Expression pattern of endothelin system components and localization of smooth muscle cells in the human pre-ovulatory follicle

Common mechanisms of physiological and pathological rupture events in biology: novel insights into mammalian ovulation and beyond

Ovulation is a cyclical biological rupture event fundamental to fertilisation and endocrine function. During this process, the somatic support cells that surround the germ cell undergo a remodelling process that culminates in breakdown of the follicle wall and release of a mature egg. Ovulation is driven by known proteolytic and inflammatory pathways as well as structural alterations to the follicle vasculature and the fluid-filled antral cavity. Ovulation is one of several types of systematic remodelling that occur in the human body that can be described as rupture. Although ovulation is a physiological form of rupture, other types of rupture occur in the human body which can be pathological, physiological, or both. In this review, we use intracranial aneurysms and chorioamniotic membrane rupture as examples of rupture events that are pathological or both pathological and physiological, respectively, and compare these to the rupture process central to ovulation. Specifically, we compared existing transcriptomic profiles, immune cell functions, vascular modifications, and biomechanical forces to identify common processes that are conserved between rupture events. In our transcriptomic analysis, we found 12 differentially expressed genes in common among two different ovulation data sets and one intracranial aneurysm data set. We also found three genes that were differentially expressed in common for both ovulation data sets and one chorioamniotic membrane rupture data set. Combining analysis of all three data sets identified two genes (Angptl4 and Pfkfb4) that were upregulated across rupture systems. Some of the identified genes, such as Rgs2, Adam8, and Lox, have been characterised in multiple rupture contexts, including ovulation. Others, such as Glul, Baz1a, and Ddx3x, have not yet been characterised in the context of ovulation and warrant further investigation as potential novel regulators. We also identified overlapping functions of mast cells, macrophages, and T cells in the process of rupture. Each of these rupture systems share local vasoconstriction around the rupture site, smooth muscle contractions away from the site of rupture, and fluid shear forces that initially increase and then decrease to predispose one specific region to rupture. Experimental techniques developed to study these structural and biomechanical changes that underlie rupture, such as patient-derived microfluidic models and spatiotemporal transcriptomic analyses, have not yet been comprehensively translated to the study of ovulation. Review of the existing knowledge, transcriptomic data, and experimental techniques from studies of rupture in other biological systems yields a better understanding of the physiology of ovulation and identifies avenues for novel studies of ovulation with techniques and targets from the study of vascular biology and parturition.

Application of Single-Cell RNA Sequencing in Ovarian Development

The ovary is a female reproductive organ that plays a key role in fertility and the maintenance of endocrine homeostasis, which is of great importance to women's health. It is characterized by a high heterogeneity, with different cellular subpopulations primarily containing oocytes, granulosa cells, stromal cells, endothelial cells, vascular smooth muscle cells, and diverse immune cell types. Each has unique and important functions. From the fetal period to old age, the ovary experiences continuous structural and functional changes, with the gene expression of each cell type undergoing dramatic changes. In addition, ovarian development strongly relies on the communication between germ and somatic cells. Compared to traditional bulk RNA sequencing techniques, the single-cell RNA sequencing (scRNA-seq) approach has substantial advantages in analyzing individual cells within an ever-changing and complicated tissue, classifying them into cell types, characterizing single cells, delineating the cellular developmental trajectory, and studying cell-to-cell interactions. In this review, we present single-cell transcriptome mapping of the ovary, summarize the characteristics of the important constituent cells of the ovary and the critical cellular developmental processes, and describe key signaling pathways for cell-to-cell communication in the ovary, as revealed by scRNA-seq. This review will undoubtedly improve our understanding of the characteristics of ovarian cells and development, thus enabling the identification of novel therapeutic targets for ovarian-related diseases.

Association of Polymorphisms in the Long Non-Coding RNA HOTAIR with Recurrent Pregnancy Loss in a Korean Population

Recurrent pregnancy loss (RPL) affects 1% to 5% of women, with devastating effects on both reproductive health and psychological well-being. Homeobox (HOX) transcript antisense RNA (HOTAIR) is a long non-coding RNA (lncRNA) produced by HOXC; it plays a major role in invasion and development of ovarian and other cancers. The aim of the present study was to analyze effects of HOTAIR polymorphisms (rs4759314 A>G, rs920778 T>C, rs1899663 G>T, and rs7958904 G>C) on RPL in Korean women. A total of 403 women with RPL and 383 healthy women were selected for this study. Genotyping analysis was performed with the polymerase chain reaction, restriction fragment length polymorphism, and the TaqMan genotyping assay. Clinical characteristics were compared using Student's unpaired t-test and the chi-square test for categorical variables. Logistic regression was performed to evaluate associations between single nucleotide polymorphisms and RPL incidence. In all assays, p < 0.05 was considered significant. HOTAIR polymorphisms rs4759314A>G and rs920778T>C were highly associated with increased risk of RPL, specifically the haplotypes rs4759314A>G/rs1899663G>T (G-T) and rs4759314A>G/rs920778 T>C (G-C). These associations were maintained in haplotypes that contained three polymorphisms (rs4759314 A>G, rs920778 T>C, and rs1899663 G>T) A-C-G, G-T-G, and G-T-T, further indicating that the HOTAIR rs4759314 and rs920778 polymorphisms play significant roles in idiopathic RPL in Korean women.

Intraovarian, Isoform-Specific Transcriptional Roles of Progesterone Receptor in Ovulation

Progesterone receptor (PGR) activity is obligatory for mammalian ovulation; however, there is no established direct functional pathway explaining how progesterone receptor completely and specifically regulates oocyte release. This study examined the overarching cell- and isoform-specific effects of the PGR within each cellular compartment of the ovary, using mice null for the PGR (PRKO), as well as isoform-specific null mice. The PGR was expressed in ovarian granulosa and stromal cells and although PRKO ovaries showed no visible histological changes in preovulatory ovarian morphology, follicle rupture did not occur. Reciprocal ovarian transplant experiments established the necessity of ovarian PGR expression for ovulation. Cumulus–oocyte complexes of PRKO mice exhibited normal morphology but showed some altered gene expression. The examination of mitochondrial activity showed subtle differences in PRKO oocytes but no differences in granulosa cell respiration, glycolysis or β-oxidation. Concurrently, RNA-seq identified novel functional pathways through which the PGR may regulate ovulation. PGR-A was the predominant transcriptionally active isoform in granulosa cells and 154 key PGR-dependent genes were identified, including a secondary network of transcription factors. In addition, the PGR regulated unique gene networks in the ovarian stroma. Collectively, we establish the effector pathways activated by the PGR across the ovarian cell types and conclude that PGR coordinates gene expression in the cumulus, granulosa and stromal cells at ovulation. Identifying these networks linking the PGR to ovulation provides novel targets for fertility therapeutics and nonhormonal contraceptive development.

