Steroidogenic factor-1 is required for TGF-beta3-mediated 17beta-estradiol synthesis in mouse ovarian granulosa cells

Proteomic analysis for busulfan-induced spermatogenesis disorder

BACKGROUND

Busulfan is the most commonly used drug for the treatment of chronic myelogenous leukemia and pretreatment for hematopoietic stem cell transplantation, which can damage the reproductive and immune system. However, little is known about the protein expression profiling in busulfan treated testis.

METHODS

This research studies the proteomics for busulfan-induced spermatogenesis disorder. The model of busulfan-induced mouse spermatogenesis disorder was subjected to label-free quantification proteomics analysis. Clustering heatmap, gene ontology, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and protein interaction analyses were performed and validated by molecular experiments.

RESULTS

The busulfan-treated mouse model showed abnormal testis morphology and reduced sperm number and testis weight. Testicular and sperm damage was most severe at 30 days after busulfan treatment. The busulfan-treated mouse testes were subjected to label-free quantification proteomics, which revealed 190 significantly downregulated proteins including lactate dehydrogenase A like 6B (LDHAL6B) and ubiquitin-specific protease 7 (USP7). In addition, the testis and spermatozoa in the epididymis progressively improved from 70 to 80 days after busulfan treatment, and that the testis weight and spermatozoa number gradually increased from 40 to 80 days after busulfan treatment. Western blotting revealed that LDHAL6B protein significantly increased at 10 days, decreased from 20 to 60 days, and then gradually elevated from 70 to 80 days after busulfan treatment.

CONCLUSION

We revealed 190 significantly downregulated proteins in busulfan-treated mouse testes at 30 days and indicated that 70 days is the cut-off point of spermatogenic recovery for busulfan-treated mouse testis, increasing our understanding of this reproductive disorder model. An increased understanding of busulfan's toxic effect will help to prevent and treat reproductive diseases.

A possible association between low MBL/lectin pathway functionality and microbiota dysbiosis in endometriosis patients

AIMS

Endometriosis (EM) is a chronic inflammatory disorder with multifactorial etiologies (i.e., genetics and environmental factors, hormonal and immunological changes, and microbiome alterations). The complement system is one of the most frequently dysregulated pathways in EM. Mannose-binding lectin (MBL), a carbohydrate pattern recognition molecule, is the first described recognition subcomponent of the complement lectin pathway (LP). Here, we unveiled the interplay among MBL polymorphisms, plasma levels, LP functionality, and microbiota as potential contributors to EM pathogenesis.

MATERIALS AND METHODS

A cohort of 38 EM patients and 20 healthy controls was enrolled, and the levels and functionality of the LP were assessed via ELISA. MBL genetic variants and the endometrial and vaginal microbiome were investigated and correlated.

KEY FINDINGS

High MBL levels were related to the disease severity, although not accountable for the MBL2 genotype. MBL and MASP-2 were present in the uterine mucosa but appeared to have no activity at the endometriotic lesion. EM patients with LP functional deficit displayed pathogenic bacterial species more frequently in the endometrial microbiome. Moreover, women affected by EM showed a higher frequency of rare gene variants in the estrogen pathway genes, potentially affecting MBL plasma levels.

SIGNIFICANCE

A lower functionality of LP in the uterine mucosa may contribute to an unbalanced bacterial environment that could activate endometrial cells. Not only the genotype and the inflammatory condition, but also the estrogen pathway can cause altered MBL levels, thus contributing to changes in the LP functionality.

Treatment of Qin Gui Wan (QGW) in PCOS abnormal oocytes development via AMPK/PGC-1ɑ pathway

OBJECTIVES

To investigate the therapeutic effects of Qin Gui Wan (QGW) and its disassembled functional drug groups, Wenyang Zhuhuo (WYZH) and Xinwen Zhuyang (XWZY), on letrozole-induced PCOS rats.

METHODS

PCOS rat model was established by administering letrozole for 21 days. The rats were divided into control, PCOS, Diane-35, QGW, WYZH and XWZY groups. The changes of body weight, ovarian coefficient, estrous cycle and sex hormone levels were observed. The ovarian histological characteristics and ovulation were observed by HE staining. P450arom, SF-1, and AMPK/PGC-1ɑ pathway mRNA and protein expression were analyzed using qRT-PCR, WB, and IHC. The AMPK inhibitor Compound C (CC) was used to explore the treatment mechanism of QGW in granulosa cells. And UHPLC-MS/MS was used to performed chemical composition analysis.

RESULTS

QGW, WYZH, and XWZY can correct the disordered estrous cycle of PCOS rats and improve the serum hormone status of rats to varying degrees. HE results indicated that QGW, WYZH, and XWZY improved ovarian polycystic changes and normalized ovulation. qRT-PCR, WB, and IHC results demonstrated that QGW, WYZH, and XWZY increased PGC-1α, SF-1, and P450arom mRNA and protein expression in the ovaries of PCOS rats. The level of AMPK mRNA in the ovaries of QGW and its disassembled prescriptions increased, while only WYZH and XWZY rats showed increased ovarian AMPK levels. CC attenuated the activation of AMPK, PGC-1α, SF-1, and P450arom mRNA by QGW.

CONCLUSIONS

This study demonstrates that QGW alleviates abnormal oocyte development in PCOS rats, possibly by enhancing P450arom expression via the AMPK/PGC-1α pathway, thus restoring normal androgen-estrogen balance and follicular development.

The Presence of TGFβ3 in Human Ovarian Intrafollicular Fluid and Its Involvement in Thromboxane Generation in Follicular Granulosa Cells through a Canonical TGFβRI, Smad2/3 Signaling Pathway and COX-2 Induction

Ovarian follicular fluid (FF) has a direct impact on oocyte quality, playing key roles in fertilization, implantation, and early embryo development. In our recent study, we found FF thromboxane (TX) to be a novel factor inversely correlated with oocyte maturation and identified thrombin, transforming growth factor β (TGFβ), TNF-α, and follicular granulosa cells (GCs) as possible contributors to FF TX production. Therefore, this study sought to investigate the role of TGFβ3 in regulating TX generation in human ovarian follicular GCs. TGFβ3 was differentially and significantly present in the FF of large and small follicles obtained from IVF patients with average concentrations of 68.58 ± 12.38 and 112.55 ± 14.82 pg/mL, respectively, and its levels were correlated with oocyte maturity. In an in vitro study, TGFβ3 induced TX generation/secretion and the converting enzyme-COX-2 protein/mRNA expression both in human HO23 and primary cultured ovarian follicular GCs. While TGFβRI and Smad2/3 signaling was mainly required for COX-2 induction, ERK1/2 appeared to regulate TX secretion. The participation of Smad2/3 and COX-2 in TGFβ3-induced TX generation/secretion could be further supported by the observations that Smad2/3 phosphorylation and nuclear translocation and siRNA knockdown of COX-2 expression compromised TX secretion in GCs challenged with TGFβ3. Taken together, the results presented here first demonstrated that FF TGFβ3 levels differ significantly in IVF patients' large preovulatory and small mid-antral follicles and are positively associated with oocyte maturation. TGFβ3 can provoke TX generation by induction of COX-2 mRNA/protein via a TGFβR-related canonical Smad2/3 signaling pathway, and TX secretion possibly by ERK1/2. These imply that TGFβ3 is one of the inducers for yielding FF TX in vivo, which may play a role in folliculogenesis and oocyte maturation.

