Targeted deletion of NR2F2 and VCAM1 in theca cells impacts ovarian follicular development: insights into polycystic ovary syndrome?†

Defining features of polycystic ovary syndrome (PCOS) include elevated expression of steroidogenic genes, theca cell androgen biosynthesis, and peripheral levels of androgens. In previous studies, we identified vascular cell adhesion molecule 1 (VCAM1) as a selective androgen target gene in specific NR2F2/SF1 (+/+) theca cells. By deleting NR2F2 and VCAM1 selectively in CYP17A1 theca cells in mice, we documented that NR2F2 and VCAM1 impact distinct and sometimes opposing theca cell functions that alter ovarian follicular development in vivo: including major changes in ovarian morphology, steroidogenesis, gene expression profiles, immunolocalization images (NR5A1, CYP11A1, NOTCH1, CYP17A1, INSL3, VCAM1, NR2F2) as well as granulosa cell functions. We propose that theca cells impact follicle integrity by regulating androgen production and action, as well as granulosa cell differentiation/luteinization in response to androgens and gonadotropins that may underlie PCOS.

Evaluation of Lipids and Lipid-Related Transcripts in Human and Ovine Theca Cells and an in Vitro Mouse Model Exposed to the Obesogen Chemical Tributyltin

BACKGROUND

Exposure to obesogenic chemicals has been reported to result in enhanced adipogenesis, higher adipose tissue accumulation, and reduced ovarian hormonal synthesis and follicular function. We have reported that organotins [tributyltin (TBT) and triphenyltin (TPT)] dysregulate cholesterol trafficking in ovarian theca cells, but, whether organotins also exert lipogenic effects on ovarian cells remains unexplored.

OBJECTIVE

We investigated if environmentally relevant exposures to organotins [TBT, TPT, or dibutyltin (DBT)] induce lipid dysregulation in ovarian theca cells and the role of the liver X receptor (LXR) in this effect. We also tested the effect of TBT on oocyte maturation and neutral lipid accumulation, and lipid-related transcript expression in cumulus cells and preimplantation embryos.

METHODS

Primary theca cell cultures derived from human and ovine ovaries were exposed to TBT, TPT, or DBT (1, 10, or 50   ng / ml ). The effect of these chemical exposures on neutral lipid accumulation, lipid abundance and composition, lipid homeostasis-related gene expression, and cytokine secretion was evaluated using liquid chromatography-mass spectrometry (LC-MS), inhibitor-based methods, cytokine secretion, and lipid ontology analyses. We also exposed murine cumulus-oocyte complexes to TBT and evaluated oocyte maturation, embryo development, and lipid homeostasis-related mRNA expression in cumulus cells and blastocysts.

RESULTS

Exposure to TBT resulted in higher intracellular neutral lipids in human and ovine primary theca cells. In ovine theca cells, this effect was dose-dependent, independent of cell stage, and partially mediated by LXR. DBT and TPT resulted in higher intracellular neutral lipids but to a lesser extent in comparison with TBT. More than 140 lipids and 9 cytokines were dysregulated in TBT-exposed human theca cells. Expression of genes involved in lipogenesis and fatty acid synthesis were higher in theca cells, as well as in cumulus cells and blastocysts exposed to TBT. However, TBT did not impact the rates of oocyte maturation or blastocyst development.

DISCUSSION

TBT induced dyslipidemia in primary human and ovine theca cells, which may be responsible for some of the TBT-induced fertility dysregulations reported in rodent models of TBT exposure. https://doi.org/10.1289/EHP13955.

Effects of exogenous energy on synthesis of steroid hormones and expression characteristics of the CREB/StAR signaling pathway in theca cells of laying hen

Energy and the cAMP-response element binding protein (CREB)/steroidogenic acute regulatory protein (StAR) signaling pathway play important roles in steroid hormone production and follicular development in hens. This present study aimed to investigate the effects of exogenous energy on the synthesis of steroid hormones and the expression characteristics of the CREB/StAR signaling pathway in theca cells of laying hen. The primary theca cells of small yellow follicles were randomly divided into 6 treatments and cultured in medium with glucose concentrations of 1, 1.5, 3, 4.5, 6, and 7.5 mg/mL for 48 h. It was found that growth was robust and cell outlines were clear when cells were cultured with 1, 1.5, 3, and 4.5 mg/mL glucose, but cell viability was diminished and cell density decreased after exposure to glucose at 6 and 7.5 mg/mL for 48 h. Cell viability showed an increasing and then decreasing quadratic response to increasing glucose concentration in culture (r2 = 0.688, P < 0.001). The cell viability of theca cells cultured with 4.5 mg/mL glucose was greater than those cultured with 1, 1.5, 6, and 7.5 mg/mL glucose (P < 0.05). The concentration of estradiol in the medium containing 3 mg/mL glucose was higher than in medium containing 1, 1.5, and 6 mg/mL glucose (P < 0.05). There was an increasing and then decreasing quadratic correlation between progesterone concentrations and glucose concentrations (r2 = 0.522, P = 0.002). The concentration of progesterone in medium with 4.5 mg/mL glucose was higher than in medium with 1 and 7.5 mg/mL glucose (P < 0.05). There was an increasing and then decreasing quadratic correlation between the relative expression of CREB1 (r2 = 0.752, P < 0.001), StAR (r2 = 0.456, P = 0.002), CYP1B1 (r2 = 0.568, P < 0.001), and 3β-HSD (r2 = 0.319, P = 0.018) in theca cells of laying hens and glucose concentrations after treatment with different glucose concentrations for 48 h. After treatment with 4.5 mg/mL glucose, the expression of StAR, CYP1B1, and 3β-HSD genes were increased compared to treatment with 1, 1.5, 3, 6, and 7.5 mg/mL glucose (P < 0.001). There was an increasing and then decreasing quadratic correlation between glucose concentrations and protein expression of CREB1 (r2 = 0.819, P < 0.001), StAR (r2 = 0.844, P < 0.001), 3β-HSD (r2 = 0.801, P < 0.001), and CYP11A1 (r2 = 0.800, P < 0.001) in theca cells of laying hens. The protein expression of CREB1, StAR, and 3β-HSD in theca cells cultured with 4.5 mg/mL glucose was higher than in other groups (P < 0.001). The results indicate that the appropriate glucose concentration (4.5 mg/mL) can improve the synthesis of steroid hormones in theca cells of laying hens through the upregulation of key genes and proteins in the CREB/StAR signaling pathway.

Comparing ovarian expression of sperm acrosome associated 3 protein in young and adult queens

The purpose of this research was to quantify sperm acrosome associated 3 protein expression in the ovaries of young (3.0 ± 0.9 months, n = 11) and adult (10.4 ± 2.8 months, n = 11) queens. Immunohistochemistry was performed on formalin-fixed, paraffin-embedded feline ovarian sections. Ovaries were obtained following routine ovariohysterectomy of queens. Cellular expression of sperm acrosome associated 3 protein was measured in primordial, primary, secondary, and tertiary follicles using an image-analysis software's red, green, and blue stack and manual thresholding functions. The oocyte nucleus, ooplasm, granulosa cells, and theca cells were outlined using the freehand selection tool and mean grey value was recorded. Results from each cellular location were compared between age groups using a Student's t-test and between follicle stages using an analysis of variance. Compared to adult queens, younger queens had significantly greater sperm acrosome associated 3 protein expression in granulosa cells of primary, secondary, and tertiary follicles. Also, theca cells of secondary and tertiary follicles had significantly greater sperm acrosome associated 3 protein expression in younger queens compared to adult queens. The oocyte nucleus of primordial, primary, and secondary follicles had significantly greater sperm acrosome associated 3 protein expression in younger queens compared to adult queens. However, sperm acrosome associated 3 protein expression within the ooplasm did not differ significantly between age groups of any follicle type. More research is needed to determine what role sperm acrosome associated 3 protein may play in female fertility in animals as well as what mechanisms regulate ovarian sperm acrosome associated 3 protein expression over time.

Real-life exposure to Fusarium toxins deoxynivalenol and zearalenone triggers apoptosis and activates NLRP3 inflammasome in bovine primary theca cells

Cattle are deemed less susceptible to mycotoxins due to the limited internal exposure resulting from rumen microbiota activity. However, the significant amounts of Fusarium mycotoxins deoxynivalenol (DON) and zearalenone (ZEN) frequently detected in bovine follicular fluid samples suggest that they could affect ovarian function. Both mycotoxins trigger several patterns of cell death and activate the NLRP3 inflammasome in the intestine. In vitro studies have reported a number of adverse effects on bovine oocytes. However, the biological relevance of such findings with regard to realistic concentrations of DON and ZEN in bovine follicular fluid is still not clear. Hence, it is important to better characterize the effects of dietary exposure to DON and ZEN on the bovine ovary. Using bovine primary theca cells, this study investigated the effects of real-life patterns for bovine ovary exposure to DON and ZEN, but also DON metabolite DOM-1, on cell death and NLRP3 inflammasome activation. Exposure to DON starting from 0.1 μM significantly decreased theca cell viability. The kinetics of phosphatidylserine translocation and loss of membrane integrity showed that ZEN and DON, but not DOM-1, induce an apoptotic phenotype. qPCR analysis of the expression of NLRP3, PYCARD, IL-1β, IL-18, and GSDMD in primary theca cells at concentrations of mycotoxin previously reported in cow follicular fluid clearly indicated that DON and DOM-1 individually and in mixture, but not ZEN, activate NLRP3 inflammasome. Altogether, these results suggest that real-life dietary exposure of cattle to DON may induce inflammatory disorders in the ovary.

Expression of genes and enzymes involved in ovarian steroidogenesis in relation to human follicular development

Introduction

Granulosa cells (GCs) and theca cells (TCs) play a pivotal role in human ovarian steroidogenesis, facilitating the conversion of cholesterol into sex steroids that regulate normal reproductive function. This study aims to explore the expression patterns of key enzymes that govern human ovarian steroidogenesis throughout follicle development, employing both genomic and immunological methodologies.