Reduced Endothelin-2 and Hypoxic Signaling Pathways in Granulosa-Lutein Cells of PCOS Women

Granulosa-lutein cells (GLCs) from PCOS women display reduced HIF-1α and EDN2 levels, suggesting their role in PCOS etiology. Here, we investigated the mechanisms involved in aberrant EDN2 expression in PCOS, and its association with HIF-1α. Various HIF-1α-dependent factors were studied in GLCs from PCOS and compared to normally ovulating women. MicroRNA-210 (miR-210), its target genes (SDHD and GPD1L), and HIF-1α-responsive genes (EDN2 and VEGFA) differed in GLCs from PCOS, compared with those of healthy women. Levels of miR-210—designated hypoxiamiR—and EDN2 were reduced in the PCOS GLCs; concomitantly, GPD1L and SDHD levels were elevated. Cultured GLCs retained low EDN2 expression and had low HIF-1α levels, providing evidence for a disrupted hypoxic response in the PCOS GLCs. However, VEGFA expression was elevated in these cells. Next, miR-210 levels were manipulated. miR-210-mimic stimulated EDN2 twice as much as the miR-NC-transfected cells, whereas miR-210-inhibitor diminished EDN2, emphasizing the importance of hypoxiamiR for EDN2 induction. Intriguingly, VEGFA transcripts were reduced by both miR-210-mimic and -inhibitor, demonstrating that EDN2 and VEGFA are distinctly regulated. Disrupted hypoxic response in the GLCs of periovulatory follicles in PCOS women may play a role in ovulation failure, and in the reduced fertility prevalent in this syndrome.

Estradiol Regulates mRNA Levels of Estrogen Receptor Beta 4 and Beta 5 Isoforms and Modulates Human Granulosa Cell Apoptosis

Estrogen receptor beta (ERβ) plays a critical role in granulosa cell (GC) functions. The existence of four human ERβ splice isoforms in the ovary suggests their differential implication in 17β-estradiol (E2) actions on GC apoptosis causing follicular atresia. In this study, we investigated whether E2 can regulate ERβ isoforms expression to fine tune its apoptotic activities in human GC. For this purpose, we measured by RT-qPCR the expression of ERβ isoforms in primary culture of human granulosa cells (hGCs) collected from patients undergoing in vitro fertilization, before and after E2 exposure. Besides, we assessed the potential role of ERβ isoforms on cell growth and apoptosis after their overexpression in a human GC line (HGrC1 cells). We confirmed that ERβ1, ERβ2, ERβ4, and ERβ5 isoform mRNAs were predominant over that of ERα in hGCs, and found that E2 selectively regulates mRNA levels of ERβ4 and ERβ5 isoforms in these cells. In addition, we demonstrated that overexpression of ERβ1 and ERβ4 in HGrC1 cells increased cell apoptosis by 225% while ERβ5 or ERβ2 had no effect. Altogether, our study revealed that E2 may influence GC fate by specifically regulating the relative abundance of ERβ isoforms mRNA to modulate the balance between pro-apoptotic and non-apoptotic ERβ isoforms.

Functional Variants Surrounding Endothelin 2 Are Associated With Mycobacterium avium Subspecies paratuberculosis Infection

Bovine paratuberculosis, caused by Mycobacterium avium subspecies paratuberculosis (MAP), continues to impact the dairy industry through increased morbidity, mortality, and lost production. Although genome-wide association analyses (GWAAs) have identified loci associated with susceptibility to MAP, limited progress has been made in identifying mutations that cause disease susceptibility. A 235-kb region on Bos taurus chromosome 3 (BTA3), containing a 70-kb haplotype block surrounding endothelin 2 (EDN2), has previously been associated with the risk of MAP infection. EDN2 is highly expressed in the gut and is involved in intracellular calcium signaling and a wide array of biological processes. The objective of this study was to identify putative causal mutations for disease susceptibility in the region surrounding EDN2 in Holstein and Jersey cattle. Using sequence data from 10 Holstein and 10 Jersey cattle, common variants within the 70-kb region containing EDN2 were identified. A custom SNP genotyping array fine-mapped the region using 221 Holstein and 51 Jersey cattle and identified 17 putative causal variants (P < 0.01) located in the 5′ region of EDN2 and a SNP in the 3′ UTR (P = 0.00009) associated with MAP infection. MicroRNA interference assays, mRNA stability assays, and electrophoretic mobility shift assays were performed to determine if allelic changes at each SNP resulted in differences in EDN2 stability or expression. Two SNPs [rs109651404 (G/A) and rs110287192 (G/T)] located within the promoter region of EDN2 displayed differential binding affinity for transcription factors in binding sequences harboring the alternate SNP alleles. The luciferase reporter assay revealed that the transcriptional activity of the EDN2 promoter was increased (P < 0.05) with the A allele for rs109651404 and the G allele for rs110287192. These results suggest that the variants rs109651404 and rs110287192 are mutations that alter transcription and thus may alter susceptibility to MAP infection in Holstein and Jersey cattle.

Associations between HOTAIR polymorphisms rs4759314, rs920778, rs1899663, and rs7958904 and risk of primary ovarian insufficiency in Korean women

BACKGROUND

We investigated the association between the Hox transcript antisense RNA (HOTAIR) polymorphisms rs4759314, rs920778, rs1899663, and rs7958904 and primary ovarian insufficiency (POI) in Korean women.

METHODS

We conducted a case-control study of 134 Korean women with POI and 383 control individuals with at least one live birth and no history of pregnancy loss.