Treatment of polycystic ovary syndrome and its associated psychiatric symptoms with the Mongolian medicine Nuangong Qiwei Pill and macelignan

ETHNOPHARMACOLOGICAL RELEVANCE

The Mongolian medicine Nuangong Qiwei Pill (NGQW) is a folk prescription with a long history of use by the Mongolian people. NGQW comprises seven Mongolian medicines, which have the effects of regulating and nourishing blood, warming the uterus, dispelling cold and relieving pain. For a long time, it has been used as a good remedy for gynecological diseases, with remarkable curative effects, favored by the majority of patients and recommended by doctors. Polycystic ovary syndrome (PCOS) is a common gynecological endocrine disorder that can lead to menstrual disorders or infertility. In the gynecological classification of Mongolian medicine, polycystic ovary syndrome has not been distinguished in detail, and the mechanism of NGQW in the treatment of polycystic ovary syndrome has not been scientifically studied and standardized.

AIM OF THE STUDY

The aim of this study was to clarify the mechanism of action of NGQW and macelignan in the treatment of PCOS and to provide a reference for the clinical application of these drugs.

MATERIALS AND METHODS

The effect of intragastric administration of NGQW and macelignan on PCOS model mice was observed. The mental status of mice was examined behaviorally, and serum hormone levels and oxidative stress parameters were measured by ELISA. Giemsa staining was used to detect the reproductive cycle, and HE staining was used to observe the ovarian status. Immunofluorescence staining was performed to observe the proliferation and apoptosis of ovarian granulosa cells. qRT‒PCR was conducted to measure the expression of IL-6, BAX, BCL-2, and estrogen synthesis-related genes in ovarian tissue and particle cells.

RESULTS

In the dehydroepiandrosterone (DHEA)-induced PCOS model mice, both NGQW and macelignan improved the estrous cycle; increased the estradiol (E2) content; lowered testosterone (T), progesterone (P) and luteinizing hormone (LH) levels; reduced the number of polycystic follicles; promoted granulosa cell proliferation; reduced granulosa cell apoptosis; and alleviated depression and anxiety. In addition, Nuangong Qiwei Pill and macelignan reduced the mRNA levels of the ovarian inflammatory factor IL-6; improved the disordered levels of the antioxidant indicators GSH, MDA, and SOD; and activated the TGF-β3 signaling pathway to increase the transcription of Cyp19a1, which increases estrogen secretion.

CONCLUSION

NGQW and macelignan can treat PCOS through the TGF-β3/Smad/Cyp19a1 signaling pathway to regulate the secretion ability of ovarian granulosa cells. Our research justifies the traditional use of NGQW to treat PCOS and enriches the scope of action of macelignan.

Arsenic exposure diminishes ovarian follicular reserve and induces abnormal steroidogenesis by DNA methylation

Arsenic contamination is a worldwide public health problem, and the effect of arsenic on male reproduction has been extensively studied; however, data on the biotoxicity of arsenic in terms of female reproduction are more scarce. In this study, a human-cell-animal translational strategy was applied to explore the effect of arsenic exposure on ovarian steroidogenesis and its potential mechanism. We conducted a 1:1 propensity score matched case-control study involving 127 diminished ovarian reserve (DOR) cases and 127 healthy controls. The ovarian follicular fluid levels of 21 metal elements, including arsenic, were measured. The results showed that there were significant differences in follicular fluid metal profiles between DOR patients and controls and that arsenic, molybdenum, and strontium played important roles in DOR progression [OR (95 % CI): 2.203 (1.385, 3.503), 2.308 (1.490, 3.575) and 2.922 (1.864, 4.580), respectively]. In the primary ovarian granulosa cell culture model, we found that treatment with 8 μM arsenic for 24 and 48 h induced a decrease in human granulosa cell viability. The estradiol (E₂) level was significantly decreased after arsenic exposure (P < 0.05), which was dependent on significant alterations (P < 0.05) in key enzymes in steroidogenesis. In addition, a model for sodium arsenite exposure through water in rats from weaning to sexual maturity was established. We evaluated ovarian development by monitoring the estrous cycle, observing ovarian pathology, and calculating the follicular proportion. RT-qPCR, Western blotting, and bisulfite-sequencing PCR were used to investigate the effect of arsenic exposure on ovarian steroidogenesis and its possible mechanism. The results indicated that steroidogenic factor-1 (SF-1) was an important target of the steroidogenesis disorder induced by arsenic exposure. Arsenic significantly increased the DNA methylation level (P < 0.05) in the promoter region of SF-1 to reduce its expression, subsequently decreasing the levels of steroidogenic acute regulatory protein (StAR), P450 cholesterol side-chain cleavage enzyme (CYP11A1), and aromatase (CYP19A1) (P < 0.05), leading to premature depletion of ovarian follicles.

Copper exposure disrupts ovarian steroidogenesis in human ovarian granulosa cells via the FSHR/CYP19A1 pathway and alters methylation patterns on the SF-1 gene promoter

Information on the effects of copper on reproduction is limited. Our previous study indicated that copper induces abnormal steroidogenesis in human ovarian granulosa cells, but the underlying mechanism remains unclear. In this study, human ovarian granulosa cells were treated with multiple concentrations of copper for 24 h. After treatment, the 17-estradiol levels were significantly increased (29.83 % and 45.12 %, respectively) in the 1.0 and 2.0 μg/mL groups but decreased (23.06 % and 31.56 %, respectively) in the 20.0 and 40.0 μg/mL groups (P < 0.05). Similar changes in the levels of FSHR, StAR, CYP11A1, CYP19A1, HSD3β1, and SF-1 were observed. The protein levels of FSHR were increased in the 2.0 μg/mL group but decreased in the 20.0 and 40.0 μg/mL groups (P < 0.05). Moreover, copper partially reversed the FSH-induced increase in FSHR, CYP19A1 and 17-estradiol levels, and the decreased effect of the FSH receptor binding inhibitor fragment on FSHR, CYP19A1, and 17-estradiol became more apparent after adding copper. Additionally, the total methylation levels of the SF-1 promoter and DNMTs expression were significantly decreased following copper treatment. Overall, our results indicate that copper exposure induces steroidogenesis disorders via the FSHR/CYP19A1 pathway and changes DNA methylation on the SF-1 promoter in human ovarian granulosa cells.

TGF-β1 stimulates aromatase expression and estradiol production through SMAD2 and ERK1/2 signaling pathways in human granulosa-lutein cells

Estradiol (E2), one of the main steroid hormones secreted by the ovaries, plays an important role in maintaining normal female reproductive function. Ovarian granulosa cells are the main source of E2 production because these cells express aromatase, which is encoded by the CYP19A1 gene and catalyzes the final step in E2 biosynthesis from androgens. Transforming growth factor-beta 1 (TGF-β1) and its receptors are expressed in human granulosa cells, and TGF-β1 expression can be detected in human follicular fluid. To date, TGF-β1 has been shown to regulate various ovarian functions. However, whether aromatase can be regulated by TGF-β1 in human granulosa cells has not been determined. In the present study, we demonstrate that TGF-β1 stimulates aromatase expression in primary human granulosa-lutein cells and in the human ovarian granulose-like tumor cell line, KGN. We used pharmacological inhibitors and small interfering RNA-mediated knockdown approaches to reveal that the SMAD2 and ERK1/2 signaling pathways are involved in TGF-β1-induced aromatase expression and E2 production. These results not only provide important insights into the molecular mechanisms that mediate TGF-β1-induced aromatase expression and E2 production in human granulosa cells but also increase the understanding of the normal physiological roles of TGF-β1 in the ovary.

