Nuclear Receptor Gene Expression Research Articles

Impact of chromafenozide on the expression of Halloween gene and nuclear receptor gene in Tetranychus cinnabarinus (Boisduval)

AbstractTetranychus cinnabarinus (Boisduval), a worldwide acarine pest, has garnered significant attention in recent studies, particularly regarding the role of ecdysteroids. Ecdysteroids (moulting hormone) played key roles in regulating the important physiological processes of arthropods, such as ecdysis, metamorphosis reproduction and immunity. However, the underlying mechanisms of ecdysteroid biosynthesis and signalling have not been elucidated in T. cinnabarinus. Therefore, in this study, we utilized RACE technology in conjunction with RT‐PCR to obtain the complete sequence of three Halloween genes disembodied (dib), shadow (sad), shade (shd) and ecdysone receptor (EcR). Moreover, we analysed the expression level of these target genes in T. cinnabarinus, which was found to be expressed at all developmental stages. When using sublethal concentration of chromafenozide for bioassay on nymph of T. cinnabarinus, as the concentration increased, the ecdysis rate, mortality and ecdysteroid content were increased, and the moulting duration was decreased. We also characterized the expression on nymph of T. cinnabarinus after treatment with sublethal concentrations of chromafenozide, which were up‐regulated. Based on these findings, we concluded that the treatment of sublethal chromafenozide enhanced Halloween gene and nuclear receptor gene expression, aided in the investigation of the molecular regulatory mechanism for moulting of T. cinnabarinus, and provided a theoretical basis for new agents.

Nuclear receptor gene expression during early gametogenesis in sea urchin Mesocentrotus nudus gonads

Nuclear receptor gene expression during early gametogenesis in sea urchin Mesocentrotus nudus gonads

The organotin triphenyltin disrupts cholesterol signaling in mammalian ovarian steroidogenic cells through a combination of LXR and RXR modulation

Organotins, a chemical family with over 30 congeners to which humans are directly exposed to through food consumption, are a chemical class widely used as stabilizers in polyvinyl chloride, and biocides in antifouling products. Aside from tributyltin (TBT), toxicological information on other organotin congeners, such as triphenyltin (TPT), remains scarce. Our previous work has demonstrated that TBT can interfere with cholesterol trafficking in steroidogenic cells. Given their structural similarities, we hypothesized that TPT, similar to TBT, disrupts intracellular cholesterol transport and impairs steroidogenesis in ovarian theca cells. To test this, human and ovine primary ovarian theca cells were isolated, purified and exposed to TPT at environmentally relevant doses (1 or 10 ng/ml) in pre-luteinized (48 h exposure) or luteinizing cells (72 h exposure). Intracellular cholesterol levels, progesterone, and testosterone secretion and gene expression of nuclear receptors, cholesterol transporters, and steroidogenic enzymes were evaluated. In ovine cells, TPT upregulated StAR, ABCA1, and SREBF1 mRNA and ABCA1 protein in both pre-luteinized and luteinized stages. TPT did not alter intracellular cholesterol or testosterone synthesis, but upregulated progesterone production. Inhibitor and shRNA knockdown approaches were then used to evaluate the role of retinoid X receptor (RXR) and liver X receptor (LXR) on TPT's effects. TPT upregulated ABCA1 and StAR expression was blocked by both LXR and RXR antagonists. TPT's effect on ABCA1 expression was reduced in LXRβ and RXRβ knockdown theca cells. Similar findings were obtained with primary human theca cells. No synergistic effect of TBT and TPT was observed. In conclusion, at an environmentally relevant dose, TPT upregulates theca cell cholesterol transporter ABCA1 expression via RXR and LXR pathways. Similar effects of TPT on human and sheep theca cells supports its conserved mechanism across mammalian theca cells.

Comparison of the Toxicological Effects of Pesticides in Non-Tumorigenic MCF-12A and Tumorigenic MCF-7 Human Breast Cells.

