Expression and distribution of AP-1 transcription factors in the porcine ovary

Single-cell RNA-seq identified novel genes involved in primordial follicle formation

Introduction

The number of primordial follicles (PFs) in mammals determines the ovarian reserve, and impairment of primordial follicle formation (PFF) will cause premature ovarian insufficiency (POI).

Methods

By analyzing public single-cell RNA sequencing performed during PFF on mice and human ovaries, we identified novel functional genes and novel ligand-receptor interaction during PFF. Based on immunofluorescence and in vitro ovarian culture, we confirmed mechanisms of genes and ligand-receptor interaction in PFF. We also applied whole exome sequencing (WES) in 93 cases with POI and whole genome sequencing (WGS) in 465 controls. Variants in POI patients were further investigated by in silico analysis and functional verification.

Results

We revealed ANXA7 (annexin A7) and GTF2F1 (general transcription factor IIF subunit 1) in germ cells to be novel potentially genes in promoting PFF. Ligand Mdk (midkine) in germ cells and its receptor Sdc1 (syndecan 1) in granulosa cells are novel interaction crucial for PFF. Based on immunofluorescence, we confirmed significant up-regulation of ANXA7 in PFs compared with germline cysts, and uniform expression of GTF2F1, MDK and SDC1 during PFF, in 25 weeks human fetal ovary. In vitro investigation indicated that Anxa7 and Gtf2f1 are vital for mice PFF by regulating Jak/Stat3 and Jnk signaling pathways, respectively. Ligand-receptor (Mdk-Sdc1) are crucial for PFF by regulating Pi3k-akt signaling pathway. Two heterozygous variants in GTF2F1, and one heterozygous variants in SDC1 were identified in cases, but no variant were identified in controls. The protein level of GTF2F1 or SDC1 in POI cases are significantly lower than that of controls, indicating the pathogenic effects of the two genes on ovarian function were dosage dependent.

Discussion

Our study identified novel genes and novel ligand-receptor interaction during PFF, and further expanding the genetic architecture of POI.

The Corticosterone–Glucocorticoid Receptor–AP1/CREB Axis Inhibits the Luteinizing Hormone Receptor Expression in Mouse Granulosa Cells

Under stress conditions, luteinizing hormone (LH)-mediated ovulation is inhibited, resulting in insufficient oocyte production and excretion during follicular development. When the body is stressed, a large amount of corticosterone (CORT) is generated, which will lead to a disorder of the body’s endocrine system and damage to the body. Our previous work showed that CORT can block follicular development in mice. Since LH acts through binding with the luteinizing hormone receptor (Lhcgr), the present study aimed to investigate whether and how corticosterone (CORT) influences Lhcgr expression in mouse ovarian granulosa cells (GCs). For this purpose, three-week-old ICR female mice were injected intraperitoneally with pregnant mare serum gonadotropin (PMSG). In addition, the treatment group was injected with CORT (1 mg/mouse) at intervals of 8 h and the control group was injected with the same volume of methyl sulfoxide (DMSO). GCs were collected at 24 h, 48 h, and 55 h after PMSG injection. For in vitro experiments, the mouse GCs obtained from healthy follicles were treated with CORT alone, or together with inhibitors against the glucocorticoid receptor (Nr3c1). The results showed that the CORT caused a downregulation of Lhcgr expression in GCs, which was accompanied by impaired cell viability. Moreover, the effect of the CORT was mediated by binding to its receptor (Nr3c1) in GCs. Further investigation revealed that Nr3c1 might regulate the transcription of Lhcgr through inhibiting the expression of Lhcgr transcription factors, including AP1 and Creb. Taken together, our findings suggested a possible mechanism of CORT-induced anovulation involving the inhibition of Lhcgr expression in GCs by the CORT–Nr3c1–AP1/Creb axis.

