Intraovarian activins are required for female fertility

New aspects of activin biology in epididymal function and immunopathology

The activins (A and B) and their binding protein, follistatin, play crucial roles in development, immunoregulation and inflammation throughout the body. In the male reproductive tract of the mouse, activin A and B production is largely confined to the initial segment and proximal caput of the epididymis and the efferent ducts, under normal conditions, with very low expression in the corpus, cauda and vas deferens. However, activin A protein is present throughout the epididymis and vas deferens and is largely associated with the epithelium and interstitial macrophages. Conversely, the activin-binding protein follistatin is produced in the distal epididymis, with very high expression in the vas deferens. Activin activity in the distal tract is inhibited by follistatin, and the activin-follistatin balance is important for regulating coiling of the duct during epididymal development. In further experiments, as described in this report, in situ hybridisation was used to localise activin A mRNA principally to cells in the periductal zone and interstitium in the efferent ducts and proximal caput. Activin B mRNA, on the other hand, was localised to periductal cells in the efferent ducts and proximal epididymis and, most notably, to epithelial cells in the initial segment. Activin A is implicated in the regulation of mononuclear phagocyte function and immune responses in the caput and stimulates the expression of the key immunoregulatory protein, indoleamine 2,3-dioxygenase in this region. Activin A production in the corpus and cauda increases dramatically during bacterial epididymitis in mice, promoting inflammation and fibrosis and causing damage to the epithelium and obstruction of the epididymal duct. Consequently, it appears that the activin-follistatin axis is crucial for maintaining normal epididymal structure and function, but disruption of this balance during inflammation has deleterious effects on male fertility. Follistatin has therapeutic potential in ameliorating the proinflammatory and profibrotic effects of activins.

Gene Function is a Driver of Activin Signaling Pathway Evolution Following Whole-Genome Duplication in Rainbow Trout (Oncorhynchus mykiss)

The genomes of plant and animal species are influenced by ancestral whole-genome duplication (WGD) events, which have profound impacts on the regulation and function of gene networks. To gain insight into the consequences of WGD events, we characterized the sequence conservation and expression patterns of ohnologs in the highly duplicated activin receptor signaling pathway in rainbow trout (RBT). The RBT activin receptor signaling pathway is defined by tissue-specific expression of inhibitors and ligands and broad expression of receptors and Co-Smad signaling molecules. Signaling pathway ligands exhibited shared expression, while inhibitors and Smad signaling molecules primarily express a single dominant ohnolog. Our findings suggest that gene function influences ohnolog evolution following duplication of the activin signaling pathway in RBT.

Neutrophil-derived Activin-A moderates their pro-NETotic activity and attenuates collateral tissue damage caused by Influenza A virus infection

Background

Pre-neutrophils, while developing in the bone marrow, transcribe the Inhba gene and synthesize Activin-A protein, which they store and release at the earliest stage of their activation in the periphery. However, the role of neutrophil-derived Activin-A is not completely understood.

Methods

To address this issue, we developed a neutrophil-specific Activin-A-deficient animal model (S100a8-Cre/Inhba fl/fl mice) and analyzed the immune response to Influenza A virus (IAV) infection. More specifically, evaluation of body weight and lung mechanics, molecular and cellular analyses of bronchoalveolar lavage fluids, flow cytometry and cell sorting of lung cells, as well as histopathological analysis of lung tissues, were performed in PBS-treated and IAV-infected transgenic animals.

Results

We found that neutrophil-specific Activin-A deficiency led to exacerbated pulmonary inflammation and widespread hemorrhagic histopathology in the lungs of IAV-infected animals that was associated with an exuberant production of neutrophil extracellular traps (NETs). Moreover, deletion of the Activin-A receptor ALK4/ACVR1B in neutrophils exacerbated IAV-induced pathology as well, suggesting that neutrophils themselves are potential targets of Activin-A-mediated signaling. The pro-NETotic tendency of Activin-A-deficient neutrophils was further verified in the context of thioglycollate-induced peritonitis, a model characterized by robust peritoneal neutrophilia. Of importance, transcriptome analysis of Activin-A-deficient neutrophils revealed alterations consistent with a predisposition for NET release.

Conclusion

Collectively, our data demonstrate that Activin-A, secreted by neutrophils upon their activation in the periphery, acts as a feedback mechanism to moderate their pro-NETotic tendency and limit the collateral tissue damage caused by neutrophil excess activation during the inflammatory response.

Endometrial TGFβ signaling fosters early pregnancy development by remodeling the fetomaternal interface

The endometrium is a unique and highly regenerative tissue with crucial roles during the reproductive lifespan of a woman. As the first site of contact between mother and embryo, the endometrium, and its critical processes of decidualization and immune cell recruitment, play a leading role in the establishment of pregnancy, embryonic development, and reproductive capacity. These integral processes are achieved by the concerted actions of steroid hormones and a myriad of growth factor signaling pathways. This review focuses on the roles of the transforming growth factor β (TGFβ) pathway in the endometrium during the earliest stages of pregnancy through the lens of immune cell regulation and function. We discuss how key ligands in the TGFβ family signal through downstream SMAD transcription factors and ultimately remodel the endometrium into a state suitable for embryo implantation and development. We also focus on the key roles of the TGFβ signaling pathway in recruiting uterine natural killer cells and their collective remodeling of the decidua and spiral arteries. By providing key details about immune cell populations and TGFβ signaling within the endometrium, it is our goal to shed light on the intricate remodeling that is required to achieve a successful pregnancy.

FOXG1 is involved in mouse ovarian functions and embryogenesis

TGF-β superfamily has long been demonstrated to be essential for folliculogenesis and luteinization. Forkhead box G1 (FOXG1, also known as BF1), a member of the FOX family and an inhibitor of TGF-β signaling pathway, is a nucleocytoplasmic transcription factor that is essential for forebrain development. FOXG1 is involved in neurodevelopment and cancer pathology, however, little is known about the role of FOXG1 in reproduction. In this study, the spatiotemporal expression pattern of FOXG1 was examined during early mouse oocyte and embryonic development and its role during corpora luteum (CL) formation was further elucidated. The results showed that FOXG1 is localized in oocytes, theca cells (TCs) and CLs. After fertilization, FOXG1 is expressed at all stages during early embryogenesis, from zygotes to blastocysts. Following gonadotropin administration in immature mice, the expression of Foxg1 significantly increased along with steroidogenic genes, including Star, Hsd3β, Cyp11a1, as well as Cyp17a1 and Cyp19a1. The latter two first increased after pregnant mare serum gonadotropin stimulation, then decreased in response to hCG treatment. In addition, silencing of Foxg1 significantly reduced the concentration of testosterone and estrogen in cultured primary granulosa cells (GCs) and TCs (P < 0.05). Mechanistic studies demonstrated that the expression level of genes that are critical in estrogen synthesis were significantly reduced after Foxg1 silencing, including Cyp17a1 and Cyp19a1. In conclusion, FOXG1 is expressed in a stage-specific manner during folliculogenesis and embryogenesis and exerts a regulatory influence on testosterone and estrogen synthesis.

Targeted Deletion of Mitofusin 1 and Mitofusin 2 Causes Female Infertility and Loss of Follicular Reserve

Mitochondria are dynamic organelles that regulate their size, shape, and morphology through mechanisms called fusion and fission, to continually adapt themselves to their bioenergetic environment. These mechanisms play a critical role to maintain the mitochondrial function under metabolic and environmental stress. Mitofusin 1 (MFN1) and mitofusin 2 (MFN2) are transmembrane GTPases that regulate mitochondrial fusion mechanism and are required for the maintenance of cellular homeostasis. In this study, we aimed to determine the role of mitofusins in female reproductive competence and senescence using a mouse model with oocyte-specific double deletion of Mfn1 and Mfn2, eliminating the potential functional redundancy of these two proteins. Oocyte-specific targeted double deletion of Mfn1 and Mfn2 in mice resulted in female infertility associated with impaired follicular development and oocyte maturation. It also resulted in altered mitochondrial dynamics and mitochondrial dysfunction. Lack of Mfn1 and Mfn2 in oocytes resulted in accelerated follicular depletion and impaired oocyte quality which are consistent with phenotype of reproductive aging.