Humans are exposed to residues of organophosphate and neonicotinoid pesticides, commonly used in agriculture. Children are particularly vulnerable and, among possible adverse outcomes, the increased incidence of premature mammary gland development (thelarche) has raised concern. We evaluated the toxicological effects of chlorpyrifos (CPF), imidacloprid (IMI) and glyphosate (GLY) at exposure concentrations occurring in children on the tumorigenic MCF-7 and non-tumorigenic MCF-12A breast cell lines, as representative of the target organ model, assessing cytotoxicity, apoptosis, necrosis, intracellular reactive oxygen species (ROS) and ATP levels, 17β-estradiol secretion and gene expression of nuclear receptors involved in mammary gland development. The pesticides decreased cell vitality in MCF-7 and cell proliferation in MCF-12A cells. ATP levels were decreased in MCF-7 cells by pesticides and apoptosis was increased in MCF-12A cells only by GLY (2.3 nM). ROS production was decreased by pesticides in both cell lines, except IMI (1.6 nM) in MCF-7 cells. Endocrine disrupting activity was highlighted by induction of 17β-estradiol secretion and modulation of the gene expression of estrogen alpha and beta, progesterone, androgen, and aryl hydrocarbon receptors in both cell lines. The use of MCF-7 and MCF-12A cells highlighted dissimilar modes of action of each pesticide at low human relevant concentrations.

Pan-cancer analyses of human nuclear receptors reveal transcriptome diversity and prognostic value across cancer types

The human nuclear receptor (NR) superfamily comprises 48 ligand-dependent transcription factors that play regulatory roles in physiology and pathophysiology. In cancer, NRs have long served as predictors of disease stratification, treatment response, and clinical outcome. The Cancer Genome Atlas (TCGA) Pan-Cancer project provides a wealth of genetic data for a large number of human cancer types. Here, we examined NR transcriptional activity in 8,526 patient samples from 33 TCGA ‘Pan-Cancer’ diseases and 11 ‘Pan-Cancer’ organ systems using RNA sequencing data. The web-based Kaplan-Meier (KM) plotter tool was then used to evaluate the prognostic potential of NR gene expression in 21/33 cancer types. Although, most NRs were significantly underexpressed in cancer, NR expression (moderate to high expression levels) was predominantly restricted (46%) to specific tissues, particularly cancers representing gynecologic, urologic, and gastrointestinal ‘Pan-Cancer’ organ systems. Intriguingly, a relationship emerged between recurrent positive pairwise correlation of Class IV NRs in most cancers. NR expression was also revealed to play a profound effect on patient overall survival rates, with ≥5 prognostic NRs identified per cancer type. Taken together, these findings highlighted the complexity of NR transcriptional networks in cancer and identified novel therapeutic targets for specific cancer types.

Altered regulation of Nur77 nuclear receptor gene expression in the mesocorticolimbic regions of rat brain by amphetamine sensitization

The mechanisms underlying psychostimulant drug-induced sensitization include long-term cellular and molecular adaptations in dopaminergic circuits. Nur77, a member of the Nur family of transcription factors, is expressed in brain regions receiving dopamine inputs and plays a role in activity-induced synaptic modification. Here we evaluated changes in Nur77 mRNA levels in the medial prefrontal cortex (mPFC), dorsal striatum (Str) and nucleus accumbens (NAc) of rats receiving a repeated, sensitizing regimen of amphetamine (AMPH). Results were compared to two groups of controls – animals receiving repeated injections of saline (Rp-SAL) or with no treatment (CON). Two weeks after the last injection, the effect of an acute challenge dose of AMPH on Nur77 expression was evaluated using in-situ hybridization. Repeated AMPH treatment (Rp-AMPH) increased the levels of Nur77 mRNA in the mPFC, NAc core and shell regions. However, the effects of an acute injection of AMPH in each of the three groups of animals was distinct. Whereas an acute AMPH led to a significant increase of Nur77 in all brain regions of the CON animals, it had no significant effect in Rp-SAL animals. Interestingly, in acute AMPH-injected Rp-AMPH animals, Nur77 mRNA levels in the mPFC, Str and NAc regions were significantly lower compared to CON and Rp-SAL animals treated with acute AMPH. There was a positive correlation between AMPH -induced locomotor activity and Nur77 mRNA expression in CON animals; however, this relationship was absent in Rp-SAL and Rp-AMPH animals. The data suggest that Nur77 is a part of neuroadaptive changes caused by either mild stress of repeated injections as well as AMPH-sensitization and may play a role in abnormal behaviors induced by the drug.