Upregulation of Low-Density Lipoprotein Receptor of the Steroidogenesis Pathway in the Cumulus Cells Is Associated with the Maturation of Oocytes and Achievement of Pregnancy

The maturation of the oocyte is influenced by cumulus cells (CCs) and associated with pregnancy rate, whereas the influencing factors have not been completely elucidated in the CCs. In this study, we identified new regulators of CCs for high-quality oocytes and successful pregnancies during assisted reproductive techniques. CCs were collected from cumulus–oocyte complexes (COCs) in young (≤33 years old) and old (≥40 years old) women undergoing intracytoplasmic sperm injection (ICSI) procedures. We screened for factors differentially expressed between young vs. old CCs and pregnancy vs. non-pregnancy using whole mRNA-seq-next-generation sequencing (NGS). We characterized the transcriptome of the CCs to identify factors critical for achieving pregnancy in IVF cycles. Women in the young and old pregnancy groups exhibited the up- and downregulation of multiple genes compared with the non-pregnancy groups, revealing the differential regulation of several specific genes involved in ovarian steroidogenesis in CCs. It was shown that the low-density lipoprotein (LDL) receptor to the steroidogenesis pathway was upregulated in CCs with higher maturity rates of oocytes in the pregnancy group. In conclusion, a higher pregnancy rate is related to the signaling pathway of steroidogenesis by the LDL receptor in infertile women undergoing IVF procedures.

Single-cell transcriptomes reveal heterogeneity of high-grade serous ovarian carcinoma

BACKGROUND

High-grade serous ovarian carcinoma (HGSOC) is the most common and aggressive histotype of epithelial ovarian cancer. The heterogeneity and molecular basis of this disease remain incompletely understood.

METHODS

To address this question, we have performed a single-cell transcriptomics analysis of matched primary and metastatic HGSOC samples.

RESULTS

A total of 13 571 cells are categorized into six distinct cell types, including epithelial cells, fibroblast cells, T cells, B cells, macrophages, and endothelial cells. A subset of aggressive epithelial cells with hyperproliferative and drug-resistant potentials is identified. Several new markers that are highly expressed in epithelial cells are characterized, and their roles in ovarian cancer cell growth and migration are further confirmed. Dysregulation of multiple signaling pathways, including the translational machinery, is associated with ovarian cancer metastasis through the trajectory analysis. Moreover, single-cell regulatory network inference and clustering (SCENIC) analysis reveals the gene regulatory networks and suggests the JUN signaling pathway as a potential therapeutic target for treatment of ovarian cancer, which is validated using the JUN/AP-1 inhibitor T-5224. Finally, our study depicts the epithelial-fibroblast cell communication atlas and identifies several important receptor-ligand complexes in ovarian cancer development.

CONCLUSIONS

This study uncovers new molecular features and the potential therapeutic target of HGSOC, which would advance the understanding and treatment of the disease.

Mechanism underlying the stimulation by IGF-1 of LHCGR expression in porcine granulosa cells

IGF-1 plays important roles in mammalian fertility by promoting cell growth and increasing steroid hormone secretion. Although IGF-1 significantly upregulated luteinizing hormone/choriogonadotropin receptor (LHCGR) gene expression in granulosa cells in a previous study, the mechanism was unclear. The present experiment was designed to primarily explore the regulation of LHCGR expression by IGF-1. First, based on a porcine LHCGR double-luciferase reporter experiment, c-Fos significantly inhibited the activity of the LHCGR promoter. Second, porcine granulosa cells were cultured in vitro with IGF-1, and we observed that the expression of LHCGR was significantly increased and the expression of c-Fos mRNA significantly reduced. After c-Fos overexpression in granulosa cells, IGF-1 attenuated the inhibitory effect of c-Fos on LHCGR. Furthermore, the level of LHCGR mRNA stimulated by IGF-1 in the presence of SB203580 was markedly lower than that of IGF-1 alone action. In conclusion, IGF-1 enhanced the expression of LHCGR by regulating c-Fos in granulosa cells, which may be mediated by the p38MAPK-signaling pathway.

New markers for regulation of transcription and macromolecule metabolic process in porcine oocytes during in vitro maturation

Oocyte maturation is essential for proper fertilization, embryo implantation and early development. While the physiological conditions of these processes are relatively well-known, its exact molecular mechanisms remain widely undiscovered. Oocyte growth, differentiation and maturation are therefore the subject of scientific debate. Precious literature has indicated that the oocyte itself serves a regulatory role in the mechanisms underlying these processes. Hence, the present study performed expression microarrays to analyze the complete transcriptome of porcine oocytes during their in vitro maturation (IVM). Pig material was used for experimentation, as it possesses similarities to the reproductive processes and general genetic proximities of Sus scrofa to human. Oocytes, isolated from the ovaries of slaughtered animals were assessed via the Brilliant Cresyl Blue test and directed to IVM. A number of oocytes were left to be analyzed as the ‘before IVM’ group. Oocyte mRNA was isolated and used for microarray analysis, which was subsequently validated via RT-qPCR. The current study particularly focused on genes belonging to ‘positive regulation of transcription, DNA-dependent’, ‘positive regulation of gene expression’, ‘positive regulation of macromolecule metabolic process’ and ‘positive regulation of transcription from RNA polymerase II promoter’ ontologies. FOS, VEGFA, ESR1, AR, CCND2, EGR2, ENDRA, GJA1, INHBA, IHH, INSR, APP, WWTR1, SMARCA1, NFAT5, SMAD4, MAP3K1, EGR1, RORA, ECE1, NR5A1, KIT, IKZF2, MEF2C, SH3D19, MITF and PSMB4 were all determined to be significantly altered (fold change, >|2|; P<0.05) among these groups, with their downregulation being observed after IVM. Genes with the most altered expressions were analyzed and considered to be potential markers of maturation associated with transcription regulation and macromolecule metabolism process.