Genetic analysis of activin/inhibin β subunits in zebrafish development and reproduction

Activin and inhibin are both dimeric proteins sharing the same β subunits that belong to the TGF-β superfamily. They are well known for stimulating and inhibiting pituitary FSH secretion, respectively, in mammals. In addition, activin also acts as a mesoderm-inducing factor in frogs. However, their functions in development and reproduction of other species are poorly defined. In this study, we disrupted all three activin/inhibin β subunits (βAa, inhbaa; βAb, inhbab; and βB, inhbb) in zebrafish using CRISPR/Cas9. The loss of βAa/b but not βB led to a high mortality rate in the post-hatching stage. Surprisingly, the expression of fshb but not lhb in the pituitary increased in the female βA mutant together with aromatase (cyp19a1a) in the ovary. The single mutant of βAa/b showed normal folliculogenesis in young females; however, their double mutant (inhbaa-/-;inhbab-/-) showed delayed follicle activation, granulosa cell hypertrophy, stromal cell accumulation and tissue fibrosis. The ovary of inhbaa-/- deteriorated progressively after 180 dpf with reduced fecundity and the folliculogenesis ceased completely around 540 dpf. In addition, tumor- or cyst-like tissues started to appear in the inhbaa-/- ovary after about one year. In contrast to females, activin βAa/b mutant males showed normal spermatogenesis and fertility. As for activin βB subunit, the inhbb-/- mutant exhibited normal folliculogenesis, spermatogenesis and fertility in both sexes; however, the fecundity of mutant females decreased dramatically at 270 dpf with accumulation of early follicles. In summary, the activin-inhibin system plays an indispensable role in fish reproduction, in particular folliculogenesis and ovarian homeostasis.

Genome-wide association studies uncover genes associated with litter traits in the pig

Litter traits are critical economic variables in the pig industry as they represent a production indicator that can serve to determine sow fertility. In this study, a genome-wide association study on litter traits, including total number born (TNB), number born alive (NBA), litter birth weight (LBW), average birth weight (ABW), and piglet uniformity (PU), was carried out on two pig breeds (Yorkshire and Landrace). A total of 3 637 pigs of both breeds were genotyped using the GeneSeek GGP Porcine 50K SNP BeadChip. A mixed linear model (MLM) and fixed and random model circulating probability unification (FarmCPU) were employed in the genome-wide association studies for litter traits using combined data from the two pig breeds and data from each breed separately. Additionally, the heritability of traits was estimated using three methods-pedigree-based best linear unbiased prediction (PBLUP), genomic best linear unbiased prediction (GBLUP), and single-step best linear unbiased prediction (ssGBLUP)-and was found to lie between 0.065 and 0.1289, 0.0478 and 0.0938, 0.0793 and 0.0935, 0.1862 and 0.2163, and 0.0327 and 0.0419 for TNB, NBA, LBW, ABW, and PU, respectively. We also compared the genomic prediction accuracies and unbiasedness for litter traits of the three BLUP models. Our results indicated that the ssGBLUP method provided higher predictive accuracies and more rational unbiasedness compared with the PBLUP and GBLUP methodologies. Furthermore, based on their possible roles, eight candidate genes (INHBA, LEPR, HDHD2, CTNND2, RNF216, HMX1, PAPPA2, and NTN1) were identified as being linked with litter traits. In the middle of the test, these genes were found to be connected with pig metabolism and ovulation rate. Our results provide the insights into the genetic architecture of litter traits in pigs, and the potential single nucleotide polymorphisms (SNPs) and candidate genes identified may benefit economic profits in pig-breeding industry and contribute to improve litter traits.

Knockout of cyclin B1 in granulosa cells causes female subfertility

In mammalian cells, cyclin B1 plays a pivotal role in mitotic and meiotic progression. It has been reported that infertility occurs after disruption of cyclin B1 (Ccnb1) in male germ cells and oocytes. However, it remains to be elucidated whether the specific disruption of Ccnb1 in granulosa cells influences the reproductive activity of female mice. Amhr2 is expressed in granulosa cells (GCs) of the ovary. Here, we mated Ccnb1^Flox/Flox mice with a transgenic mouse strain expressing Amhr2-Cre to generate GC-specific Ccnb1 knockout mice. The results showed that Ccnb1 ^Flox/Flox, Amhr2-Cre (Ccnb1 cKO) mice were subfertile but had normal oocyte meiotic progress, spindle shape and protein levels of cohesin subunits REC8 and SMC3 on arm chromosomes during meiosis I. A further study found that 32.4% of oocytes from Ccnb1 cKO mice exhibited chromosome condensation and spindle disassembly after the first polar body extrusion and failed to undergo second meiosis, which was never found in oocytes from Ccnb1^Flox/Flox mice. In addition, the percentages of 2-cell embryos, morulas, and blastocysts in the Ccnb1 mutant group were all dramatically decreased compared to those in the Ccnb1^Flox/Flox group (39.2% vs. 86.8%, 26.0% vs. 85.0%, 19.1% vs. 85.8%, respectively). Therefore, GC-specific Ccnb1 deletion in mice could cause fewer and poor-quality blastocysts and subsequent subfertility, which plays an important role in understanding the function of cyclin B1 in reproduction.

Deletion of activin A in mesenchymal but not myeloid cells ameliorates disease severity in experimental arthritis

Objective

The aim of this study was to assess the extent and the mechanism by which activin A contributes to progressive joint destruction in experimental arthritis and which activin A-expressing cell type is important for disease progression.

Methods

Levels of activin A in synovial tissues were evaluated by immunohistochemistry, cell-specific expression and secretion by PCR and ELISA, respectively. Osteoclast (OC) formation was assessed by tartrat-resistant acid phosphatase (TRAP) staining and activity by resorption assay. Quantitative assessment of joint inflammation and bone destruction was performed by histological and micro-CT analysis. Immunoblotting was applied for evaluation of signalling pathways.

Results

In this study, we demonstrate that fibroblast-like synoviocytes (FLS) are the main producers of activin A in arthritic joints. Most significantly, we show for the first time that deficiency of activin A in arthritic FLS (ActβA^d/d ColVI-Cre) but not in myeloid cells (ActβA^d/d LysM-Cre) reduces OC development in vitro, indicating that activin A promotes osteoclastogenesis in a paracrine manner. Mechanistically, activin A enhanced OC formation and activity by promoting the interaction of activated Smad2 with NFATc1, the key transcription factor of osteoclastogenesis. Consistently, ActβA^d/d LysM-Cre hTNFtg mice did not show reduced disease severity, whereas deficiency of activin A in ColVI-Cre-expressing cells such as FLS highly diminished joint destruction reflected by less inflammation and less bone destruction.

Conclusions

The results highly suggest that FLS-derived activin A plays a crucial paracrine role in inflammatory joint destruction and may be a promising target for treating inflammatory disorders associated with OC formation and bone destruction like rheumatoid arthritis.

Ovarian Transcriptomic Analysis of Ninghai Indigenous Chickens at Different Egg-Laying Periods

Egg production is an essential indicator of poultry fertility. The ovary is a crucial organ involved in egg production; however, little is known about the key genes and signaling pathways involved in the whole egg-laying cycle of hens. In order to explore the mechanism of egg production at different stages of the egg-laying process, ovarian tissues from four chickens were randomly selected for transcriptome analysis at each of the three ages (145 d, 204 d, and 300 d in the early, peak, and late stages of egg laying). A total of 12 gene libraries were constructed, and a total of 8433 differential genes were identified from NH145d vs. NH204d, NH145d vs. NH300d and NH300d vs. NH204d (Ninghai 145-day-old, Ninghai 204-day-old, and Ninghai 300-day-old), with 1176, 1653 and 1868 up-regulated genes, and 621, 1955 and 1160 down-regulated genes, respectively. In each of the two comparison groups, 73, 1004, and 1030 differentially expressed genes were found to be co-expressed. We analyzed the differentially expressed genes and predicted nine genes involved in egg production regulation, including LRP8, BMP6, ZP4, COL4A1, VCAN, INHBA, LOX, PTX3, and IHH, as well as several essential egg production pathways, such as regulation adhesion molecules (CAMs), calcium signaling pathways, neuroactive ligand–receptor interaction, and cytokine–cytokine receptor interaction. Transcriptional analysis of the chicken ovary during different phases of egg-lay will provide a useful molecular basis for study of the development of the egg-laying ovary.

Causal and Candidate Gene Variants in a Large Cohort of Women With Primary Ovarian Insufficiency

CONTEXT

A genetic etiology likely accounts for the majority of unexplained primary ovarian insufficiency (POI).

OBJECTIVE

We hypothesized that heterozygous rare variants and variants in enhanced categories are associated with POI.

DESIGN

The study was an observational study.

SETTING

Subjects were recruited at academic institutions.

PATIENTS

Subjects from Boston (n = 98), the National Institutes of Health and Washington University (n = 98), Pittsburgh (n = 20), Italy (n = 43), and France (n = 32) were diagnosed with POI (amenorrhea with an elevated follicle-stimulating hormone level). Controls were recruited for health in old age or were from the 1000 Genomes Project (total n = 233).