Identification and expression of nuclear receptor genes and ecdysteroid titers during nymphal development in the spider Agelena silvatica

Ecdysteroids play an essential role in the regulation of the molting processes of arthropods. Nuclear receptors of the spider Agelena silvatica that showed high homology with other arthropods especially in the functional domains were identified, two isoforms of ecdysone receptor (AsEcRA, AsEcRB), retinoid X receptor (AsRXR) and two isoforms of E75 (AsE75A, AsE75D). AsEcR and AsRXR mRNA did not show major changes in expression but occurred throughout the third instar nymphal stage. AsE75DBD was low or non-existent at first then showed a sudden increase from D7 to D10. On the other hand, AsE75D was expressed in the first half and decreased from D6 to D10. Ecdysteroid titers showed a peak on D6 in A. silvatica third instar nymphs. LC–MS/MS analysis of the ecdysteroid peak revealed only 20-hydroxyecdysone (20E) was present. The 20E peak on D6 and increase in AsE75DBD from D7 is likely a result of ecdysteroids binding to the heterodimer formed with constant expression of the AsEcR and AsRXR receptors. These findings indicate the mechanisms regulating molting widely conserved in insects and other arthropods also similarly function in spiders.

Identification of novel genetic variants associated with membrane transporter, drug metabolizing enzyme and nuclear receptor gene expression in whole blood

Identification of novel genetic variants associated with membrane transporter, drug metabolizing enzyme and nuclear receptor gene expression in whole blood

Dynamics of nuclear receptor gene expression during Pacific oyster development.

BackgroundNuclear receptors are a highly conserved set of ligand binding transcription factors, with essential roles regulating aspects of vertebrate and invertebrate biology alike. Current understanding of nuclear receptor regulated gene expression in invertebrates remains sparse, limiting our ability to elucidate gene function and the conservation of developmental processes across phyla. Here, we studied nuclear receptor expression in the early life stages of the Pacific oyster, Crassostrea gigas, to identify at which specific key stages nuclear receptors are expressedResultsWe used quantitative RT-PCR to determine the expression profiles of 34 nuclear receptors, revealing three developmental key stages, during which nuclear receptor expression is dynamically regulated: embryogenesis, mid development from gastrulation to trochophore larva, and late larval development prior to metamorphosis. Clustering of nuclear receptor expression patterns demonstrated that transcriptional regulation was not directly related to gene phylogeny, suggesting closely related genes may have distinct functions. Expression of gene homologs of vertebrate retinoid receptors suggests participation in organogenesis and shell-formation, as they are highly expressed at the gastrulation and trochophore larval initial shell formation stages. The ecdysone receptor homolog showed high expression just before larval settlement, suggesting a potential role in metamorphosis.ConclusionThroughout early oyster development nuclear receptors exhibited highly dynamic expression profiles, which were not confined by gene phylogeny. These results provide fundamental information on the presence of nuclear receptors during key developmental stages, which aids elucidation of their function in the developmental process. This understanding is essential as ligand sensing nuclear receptors can be disrupted by xenobiotics, a mode of action through which anthropogenic environmental pollutants have been found to mediate effects.Electronic supplementary materialThe online version of this article (doi:10.1186/s12861-016-0129-6) contains supplementary material, which is available to authorized users.

BDE-47 causes developmental retardation with down-regulated expression profiles of ecdysteroid signaling pathway-involved nuclear receptor (NR) genes in the copepod Tigriopus japonicus