FOS, a Critical Downstream Mediator of PGR and EGF Signaling Necessary for Ovulatory Prostaglandins in the Human Ovary

CONTEXT

Fos null mice failed to ovulate and form a corpus luteum (CL) even when given exogenous gonadotropins, suggesting that ovarian Fos expression is critical for successful ovulation and CL formation. However, little is known about FOS in the human ovary.

OBJECTIVES

To determine the expression, regulation, and function of FOS in human periovulatory follicles.

DESIGN/PARTICIPANTS

Timed periovulatory follicles were obtained from normally cycling women. Granulosa/lutein cells were collected from in vitro fertilization patients.

MAIN OUTCOME MEASURES

The in vivo expression after human chorionic gonadotropin (hCG) administration and in vitro regulation of FOS, JUN, JUNB, and JUND was evaluated at the mRNA and protein level. Binding of progesterone receptor (PGR) and FOS to their target genes was assessed by chromatin immunoprecipitation analyses. Prostaglandin E2 (PGE2) and progesterone were measured.

RESULTS

The expression of FOS, JUNB, and JUND drastically increased in ovulatory follicles after hCG administration. In human granulosa/lutein cell cultures, hCG increased the expression of FOS and JUN proteins. Inhibitors of PGR and epidermal growth factor (EGF) receptors reduced hCG-induced increases in the expression and phosphorylation of FOS. PGR bound to the FOS gene. A selective FOS inhibitor blocked hCG-induced increases in PGE2 and the expression of prostaglandin (PG) synthases and transporters (PTGES, SLCO2A1, and ABCC1). FOS bound to the promoter regions of these genes.

CONCLUSIONS

The increase of FOS/activator protein 1 in human periovulatory follicles after hCG administration is mediated by collaborative actions of PGR and EGF signaling and critical for the upregulated expression of key ovulatory genes required for the rise in ovulatory PG in human granulosa cells.

Inhibitors of c-Jun phosphorylation impede ovine primordial follicle activation

STUDY HYPOTHESIS

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

STUDY FINDING

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

WHAT IS KNOWN ALREADY

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

STUDY DESIGN, SAMPLES/MATERIALS, METHODS

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

MAIN RESULTS AND THE ROLE OF CHANCE

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

LIMITATIONS, REASONS FOR CAUTION

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

WIDER IMPLICATIONS OF THE FINDINGS

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

LARGE SCALE DATA

n/a.

STUDY FUNDING AND COMPETING INTERESTS

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

Modulation of expression of 17-Hydroxylase/17,20 lyase (CYP17) and P450 aromatase (CYP19) by inhibition of MEK1 in a human ovarian granulosa-like tumor cell line

The differential steroid production in the theca and granulosa cells in ovary are resulted from unique enzyme expression profiles. Among them, c-fos, a downstream target of mitogen and extracellular signal-regulated kinases (MEK/ERK) signaling, takes part in this compartment. In this study, we investigated the effect of c-fos on the steady-state levels of CYP17 and CYP19 in human ovarian granulosa-like tumor cell line (KGN) by inhibiting MEK/ERK pathway with PD98059. As a result, our finding demonstrated the distinct distribution patterns of CYP17 and CYP19 in KGN. Moreover, the MEK/ERK pathway functions to inhibit the production of CYP17, while enhance the production of CYP19 in granulosa cells, probably involving a c-fos-dependent mechanism. In conclusion, factors such as c-fos may play a crucial role in the down-regulation of CYP17 and up-regulation of CYP19 in granulosa cells, thereby suppressing androstenedione synthesis.