INTERVENTION

We performed whole exome sequencing (WES), and data were analyzed using a rare variant scoring method and a Bayes factor-based framework for identifying genes harboring pathogenic variants. We performed functional studies on identified genes that were not previously implicated in POI in a D. melanogaster model.

MAIN OUTCOME

Genes with rare pathogenic variants and gene sets with increased burden of deleterious variants were identified.

RESULTS

Candidate heterozygous variants were identified in known genes and genes with functional evidence. Gene sets with increased burden of deleterious alleles included the categories transcription and translation, DNA damage and repair, meiosis and cell division. Variants were found in novel genes from the enhanced categories. Functional evidence supported 7 new risk genes for POI (USP36, VCP, WDR33, PIWIL3, NPM2, LLGL1, and BOD1L1).

CONCLUSIONS

Candidate causative variants were identified through WES in women with POI. Aggregating clinical data and genetic risk with a categorical approach may expand the genetic architecture of heterozygous rare gene variants causing risk for POI.

INHBA transfection regulates proliferation, apoptosis and hormone synthesis in sheep granulosa cells

Inhibin subunit beta A (INHBA) participates in the synthesis of inhibin A, activin A and activin AB. Here we investigated the effect and molecular mechanism of INHBA on proliferation, apoptosis and hormone synthesis in sheep granulosa cells (GCs) using in vitro transfection. We first noticed that INHBA expression increased with follicle diameter and was widely distributed in ovarian tissue. The proliferation rate of GCs was significantly increased and decreased with overexpression and silence of INHBA, respectively, compared with the negative controls. INHBA transfection affected GC proliferation and apoptosis, regulating the expression of many cell cycle-related and apoptosis-related genes. INHBA overexpression significantly decreased activin and estradiol secretion while increasing inhibin and progesterone secretion. The expression of follicle-stimulating hormone beta subunit was significantly decreased and increased with INHBA overexpression and knockdown, respectively. Notably, silence of INHBA inhibited the expression of many transforming growth factor beta-related genes. Overall, the functional molecule of INHBA gene may be associated with follicular development via regulating proliferation, apoptosis and folliculogenesis-related hormone secretion of sheep GCs. In addition, our findings may contribute to a better understanding of the law of follicular development and thus improve the reproductive performance of female animals.

Local versus systemic control of bone and skeletal muscle mass by components of the transforming growth factor-β signaling pathway

Skeletal muscle and bone homeostasis are regulated by members of the myostatin/GDF-11/activin branch of the transforming growth factor-β superfamily, which share many regulatory components, including inhibitory extracellular binding proteins and receptors that mediate signaling. Here, we present the results of genetic studies demonstrating a critical role for the binding protein follistatin (FST) in regulating both skeletal muscle and bone. Using an allelic series corresponding to varying expression levels of endogenous Fst, we show that FST acts in an exquisitely dose-dependent manner to regulate both muscle mass and bone density. Moreover, by employing a genetic strategy to target Fst expression only in the posterior (caudal) region of the animal, we show that the effects of Fst loss are mostly restricted to the posterior region, implying that locally produced FST plays a much more important role than circulating FST with respect to regulation of muscle and bone. Finally, we show that targeting receptors for these ligands specifically in osteoblasts leads to dramatic increases in bone mass, with trabecular bone volume fraction being increased by 12- to 13-fold and bone mineral density being increased by 8- to 9-fold in humeri, femurs, and lumbar vertebrae. These findings demonstrate that bone, like muscle, has an enormous inherent capacity for growth that is normally kept in check by this signaling system and suggest that the extent to which this regulatory mechanism may be used throughout the body to regulate tissue mass may be more significant than previously appreciated.

Constitutive expression of Steroidogenic factor-1 (NR5A1) disrupts ovarian functions, fertility, and metabolic homeostasis in female mice

Steroid hormones regulate various aspects of physiology, from reproductive functions to metabolic homeostasis. Steroidogenic factor-1 (NR5A1) plays a central role in the development of steroidogenic tissues and their ability to produce steroid hormones. Inactivation of Nr5a1 in the mouse results in a complete gonadal and adrenal agenesis, absence of gonadotropes in the pituitary and impaired development of ventromedial hypothalamus, which controls glucose and energy metabolism. In this study, we set out to examine the consequences of NR5A1 overexpression (NR5A1+) in the NR5A1-positive cell populations in female mice. Ovaries of NR5A1+ females presented defects such as multi-oocyte follicles and an accumulation of corpora lutea. These females were hyperandrogenic, had irregular estrous cycles with persistent metestrus and became prematurely infertile. Furthermore, the decline in fertility coincided with weight gain, increased adiposity, hypertriglyceridemia, hyperinsulinemia, and impaired glucose tolerance, indicating defects in metabolic functions. In summary, excess NR5A1 expression causes hyperandrogenism, disruption of ovarian functions, premature infertility, and disorders of metabolic homeostasis. This NR5A1 overexpression mouse provides a novel model for studying not only the molecular actions of NR5A1, but also the crosstalk between endocrine, reproductive, and metabolic systems.

Deletion of Gremlin-2 alters estrous cyclicity and disrupts female fertility in mice

Members of the differential screening-selected gene aberrative in neuroblastoma (DAN) protein family are developmentally conserved extracellular binding proteins that antagonize bone morphogenetic protein (BMP) signaling. This protein family includes the Gremlin proteins, GREM1 and GREM2, which have key functions during embryogenesis and adult physiology. While BMPs play essential roles in ovarian follicle development, the role of the DAN family in female reproductive physiology is less understood. We generated mice null for Grem2 to determine its role in female reproduction in addition to screening patients with primary ovarian insufficiency for variants in GREM2. Grem2-/- mice are viable, but female Grem2-/- mice have diminished fecundity and irregular estrous cycles. This is accompanied by significantly reduced production of ovarian anti-Müllerian hormone (AMH) from small growing follicles, leading to a significant decrease in serum AMH. Surprisingly, as AMH is a well-established marker of the ovarian reserve, morphometric analysis of ovarian follicles showed maintenance of primordial follicles in Grem2-/- mice like wild type littermates. While Grem2 mRNA transcripts were not detected in the pituitary, Grem2 is expressed in hypothalami of wild type female mice, suggesting the potential for dysfunction in multiple tissues composing the hypothalamic-pituitary-ovarian axis that contribute to the subfertility phenotype. Additionally, screening 106 women with primary ovarian insufficiency identified one individual with a heterozygous variant in GREM2 that lies within the predicted BMP-GREM2 interface. In total, these data suggest Grem2 is necessary for female fecundity by playing a novel role in regulating the HPO axis and contributing to female reproductive disease.

Improved preservation of ovarian tissue morphology that is compatible with antigen detection using a fixative mixture of formalin and acetic acid

STUDY QUESTION

Can ovarian tissue morphology be better preserved whilst enabling histological molecular analyses following fixation with a novel fixative, neutral buffered formalin (NBF) with 5% acetic acid (referred to hereafter as Form-Acetic)?

SUMMARY ANSWER

Fixation with Form-Acetic improved ovarian tissue histology compared to NBF in multiple species while still enabling histological molecular analyses.

WHAT IS KNOWN ALREADY

NBF fixation results in tissue shrinkage in various tissue types including the ovary. Components of ovarian tissue, notably follicles, are particularly susceptible to NBF-induced morphological alterations and can lead to data misrepresentation. Bouin’s solution (which contains 5% acetic acid) better preserves tissue architecture compared to NBF but is limited for immunohistochemical analyses.

STUDY DESIGN, SIZE, DURATION

A comparison of routinely used fixatives, NBF and Bouin’s, and a new fixative, Form-Acetic was carried out. Ovarian tissue was used from three different species: human (n = 5 patients), sheep (n = 3; 6 ovaries; 3 animals per condition) and mouse (n = 14 mice; 3 ovaries from 3 different animals per condition).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Ovarian tissue from humans (aged 13 weeks to 32 years), sheep (reproductively young i.e. 3–6 months) and mice (10 weeks old) were obtained and fixed in 2 ml NBF, Bouin’s or Form-Acetic for 4, 8, and 24 h at room temperature. Tissues were embedded and sectioned. Five-micron sections were stained with haemotoxylin and eosin (H&E) and the percentage of artefact (clear space as a result of shrinkage) between ovarian structures was calculated. Additional histological staining using Periodic acid-Schiff and Masson’s trichrome were performed on 8 and 24 h NBF, Bouin’s and Form-Acetic fixed samples to assess the compatibility of the new fixative with stains. On ovarian tissue fixed for both 8 and 24 h in NBF and Form-Acetic, immunohistochemistry (IHC) studies to detect FOXO3a, FoxL2, collagen IV, laminin and anti-Müllerian hormone (AMH) proteins were performed in addition to the terminal deoxynucleotidyl transferase nick end labelling (TUNEL) assay to determine the compatibility of Form-Acetic fixation with types of histological molecular analyses.