2,2′,4,4′-Tetrabromodiphenyl ether (BDE-47) is a persistent organic pollutant (POP) in marine environments. Despite its adverse effects (e.g. developmental retardation) in ecdysozoa, the effects of BDE-47 on transcription of ecdysteroid signaling pathway-involved-nuclear receptor (NR) genes and metamorphosis-related genes have not been examined in copepods. To examine the deleterious effect of BDE-47 on copepod molting and metamorphosis, BDE-47 was exposed to the harpacticoid copepod Tigriopus japonicus, followed by monitoring developmental retardation and transcriptional alteration of NR genes. The developmental rate was significantly inhibited (P<0.05) in response to BDE-47 and the agricultural insecticide gamma-hexachlorocyclohexane. Conversely, the ecdysteroid agonist ponasterone A (PoA) led to decreased molting and metamorphosis time (P<0.05) from the nauplius stage to the adult stage. In particular, expression profiles of all NR genes were the highest at naupliar stages 5–6 except for SVP, FTZ-F1, and HR96 genes. Nuclear receptor USP, HR96, and FTZ-F1 genes also showed significant sex differences (P<0.05) in gene expression levels over different developmental stages, indicating that these genes may be involved in vitellogenesis. NR gene expression patterns showed significant decreases (P<0.05) in response to BDE-47 exposure, implying that molting and metamorphosis retardation is likely associated with NR gene expression. In summary, BDE-47 leads to molting and metamorphosis retardation and suppresses transcription of NR genes. This information will be helpful in understanding the molting and metamorphosis delay mechanism in response to BDE-47 exposure.

Exposure to endocrine disrupters and nuclear receptor gene expression in infertile and fertile women from different Italian areas.

Within the PREVIENI project, infertile and fertile women were enrolled from metropolitan, urban and rural Italian areas. Blood/serum levels of several endocrine disrupters (EDs) (perfluorooctane sulfonate, PFOS; perfluorooctanoic acid, PFOA; di-2-ethylhexyl-phthalate, DEHP; mono-(2-ethylhexyl)-phthalate, MEHP; bisphenol A, BPA) were evaluated concurrently with nuclear receptors (NRs) gene expression levels (ERα, ERβ, AR, AhR, PPARγ, PXR) in peripheral blood mononuclear cells (PBMCs). Infertile women from the metropolitan area displayed significantly higher levels of: BPA compared to fertile women (14.9 vs. 0.5 ng/mL serum); BPA and MEHP compared to infertile women from urban and rural areas; enhanced expression levels of NRs, except PPARγ. Infertile women from urban and rural areas had PFOA levels significantly higher than those from metropolitan areas. Our study indicates the relevance of the living environment when investigating the exposure to EDs and the modulation of the NR panel in PBMC as a suitable biomarker of the effect, to assess the EDs impact on reproductive health.

Retinoic acid differentially affects in vitro proliferation, differentiation and mineralization of two fish bone-derived cell lines: Different gene expression of nuclear receptors and ECM proteins

Retinoic acid (RA), the main active metabolite of vitamin A, regulates vertebrate morphogenesis through signaling pathways not yet fully understood. Such process involves the specific activation of retinoic acid and retinoid X receptors (RARs and RXRs), which are nuclear receptors of the steroid/thyroid hormone receptor superfamily. Teleost fish are suitable models to study vertebrate development, such as skeletogenesis. Cell systems capable of in vitro mineralization have been developed for several fish species and may provide new insights into the specific cellular and molecular events related to vitamin A activity in bone, complementary to in vivo studies. This work aims at investigating the in vitro effects of RA (0.5 and 12.5μM) on proliferation, differentiation and extracellular matrix (ECM) mineralization of two gilthead seabream bone-derived cell lines (VSa13 and VSa16), and at identifying molecular targets of its action through gene expression analysis. RA induced phenotypic changes and cellular proliferation was inhibited in both cell lines in a cell type-dependent manner (36–59% in VSa13 and 17–46% in VSa16 cells). While RA stimulated mineral deposition in VSa13 cell cultures (50–62% stimulation), it inhibited the mineralization of extracellular matrix in VSa16 cells (11–57% inhibition). Expression of hormone receptor genes (rars and rxrs), and extracellular matrix-related genes such as matrix and bone Gla proteins (mgp and bglap), osteopontin (spp1) and type I collagen (col1a1) were differentially regulated upon exposure to RA in proliferating, differentiating and mineralizing cultures of VSa13 and VSa16 cells. Altogether, our results show: (i) RA affects proliferative and mineralogenic activities in two fish skeletal cell types and (ii) that during phenotype transitions, specific RA nuclear receptors and bone-related genes are differentially expressed in a cell type-dependent manner.