Methods

Follicles and GCs obtained from women undergoing ovarian tissue cryopreservation (OTC) and in vitro fertilisation treatment were utilized. Gene expression data were obtained from a Chinese study using RNA sequencing and from microarray data generated in our laboratory to comprehensively analyse gene expression profiles across distinct stages of follicular development. To corroborate the localisation of key enzymes within GCs and TCs, immunohistochemistry analyses utilizing colourimetric and fluorescent techniques were conducted.

Results

Steroidogenesis-related enzymes displayed low gene expression levels during early follicle development. However, a notable upregulation of HSD3B2 was observed in GCs as follicles progressed to the antral/preovulatory stage, confirmed consistently using both microarray and RNA sequencing methodologies. Furthermore, immunohistochemical analyses effectively demonstrated that HSD3B2 were not only expressed in GCs, but co-localised with CYP17A1 within a specific subset of TCs surrounding human small antral follicles. Contributing to an enhanced progesterone production during the second half of the follicular phase was a significant upregulation of CYB5A in both microarray and RNA-seq datasets as follicles transition from the antral stage to the pre-ovulatory stage. Moreover, an augmented expression of DHCR24 and LDLR in both types of data, along with HMGCR expression expression in the microarray data, indicates increased substrate availability for ovarian steroidogenesis.

Discussion

This study confirms and extends that GCs gradually augment expression of HSD3B2 thereby enhancing their capacity for progesterone synthesis as follicles reach the size of selection at around 10 mm in diameter. This is supported by the expression CYB5A and possibly augmented availability of steroid precursors. A subset of TCs exhibit concurrent expression of CYP17A1 and HSD3B2, collectively contributing to the synthesis of 17-hydroxyprogesterone. These data significantly enhance our understanding of the dynamic regulation of progesterone throughout the process of follicular development.

Follicle development in pigs: State of the art

Understanding the factors and pathways involved with recruitment, atresia, and selection of follicles in the pig, may provide insight into approaches to limit fertility failures. Antral follicles depend upon FSH to the 2-3 mm stage, become codependent upon LH at 4-5 mm, and rely on LH when >5 mm. Within the follicle, gonadotropin binding, steroids, growth factors, and inhibin interact to determine the fate of the follicle. Continuous recruitment appears likely for follicles, and once >1 mm, they may have a limited period for survival, before selection or atresia. If true, then the number of healthy follicles that can respond to a hormone signal for selection, could vary by size and development stage. Which follicles are selected may depend upon their age, numbers of capillaries, granulosa and thecal cells, and FSH and LH receptors. This might also suggest that factors such as management, nutrition, and stress in prior weeks, could affect different cohorts of follicles to determine which of those from the ovarian population will be selected.

Developmental and hormonal regulation of FBN1 and OR4M1 mRNA in bovine granulosa cells

Recent studies have reported hormonal regulation of expression of fibrillin 1 (FBN1), the gene that encodes asprosin, in bovine theca cells, however, hormonal regulation of gene expression of FBN1 and the asprosin receptor, olfactory receptor 4M1 (OR4M1), has not been evaluated in granulosa cells (GC). This study was designed to characterize FBN1 and OR4M1 gene expression in GC during development of bovine dominant ovarian follicles, and to determine the hormonal regulation of FBN1 and OR4M1 mRNA expression in GC. GC FBN1 mRNA abundance was greater (P < 0.05) in medium (5.1-8 mm) estrogen inactive (EI) follicles than in large (>8.1 mm) or small (1-5 mm) EI follicles. In comparison, GC OR4M1 mRNA abundance was greater (P < 0.05) in small EI follicles than in large or medium EI follicles. Abundance of OR4M1 mRNA in GC of follicles collected on days 3 to 4 (early growth phase) and on days 5 to 6 (late growth phase) was similar, whereas FBN1 mRNA abundance was greater (P < 0.05) on days 5 to 6 vs days 3 to 4. Hormonal regulators for FBN1 mRNA abundance in cultured small-follicle GC were identified: TGFβ1 causing a 2.45-fold increase, WNT3A causing a 1.45-fold increase, and IGF1 causing a 65% decrease. Steroids, leptin, insulin, growth hormone, follicle stimulating hormone, fibroblast growth factor 9 and epidermal growth factor had no effect on FBN1 mRNA abundance. Abundance of OR4M1 mRNA in GC was regulated by progesterone with 3.55-fold increase, but other hormones did not affect GC OR4M1 mRNA abundance. Findings indicate that both FBN1 and OR4M1 gene expression are hormonally and developmentally regulated in bovine follicles, and thus may affect asprosin production and its subsequent role in ovarian follicular function in cattle.

AMH inhibits androgen production in human theca cells

Both excessive ovarian production of AMH and androgen are important features of polycystic ovary syndrome (PCOS). Present study aimed to explore the direct effect of AMH on androgen production in human theca cells. Primary cultured human theca cells were treated with AMH, an ALK2 (the BMP type 1 receptor) inhibitor and an ALK5 (the TGFβ type 1 receptor) inhibitor. AMH significantly suppresses the expression of the androgen synthesis-related enzyme CYP17A1 and reduces the production of androstenedione and testosterone in normal human theca cells and PCOS theca cells. Inhibitors of ALK2/3 and ALK5 antagonize the effect of AMH on the expression of CYP17A1. Although both ALK5 and ALK2 interact with AMHR2 in the presence of AMH, AMH activated neither TGFβR-Smads (Smad 2/3) nor BMPR-Smads (Smad 1/5/8). Our data suggested that AMH suppresses androgen synthesis-related enzyme CYP17A1 expression and inhibits androgen production in human theca cells, which process may be mediated by ALK2 and ALK5.

Human theca arises from ovarian stroma and is comprised of three discrete subtypes

Theca cells serve multiple essential functions during the growth and maturation of ovarian follicles, providing structural, metabolic, and steroidogenic support. While the function of theca during folliculogenesis is well established, their cellular origins and the differentiation hierarchy that generates distinct theca sub-types, remain unknown. Here, we performed single cell multi-omics analysis of primary cell populations purified from human antral stage follicles (1-3 mm) to define the differentiation trajectory of theca/stroma cells. We then corroborated the temporal emergence and growth kinetics of defined theca/stroma subpopulations using human ovarian tissue samples and xenografts of cryopreserved/thawed ovarian cortex, respectively. We identified three lineage specific derivatives termed structural, androgenic, and perifollicular theca cells, as well as their putative lineage-negative progenitor. These findings provide a framework for understanding the differentiation process that occurs in each primordial follicle and identifies specific cellular/molecular phenotypes that may be relevant to either diagnosis or treatment of ovarian pathologies.

Effects of grape phenolics, myricetin and piceatannol, on bovine granulosa and theca cell proliferation and steroid production in vitro

Myricetin (a flavonol) and piceatannol (a stilbenoid) are naturally occurring phenolic compounds in red wine with cardio-protective and anti-carcinogenic effects, but their potential reproductive effects have not been investigated. Thus, the present study was designed to determine if myricetin and piceatannol can directly affect ovarian function using bovine granulosa cells (GC) and theca cells (TC) as in vitro model systems to evaluate effects on cell proliferation and steroid production. In Experiment 1 and 2, myricetin and piceatannol at 30 μM blocked insulin-like growth factor 1 (IGF1)-induced progesterone production by GC without affecting GC numbers. In contrast, myricetin stimulated IGF1-induced estradiol production, whereas piceatannol at 30 μM inhibited IGF1-induced estradiol production by 90% in GC. In Experiment 3 and 4, TC androstenedione and progesterone production and TC proliferation was inhibited by myricetin and piceatannol at 30 μM. In Experiment 5, piceatannol (30 μM) reduced the Fusarium mycotoxin, beauvericin (6 μM)-induced inhibition on progesterone production and cell proliferation. Myricetin (30 μM) reduced the inhibitory effect of beauvericin on estradiol but not progesterone production or cell proliferation. In conclusion, the red wine phenols, myricetin and piceatannol, directly affected GC and TC steroidogenesis, and were able to reduce some of the inhibitory effects of beauvericin on GC function.

Changes in fibroblast growth factor receptors-1c, -2c, -3c, and -4 mRNA in granulosa and theca cells during ovarian follicular growth in dairy cattle

The various fibroblast growth factors (FGF) regulate their function via binding to 4 main FGF receptor (FGFR) subtypes and their splice variants, FGFR1b, FGF1c, FGFR2b, FGFR2c and FGFR3c and FGFR4, but which of these FGFR are expressed in the granulosa (GC) and theca cells (TC), the 2 main cell layers of ovarian follicles, or change during follicular development is unknown. We hypothesized that FGFR1c, FGFR2c and FGFR3c (but not FGFR4) gene expression in GC (but not TC) would change with follicular development. Hence, the objective of this study was to determine if abundance of FGFR1c, FGFR2c, FGFR3c, and FGFR4 mRNA change according to follicular size, steroidogenic status, and days post-ovulation during growth of first-wave dominant follicles in Holstein cattle exhibiting regular estrous cycles. Estrous cycles of non-lactating dairy cattle were synchronized, and ovaries were collected on either d 3 to 4 (n = 8) or d 5 to 6 (n = 8) post-ovulation for GC and TC RNA extraction from small (1-5 mm), medium (5.1 to 8 mm) or large (8.1-18 mm) follicles for real-time PCR analysis. In GC, FGFR1c and FGFR2c mRNA relative abundance was greater in estrogen (E2)-inactive (ie, concentrations of E2 < progesterone, P4) follicles of all sizes than in GC from large E2-active follicles (ie, E2 > P4), whereas FGFR3c and FGFR4 mRNA abundance did not significantly differ among follicle types or days post-estrus. In TC, medium E2-inactive follicles had greater FGFR1c and FGFR4 mRNA abundance than large E2-active and E2-inactive follicles on d 5 to 6 post-ovulation whereas FGFR2c and FGFR3c mRNA abundance did not significantly differ among follicle types or day post-estrus. In vitro experiments revealed that androstenedione increased abundance of FGFR1c, FGFR2c and FGFR4 mRNA in GC whereas estradiol decreased FGFR2c mRNA abundance. Neither androstenedione nor estradiol affected abundance of the various FGFR mRNAs in cultured TC. Taken together, the findings that FGFR1c and FGFR2c mRNA abundance was less in GC of E2-active follicles and FGFR1c and FGFR4 mRNA was greater in TC of medium inactive follicles at late than at early growing phase of the first dominant follicle support an anti-differentiation role for FGF and their FGFR as well as support the idea that steroid-induced changes in FGF and their receptors may regulate selection of dominant follicles in cattle.