Gene expression analysis of pig cumulus-oocyte complexes stimulated in vitro with follicle stimulating hormone or epidermal growth factor-like peptides

BACKGROUND

The gonadotropin-induced resumption of oocyte meiosis in preovulatory follicles is preceded by expression of epidermal growth factor (EGF)-like peptides, amphiregulin (AREG) and epiregulin (EREG), in mural granulosa and cumulus cells. Both the gonadotropins and the EGF-like peptides possess the capacity to stimulate resumption of oocyte meiosis in vitro via activation of a broad signaling network in cumulus cells. To better understand the rapid genomic actions of gonadotropins (FSH) and EGF-like peptides, we analyzed transcriptomes of cumulus cells at 3 h after their stimulation.

METHODS

We hybridized aRNA from cumulus cells to a pig oligonucleotide microarray and compared the transcriptomes of FSH- and AREG/EREG-stimulated cumulus cells with untreated control cells and vice versa. The identified over- and underexpressed genes were subjected to functional genomic analysis according to their molecular and cellular functions. The expression pattern of 50 selected genes with a known or potential function in ovarian development was verified by real-time qRT-PCR.

RESULTS

Both FSH and AREG/EREG increased the expression of genes associated with regulation of cell proliferation, cell migration, blood coagulation and extracellular matrix remodeling. FSH alone induced the expression of genes involved in inflammatory response and in the response to reactive oxygen species. Moreover, FSH stimulated the expression of genes closely related to some ovulatory events either exclusively or significantly more than AREG/EREG (AREG, ADAMTS1, HAS2, TNFAIP6, PLAUR, PLAT, and HSD17B7). In contrast to AREG/EREG, FSH also increased the expression of genes coding for key transcription factors (CEBPB, FOS, ID1/3, and NR5A2), which may contribute to the differing expression profiles of FSH- and AREG/EREG-treated cumulus cells.

CONCLUSIONS

The impact of FSH on cumulus cell gene transcription was higher than the impact of EGF-like factors in terms of the number of cell functions affected as well as the number of over- and underexpressed genes. Both FSH and EGF-like factors overexpressed genes involved in the post-ovulatory switch in steroidogenesis and tissue remodelling. However, FSH was remarkably more efficient in the up-regulation of several specific genes essential for ovulation of matured oocytes and also genes that been reported to play an important role in maturation of cumulus-enclosed oocytes in vitro.

Gonadotropin and kisspeptin gene expression, but not GnRH, are impaired in cFOS deficient mice

cFOS is a pleiotropic transcription factor, which binds to the AP1 site in the promoter of target genes. In the pituitary gonadotropes, cFOS mediates induction of FSHβ and GnRH receptor genes. Herein, we analyzed reproductive function in the cFOS-deficient mice to determine its role in vivo. In the pituitary cFOS is necessary for gonadotropin subunit expression, while TSHβ is unaffected. Additionally, cFOS null animals have the same sex-steroid levels, although gametogenesis is impeded. In the brain, cFOS is not necessary for GnRH neuronal migration, axon targeting, cell number, or mRNA levels. Conversely, cFOS nulls, particularly females, have decreased Kiss1 neuron numbers and lower Kiss1 mRNA levels. Collectively, our novel findings suggest that cFOS plays a cell-specific role at multiple levels of the hypothalamic-pituitary-gonadal axis, affecting gonadotropes but not thyrotropes in the pituitary, and kisspeptin neurons but not GnRH neurons in the hypothalamus, thereby contributing to the overall control of reproduction.

Expression of factors associated with apoptosis in the porcine corpus luteum throughout the luteal phase of the estrous cycle and early pregnancy: their possible involvement in acquisition of luteolytic sensitivity