MAIN RESULTS AND THE ROLE OF CHANCE

Fixation in Form-Acetic improved ovarian tissue morphology compared to NBF from all three species and either slightly improved or was comparable to Bouin’s for human, mouse and sheep tissues. Form-Acetic was compatible with H&E, Periodic acid-Schiff and Masson’s trichrome staining and all proteins (FOXO3a, FoxL2, collagen IV and laminin and AMH) could be detected via IHC. Furthermore, Form-Acetic, unlike NBF, enabled antigen recognition for most of the proteins tested without the need for antigen retrieval. Form-Acetic also enabled the detection of damaged DNA via the TUNEL assay using fluorescence.

LARGE SCALE DATA

N/A

LIMITATIONS, REASONS FOR CAUTION

In this study, IHC analysis was performed on a select number of protein types in ovarian tissue thus encouraging further studies to confirm the use of Form-Acetic in enabling the detection of a wider range of protein forms in addition to other tissue types.

WIDER IMPLICATIONS OF THE FINDINGS

The simplicity in preparation of Form-Acetic and its superior preservative properties whilst enabling forms of histological molecular analyses make it a highly valuable tool for studying ovarian tissue. We, therefore, recommend that Form-Acetic replaces currently used fixatives and encourage others to introduce it into their research workflow.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the Oxford Medical Research Council Doctoral Training Programme (Oxford MRC-DTP) grant awarded to B.D.B. (Grant no. MR/N013468/1), the Fondation Hoffmann supporting R.A. and the Petroleum Technology Development Fund (PTDF) awarded to B.V.A.

Spermidine at supraphysiological doses induces oxidative stress and granulosa cell apoptosis in mouse ovaries

Given that spermidine is associated with aging-related diseases and it is a potential target for delaying aging, functional studies on supraphysiological levels of spermidine are required. Our previous studies showed that the granulosa layer arranged irregular and the follicular oocytes were shrunk in female mice injected intraperitoneally with spermidine at 150 mg/kg (Body weight) after 24 h. It indicated that supraphysiological levels of spermidine induced ovarian damage in female mice. The objective of this study was to investigate the effect of acute administration of supraphysiological spermidine on the ovary and granulosa cells in mice. The results showed that treatment with spermidine at 150 mg/kg (intraperitoneal) significantly increased the levels of both H₂O₂ and malondialdehyde and reduced total antioxidant capacity and the activities of catalase and superoxide dismutase in mouse ovaries. The contents of putrescine and spermine increased significantly in the ovaries of mice treated with spermidine. Treatment with spermidine at 150 mg/kg increased the apoptotic rate and reactive oxygen species levels of granulosa cells in mouse ovaries. Furthermore, the protein expression of P53, CASPASE 8 (Cleaved/Pro), CASPASE 9 (Cleaved/Pro) and CASPASE 3 (Cleaved/Pro) in granulosa cells of mice treated with spermidine were significantly upregulated, while BCL2 expression was significantly downregulated. In summary, our study demonstrates for the first time that spermidine at supraphysiological doses causes ovarian oxidative stress and induces granulosa cell apoptosis via the P53 and/or BCL2-CASPASEs pathway.

Optimized platelet rich plasma releasate (O-rPRP) repairs galactosemia-induced ovarian follicular loss in rats by activating mTOR signaling and inhibiting apoptosis

Platelet rich plasma contains a collection of growth factors, and an optimal formulation, named O-rPRP, contains the highest possible concentration of growth factors.

Purpose

Challenging the healing power of O-rPRP in a high-galactose diet-induced premature ovarian insufficiency (POI) experimental rat model.

Methods

Rats were divided into four groups of ten rats each and treated for four week as follows; 1) the control group, fed with normal diet and received intraperitoneal (i.p.) injection of PBS once/week; 2) the POI group, fed with galactose diet (50%) and received PBS (i.p.) once/week; 3) the POI/O-rPRP group, fed a 50% galactose diet and received O-rPRP (i.p.) once/week; 4) the O-rPRP group (negative control), fed with a normal diet and received O-rPRP (i.p.) once/week. The levels of galactose, follicle stimulating hormone, 17 β-estradiol, anti-mullerian hormone and inhibin B were measured in serum samples. Western blotting and quantitative real-time PCR assays were employed to investigate the levels of miR-223, β1 integrin, p70S6k and MCL-1 in ovarian tissues.

Results

After O-rPRP treatment, β1 integrin expression was enhanced, and miR-223 expression was decreased. Unlike the untreated galactose group, in the group treated with O-rPRP, p70S6k and MCL-1 expression levels were increased, indicating that the mTOR growth signaling pathway was active and that apoptosis was inactive. After the introduction of O-rPRP, the number of follicles and the follicular maturation improved, which was consistent with the improvement of inhibin B levels and subsequent inhibition of FSH.

Conclusion

O-rPRP inhibited galactose-induced excessive atresia and provided an overall protective effect on the ovarian follicles.

Activin A forms a non-signaling complex with ACVR1 and type II Activin/BMP receptors via its finger 2 tip loop

Activin A functions in BMP signaling in two ways: it either engages ACVR1B to activate Smad2/3 signaling or binds ACVR1 to form a non-signaling complex (NSC). Although the former property has been studied extensively, the roles of the NSC remain unexplored. The genetic disorder fibrodysplasia ossificans progressiva (FOP) provides a unique window into ACVR1/Activin A signaling because in that disease Activin can either signal through FOP-mutant ACVR1 or form NSCs with wild-type ACVR1. To explore the role of the NSC, we generated 'agonist-only' Activin A muteins that activate ACVR1B but cannot form the NSC with ACVR1. Using one of these muteins, we demonstrate that failure to form the NSC in FOP results in more severe disease pathology. These results provide the first evidence for a biological role for the NSC in vivo and pave the way for further exploration of the NSC's physiological role in corresponding knock-in mice.

Demonstration of the utility of DOS-derived fragment libraries for rapid hit derivatisation in a multidirectional fashion

Organic synthesis underpins the evolution of weak fragment hits into potent lead compounds. Deficiencies within current screening collections often result in the requirement of significant synthetic investment to enable multidirectional fragment growth, limiting the efficiency of the hit evolution process. Diversity-oriented synthesis (DOS)-derived fragment libraries are constructed in an efficient and modular fashion and thus are well-suited to address this challenge. To demonstrate the effective nature of such libraries within fragment-based drug discovery, we herein describe the screening of a 40-member DOS library against three functionally distinct biological targets using X-Ray crystallography. Firstly, we demonstrate the importance for diversity in aiding hit identification with four fragment binders resulting from these efforts. Moreover, we also exemplify the ability to readily access a library of analogues from cheap commercially available materials, which ultimately enabled the exploration of a minimum of four synthetic vectors from each molecule. In total, 10-14 analogues of each hit were rapidly accessed in three to six synthetic steps. Thus, we showcase how DOS-derived fragment libraries enable efficient hit derivatisation and can be utilised to remove the synthetic limitations encountered in early stage fragment-based drug discovery.

miR-181a promotes porcine granulosa cell apoptosis by targeting TGFBR1 via the activin signaling pathway

Activin/Smad3 signaling plays a pivotal role in follicle development and atresia. However, the precise mechanisms underlying this process are not yet fully understood. Herein, we identified miR-181a as a central component of activin/Smad3-mediated follicle atresia. miR-181a was strikingly upregulated in porcine atretic follicles, which induced the apoptosis of porcine granulosa cells (GCs) in vitro. Furthermore, the transforming growth factor-β type 1 receptor (TGFBR1) was confirmed as a direct target of miR-181a by bioinformatics analysis and luciferase assays. Transfection with an miR-181a agomir repressed the TGFBR1 mRNA and protein levels. In addition, TGFBR1 overexpression repressed GC apoptosis, whereas TGFBR1 inhibition promoted GC apoptosis. miR-181a overexpression downregulated the phosphorylation of Smad3 and blocked the activation of TGF-β signaling. Moreover, activin A downregulated miR-181a expression and upregulated the TGFBR1 and p-Smad3 protein levels. Collectively, these data suggest that miR-181a regulates porcine GC apoptosis by targeting TGFBR1 via the activin signaling pathway.

