Jun proteins modulate the ovary-specific promoter of aromatase gene in ovarian granulosa cells via a cAMP-responsive element

JunB condensation attenuates vascular endothelial damage under hyperglycemic condition

Endothelial damage is the initial and crucial factor in the occurrence and development of vascular complications in diabetic patients, contributing to morbidity and mortality. Although hyperglycemia has been identified as a damaging effector, the detailed mechanisms remain elusive. In this study, identified by ATAC-seq and RNA-seq, JunB reverses the inhibition of proliferation and the promotion of apoptosis in human umbilical vein endothelial cells treated with high glucose, mainly through the cell cycle and p53 signaling pathways. Furthermore, JunB undergoes phase separation in the nucleus and in vitro, mediated by its intrinsic disordered region and DNA-binding domain. Nuclear localization and condensation behaviors are required for JunB-mediated proliferation and apoptosis. Thus, our study uncovers the roles of JunB and its coacervation in repairing vascular endothelial damage caused by high glucose, elucidating the involvement of phase separation in diabetes and diabetic endothelial dysfunction.

Unveiling Key Biomarkers and Therapeutic Drugs in Polycystic Ovary Syndrome (PCOS) Through Pathway Enrichment Analysis and Hub Gene-miRNA Networks

Background

Polycystic ovary syndrome (PCOS) affects women of reproductive age globally with an incidence rate of 5% - 26%. Growing evidence reports important roles for microRNAs (miRNAs) in the pathophysiology of granulosa cells (GCs) in PCOS.

Objectives

The objectives of this study were to identify the top differentially expressed miRNAs (DE-miRNAs) and their corresponding targets in hub gene-miRNA networks, as well as identify novel DE-miRNAs by analyzing three distinct microarray datasets. Additionally, functional enrichment analysis was performed using bioinformatics approaches. Finally, interactions between the 5 top-ranked hub genes and drugs were investigated.

Methods

Using bioinformatics approaches, three GC profiles from the gene expression omnibus (GEO), namely gene expression omnibus series (GSE)-34526, GSE114419, and GSE137684, were analyzed. Targets of the top DE-miRNAs were predicted using the multiMiR R package, and only miRNAs with validated results were retrieved. Genes that were common between the "DE-miRNA prediction results" and the "existing tissue DE-mRNAs" were designated as differentially expressed genes (DEGs). Gene ontology (GO) and pathway enrichment analyses were implemented for DEGs. In order to identify hub genes and hub DE-miRNAs, the protein-protein interaction (PPI) network and miRNA-mRNA interaction network were constructed using Cytoscape software. The drug-gene interaction database (DGIdb) database was utilized to identify interactions between the top-ranked hub genes and drugs.

Results

Out of the top 20 DE-miRNAs that were retrieved from the GSE114419 and GSE34526 microarray datasets, only 13 of them had "validated results" through the multiMiR prediction method. Among the 13 DE-miRNAs investigated, only 5, namely hsa-miR-8085, hsa-miR-548w, hsa-miR-612, hsa-miR-1470, and hsa-miR-644a, demonstrated interactions with the 10 hub genes in the hub gene-miRNA networks in our study. Except for hsa-miR-612, the other 4 DE-miRNAs, including hsa-miR-8085, hsa-miR-548w, hsa-miR-1470, and hsa-miR-644a, are novel and had not been reported in PCOS pathogenesis before. Also, GO and pathway enrichment analyses identified "pathogenic E. coli infection" in the Kyoto encyclopedia of genes and genomes (KEGG) and "regulation of Rac1 activity" in FunRich as the top pathways. The drug-hub gene interaction network identified ACTB, JUN, PTEN, KRAS, and MAPK1 as potential targets to treat PCOS with therapeutic drugs.

Conclusions

The findings from this study might assist researchers in uncovering new biomarkers and potential therapeutic drug targets in PCOS treatment.

Chronic superphysiologic AMH promotes premature luteinization of antral follicles in human ovarian xenografts

Anti-Müllerian hormone (AMH) is produced by growing ovarian follicles and provides a diagnostic measure of reproductive reserve in women; however, the impact of AMH on folliculogenesis is poorly understood. We cotransplanted human ovarian cortex with control or AMH-expressing endothelial cells in immunocompromised mice and recovered antral follicles for purification and downstream single-cell RNA sequencing of granulosa and theca/stroma cell fractions. A total of 38 antral follicles were observed (19 control and 19 AMH) at long-term intervals (>10 weeks). In the context of exogenous AMH, follicles exhibited a decreased ratio of primordial to growing follicles and antral follicles of increased diameter. Transcriptomic analysis and immunolabeling revealed a marked increase in factors typically noted at more advanced stages of follicle maturation, with granulosa and theca/stroma cells also displaying molecular hallmarks of luteinization. These results suggest that superphysiologic AMH alone may contribute to ovulatory dysfunction by accelerating maturation and/or luteinization of antral-stage follicles.

sox19 regulates ovarian steroidogenesis in common carp

In teleost, ovarian steroidogenesis governed by the neuroendocrine system is also regulated by several transcription factors of gonadal origin. Investigating the synchronized interactions between the transcriptional and the hormonal factors is vital to comprehend the mechanisms that lead to gonadal differentiation. This study signifies the role of sry-related box (sox) 19 in ovarian steroidogenesis regulation of the common carp, Cyprinus carpio. Analysis of tissue distribution displayed higher sox19 expression in brain and ovary, and gonadal ontogeny showed higher expression of sox19 at 80 days post hatch (dph). Higher sox19 mRNA expression during spawning and increase of sox19 post human chorionic gonadotropin induction substantiate gonadotropin dependency. Estradiol-17β treatment but not 17α-methyl-di-hydroxy-testosterone to 50 dph common carp for inducing mono-sex, elevated sox19 expression substantially. Sox19 protein was observed in granulosa cells of the follicular layer in common carp ovary. Higher sox19 expression was detected in isolated granulosa and theca cells, in vitro. Transient gene silencing with sox19-siRNA caused downregulation of various ovary-related genes including those specific to activator protein-1 factors, fibroblast growth factors, wnt-signaling, steroidogenic genes along with certain transcription factors. Serum 17α, 20β-dihydroxy-4-pregnen-3-one and estradiol-17β reduced significantly post sox19 silencing, in vivo. Concomitantly, a decrease in aromatase activity was detected post sox19-siRNA treatment, in vivo. This study demonstrates the impact of sox19 in the regulation of common carp ovarian growth and steroidogenesis.

Positive effects of amphiregulin on human oocyte maturation and its molecular drivers in patients with polycystic ovary syndrome

STUDY QUESTION

Does use of medium containing amphiregulin improve meiotic maturation efficiency in oocytes of women with polycystic ovary syndrome (PCOS) undergoing in vitro maturation (IVM) preceded by a capacitation culture step capacitation IVM (CAPA-IVM)?