RESULTS

The GT genotype of rs1899663 was associated with a decreased risk of POI compared with other genotypes at that locus. In addition, compared with the wild-type homozygous genotypes, the combination of the AA genotype of rs4759314 and the GC genotype of rs7958904 was associated with a decreased risk of POI (P < 0.05), whereas the combination of the GG genotype of rs1899663 and the GC genotype of rs7958904 was associated with an increased risk of POI (P = 0.003). Haplotype analysis revealed that certain haplotypes involving some or all of the polymorphisms were associated with a decreased risk of POI, whereas other haplotypes were associated with an increased risk of POI. Serum levels of luteinizing hormone, follicle-stimulating hormone, and estradiol differed between patients with POI and control individuals (P < 0.05).

CONCLUSIONS

Our results suggest that the HOTAIR polymorphisms rs4759314, rs920778, rs1899663, and rs7958904 are involved in POI.

Sirtuin-1 inhibits endothelin-2 expression in human granulosa-lutein cells via hypoxia inducible factor 1 alpha and epigenetic modifications†

Endothelin-2 (EDN2) expression in granulosa cells was previously shown to be highly dependent on the hypoxic mediator, hypoxia inducible factor 1 alpha (HIF1A). Here, we investigated whether sirtuin-1 (SIRT1), by deacetylating HIF1A and class III histones, modulates EDN2 in human granulosa-lutein cells (hGLCs). We found that HIF1A was markedly suppressed in the presence of resveratrol or a specific SIRT1 activator, SRT2104. In turn, hypoxia reduced SIRT1 levels, implying a mutually inhibitory interaction between hypoxia (HIF1A) and SIRT1. Consistent with reduced HIF1A transcriptional activity, SIRT1 activators, resveratrol, SRT2104, and metformin, each acting via different mechanisms, significantly inhibited EDN2. In support, knockdown of SIRT1 with siRNA markedly elevated EDN2, whereas adding SRT2104 to SIRT1-silenced cells abolished the stimulatory effect of siSIRT1 on EDN2 levels further demonstrating that EDN2 is negatively correlated with SIRT1. Next, we investigated whether SIRT1 can also mediate the repression of the EDN2 promoter via histone modification. Chromatin immunoprecipitation (ChIP) analysis revealed that SIRT1 is indeed bound to the EDN2 promoter and that elevated SIRT1 induced a 40% decrease in the acetylation of histone H3, suggesting that SIRT1 inhibits EDN2 promoter activity by inducing a repressive histone configuration. Importantly, SIRT1 activation, using SRT2104 or resveratrol, decreased the viable numbers of hGLC, and silencing SIRT1 enhanced hGLC viability. This effect may be mediated by reducing HIF1A and EDN2 levels, shown to promote cell survival. Taken together, these findings propose novel, physiologically relevant roles for SIRT1 in downregulating EDN2 and survival of hGLCs.

Association between microRNA machinery gene polymorphisms and recurrent implantation failure

The present study aimed to investigate the potential association of five miRNA machinery gene polymorphisms (DICER1 rs3742330A>G, DROSHA rs10719T>C, RAN rs14035C>T, XPO5 rs11077A>C and DGCR8 rs417309G>A) with recurrent implantation failure (RIF), a clinical condition in which good-quality embryos repeatedly fail to implant following two or more in vitro fertilization cycles, and its associated risk factors in Korean women. Therefore, the present study performed genotype analysis and assessed the frequency of these miRNA gene polymorphisms in patients diagnosed with RIF (n=119) and randomly selected controls (n=210) with at least one live birth and no history of pregnancy loss. The DROSHA rs10719T>C and RAN rs14035C>T polymorphisms were identified to be significantly associated with decreased prevalence of RIF. Additionally, the DROSHA rs10719 TC and the RAN rs14035 CT genotypes were present at significantly lower frequencies in the RIF group than in the control group (adjusted odds ratio=0.550; 95% CI, 0.339-0.893; P=0.016; and adjusted odds ratio=0.590; 95% CI, 0.363-0.958; P=0.033, respectively). Furthermore, the combined RAN rs14035 CT+TT genotype was observed to be associated with decreased RIF prevalence (adjusted odds ratio=0.616; 95% CI, 0.386-0.982; P=0.042). Genotype combination analysis for the various miRNA polymorphisms revealed that the DROSHA TC genotype exhibited a highly significant negative association with RIF prevalence when combined with the RAN CT genotype (adjusted odds ratio=0.314; 95% CI, 0.147-0.673; P=0.003; false discovery rate-adjusted P=0.023). The present study revealed an association between the DROSHA rs10719 and RAN rs14035 3'UTR polymorphisms and decreased risk of RIF in Korean women, which suggests that these gene polymorphisms could represent potential markers for predicting RIF risk.

A putative silencer variant in a spontaneous canine model of retinitis pigmentosa

Retinitis pigmentosa (RP) is the leading cause of blindness with nearly two million people affected worldwide. Many genes have been implicated in RP, yet in 30–80% of the RP patients the genetic cause remains unknown. A similar phenotype, progressive retinal atrophy (PRA), affects many dog breeds including the Miniature Schnauzer. We performed clinical, genetic and functional experiments to identify the genetic cause of PRA in the breed. The age of onset and pattern of disease progression suggested that at least two forms of PRA, types 1 and 2 respectively, affect the breed, which was confirmed by genome-wide association study that implicated two distinct genomic loci in chromosomes 15 and X, respectively. Whole-genome sequencing revealed a fully segregating recessive regulatory variant in type 1 PRA. The associated variant has a very recent origin based on haplotype analysis and lies within a regulatory site with the predicted binding site of HAND1::TCF3 transcription factor complex. Luciferase assays suggested that mutated regulatory sequence increases expression. Case-control retinal expression comparison of six best HAND1::TCF3 target genes were analyzed with quantitative reverse-transcriptase PCR assay and indicated overexpression of EDN2 and COL9A2 in the affected retina. Defects in both EDN2 and COL9A2 have been previously associated with retinal degeneration. In summary, our study describes two genetically different forms of PRA and identifies a fully penetrant variant in type 1 form with a possible regulatory effect. This would be among the first reports of a regulatory variant in retinal degeneration in any species, and establishes a new spontaneous dog model to improve our understanding of retinal biology and gene regulation while the affected breed will benefit from a reliable genetic testing.