ALK4-SMAD2/3-SMAD4 signaling mediates the activin A-induced suppression of PTX3 in human granulosa-lutein cells

As one of the members of the transforming growth factor-β (TGF-β) superfamily, activin A plays an important role in regulating follicular development and oocyte maturation. Pentraxin 3 (PTX3) is the key component that promotes the process of cumulus expansion during mammalian ovulation. At present, the regulation of PTX3 expression in human granulosa cells remains largely unknown. This study aimed to examine the effects of activin A on the expression of PTX3 in human granulosa-lutein (hGL) cells and to investigate the underlying molecular mechanisms. Using an established immortalized hGL cell line (SVOG) and primary hGL cells as study models, we demonstrated that activin A significantly increased the phosphorylation of SMAD2 and SMAD3, which suppressed the expression of PTX3 at both the mRNA and protein levels. Additionally, these effects induced by activin A were completely reversed by pretreatment with the TGF-β type I receptor inhibitor SB431542 and knockdown of ALK4. Furthermore, knockdown of SMAD2, SMAD3, or SMAD4 completely reversed the activin A-induced suppressive effects on PTX3 expression. Notably, the ChIP analyses demonstrated that phosphorylated SMADs could bind to human PTX3 promoter. Collectively, our results showed that the ALK4-SMAD2/3-SMAD4 signaling pathway most likely mediates the suppressive effect of activin A on PTX3 expression in hGL cells.

A counter gradient of Activin A and follistatin instructs the timing of hair cell differentiation in the murine cochlea

The mammalian auditory sensory epithelium has one of the most stereotyped cellular patterns known in vertebrates. Mechano-sensory hair cells are arranged in precise rows, with one row of inner and three rows of outer hair cells spanning the length of the spiral-shaped sensory epithelium. Aiding such precise cellular patterning, differentiation of the auditory sensory epithelium is precisely timed and follows a steep longitudinal gradient. The molecular signals that promote auditory sensory differentiation and instruct its graded pattern are largely unknown. Here, we identify Activin A and its antagonist follistatin as key regulators of hair cell differentiation and show, using mouse genetic approaches, that a local gradient of Activin A signaling within the auditory sensory epithelium times the longitudinal gradient of hair cell differentiation. Furthermore, we provide evidence that Activin-type signaling regulates a radial gradient of terminal mitosis within the auditory sensory epithelium, which constitutes a novel mechanism for limiting the number of inner hair cells being produced.

Uterine double-conditional inactivation of Smad2 and Smad3 in mice causes endometrial dysregulation, infertility, and uterine cancer

SMAD2 and SMAD3 are downstream proteins in the transforming growth factor-β (TGF β) signaling pathway that translocate signals from the cell membrane to the nucleus, bind DNA, and control the expression of target genes. While SMAD2/3 have important roles in the ovary, we do not fully understand the roles of SMAD2/3 in the uterus and their implications in the reproductive system. To avoid deleterious effects of global deletion, and given previous data showing redundant function of Smad2 and Smad3, a double-conditional knockout was generated using progesterone receptor-cre (Smad2/3 cKO) mice. Smad2/3 cKO mice were infertile due to endometrial hyperproliferation observed as early as 6 weeks of postnatal life. Endometrial hyperplasia worsened with age, and all Smad2/3 cKO mice ultimately developed bulky endometrioid-type uterine cancers with 100% mortality by 8 months of age. The phenotype was hormone-dependent and could be prevented with removal of the ovaries at 6 weeks of age but not at 12 weeks. Uterine tumor epithelium was associated with decreased expression of steroid biosynthesis genes, increased expression of inflammatory response genes, and abnormal expression of cell cycle checkpoint genes. Our results indicate the crucial role of SMAD2/3 in maintaining normal endometrial function and confirm the hormone-dependent nature of SMAD2/3 in the uterus. The hyperproliferation of the endometrium affected both implantation and maintenance of pregnancy. Our findings generate a mouse model to study the roles of SMAD2/3 in the uterus and serve to provide insight into the mechanism by which the endometrium can escape the plethora of growth regulatory proteins.

Gametogenesis: A journey from inception to conception

Gametogenesis, the process of forming mature germ cells, is an integral part of both an individual's and a species' health and well-being. This chapter focuses on critical male and female genetic and epigenetic processes underlying normal gamete formation through their differentiation to fertilization. Finally, we explore how knowledge gained from this field has contributed to progress in areas with great clinical promise, such as in vitro gametogenesis.

Activin A in Mammalian Physiology

Activins are dimeric glycoproteins belonging to the transforming growth factor beta superfamily and resulting from the assembly of two beta subunits, which may also be combined with alpha subunits to form inhibins. Activins were discovered in 1986 following the isolation of inhibins from porcine follicular fluid, and were characterized as ovarian hormones that stimulate follicle stimulating hormone (FSH) release by the pituitary gland. In particular, activin A was shown to be the isoform of greater physiological importance in humans. The current understanding of activin A surpasses the reproductive system and allows its classification as a hormone, a growth factor, and a cytokine. In more than 30 yr of intense research, activin A was localized in female and male reproductive organs but also in other organs and systems as diverse as the brain, liver, lung, bone, and gut. Moreover, its roles include embryonic differentiation, trophoblast invasion of the uterine wall in early pregnancy, and fetal/neonate brain protection in hypoxic conditions. It is now recognized that activin A overexpression may be either cytostatic or mitogenic, depending on the cell type, with important implications for tumor biology. Activin A also regulates bone formation and regeneration, enhances joint inflammation in rheumatoid arthritis, and triggers pathogenic mechanisms in the respiratory system. In this 30-yr review, we analyze the evidence for physiological roles of activin A and the potential use of activin agonists and antagonists as therapeutic agents.

The molecular complexity of primary ovarian insufficiency aetiology and the use of massively parallel sequencing

Primary ovarian insufficiency (POI) is a frequently occurring pathology, leading to infertility. Genetic anomalies have been described in POI and mutations in numerous genes have been definitively related to the pathogenesis of the disease. Some studies based on next generation sequencing (NGS) have been successfully undertaken as they have led to identify new mutations associated with POI aetiology. The purpose of this review is to present the most relevant molecules involved in diverse complex pathways, which may contribute towards POI. The main genes participating in bipotential gonad formation, sex determination, meiosis, folliculogenesis and ovulation are described to enable understanding how they may be considered putative candidates involved in POI. Considerations regarding NGS technical aspects such as design and data interpretation are mentioned. Successful NGS initiatives used for POI studying and future challenges are also discussed.

Acylated Ghrelin Supports the Ovarian Transcriptome and Follicles in the Mouse: Implications for Fertility

Ghrelin, an orexigenic gut-derived peptide, is gaining increasing attention due to its multifaceted role in a number of physiological functions, including reproduction. Ghrelin exists in circulation primarily as des-acylated and acylated ghrelin. Des-acyl ghrelin, until recently considered to be an inactive form of ghrelin, is now known to have independent physiological functionality. However, the relative contribution of acyl and des-acyl ghrelin to reproductive development and function is currently unknown. Here we used ghrelin-O-acyltransferase (GOAT) knockout (KO) mice that have no measurable levels of endogenous acyl ghrelin and chronically high levels of des-acyl ghrelin, to characterize how the developmental and life-long absence of acyl ghrelin affects ovarian development and reproductive capacity. We combined the assessment of markers of reproductive maturity and the capacity to breed with measures of ovarian morphometry, as well as with ovarian RNA sequencing analysis. Our data show that while GOAT KO mice retain the capacity to breed in young adulthood, there is a diminished number of ovarian follicles (per mm³) in the juvenile and adult ovaries, due to a significant reduction in the number of small follicles, particularly the primordial follicles. We also show pronounced specific changes in the ovarian transcriptome in the juvenile GOAT KO ovary, indicative of a potential for premature ovarian development. Collectively, these findings indicate that an absence of acyl ghrelin does not prevent reproductive success but that appropriate levels of acyl and des-acyl ghrelin may be necessary for optimal ovarian maturation.

TGFβ superfamily signaling and uterine decidualization

Decidualization is an intricate biological process where extensive morphological, functional, and genetic changes take place in endometrial stromal cells to support the development of an implanting blastocyst. Deficiencies in decidualization are associated with pregnancy complications and reproductive diseases. Decidualization is coordinately regulated by steroid hormones, growth factors, and molecular and epigenetic mechanisms. Transforming growth factor β (TGFβ) superfamily signaling regulates multifaceted reproductive processes. However, the role of TGFβ signaling in uterine decidualization is poorly understood. Recent studies using the Cre-LoxP strategy have shed new light on the critical role of TGFβ signaling machinery in uterine decidualization. Herein, we focus on reviewing exciting findings from studies using both mouse genetics and in vitro cultured human endometrial stromal cells. We also delve into emerging mechanisms that underlie decidualization, such as non-coding RNAs and epigenetic modifications. We envision that future studies aimed at defining the interrelationship among TGFβ signaling circuitries and their potential interactions with epigenetic modifications/non-coding RNAs during uterine decidualization will open new avenues to treat pregnancy complications associated with decidualization deficiencies.