The studies on the acquisition of luteolytic sensitivity have been focused mainly on molecular changes induced in the luteal tissue after treatment with exogenous PGF2α or on physiological changes occurring during the estrous cycle. The comparison of changes leading to the acquisition of luteolytic sensitivity after Day 12 of the estrous cycle and corresponding days of pregnancy has not been investigated in the pig. The present study was undertaken to evaluate (1) apoptosis measured as the proportions of early apoptotic, late apoptotic, and viable cells; (2) expression of factors involved in the extrinsic (TNFA/TNFα, TNFRSF1A/TNFR1, TNFRSF1B/TNFR2, FAS/Fas, and FASLG/FasL) and intrinsic (CASP3/Casp3, TP53/p-53, BAX/Bax, and BCL2/Bcl-2) apoptotic pathways, with two components of the activating protein-1 complex, i.e., FOS/Fos and JUN/Jun and IFNG/IFNγ; and (3) concentrations of luteal and blood plasma progesterone (P4) throughout the luteal phase of the estrous cycle and early pregnancy. Corpora lutea (CL) were collected postmortem on Days 8, 10, 12, and 14 of the estrous cycle and the corresponding days of pregnancy. The luteal tissue was subjected to RNA and/or protein isolation and disaggregation of CL cells followed by flow cytometry analysis aimed to determine apoptotic changes. Luteal and blood plasma P4 concentrations decreased on Day 14 of the estrous cycle versus pregnancy (P < 0.05 and P < 0.001, respectively). A significant increase in the number of early apoptotic cells and a decrease in the number of viable cells were observed on Day 14 of the estrous cycle (P < 0.001 and P < 0.05, respectively). Increase (P < 0.05) of TNFA messenger RNA (mRNA) level coincided with that of IFNG on Day 12 of the estrous cycle but not on the corresponding day of pregnancy. The content of FAS mRNA and protein increased on Day 14 of the estrous cycle versus pregnancy (P < 0.05). The mRNA expression of CASP3, BCL-2 and BAX was unchanged in cyclic and pregnant CL, while level of TP53 increased (P < 0.05) on Day 12 of the estrous cycle versus Day 8. The level of FOS and JUN mRNA increased (P < 0.05) on Day 14 of the estrous cycle versus the remaining days. The level of FOS and JUN mRNA was significantly higher (P < 0.001 and P < 0.05, respectively) on Day 14 of the estrous cycle than that on the corresponding day of pregnancy. In summary, the simultaneous increase of TNFA and IFNG transcript in cyclic CL suggests the crucial role of both cytokines in sensitization of porcine CL to further luteolytic action of PGF2α. The upregulated expression of FAS, FOS, and JUN mRNA in the late luteal phase in cyclic CL can indicate their involvement in structural luteolysis. The increased viability of luteal cells and elevated P4 concentrations in pregnant CL confirm the protective role of luteal P4 against apoptosis.

Oxidative stress--implications, source and its prevention

Oxidative stress has been a major predicament of present day living. It has been the product of imbalance between the processes involved in free radical generation and their neutralization by enzymatic and non-enzymatic defence mechanisms. The oxidative stress has been contributed by numerous factors including heavy metals, organic compound-rich industrial effluents, air pollutants and changing lifestyle pattern focussing mainly on alcohol consumption, dietary habits, sun exposure, nuclear emissions, etc. The most common outcome of oxidative stress is the increased damage of lipid, DNA and proteins that resulted in the development of different pathologies. Among these pathologies, cancer is the most devastating and linked to multiple mutations arising due to oxidative DNA and protein damage that ultimately affect the integrity of the genome. The chemopreventive agents particularly nutraceuticals are found to be effective in reducing cancer incidences as these components have immense antioxidative, antimutagenic and antiproliferative potentials and are an important part of our dietary components. These secondary metabolites, due to their unique chemical structure, facilitate cell-to-cell communication, repair DNA damage by the downregulation of transcription factors and inhibit the activity of protein kinases and cytochrome P450-dependent mixed function oxidases. These phytochemicals, therefore, are most appropriate in combating oxidative stress-related disorders due to their tendency to exert better protective effect without having any distinct side effect.

Differential gene expression of granulosa cells after ovarian superstimulation in beef cattle

Microarray analysis was used to compare the gene expression of granulosa cells from dominant follicles with that of those after superstimulatory treatment. Cows were allocated randomly to two groups (superstimulation and control, n=6/group). A new follicular wave was induced by ablation of follicles ≥5 mm in diameter, and a progesterone-releasing device controlled internal drug release (CIDR) was placed in the vagina. The superstimulation group was given eight doses of 25 mg FSH at 12-h intervals starting from the day of wave emergence (day 0), whereas the control group was not given FSH treatment. Both groups were given prostaglandin F2α twice, 12 h apart, on day 3 and the CIDR was removed at the second injection; 25 mg porcine luteinizing hormone (pLH) was given 24 h after CIDR removal, and cows were ovariectomized 24 h later. Granulosa cells were collected for RNA extraction, amplification, and microarray hybridization. A total of 190 genes were downregulated and 280 genes were upregulated. To validate the microarray results, five genes were selected for real-time PCR (NTS, FOS, THBS1, FN1, and IGF2). Expression of four genes increased significantly in the three different animals tested (NTS, FOS, THBS1, and FN1). The upregulated genes are related to matrix remodeling (i.e. tissue proliferation), disturbance of angiogenesis, apoptosis, and oxidative stress response. We conclude that superstimulation treatment i) results in granulosa cells that lag behind in maturation and differentiation (most of the upregulated genes are markers of the follicular growth stage), ii) activates genes involved with the NFE2L2 oxidative stress response and endoplasmic reticulum stress response, and iii) disturbs angiogenesis.