Retinitis pigmentosa (RP) is a blinding eye disease that affects nearly two million people worldwide. Several genes and variants have been associated with the disease, but still 30–80% of the patients lack genetic diagnosis. There is currently no standard treatment for RP, and much is expected from gene therapy. A similar disease, called progressive retinal atrophy (PRA), affects many dog breeds. We performed clinical, genetic and functional analyses to find the genetic cause for PRA in Miniature Schnauzers. We discovered two forms of PRA in the breed, named type 1 and 2, and show that they are genetically distinct as they map to different chromosomes, 15 and X, respectively. Further genetic, bioinformatic and functional analyses discovered a fully penetrant recessive variant in a putative silencer region for type 1 PRA. Silencer regions are important for gene regulation and we found that two of its predicted target genes, EDN2 and COL9A2, were overexpressed in the retina of the affected dog. Defects in both EDN2 and COL9A2 have been associated with retinal degeneration. This study provides new insights to retinal biology while the genetic test guides better breeding choices.

The direct effects of gonadotropin-releasing hormone on proliferation of granulosa cells and development of follicles in goose

1. The study objectives were to determine the direct effects of gonadotropin-releasing hormone (GnRH) on the proliferation of ovarian granulosa cells (GCs) and the development of follicles in geese (Anser cygnoides) by colorimetry and ethynyl-2'-deoxyuridine (EdU) cell proliferation assays, in which primary GCs were treated with different concentrations of GnRH agonist (alarelin acetate) and an antagonist (cetrorelix acetate). Differently expressed genes (DEGs) were identified by RNA-sequencing and validated by quantitative reverse transcription polymerase chain reaction (RT-qPCR) and Western blotting. 2. The EdU assays showed that the proliferation of GCs was affected by the GnRH agonist and antagonist in a dose-dependent manner. The effect of treatment on cell proliferation was statistically significant at the concentrations of 10^-5 mol/l alarelin and 1 mg/l cetrorelix acetate. A total of 134 DEGs (76 downregulated and 58 upregulated for alarelin treatment) and 226 DEGs (90 downregulated and 136 upregulated for cetrorelix) were identified by RNA-sequencing analysis, respectively. Enrichment analysis indicated that DEGs were enriched in the GO terms of cell-cell signalling and cell junctions. The pathways that regulate the development of follicles were identified, including the biological progress of cAMP accumulation, ovulation cycle and vasculature that are essential to follicular selection. 3. The results suggested that GnRH might directly regulate GC proliferation via autocrine or paracrine pathways related to cell junctions. In particular, it was confirmed that the mRNA and protein expression levels of the oestrogen receptor 2 (ESR2) gene, a negative transcription factor involved in follicular maturation and ovulation, were affected by GnRH agonist or antagonist in GCs. 4. In conclusion, GnRH might play an important role in follicular development by changing the expression of genes that participate in cAMP accumulation, ovulation cycle and cell junctions in ovarian GCs.

Expression and Contribution of NLRP3 Inflammasome During the Follicular Development Induced by PMSG

Follicular development and following ovulation induced by luteinizing hormone (LH) surge are critical for ovarian functions, but the molecular mechanism regulating ovarian ovulation attracts more attention and remains mainly unknown. Recent researches on the nucleotide leukin rich polypeptide 3 (NLRP3) inflammasome shred light on it. Given pregnant mare serum gonadotropin (PMSG) can not only trigger the follicular development, but also induce the following ovulation, the present study therefore examined that expression and localization of NLRP3 inflammasome through immunohistochemistry and Western blotting during the follicular development induced by PMSG. The results showed expressions of NLRP3 and the adaptor protein apoptosis-associated speck-like protein (ASC) significantly increased in the outside of intrafollicular fluid, further analysis found that caspase-1 was activated and IL-1β production was also upregulated after 52 h-treatment of PMSG. Furthermore, a significant increase of ovulation-related genes, hypoxia inducible factor (HIF)-1α and endothelin (ET)-1, was found after 52 h-treatment of PMSG. To our knowledge, it is the first time to clearly indicated the activation of NLRP3 inflammasome may contribute to the ovulation of PMSG-treated ovaries, which will help to further clarify the ovulatory mechanism in mammals.

Ovulation: Parallels With Inflammatory Processes

The midcycle surge of LH sets in motion interconnected networks of signaling cascades to bring about rupture of the follicle and release of the oocyte during ovulation. Many mediators of these LH-induced signaling cascades are associated with inflammation, leading to the postulate that ovulation is similar to an inflammatory response. First responders to the LH surge are granulosa and theca cells, which produce steroids, prostaglandins, chemokines, and cytokines, which are also mediators of inflammatory processes. These mediators, in turn, activate both nonimmune ovarian cells as well as resident immune cells within the ovary; additional immune cells are also attracted to the ovary. Collectively, these cells regulate proteolytic pathways to reorganize the follicular stroma, disrupt the granulosa cell basal lamina, and facilitate invasion of vascular endothelial cells. LH-induced mediators initiate cumulus expansion and cumulus oocyte complex detachment, whereas the follicular apex undergoes extensive extracellular matrix remodeling and a loss of the surface epithelium. The remainder of the follicle undergoes rapid angiogenesis and functional differentiation of granulosa and theca cells. Ultimately, these functional and structural changes culminate in follicular rupture and oocyte release. Throughout the ovulatory process, the importance of inflammatory responses is highlighted by the commonalities and similarities between many of these events associated with ovulation and inflammation. However, ovulation includes processes that are distinct from inflammation, such as regulation of steroid action, oocyte maturation, and the eventual release of the oocyte. This review focuses on the commonalities between inflammatory responses and the process of ovulation.