Transcriptional regulation of CYP19A1 expression in chickens: ESR1, ESR2 and NR5A2 form a functional network

Aromatase, encoded by CYP19A1, is responsible for the conversion of androgen to estrogen, which plays a vital role in the development and function of the ovary and functions in many other physiological processes in both sexes. Instead of being expressed in ovarian granulosa cells, as in mammals, CYP19A1 is expressed in chickens in the theca cells of ovarian follicles, and the mechanism of CYP19A1 expression regulation remains unknown. Here, using immunofluorescence and western blotting assay, we first confirmed that CYP19A1 and FOXL2 (Forkheadbox L2) were coexpressed in pre-granulosa cells of female chicken embryonic gonads, while FOXL2 did not affect aromatase expression at embryonic stages. Second, our research showed that CYP19A1, ESR1 (estrogen receptor alpha), ESR2 (estrogen receptor beta) and NR5A2 (liver receptor homologue-1) were coexpressed in the theca cell layers of chicken small yellow follicles. There was cross-talk between CYP19A1 and candidate transcription factors (ESR1, ESR2 and NR5A2), which was identified by generating a reliable theca cell culture model. Using luciferase assays in theca cells and chicken embryonic fibroblast (DF-1) cells, the results suggested that ESR1 and NR5A2 had potential effects on CYP19A1 promoter activity in chickens. Overexpression of ESR1, ESR2 and NR5A2 in chicken embryonic fibroblast (DF-1) cells upregulated the protein expression of CYP19A1, mutually restricted each other and formed a potential regulatory network to coordinate the expression of CYP19A1. To conclude, our results indicated that FOXL2 cannot regulate the expression of CYP19A1 at chicken embryonic stages and after sexual maturity, ESR1, ESR2 and NR5A2 form a functional network to affect the expression of CYP19A1. These results laid a foundation for further research on the transcriptional regulation of chicken aromatase.

Inositols: From Established Knowledge to Novel Approaches

Myo-inositol (myo-Ins) and D-chiro-inositol (D-chiro-Ins) are natural compounds involved in many biological pathways. Since the discovery of their involvement in endocrine signal transduction, myo-Ins and D-chiro-Ins supplementation has contributed to clinical approaches in ameliorating many gynecological and endocrinological diseases. Currently both myo-Ins and D-chiro-Ins are well-tolerated, effective alternative candidates to the classical insulin sensitizers, and are useful treatments in preventing and treating metabolic and reproductive disorders such as polycystic ovary syndrome (PCOS), gestational diabetes mellitus (GDM), and male fertility disturbances, like sperm abnormalities. Moreover, besides metabolic activity, myo-Ins and D-chiro-Ins deeply influence steroidogenesis, regulating the pools of androgens and estrogens, likely in opposite ways. Given the complexity of inositol-related mechanisms of action, many of their beneficial effects are still under scrutiny. Therefore, continuing research aims to discover new emerging roles and mechanisms that can allow clinicians to tailor inositol therapy and to use it in other medical areas, hitherto unexplored. The present paper outlines the established evidence on inositols and updates on recent research, namely concerning D-chiro-Ins involvement into steroidogenesis. In particular, D-chiro-Ins mediates insulin-induced testosterone biosynthesis from ovarian thecal cells and directly affects synthesis of estrogens by modulating the expression of the aromatase enzyme. Ovaries, as well as other organs and tissues, are characterized by a specific ratio of myo-Ins to D-chiro-Ins, which ensures their healthy state and proper functionality. Altered inositol ratios may account for pathological conditions, causing an imbalance in sex hormones. Such situations usually occur in association with medical conditions, such as PCOS, or as a consequence of some pharmacological treatments. Based on the physiological role of inositols and the pathological implications of altered myo-Ins to D-chiro-Ins ratios, inositol therapy may be designed with two different aims: (1) restoring the inositol physiological ratio; (2) altering the ratio in a controlled way to achieve specific effects.

ERβ Regulation of Gonadotropin Responses during Folliculogenesis

Gonadotropins are essential for regulating ovarian development, steroidogenesis, and gametogenesis. While follicle stimulating hormone (FSH) promotes the development of ovarian follicles, luteinizing hormone (LH) regulates preovulatory maturation of oocytes, ovulation, and formation of corpus luteum. Cognate receptors of FSH and LH are G-protein coupled receptors that predominantly signal through cAMP-dependent and cAMP-independent mechanisms that activate protein kinases. Subsequent vital steps in response to gonadotropins are mediated through activation or inhibition of transcription factors required for follicular gene expression. Estrogen receptors, classical ligand-activated transcriptional regulators, play crucial roles in regulating gonadotropin secretion from the hypothalamic-pituitary axis as well as gonadotropin function in the target organs. In this review, we discuss the role of estrogen receptor β (ERβ) regulating gonadotropin response during folliculogenesis. Ovarian follicles in Erβ knockout (Erβ^KO) mutant female mice and rats cannot develop beyond the antral state, lack oocyte maturation, and fail to ovulate. Theca cells (TCs) in ovarian follicles express LH receptor, whereas granulosa cells (GCs) express both FSH receptor (FSHR) and LH receptor (LHCGR). As oocytes do not express the gonadotropin receptors, the somatic cells play a crucial role during gonadotropin induced oocyte maturation. Somatic cells also express high levels of estrogen receptors; while TCs express ERα and are involved in steroidogenesis, GCs express ERβ and are involved in both steroidogenesis and folliculogenesis. GCs are the primary site of ERβ-regulated gene expression. We observed that a subset of gonadotropin-induced genes in GCs, which are essential for ovarian follicle development, oocyte maturation and ovulation, are dependent on ERβ. Thus, ERβ plays a vital role in regulating the gonadotropin responses in ovary.

High-precision targeting workflow for volume electron microscopy

Cells are 3D objects. Therefore, volume EM (vEM) is often crucial for correct interpretation of ultrastructural data. Today, scanning EM (SEM) methods such as focused ion beam (FIB)-SEM are frequently used for vEM analyses. While they allow automated data acquisition, precise targeting of volumes of interest within a large sample remains challenging. Here, we provide a workflow to target FIB-SEM acquisition of fluorescently labeled cells or subcellular structures with micrometer precision. The strategy relies on fluorescence preservation during sample preparation and targeted trimming guided by confocal maps of the fluorescence signal in the resin block. Laser branding is used to create landmarks on the block surface to position the FIB-SEM acquisition. Using this method, we acquired volumes of specific single cells within large tissues such as 3D cultures of mouse mammary gland organoids, tracheal terminal cells in Drosophila melanogaster larvae, and ovarian follicular cells in adult Drosophila, discovering ultrastructural details that could not be appreciated before.

Histomorphometric and immunohistochemical changes in interstitial cells and ovarian follicles of rats with polycystic ovaries treated with clomiphene citrate

OBJECTIVE

To evaluate the histomorphometric and immunohistochemical changes in interstitial cells and ovarian follicles of rats treated with clomiphene citrate during and after induction of permanent estrus.

METHODS

Twenty four adult-female rats with regular estrous cycle were equally divided into three groups: (1) GCtrl-at estrous phase. (2) GPCOS-at permanent-estrous phase. (3) GCC-PCOS rats, which remained exposed to 60 days of continuous illumination and treated with Clomiphene Citrate. After that, the animals were euthanized, and the ovaries were removed and processed for paraffin embedding. Sections were stained with H.E. for histomorphometry or subjected to immunohistochemistry for Ki-67 and cleaved caspase-3 detections.

RESULTS

The GPCOS showed lack of corpus luteum and several ovarian cysts, as well as interstitial-like cells. The presence of corpus luteum and a significant increase in primary and antral follicles were observed in GCC, which also showed a decrease in the number of ovarian cysts and in the area occupied by interstitial-like cells, as well as a decrease in nuclear volume of interstitial cells. The percentage of cell proliferation was significantly higher in granulosa cells of the GCC. On the other hand, the percentage of apoptosis was significantly higher in the granulosa cells of GPCOS than the GCC.

CONCLUSION

The ovaries of rats treated with clomiphene citrate showed a decrease in the number of cysts, an increase in the number of ovarian follicles, the presence of corpus luteum along with a decrease in the nuclear volume in the area occupied by interstitial cells.

Discovery of a possible role of asprosin in ovarian follicular function

Asprosin is a novel fasting-induced protein encoded by fibrillin-1 (FBN1) gene, produced when FBN1 is cleaved by the enzyme furin, and is associated with insulin resistance and polycystic ovarian syndrome in humans. To characterize mRNA abundance of FBN1, FURIN, and the presumed asprosin receptor, olfactory receptor family 4 subfamily M member 1 (OR4M1) in granulosa (GC) and theca cells (TC), and identify hormones regulating FBN1 mRNA expression, GC and TC from small (1-5 mm; SM) and large (>8 mm; LG) follicles were collected from ovaries of heifers obtained at an abattoir and used for real-time PCR gene expression analysis or in vitro evaluation of hormone regulation and asprosin effects. SMTC had 151-fold greater (P < 0.05) FBN1 mRNA abundance than SMGC, and LGTC had 50-fold greater FBN1 mRNA than LGGC. In contrast, OR4M1 mRNA was 81-fold greater in SMGC than LGGC and did not differ from SMTC, but LGTC had 9-fold greater OR4M1 mRNA than LGGC. FURIN mRNA was 2.6-fold greater in SMTC than SMGC, but did not differ among follicular sizes. In cultured TC, leptin, insulin, LH, IGF1 and steroids did not affect FBN1 mRNA, but TGFB1 increased (P < 0.05) FBN1 mRNA by 2.2-fold; EGF and FGFs increased FBN1 mRNA by 1.3- to 1.5-fold. Asprosin enhanced LH-induced TC androstenedione production, reduced IGF1-induced TC proliferation, and had no effect on progesterone production. Developmental regulation of FBN1, FURIN and OR4M1 along with direct effects of asprosin on TC suggests that asprosin may be a novel regulator of ovarian follicular function.