Pharmacogenomics of aromatase inhibitors in postmenopausal breast cancer and additional mechanisms of anastrozole action

Aromatase inhibitors (AIs) reduce breast cancer recurrence and prolong survival, but up to 30% of patients exhibit recurrence. Using a genome-wide association study of patients entered on MA.27, a phase III randomized trial of anastrozole versus exemestane, we identified a single nucleotide polymorphism (SNP) in CUB And Sushi multiple domains 1 (CSMD1) associated with breast cancer–free interval, with the variant allele associated with fewer distant recurrences. Mechanistically, CSMD1 regulates CYP19 expression in an SNP- and drug-dependent fashion, and this regulation is different among 3 AIs: anastrozole, exemestane, and letrozole. Overexpression of CSMD1 sensitized AI-resistant cells to anastrozole but not to the other 2 AIs. The SNP in CSMD1 that was associated with increased CSMD1 and CYP19 expression levels increased anastrozole sensitivity, but not letrozole or exemestane sensitivity. Anastrozole degrades estrogen receptor α (ERα), especially in the presence of estradiol (E2). ER⁺ breast cancer organoids and AI- or fulvestrant-resistant breast cancer cells were more sensitive to anastrozole plus E2 than to AI alone. Our findings suggest that the CSMD1 SNP might help to predict AI response, and anastrozole plus E2 serves as a potential new therapeutic strategy for patients with AI- or fulvestrant-resistant breast cancers.

A germline variation within the CSMD1 gene predicts aromatase inhibitor response in breast cancer.

BMP-6 and SMAD4 gene expression is altered in cumulus cells from women with endometriosis-associated infertility

INTRODUCTION

Oocyte competence and quality depend on communication between the oocyte and the cumulus and theca cells. In the preantral phase, the members of the transforming growth factor β (TGF-β) superfamily are responsible for this communication and play an important role in folliculogenesis. Members of the TGF-β superfamily are related to endometriosis (overexpression in the ectopic endometrium); however, few studies have explored these proteins as influencing fertility in endometriosis. Considering endometriosis-related infertility and to better understand the role of the TGF-β superfamily members in the antral phase in women with endometriosis, this research investigated the gene expression of the genes for ligands AMH, BMP-6, GDF-9, INHA, INHBB, and TGFβ3; receptors AMHR2, BMPR2, and TGFβR3; and intracellular signalling: SMAD3 and SMAD4.

MATERIAL AND METHODS

The gene expression of AMH, BMP-6, GDF-9, INHA, INHBB, TGFβ3, AMHR2, BMPR2, TGFβR3, SMAD3, and SMAD4 in cumulus cells was investigated through quantitative real-time PCR in a case-control study including infertile women with and without peritoneal endometriosis undergoing in vitro fertilization.

RESULTS

Age and outcomes of assisted reproduction were similar between the groups (P > .05). However, women with endometriosis showed reduced expression of BMP-6 and SMAD4 (P < .05) in cumulus cells compared with the control group, other genes did not present altered gene expression in women with endometriosis (P > .05).

CONCLUSIONS

The reduced expression of BMP-6 and SMAD4 in women with peritoneal endometriosis compared with the control group indicates that granulosa (cumulus) cell function could be altered in these women.

LncRNA-Gm2044 is transcriptionally activated by A-MYB and regulates Sycp1 expression as a miR-335-3p sponge in mouse spermatocyte-derived GC-2spd(ts) cells

Long noncoding RNAs (lncRNAs) have been shown to execute key roles in spermatogenesis. However, little is known about how lncRNAs gene expression is itself regulated in the germ cells of testis. We previously demonstrated that high expression of lncRNA-Gm2044 exists in spermatocytes and can regulate male germ cell proliferation. Here, the transcriptional regulation of lnRNA-Gm2044 expression in spermatocytes and the downstream signaling were further explored. A bioinformatics assessment predicted two potential binding-sites for the spermatocyte-specific transcription factor A-MYB in the promoter region of lncRNA-Gm2044. Our results proved that the transcription factor A-MYB promotes the expression of lncRNA-Gm2044 in mouse spermatocyte-derived GC-2spd(ts) cells. ChIP and luciferase assays verified that A-MYB mainly binds to the distal promoter region (-819 bp relative to the transcription start site) of lncRNA-Gm2044 and regulates lncRNA-Gm2044 expression through the -819 bp binding-site. In addition, we confirmed that lncRNA-Gm2044 functions as a miR-335-3p sponge to enhance the levels of miR-335-3p's direct target protein, Sycp1. Furthermore, A-MYB can up-regulate Sycp1 expression and down-regulate GC-2spd(ts) cell proliferation by activating its target, lncRNA-Gm2044. Overexpression of lncRNA-Gm2044 or knockdown of miR-335-3p can, at least partially, rescue the effects of A-MYB on Sycp1 expression and GC-2spd(ts) cell proliferation.Taken together, our results provide new information on the mechanistic roles of lncRNA-miRNA in transcription factor A-MYB regulation of spermatocyte function.

Transactivation of miR-202-5p by Steroidogenic Factor 1 (SF1) Induces Apoptosis in Goat Granulosa Cells by Targeting TGFβR2

MicroRNAs play key roles during ovary development, with emerging evidence suggesting that miR-202-5p is specifically expressed in female animal gonads. Granulosa cells (GCs) are somatic cells that are closely related to the development of female gametes in mammalian ovaries. However, the biological roles of miR-202-5p in GCs remain unknown. Here, we show that miR-202-5p is specifically expressed in GCs and accumulates in extracellular vesicles (EVs) from large growth follicles in goat ovaries. In vitro assays showed that miR-202-5p induced apoptosis and suppressed the proliferation of goat GCs. We further revealed that miR-202-5p is a functional miRNA that targets the transforming growth factor-beta type II receptor (TGFβR2). MiR-202-5p attenuated TGF-β/SMAD signaling through the degradation of TGFβR2 at both the mRNA and protein level, decreasing p-SMAD3 levels in GCs. Moreover, we verified that steroidogenic factor 1 (SF1) is a transcriptional factor that binds to the promoters of miR-202 and cytochrome P450 family 19 subfamily A member 1 (CYP19A1) through luciferase reporter and chromatin immunoprecipitation (ChIP) assays. That contributed to positive correlation between miR-202-5p and CYP19A1 expression and estradiol (E2) release. Furthermore, SF1 repressed TGFβR2 and p-SMAD3 levels in GCs through the transactivation of miR-202-5p. Taken together, these results suggest a mechanism by which miR-202-5p regulates canonical TGF-β/SMAD signaling through targeting TGFβR2 in GCs. This provides insight into the transcriptional regulation of miR-202 and CYP19A1 during goat ovarian follicular development.