Coordination of Ovulation and Oocyte Maturation: A Good Egg at the Right Time

Ovulation is the appropriately timed release of a mature, developmentally competent oocyte from the ovary into the oviduct, where fertilization occurs. Importantly, ovulation is tightly linked with oocyte maturation, demonstrating the interdependency of these two parallel processes, both essential for female fertility. Initiated by pituitary gonadotropins, the ovulatory process is mediated by intrafollicular paracrine factors from the theca, mural, and cumulus granulosa cells, as well as the oocyte itself. The result is the induction of cumulus expansion, proteolysis, angiogenesis, inflammation, and smooth muscle contraction, which are each required for follicular rupture. These complex intercellular communication networks and the essential ovulatory genes have been well defined in mouse models and are highly conserved in primates, including humans. Importantly, recent discoveries in regulation of ovulation highlight new areas of investigation.

Association study of frameshift and splice variant polymorphisms with risk of idiopathic recurrent pregnancy loss

Recurrent pregnancy loss (RPL) is defined as ≥2 consecutive pregnancy losses, and can be caused by various factors, including genetics, chromosomal abnormalities, thrombophilia, immune disorders, nutritional factors, environmental factors, psychological stress or maternal infections; however, as many as 50% of RPL cases are idiopathic. In the present study, the role of genetic polymorphisms in RPL was investigated. Four gene polymorphisms were selected by whole exome sequencing, including membrane spanning 4‑domains A14 (MS4A14)D>I (rs3217518), solute carrier family 2 member 7 (SLC2A7)D>I (rs60746313), pregnancy specific β‑1‑glycoprotein 9 (PSG9)C>T (rs3746297) and ATP binding cassette subfamily B member 5 (ABCB5)C>G (rs17143187), and the aim was to investigate their association with RPL in Korean women. Genotyping was performed using polymerase chain reaction‑restriction fragment length polymorphism assay. Allele combination analysis revealed that the four‑allele combination I‑D‑T‑G, (MS4A14/SLC2A7/PSG9/ABCB5) was associated with a decreased risk for RPL. Interaction analysis demonstrated that the following genotypes: MS4A14 DI+II, SLC2A DI+II and ABCB 5 CG+GG, were associated with a prothrombin time ≥12 sec and with RPL risk. It may be concluded that the four gene polymorphisms do not affect RPL individually, but are associated with RPL when in combination with other genes or blood coagulation factors. Notably, the MS4A14 I allele, with a prothrombin time ≥12 sec, may be a potential biomarker for diagnosis, prevention and prognosis of RPL.

Association between vascular endothelial growth factor promoter polymorphisms and the risk of recurrent implantation failure

The objective of the present study was to investigate the association between recurrent implantation failure (RIF) and vascular endothelial growth factor (VEGF) gene polymorphisms that are associated with various female infertility disorders. A total of 116 women diagnosed with RIF and 218 control subjects were genotyped for the VEGF -2578C>A, -1154G>A, -634C>G and 936C>T polymorphisms using a polymerase chain reaction-restriction fragment length polymorphism assay. The VEGF -2578AA genotype was associated with an increased prevalence (≥4) of RIF [adjusted odds ratio (AOR)=2.77; 95% confidence interval (CI)=1.10-7.02; P=0.031], whereas the VEGF -634CG+GG genotype was associated with an increased incidence of total RIF (AOR=2.03; 95% CI=1.02-4.05; P=0.044) and ≥4 RIF (AOR=3.16; 95% CI=1.19-8.37; P=0.021). The results of the haplotype analysis indicated that -2578A/-1154A/-634G/936C (AOR=1.76; 95% CI=1.03-3.00; P=0.040 for total RIF and AOR=2.11; 95% CI=1.12-3.97; P=0.021 for ≥4 RIF) was associated with the occurrence of RIF. In addition, it was revealed that there was a significant difference in serum prolactin level associated with the VEGF -634C>G polymorphism (P=0.013). Therefore the findings of the present study indicate that the VEGF -2578AA genotype, -634G allele and -2578A/-1154A/-634G/936C haplotype may be genetic markers for susceptibility to RIF. However, further studies on VEGF promoter polymorphisms that include an independent randomized-controlled population are required to confirm these results.

Current status of the role of endothelins in regulating ovarian follicular function: A review

Endothelins (EDN) are a group of vasoactive 21 amino acid peptides reported to play roles in steroidogenesis, folliculogenesis, and ovulation. EDN1, EDN2 and EDN3 have all been shown to affect granulosa cell (GC) function in a variety of mammalians species. Herewithin, the role of EDN in regulating steroidogenesis and ovarian follicular development is reviewed, focusing on the localization and function of EDN and their receptors in ovarian follicular function emphasizing species differences. For example, in single ovulating species such as humans and cattle, in the presence of trophic hormones such as FSH and IGF1, EDN1 and EDN2 significantly inhibited GC estradiol production in 2 of 4 studies, while no effect was observed for GC progesterone production in 2 of 4 studies. In contrast, EDN1 exhibited inhibitory effects on progesterone production by GC in 3 of 3 studies in pigs and 3 of 4 studies in rats. Also, EDN1 inhibited GC estradiol production in 4 of 5 studies in rats. Altogether, these results indicate that EDN are produced by ovarian follicles and are involved in the regulation of steroidogenesis of GC of several mammalian species including humans, cattle, pigs and rats, but that these effects may vary with species and culture condition.

Single nucleotide polymorphisms at miR-146a/196a2 and their primary ovarian insufficiency-related target gene regulation in granulosa cells

MicroRNAs post-transcriptionally regulate gene expression in animals and plants. The aim of this study was to identify new target genes for microRNA polymorphisms (miR-146aC>G and miR-196a2T>C) in primary ovarian insufficiency (POI). We cloned and transfected miR-146aC>G and miR-196a2T>C into human granulosa cells and used microarrays and qPCR-arrays to examine the changes in the messenger RNA expression profile. We show miR-146aC>G and miR-196a2T>C change the mRNA expression patterns in granulosa cell. In each case, mRNAs were up or down-regulated after treatments with miR-146a C or G and miR-196a2 T or C. We found that miR-146a led to a significantly altered regulation of the mRNA levels of FOXO3, FOXL2 and CCND2 compared to controls. We also found that the polymorphisms of miR-146a led to a significantly altered regulation of CCND2 and FOXO3. Our results suggest that miR-146aC>G and miR-196a2T>C can regulate the levels of many of their target transcripts. In addition, specific target genes of miR-146aC>G polymorphisms may be involved in granulosa cell regulation.