Bisphenol S enhances gap junction intercellular communication in ovarian theca cells

Gap junction intercellular communication (GJIC) is necessary for ovarian function, and it is temporospatially regulated during follicular development and ovulation. At outermost layer of the antral follicle, theca cells provide structural, steroidogenic, and vascular support. Inter- and extra-thecal GJIC is required for intrafollicular trafficking of signaling molecules. Because GJIC can be altered by hormones and endocrine disrupting chemicals (EDCs), we tested if any of five common EDCs (bisphenol A (BPA), bisphenol S (BPS), bisphenol F (BPF), perfluorooctanesulfonic acid (PFOS), and triphenyltin chloride (TPT)) can interfere with theca cell GJIC. Since most chemicals are reported to repress GJIC, we hypothesized that all chemicals tested, within environmentally relevant human exposure concentrations, will inhibit theca cell GJICs. To evaluate this hypothesis, we used a scrape loading/dye transfer assay. BPS, but no other chemical tested, enhanced GJIC in a dose- and time-dependent manner in ovine primary theca cells. A signal-protein inhibitor approach was used to explore the GJIC-modulatory pathways involved. Phospholipase C and mitogen-activated protein kinase (MAPK) inhibitors significantly attenuated BPS-induced enhanced GJIC. Human theca cells were used to evaluate translational relevance of these findings. Human primary theca cells had a ∼40% increase in GJIC in response to BPS, which was attenuated with a MAPK inhibitor, suggestive of a conserved mechanism. Upregulation of GJIC could result in hyperplasia of the theca cell layer or prevent ovulation by holding the oocyte in meiotic arrest. Further studies are necessary to understand in vitro to in vivo translatability of these findings on follicle development and fertility outcomes.

Wilms' tumor (WT1) (±KTS) variants decreases the progesterone secretion of bovine ovarian theca cells

Wilms' tumor gene WT1 encodes a nuclear transcriptional factor, which has been shown to regulate granulosa cell steroidogenesis in bovine; however, it is not known whether the functions of theca cells are regulated by WT1. Here, we determined the effects of this gene on theca cell proliferation, apoptosis, and steroidogenesis in vitro. In cultured bovine theca cells, the downregulation of WT1 increased the secretion of progesterone but had no effect on proliferation and apoptosis. WT1 includes the variants WT1(+KTS) and WT1(-KTS), which differ by 3 amino acids KTS (lysine, threonine, and serine). WT1(±KTS) upregulation increased the messenger RNA (mRNA) expression of STAR and CYP17A1 and decreased the progesterone secretion and CYP11A1 mRNA expression. In contrast to WT1(+KTS), WT1(-KTS) upregulation also decreased the mRNA expression of 3β-HSD. In both variants, WT1(-KTS) has more obvious effects. In conclusion, WT1 can decrease progesterone secretion, likely due in part to the inhibition of CYP11A1 and 3β-HSD.

Effects of IL-18 on the proliferation and steroidogenesis of bovine theca cells: Possible roles in the pathogenesis of polycystic ovary syndrome

Interleukin 18 (IL-18) is a pleiotropic pro-inflammatory cytokine and is associated with arrested follicle development and anovulation which are the typical pathological changes of PCOS. Theca cells (TCs) have a key role in follicular growth and atresia. But whether IL-18 can directly affect ovarian TCs function is unknown. Therefore, the objective of this study was to determine the effect of IL-18 on proliferation and steroidogenesis of bovine TCs and to explore the biological effect of IL-18 on folliculogenesis. This work revealed that at 300-1000 pg/mL, IL-18 led to a time- and dose-dependently increase in cell proliferation (P < .05). IL-18 increased 17-hydroxyprogesterone (17OHP4) and androstenedione (A2) secretion with up-regulation of key steroidogenesis-related genes CYP11A1 and CYP17A1 (P < .05). Furthermore, our data demonstrated that the IL-18R protein is predominantly expressed in small-follicle (3-6 mm) TCs than large follicles (8-22 mm) by immunohistochemistry. We also found that the stimulation effects of IL-18 on TCs can be reversed with the addition of IL-18BP as early as at 4 hours of culture and reached the peak at 16 hours. We conclude that IL-18 appears to target TCs in bovine, and suggest an important role for this cytokine in ovarian function. Present findings further validate potential effects of IL-18 in the conditions associated with follicular dysplasia and excessive growth of ovarian TCs (such as PCOS). But additional research is needed to further understand the mechanism of action of IL-18 in theca cells as well as its precise role in folliculogenesis.

Core clock gene Bmal1 deprivation impairs steroidogenesis in mice luteinized follicle cells

Luteinization is the event of corpus luteum formation, a way of follicle cells transformation and a process of steroidogenesis alteration. As the core clock gene, Bmal1 was involved in the regulation of ovulation process and luteal function afterwards. Till now, the underlying roles of luteinization played by Bmal1 remain unknown. To explore the unique role of Bmal1 in luteal steroidogenesis and its underlying pathway, we investigated the luteal hormone synthesis profile in Bmal1 knockout female mice. We found that luteal hormone synthesis was notably impaired, and phosphorylation of PI3K/NfκB pathway was significantly activated. Then, the results were verified in in vitro cultured cells, including isolated Bmal1 interference granulosa cells (GCs) and theca cells (TCs), respectively. Hormones levels of supernatant culture media and mRNA expressions of steroidogenesis-associated genes (star, Hsd3β2, cyp19a1 in GCs, Lhcgr, star, Hsd3β2, cyp17a1 in TCs) were mutually decreased, while the phosphorylation of PI3K/NfκB was promoted during in vitro luteinization. After PI3K specific-inhibitor LY294002 intervention, mRNA expressions of Lhcgr and Hsd3β2 were partially rescued in Bmal1 interference TCs, together with significantly increased androstenedione and T synthesis. Further exploration in TCs demonstrated BMAL1 interacted directly but negatively with NfκB p65 (RelA), a subunit which was supposed as a mediator in Bmal1-governed PI3K signaling regulation. Taken together, we verified the novel role of Bmal1 in luteal steroidogenesis, achieving by negative interplay with RelA-mediated PI3K/NfκB pathway.

MALDI-TOF Mass Spectrometry Revealed Significant Lipid Variations in Follicular Fluid and Somatic Follicular Cells but Not in Enclosed Oocytes between the Large Dominant and Small Subordinate Follicles in Bovine Ovary

Lipid metabolism in ovarian follicular cells supports the preparation of an enclosed oocyte to ovulation. We aimed to compare lipid composition of a dominant large follicle (LF) and subordinated small follicles (SFs) within the same ovaries. Mass spectrometry imaging displayed the differences in the distribution of several lipid features between the different follicles. Comparison of lipid fingerprints between LF and SF by Matrix Assisted Laser Desorption/Ionisation Time-Of-Flight (MALDI-TOF) mass spectrometry revealed that in the oocytes, only 8 out of 468 detected lipids (1.7%) significantly changed their abundance (p < 0.05, fold change > 2). In contrast, follicular fluid (FF), granulosa, theca and cumulus cells demonstrated 55.5%, 14.9%, 5.3% and 9.8% of significantly varied features between LF and SF, respectively. In total, 25.2% of differential lipids were identified and indicated potential changes in membrane and signaling lipids. Tremendous changes in FF lipid composition were likely due to the stage specific secretions from somatic follicular cells that was in line with the differences observed from FF extracellular vesicles and gene expression of candidate genes in granulosa and theca cells between LF and SF. In addition, lipid storage in granulosa and theca cells varied in relation to follicular size and atresia. Differences in follicular cells lipid profiles between LF and SF may probably reflect follicle atresia degree and/or accumulation of appropriate lipids for post-ovulation processes as formation of corpus luteum. In contrast, the enclosed oocyte seems to be protected during final follicular growth, likely due in part to significant lipid transformations in surrounding cumulus cells. Therefore, the enclosed oocyte could likely keep lipid building blocks and energy resources to support further maturation and early embryo development.

Developmental Programming: Sheep Granulosa and Theca Cell-Specific Transcriptional Regulation by Prenatal Testosterone

Prenatal testosterone (T)-treated sheep, similar to polycystic ovarian syndrome women, manifest reduced cyclicity, functional hyperandrogenism, and polycystic ovary (PCO) morphology. The PCO morphology results from increased follicular recruitment and persistence of antral follicles, a consequence of reduced follicular growth and atresia, and is driven by cell-specific gene expression changes that are poorly understood. Therefore, using RNA sequencing, cell-specific transcriptional changes were assessed in laser capture microdissection isolated antral follicular granulosa and theca cells from age 21 months control and prenatal T-treated (100 mg intramuscular twice weekly from gestational day 30 to 90; term: 147 days) sheep. In controls, 3494 genes were differentially expressed between cell types with cell signaling, proliferation, extracellular matrix, immune, and tissue development genes enriched in theca; and mitochondrial, chromosomal, RNA, fatty acid, and cell cycle process genes enriched in granulosa cells. Prenatal T treatment 1) increased gene expression of transforming growth factor β receptor 1 and exosome component 9, and decreased BCL6 corepressor like 1, BCL9 like, and MAPK interacting serine/threonine kinase 2 in both cells, 2) induced differential expression of 92 genes that included increased mitochondrial, ribosome biogenesis, ribonucleoprotein, and ubiquitin, and decreased cell development and extracellular matrix-related pathways in granulosa cells, and 3) induced differential expression of 56 genes that included increased noncoding RNA processing, ribosome biogenesis, and mitochondrial matrix, and decreased transcription factor pathways in theca cells. These data indicate that follicular function is affected by genes involved in transforming growth factor signaling, extracellular matrix, mitochondria, epigenetics, and apoptosis both in a common as well as a cell-specific manner and suggest possible mechanistic pathways for prenatal T treatment-induced PCO morphology in sheep.