Prostaglandin F2α regulation of mRNA for activating protein 1 transcriptional factors in porcine corpora lutea (CL): lack of induction of JUN and JUND in CL without luteolytic capacity

Porcine corpora lutea (CL) develop sensitivity to regression by prostaglandin F2α (PGF2α), termed luteolytic capacity, about 13 d after estrus. We postulated that PGF2α regulation of activating protein 1 (AP-1) transcriptional factor expression underlies acquisition of luteolytic capacity. CL were collected from gilts on day 9 (estrous cycle) or day 17 (pseudopregnancy) before or after PGF2α treatment with mRNA measured for FOS, FOSB, FOSL1, FOSL2, JUN, JUNB, and JUND and the AP-1 target genes CCL2 and SERPINE1. At 0.5 h after PGF2α, both day-9 and day-17 CL had increased (P < 0.01) mRNA for FOS (2,225% and 1,817%), JUNB (237% and 358%), and FOSB (1,060% and 925%). Intriguingly, at 0.5 h after PGF2α there was increased (P < 0.01) mRNA encoding JUN (1,099%) and JUND (300%) in day-17 but not day-9 CL. At 10 h after PGF2α there was elevated FOSB mRNA in day-17 (771%) but not day-9 CL and no PGF2α-induced change in FOS, JUN, JUND, and JUNB mRNA in day-9 or day-17 CL. Treatment with PGF2α increased mRNA for AP-1-responsive genes, CCL2 at 0.5 h (202%) and CCL2 and SERPINE1 at 10 h (719% and 1,515%), only in day-17 CL. Thus, many of the fos family of transcription factors are dramatically induced by PGF2α in CL with or without luteolytic capacity. However, PGF only induced JUN and JUND expression in CL with luteolytic capacity, a finding that may be key for understanding the acquisition of luteolytic capacity, given that JUN is the only AP-1 family member with strong N-terminal trans-activation activity.

Activating protein-1 family of transcription factors in the human placenta complicated by preeclampsia with and without fetal growth restriction

Preeclampsia (PE) is a serious disorder of human pregnancy, it is often associated with fetal growth restriction (FGR) which is a failure of the fetus to reach its own growth potential. Activator protein-1 (AP-1) is a family of transcription factors inducible in response to a variety of extracellular stimuli and functions. AP-1 plays a complex role in the regulation of different fundamental cellular processes, including cell proliferation, survival, death and transformation. We investigate the expression pattern of AP-1 transcription factors in normal placentas during gestation and in placentas from PE without and with FGR using semiquantitative RT-PCR and immunohistochemistry techniques. The most interesting data concern the alterations of protein expression patterns of c-fos, Jun D and c-jun in normal gestation as well as in PE and PE-FGR pathologies. In addition, alterations but not significant changes are detected in mRNA expressions for these transcription factors. We strongly suggest that c-fos is implicated in regulating invasiveness mechanism of extravillous trophoblast in normal gestation as well as in PE placentas. In addition, we suggest that the opposite modulation of Jun D and c-jun in PE and PE-FGR supports the recent hypothesis that PE and PE-FGR could be considered two pathologies with different origin (maternal and placental) each of which has a different molecular pattern of expression.

Molecular mechanism for repression of 17alpha-hydroxylase expression and androstenedione production in granulosa cells

CONTEXT

According to the traditional two-cell two-gonadotropin model of follicular steroidogenesis, androgen production arises exclusively from theca cells. The granulosa cells, in turn, utilize androstenedione and testosterone, which are aromatized into estrone and estradiol, respectively. Differential expression of the activator protein-1 (AP-1) transcription factor, c-fos, has been postulated to result in distinct patterns of steroidogenesis in the theca and granulosa cell compartments. We hypothesize that c-fos functions to inhibit the production of 17alpha-hydroxylase 17,20 lyase (CYP17) in granulosa cells, thereby suppressing androgen synthesis.