Tu2052 Acute Liver Torsion: A Rare Case of Abdominal Pain and Elevated Liver Transaminases

Background. Matrix proteins are essential in the HIV replication cycle. The HIV matrix protein p17 serves several functions in the viral replication cycle including the viral nuclear import at early stage of infection. In the late stage, p17 mediates the recruitment of the viral surface/transmembrane gp120/gp41 envelope protein complex into virions and targets Pr55Gag proteins to their assembly sites at the plasma membrane of infected cells. Members of the nuclear receptor superfamily exert their regulatory activity integrating regulatory effects exerted by nutrients with intermediate metabolism by positively and negatively regulating the expression of effector genes. We have previously demonstrated that HIV infection is associated with an altered expression of nuclear receptor transcriptome in human monocytes as well as that stimulation of these cells with p17 down-regulates the expression of FXR and PPARγ. Aims. To analyze the effect exerted by the HIV matrix protein p17 on nuclear receptor gene expression in HepG2 cells. Methods. Serum starved HepG2 cells were stimulated 18 hours with 2 μg/ml recombinant p17 protein. At the end of the stimulation total RNA was extracted, reverse-transcribed in cDNA and amplified using specific primers for 10 nuclear receptors. Relative mRNA expression of Fatty Acid Elongase (FAE) was also investigated. Results. HepG2 cells treated with the HIV matrix protein p17 expressed an altered pattern of nuclear receptors characterized by a profound down-regulation in the expression of PPARα, -β, -γ, RARα, RXR, LXRβ, FXR, SHP, PXR and GR. Of interest, the deregulated expression of these transcription factors was linked to reduced expression of the enzyme FAE which is involved in the elongation of fatty acids during their biosynthesis process (Figure). Conclusions. Altered expression of nuclear receptors mediating reciprocal regulation of lipid metabolism and immune function occurs in HepG2 cells under p17 administration. These data highlight a detrimental effects of HIV proteins in resetting lipid metabolism in liver cells. These data might explain detrimental effects of HIV-HCV coinfection on lipid metabolism.

Tu2051 The HIV Matrix Protein P17 Subverts the Nuclear Receptor Transcriptome in HEPG2 Cells

Background. Matrix proteins are essential in the HIV replication cycle. The HIV matrix protein p17 serves several functions in the viral replication cycle including the viral nuclear import at early stage of infection. In the late stage, p17 mediates the recruitment of the viral surface/transmembrane gp120/gp41 envelope protein complex into virions and targets Pr55Gag proteins to their assembly sites at the plasma membrane of infected cells. Members of the nuclear receptor superfamily exert their regulatory activity integrating regulatory effects exerted by nutrients with intermediate metabolism by positively and negatively regulating the expression of effector genes. We have previously demonstrated that HIV infection is associated with an altered expression of nuclear receptor transcriptome in human monocytes as well as that stimulation of these cells with p17 down-regulates the expression of FXR and PPARγ. Aims. To analyze the effect exerted by the HIV matrix protein p17 on nuclear receptor gene expression in HepG2 cells. Methods. Serum starved HepG2 cells were stimulated 18 hours with 2 μg/ml recombinant p17 protein. At the end of the stimulation total RNA was extracted, reverse-transcribed in cDNA and amplified using specific primers for 10 nuclear receptors. Relative mRNA expression of Fatty Acid Elongase (FAE) was also investigated. Results. HepG2 cells treated with the HIV matrix protein p17 expressed an altered pattern of nuclear receptors characterized by a profound down-regulation in the expression of PPARα, -β, -γ, RARα, RXR, LXRβ, FXR, SHP, PXR and GR. Of interest, the deregulated expression of these transcription factors was linked to reduced expression of the enzyme FAE which is involved in the elongation of fatty acids during their biosynthesis process (Figure). Conclusions. Altered expression of nuclear receptors mediating reciprocal regulation of lipid metabolism and immune function occurs in HepG2 cells under p17 administration. These data highlight a detrimental effects of HIV proteins in resetting lipid metabolism in liver cells. These data might explain detrimental effects of HIV-HCV coinfection on lipid metabolism.