Inhibition of autophagy in theca cells induces CYP17A1 and PAI-1 expression via ROS/p38 and JNK signalling during the development of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a clinical syndrome characterized by hyperandrogenism, oligo/anovulation, and polycystic ovary. Autophagy is an intracellular system that degrades cytosolic proteins and organelles. The relationship between autophagy and PCOS has not been clarified. We found that p62 and ubiquitin were significantly increased in theca cells of women with PCOS using immunohistochemistry. Autophagy inhibition by palmitic acid and chloroquine in bovine theca cells increased p62 and ubiquitin and induced the expression of cytochrome P450 17A1 (CYP17A1) and plasminogen activator inhibitor-1 (PAI-1) mRNA. Furthermore, palmitic acid and chloroquine exposure significantly increased reactive oxygen species (ROS) and activated p38 and c-Jun N-terminal kinase (JNK). Inhibition of p38 and JNK significantly reduced CYP17A1 and PAI-1 mRNA expression. We showed that inhibition of autophagy in theca cells may have contributed to the pathogenesis of PCOS, based on CYP17A1 and PAI-1 mRNA expression via the ROS/p38 and JNK signalling pathways.

A grape seed extract maternal dietary supplementation improves egg quality and reduces ovarian steroidogenesis without affecting fertility parameters in reproductive hens

In broiler hens, the genetic selection increased susceptibility to metabolic disorders and reproductive dysfunctions. In human ovarian cells, grape seed extracts (GSE) improved steroid production. Here, we investigated the effects of a GSE dietary supplementation on egg production and quality, fertility parameters, Reactive Oxygen Species (ROS) and steroid content in yolk egg associated to plasma adipokines in broiler hens. For this, we designed two in vivo experiments, the first one included three groups of hens: A (control), B and C (supplemented with GSE at 0.5% and 1% of the total diet composition, respectively, since week 4), and the second one used two groups of hens: A (control) and D (supplemented with GSE at 1% of the total diet composition since hatching). We assessed the egg production from 23^th to 40^th weeks and quality at 33^th week. After artificial inseminations, the fertility parameters were calculated. In egg yolk, Reactive Oxygen Species (ROS) level and steroid production were evaluated by Ros-Glo H202 and ELISA assay, respectively. Expression of steroidogenic enzymes and adipokines and their receptors was determined by RT-qPCR in ovarian cells and plasma adipokines (RARRES2, ADIPOQ and NAMPT) were evaluated by specific ELISA assays. The fertility parameters and egg production were unaffected by GSE supplementation whatever the experiment (exp.). However, the rate of double-yolk eggs decreased for all GSE supplemented groups (exp. 1 P <0.01, exp.2, P<0.02). In exp.1, C group eggs were bigger and larger (P<0.0001) and the shell elasticity was higher for both B and C (P<0.0003) as compared to control. In the egg yolk, GSE supplementation in both exp. reduced ROS content and steroidogenesis consistent with a decrease in P450 aromatase and StAR mRNA expression and basal in vitro progesterone secretion in granulosa cells (P<0.001). Interestingly, in both exp. RARRES2 plasma levels were positively correlated while ADIPOQ and NAMPT plasma levels were negatively correlated, with steroids and ROS in yolk (P<0.0001). Taken together, maternal dietary GSE supplementation did not affect egg production and fertility parameters whereas it reduced ROS content and steroidogenesis in yolk egg. Furthermore, it ameliorated egg quality by decreasing the number of double-yolk eggs and by improving the size of normal eggs and the elasticity of the shell. Taken together, our data suggest the possibility of using dietary maternal GSE to improve egg quality.

Androgen production in response to LH is impaired in theca cells from nonovulatory dominant follicles in early-postpartum dairy cows

Most dairy cows develop a dominant follicle within two weeks postpartum, but 60% of these follicles fail to ovulate. In a previous study, we determined that cows destined to ovulate have higher LH pulse frequency and circulating estradiol. The latter characteristic provided a method for distinguishing ovulatory from nonovulatory follicles during development and we found that nonovulatory follicles have lower estradiol and androstenedione in their follicular fluid. We hypothesized that lower LH pulse frequency impairs androgen production by theca cells of nonovulatory cows, reducing their ability to make estradiol. In the present study, we applied our method for predicting follicle fate to collect dominant follicles from predicted ovulatory (n = 7) and nonovulatory (n = 3) follicles. Theca and granulosa cells were separated and cultured in the absence or presence of LH, FSH, and/or testosterone for three days, with daily collection of culture medium for steroid RIAs. Estradiol and progesterone production by granulosa cells were not different between ovulatory and nonovulatory follicles. By contrast, overall androstenedione production by theca cells from ovulatory follicles was significantly higher compared with nonovulatory follicles on all three days of culture and, as culture progressed, theca from nonovulatory follicles had increasingly poorer responses to LH. In the same cultures, the progesterone production by theca cells was similar in ovulatory and nonovulatory groups. In support of our hypothesis, the results show that estradiol production by granulosa cells from nonovulatory follicles is robust when androgen substrate is present, but that thecal androgen production in response to LH is impaired. This suggests that the initial defect in steroidogenesis in dominant follicles that fail to ovulate postpartum is lower production of androgen by theca cells.

Regulation of the transcription factor E2F8 gene expression in bovine ovarian cells

Overexpression of the transcription factor, E2F8, has been associated with ovarian cancer. Objectives of this study were to determine: 1) if E2F8 gene expression in granulosa cells (GC) and theca cells (TC) change with follicular development, and 2) if E2F8 mRNA abundance in TC and GC is hormonally regulated. Using real-time PCR, E2F8 mRNA abundance in GC and TC was greater (P < 0.05) in small than large follicles. FGF9 induced an increase (P < 0.05) in E2F8 mRNA abundance by 1.6- to 7-fold in large-follicle (8-20 mm) TC and GC as well as in small-follicle (1-5 mm) GC. Abundance of E2F8 mRNA in TC was increased (P < 0.05) with FGF2, FGF9 or VEGFA treatments alone in vitro, and concomitant treatment of VEGFA with FGF9 increased (P < 0.05) abundance of E2F8 mRNA above any of the singular treatments; BMP4, WNT3A and LH were without effect. IGF1 amplified the stimulatory effect of FGF9 on E2F8 mRNA abundance by 2.7-fold. Collectively, our studies show for the first time that follicular E2F8 is developmentally and hormonally regulated indicating that E2F8 may be involved in follicular development.

Inflammatory Stimuli Trigger Increased Androgen Production and Shifts in Gene Expression in Theca-Interstitial Cells

Polycystic ovary syndrome (PCOS) is a common reproductive endocrine disorder characterized by theca cell hyperplasia and excessive androgen production. An increasing body of evidence has pointed to a close association between PCOS and low-grade chronic systemic inflammation. However, the mechanistic basis for this linkage is unknown. Therefore, we evaluated the effects of the inflammatory agents lipopolysaccharide (LPS) and IL-1β on rat theca-interstitial cells (TICs). We found that incubation with either LPS or IL-1β elicited a dose-dependent increase in both TIC viability and androgen production. Using RNA sequencing analysis, we found that both of these inflammatory agents also triggered profound and widespread shifts in gene expression. Using a stringent statistical cutoff, LPS and IL-1β elicited differential expression of 5201 and 5953 genes, respectively. Among the genes upregulated by both LPS and IL-1β were key regulatory genes involved in the cholesterol and androgen biosynthesis pathways, including Cyp17a1, Cyp11a1, Hsd3b, and Hmgcr. This provides a molecular explanation for the mechanism of action of inflammatory agents leading to increased androgen production. Gene ontology and pathway analysis revealed that both LPS and IL-1β regulated genes highly enriched for many common functions, including the immune response and apoptosis. However, a large number of genes (n = 2222) were also uniquely regulated by LPS and IL-1β, indicating that these inflammatory mediators have substantial differences in their mechanism of action. Together, these findings highlight the potential molecular mechanisms through which chronic low-grade inflammation contributes to the pathogenesis of androgen excess in PCOS.

miRNA Profiling Reveals miRNA-130b-3p Mediates DENND1A Variant 2 Expression and Androgen Biosynthesis

Polycystic ovary syndrome (PCOS) is a common endocrine disorder of reproductive-age women involving overproduction of ovarian androgens and, in some cases, from the adrenal cortex. Family studies have established that PCOS is a complex heritable disorder with genetic and epigenetic components. Several small, noncoding RNAs (miRNAs) have been shown to be differentially expressed in ovarian cells and follicular fluid and in the circulation of women with PCOS. However, there are no reports of global miRNA expression and target gene analyses in ovarian theca cells isolated from normal cycling women and women with PCOS, which are key to the elucidation of the basis for the hyperandrogenemia characteristic of PCOS. With the use of small RNA deep sequencing (miR-seq), we identified 18 differentially expressed miRNAs in PCOS theca cells; of these, miR-130b-3p was predicted to target one of the PCOS genome-wide association study candidates, differentially expressed in neoplastic vs normal cells domain containing 1A (DENND1A). We previously reported that DENND1A variant 2 (DENND1A.V2), a truncated isoform of DENND1A, is upregulated in PCOS theca cells and mediates augmented androgen biosynthesis in PCOS theca cells. The comparison of miR-130b-3p in normal and PCOS theca cells demonstrated decreased miR-130b-3p expression in PCOS theca cells, which was correlated with increased DENND1A.V2, cytochrome P450 17α-hydroxylase (CYP17A1) mRNA and androgen biosynthesis. miR-130b-3p mimic studies established that increased miR130b-3p is correlated with decreased DENND1A.V2 and CYP17A1 expression. Thus, in addition to genetic factors, post-transcriptional regulatory mechanisms via miR-130b-3p underly androgen excess in PCOS. Ingenuity® Pathway Analysis Core Pathway and Network Analyses suggest a network by which miR-130b-3p, DENND1A, the luteinizing hormone/choriogonadotropin receptor, Ras-related protein 5B, and signaling pathways that they potentially target may mediate hyperandrogenism in PCOS.

