, P = 1.7 × 10-8, OR = 1.16 [1.10-1.23], MAF = 0.44). We also replicated four previous reported associations near the genes Erb-B2 Receptor Tyrosine Kinase 4 (ERBB4), DENN Domain Containing 1A (DENND1A), FSH Subunit Beta (FSHB) and Zinc Finger And BTB Domain Containing 16 (ZBTB16). When adding BMI as a covariate only one of the novel variants remained genome-wide significant in the meta-analysis (the EstBB lead signal in CHEK2 rs182075939, P = 1.9×10-16, OR = 1.74 [1.5-2.01]) possibly owing to reduced sample size.

LARGE SCALE DATA

The age- and BMI-adjusted GWAS meta-analysis summary statistics are available for download from the GWAS Catalog with accession numbers GCST90044902 and GCST90044903.

LIMITATIONS, REASONS FOR CAUTION

The main limitation was the low prevalence of PCOS in registers; however, the ones with the diagnosis most likely represent the most severe cases. Also, BMI data were not available for all (63% for FinnGen, 76% for EstBB), and the biobank setting limited the accessibility of PCOS phenotypes and laboratory values.

WIDER IMPLICATIONS OF THE FINDINGS

This study encourages the use of isolated populations to perform genetic association studies for the identification of rare variants contributing to the genetic landscape of complex diseases such as PCOS.

STUDY FUNDING/COMPETING INTEREST(S)

This work has received funding from the European Union's Horizon 2020 research and innovation programme under the MATER Marie Skłodowska-Curie grant agreement No. 813707 (N.P.-G., T.L., T.P.), the Estonian Research Council grant (PRG687, T.L.), the Academy of Finland grants 315921 (T.P.), 321763 (T.P.), 297338 (J.K.), 307247 (J.K.), 344695 (H.L.), Novo Nordisk Foundation grant NNF17OC0026062 (J.K.), the Sigrid Juselius Foundation project grants (T.L., J.K., T.P.), Finska Läkaresällskapet (H.L.) and Jane and Aatos Erkko Foundation (H.L.). The funders had no role in study design, data collection and analysis, publishing or preparation of the manuscript. The authors declare no conflicts of interest.

Hsa-mir-548 family expression in human reproductive tissues

BACKGROUND

Hsa-miR-548ba expressed in ovarian granulosa cells targets PTEN and LIFR, which are essential for ovarian follicle activation and growth. The expression pattern of hsa-miR-548ba correlates with its host gene follicle-stimulating hormone receptor (FSHR), and FSH has a positive influence on hsa-miR-548ba expression. However, hsa-miR-548ba is a member of a large hsa-mir-548 family with potentially overlapping targets. The current study aims to investigate the co-expression of hsa-mir-548 family members in FSHR-positive reproductive tissues and to explore the potential co-regulation of pathways.

RESULTS

For the above-described analysis, small RNA sequencing data from public data repositories were used. Sequencing results revealed that hsa-miR-548ba was expressed at the highest level in the ovarian granulosa cells and uterine myometrial samples together with another twelve and one hsa-miR-548 family members, respectively. Pathway enrichment analysis of microRNA targets in the ovarian samples revealed the hsa-miR-548ba and hsa-miR-548b-5p co-regulation of RAB geranylgeranylation in mural granulosa cells. Moreover, other hsa-mir-548 family members co-regulate pathways essential for ovarian functions (PIP3 activates AKT signalling and signalling by ERBB4). In addition to hsa-miR-548ba, hsa-miR-548o-3p is expressed in the myometrium, which separately targets the peroxisome proliferator-activated receptor alpha (PPARA) pathway.

CONCLUSION

This study reveals that hsa-mir-548 family members are expressed in variable combinations in the reproductive tract, where they potentially fulfil different regulatory roles. The results provide a reference for further studies of the hsa-mir-548 family role in the reproductive tract.