SUMMARY ANSWER

Use of medium containing amphiregulin significantly increased the maturation rate from oocytes retrieved from follicles with diameters <6 or ≥6 mm pre-cultured in capacitation medium.

WHAT IS KNOWN ALREADY

Amphiregulin concentration in follicular fluid is correlated with human oocyte developmental competence. Amphiregulin added to the meiotic trigger has been shown to improve outcomes of IVM in a range of mammalian species.

STUDY DESIGN, SIZE, DURATION

This prospective, randomized cohort study included 30 patients and was conducted at an academic infertility centre in Vietnam from April to December 2019. Patients with PCOS were included.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In the first stage, sibling oocytes from each patient (671 in total) were allocated in equal numbers to maturation in medium with (CAPA-AREG) or without (CAPA-Control) amphiregulin 100 ng/ml. After a maturation check and fertilization using intracytoplasmic sperm injection (ICSI), all good quality Day 3 embryos were vitrified. Cumulus cells (CCs) from both groups were collected at the moment of ICSI denudation and underwent a molecular analysis to quantify key transcripts of oocyte maturation and to relate these to early embryo development. On return for frozen embryo transfer (second stage), patients were randomized to have either CAPA-AREG or CAPA-Control embryo(s) implanted. Where no embryo(s) from the randomized group were available, embryo(s) from the other group were transferred. The primary endpoint of the study was meiotic maturation efficiency (proportion of metaphase II [MII] oocytes; maturation rate).

MAIN RESULTS AND THE ROLE OF CHANCE

In the per-patient analysis, the number of MII oocytes was significantly higher in the CAPA-AREG group versus the CAPA-Control group (median [interquartile range] 7.0 [5.3, 8.0] versus 6.0 [4.0, 7.0]; P = 0.01). When each oocyte was evaluated, the maturation rate was also significantly higher in the CAPA-AREG group versus the CAPA-Control group (67.6% versus 55.2%; relative risk [RR] 1.22 [95% confidence interval (CI) 1.08-1.38]; P = 0.001). No other IVM or embryology outcomes differed significantly between the two groups. Rates of clinical pregnancy (66.7% versus 42.9%; RR 1.56 [95% CI 0.77-3.14]), ongoing pregnancy (53.3% versus 28.6%; RR 1.87 [95% CI 0.72-4.85]) and live birth (46.7% versus 28.6%; RR 1.63 [95% CI 0.61-4.39]) were numerically higher in the patients who had CAPA-AREG versus CAPA-Control embryos implanted, but each fertility and obstetric outcome did not differ significantly between the groups. In the CAPA-AREG group, there were significant shifts in CC expression of genes involved in steroidogenesis (STAR, 3BHSD), the ovulatory cascade (DUSP16, EGFR, HAS2, PTGR2, PTGS2, RPS6KA2), redox and glucose metabolism (CAT, GPX1, SOD2, SLC2A1, LDHA) and transcription (NRF2). The expression of three genes (TRPM7, VCAN and JUN) in CCs showed a significant correlation with embryo quality.

LIMITATIONS, REASONS FOR CAUTION

This study included only Vietnamese women with PCOS, limiting the generalizability. Although 100 ng/ml amphiregulin addition to the maturation culture step significantly improved the MII rate, the sample size in this study was small, meaning that these findings should be considered as exploratory. Therefore, a larger patient cohort is needed to confirm whether the positive effects of amphiregulin translate into improved fertility outcomes in patients undergoing IVM.

WIDER IMPLICATIONS OF THE FINDINGS

Data from this study confirm the beneficial effects of amphiregulin during IVM with respect to the trigger of oocyte maturation. The gene expression findings in cumulus indicate that multiple pathways might contribute to these beneficial effects and confirm the key role of the epidermal growth factor system in the stepwise acquisition of human oocyte competence.

STUDY FUNDING/COMPETING INTEREST(S)

This work was funded by the Vietnam National Foundation for Science and Technology Development (NAFOSTED; grant number FWO.106-YS.2017.02) and by the Fund for Research Flanders (FWO; grant number G.OD97.18N). L.N.V. has received speaker and conference fees from Merck, grants, speaker and conference fees from Merck Sharpe and Dohme, and speaker, conference and scientific board fees from Ferring. T.M.H. has received speaker fees from Merck, Merck Sharp and Dohme and Ferring. J.S. reports speaker fees from Ferring Pharmaceuticals and Biomérieux Diagnostics and grants from FWO Flanders, is co-inventor on granted patents on CAPA-IVM methodologies in USA (US10392601B2), Europe (EP3234112B1) and Japan (JP 6806683 registered 08-12-2020) and is a co-shareholder of Lavima Fertility Inc., a spin-off company of the Vrije Universiteit Brussel (VUB, Brussels, Belgium). NA, TDP, AHL, MNHN, SR, FS, EA and UDTH report no financial relationships with any organizations that might have an interest in the submitted work in the previous three years, and no other relationships or activities that could appear to have influenced the submitted work.

TRIAL REGISTRATION NUMBER

NCT03915054.

Transcriptome profile of goat folliculogenesis reveals the interaction of oocyte and granulosa cell in correlation with different fertility population

To understand the molecular and genetic mechanisms related to the litter size in one species of two different populations (high litter size and low litter size), we performed RNA-seq for the oocytes and granulosa cells (GCs) at different developmental stages of follicle, and identified the interaction of genes from both sides of follicle (oocyte and GCs) and the ligand-receptor pairs from these two sides. Our data were very comprehensive to uncover the difference between these two populations regarding the folliculogenesis. First, we identified a set of potential genes in oocyte and GCs as the marker genes which can be used to determine the goat fertility capability and ovarian reserve ability. The data showed that GRHPR, GPR84, CYB5A and ERAL1 were highly expressed in oocyte while JUNB, SCN2A, MEGE8, ZEB2, EGR1and PRRC2A were highly expressed in GCs. We found more functional genes were expressed in oocytes and GCs in high fertility group (HL) than that in low fertility group (LL). We uncovered that ligand-receptor pairs in Notch signaling pathway and transforming growth factor-β (TGF-β) superfamily pathways played important roles in goat folliculogenesis for the different fertility population. Moreover, we discovered that the correlations of the gene expression in oocytes and GCs at different stages in the two populations HL and LL were different, too. All the data reflected the gene expression landscape in oocytes and GCs which was correlated well with the fertility capability.

Transcriptional regulation of CYP19 by cohesin-mediated chromosome tethering in human granulosa cells

Human CYP19 spans a region of chromosome 15 of approximately 130 kb and encodes aromatase, an enzyme required for estrogen synthesis. In the human granulosa cell-line KGN, there are seven open chromatin regions within the CYP19 locus. In this study, we demonstrate that two of these regions ~40 kb upstream and ~15 kb downstream of the CYP19 promoter are cohesin-loading sites, physically interacting with the promoter to negatively and positively regulate transcription, respectively. These observations suggest that CYP19 expression is controlled by a balance between the upstream silencer and downstream enhancer. When cohesin is depleted, CYP19 expression is elevated since the silencer is 2.5-fold further from the promoter than the enhancer and most likely depends on cohesin-mediated tethering to influence expression.