VCAM1 Is Induced in Ovarian Theca and Stromal Cells in a Mouse Model of Androgen Excess

Ovarian theca androgen production is regulated by the pituitary LH and intrafollicular factors. Enhanced androgen biosynthesis by theca cells contributes to polycystic ovary syndrome (PCOS) in women, but the ovarian consequences of elevated androgens are not completely understood. Our study documents the molecular events that are altered in the theca and stromal cells of mice exposed to high androgen levels, using the nonaromatizable androgen DHT. Changes in ovarian morphology and function were observed not only in follicles, but also in the stromal compartment. Genome-wide microarray analyses revealed marked changes in the ovarian transcriptome of DHT-treated females within 1 week. Particularly striking was the increased expression of vascular cell adhesion molecule 1 (Vcam1) specifically in the NR2F2/COUPTF-II lineage theca cells, not granulosa cells, of growing follicles and throughout the stroma of the androgen-treated mice. This response was mediated by androgen receptors (ARs) present in theca and stromal cells. Human theca-derived cultures expressed both ARs and NR2F2 that were nuclear. VCAM1 mRNA and protein were higher in PCOS-derived theca cells compared with control theca and reduced markedly by the AR antagonist flutamide. In the DHT-treated mice, VCAM1 was transiently induced by equine chorionic gonadotropin, when androgen and estrogen biosynthesis peak in preovulatory follicles, and was potently suppressed by a superovulatory dose of human chorionic gonadotropin. High levels of VCAM1 in the theca and interstitial cells of DHT-treated mice and in adult Leydig cells indicate that there may be novel functions for VCAM1 in reproductive tissues, including the gonads.

Physiological and Pathological Androgen Actions in the Ovary

Androgens, although traditionally thought to be male sex steroids, play important roles in female reproduction, both in healthy and pathological states. This mini-review focuses on recent advances in our knowledge of the role of androgens in the ovary. Androgen receptor (AR) is expressed in oocytes, granulosa cells, and theca cells, and is temporally regulated during follicular development. Mouse knockout studies have shown that AR expression in granulosa cells is critical for normal follicular development and subsequent ovulation. In addition, androgens are involved in regulating dynamic changes in ovarian steroidogenesis that are critical for normal cycling. Androgen effects on follicle development have been incorporated into clinical practice in women with diminished ovarian reserve, albeit with limited success in available literature. At the other extreme, androgen excess leads to disordered follicle development and anovulatory infertility known as polycystic ovary syndrome (PCOS), with studies suggesting that theca cell AR may mediate many of these negative effects. Finally, both prenatal and postnatal animal models of androgen excess have been developed and are being used to study the pathophysiology of PCOS both within the ovary and with regard to overall metabolic health. Taken together, current scientific consensus is that a careful balance of androgen activity in the ovary is necessary for reproductive health in women.

Transcript abundance of stromal and thecal cell related genes during bovine ovarian development

Movement and expansion of mesonephric-derived stroma appears to be very important in the development of the ovary. Here, we examined the expression of 24 genes associated with stroma in fetal ovaries during gestation (n = 17; days 58-274) from Bos taurus cattle. RNA was isolated from ovaries for quantitative RT-PCR. Expression of the majority of genes in TGFβ signalling, stromal transcription factors (NR2F2, AR), and some stromal matrix genes (COL1A1, COL3A1 and FBN1, but not FBN3) showed a positive linear increase with gestational age. Expression of genes associated with follicles (INSL3, CYP17A1, CYP11A1 and HSD3B1), was low until mid-gestation and then increased with gestational age. LHCGR showed an unusual bimodal pattern; high levels in the first and last trimesters. RARRES1 and IGFBP3 also increased with gestational age. To relate changes in gene expression in stromal cells with that in non stromal cells during development of the ovary we combined the data on the stromal genes with another 20 genes from non stromal cells published previously and then performed hierarchical clustering analysis. Three major clusters were identified. Cluster 1 genes (GATA4, FBN3, LHCGR, CYP19A1, ESR2, OCT4, DSG2, TGFB1, CCND2, LGR5, NR5A1) were characterised by high expression only in the first trimester. Cluster 2 genes (FSHR, INSL3, HSD3B1, CYP11A1, CYP17A1, AMH, IGFBP3, INHBA) were highly expressed in the third trimester and largely associated with follicle function. Cluster 3 (COL1A1, COL3A1, FBN1, TGFB2 TGFB3, TGFBR2, TGFBR3, LTBP2, LTBP3, LTBP4, TGFB1I1, ALDH1A1, AR, ESR1, NR2F2) had much low expression in the first trimester rising in the second trimester and remaining at that level during the third trimester. Cluster 3 contained members of two pathways, androgen and TGFβ signalling, including a common member of both pathways namely the androgen receptor cofactor TGFβ1 induced transcript 1 protein (TGFB1I1; hic5). GATA4, FBN3 and LHCGR, were highly correlated with each other and were expressed highly in the first trimester during stromal expansion before follicle formation, suggesting that this could be a critical phase in the development of the ovarian stroma.

Paeoniflorin extract reverses dexamethasone-induced testosterone over-secretion through downregulation of cytochrome P450 17A1 expression in primary murine theca cells

ETHNOPHARMACOLOGICAL RELEVANCE

Polycystic Ovarian Syndrome (PCOS) is a complex endocrine and reproductive disorder. A main hallmark includes increased androgen production. The root of Paeonia lactiflora Pall. (Bai Shao) is used in Chinese herbal medicine for reproductive disorders, however its effects and mechanisms on ovarian theca cells has not yet been fully elucidated.

AIM OF THE STUDY

The aim of this study was to evaluate effect of paeoniflorin extract (PFE), the main constituents of Bai Shao, on androgen production in ovarian theca cells.

MATERIALS AND METHODS

Primary murine theca cells were treated with concentrations of PFE (1-100 µg/mL) in the presence of dexamethasone (10 µM) with media-only treated cells used as the control. After 24 h, culture media was collected for biochemistry assays of testosterone and progesterone. Expression of key steroidogenic enzymes, cholesterol side-chain cleavage (CYP11A1) and 17α-hydroxylase (CYP17A1) was characterized using immunofluorescence staining, immunoblotting and qRT-PCR.

RESULTS

Dexamethasone significantly enhanced testosterone secretion (P < 0.05 vs. the control cells). PFE reversed over-production of testosterone induced by dexamethasone in a dose-dependent manner. The treatment with PFE also normalized production of progesterone in dexamethasone-treated cells. Expression of CYP11A1 and CYP17A1 in the theca cells were visualised by immunofluorescence staining. All doses of PFE significantly inhibited CYP17A1 expression detected by immunoblotting, but only 100 µg/mL of PFE downregulated CYP11A1 expression and reduced CYP11A1 significantly in dexamethasone-treated theca cells.

CONCLUSIONS

PFE may reduce over-secretion of testosterone in theca cells through downregulation of CYP17A1 and CYP11A1. These findings provide scientific evidence to treat ovarian hyperandrogenism with the root of Paeonia lactiflora Pall.

Expression dynamics of gonadotropin-releasing hormone-I and its mutual regulation with luteinizing hormone in chicken ovary and follicles

Gonadotropin-releasing hormone-I (GnRH-I) has been identified in the ovaries of vertebrate species, and this decapeptide is a key regulator of reproductive functions. However, its biological action and regulatory mechanism in the chicken ovary remain to be characterized. In this study, the expression of GnRH-I gene in chicken hypothalamus and ovaries at different developmental stages and different sizes of follicles was investigated, and the effect of GnRH-I mRNA on chicken follicular cells was analyzed in vitro. The results showed that the expression of GnRH-I was dramatically decreased in the hen ovary compared to that in the hypothalamus after sexual maturation. In the mature ovarian follicles, GnRH-I mRNA levels were significantly higher in theca cells than that in granulosa cells. Overexpression of GnRH-I decreased the expression of luteinizing hormone receptor (LHR) mRNA in theca cells from preovulatory follicles but had no effect on granulosa cells. Treatment of theca cells with different concentrations of luteinizing hormone (LH) significantly increased GnRH-I mRNA expression at low doses (50 ng/ml) but significantly decreased it at higher doses (200 ng/ml). Furthermore, GnRH-I inhibited LH-induced LHR expression at the lower dose of LH (50 ng/ml). These findings provide strong evidence indicating that GnRH-I is an important regulator in the chicken ovary.

SIRT2 plays a novel role on progesterone, estradiol and testosterone synthesis via PPARs/LXRα pathways in bovine ovarian granular cells

SIRT2 has been shown to possess NAD⁺-dependent deacetylase and desuccinylase enzymatic activities, it also regulates metabolism homeostasis in mammals. Previous data has suggested that resveratrol, a potential activator of Sirtuins, played a stimulation role in steroidogenesis. Unfortunately, to date, the physiological roles of SIRT2 in ovarian granular cells (GCs) are largely unknown. Here, we studied the function and molecular mechanisms of SIRT2 on steroid hormone synthesis in GCs from Qinchuan cattle. Immunohistochemistry and western blotting showed that SIRT2 was expressed not only in GCs and cumulus cells, but also in oocytes and theca cells. We found that the secretion of progesterone was induced, whereas that of estrogen and testosterone secretion was suppressed by treatment with the SIRT2 inhibitor (Thiomyristoyl or SirReal2) or siRNA. Additionally, the PPARs/LXRα signaling pathways were suppressed by SIRT2 siRNA or inhibitors. The mRNA expression of CYP17, aromatase and StAR was suppressed, but the abundance of CYP11A1 mRNA was induced by SIRT2 inhibition. Furthermore, the PPARα agonist or PPARγ antagonist could mimic the effects of SIRT2 inhibition on hormones levels and gene expression associated with steroid hormone biosynthesis. In turn, those effects were abolished by the LXRα agonist (LXR-623). Together, these data support the hypothesis that SIRT2 regulates steroid hormone synthesis via the PPARs/LXRα pathways in GCs.