The Impact of Endocrine Disruptors on Endocrine Targets

The potential effect of the so-called endocrine disruptors (EDCs) or xenoestrogens on human health and the proven effect on wildlife have got considerable attention in the scientific community. Endocrine disruption represents one of the most controversial environmental issues despite the fact that many substances, both natural and artificial, have been recognized to interfere with endocrine signaling pathways. Such interactions have been documented both in laboratory animal studies as well as in vitro. However, in humans there is limited evidence of endocrine disruption caused by EDCs. EDCs are a large group of persistent organic pollutants (POPs), such as polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and polybrominated ethers (PBDEs), chloronaphtalenes (PCNs), and bisphenol A (BPA), stable, lipophilic pollutants that affect fertility and cause serious reproductive problems. Xenoestrogens are synthetic compounds, but there are also numerous natural molecules in food that exhibit estrogen-mimetic activities. These natural molecules are mainly phytoestrogens isoflavones, and the most consumed are genistein and daidzein. Additionally, certain mushrooms or fungi can contain estrogen-like compounds called mycoestrogens. Xenoestrogens activities in oocyte, ovary, placenta, and mammary gland and in the consequent serious reproductive problems, including ototoxic action, lack of ovulation, premature ovarian failure (POF), or polycystic ovarian syndrome (PCOS) are discussed in the review E. Gregoraszczuk and A. Ptak “Endocrine-disrupting chemicals: some actions of POPs on female reproduction.” G. Kerdivel et al., in their paper “Assessment and molecular actions of endocrine-disrupting chemicals that interfere with estrogen receptor pathways” discuss different molecular actions of some of the major xenoestrogens found in food or the environment and summarize the current models used to evaluate environmental estrogens. This paper is accompanied by clinical study of Caserta et al. “Correlation of endocrine disrupting chemicals serum levels and white blood cells gene expression of nuclear receptors in a population of infertile women” compares the internal exposure to bisphenol A (BPA), perfluorooctane sulphonate (PFOS), perfluorooctanoic acid (PFOA), monoethylhexyl phthalate (MEHP), and di(2-ethylhexyl) phthalate (DEHP) in serum samples of 111 infertile women and 44 fertile women and analyses levels of gene expression of nuclear receptors (ERα, ERβ, AR, AhR, PXR, and PPARγ) as biomarkers of effective dose. Two of the papers deal with aspects of alkylphenols action as endocrine disruptors. The paper by B. Yi et al. “Association between endocrine disrupting phenols in colostrums and maternal and infant health” showed that most neonates who are exposed to BPA rather than NP or OP via colostrum are recommended continuous biomonitoring of the phenols to clarify their suspected health risk on neonates and pregnant or gestation mothers. Furthermore, A. Hejmej in their paper “Photoperiod-dependent effects of 4-tert-octylphenol on adherens and gap junction proteins in bank vole seminiferous tubules” evaluating in vivo and in vitro effects of 4-tert-octylphenol (OP) on the expression and distribution of adherens and gap junction proteins, N-cadherin, β-catenin, and connexin 43 (Cx43), in testes showed that long-term treatment with OP resulted in the reduction of junction proteins expressions independent of FSH indicating that OP acts directly on adherens and gap junction proteins in the testes. I. Woclawek-Potocka et al. in their paper “Diverse effects of phytoestrogens on the reproductive performance: cow as a model” review how exposure of soybean-derived phytoestrogens can have adverse effects on reproductive performance in female adults. Authors suggest that these findings should be specially taken into consideration when recommendations are made regarding dietary or therapeutic phytoestrogen intake in humans. Particularly that they are commonly recognized as therapeutic compounds. Polychlorinated naphthalenes (PCNs) are new player as endocrine disruptors. Data concerning their potency and action on ovarian function are scarce. Dr J. Barc et al. in their paper “Action of halowax 1051 on enzymes of phase I (CYP1A1) and phase II (SULT1A and COMT) metabolism in the pig ovary” describe local ovarian metabolism of PCNs in ovarian tissue and suggest that fast activation of phase I enzymes with simultaneous inhibition of phase II enzymes indicates that androgenic action of PCNs on follicular steroidogenesis may partially result from metabolite action occurring locally in ovarian follicles. To complete the issue, B. Ayala-Garcia et al. revise current knowledge about the epigenetic mechanisms that underlie the effects of EDs on phenotypic variability and plasticity to stress the value of using the information derived from experiments with EDs to unveil the mechanisms that underlie phenotypic variability and speciation through epigenetic phenotypic plasticity. Taking into account that in this special issue have been published review articles, research articles and clinical studies, we hope that the information published in this special issue enriches the knowledge of our readers and scholars interested in the influence of xenobiotics on human health. Ewa L. Gregoraszczuk Radmila Kovacevic