Granulosa cell endothelin-2 expression is fundamental for ovulatory follicle rupture

Ovulation is dependent upon numerous factors mediating follicular growth, vascularization, and ultimately oocyte release via follicle rupture. Endothelin-2 (EDN2) is a potent vasoconstrictor that is transiently produced prior to follicle rupture by granulosa cells of periovulatory follicles and induces ovarian contraction. To determine the role of Edn2 expression, surgical transplant and novel conditional knockout mice were super-ovulated and analyzed. Conditional knockout mice utilized a new iCre driven by the Esr2 promoter to selectively remove Edn2. Follicle rupture and fertility were significantly impaired in the absence of ovarian Edn2 expression. When ovaries of Edn2KO mice were transplanted in wild type recipients, significantly more corpora lutea containing un-ovulated oocytes were present after hormonal stimulation (1.0 vs. 5.4, p = 0.010). Following selective ablation of Edn2 in granulosa cells, Esr2-Edn2KO dams had reduced oocytes ovulated (3.8 vs. 16.4 oocytes/ovary) and smaller litters (4.29 ± l.02 vs. 8.50 pups/dam). However, the number of pregnancies per pairing was not different and the reproductive axis remained intact. Esr2-Edn2KO ovaries had a higher percentage of antral follicles and fewer corpora lutea; follicles progressed to the antral stage but many were unable to rupture. Conditional loss of endothelin receptor A in granulosa cells also decreased ovulation but did not affect fecundity. These data demonstrate that EDN2-induced intraovarian contraction is a critical trigger of normal ovulation and subsequent fecundity.

Association of breast cancer-related microRNA polymorphisms with idiopathic primary ovarian insufficiency

OBJECTIVE

The aim of our study was to investigate whether breast cancer-related microRNA polymorphisms are associated with primary ovarian insufficiency (POI) risk.

METHODS

Four breast cancer-related microRNA polymorphisms (miR-27aA > G [rs895819], miR-135bC > T [rs74141216], miR-423C > A [rs6505162], and miR-608G > C [rs4919510]) were genotyped in 136 women with idiopathic POI and 224 controls of Korean ethnicity using polymerase chain reaction-restriction fragment length polymorphism analysis. Differences in genotype frequencies between cases and controls were compared. Odds ratios and 95% CIs were determined as measures of the strength of association between genotype and POI.

RESULTS

Two haplotypes (G-C-A-G and A-T-C-C) of miR-27a/miR-135b/miR-423/miR-608 were associated with increased POI risk. The haplotypes G-A-G of miR-27a/miR-423/miR-608 and A-T-C of miR-27a/miR-135b/miR-608 were associated with higher POI risk, whereas the G-T haplotype of miR-27a/miR-135b was associated with decreased POI risk. The association between POI risk and the G-A-G haplotype of miR-27a/miR-423/miR-608 remained significant after false discovery rate correction for multiple comparisons. The combined genotypes AA/CT/CC/CC, AG/CC/CA/GC, GG/CC/CC/CC, and GG/CC/CA/GG of miR-27a/miR-135b/miR-423/miR-608 were also associated with higher POI risk. Increased POI risk was observed in combined genotypes GG/CC/GG of miR-27a/miR-135b/miR-608; AA/CC/GC, AG/CA/GC, GG/CC/GG, GG/CC/CC, and GG/CA/GG of miR-27a/miR-423/miR-608; and GG/GG of miR-27a/miR-608; however, these associations were not significant after false discovery rate correction. None of the four microRNA polymorphisms alone was associated with POI risk.

CONCLUSIONS

Our data suggest that breast cancer-related microRNA polymorphisms, including miR-27aA > G, miR-423C > A, and miR-608G > C, are associated with increased POI risk via interactions between miR-27aG, miR-423A, and miR-608G variants. However, our results should be interpreted cautiously because of our small sample size and the low statistical power of our study design.

Expression and functional implications of luteal endothelins in pregnant and non-pregnant dogs

Luteal development is regulated by many locally produced mediators, e.g., prostaglandins and angiogenic factors. However, the role and function of vasoactive factors in the canine corpus luteum (CL) remain largely unknown. Consequently, expression of the endothelin (ET) receptors-A and -B (ETA and ETB, revealing vasoconstriction and vasodilator properties respectively), the ET-converting enzyme (ECE1) and ET1, -2 and -3 were investigated in CL from non-pregnant dogs (days 5, 15, 25, 35, 45 and 65 post-ovulation), and at selected stages of pregnancy (pre-implantation, post-implantation, mid-gestation), and during normal and antigestagen-inducedprepartumluteolysis/abortion. The interrelationship between PGE2 and the ET system was investigated in PGE2-treated canine primary lutein cells from early CL.ET1did not change significantly over time;ET2,ECE1andETBwere elevated in early CL and were downregulated towards the mid/late-luteal phase. Theprepartumincrease ofET2was significant.ET3increased gradually, and was highest in late CL and/or atprepartumluteolysis.ETAremained constant until the late CL phase and increased only duringprepartumluteolysis. ET1 was localized to the luteal cells, andET2,ET3and ETA to vascular endothelium. ECE1 and ETB were detected at both locations. Except for upregulatedET1and lack of effect onET2,antigestagen applied to mid-pregnant dogs evoked similar changes to those observed during normal luteolysis. PGE2 upregulatedETBin treated cells;ETAandET1remained unaffected, andET2decreased. A modulatory role of the ETs in canine CL, possibly in association with other factors (e.g., PGE2 and progesterone receptor), is strongly indicated.