Effects of fibroblast growth factors and the transcription factor, early growth response 1, on bovine theca cells

The theca cell layer of the ovarian follicle secretes growth factors that impact the function of granulosa cells. One such factor is fibroblast growth factor 18 (FGF18) that causes apoptosis of granulosa cells, however it is not known if FGF18 induces apoptosis also in theca cells. Addition of recombinant FGF18 to bovine theca cells in vitro inhibited steroidogenesis but, in contrast to previous data in granulosa cells, decreased the incidence of apoptosis. FGF18 activated typical FGF signaling pathways in theca cells, which was not previously observed in granulosa cells. The transcription factor Early Growth Response-1 (EGR1) was a target of FGF18 action; overexpression and knock-down experiments demonstrated that EGR1 is a major upstream component of FGF signaling in theca cells and that it directs cell fate toward proliferation. These data suggest that FGF18 is mitogenic for theca cells while being pro-apoptotic in granulosa cells.

Myostatin is expressed in bovine ovarian follicles and modulates granulosal and thecal steroidogenesis

Myostatin plays a negative role in skeletal muscle growth regulation but its potential role in the ovary has received little attention. Here, we first examined relative expression of myostatin (MSTN), myostatin receptors (ACVR1B, ACVR2B and TGFBR1) and binding protein, follistatin (FST), in granulosa (GC) and theca (TC) cells of developing bovine follicles. Secondly, using primary GC and TC cultures, we investigated whether myostatin affects steroidogenesis and cell number. Thirdly, effects of gonadotropins and other intrafollicular factors on MSTN expression in GC and TC were examined. MSTN, ACVR1B, TGFBR1, ACVR2B and FST mRNA was detected in both GC and TC at all follicle stages. Immunohistochemistry confirmed follicular expression of myostatin protein. Interestingly, MSTN mRNA expression was lowest in GC of large oestrogen-active follicles whilst GC FST expression was maximal at this stage. In GC, myostatin increased basal CYP19A1 expression and oestradiol secretion whilst decreasing basal and FSH-induced HSD3B1 expression and progesterone secretion and increasing cell number. Myostatin also reduced IGF-induced progesterone secretion. FSH and dihydrotestosterone had no effect on granulosal MSTN expression whilst insulin-like growth factor and tumour necrosis factor-alpha suppressed MSTN level. In TC, myostatin suppressed basal and LH-stimulated androgen secretion in a follistatin-reversible manner and increased cell number, without affecting progesterone secretion. LH reduced thecal MSTN expression whilst BMP6 had no effect. Collectively, results indicate that, in addition to being potentially responsive to muscle-derived myostatin from the circulation, myostatin may have an intraovarian autocrine/paracrine role to modulate thecal and granulosal steroidogenesis and cell proliferation/survival.

Expression of Müllerian-Inhibiting Substance/Anti-Müllerian Hormone Type II Receptor in the Human Theca Cells

CONTEXT

Müllerian-inhibiting substance/anti-Müllerian hormone (MIS/AMH) is produced in the ovarian granulosa cells, and it is believed to inhibit ovarian folliculogenesis and steroidogenesis in women of reproductive age.

OBJECTIVE

To investigate the expression of MIS/AMH type II receptor (MISRII/AMHRII) that binds MIS/AMH in the ovaries of reproductive-age women; to identify the exact targets of MIS/AMH.

DESIGN

Laboratory study using human ovarian tissue.

SETTING

University hospital.

PATIENTS

Tissue samples from 25 patients who had undergone ovarian surgery.

INTERVENTIONS

The segregation of ovarian granulosa and theca cells by laser microdissection was followed by RT-PCR, analyzing MISRII/AMHRII mRNA expression. Afterward, in situ hybridization and immunohistochemistry were performed to determine the localization of MISRII/AMHRII mRNA and protein expression.

MAIN OUTCOME MEASURES

MISRII/AMHRII mRNA expression by RT-PCR, in situ hybridization, and immunohistochemistry.

RESULTS

MISRII/AMHRII were expressed in granulosa and theca cells of preantral and antral follicles. The granulosa cells showed stronger MISRII/AMHRII expression than theca cells. MISRII/AMHRII mRNA staining of granulosa and theca cells in large antral follicles, early atretic follicles, and corpus luteum waned but were still detected weakly, showing higher expression in theca cells than in granulosa cells. However, MISRII/AMHRII protein in the granulosa layer of the atretic follicle and corpus luteum could not be assessed.

CONCLUSIONS

As MISRII/AMHRII is expressed in both granulosa and theca cells, this indicates that MIS/AMH, produced in the granulosa cells, is active in the theca cells as well. MIS/AMH is most likely actively involved not only in the autocrine and endocrine processes but also in the paracrine processes involving theca cells.

Presence of anti-Müllerian hormone (AMH) during follicular development in the porcine ovary

BACKGROUND

Anti-Müllerian hormone (AMH) is expressed by granulosa cells of developing follicles and plays an inhibiting role in the cyclic process of follicular recruitment by determining follicle-stimulating hormone threshold levels. Knowledge of AMH expression in the porcine ovary is important to understand the reproductive efficiency in female pigs.

RESEARCH AIM

In the present study we investigated the expression of AMH during follicular development in prepubertal and adult female pigs by immunohistochemistry, laser capture micro-dissection and RT-qPCR.

RESULTS AND CONCLUSION

Although in many aspects the immunohistochemical localization of AMH in the porcine ovary does not differ from other species, there are also some striking differences. As in most species, AMH appears for the first time during porcine follicular development in the fusiform granulosa cells of recruited primordial follicles and continues to be present in granulosa cells up to the antral stage. By the time follicles reach the pre-ovulatory stage, AMH staining intensity increases significantly, and both protein and gene expression is not restricted to granulosa cells; theca cells now also express AMH. AMH continues to be expressed after ovulation in the luteal cells of the corpus luteum, a phenomenon unique to the porcine ovary. The physiological function of AMH in the corpus luteum is at present not clear. One can speculate that it may contribute to the regulation of the cyclic recruitment of small antral follicles. By avoiding premature exhaustion of the ovarian follicular reserve, AMH may contribute to optimization of reproductive performance in female pigs.

Luteinizing Hormone Facilitates Antral Follicular Maturation and Survival via Thecal Paracrine Signaling in Cattle

LH supplementation in assisted reproductive technology cycles improves the ongoing pregnancy rate in women with poor ovarian response (POR). However, our knowledge of the precise role of LH during the follicular phase of the menstrual cycle is incomplete. To explore the role of LH in the maturation of small antral follicles, we used an in vitro two-cell system that involved coculturing bovine granulosa cells (GCs) and theca cells (TCs) on a collagen membrane. Treatment of TCs with LH stimulated androgen production in TCs by inducing the expression of androgenic factors, subsequently increasing estrogen biosynthesis in GCs by providing androgen substrates, and inducing aromatase expression. LH stimulation of TCs induced functional LH receptor expression in GCs, a response modulated by the synthesis and action of estrogen. In the presence of TCs, LH stimulation of TCs and FSH stimulation of GCs increased the expression of IGF-1, IGF-2, and IGF-1 receptor in GCs. LH-induced expression of thecal IGF-1 protected GCs from apoptosis and promoted GC survival. Furthermore, LH stimulation of TCs increased FSH sensitivity in GCs. Thus, the LH-TC axis may be involved in the acquisition of LH dependence and the survival of small antral follicles by upregulating androgen/estrogen biosynthesis and activating the IGF system. The use of LH supplementation in ovarian stimulation may increase gonadotropin sensitivity in small antral follicles and promote follicular growth and survival by suppressing GC apoptosis and follicular atresia, resulting in multiple follicular development, even in patients with POR.

Expression and distribution of the zinc finger protein, SNAI3, in mouse ovaries and pre-implantation embryos

The Snail gene family includes Snai1, Snai2, and Snai3 that encode zinc finger-containing transcriptional repressors in mammals. The expression and localization of SNAI1 and SNAI2 have been studied extensively during folliculogenesis, ovulation, luteinization, and embryogenesis in mice. However, the role of SNAI3 is unknown. In this study, we investigated the expression of SNAI3 during these processes. Our immunohistochemistry data showed that SNAI3 first appeared in oocytes by postnatal day (PD) 9. Following this, SNAI3 was found to be expressed consistently in theca and interstitial cells, along with oocytes. In gonadotropin-treated immature mice, the expression of SNAI3 did not change significantly during follicular development. The expression of SNAI3 was reduced during ovulation, after which it increased gradually during luteinization. Similar results were obtained from western blot analyses. Furthermore, real-time polymerase chain reaction (RT-PCR) analyses revealed varying mRNA levels of different Snail factors at a given time in gonadotropin-induced ovaries. During early embryo cleavage, SNAI3 was localized to the nucleus, except the nucleolus at the germinal vesicle and one-cell stages. From two- to eight-cell stages, SNAI3 was localized only to the nucleolus. Thereafter, SNAI3 was detected only in the cytoplasm, except during the blastocyst stage when it was localized to the nucleus of the trophectoderm and the inner cell mass. RT-PCR results showed that the expression of Snail superfamily genes was decreased during the blastocyst stage. From the eight-cell to morula stage, when compaction occurs that is a prerequisite for blastocyst formation, Snai3 mRNA was expressed at very low levels and was opposite to the highest expression level of the compaction-related gene, E-cadherin, at the eight-cell stage. Taken together, our results suggest that SNAI3 likely plays some roles during folliculogenesis, luteinization, and early embryonic development.

Transcriptome profiling of bovine ovarian theca cells treated with fibroblast growth factor 9

We reported previously that fibroblast growth factor 9 (FGF9) acts as an antidifferentiation factor, stimulating proliferation of granulosa cells (GCs) and theca cells (TCs) while suppressing hormone-induced steroidogenesis of these cells. How FGF9 acts to simultaneously suppress steroidogenesis and stimulate proliferation remains to be fully elucidated. Thus, this study was undertaken to clarify the effects of FGF9 on the TC transcriptome. Ovaries were obtained from beef heifers at a local abattoir, TCs were isolated from large antral follicles, and cultured with or without 30 ng/mL of FGF9 for 24 h in the presence of LH and IGF-1. After treatment, total RNA was extracted from TC and processed for microarray using Affymetrix GeneChip Bovine Genome Arrays (n = 4/group). Transcriptome analysis comparing FGF9-treated TC with control TC using 1.3-fold cutoff, and a P < 0.05 significance level identified 355 differentially expressed transcripts, with 164 elements upregulated and 191 elements downregulated by FGF9. The ingenuity pathway analysis (IPA) was used to investigate how FGF9 treatment affects molecular pathways, biological functions, and the connection between molecules in bovine TC. The IPA software identified 346 pathways in response to FGF9 in TC involved in several biological functions and unveiled interesting relationships among genes related to cell proliferation (eg, CCND1, FZD5, and MYB), antioxidation/cytoprotection (eg, HMOX1 and NQO1), and steroidogenesis (eg, CYP11A1 and STAR). Overall, genes, pathways, and networks identified in this study painted a picture of how FGF9 may regulate folliculogenesis, providing novel candidate genes for further investigation of FGF9 functions in ovarian follicular development.