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Silencer and enhancer elements of CYP19 were identified in the human granulosa cell-line KGN.

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The silencer and enhancer elements both interacted with the CYP19 promoter through cohesin-mediated chromosome tethering.

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A balance between the activity of the silencer and enhancer element controls CYP19 expression.

Estrogen disorders: Interpreting the abnormal regulation of aromatase in granulosa cells (Review)

Ovarian granulosa cells (GCs) are the most important source of estrogen. Therefore, aromatase (estrogen synthase), which is the key enzyme in estrogen synthesis, is not only an important factor of ovarian development, but also the key to estrogen secretion by GCs. Disorders of the ovarian estrogen secretion are more likely to induce female estrogen-dependent diseases and fertility issues, such as ovarian cancer and polycystic ovary syndrome. Hence, aromatase is an important drug target; treatment with its inhibitors in estrogen-dependent diseases has attracted increasing attention. The present review article focuses on the regulation and mechanism of the aromatase activity in the GCs, as well as the specific regulation of aromatase promoters. In GCs, follicle-stimulating hormone (FSH) is dependent on the cyclic adenosine monophosphate (cAMP) pathway to regulate the aromatase activity, and the regulation of this enzyme is related to the activation of signaling pathways, such as phosphatidylinositol 3-kinase (PI3K) and extracellular signal-regulated kinase (ERK). In addition, endocrine-disrupting substance and other related factors affect the expression of aromatase, which eventually create an imbalance in the estrogen secretion by the target tissues. The present review highlights these useful factors as potential inhibitors for target therapy.

Estrogen Attenuates the Growth of Human Papillomavirus-Positive Epithelial Cells

Human papillomaviruses cause around 5% of all human cancers, yet there are no specific antiviral therapeutic approaches available for combatting these cancers. These cancers are currently treated with standard chemoradiation therapy (CRT). Specific antiviral reagents are desperately required, particularly for HPV+HNSCC whose incidence is increasing and for which there are no diagnostic tools available for combatting this disease. Using data from The Cancer Genome Atlas (TCGA), we and others determined that the estrogen receptor alpha (ERα) is overexpressed in HPV+HNSCC and that elevated levels are associated with an improved disease outcome. This has led to the proposal that estrogen treatment could be a novel therapeutic approach for combatting HPV+cancers. Here, we demonstrate that estrogen attenuates the growth of HPV+epithelial cells using multiple mechanisms, supporting the idea that estrogen has potential as a therapeutic agent for the treatment of HPV+HNSCC.

Human papillomaviruses (HPVs) are small, double-stranded DNA viruses that are significant risk factors in the development of cancer, and HPV accounts for approximately 5% of all worldwide cancers. Recent studies using data from The Cancer Genome Atlas (TCGA) have demonstrated that elevated levels of estrogen receptor alpha (ERα) are associated with improved survival in oropharyngeal cancers, and these elevated receptor levels were linked with human papillomavirus-positive cancers (HPV+cancers). There has been a dramatic increase in HPV-related head and neck squamous cell carcinomas (HPV+HNSCCs) over the last 2 decades, and therapeutic options for this ongoing health crisis are a priority; currently, there are no antiviral therapeutics available for combatting HPV+cancers. During our TGCA studies on head and neck cancer, we had also discovered the overexpression of ERα in HPV+cancers. Here, we demonstrate that 17β-estradiol (estrogen) attenuates the growth/cell viability of HPV+cancers in vitro, but not HPV-negative cancer cells. In addition, N/Tert-1 cells (foreskin keratinocytes immortalized with human telomerase reverse transcriptase [hTERT]) containing human papillomavirus 16 (HPV16) have elevated levels of ERα and growth sensitivity after estrogen treatment compared with parental N/Tert-1 cells. Finally, we demonstrate that there are potentially two mechanisms contributing to the attenuation of HPV+ cell growth following estrogen treatment. First, estrogen represses the viral transcriptional long control region (LCR) downregulating early gene expression, including E6/E7. Second, expression of E6 and E7 by themselves sensitizes cells to estrogen. Overall, our results support the recent proposal that estrogen could be exploited therapeutically for the treatment of HPV-positive oral cancers.

IMPORTANCE Human papillomaviruses cause around 5% of all human cancers, yet there are no specific antiviral therapeutic approaches available for combatting these cancers. These cancers are currently treated with standard chemoradiation therapy (CRT). Specific antiviral reagents are desperately required, particularly for HPV+HNSCC whose incidence is increasing and for which there are no diagnostic tools available for combatting this disease. Using data from The Cancer Genome Atlas (TCGA), we and others determined that the estrogen receptor alpha (ERα) is overexpressed in HPV+HNSCC and that elevated levels are associated with an improved disease outcome. This has led to the proposal that estrogen treatment could be a novel therapeutic approach for combatting HPV+cancers. Here, we demonstrate that estrogen attenuates the growth of HPV+epithelial cells using multiple mechanisms, supporting the idea that estrogen has potential as a therapeutic agent for the treatment of HPV+HNSCC.

Modulation of estrogen synthesis and metabolism by phytoestrogens in vitro and the implications for women's health

Phytoestrogens are increasingly used as dietary supplements due to their suggested health promoting properties, but also by women for breast enhancement and relief of menopausal symptoms. Generally, phytoestrogens are considered to exert estrogenic activity via estrogen receptors (ERs), but they may also affect estrogen synthesis and metabolism locally in breast, endometrial and ovarian tissues. Considering that accurate regulation of local hormone levels is crucial for normal physiology, it is not surprising that interference with hormonal synthesis and metabolism is associated with a wide variety of women's health problems, varying from altered menstrual cycle to hormone-dependent cancers. Yet, studies on phytoestrogens have mainly focused on ER-mediated effects of soy-derived phytoestrogens, with less attention paid to steroid synthesis and metabolism or other phytoestrogens. This review aims to evaluate the potential of phytoestrogens to modulate local estrogen levels and the implications for women's health. For that, an overview is provided of the effects of commonly used phytoestrogens, i.e. 8-prenylnaringenin, biochanin A, daidzein, genistein, naringenin, resveratrol and quercetin, on estrogen synthesizing and metabolizing enzymes in vitro. The potential implications for women's health are assessed by comparing the in vitro effect concentrations with blood concentrations that can be found after intake of these phytoestrogens. Based on this evaluation, it can be concluded that high-dose supplements with phytoestrogens might affect breast and endometrial health or fertility in women via the modulation of steroid hormone levels. However, more data regarding the tissue levels of phytoestrogens and effect data from dedicated, tissue-specific assays are needed for a better understanding of potential risks. At least until more certainty regarding the safety has been established, especially young women would better avoid using supplements containing high doses of phytoestrogens.