Correlation of Endocrine Disrupting Chemicals Serum Levels and White Blood Cells Gene Expression of Nuclear Receptors in a Population of Infertile Women

Significant evidence supports that many endocrine disrupting chemicals could affect female reproductive health. Aim of this study was to compare the internal exposure to bisphenol A (BPA), perfluorooctane sulphonate (PFOS), perfluorooctanoic acid (PFOA), monoethylhexyl phthalate (MEHP), and di(2-ethylhexyl) phthalate (DEHP) in serum samples of 111 infertile women and 44 fertile women. Levels of gene expression of nuclear receptors (ERα, ERβ, AR, AhR, PXR, and PPARγ) were also analyzed as biomarkers of effective dose. The percentage of women with BPA concentrations above the limit of detection was significantly higher in infertile women than in controls. No statistically significant difference was found with regard to PFOS, PFOA, MEHP and DEHP. Infertile patients showed gene expression levels of ERα, ERβ, AR, and PXR significantly higher than controls. In infertile women, a positive association was found between BPA and MEHP levels and ERα, ERβ, AR, AhR, and PXR expression. PFOS concentration positively correlated with AR and PXR expression. PFOA levels negatively correlated with AhR expression. No correlation was found between DEHP levels and all evaluated nuclear receptors. This study underlines the need to provide special attention to substances that are still widely present in the environment and to integrate exposure measurements with relevant indicators of biological effects.

ABC drug transporter and nuclear receptor expression in human cytotrophoblasts: Influence of spontaneous syncytialization and induction by glucocorticoids

ObjectivesABC transporters in the human placenta play a major role in protecting the fetus against potential toxic drugs. The glucocorticoid dexamethasone has been shown to induce ABCB1 expression in enterocytes and hepatocytes. However, in placental cells, little data exists either for dexamethasone, betamethasone or prednisone while these three glucocorticoids may be used during pregnancy. We investigated the modulation of placental ABC transporter and nuclear receptor expression by these drugs. MethodsCytotrophoblasts were isolated from normal full-term placentas. We first assessed the influence of spontaneous syncytialization on transporter and nuclear receptor gene expression by taking samples of cytotrophoblasts after 24, 48 and 72 h of cell culture (n = 7 placentas). Incubations were then conducted with dexamethasone (50 nM–1 μM), betamethasone (20–400 nM) and prednisone (50 nM–1 μM) versus no drug for 24 h (n = 6). mRNA expression was determined by qRT-PCR. ResultsInfluence of syncytialization was observed only for ABCB1, ABCC2 and ABCC5 gene expression between t = 24 and 48 h (p < 0.05). Therefore, the following induction studies were conducted between t = 48 h and 72 h. Dexamethasone and betamethasone significantly induced ABCB1 gene expression by around 4-fold (p < 0.01 and 0.001, respectively). In parallel, 100 nM betamethasone decreased the glucocorticoid receptor gene expression by 22% (p < 0.01). Prednisone showed no effect on transporter or receptor expression. ConclusionsThese results suggest that dexamethasone or betamethasone administration may decrease the maternal–fetal transfer of an associated treatment being ABCB1 substrate, which may be either protective or deleterious for the fetus depending on the treatment's therapeutic aim.