Loss of function of endothelin-2 leads to reduced ovulation and CL formation

Endothelin-2 (EDN2), a potent vasoconstrictive peptide, is transiently produced by periovulatory follicles at the time of ovulation when corpus luteum (CL) formation begins. EDN2 induces contraction of ovarian smooth muscles ex vivo via an endothelin receptor A-mediated pathway. In this study, we aimed to determine if EDN2 is required for normal ovulation and subsequent CL formation in?vivo. In the ovaries of a mouse model that globally lacks the Edn2 gene (Edn2 knockout mouse; Edn2KO), histology showed that post-pubertal Edn2KO mice possess follicles of all developmental stages, but no corpora lutea. When exogenous gonadotropins were injected to induce super-ovulation, Edn2KO mice exhibited significantly impaired ovulation and CL formation compared to control littermates. Edn2KO ovaries that did ovulate in response to gonadotropins did not contain histologically and functionally identifiable CL. Intra-ovarian injection of EDN2 peptide results suggest partial induction of ovulation in Edn2KO mice. Endothelin receptor antagonism in wild type mice similarly disrupted ovulation, CL formation, and progesterone secretion. Overall, this study suggests that EDN2 is necessary for normal ovulation and CL formation.

Association of five common polymorphisms in the plasminogen activator inhibitor-1 gene with primary ovarian insufficiency

OBJECTIVE

To investigate the association between potentially functional plasminogen activator inhibitor-1 (PAI-1) genetic polymorphisms and primary ovarian insufficiency (POI).

DESIGN

Case-control study.

SETTING

Urban university-based hospital.

PATIENT(S)

A cohort of 137 POI patients and 227 controls.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Genotyping of five PAI-1 polymorphisms (-844G>A [rs2227631], -675 4G/5G [rs1799889], 43G>A (Ala>Thr) [rs6092], 9785G>A [rs2227694], and 11053T>G [rs7242]) was assessed by polymerase chain reaction-restriction fragment length polymorphism assay.

RESULT(S)

PAI-1 polymorphisms 9785GA+AA, -844A/9785A, 4G/9785A, and 9785A/11053G were associated with POI occurrence. Moreover, -844GA+AA and 11053TG+GG were associated with lower serum E2 levels in controls.

CONCLUSION(S)

We have identified an association between five PAI-1 polymorphisms and POI occurrence. However, the mechanism underlying the function of these polymorphisms in POI remains to be determined. Further studies are needed to improve understanding of the roles of PAI-1 polymorphisms and genes in related pathways, using a larger and more heterogeneous cohort.

Association of inhibin α gene promoter polymorphisms with risk of idiopathic primary ovarian insufficiency in Korean women

OBJECTIVE

The aim of this study was to investigate whether two polymorphisms in the promoter region of inhibin alpha (INHA) are associated with risk of idiopathic primary ovarian insufficiency (POI) in Korean women, which is a controversial topic.

STUDY DESIGN

We genotyped the INHA polymorphisms c.-16C>T (rs35118453) and c.-124A>G (rs11893842) of 136 POI patients and 225 controls in Korean women by polymerase chain reaction and restriction fragment length polymorphism analysis. We then compared differences in genotype and allele frequencies (AF) of the polymorphisms between the two groups to determine odds ratios (OR) and 95% confidence intervals (CI) as measures of the strength of association between genotype and POI.

RESULTS

There were no significant differences in genotype or AF of the polymorphisms between the POI patients and controls. Haplotype analysis revealed that the T-G haplotype of the two variant alleles was more frequent in POI patients than in the controls (OR=1.630, 95% CI=1.081-2.457). Combination genotype analysis showed that the CT+TT/GG genotype frequency was higher in POI patients than in the controls (OR=2.414, 95% CI=1.190-4.895).

CONCLUSIONS

We provide evidence to suggest that when the two variant alleles are combined, the c.-16C>T and c.-124A>G polymorphisms are associated with increased POI risk in Korean women. We postulate that interactions between the INHA polymorphisms may affect POI risk.

The distinguishing cellular and molecular features of the endometriotic ovarian cyst: from pathophysiology to the potential endometrioma-mediated damage to the ovary

BACKGROUND

Clinical data suggest that the presence of an ovarian endometrioma may cause per se damage to the surrounding otherwise healthy ovarian tissue. However, the basic research has so far done a limited job in trying to understand the potential detrimental effect of an endometrioma presence in the context of the ovarian physiology. We have reviewed the literature with the aim of characterizing the pathophysiology of the endometrioma focusing mostly on factors and mechanisms potentially affecting the surrounding, otherwise normal, ovarian tissue.

METHODS

Comprehensive searches of PUBMED were conducted to identify human studies published from 1991 to 2013 in the English language on the cellular and molecular characterization of the various endometrioma components.

RESULTS

An endometrioma contains free iron, reactive oxygen species (ROS), proteolytic enzymes and inflammatory molecules in concentrations from tens to hundreds of times higher than those present in peripheral blood or in other types of benign cysts. The cyst fluid causes substantial changes in the endometriotic cells that it baths from gene expression modifications to genetic mutations The physical barrier between the cyst contents and the normal ovarian tissue is a thin wall composed of the ovarian cortex itself or fibroreactive tissue. ROS potentially permeating the surrounding tissues and proteolytic substances degrading the adjacent areas are likely to cause the substitution of normal ovarian cortical tissue with fibrous tissue in which the cortex-specific stroma is reduced. The fibrosis is associated with smooth muscle metaplasia and followed by follicular loss and intraovarian vascular injury. Follicular density in tissue surrounding the endometriotic cyst was consistently shown to be significantly lower than in healthy ovaries but this pathological change does not appear to be caused by the stretching of surrounding tissues owing to the presence of a cyst.

CONCLUSIONS

There is sufficient molecular, histological and morphological evidence, in part deriving from knowledge of the pathophysiology, to support a deleterious effect of the endometrioma on the adjacent ovarian cortical tissue, independent of the mere mechanical stretching owing to its size.

Blockade of endothelin receptors with bosentan limits ischaemia/reperfusion-induced injury in rat ovaries

OBJECTIVE

To investigate the role of endothelin receptors in ovarian ischaemia/reperfusion (I/R) injury in rats using the endothelin receptor antagonist bosentan.

STUDY DESIGN

Group 1: sham operation; Group 2: sham operation and bosentan 60 mg/kg; Group 3: bilateral ovarian ischaemia; Group 4: 3-h period of ischaemia followed by 3h of reperfusion; Groups 5 and 6: bosentan 30 and 60 mg/kg, respectively, with bilateral ovarian ischaemia applied 30 min later; the bilateral ovaries were removed after 3h of ischaemia; Groups 7 and 8: 3h of bilateral ovarian ischaemia was applied, with bosentan 30 and 60 mg/kg, respectively, administered 2.5h after the induction of ischaemia; following the 3-h period of ischaemia, 3h of reperfusion was applied, after which the ovaries were removed.