Novel Sex Chromosomes in 3 Cichlid Fishes from Lake Tanganyika

African cichlids are well known for their adaptive radiations, but it is now apparent that they also harbor an extraordinary diversity of sex chromosome systems. In this study, we sequenced pools of males and females from species in 3 different genera of cichlids from Lake Tanganyika. We then searched for regions that were differentiated following the patterns expected for sex chromosomes. We report 2 novel sex chromosomes systems, an XY system on LG19 in Tropheus sp. "black" and a ZW system on LG7 in Hemibates stenosoma. We also identify a ZW system on LG5 in Cyprichromis leptosoma that may be convergent with a system previously described in Lake Malawi cichlids. Our data also identify candidate single nucleotide polymorphisms for the blue/yellow tail color polymorphism observed among male C. leptosoma.

LncRNA Gm2044 promotes 17β-estradiol synthesis in mpGCs by acting as miR-138-5p sponge

Long noncoding RNAs (lncRNAs) have been demonstrated to play vital roles in mammalian reproduction. Our previous research revealed that lncRNA Gm2044 is highly expressed in mouse spermatocytes and regulates male germ cell function. The gene annotation database BioGPS shows that Gm2044 is not only highly expressed in testicular tissue but also in ovarian tissue, which suggests that Gm2044 may be involved in female reproductive development. In this study, we confirmed that lncRNA Gm2044 promotes 17β-estradiol synthesis in mouse pre-antral follicular granulosa cells (mpGCs). Furthermore, bioinformatics methods, western blot, and the luciferase assay proved that Gm2044 functions as a miR-138-5p sponge to inhibit the direct target of miR-138-5p, Nr5a1, which enhances 17β-estradiol synthesis through cyp19a1 activation. Taken together, our results provide an insight into the mechanistic roles of lncRNA Gm2044 for 17β-estradiol synthesis by acting as competing-endogenous RNAs to modulate the function of mpGCs. Studying the potential lncRNAs, which regulate estradiol release, will be beneficial for the diagnosis and treatment of steroid hormone-related disease.

Tanshinone IIA attenuates estradiol-induced polycystic ovarian syndrome in mice by ameliorating FSHR expression in the ovary

Tanshinone IIA (TSIIA) is a major component of Salvia miltiorrhiza, a Chinese herb that exhibits a therapeutic effect on polycystic ovary syndrome (PCOS). The present study replicated PCOS via the neonatal treatment of estradiol in mice. Estrous cycles, body and ovarian weight, serum levels of testosterone and estradiol were determined. Histological examination of ovaries was performed. The mRNA and protein levels of aromatase luteinizing hormone receptor and follicle-stimulating hormone (FSHR) in ovaries and granule cells were assayed by reverse transcription-quantitative polymerase chain reaction and western blotting, respectively. TSIIA was revealed to reverse all disorders induced by estradiol treatment, including prolonged estrous cycles, increased body and ovarian weight, increased atretic cyst-like follicles and decreased corpus luteum, large antral follicles and preovulatory follicles. These improvements in PCOS as a result of TSIIA treatment are likely due to the revised testosterone/estradiol balance, as TSIIA reversed the decrease in aromatase mRNA, the enzyme that converts androgen to estrogen. As the expression of aromatase is regulated by the FSH pathway, TSIIA-mediated elevation in FSHR expression may lead to the upregulation of aromatase. Therefore, TSIIA revises the balance of androgen and estrogen by rescuing the reduced expression of FSHR and aromatase, thus attenuating murine PCOS. The current study aimed to further the application of natural drugs in the treatment of PCOS to confront the side effects of hormone drugs and expand the use of TSIIA.

The Orphan Nuclear Receptors Steroidogenic Factor-1 and Liver Receptor Homolog-1: Structure, Regulation, and Essential Roles in Mammalian Reproduction

Nuclear receptors are intracellular proteins that act as transcription factors. Proteins with classic nuclear receptor domain structure lacking identified signaling ligands are designated orphan nuclear receptors. Two of these, steroidogenic factor-1 (NR5A1, also known as SF-1) and liver receptor homolog-1 (NR5A2, also known as LRH-1), bind to the same DNA sequences, with different and nonoverlapping effects on targets. Endogenous regulation of both is achieved predominantly by cofactor interactions. SF-1 is expressed primarily in steroidogenic tissues, LRH-1 in tissues of endodermal origin and the gonads. Both receptors modulate cholesterol homeostasis, steroidogenesis, tissue-specific cell proliferation, and stem cell pluripotency. LRH-1 is essential for development beyond gastrulation and SF-1 for genesis of the adrenal, sexual differentiation, and Leydig cell function. Ovary-specific depletion of SF-1 disrupts follicle development, while LRH-1 depletion prevents ovulation, cumulus expansion, and luteinization. Uterine depletion of LRH-1 compromises decidualization and pregnancy. In humans, SF-1 is present in endometriotic tissue, where it regulates estrogen synthesis. SF-1 is underexpressed in ovarian cancer cells and overexpressed in Leydig cell tumors. In breast cancer cells, proliferation, migration and invasion, and chemotherapy resistance are regulated by LRH-1. In conclusion, the NR5A orphan nuclear receptors are nonredundant factors that are crucial regulators of a panoply of biological processes, across multiple reproductive tissues.

The transcription factor SMAD4 and miR-10b contribute to E2 release and cell apoptosis in ovarian granulosa cells by targeting CYP19A1

The cytochrome P450 family 19 subfamily A member 1 (CYP19A1) gene, encodes aromatase, a key enzyme in estradiol (E2) synthesis, and is down-regulated during porcine follicular atresia. However, its role in and the mechanism of transcriptional repression in follicular atresia is largely unknown. In the present study, we show that the CYP19A1 gene stimulates E2 release and inhibits cell apoptosis in porcine granulosa cells (GCs). SMAD4, an anti-apoptotic moderator, was identified as a transcription factor of the porcine CYP19A1 gene and enhanced the expression and function of CYP19A1 in porcine GCs through direct binding to a SMAD4-binding element (SBE) within the promoter region of CYP19A1 gene. Moreover, we found that miR-10b, a pro-apoptotic factor, directly interacted with 3'-UTR of the porcine CYP19A1 mRNA, inhibiting its expression and function in porcine GCs. Collectively, we demonstrated that CYP19A1 is an inhibitor of follicular atresia and is regulated by both SMAD4 and miR-10b. These findings provide further insight into the mechanisms of CYP19A1 in steroid hormone synthesis and GC apoptosis and provide molecular targets for exploring methods of treatment for steroid-dependent reproductive disorders.

Follicle-stimulating hormone (FSH) promotes retinol uptake and metabolism in the mouse ovary

BACKGROUND

Retinoids (retinol and its derivatives) are required for the development and maintenance of normal physiological functions of the ovary. However, the mechanisms underlying the regulation of ovarian retinoid homeostasis during follicular development remain unclear.

METHODS

The present study determined retinoid levels and the expression levels of genes involved in the retinol uptake and its metabolic pathway in the ovaries of follicle-stimulating hormone (FSH)-treated mice and in granulosa cells treated with FSH using ultra performance liquid chromatography (UPLC) combined with quadrupole time-of-flight high-sensitivity mass spectrometry (Q-TOF/HSMS) and real-time PCR analysis.