Ecdysone- and NO-Mediated Gene Regulation by Competing EcR/Usp and E75A Nuclear Receptors during Drosophila Development

The Drosophila ecdysone receptor (EcR/Usp) is thought to activate or repress gene transcription depending on the presence or absence, respectively, of the hormone ecdysone. Unexpectedly, we found an alternative mechanism at work in salivary glands during the ecdysone-dependent transition from larvae to pupae. In the absense of ecdysone, both ecdysone receptor subunits localize to the cytoplasm, and the heme-binding nuclear receptor E75A replaces EcR/Usp at common target sequences in several genes. During the larval-pupal transition, a switch from gene activation by EcR/Usp to gene repression by E75A is triggered by a decrease in ecdysone concentration and by direct repression of the EcR gene by E75A. Additional control is provided by developmentally timed modulation of E75A activity by NO, which inhibits recruitment of the corepressor SMRTER. These results suggest a mechanism for sequential modulation of gene expression during development by competing nuclear receptors and their effector molecules, ecdysone and NO.

Aging Is Associated With a Shift of Fatty Metabolism Toward Lipogenesis

The incidence of nonalcoholic fatty liver disease is steadily increasing among the elderly population. Lipid metabolism is transcriptionally controlled by the nuclear receptors retinoid acid receptor alpha, liver-X-receptor alpha, and peroxisome proliferator-activated receptor alpha and their target genes ABCA1, sterol regulatory element-binding protein-1c, and fatty acid synthase. Using senescence-accelerated prone mice (SAMP8), we addressed the question as to whether age-related increase of oxidative stress affects nuclear receptor gene expression. In contrast to SAMR1 control mice, young SAMP8 mice exhibit hepatic steatosis with increased hepatic cholesterol content, plasma triglyceride, and aspartate aminotransferase levels. This is accompanied by an increase of liver-X-receptor alpha and retinoid acid receptor alpha expression, whereas peroxisome proliferator-activated receptor alpha expression is found diminished. SAMP8 mice further reveal a lower expression of ABCA1 as well as of sterol regulatory element-binding protein-1c and higher expression of fatty acid synthase. The dysbalance between the nuclear receptors and their target genes most probably mediates hepatic steatosis and underlines the pathological relevance of nuclear receptor shift toward lipogenesis in fat metabolism of the elderly patient.

Differential Role of Toll-Interleukin 1 Receptor Domain-Containing Adaptor Protein in Toll-Like Receptor 2-Mediated Regulation of Gene Expression of Hepatic Cytokines and Drug-Metabolizing Enzymes

Pharmacological activities of drugs are impaired during inflammation because of reduced expression of hepatic drug-metabolizing enzyme genes (DMEs) and their regulatory nuclear receptors (NRs): pregnane X receptor (PXR), constitutive androstane receptor (CAR), and retinoid X receptor (RXRα). We have shown that a component of Gram-positive bacteria, lipoteichoic acid (LTA) induces proinflammatory cytokines and reduces gene expression of hepatic DMEs and NRs. LTA is a Toll-like receptor 2 (TLR2) ligand, which initiates signaling by recruitment of Toll-interleukin 1 receptor domain-containing adaptor protein (TIRAP) to the cytoplasmic TIR domain of TLR2. To determine the role of TIRAP in TLR2-mediated regulation of DME genes, TLR2(+/+), TLR2(-/-), TIRAP(+/+), and TIRAP(-/-) mice were given LTA injections. RNA levels of the DMEs (Cyp3a11, Cyp2b10, and sulfoaminotransferase), xenobiotic NRs (PXR and CAR), and nuclear protein levels of the central NR RXRα were reduced ∼ 50 to 60% in LTA-treated TLR2(+/+) but not in TLR2(-/-) mice. Induction of hepatic cytokines (interleukin-1β, tumor necrosis factor-α, and interleukin-6), c-Jun NH(2)-terminal kinase, and nuclear factor-κΒ was blocked in TLR2(-/-) mice. As expected, expression of hepatic DMEs and NRs was reduced by LTA in TIRAP(+/+) but not in TIRAP(-/-) mice. Of interest, cytokine RNA levels were induced in the livers of both the TIRAP(+/+) and TIRAP(-/-) mice, whereas LTA-mediated induction of serum cytokines was attenuated in TIRAP(-/-) mice. LTA-mediated down-regulation of DME genes was attenuated in hepatocytes from TLR2(-/-) or TIRAP(-/-) mice and in small interfering RNA-treated hepatocytes. Thus, the effect of TLR2 on DME genes in hepatocytes was mediated by TIRAP, whereas TIRAP was not involved in mediating the effects of TLR2 on cytokine expression in the liver.