The impact of bisphenol S on bovine granulosa and theca cells

Bisphenol S (BPS) is an endocrine-disrupting chemical with multiple potential mechanisms of action, including as an oestrogen receptor agonist. BPS is increasingly used in plastics and thermal receipts as a substitute for bisphenol A, which has been phased out due to concerns about human health implications. The ability of BPS to alter female reproductive function in mammals has not been widely studied, despite the importance of normal hormone signalling for female reproduction. The aim of this study was to investigate how BPS (in a wide range of doses, including very low doses) affects granulosa cell and theca cell steroid hormone production and cell viability in the bovine. Granulosa cell oestradiol production was stimulated when cells were exposed to 100 μM BPS under basal conditions, but there was no effect of BPS when cells were stimulated with follicle-stimulating hormone (FSH). Additionally, there was no effect of BPS on granulosa cell progesterone production or cell viability under basal or FSH-stimulated conditions. BPS did not affect theca cell androstenedione or progesterone production, or theca cell viability under basal or luteinizing hormone-stimulated conditions. This study suggests for the first time that BPS may alter oestradiol production by bovine granulosa cells, albeit at a concentration that is unlikely to be physiologically relevant. Further studies are needed to determine the effects of BPS on the bovine oocyte and on other functions of follicular cells.

Evidence that gene expression of ovarian follicular tight junction proteins is regulated in vivo and in vitro in cattle

Tight junctions (TJ) are common paracellular sealing structures that control the transport of water, ions, and macromolecules across cell layers. Because the role of TJ in bovine follicular development is unknown, we investigated the developmental and hormonal regulation of the transmembrane TJ protein, occludin (OCLN), and the cytoplasmic TJ proteins, TJ protein 1 (TJP1) and cingulin (CGN) in bovine granulosa cells (GC) and theca cells (TC). For this purpose, bovine GC and TC were isolated from large (>8 mm) and/or small (1 to 5 mm) follicles and either extracted for real-time PCR (qPCR) or cultured in vitro. The abundances of both and mRNA were greater ( < 0.05) in TC than GC, whereas the mRNA abundance was greater ( < 0.05) in GC than TC. The abundance of mRNA in both GC and TC was greater ( < 0.05) in small follicles compared with large follicles, whereas the GC of large follicles had less ( < 0.05) mRNA abundance than the GC of small follicles. The abundance of mRNA in GC or TC did not differ ( > 0.10) among follicle sizes. In vitro treatment with various growth factors known to affect ovarian folliculogenesis indicated that , , and were hormonally regulated. Fibroblast growth factor 9 (FGF9) decreased ( < 0.05) the and mRNA abundances. Tumor necrosis factor α (TNFα) and vascular endothelial growth factor A (VEGFA) increased ( < 0.05) the mRNA abundance but decreased ( < 0.05) the mRNA abundance. Dexamethasone (DEX) increased ( < 0.05) and mRNA abundances. Epidermal growth factor (EGF) decreased ( < 0.05) and dihydrotestosterone (DHT) increased ( < 0.05) the abundances of , , and mRNA. We propose that the downregulation of OCLN and other TJ proteins during follicular development could reduce barrier function, thereby participating in increasing follicle size by allowing for an increase in the volume of follicular fluid as well as by allowing additional serum factors into the follicular fluid that potentially may directly impact GC functions. The results of the current study indicate the following in cattle: 1) gene expression of TJ proteins (i.e., , , and ) differs between GC and TC and changes with follicle size, and 2) autocrine, paracrine, and endocrine regulators, such as FGF9, EGF, DHT, TNFα, and glucocorticoids, modulate , , and mRNA abundance in TC in vitro.

Rhythmic expression of circadian clock genes in the preovulatory ovarian follicles of the laying hen

The circadian clock is reported to play a role in the ovaries in a variety of vertebrate species, including the domestic hen. However, the ovary is an organ that changes daily, and the laying hen maintains a strict follicular hierarchy. The aim of this study was to examine the spatial-temporal expression of several known canonical clock genes in the granulosa and theca layers of six hierarchy follicles. We demonstrated that the granulosa cells (GCs) of the F1-F3 follicles harbored intrinsic oscillatory mechanisms in vivo. In addition, cultured granulosa cells (GCs) from F1 follicles exposed to luteinizing hormone (LH) synchronization displayed Per2 mRNA oscillations, whereas, the less mature GCs (F5 plus F6) displayed no circadian change in Per2 mRNA levels. Cultures containing follicle-stimulating hormone (FSH) combined with LH expressed levels of Per2 mRNA that were 2.5-fold higher than those in cultures with LH or FSH alone. These results show that there is spatial specificity in the localization of clock cells in hen preovulatory follicles. In addition, our results support the hypothesis that gonadotropins provide a cue for the development of the functional cellular clock in immature GCs.

Evidence for direct effects of glyphosate on ovarian function: glyphosate influences steroidogenesis and proliferation of bovine granulosa but not theca cells in vitro

Glyphosate (GLY) is a common herbicide used worldwide but its effect on ovarian function in mammals is unknown. The aim of this study was to determine the potential endocrine disruptor effects of GLY on ovarian function evaluating cell proliferation, steroidogenesis and gene expression using bovine granulosa cells (GC) and theca cells as in vitro models. GC proliferation was impaired (P < 0.05) after exposure to GLY at 0.5, 1.7 and 5 μg ml-1 . GC progesterone production was not affected (P ≥ 0.05) at all doses tested while estradiol production was inhibited (P < 0.05) by GLY at 5 μg ml-1 . At the same concentration GLY showed no effect (P ≥ 0.05) on theca cell proliferation and steroidogenesis. At higher concentrations (0.01 and 0.3 mg ml-1 ), GLY had no significant effect (P ≥ 0.05) on GC proliferation and steroidogenesis. These studies, for the first time, suggest that GLY may affect the reproductive system in cattle via direct action on ovarian function; however, further studies will be required to understand better the mechanism of action and to determine the in vivo reproductive effects of GLY. Copyright © 2016 John Wiley & Sons, Ltd.

Transcription of CYP19A1 is directly regulated by SF-1 in the theca cells of ovary follicles in chicken

Many studies have suggested the important role of estrogen in ovarian differentiation and development of vertebrates including chicken. Cytochrome P450 aromatase, encoded by CYP19A1, is a key enzyme in estrogen synthesis, but the mechanism of CYP19A1 regulation in chicken remains unknown. Here, we found that CYP19A1 was only expressed in the theca cell layers of chicken ovary follicles. Steroidogenic factor 1 (SF-1, also named as nuclear receptor subfamily 5 group A member 1, NR5A1), a potential regulators, was expressed in both the theca cell layers and granulosa cell layers. Forkheadbox L2 (FOXL2), another potential regulator, was only expressed in the granulosa cell layers. Using luciferase assays in vitro, we found that SF-1 could activate the promoter of CYP19A1 by binding to the nuclear receptor half-site (5'-TCAAGGTCA-3') from -280 to -271 base pairs. FOXL2 did not activate the promoter of chicken CYP19A1 gene in either 293T or DF-1 cells. Overexpression of SF-1 in DF-1 cells upregulated aromatase expression, but FOXL2 could not. Taken together, our results indicated that SF-1 activates CYP19A1 mRNA expression via a conserved binding site in chicken ovary, but FOXL2 may not affect the expression of CYP19A1.

Ovarian regeneration: The potential for stem cell contribution in the postnatal ovary to sustained endocrine function

The endocrine function of the ovary is dependent upon the ovarian follicle, which on a cellular basis consists of an oocyte surrounded by adjacent somatic cells responsible for generating sex steroid hormones and maintenance of hormonal stasis with the hypothalamic-pituitary axis. As females age, both fertility and the endocrine function of the ovary decline due to waning follicle numbers as well as aging-related cellular dysfunction. Although there is currently no cure for ovarian failure and endocrine disruption, recent advances in ovarian biology centered on ovarian stem cell and progenitor cell populations have brought the prospects of cell- or tissue-based therapeutic strategies closer to fruition. Herein, we review the relative contributions of ovarian stem cells to ovarian function during the reproductive lifespan, and postulate steps toward the development of ovarian stem cell-based approaches to advance fertility treatments, and also importantly to provide a physiological long-term means of endocrine support.

Selective deletion of Pten in theca-interstitial cells leads to androgen excess and ovarian dysfunction in mice

Theca cell-selective Pten mutation (tPtenMT) in mice resulted in increases in PDK1 and Akt phosphorylation, indicating an over-activation of PI3K signaling in the ovaries. These mice displayed elevated androgen levels, ovary enlargement, antral follicle accumulation, early fertility loss and increased expression of Lhcgr and genes that are crucial to androgenesis. These abnormalities were partially reversed by treatments of PI3K or Akt inhibitor. LH actions in Pten deficient theca cells were potentiated. The phosphorylation of Foxo1 was increased, while the binding of Foxo1 to forkhead response elements in the Lhcgr promoter was reduced in tPtenMT theca cells, implying a mechanism by which PI3K/Akt-induced upregulation of Lhcgr in theca cells might be mediated by reducing the inhibitory effect of Foxo1 on the Lhcgr promoter. The phenotype of tPtenMT females is reminiscent of human PCOS and suggests that dysregulated PI3K cascade in theca cells may be involved in certain types of PCOS pathogenesis.