RESULTS

The levels of total retinoids and retinoic acid (RA) and expressions of retinol-oxidizing enzyme genes alcohol dehydrogenase 1 (Adh1) and aldehyde dehydrogenase (Aldh1a1) are increased in the ovaries of mice treated with FSH; in contrast, the retinyl ester levels and retinol-esterifying enzyme gene lecithin: retinol acyltransferase (Lrat) expression are diminished. In FSH-treated granulosa cells, the levels of retinyl esters, retinaldehyde, and total retinoids are augmented; and this is coupled with an increase in the expressions of stimulated by retinoic acid 6 (Stra6) and cellular retinol-binding protein 1 (Crbp1), genes in the retinol uptake pathway, and Adh1, Adh7, and Aldh1a1 as well as a diminution in Lrat expression.

CONCLUSIONS

These data suggest that FSH promotes retinol uptake and its conversion to RA through modulating the pathways of retinol uptake and metabolism in the mouse ovary. The present study provides a possible mechanism for the regulation of endogenous RA signaling in the developing follicles.

Mutation -388 C>G of NR5A1 gene affects litter size and promoter activity in sheep

The Nuclear receptor superfamily 5, group A, member 1 (NR5A1) gene encodes a nuclear receptor that regulates the transcription of genes involved in steroidogenesis, follicular development and female fertility. Little, however, is known about the relationship of this gene with reproductive performance in sheep. In this study, the transcription initiation site of Hu sheep NR5A1 gene was located 193 nucleotides (i.e., at -193 nt) before the translational start site (ATG). The core promoter region of the NR5A1 gene ranged from -696 nt to -298 nt, and a C>G mutation at -388 nt was detected in this region. Association analysis indicated ewes with the GG genotype had greater litter size at the second and third parity than those with the CC genotype (P < 0.05). The results from the luciferase assay provided evidence that the -388 G allele increased luciferase activity compared with that of the -388 C allele. Furthermore, the -388 C>G mutation lost a CpG site and gained a novel binding site for the transcription factor, SP1, and results from an overexpression experiment and methylation analysis indicated transcription factor SP1 and methylation of the -388 C>G mutation were both involved in alteration of NR5A1 transcription activity. Results of the present study revealed that the -388 C>G mutation lost a CpG site and promoted NR5A1 gene expression, which completely superimposed positive effects on NR5A1 gene transcription activity by transcription factor SP1, resulting in a fecundity increase in Hu sheep.

Regulation by FSH of the dynamic expression of retinol-binding protein 4 in the mouse ovary

BACKGROUND

Ovarian retinoid homeostasis plays an important role in the physiological function of the ovary. Retinol-binding protein 4 (RBP4) acts as the mediator for the systemic and intercellular transport of retinol and is heavily involved in cellular retinol influx, efflux, and exchange. However, the expression patterns and regulatory mechanisms of Rbp4 in the ovary remain unclear.

METHODS

The expression pattern of ovarian Rbp4 was examined in immature mice during different developmental stages and in adult mice during different stages of the estrous cycle. The potential regulation and mechanisms of ovarian Rbp4 expression by estrogen and related gonadotropins in mouse ovaries were also investigated.

RESULTS

The present study demonstrated that the ovarian expression of Rbp4 remained constant before puberty and increased significantly in the peripubertal period. In adult female mice, the expression of Rbp4 increased at proestrus and peaked at estrus at both the mRNA and protein levels. The protein distribution of RBP4 was mainly localized in the granulosa cell and theca cell layer in follicles. In addition, the expression of Rbp4 was significantly induced by follicle-stimulating hormone (FSH) or FSH + luteinizing hormone (LH) in combination in immature mouse (3 weeks old) ovaries in vivo and in granulosa cells cultured in vitro, both at the mRNA and protein levels. In contrast, treatment with LH or 17β-estradiol did not exhibit any observable effects on ovarian Rbp4 expression. Transcription factors high-mobility group AT-hook 1 (HMGA1), steroidogenic factor 1 (SF-1), and liver receptor homolog 1 (LRH-1) (which have been previously shown to be involved in activation of Rbp4 transcription), also responded to FSH stimulation. In addition, H-89, an inhibitor of protein kinase A (PKA), and the depletion of HMGA1, SF-1, and LRH-1 by small interfering RNAs (siRNAs), resulted in a dramatic loss of the induction of Rbp4 expression by FSH at both the mRNA and protein levels.

CONCLUSIONS

These data indicate that the dynamic expression of Rbp4 is mainly regulated by FSH through the cAMP-PKA pathway, involving transcriptional factors HMGA1, SF-1, and LRH-1, in the mouse ovary during different stages of development and the estrous cycle.

KH-type splicing regulatory protein is a new component of chromatoid body

The chromatoid body (CB) is a specific cloud-like structure in the cytoplasm of haploid spermatids. Recent findings indicate that CB is identified as a male germ cell-specific RNA storage and processing center, but its function has remained elusive for decades. In somatic cells, KH-type splicing regulatory protein (KSRP) is involved in regulating gene expression and maturation of select microRNAs (miRNAs). However, the function of KSRP in spermatogenesis remains unclear. In this study, we showed that KSRP partly localizes in CB, as a component of CB. KSRP interacts with proteins (mouse VASA homolog (MVH), polyadenylate-binding protein 1 (PABP1) and polyadenylate-binding protein 2 (PABP2)), mRNAs (Tnp2 and Odf1) and microRNAs (microRNA-182) in mouse CB. Moreover, KSRP may regulate the integrity of CB via DDX5-miRNA-182 pathway. In addition, we found abnormal expressions of CB component in testes of Ksrp-knockout mice and of patients with hypospermatogenesis. Thus, our results provide mechanistic insight into the role of KSRP in spermatogenesis.

STMN1 Promotes Progesterone Production Via StAR Up-regulation in Mouse Granulosa Cells

Stathmin 1 (STMN1) is a biomarker in several types of neoplasms. It plays an important role in cell cycle progression, mitosis, signal transduction and cell migration. In ovaries, STMN1 is predominantly expressed in granulosa cells (GCs). However, little is known about the role of STMN1 in ovary. In this study, we demonstrated that STMN1 is overexpressed in GCs in patients with polycystic ovary syndrome (PCOS). In mouse primary GCs, the overexpression of STMN1 stimulated progesterone production, whereas knockdown of STMN1 decreased progesterone production. We also found that STMN1 positively regulates the expression of Star (steroidogenic acute regulatory protein) and Cyp11a1 (cytochrome P450 family 11 subfamily A member 1). Promoter and ChIP assays indicated that STMN1 increased the transcriptional activity of Star and Cyp11a1 by binding to their promoter regions. The data suggest that STMN1 mediates the progesterone production by modulating the promoter activity of Star and Cyp11a1. Together, our findings provide novel insights into the molecular mechanisms of STMN1 in ovary GC steroidogenesis. A better understanding of this potential interaction between STMN1 and Star in progesterone biosynthesis in GCs will facilitate the discovery of new therapeutic targets in PCOS.