The TGF-β Family in the Reproductive Tract

The transforming growth factor β (TGF-β) family has a profound impact on the reproductive function of various organisms. In this review, we discuss how highly conserved members of the TGF-β family influence the reproductive function across several species. We briefly discuss how TGF-β-related proteins balance germ-cell proliferation and differentiation as well as dauer entry and exit in Caenorhabditis elegans. In Drosophila melanogaster, TGF-β-related proteins maintain germ stem-cell identity and eggshell patterning. We then provide an in-depth analysis of landmark studies performed using transgenic mouse models and discuss how these data have uncovered basic developmental aspects of male and female reproductive development. In particular, we discuss the roles of the various TGF-β family ligands and receptors in primordial germ-cell development, sexual differentiation, and gonadal cell development. We also discuss how mutant mouse studies showed the contribution of TGF-β family signaling to embryonic and postnatal testis and ovarian development. We conclude the review by describing data obtained from human studies, which highlight the importance of the TGF-β family in normal female reproductive function during pregnancy and in various gynecologic pathologies.

The role of Notch signaling in the mammalian ovary

The Notch pathway is a contact-dependent, or juxtacrine, signaling system that is conserved in metazoan organisms and is important in many developmental processes. Recent investigations have demonstrated that the Notch pathway is active in both the embryonic and postnatal ovary and plays important roles in events including follicle assembly and growth, meiotic maturation, ovarian vasculogenesis and steroid hormone production. In mice, disruption of the Notch pathway results in ovarian pathologies affecting meiotic spindle assembly, follicle histogenesis, granulosa cell proliferation and survival, corpora luteal function and ovarian neovascularization. These aberrations result in abnormal folliculogenesis and reduced fertility. The knowledge of the cellular interactions facilitated by the Notch pathway is an important area for continuing research, and future studies are expected to enhance our understanding of ovarian function and provide critical insights for improving reproductive health. This review focuses on the expression of Notch pathway components in the ovary, and on the multiple functions of Notch signaling in follicle assembly, maturation and development. We focus on the mouse, where genetic investigations are possible, and relate this information to the human ovary.

GLI1+ progenitor cells in the adrenal capsule of the adult mouse give rise to heterotopic gonadal-like tissue

As certain strains of mice age, hyperplastic lesions resembling gonadal tissue accumulate beneath the adrenal capsule. Gonadectomy (GDX) accelerates this heterotopic differentiation, resulting in the formation of wedge-shaped adrenocortical neoplasms that produce sex steroids. Stem/progenitor cells that reside in the adrenal capsule and retain properties of the adrenogonadal primordium are thought to be the source of this heterotopic tissue. Here, we demonstrate that GLI1⁺ progenitors in the adrenal capsule give rise to gonadal-like cells that accumulate in the subcapsular region. A tamoxifen-inducible Cre driver (Gli1-creER^T2) and two reporters (R26R-lacZ, R26R-confetti) were used to track the fate of GLI1⁺ cells in the adrenal glands of B6D2F2 mice, a strain that develops both GDX-induced adrenocortical neoplasms and age-dependent subcapsular cell hyperplasia. In gonadectomized B6D2F2 mice GLI1⁺ progenitors contributed to long-lived adrenal capsule cells and to adrenocortical neoplasms that expressed Gata4 and Foxl2, two prototypical gonadal markers. Pdgfra, a gene expressed in adrenocortical stromal cells, was upregulated in the GDX-induced neoplasms. In aged non-gonadectomized B6D2F2 mice GLI1⁺ progenitors gave rise to patches of subcapsular cell hyperplasia. Treatment with GANT61, a small-molecule GLI antagonist, attenuated the upregulation of gonadal-like markers (Gata4, Amhr2, Foxl2) in response to GDX. These findings support the premise that GLI1⁺ progenitor cells in the adrenal capsule of the adult mouse give rise to heterotopic tissue.

Activin A upregulates PTGS2 expression and increases PGE2 production in human granulosa-lutein cells

Activin A is one of the members of transforming growth factor-β superfamily that is expressed in human large luteal cells, and may act in an autocrine/paracrine manner to regulate luteal function. Prostaglandin-endoperoxide synthase 2 (PTGS2) enzyme and its derivative, prostaglandin E2 (PGE2), play significant roles in the regulation of corpus luteum formation and maintenance. To date, whether activin A can induce the expression of PTGS2 and the production of PGE2 in human granulosa-lutein cells is largely unknown. The aim of this study was to examine the effects of activin A on the regulation of PTGS2 expression and PGE2 production in human granulosa-lutein cells, and to investigate the underlying signal transduction mechanisms. In this study, the immortalized (SVOG cells) and primary human granulosa-lutein cells were used as the cell models. A TGF-β/activin type I receptor inhibitor, SB431542 and small interfering RNAs were used to investigate the activin A-induced downstream signaling pathway. We have demonstrated that activin A upregulated the expression of PTGS2 and increased the production of PGE2 via an ACVR1B-mediated SMAD2/3–SMAD4 signaling pathway. Our results suggest that activin A may be involved in the modulation of human corpus luteum formation via the induction of PTGS2 expression and PGE2 production.

Structure and activation of pro-activin A

Activins are growth factors with multiple roles in the development and homeostasis. Like all TGF-β family of growth factors, activins are synthesized as large precursors from which mature dimeric growth factors are released proteolytically. Here we have studied the activation of activin A and determined crystal structures of the unprocessed precursor and of the cleaved pro-mature complex. Replacing the natural furin cleavage site with a HRV 3C protease site, we show how the protein gains its bioactivity after proteolysis and is as active as the isolated mature domain. The complex remains associated in conditions used for biochemical analysis with a dissociation constant of 5 nM, but the pro-domain can be actively displaced from the complex by follistatin. Our high-resolution structures of pro-activin A share features seen in the pro-TGF-β1 and pro-BMP-9 structures, but reveal a new oligomeric arrangement, with a domain-swapped, cross-armed conformation for the protomers in the dimeric protein.

Activins are members of the TGF-β family of growth factors that are processed from precursors into the mature proteins. Here, the authors use structural biology and biochemistry to examine the protein domain organisation and gain insights into the activation of pro-activin A.

Activins and Inhibins: Roles in Development, Physiology, and Disease

Since their original discovery as regulators of follicle-stimulating hormone (FSH) secretion and erythropoiesis, the TGF-β family members activin and inhibin have been shown to participate in a variety of biological processes, from the earliest stages of embryonic development to highly specialized functions in terminally differentiated cells and tissues. Herein, we present the history, structures, signaling mechanisms, regulation, and biological processes in which activins and inhibins participate, including several recently discovered biological activities and functional antagonists. The potential therapeutic relevance of these advances is also discussed.

Deletion of Arid1a in Reproductive Tract Mesenchymal Cells Reduces Fertility in Female Mice

Women with endometriosis can suffer from decreased fecundity or complete infertility via abnormal oocyte function or impaired placental-uterine interactions required for normal pregnancy establishment and maintenance. Although AT-rich interactive domain 1A (SWI-like) (ARID1A) is a putative tumor suppressor in human endometrial cancers and endometriosis-associated ovarian cancers, little is known about its role in normal uterine function. To study the potential function of ARID1A in the female reproductive tract, we generated mice with a conditional knockout of Arid1a using anti-Müllerian hormone receptor 2-Cre. Female Arid1a conditional knockout mice exhibited a progressive decrease in number of pups per litter, with a precipitous decline after the second litter. We observed no tumors in virgin mice, although one knockout mouse developed a uterine tumor after pregnancy. Unstimulated virgin female knockout mice showed normal oviductal, ovarian, and uterine histology. Uteri of Arid1a knockout mice showed a normal decidualization response and appropriate responses to estradiol and progesterone stimulation. In vitro studies using primary cultures of human endometrial stromal fibroblasts revealed that small interfering RNA knockdown of ARID1A did not affect decidualization in vitro. Timed pregnancy studies revealed the significant resorption of embryos at Embryonic Day 16.5 in knockout mice in the third pregnancy. In addition to evidence of implantation site hemorrhage, pregnant Arid1a knockout mice showed abnormal placental morphology. These results suggest that Arid1a supports successful pregnancy through its role in placental function.