RESULTS

Ischaemia and I/R decreased superoxide dismutase (SOD) activity and the level of glutathione (GSH) in ovarian tissue, but increased the level of malondialdehyde (MDA) significantly compared with the sham operation group. Bosentan 30 and 60 mg/kg before ischaemia and I/R decreased the MDA level and increased SOD activity and the GSH level in the experimental groups. The serum levels of the inflammatory cytokines interleukin (IL)-1β, IL-6 and tumour necrosis factor-α were also measured in the I/R injury model in rat ovaries. The levels of these cytokines were significantly higher in the ischaemia and I/R groups compared with the sham operation and sham operation plus bosentan groups. The histopathological findings also demonstrated the protective role of bosentan against I/R-induced injury in rat ovaries.

CONCLUSION

Administration of bosentan protects the ovaries against oxidative damage and I/R-induced injury.

Early progress in epigenetic regulation of endothelin pathway genes

Control of gene transcription is a major regulatory determinant for function of the endothelin pathway. Epigenetic mechanisms act on tissue-specific gene expression during development and in response to physiological stimuli. Most of the limited evidence available on epigenetic regulation of the endothelin pathway focuses on the EDN1 and EDNRB genes. Examination of whole genome databases suggests that both genes are influenced by histone modifications and DNA methylation. This interpretation is supported by studies directed at detecting epigenetic action on the two genes. The clearest illustration of epigenetic factors altering endothelin signalling is DNA methylation-associated EDNRB silencing during tumourigenesis. This review summarizes our current understanding of epigenetic regulation of the endothelin pathway genes. LINKED ARTICLES This article is part of a themed section on Endothelin. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2013.168.issue-1.

Tumor necrosis factor-alpha promoter polymorphisms are associated with idiopathic primary ovarian insufficiency in Korean women

OBJECTIVE

To investigate the possible association between primary ovarian insufficiency (POI) and TNF-α gene polymorphisms in Korean women.

DESIGN

Case-control study.

SETTING

An urban university-based hospital in South Korea.

PATIENT(S)

A cohort of 135 Korean POI patients and 236 controls.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

We analyzed TNF-α gene variants of all participants using the polymerase chain reaction-restriction fragment length polymorphism assay.

RESULT(S)

The TNF-α -1031TC+CC, -238GA+AA, -1031TC+CC/-308GG, -1031TT/-308GA+AA, -1031TC+CC/-238GA+AA, and -308GG/-238GA+AA genotypes were significantly more frequent in POI patients than in controls. Among the haplotypes for the three TNF-α loci, the -1031C/-308G/-238A haplotype was more frequent in POI patients than in controls and conferred POI susceptibility. In analyses of two loci, the -1031T/-308A, -1031C/-308G, -1031C/-238A, and -308G/-238A haplotypes were more frequent in POI patients.

CONCLUSION(S)

The TNF-α -1031C and -238A alleles had strong association with POI. The TNF-α -308A allele showed limited significance for POI risk with the presence of the -1031T allele. Our data suggest that the minor alleles of TNF-α promoter polymorphisms may increase POI risk in Korean women.

Association of miR-146aC>G, miR-196a2T>C, and miR-499A>G polymorphisms with risk of premature ovarian failure in Korean women

We investigated whether microRNA (miRNA) polymorphisms (miR-146aC>G, miR-196a2T>C, and miR-499A>G) confer risk of premature ovarian failure (POF) in Korean women. DNA samples from 136 patients with POF and 234 controls were genotyped for the 3 miRNA single-nucleotide polymorphisms by polymerase chain reaction-restriction fragment length polymorphism. The miR-146aCG/miR-196a2TC combined genotype was less frequent in patients than in controls (P < .05), conferring less susceptibility. Using haplotype-based multifactor dimensionality reduction analysis, the C-C-A and G-T-A inferred haplotypes (miR-146a/miR-196a2/miR-499) were less frequent in patients, suggesting protective effects (P < .05 for each), whereas the C-T-A and G-C-A haplotypes were more frequent in patients (P < .05 for each). The C-T and G-C haplotypes (miR-146a/miR-196a2) were more frequent in patients, whereas the C-C and G-T haplotypes were less frequent in patients (P < .05 for each). However, none of the 3 miRNA polymorphisms alone was associated with POF risk. Our findings suggest that putative gene-gene interaction between miR-146 and miR-196a2 may be involved in POF development.

Altered endothelin expression in granulosa-lutein cells of women with polycystic ovary syndrome

AIMS

To examine the levels of endothelin system components in granulosa lutein cells (GLCs) of women with PCOS and compare them to normally ovulating women undergoing In Vitro Fertilization (IVF). Polycystic ovary syndrome (PCOS) is one of the most common endocrine-metabolic disorders in women of reproductive age. Endothelins are locally produced by endothelial and granulosa cells of the preovulatory follicle. Abnormal expression or production of endothelins may be a contributing factor in PCOS pathogenesis.

MAIN METHODS

Follicular aspirates containing GLCs were obtained from PCOS and normally ovulating patients undergoing oocyte retrieval during the IVF cycle. RNA was extracted and endothelin system components were quantified using real-time PCR. GLCs were cultured in basal media for 7 days, and then challenged with various luteinizing agents (luteinizing hormone, hCG, or forskolin) for 24 h.

KEY FINDINGS

In GLCs from women with PCOS, Endothelin-1 mRNA expression was elevated (2.2-fold) as compared with normally ovulating women, whereas endothelin-2 mRNA was reduced (1.8-fold). ET receptors and endothelin-converting enzyme showed the same expression levels in the two groups. In vitro modeling showed that although the steroidogenic response was preserved in GLC, endothelin expression levels were not exhibited in vitro in their original pattern.

SIGNIFICANCE

Dysregulation of ovarian endothelin expression may induce a pathologic ovulation pattern characteristic of PCOS.