Zeranol stimulates proliferation and aromatase activation in human breast preadipocytes

Aromatase is a crucial enzyme for the biosynthesis of estrogens and is involved in the process of breast carcinogenesis. Concerns have been raised regarding the effects of environmental estrogens as potential regulators of aromatase expression in human breast cells. Zeranol is a non‑steroidal agent with potent estrogenic activity, which is widely used as a growth promoter for cattle in certain countries. The present study hypothesized that aromatase expression and activity may be elevated by low dose zeranol exposure, providing a source of estrogens that may stimulate cell proliferation. In the present study, primary cultured human breast preadipocytes were used as an in vitro model. The effects of zeranol on cell proliferation were measured using the MTS assay, aromatase expression levels were determined by immunocytochemical staining and reverse transcription‑polymerase chain reaction, and aromatase enzyme activity and estrogen production were analyzed using corresponding assay kits. The results demonstrated that low dose zeranol (2‑50 nM) was able to significantly promote cell proliferation, aromatase mRNA expression, aromatase activity and estrogen production in primary cultured human breast preadipocytes, thus suggesting that zeranol may act as an aromatase activator. The findings of the present study suggest that zeranol promotes breast cancer cell growth by stimulating aromatase activation and increasing estrogen biosynthesis in adipose tissue.

MicroRNA-764-3p regulates 17β-estradiol synthesis of mouse ovarian granulosa cells by targeting steroidogenic factor-1

Previous studies have reported that microRNA-764-3p (miR-764-3p) is one of the most up-regulated microRNAs (miRNAs) in TGF-β1-stimulated mouse ovarian granulosa cells. However, little is known about the roles and mechanisms of miR-764-3p in granulosa cell function during follicular development. In this study, we found that overexpression of miR-764-3p inhibited 17β-estradiol (E2) synthesis of granulosa cells through directly targeting steroidogenic factor-1 (SF-1). MiR-764-3p inhibited SF-1 by affecting its messenger RNA (mRNA) stability, which subsequently suppressed the expression levels of Cyp19a1 gene (aromatase, a downstream target of SF-1). In addition, SF-1 was involved in regulation of miR-764-3p-mediated Cyp19a1 expression in granulosa cells which contributed, at least partially, to the effects of miR-764-3p on granulosa cell E2 release. These results suggest that miR-764-3p functions to decrease steroidogenesis by targeting SF-1, at least in part, through inactivation of Cyp19a1. Taken together, our data provide mechanistic insights into the roles of miR-764-3p on E2 synthesis. Understanding of potential miRNAs affecting estrogen synthesis will help to diagnose and treat steroid-related diseases.

Downregulation of miR-320a/383-sponge-like long non-coding RNA NLC1-C (narcolepsy candidate-region 1 genes) is associated with male infertility and promotes testicular embryonal carcinoma cell proliferation

Long non-coding RNAs (lncRNAs), which are extensively transcribed from the genome, have been proposed to be key regulators of diverse biological processes. However, little is known about the role of lncRNAs in regulating spermatogenesis in human males. Here, using microarray technology, we show altered expression of lncRNAs in the testes of infertile men with maturation arrest (MA) or hypospermatogenesis (Hypo), with 757 and 2370 differentially down-regulated and 475 and 163 up-regulated lncRNAs in MA and Hypo, respectively. These findings were confirmed by quantitative real-time PCR (qRT-PCR) assays on select lncRNAs, including HOTTIP, imsrna320, imsrna292 and NLC1-C (narcolepsy candidate-region 1 genes). Interestingly, NLC1-C, also known as long intergenic non-protein-coding RNA162 (LINC00162), was down-regulated in the cytoplasm and accumulated in the nucleus of spermatogonia and primary spermatocytes in the testes of infertile men with mixed patterns of MA compared with normal control. The accumulation of NLC1-C in the nucleus repressed miR-320a and miR-383 transcript and promoted testicular embryonal carcinoma cell proliferation by binding to Nucleolin. Here, we define a novel mechanism by which lncRNAs modulate miRNA expression at the transcriptional level by binding to RNA-binding proteins to regulate human spermatogenesis.

Identification of miRNAs during mouse postnatal ovarian development and superovulation

BACKGROUND

MicroRNAs are small noncoding RNAs that play critical roles in regulation of gene expression in wide array of tissues including the ovary through sequence complementarity at post-transcriptional level. Tight regulation of multitude of genes involved in ovarian development and folliculogenesis could be regulated at transcription level by these miRNAs. Therefore, tissue specific miRNAs identification is considered a key step towards understanding the role of miRNAs in biological processes.

METHODS

To investigate the role of microRNAs during ovarian development and folliculogenesis we sequenced eight different libraries using Illumina deep sequencing technology. Different developmental stages were selected to explore miRNAs expression pattern at different stages of gonadal maturation with/without treatment of PMSG/hCG for superovulation.

RESULTS

From massive sequencing reads, clean reads of 16-26 bp were selected for further analysis of differential expression analysis and novel microRNA annotation. Expression analysis of all miRNAs at different developmental stages showed that some miRNAs were present ubiquitously while others were differentially expressed at different stages. Among differentially expressed miRNAs we reported 61 miRNAs with a fold change of more than 2 at different developmental stages among all libraries. Among the up-regulated miRNAs, mmu-mir-1298 had the highest fold change with 4.025 while mmu-mir-150 was down-regulated more than 3 fold. Furthermore, we found 2659 target genes for 20 differentially expressed microRNAs using seven different target predictions programs (DIANA-mT, miRanda, miRDB, miRWalk, RNAhybrid, PICTAR5, TargetScan). Analysis of the predicted targets showed certain ovary specific genes targeted by single or multiple microRNAs. Furthermore, pathway annotation and Gene ontology showed involvement of these microRNAs in basic cellular process.

CONCLUSIONS

These results suggest the presence of different miRNAs at different stages of ovarian development and superovulation. Potential role of these microRNAs was elucidated using bioinformatics tools in regulation of different pathways, biological functions and cellular components underlying ovarian development and superovulation. These results provide a framework for extended analysis of miRNAs and their roles during ovarian development and superovulation. Furthermore, this study provides a base for characterization of individual miRNAs to discover their role in ovarian development and female fertility.

NGF promotes mouse granulosa cell proliferation by inhibiting ESR2 mediated down-regulation of CDKN1A

Nerve growth factor (NGF) is known to play key roles in ovarian follicular development, such as the assembly of early follicles and follicular ovulation through its high-affinity receptor, tyrosine kinase receptor A (trkA). Herein, the molecular mechanism controlling NGF-induced granulosa cell (GC) proliferation was not clear. In this study, we found that NGF is abundant in preantral GCs and knockdown of trkA in GCs attenuated NGF-induced GC proliferation and further decreased the levels of phosphorylated extracellular regulated protein kinases 1/2 (ERK1/2). Cyclin-dependent kinase inhibitor 1A (CDKN1A), also named p21, a factor which could be either a negative or a positive regulator via transformation related protein 53 (TRP53, also named p53)-dependent or independent pathways in cell proliferation, was up-regulated during the process of NGF-induced GC proliferation. Blockade of trkA (K252α) and ERK1/2 (U0126) in GCs decreased NGF-induced expression of CDKN1A and did not alter the expression of TRP53, indicating that NGF stimulates CDKN1A expression via the trkA-ERK1/2 pathway in a TRP53-independent manner. Meanwhile, ESR2, a tumor suppressor which is exclusively expressed in GCs, was suppressed in NGF-induced GC proliferation, and this effect was abrogated by U0126. Blockade of ESR2 (ICI182,780) caused the promotion of GC proliferation and CDKN1A expression, indicating that ESR2 may be downstream of the ERK1/2 pathway in mediating the effect of CDKN1A on NGF-induced GC proliferation. Therefore, ESR2 may be involved in the integration of intracellular signal cascades and cell cycle proteins in affecting GC proliferation. Here, we provide mechanistic insights into the roles of CDKN1A in NGF-induced GC proliferation. Understanding potential cross-points between CDKN1A and ESR2 affecting GC proliferation will help in the discovery of new therapeutic targets in some female infertility disorders.