OBJECTIVE

Our objective was to define the role of c-fos in the regulation of CYP17 production in granulosa cells.

DESIGN AND METHODS

Human luteinized granulosa (HGL5) cells were utilized for all experiments. The following techniques were used: mRNA extraction, steroid quantification, small interfering RNA silencing, microarray analysis, and immunohistochemistry.

RESULTS

Immunohistochemistry studies demonstrated significant staining of c-fos in the granulosa cell layer, but absent staining for CYP17. Conversely, the theca cell layer did not stain for c-fos, but staining was evident for CYP17. Treatment of HGL5 cells with the MAPK kinase inhibitor PD98059 resulted in an 11-fold increase in CYP17 mRNA levels. In c-fos gene silenced cells, CYP17 mRNA levels increased 8-fold. Androstenedione production was increased 13-fold after treatment with PD98059.

CONCLUSIONS

These results suggest that the AP-1 transcription factor, c-fos, may be one of the factors responsible for CYP17 repression and hence suppression of androstenedione production in granulosa cells. This may provide an explanation for the lack of CYP17 in granulosa cells.

Transcription of steroidogenic acute regulatory protein in the rodent ovary and placenta: alternative modes of cyclic adenosine 3', 5'-monophosphate dependent and independent regulation

Steroid hormone synthesis is a vital function of the adrenal cortex, serves a critical role in gonadal function, and maintains pregnancy if normally executed in the placenta. The substrate for the synthesis of all steroid hormones is cholesterol, and its conversion to the first steroid, pregnenolone, by the cholesterol side-chain cleavage cytochrome P450 (CYP11A1) enzyme complex takes place in the inner mitochondrial membranes. Steroidogenic acute regulatory protein (STAR) facilitates the rate-limiting transfer of cholesterol from the outer mitochondrial membrane to CYP11A1 located in the inner organelle membranes. The current study explored the mechanisms controlling transcription of the Star gene in primary cell cultures of mouse placental trophoblast giant cells and rat ovarian granulosa cells examined throughout the course of their functional differentiation. Our findings show that the cis-elements required for Star transcription in the rodent placenta and the ovary are centered in a relatively small proximal region of the promoter. In placental trophoblast giant cells, cAMP is required for activation of the Star promoter, and the cis-elements mediating a maximal response were defined as cAMP response element 2 and GATA. EMSA studies show that placental cAMP-responsive element binding protein (CREB)-1 and activating transcription factor-2 (ATF2) bind to a -81/-78 sequence, whereas GATA-2 binds to a -66/-61 sequence. In comparison, patterns of Star regulation in the ovary suggested tissue-specific and developmental controlled modes of Star transcription. During the follicular phase, FSH/cAMP induced CREB-1 dependent activity, whereas upon luteinization STAR expression becomes cAMP and CREB independent, a functional shift conferred by FOS-related antigen-2 displacement of CREB-1 binding, and the appearance of a new requirement for CCAAT enhancer-binding protein beta and steroidogenic factor 1 that bind to upstream elements (-117/-95). These findings suggest that during evolution, the promoters of the Star gene acquired nonconsensus sequence elements enabling expression of a single gene in different organs, or allowing dynamic temporal changes corresponding to progressing phases of differentiation in a given cell type.

The mechanism for protein kinase C inhibition of androgen production and 17alpha-hydroxylase expression in a theca cell tumor model

INTRODUCTION

In polycystic ovary syndrome (PCOS), there is increased formation of androgens by thecal cells. Moreover, PCOS ovaries have been shown to have decreased levels of c-fos transcription factor. We hypothesize that c-fos expression inhibits 17alpha-hydroxylase 17,20 lyase (CYP17) activity in the human ovary, and its decreased expression seen in PCOS may lead to elevated CYP17 transcription, resulting in increased androgen production.

OBJECTIVE

Our objective was to define the role of the activator protein-1 transcription factors, namely c-fos, in the regulation of CYP17 expression in theca cells.

METHODS

Human ovarian thecal-like tumor cells were used for all experiments. The following techniques were used: steroid quantification, mRNA extraction, microarray analysis, transfection, small interfering RNA, and immunohistochemistry.