C-Jun NH2-Terminal Kinase and p38 Inhibition Suppresses Prostaglandin E2-Stimulated Aromatase and Estrogen Receptor Levels in Human Endometriosis

CONTEXT

Endometriosis is an estrogen-dependent disease. P38 and C-jun NH2-terminal kinase (JNK) inhibitors may have a therapeutic effect on endometriosis through regulation of prostaglandin E2 (PGE2)-induced estrogen metabolism.

OBJECTIVE

The objective of this study was to determine whether the activated MAPKs signaling pathway observed in human ectopic endometrial stromal cells (ESCs) from ovarian endometriomas influences levels of aromatase and estrogen receptor β (ERβ) protein regulated by PGE2. In turn, the effects of inhibiting MAPKs in the presence of PGE2 on estrogen production were investigated in vitro and in vivo.

RESULTS

Expression of aromatase and ERβ regulated by PGE2 were much higher in ESCs than eutopic ESCs from the same person. Activation of p38, JNK, ERK 1/2 and ERK 5 MAPKs by PGE2 were observed in ESCs, where PGE2-stimulated aromatase and ERβ expression mainly through p38 and JNK pathway. P38 and JNK inhibition or small interfering RNA knockdown blocked PGE2-induced aromatase and ERβ expression. PGE2 enhanced binding of downstream p38 and JNK transcription factors activating transcription factor-2 and c-Jun to aromatase and ERB promoter regions in ESCs. Moreover, treatment of endometriosis xenografts with inhibitors of p38 and JNK abrogated PGE2-amplified estradiol synthesis and xenograft growth.

CONCLUSIONS

PGE2 activates p38 and JNK signaling pathways, further stimulating c-Jun and activating transcription factor-2 binding to aromatase and ERB promoter regions with elevated estradiol production. Inhibition of JNK and P38 may be a potential method of treating human endometriosis.

Aromatase expression increases the survival and malignancy of estrogen receptor positive breast cancer cells

In postmenopausal women, local estrogen produced by adipose stromal cells in the breast is believed to support estrogen receptor alpha (ERα) positive breast cancer cell survival and growth. This raises the question of how the ERα positive metastatic breast cancer cells survive after they enter blood and lymph circulation, where estrogen level is very low in postmenopausal women. In this study, we show that the aromatase expression increased when ERα positive breast cancer cells were cultured in suspension. Furthermore, treatment with the aromatase substrate, testosterone, inhibited suspension culture-induced apoptosis whereas an aromatase inhibitor attenuated the effect of testosterone suggesting that suspended circulating ERα positive breast cancer cells may up-regulate intracrine estrogen activity for survival. Consistent with this notion, a moderate level of ectopic aromatase expression rendered a non-tumorigenic ERα positive breast cancer cell line not only tumorigenic but also metastatic in female nude mice without exogenous estrogen supplementation. The increased malignant phenotype was confirmed to be due to aromatase expression as the growth of orthotopic tumors regressed with systemic administration of an aromatase inhibitor. Thus, our study provides experimental evidence that aromatase plays an important role in the survival of metastatic ERα breast cancer cells by suppressing anoikis.

Non-canonical WNT5A is a potential regulator of granulosa cell function in cattle

The WNT family has been implicated in follicular development in rodents, however, the role of WNTs in the follicle of monovulatory species is poorly understood. The objective of this study was to determine the potential roles of WNTs in bovine granulosa cell function. Cells cultured in serum-free medium expressed mRNA encoding WNT2B, WNT5B and WNT5A. Levels of WNT5A, but not of WNT2B or WNT5B mRNA, were down-regulated by FSH. Addition of WNT5A to cultured cells suppressed FSH-stimulated estradiol and progesterone secretion, and levels of mRNA encoding the steroidogenic enzymes CYP19A1, CYP11A1 and the FSH receptor, but had no effect on cell proliferation or apoptosis. Immunoblot experiments showed that WNT5A reduced activation of CTNNB1 and stimulated phosphorylation of MAPK8 and JUN proteins. We conclude that WNT5A is a negative regulator of FSH-stimulated granulosa cell steroidogenesis, and that it acts by suppressing canonical WNT signaling activity and inducing the non-canonical MAPK8/JUN pathway.

Evidence for microRNA-mediated regulation of steroidogenesis by hypoxia

Environmental hypoxia can occur in both natural and occupational environments. Over the recent years, the ability of hypoxia to cause endocrine disruption via perturbations in steroid synthesis (steroidogenesis) has become increasingly clear. To further understand the molecular mechanism underlying hypoxia-induced endocrine disruption, the steroid-producing human cell line H295R was used to identify microRNAs (miRNAs) affecting steroidogenic gene expression under hypoxia. Hypoxic treatment of H295R cells resulted in the downregulation of seven steroidogenic genes and one of these, CYP19A1 (aromatase), was shown to be regulated by the transcription factor hypoxia-inducible factor-1 (HIF-1). Using bioinformatic and luciferase reporter analyses, miR-98 was identified to be a CYP19A1-targeting miRNA from a subset of HIF-1-inducible miRNAs. Gain- and loss-of-function analysis suggested that under hypoxia, the increased expression of miR-98 led to the downregulation of CYP19A1 mRNA and protein expression and that it may have contributed to a reduction in estradiol (E2) production. Intriguingly, luciferase reporter assays using deletion constructs of a proximal 5′-flanking region of miR-98 did not reveal a hypoxia-responsive element (HRE)-containing promoter. Overall, this study provided evidence for the role of miRNAs in regulating steroidogenesis and novel insights into the molecular mechanisms of hypoxia-induced endocrine disruption.

Profiling of luteal transcriptome during prostaglandin F2-alpha treatment in buffalo cows: analysis of signaling pathways associated with luteolysis

In several species including the buffalo cow, prostaglandin (PG) F2α is the key molecule responsible for regression of corpus luteum (CL). Experiments were carried out to characterize gene expression changes in the CL tissue at various time points after administration of luteolytic dose of PGF2α in buffalo cows. Circulating progesterone levels decreased within 1 h of PGF2α treatment and evidence of apoptosis was demonstrable at 18 h post treatment. Microarray analysis indicated expression changes in several of immediate early genes and transcription factors within 3 h of treatment. Also, changes in expression of genes associated with cell to cell signaling, cytokine signaling, steroidogenesis, PG synthesis and apoptosis were observed. Analysis of various components of LH/CGR signaling in CL tissues indicated decreased LH/CGR protein expression, pCREB levels and PKA activity post PGF2α treatment. The novel finding of this study is the down regulation of CYP19A1 gene expression accompanied by decrease in expression of E2 receptors and circulating and intra luteal E2 post PGF2α treatment. Mining of microarray data revealed several differentially expressed E2 responsive genes. Since CYP19A1 gene expression is low in the bovine CL, mining of microarray data of PGF2α-treated macaques, the species with high luteal CYP19A1 expression, showed good correlation between differentially expressed E2 responsive genes between both the species. Taken together, the results of this study suggest that PGF2α interferes with luteotrophic signaling, impairs intra-luteal E2 levels and regulates various signaling pathways before the effects on structural luteolysis are manifest.