MicroRNA-302a sensitizes testicular embryonal carcinoma cells to cisplatin-induced cell death

Cisplatin is a commonly used chemotherapeutic agent for the treatment of several human malignancies, such as testicular germ cell tumors (TGCT). The toxic effects persist and those that are present long after chemotherapy affect the overall quality of life of patients. MicroRNAs (miRNAs) play important roles in the responses of cancer cells to chemotherapy and have been shown to modulate cell sensitivity to chemotherapeutic drugs. However, the relationship between miRNA expression and cisplatin sensitivity of TGCT has not been fully explored. In this study, the effects of miR-302a on cisplatin cytotoxicity in TGCT-derived cell line NTERA-2 (NT2) were evaluated. We found that expression levels of miR-302a were increased in cisplatin-treated NT2 cells. Up-regulation of miR-302a significantly increased the sensitivity of NT2 cells to cisplatin by enhancing cisplatin-induced G2/M phase arrest and the subsequent progression to apoptosis. MiR-302a also increased the killing effects of cisplatin by lowering the apoptotic threshold; the same result was also observed in another TGCT-derived cell line, NCCIT. Furthermore, miR-302a-enhanced cisplatin sensitivity was partially mediated through the down-regulation of p21 in NT2 cells. MiR-302a induced apoptosis was further enhanced by silencing of p53 in NT2 cells. p53 levels were inversely associated with the expression of Oct4, Sox2, and Nanog in response to cisplatin. Thus, targeting miR-302a may offer new therapeutic interventions in TGCT.

Knockdown of TrkA in cumulus oocyte complexes (COCs) inhibits EGF-induced cumulus expansion by down-regulation of IL-6

Tyrosine kinase receptor A (TrkA), the high-affinity receptor of nerve growth factor (NGF), is known to play key roles in ovarian follicular development, such as assembly of early follicles and follicular ovulation. However, little is known about the roles of TrkA in cumulus oocyte complex (COC) expansion. In this study, we found that TrkA was abundant in large antral follicles and knockdown of TrkA in COCs attenuated epidermal growth factor (EGF)-induced COC expansion and further decreased the ovulation rate. The effect of TrkA on COC expansion was not mediated through downstream EGF effectors, phosphorylation of extracellular regulated protein kinases 1/2 (ERK1/2) or drosophila mothers against decapentaplegic protein (SMAD), or through up-regulation of COC expansion-related transcripts such as prostaglandin-endoperoxide synthase 2 (Ptgs2), hyaluronan synthase 2 (Has2), TNF-induced protein 6 (Tnfaip6) or pentraxin 3 (Ptx3). However, pharmacological blockade of TrkA transducing activity (K252α) in COCs decreased the mRNA expression and protein secretion of interleukin-6 (IL-6), identified from mRNA microarray of K252α-treated COCs. Meanwhile, knockdown of IL-6 attenuated EGF-induced COC expansion. In addition, IL-6 rescued the inhibitory effect of K252α on EGF-induced cumulus expansion. Therefore, IL-6 may act as a new potential cumulus expansion-related transcript, which may be involved in the integration of TrkA and EGF signaling in affecting COC expansion. Here, we provide mechanistic insights into the roles of TrkA in EGF-induced cumulus expansion. Understanding potential cross-points between TrkA and EGF affecting cumulus expansion will help in the discovery of new therapeutic targets in ovulation-related diseases.

MicroRNA-224 is involved in the regulation of mouse cumulus expansion by targeting Ptx3

MicroRNAs (miRNAs) are indicated to regulate ovarian development in a cell- or stage-specific manner. Our previous study showed that miR-224 is involved in TGF-β1-mediated follicular granulosa cell (GC) growth and estradiol (E2) production during the transition from the preantral to early antral stage by targeting Smad4. In this study, miR-224 was found to target pentraxin 3 (Ptx3), a gene critical for cumulus expansion during ovulation. In addition, PTX3 was up-regulated in mouse mural GCs and cumulus-oocyte complexes (COCs) by TGF-β1 treatment, which was partially mediated by miR-224. The effect of miR-224 during ovulation was further examined in vitro and in vivo by construction of an adenovirus-mediated expression vector for miR-224 (Ad-miR-224). In vitro studies demonstrated that miR-224 could perturb cumulus expansion in EGF-stimulated COCs by decreasing PTX3 secretion. In vivo studies also showed that injection of Ad-miR-224 into ovarian bursa decreased PTX3 expression and disrupted ovulation, which led to a decreased number of implantation sites and offspring being born. These results indicate that miR-224 may affect ovulation and subsequent embryo development by targeting Ptx3, suggesting potential roles for miRNAs in offering new treatments for ovulation disorder-associated infertility, or, conversely, designing new contraceptives.

microRNA-383 impairs phosphorylation of H2AX by targeting PNUTS and inducing cell cycle arrest in testicular embryonal carcinoma cells

Male germ cells with aberrant DNA damage are the weighted factor contributing to male infertility. Mounting evidence shows that DNA damage in male germ cells impairs spermatogenesis and lowers fecundity. MicroRNAs (miRNAs) regulating expression of multiple genes play a significant role in spermatogenesis. Our previous results have shown that microRNA-383 (miR-383) is one of the notable down-regulated microRNAs in the testes of sterile males with maturation arrest (MA) and is located predominantly in spermatogonia and primary spermatocytes. However, the role that miR-383 plays in DNA damage during spermatogenesis remains unknown. In this study, we found that miR-383 inhibited the focal formation and abundance of γH2AX, which is the major marker of sites of DNA damage, with or without ultraviolet irradiation and cisplatin in testicular embryonal carcinoma (NT-2) cells. In addition, NT-2 cells were remarkably sensitized to DNA damage reagent (cisplatin) by forcing expression of miR-383 and silencing expression of protein phosphatase 1, regulatory subunit 10 (PNUTS). By constructing Renilla luciferase reporters and co-transfecting miR-383 and reporters in NT-2 cells, we identified that PNUTS was a valid target of miR-383. Further results demonstrated that the repression of the phosphorylated form of H2AX by miR-383 was due to independent depletion of PNUTS and cell cycle arrest. In conclusion, we found a novel function of miR-383 in the DNA damage pathway. miR-383 impairs the phosphorylation of H2AX by targeting PNUTS and inducing cell cycle arrest independently, as well as sensitizing NT-2 cells to cisplatin.