RESULTS

Stimulation of human ovarian thecal-like tumor cells with the protein kinase A pathway activator forskolin resulted in stimulation of C19 androgen production. In contrast, treatment with the protein kinase C pathway activator tetradecanoylphorbol acetate (TPA) resulted in decreased androgen production with a shift toward C21 progesterone production. TPA also led to complete inhibition of CYP17. Microarray data showed a 37-fold increase in c-fos after treatment with TPA. Transfection with steroidogenic factor 1 resulted in an increase in CYP17 promoter activity, which was significantly inhibited in the presence of c-fos. c-fos gene silencing led to an increase in CYP17 mRNA levels. Immunohistochemical staining for c-fos in ovaries demonstrated strong staining in granulosa cells, but not theca.

CONCLUSIONS

The activator protein-1 transcription factor c-fos plays a role in the inhibition of CYP17 expression. The decreased levels of c-fos expression in polycystic ovaries may be responsible for increased CYP17 levels in PCOS.

Biphasic regulation of AP-1 subunits during human epidermal wound healing

Cutaneous wound healing is a well-coordinated process that includes inflammation, proliferation, and differentiation. Activator protein 1 (AP-1) subunits have been implicated in the regulation of genes important for these processes and have been shown to be involved in wound healing. However, investigation of human healing and non-healing wounds in vivo and ex vivo, and the comparative analysis of several members of the Jun and Fos families are still missing. Here, we show that normal human epidermal wound healing is biphasic. In the first phase all AP-1 subunits investigated, that is c-Jun, Jun B, Jun D, c-Fos, and Fos B are absent from the nuclei at the wound margins/leading edges. This downregulation coincides with that of the gap junction protein connexin 43. Later on, c-Jun, Jun B, Jun D, and c-Fos reappear in the nuclei of the leading edges in a time-dependent manner. In non-healing wounds, a more intensive staining of keratinocytes at the wound margins is often observed. Our findings suggest that coordinated down- and upregulation of the various AP-1 subunits in the course of epidermal wound healing is important for its undisturbed progress, putatively by influencing inflammation and cell-cell communication.

Fra1 activity in the frog, Rana esculenta, testis: a new potential role in sperm transport

Using an anti-Fos family member antibody, we have previously described in Rana esculenta testis the presence of a nuclear, 43 kDa protein that we hypothesized to be Fra1. With the assistance of an antibody against Fra1 that does not cross-react with other Fos family members, here we report data on Fra1 expression, localization, and putative activity in Rana esculenta testis during its annual reproductive cycle. Western blot analysis confirms that the nuclear, 43 kDa protein is Fra1. Immunocytochemistry validates the Western blot results and shows cytoplasmic and nuclear immunostaining of Fra1 in peritubular myoid cells, efferent ducts, and blood vessels. We report for the first time in a vertebrate, experimental evidence showing that the expression of Fra1 is related to peritubular myoid cells during sperm transport from the tubular compartment to efferent ducts.

Tumor necrosis factor alpha (TNF) increases granulosa cell proliferation: dependence on c-Jun and TNF receptor type 1

TNF alpha has significant in vitro effects on steroidogenesis and folliculogenesis and reproductive alterations occur in TNF receptor type 1 (TNFR1) knockout mice. The present study investigated the effect of in vitro TNF on granulosa cell proliferation from immature mice at 28 d of age, with emphasis on intracellular signaling that regulates granulosa cell proliferation. TNF dose dependently increased granulosa cell proliferation and the proto-oncogene c-Jun protein. However, other Jun family members such as JunD was expressed constitutively and JunB was not expressed. In vitro TNF did not increase c-Jun and proliferation in granulosa cells from TNFR1 knockout mice. The time course of TNF-induced c-Jun revealed biphasic patterns of short-term (3 h) and long-term (24 h) induction. The time courses of Ser63- and Ser73-phospho c-Jun coincided with changes in total c-Jun. Among MAPK cascades, stress-activated protein kinase/c-Jun-NH(2)-teminal kinase signaling was increased transiently in TNF-treated cells, whereas p38MAPK and ERK1 and 2 were not changed. In addition, overexpression of nuclear factor-kappa B and addition of ceramide and 8-bromo-cAMP did not increase c-Jun or proliferation. Antisense oligonucleotides for c-Jun blocked cell proliferation induced by TNF. In conclusion, the above results demonstrate that TNF increased c-Jun by activating stress-activated protein kinase/c-Jun-NH(2)-teminal kinase signaling via TNFR1 in mouse granulosa cells, and the induced c-Jun resulted in increased cell proliferation.