JunD and JunB integrate prostaglandin E2 activation of breast cancer-associated proximal aromatase promoters

Aromatase is the key enzyme in estrogen biosynthesis. Normal breast adipose tissue expresses low levels of aromatase via the distal promoter I.4. Breast adipose tissue surrounding a tumor exhibits excessive aromatase expression controlled by proximal aromatase promoters I.3/II, leading to high local levels of estrogen and breast cancer progression. Prostaglandin E(2) (PGE(2)) secreted by malignant breast epithelial cells activates breast cancer-associated aromatase promoters I.3/II, but silences promoter I.4, in cultured human breast adipose fibroblasts (BAF). The c-Jun N-terminal kinase 1 and p38α mitogen activated protein kinases are necessary for PGE(2) activation of aromatase promoters I.3/II; thus, we examined the roles of downstream targets, c-Jun, JunB, JunD, and activating transcription factor 2, in PGE(2)-mediated regulation of aromatase expression in BAF. PGE(2) induced JunB and JunD protein expression through protein kinase A and protein kinase C, respectively. JunB or JunD knockdown by small interfering RNA markedly reduced PGE(2)-induced total aromatase mRNA level and enzyme activity via promoters I.3/II. JunB knockdown also abrogated JunD expression. JunB stimulated, whereas JunD inhibited, aromatase promoter I.4 activity. Activating transcription factor 2 knockdown did not affect promoter-specific or total aromatase mRNA levels. c-Jun knockdown increased promoter I.4-specific and PGE(2)-induced promoters I.3/II-specific aromatase mRNA levels, leading to enhanced PGE(2)-induced total aromatase mRNA level and enzyme activity. JunD, c-Jun, and JunB bound to a CRE(-211/-199) essential for PGE(2) induction of aromatase promoters I.3/II. Taken together, JunD and c-Jun repress aromatase promoter I.4. JunD mediates, whereas c-Jun modulates, PGE(2) activation of aromatase promoters I.3/II via CRE(-211/-199). JunB also activates aromatase promoters I.3/II by maintaining JunD expression. Targeting JunD may abolish aromatase expression selectively in breast cancer tissue.

BRCA1/BARD1 complex interacts with steroidogenic factor 1--A potential mechanism for regulation of aromatase expression by BRCA1

Germline mutations in BRCA1 predispose women to early onset of breast and ovarian cancers. Findings from previous studies support the notion that the tissue- and gender-specific tumor suppression function of BRCA1 is associated with its role in negative regulation of aromatase expression, the rate-limiting step in estrogen biosynthesis. The molecular mechanism of BRCA1 in regulating aromatase promoter activity remains to be elucidated. In this study, we demonstrate that, in an ovarian granulosa cell line KGN, steroidogenic factor 1 (SF-1) is required for aromatase PII promoter basal activity as well as the elevated aromatase expression mediated by BRCA1 knockdown. Furthermore, BRCA1 in KGN cells exists mainly as a heterodimer with BARD1. We provide evidence that the BRCA1/BARD1 complex interacts with SF-1 both in vivo and in vitro. However, the intrinsic ubiquitin E3 ligase activity of BRCA1/BARD1 does not appear to contribute to ubiquitynation of SF-1. We propose that the interaction between SF-1 and BRCA1/BARD1 may recruit BRCA1/BARD1 complex to the aromatase PII promoter for BRCA1/BARD1-mediate transcriptional repression.

cJun integrates calcium activity and tlx3 expression to regulate neurotransmitter specification

Neuronal differentiation is accomplished through cascades of intrinsic genetic factors initiated in neuronal progenitors by external gradients of morphogens. Activity was thought to be important only late in development, but recent evidence indicates that activity also regulates early neuronal differentiation. Activity in post-mitotic neurons prior to synapse formation can regulate phenotypic specification, including neurotransmitter choice, but the mechanisms are not clear. Here we identify a mechanism that links endogenous calcium spike activity with an intrinsic genetic pathway to specify neurotransmitter choice in neurons in the dorsal embryonic spinal cord of Xenopus tropicalis. Early activity modulates transcription of the GABAergic/glutamatergic selection gene tlx3 and requires a variant cAMP response element (CRE) in its promoter. The cJun transcription factor binds to this CRE site, modulates transcription, and regulates neurotransmitter phenotype through its transactivation domain. Calcium signals through cJun N-terminal phosphorylation, thus integrating activity-dependent and intrinsic neurotransmitter specification. This mechanism provides a basis for early activity to regulate genetic pathways at critical decision points, switching the phenotype of developing neurons.

Function and regulation of the glutathione peroxidase homologous gene GPXH/GPX5 in Chlamydomonas reinhardtii

When exposed to strong sunlight, photosynthetic organisms encounter photooxidative stress by the increased production of reactive oxygen species causing harmful damages to proteins and membranes. Consequently, a fast and specific induction of defense mechanisms is required to protect the organism from cell death. In Chlamydomonas reinhardtii, the glutathione peroxidase homologous gene GPXH/GPX5 was shown to be specifically upregulated by singlet oxygen formed during high light conditions presumably to prevent the accumulation of lipid hydroperoxides and membrane damage. We now showed that the GPXH protein is a thioredoxin-dependent peroxidase catalyzing the reduction of hydrogen peroxide and organic hydroperoxides.Furthermore, the GPXH gene seems to encode a dual-targeted protein, predicted to be localized both in the chloroplast and the cytoplasm, which is active with either plastidic TRXy or cytosolic TRXh1. Putative dual-targeting is achieved by alternative transcription and translation start sites expressed independently from either a TATA-box or an Initiator core promoter. Expression of both transcripts was upregulated by photooxidative stress even though with different strengths. The induction required the presence of the core promoter sequences and multiple upstream regulatory elements including a Sp1-like element and an earlier identified CRE/AP-1 homologous sequence. This element was further characterized by mutation analysis but could not be confirmed to be a consensus CRE or AP1 element. Instead, it rather seems to be another member of the large group of TGAC-transcription factor binding sites found to be involved in the response of different genes to oxidative stress.