Nuclear export factor 3 is involved in regulating the expression of TGF-β3 in an mRNA export activity-independent manner in mouse Sertoli cells

The NXF (nuclear export factor) family members are implicated in the transport of mRNA from the nucleus to the cytoplasm. Recently, some members of the NXF family have been reported to play divergent functional roles, such as post-transcriptional regulation, translational control, regulation of mRNA stability and trafficking. However, little is known about the roles of NXF3 in spermatogenesis. In the present study, we found that mouse NXF3, specifically expressed in principal cells in segment II of the caput epididymis, as well as Sertoli cells in the mouse testis, was required to mediate TGF-β (transforming growth factor β)-induced down-regulation of Tgfb3/TGF-β3 mRNA expression and protein secretion in Sertoli cells. In addition, NXF3 was also involved in TGF-β-induced transcriptional regulation of other genes associated with Sertoli cell maturation and the restructuring of the Sertoli cell BTB (blood-testis barrier), such as Gata1 (GATA-binding protein 1), Wt1 (Wilms's tumour homologue 1), Cldn11 (claudin11) and Cdkn1a (cyclin-dependent kinase inhibitor 1A or p21(Cip1)). The transcriptional regulation of NXF3 was mediated through physical interaction with STRAP (serine/threonine kinase receptor-associated protein), where NXF3 inhibited the complex formation among Smad7, STRAP and activated type I TGF-β receptor. Taken together, our data provide mechanistic insights into the roles of NXF3 in TGF-β-mediated expression of Tgfb3 and other genes. NXF3 may be implicated in Sertoli cell maturation and the extensive restructuring of the Sertoli cell BTB.

Transcriptional cooperation between p53 and NF-κB p65 regulates microRNA-224 transcription in mouse ovarian granulosa cells

MicroRNAs (miRNAs) have been indicated to play key roles in ovarian follicular development. However, little is known about how the miRNA gene expression itself is regulated in the mammalian ovary. We previously reported that miR-224 is involved in TGF-β1-mediated follicular granulosa cell (GC) growth and estradiol (E2) production by targeting Smad4. Here, the transcriptional regulation of miR-224 expression in GCs was further investigated. Our results showed that both the tumor suppressor gene p53 and NF-κB p65 subunit suppressed the TGF-β1-induced increase in pri-miR-224 expression in GCs. ChIP assays demonstrated that TGF-β1 enhanced the binding of p53 and p65 to the proximal promoter region of GABAA receptor ε subunit (miR-224 host gene). p53 and p65 transcriptionally cooperated to inactivate the GABAA receptor ε subunit promoter. In addition, p53/p65 could up-regulate Smad4 expression by inhibiting its target miR-224 in GCs which contributed, at least partially, to the effects of miR-224 and Smad4 on GC proliferation and E2 release. Our results provide new data about the interplay between transcription factors involved in GC proliferation and function by cooperatively regulating miRNA expression.

Selective Smad4 knockout in ovarian preovulatory follicles results in multiple defects in ovulation

The TGF-β signaling pathway is involved with multiple processes in the mammalian ovary, including primordial follicle formation, granulosa cell (GC) proliferation, follicle atresia, ovulation, and feedback regulation between the pituitary and ovary. The transcriptional factor SMAD4 (Sma- and Mad-related protein 4) is the central component of the canonical TGF-β signaling pathway. Smad4 knockout (KO) using Amhr2-Cre, which is expressed in GCs of immature developing follicles, causes premature luteinization. In this study, we specifically depleted Smad4 in GCs of preovulatory follicles using Cyp19-Cre mice. As different from results with Smad4(fl/fl);Amhr2-Cre mice, Smad4 depletion in preovulatory follicles did not cause premature luteinization or suppress GC proliferation; rather, it increased follicle atresia. In addition, Nppc and Npr2 expressions were reduced by Smad4 depletion; thus, their effect of maintaining oocyte meiotic arrest was weakened in Smad4 conditional KO mice. Smad4(fl/fl);Cyp19-Cre female mice were subfertile and had irregular estrous cycles and ovulation defects. Smad4 KO also blocked LH-induced cumulus expansion and follicle rupture, but not oocyte meiotic resumption. Our results also indicated that SMAD4 was required for LH-stimulated activation of ERK1/2 and the expressions of ovulation-related genes. The defects arising from SMAD4 depletion could not be rescued by intraovarian mediators of LH actions, such as epidermal growth factor-like factors and prostaglandin E2. Furthermore, corpus lutea did not form in Smad4(fl/fl);Cyp19-Cre female mice, indicating that SMAD4 was crucial for GCs terminal differentiation. Thus, by characterizing the ovarian phenotypes of preovulatory follicle-specific Smad4 KO mice, we identified the developmental stage-specific functions of the canonical TGF-β signaling pathway in ovulation and luteinization.

The glycan structure in recombinant human FSH affects endocrine activity and global gene expression in human granulosa cells

The aim of this study was to analyse the biological response to different recombinant human FSH (rhFSH) glycosylation variants on the endocrine activity and gene expression at whole-genome scale in human granulosa-like tumor cell line, KGN. The effects of differences in rhFSH sialylation and oligosaccharide complexity were determined on steroid hormone and inhibin production. A microarray approach was used to explore gene expression patterns induced by rhFSH glycosylation variants. Set enrichment analysis revealed that hormone sialylation and oligosaccharide complexity in rhFSH differentially affected the expression of genes involved in essential biological processes and molecular functions of KGN cells. The relevance of rhFSH oligosaccharide structure on steroidogenesis was confirmed assessing gene expression by real time-PCR. The results demonstrate that FSH oligosaccharide structure affects expression of genes encoding proteins, growth factors and hormones essential for granulosa cells function.

Transactivation of microRNA-383 by steroidogenic factor-1 promotes estradiol release from mouse ovarian granulosa cells by targeting RBMS1

Our previous studies have shown that microRNA-383 (miR-383) is one of the most down-regulated miRNA in TGF-β1-treated mouse ovarian granulosa cells (GC). However, the roles and mechanisms of miR-383 in GC function during follicular development remain unknown. In this study, we found that miR-383 was mainly expressed in GC and oocytes of mouse ovarian follicles. Overexpression of miR-383 enhanced estradiol release from GC through targeting RNA binding motif, single stranded interacting protein 1 (RBMS1). miR-383 inhibited RBMS1 by affecting its mRNA stability, which subsequently suppressed the level of c-Myc (a downstream target of RBMS1). Forced expression of RBMS1 or c-Myc attenuated miR-383-mediated steroidogenesis-promoting effects. Knockdown of the transcription factor steroidogenic factor-1 (SF-1) significantly suppressed the expression of Sarcoglycan zeta (SGCZ) (miR-383 host gene), primary and mature miR-383 in GC, indicating that miR-383 was transcriptionally regulated by SF-1. Luciferase and chromatin immunoprecipitation assays revealed that SF-1 specifically bound to the promoter region of SGCZ and directly transactivated miR-383 in parallel with SGCZ. In addition, SF-1 was involved in regulation of miR-383- and RBMS1/c-Myc-mediated estradiol release from GC. These results suggest that miR-383 functions to promote steroidogenesis by targeting RBMS1, at least in part, through inactivation of c-Myc. SF-1 acts as a positive regulator of miR-383 processing and function in GC. Understanding of regulation of miRNA biogenesis and function in estrogen production will potentiate the usefulness of miRNA in the control of reproduction and treatment of some steroid-related disorders.