Biological activity and in vivo half-life of pro-activin A in male rats

Mature TGF-β proteins are used in vivo to promote bone growth, combat obesity, reverse fibrosis and pulmonary arterial hypertension, and as potential rejuvenation factors. However, the serum half-life of this family of growth factors is short (∼5 min), limiting their therapeutic potential. Because TGF-β proteins are normally secreted from cells with their prodomains attached, we considered whether these molecules could extend the in vivo half-life and activity of their respective growth factors. Using activin A as a model ligand, we initially modified the cleavage site between the pro- and mature domains to ensure complete processing of the activin A precursor. Co-immunoprecipitation studies confirmed mature activin A is secreted from cells in a non-covalent complex with its prodomain, however, the affinity of this interaction is not sufficient to suppress activin A in vitro biological activity. The plasma clearance profiles of purified pro- and mature activin A were determined over a 4 h period in adult male rats. Both activin forms demonstrated a two-phase decay, with the half-life of pro-activin A (t1/2 fast = 12.5 min, slow = 31.0 min) being greater than that of mature activin A (t1/2 fast = 5.5 min, slow = 20.3 min). Both pro- and mature activin A induced significant increases in serum follicle stimulating hormone levels after 4 h, but no differences were observed in the relative in vivo bioactivities of the two activin isoforms. Increased serum half-life of activin A in the presence of its prodomain identifies a new means to increase the therapeutic effectiveness of TGF-β proteins.

Inhibitors of c-Jun phosphorylation impede ovine primordial follicle activation

STUDY HYPOTHESIS

Is the c-Jun-N-terminal kinase (JNK) pathway implicated in primordial follicle activation?

STUDY FINDING

Culture of ovine ovarian cortex in the presence of two different c-Jun phosphorylation inhibitors impeded pre-antral follicle activation.

WHAT IS KNOWN ALREADY

Despite its importance for fertility preservation therapies, the mechanisms of primordial follicle activation are poorly understood. Amongst different signalling pathways potentially involved, the JNK pathway has been previously shown to be essential for cell cycle progression and pre-antral follicle development in mice.

STUDY DESIGN, SAMPLES/MATERIALS, METHODS

Ovine ovarian cortex pieces were cultured with varying concentrations of SP600125, JNK inhibitor VIII or anti-Mullerian hormone (AMH) in the presence of FSH for 9 days. Follicular morphometry and immunohistochemistry for proliferating cell nuclear antigen (PCNA), apoptosis and follicle activation (Foxo3a) were assessed.

MAIN RESULTS AND THE ROLE OF CHANCE

Inhibition of primordial follicle activation occurred in the presence of SP600125, JNK inhibitor VIII and AMH when compared with controls (all P < 0.05) after 2 days of culture. However, only in the highest concentrations used was the inhibition of activation associated with induction of follicular apoptosis (P < 0.05). In growing follicles, PCNA antigen expression was reduced when the JNK inhibitors or AMH were used (P < 0.05 versus control), indicating reduced proliferation of the somatic compartment.

LIMITATIONS, REASONS FOR CAUTION

Although we evaluated the effects of inhibition of c-Jun phosphorylation on primordial follicle development, we did not determine the cellular targets and mechanism of action of the inhibitors.

WIDER IMPLICATIONS OF THE FINDINGS

These results are the first to implicate the JNK pathway in primordial follicle activation and could have significant consequences for the successful development of fertility preservation strategies and our understanding of primordial follicle activation.

LARGE SCALE DATA

n/a.

STUDY FUNDING AND COMPETING INTERESTS

Dr Michael J. Bertoldo and the laboratories involved in the present study were supported by a grant from 'Région Centre' (CRYOVAIRE, Grant number #320000268). There are no conflicts of interest to declare.

A Role of MicroRNAs in Cell Differentiation During Gonad Development

MicroRNAs (miRNAs) are a group of small noncoding RNA molecules that play a major role in posttranscriptional regulation of gene expression and are expressed in an organ-specific manner. One miRNA can potentially regulate the expression of several genes, depending on cell type and differentiation stage. miRNAs are differentially expressed in the male and female gonads and have an organ-specific reproductive function. Exerting their affect through germ cells and gonadal somatic cells, miRNAs regulate key proteins necessary for gonad development. The role of miRNAs in the testes is only starting to emerge though they have been shown to be required for adequate spermatogenesis. Widely explored in the ovary, miRNAs were suggested to play a fundamental role in follicles' assembly, growth, differentiation, and ovulation. In this chapter, we focus on data obtained from mice in which distinct proteins that participate in the biosynthesis of miRNAs were conditionally knocked out from germ cells (spermatogonial cells or oocytes) or gonadal somatic cells (Sertoli or granulosa cells). We detail recent advances in identification of particular miRNAs and their significance in the development and function of male and female gonads. miRNAs can serve as biomarkers and therapeutic agents of pathological conditions; thus, elucidating the branched and complex network of reproduction-related miRNAs will aid understanding of gonads' physiology and managing reproduction disorders.

Non-coding RNA in Ovarian Development and Disease

The ovary's primary function is to produce the mature female gamete, the oocyte that, following fertilization, can develop into an embryo, implant within the uterus and ultimately allow the mother's genetic material to be passed along to subsequent generations. In addition to supporting the generation of the oocyte, the ovary and specific ephemeral tissues within it, follicles and corpora lutea, produce steroids that regulate all aspects of the reproductive system, including the hypothalamic/pituitary axis, the reproductive tract (uterus, oviduct, cervix), secondary sex characteristics all of which are also essential for pregnancy and subsequent nurturing of the offspring. To accomplish these critical roles, ovarian development and function are tightly regulated by a number of exogenous (hypothalamic/pituitary) and endogenous (intraovarian) hormones. Within ovarian cells, intricate signalling cascades and transcriptional and post-transcriptional gene regulatory networks respond to these hormonal influences to provide the exquisite control over all of the temporal and spatial events that must be synchronized to allow this organ to successfully complete its function. This book chapter will focus specifically on the role of non-coding RNAs, their identification and described functional roles within the ovary with respect to normal function and their possible involvement in diseases, which involve the ovary.

RNAi-mediated knockdown of inhibin α subunit increased apoptosis in granulosa cells and decreased fertility in mice

Inhibin α (INHα), a member of TGFβ superfamily, is an important modulator of reproductive function that plays a vital role in follicular changes, cell differentiation, oocyte development, and ultimately in mammalian reproduction. However, the role of inhibin α in female fertility and ovarian function remains largely unknown. To define its role in reproduction, transgenic mice of RNAi-INHα that knock down the INHα expression by shRNAi were used. Inhibin α subunit gene was knocked down successfully at both transcriptional and translational levels by RNAi PiggyBac transposon (Pbi) mediated recombinant pshRNA vectors and purified DNA fragments were microinjected into mouse zygotes. Results showed that transgenic female mice were sub-fertile and exhibited 35.28% reduction in litter size in F1 generation relative to wild type. The decreased litter size associated with the reduction in the number of oocytes ovulated after puberty. Serum INHα level was significantly decreased in both 3 and 6 weeks; whereas, FSH was significantly increased in 3 weeks but not in 6 weeks. Furthermore, suppression of INHα expression significantly promoted apoptosis by up-regulating Caspase-3, bcl2, INHβB and GDF9 and down regulated Kitl and TGFβRIII genes both at transcriptional and translational levels. Moreover, it also dramatically reduced the progression of G1 phase of cell cycle and the number of cells in S phase as determined by flow cytometer. These results indicate that suppression of INHα expression in RNAi-transgenic mice leads to disruption of normal ovarian regulatory mechanism and causes reproductive deficiencies by promoting cellular apoptosis, arresting cellular progression and altering hormonal signaling.

Constitutive activation of transforming growth factor Beta receptor 1 in the mouse uterus impairs uterine morphology and function

Despite increasing evidence pointing to the essential involvement of the transforming growth factor beta (TGFB) superfamily in reproduction, a definitive role of TGFB signaling in the uterus remains to be unveiled. In this study, we generated a gain-of-function mouse model harboring a constitutively active (CA) TGFB receptor 1 (TGFBR1), the expression of which was conditionally induced by the progesterone receptor (Pgr)-Cre recombinase. Overactivation of TGFB signaling was verified by enhanced phosphorylation of SMAD2 and increased expression of TGFB target genes in the uterus. TGFBR1 Pgr-Cre CA mice were sterile. Histological, cellular, and molecular analyses demonstrated that constitutive activation of TGFBR1 in the mouse uterus promoted formation of hypermuscled uteri. Accompanying this phenotype was the upregulation of a battery of smooth muscle genes in the uterus. Furthermore, TGFB ligands activated SMAD2/3 and stimulated the expression of a smooth muscle maker gene, alpha smooth muscle actin (ACTA2), in human uterine smooth muscle cells. Immunofluorescence microscopy identified a marked reduction of uterine glands in TGFBR1 Pgr-Cre CA mice within the endometrial compartment that contained myofibroblast-like cells. Thus, constitutive activation of TGFBR1 in the mouse uterus caused defects in uterine morphology and function, as evidenced by abnormal myometrial structure, dramatically reduced uterine glands, and impaired uterine decidualization. These results underscore the importance of a precisely controlled TGFB signaling system in establishing a uterine microenvironment conducive to normal development and function.