GnRH stimulates expression of PACAP in the pituitary gonadotropes via both the PKA and PKC signaling systems

Recent studies have demonstrated a clear role for pituitary adenylate cyclase-activating polypeptide (PACAP) in the regulation of gonadotropin biosynthesis and secretion, both alone and in conjunction with GnRH. First defined as a hypothalamic releasing factor, PACAP subsequently has been identified in the gonadotrope subpopulation of the anterior pituitary gland, suggesting that PACAP may act as an autocrine-paracrine factor in this tissue. In initial studies, we determined that GnRH markedly stimulated endogenous PACAP mRNA levels and promoter-reporter activity in the mature gonadotrope cell line, LbetaT2. GnRH-stimulated rat PACAP promoter activity was blunted with deletion from position -915 to -402 and eliminated with further truncation to position -77 relative to the transcriptional start site. Site-directed mutagenesis demonstrated a functional requirement for a cAMP response element (CRE)-like site at position -205 and an activating protein-1 (AP-1)-like site at position -275, both of which bound CRE binding protein and AP-1 family members on EMSA. Treatment with pharmacological activators or inhibitors of second messenger signaling pathways implicated the protein kinase A, protein kinase C, and MAPK pathways in the GnRH response. In support of these in vitro data, we demonstrate that JunB binds to the rat PACAP gene promoter by chromatin immunoprecipitation assay and that small interfering RNA knockdown of JunB, cFos, and CRE binding protein factors blunts PACAP expression. In summary, these results further elucidate the complex functional interactions between PACAP and GnRH in the anterior pituitary. Specifically, these studies demonstrate that GnRH-stimulated PACAP gene expression is mediated via multiple signaling pathways acting on CRE/AP-1 sites in the proximal gene promoter. Because both PACAP and GnRH regulate gonadotropin biosynthesis and secretion, these results provide important insight into the critical fine tuning of gonadotrope function and, thereby, the maintenance of normal reproductive function.

Conditional deletion of beta-catenin mediated by Amhr2cre in mice causes female infertility

Follicle-stimulating hormone (FSH) regulation of aromatase gene expression in vitro requires the transcriptional coactivator beta-catenin. To ascertain the physiological significance of beta-catenin in granulosa cells during folliculogenesis, mice homozygous for floxed alleles of beta-catenin were intercrossed with Amhr2cre mice. Conditional deletion of beta-catenin in 8-wk-old females occurred in derivatives of the Müllerian duct, granulosa cells and, surprisingly, in brain, pituitary, heart, liver, and tail. Female mice deficient for beta-catenin were infertile, despite reaching puberty and ovulating at the expected age, indications of apparently normal ovarian function. In contrast, their oviducts were grossly distended, with fewer but healthy oocytes. In addition, their uteri lacked implantation sites. Together, these two phenotypes could explain the complete loss of fertility. Nevertheless, although the ovary appeared normal, with serum estradiol concentrations in the normal range, there was marked animal-to-animal variation of mRNAs encoding beta-catenin and aromatase. Similarly, inhibin-alpha and luteinizing hormone receptor mRNAs varied considerably in whole ovaries, whereas pituitary Fshb mRNA was significantly reduced. Collectively, these features suggested cyclization recombination (CRE)-mediated recombination of beta-catenin may be unstable in proliferating granulosa cells, and therefore may mask the suspected steroidogenic requirement for beta-catenin. We tested this possibility by transducing primary cultures of granulosa cells from mice homozygous for floxed alleles of beta-catenin with a CRE-expressing adenovirus. Reduction of beta-catenin significantly compromised FSH stimulation of aromatase mRNA and subsequent production of estradiol. Collectively, these data suggest that FSH regulation of steroidogenesis requires beta-catenin, a role that remains hidden when tested through Amhr2cre-mediated recombination in vivo.

Atrazine-induced changes in aromatase activity in estrogen sensitive target tissues

Atrazine (ATR) is a pesticide used widely throughout North America. Although not directly estrogenic, ATR treatment has been shown to increase aromatase activity in tumor cell lines. Thus, it is suggested that ATR can increase local tissue estrogen levels in estrogen sensitive target tissues through increased aromatase activity. Therefore the effect of ATR on aromatase activity was measured in human granulosa-lutein cell cultures, cells that abundantly express aromatase, and endometrial stromal cell (ESC) cultures, cells that do not express aromatase. Aromatase activity was quantified by the tritiated water method and the specificity of the assay was confirmed by co-incubation with 4-hydroxyandrostenedione, an irreversible inhibitor of the catalytic activity of aromatase. Aromatase activity in ATR treated (1-10 microm) granulosa-lutein cells was increased more than 2-fold compared with control cultures. There were no treatment related changes in cellular protein and thus it is suggested that the ATR-induced change in aromatase activity was not due to an increase in cell number. ATR-treatment had no effect on ESC aromatase activity at any concentration tested. Similarly, there was no effect of ATR treatment on human recombinant aromatase activity in our cell-free test system. Therefore it is concluded that microm concentrations of ATR can increase aromatase activity of human granulosa cells but not ESC and this effect is not elicited at the enzyme level.

Caffeine induction of Cyp6a2 and Cyp6a8 genes of Drosophila melanogaster is modulated by cAMP and D-JUN protein levels

Cytochrome P450 monooxygenases or CYPs, a family of endobiotics and xenobiotics metabolizing enzymes, are found in all organisms. We reported earlier that the promoters of Drosophila Cyp6a2 and Cyp6a8 genes are induced by caffeine. Since caffeine antagonizes adenosine receptor (AdoR) and inhibits cAMP phosphodiesterase (PDE), we used luciferase reporter gene to examine whether in SL-2 cells and adult Drosophila, induction of the two Cyp6 genes is mediated via AdoR and/or PDE pathway. Results showed that AdoR is not involved because AdoR agonists or antagonists do not affect the Cyp6 promoter activities. However, inhibition of PDE by specific inhibitors including caffeine causes induction of both Cyp6 gene promoters. We also found that flies mutant for dunce gene coding for cAMP-PDE, have higher Cyp6a8 promoter activity than the wild-type flies. We demonstrate that caffeine treatment increases intracellular cAMP levels, and cAMP treatment induces the Cyp6 gene promoters. Since both Cyp6 genes have multiple sites for JUN transcription factors, which generally play a positive role in cAMP pathway, effect of Drosophila jun (D-jun) on the Cyp6a8 promoter activity was examined. Results showed that the expression of D-jun sense plasmid causes downregulation rather than activation of the Cyp6a8 promoter. Conversely, expression of antisense plasmid increased the promoter activity. Interestingly, caffeine treatment decreased the D-JUN protein level in SL-2 cells as well as in adult flies. These results suggest that D-jun acts as a negative regulator, and caffeine induction of Cyp6a8 and Cyp6a2 genes is mediated by the upregulation of cAMP pathway and downregulation of the D-JUN protein level.

Aromatase expression in the ovary: hormonal and molecular regulation

Estrogens are synthesized by the aromatase enzyme encoded by the Cyp19a1 gene, which contains an unusually large regulatory region. In most mammals, aromatase expression is under the control of two distinct promoters a gonad- and a brain-specific promoter. In humans, this gene contains 10 tissue-specific promoters that are alternatively used in various cell types and tumors. Each promoter is regulated by a distinct set of regulatory sequences and transcription factors that bind to these specific sequences. The cAMP/PKA/CREB pathway is considered to be the primary signaling cascade through which the gonad Cyp19 promoter is regulated. Very interestingly, in rat luteal cells, the proximal promoter is not controlled in a cAMP dependent manner. Strikingly, these cells express aromatase at high levels similar to those found in preovulatory follicles, suggesting that alternative and powerful mechanisms control aromatase expression in luteal cells and that the rat corpus luteum represents an important paradigm for understanding alternative controls of the aromatase gene. Here, the molecular and cellular mechanisms controlling the expression of the aromatase gene in granulosa and luteal cells are discussed.

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.

Prostaglandin E(2) induces breast cancer related aromatase promoters via activation of p38 and c-Jun NH(2)-terminal kinase in adipose fibroblasts

Aromatase is the key enzyme for estrogen biosynthesis. A distal promoter, PI.4, maintains baseline levels of aromatase in normal breast adipose tissue. In contrast, malignant breast epithelial cells secrete prostaglandin E(2) (PGE(2)), which stimulates aromatase expression via proximal promoters PI.3/PII in a cyclic AMP (cAMP)- and protein kinase C (PKC)-dependent manner in adjacent breast adipose fibroblasts (BAF), leading to increased local concentrations of estrogen. Although an effective treatment for breast cancer, aromatase inhibitors indiscriminately abolish estrogen synthesis in all tissues, causing major side effects. To identify drug targets to selectively block aromatase and estrogen production in breast cancer, we investigated PGE(2)-stimulated signaling pathways essential for aromatase induction downstream of cAMP and PKC in human BAFs. Here, we show that PGE(2) or its surrogate hormonal mixture dibutyryl cAMP (Bt(2)cAMP) + phorbol diacetate (PDA) stimulated the p38, c-jun NH(2)-terminal kinase (JNK)-1, and extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase pathways. Inhibition or small interfering RNA-mediated knockdown of p38 or JNK1, but not ERK, inhibited PGE(2)- or Bt(2)cAMP + PDA-induced aromatase activity and expression via PI.3/PII. Conversely, overexpression of wild-type p38alpha or JNK1 enhanced PGE(2)-stimulated aromatase expression via PII. PGE(2) or Bt(2)cAMP + PDA stimulated c-Jun and activating transcription factor-2 (ATF2) phosphorylation and binding to the PI.3/PII region. Specific activation of protein kinase A (PKA) or EPAC with cAMP analogues stimulated p38 and JNK1; however, only PKA-activating cAMP analogues induced aromatase expression. The PKC activator PDA effectively stimulated p38 and JNK1 phosphorylation but not aromatase expression. Taken together, PGE(2) activation of p38 and JNK1 via PKA and PKC is necessary for aromatase induction in BAFs, and p38 and JNK1 are potential new drug targets for tissue-specific ablation of aromatase expression in breast cancer.

Mono-(2-ethylhexyl) phthalate (MEHP) induces nuclear receptor 4A subfamily in NCI-H295R cells: a possible mechanism of aromatase suppression by MEHP

Phthalate esters are widely used as plasticizers for polyvinylchloride and are suspected of functioning as endocrine disrupters. Di-(2-ethylhexyl) phthalate (DEHP), the most important phthalate ester in commercial use, has been reported to act as a rodent reproductive toxicant. In the present study, we investigated the effects of phthalate esters on aromatase (CYP19) activity and on its gene expression in a human adrenocortical carcinoma cell line, NCI-H295R. Mono-(2-ethylhexyl) phthalate (MEHP), a principle metabolite of DEHP, dose-dependently suppressed aromatase activity and its transcription level. Furthermore, MEHP rapidly and transiently induced transcription of the genes which encode nuclear receptor 4A subfamily members (Nur77, Nurr1 and NOR-1), and up-regulated Nur77 promoter activation and Nur77 protein expression in the cells. MEHP-induced Nur77 transcription was inhibited by bisindolylmaleimide I (protein kinase C inhibitor) and wortmannin (phosphoinositide 3-kinase inhibitor). Finally, ectopic expression of Nur77 markedly suppressed forskolin-induced transcriptional activation of promoters I.3 and II of the CYP19 gene. These results suggest that the suppression of aromatase activity and its transcription level by MEHP exposure to NCI-H295R cells was regulated through the rapid and transient expression of Nur77 gene.

Nuclear factor-kappab (NF-kappaB): an unsuspected major culprit in the pathogenesis of endometriosis that is still at large?

Endometriosis, defined as the ectopic presence of endometrial glandular and stromal cells outside the uterine cavity, is a common benign gynecological disorder with an enigmatic pathogenesis. Many genes and gene products have been reported to be altered in endometriosis, yet some of them may not be major culprits but merely unwitting accomplices or even innocent bystanders. Therefore, the identification and apprehension of major culprits in the pathogenesis of endometriosis are crucial to the understanding of the pathogenesis and would help to develop better therapeutics for endometriosis. Although so far NF-kappaB only has left few traces of incriminating fingerprints, several lines of investigation suggest that NF-kappaB, a pivotal pro-inflammatory transcription factor, could promote and maintain endometriosis. Various inflammatory agents, growth factors, and oxidative stress activate NF-kappaB. NF-kappaB proteins themselves and proteins regulated by them have been linked to cellular transformation, proliferation, apoptosis, angiogenesis, and invasion. Interestingly, all existing and nearly all investigational medications for endometriosis appear to act through suppression of NF-kappaB activation. In endometriotic cells, NF-kappaB appears to be constitutively activated, and suppression of NF-kappaB activity by NF-kappaB inhibitors or proteasome inhibitors suppresses proliferation in vitro. Viewing NF-kappaB as a major culprit, an autoregulatory loop model can be postulated, which is consistent with existing data and, more importantly, can explain several puzzling phenomena that are otherwise difficult to interpret based on prevailing theories. This view has immediate and important implications for novel ways to treat endometriosis. Further research is warranted to precisely delineate the roles of NF-kappaB in the pathogenesis of endometriosis and to indict and convict its aiders and abettors.

Follicle-stimulating hormone/cAMP regulation of aromatase gene expression requires beta-catenin

Estrogens profoundly influence the physiology and pathology of reproductive and other tissues. Consequently, emphasis has been placed on delineating the mechanisms underlying regulation of estrogen levels. Circulating levels of estradiol in women are controlled by follicle-stimulating hormone (FSH), which regulates transcription of the aromatase gene (CYP19A1) in ovarian granulosa cells. Previous studies have focused on two downstream effectors of the FSH signal, cAMP and the orphan nuclear receptor steroidogenic factor-1 (NR5A1). In this report, we present evidence for beta-catenin (CTNNB1) as an essential transcriptional regulator of CYP19A1. FSH induction of select steroidogenic enzyme mRNAs, including Cyp19a1, is enhanced by beta-catenin. Additionally, beta-catenin is present in transcription complexes assembled on the endogenous gonad-specific CYP19A1 promoter, as evidenced by chromatin immunoprecipitation assays. Transient expression and RNAi studies demonstrate that FSH- and cAMP-dependent regulation of this promoter is sensitive to alterations in the level of beta-catenin. The stimulatory effect of beta-catenin is mediated through functional interactions with steroidogenic factor-1 that involve four acidic residues within its ligand-binding domain, mutation of which attenuates FSH/cAMP-induced Cyp19a1 mRNA accumulation. Together, these data demonstrate that beta-catenin is essential for FSH/cAMP-regulated gene expression in the ovary, identifying a central and previously unappreciated role for beta-catenin in estrogen biosynthesis, and a potential broader role in other aspects of follicular maturation.