Transcriptome profiling of granulosa and theca cells during dominant follicle development in the horse

Several aspects of equine ovarian physiology are unique among domestic species. Moreover, follicular growth patterns are very similar between horses and humans. This study aimed to characterize, for the first time, global gene expression profiles associated with growth and preovulatory (PO) maturation of equine dominant follicles. Granulosa cells (GCs) and theca interna cells (TCs) were harvested from follicles (n = 5) at different stages of an ovulatory wave in mares corresponding to early dominance (ED; diameter ≥22 mm), late dominance (LD; ≥33 mm) and PO stage (34 h after administration of crude equine gonadotropins at LD stage), and separately analyzed on a horse gene expression microarray, followed by validation using quantitative PCR and immunoblotting/immunohistochemistry. Numbers of differentially expressed transcripts (DETs; ≥2-fold; P < 0.05) during the ED-LD and LD-PO transitions were 546 and 2419 in GCs and 5 and 582 in TCs. The most prominent change in GCs was the down-regulation of transcripts associated with cell division during both ED-LD and LD-PO. In addition, DET sets during LD-PO in GCs were enriched for genes involved in cell communication/adhesion, antioxidation/detoxification, immunity/inflammation, and cholesterol biosynthesis. In contrast, the largest change in TCs during the LD-PO transition was an up-regulation of genes involved in immune activation, with other DET sets mapping to GPCR/cAMP signaling, lipid/amino acid metabolism, and cell proliferation/survival and differentiation. In conclusion, distinct expression profiles were identified between growing and PO follicles and, particularly, between GCs and TCs within each stage. Several DETs were identified that have not been associated with follicle development in other species.

Slow-freezing versus vitrification for human ovarian tissue cryopreservation

PURPOSE

Ovarian tissue can be cryopreserved prior to chemotherapy using either the slow-freezing or the vitrification method; however, the data on the equality of the procedures are still conflicting. In this study, a comparison of the cryo-damage of human ovarian tissue induced by either vitrification or slow-freezing was performed.

METHODS

Ovarian tissue from 23 pre-menopausal patients was cryopreserved with either slow-freezing or vitrification. After thawing/warming, the tissue was histologically and immunohistochemically analyzed and cultured in vitro. During tissue culture the estradiol release was assessed.

RESULTS

No significant difference was found in the proportion of high-quality follicles after thawing/warming in the slow-freezing and vitrification group, respectively (72.7 versus 66.7 %, p = 0.733). Estradiol secretion by the ovarian tissue was similar between groups during 18 days in vitro culture (area-under-the-curve 5,411 versus 13,102, p = 0.11). Addition of Sphingosine-1-Phosphate or Activin A to the culture medium did not alter estradiol release in both groups. The proportion of Activated Caspase-3 or 'Proliferating-Cell-Nuclear-Antigen' positive follicles at the end of the culture period was similar between slow-freezing and vitrification.

CONCLUSION(S)

Slow-freezing and vitrification result in similar morphological integrity after cryopreservation, a similar estradiol release in culture, and similar rates of follicular proliferation and apoptosis after culture.

Finding novel molecular connections between developmental processes and disease

Identifying molecular connections between developmental processes and disease can lead to new hypotheses about health risks at all stages of life. Here we introduce a new approach to identifying significant connections between gene sets and disease genes, and apply it to several gene sets related to human development. To overcome the limits of incomplete and imperfect information linking genes to disease, we pool genes within disease subtrees in the MeSH taxonomy, and we demonstrate that such pooling improves the power and accuracy of our approach. Significance is assessed through permutation. We created a web-based visualization tool to facilitate multi-scale exploration of this large collection of significant connections (http://gda.cs.tufts.edu/development). High-level analysis of the results reveals expected connections between tissue-specific developmental processes and diseases linked to those tissues, and widespread connections to developmental disorders and cancers. Yet interesting new hypotheses may be derived from examining the unexpected connections. We highlight and discuss the implications of three such connections, linking dementia with bone development, polycystic ovary syndrome with cardiovascular development, and retinopathy of prematurity with lung development. Our results provide additional evidence that plays a key role in the early pathogenesis of polycystic ovary syndrome. Our evidence also suggests that the VEGF pathway and downstream NFKB signaling may explain the complex relationship between bronchopulmonary dysplasia and retinopathy of prematurity, and may form a bridge between two currently-competing hypotheses about the molecular origins of bronchopulmonary dysplasia. Further data exploration and similar queries about other gene sets may generate a variety of new information about the molecular relationships between additional diseases.

Understanding the roles that genes involved in normal human development can play in disease processes is an important part of predicting disease risk and designing novel treatment approaches. In this study, we have identified classes of disease that are associated with a surprisingly large number of genes involved in any of several tissue-specific developmental processes. To do so, we developed a novel approach whose strength comes from pooling genetic information across related diseases, overcoming problems ordinarily posed by limited information about individual gene-disease relationships. We demonstrate the method's efficacy both by examining its ability to highlight connections between gene sets and disease classes that are known to be related, and by demonstrating that the approach recovers expected broad classes of connections, such as those between heart development and cardiovascular disorders. However, by examining unexpected connections in this data set, we are able to develop new understanding of some surprising disease relationships, such as the one between dementia and osteoporosis. Such connections may lead to a better overall understanding of the role of development in lifelong health, as well as to the design of new methods to treat a range of diseases.

Activin-A promotes the development of goat isolated secondary follicles in vitro

The role of activin-A in follicular development and on the mRNA expression levels of different genes in goat secondary follicles was evaluated. Goat secondary follicles (≥ 150 μm) were cultured for 18 days under control conditions or with the addition of either 50 or 100 ng/ml activin-A (Experiment 1). The mRNA levels for the genes that code for activin-A, ActR-IA, ActR-IB, ActR-IIA, ActR-IIB, follicle stimulating hormone receptor (FSH-R) and P450 aromatase were measured in each condition (Experiment 2). We observed that after 6 days of culture, the antrum formation rate was higher in cultures with added activin-A than in the cultured control (P < 0.05). The addition of 50 ng/ml activin-A increased the follicular growth rate in the final third of the culture (days 12-18), resulting in a higher percentage of meiosis resumption (P < 0.05). On day 6, the addition of activin-A (50 ng/ml) increased the levels of ActR-IA mRNA compared with the cultured control (P < 0.05). After 18 days, the addition of 50 ng/ml activin-A significantly increased the levels of its own mRNA compared with the non-cultured control. Moreover, this treatment reduced the mRNA levels of P450 aromatase in comparison with the cultured control (P < 0.05). Higher levels of P450 aromatase mRNA were found for both activin-A treatments compared with the non-cultured control (P < 0.05). No difference in estradiol levels was detected among any of the tested treatments. In conclusion, the addition of activin-A to culture medium stimulated early antrum formation as well as an increase in the daily follicular growth rate and the percentage of meiosis resumption.

SMAD7 antagonizes key TGFβ superfamily signaling in mouse granulosa cells in vitro

Transforming growth factor β (TGFβ) superfamily signaling is essential for female reproduction. Dysregulation of the TGFβ signaling pathway can cause reproductive diseases. SMA and MAD (mothers against decapentaplegic) (SMAD) proteins are downstream signaling transducers of the TGFβ superfamily. SMAD7 is an inhibitory SMAD that regulates TGFβ signalingin vitro. However, the function of SMAD7 in the ovary remains poorly defined. To determine the signaling preference and potential role of SMAD7 in the ovary, we herein examined the expression, regulation, and function of SMAD7 in mouse granulosa cells. We showed that SMAD7 was expressed in granulosa cells and subject to regulation by intraovarian growth factors from the TGFβ superfamily. TGFB1 (TGFβ1), bone morphogenetic protein 4, and oocyte-derived growth differentiation factor 9 (GDF9) were capable of inducingSmad7expression, suggesting a modulatory role of SMAD7 in a negative feedback loop. Using a small interfering RNA approach, we further demonstrated that SMAD7 was a negative regulator of TGFB1. Moreover, we revealed a link between SMAD7 and GDF9-mediated oocyte paracrine signaling, an essential component of oocyte–granulosa cell communication and folliculogenesis. Collectively, our results suggest that SMAD7 may function during follicular development via preferentially antagonizing and/or fine-tuning essential TGFβ superfamily signaling, which is involved in the regulation of oocyte–somatic cell interaction and granulosa cell function.