Protein kinase C-theta-mediated signals enhance CD4+ T cell survival by up-regulating Bcl-xL

Productive engagement of TCR results in delivering signals required for T cell proliferation as well as T cell survival. Blocking TCR-mediated survival signals, T cells undergo apoptosis instead of proliferation upon TCR stimulation. During the activation process, T cells produce IL-2, which acts as an extrinsic survival factor. In addition, TCR stimulation results in up-regulation of Bcl-xL to enhance T cell survival intrinsically. We show in this study that protein kinase C (PKC)-theta is required for enhancing the survival of activated CD4+ T cells by up-regulating Bcl-xL. In response to TCR stimulation, CD4+ PKC-theta-/- T cells failed to up-regulate Bcl-xL, and underwent accelerated apoptosis via a caspase- and mitochondria-dependent pathway. Similar to PKC-theta-deficient primary CD4+ T cells, small interfering RNA-mediated knockdown of PKC-theta in Jurkat cells also resulted in apoptosis upon TCR stimulation. Forced expression of Bcl-xL was sufficient to inhibit apoptosis observed in PKC-theta knockdown cells. Furthermore, ectopic expression of PKC-theta stimulated a reporter gene driven by a mouse Bcl-xL promoter. Whereas an inactive form of PKC-theta or knockdown of endogenous PKC-theta led to inhibition of Bcl-xL reporter. PKC-theta-mediated activation of Bcl-xL reporter was inhibited by dominant-negative IkappaB kinase beta or dominant-negative AP-1. Thus, the PKC-theta-mediated signals may function not only in the initial activation of naive CD4+ T cells, but also in their survival during T cell activation by regulating Bcl-xL levels through NF-kappaB and AP-1 pathways.

A Case of Virilizing Brenner Tumor in a Postmenopausal Woman With Stromal Androgenic Activity

Although there are several reports of Brenner tumor showing estrogen activities, it is an extremely rare cause of androgen excess leading to virilism, and the source or mechanism of its androgen production is also unknown at present. A 74-year-old woman presented with lower abdominal pain and increased facial hair growth of 6-month duration. Bilateral ovarian tumors were detected, and her serum testosterone (1.7 ng/mL) and estradiol (75 pg/mL) levels were elevated. Bilateral salpingo-oophorectomy was performed. The ovarian tumors were diagnosed as benign Brenner tumor associated with fibrothecoma-like and luteinized stromal cells. Postoperatively, the serum testosterone and estradiol levels decreased. Immunohistochemically, fibrothecoma-like stromal cells were positive for cytochrome P-450 aromatase, which catalyzes the conversion from androgen to estrogen, and negative for c-Jun protein, which has recently reported to attenuate estrogen biosynthesis by directly down-regulating transcription of the aromatase gene. On the other hand, luteinized stromal cells were negative for cytochrome P-450 aromatase and positive for c-Jun protein. It is suggested that androgen is produced mainly in the luteinized stromal cells, because androgen is not converted to estrogen caused by suppression of aromatase biosynthesis by c-Jun.

Regulation of cAMP-induced arylalkylamine N-acetyltransferase, Period1, and MKP-1 gene expression by mitogen-activated protein kinases in the rat pineal gland

In rodent pineal glands, sympathetic innervation, which leads to norepinephrine release, is a key process in the circadian regulation of physiology and certain gene expressions. It has been shown that gene expression of the rate-limiting enzyme in the melatonin synthesis arylalkylamine N-acetyltransferase (Aa-Nat), circadian clock gene Period1, and mitogen-activated protein kinase (MAPK) phosphtase-1 (MKP-1), is controlled mainly by a norepinephrine-beta-adrenergic receptor-cAMP signaling cascade in the rat pineal gland. To further dissect the signaling cascades that regulate those gene expressions, we examined whether MAPKs are involved in cAMP-induced gene expression. Western blot and immunohistochemical analyses showed that one of the three MAPKs, c-Jun N-terminal kinase (JNK), was expressed in the pineal, and was phosphorylated by cAMP analogue stimulation with a peak 20 min after start of the stimulation, in vitro. A specific JNK inhibitor SP600125 (Anthra[1,9-cd]pyrazol-6(2H)-one1,9-pyrazoloanthrone), but not its negative control (N1-Methyl-1,9-pyrazoloanthrone), significantly reduced cAMP-stimulated Aa-Nat, Period1, and MKP-1 mRNA levels. Although another MAPK, p38(MAPK), has also been shown to be activated by cAMP stimulation, a p38(MAPK) inhibitor, SB203580 (4-(4-Fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole, HCl), showed no effect on cAMP-induced Aa-Nat and Period1 mRNA levels; whereas SB203580, but not its negative analogue SB202474 (4-Ethyl-2(p-methoxyphenyl)-5-(4'-pyridyl)-IH-imidazole, DiHCl), significantly reduced cAMP-induced MKP-1 mRNA levels. Taken together, our data suggest that cAMP-induced Aa-Nat and Period1 are likely to be mediated by activation of JNK, whereas MKP-1 may be mediated by both p38(MAPK) and JNK activations.

Modulation of aromatase expression by BRCA1: a possible link to tissue-specific tumor suppression

Mutations in BRCA1 increase risks of familial breast and ovarian cancers, particularly among premenopausal women. While BRCA1 plays an active role in DNA repair, this function alone may not be sufficient to explain why BRCA1-associated tumors predominantly occur in estrogen-responsive tissues. Aromatase is the rate-limiting enzyme in estrogen biosynthesis and a key target in breast cancer treatment. Aromatase expression in ovarian granulosa cells dictates levels of circulating estrogen in premenopausal women, and its aberrant overexpression in breast adipose tissues promotes breast cancer growth. Here, we show that BRCA1 modulates aromatase expression in ovarian granulosa cells and primary preadipocytes. The cyclic AMP-dependent expression of aromatase in ovarian granulosa cells is inversely correlated with the protein level of BRCA1. Importantly, transient knockdown of BRCA1 enhances aromatase expression in both ovarian granulosa cells and primary preadipocytes. We propose that BRCA1 deficiency in epithelial and certain nonepithelial cells may result in combined effects of aberrant estrogen biosynthesis and compromised DNA repair capability, which in turn may lead to specific cancers in the breast and ovary.