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Methoxychlor and its metabolite HPTE inhibit cAMP production and expression of estrogen receptors ? and ? in the rat granulosa cell in vitro.

ABSTRACT: The major metabolite of the estrogenic pesticide methoxychlor (MXC) HPTE is a stronger ESR1 agonist than MXC and acts also as an ESR2 antagonist. In granulosa cells (GCs), FSH stimulates estradiol via the second messenger cAMP. HPTE inhibits estradiol biosynthesis, and this effect is greater in FSH-treated GCs than in cAMP-treated GCs. Therefore; we examined the effect of MXC/HPTE on FSH-stimulated cAMP production in cultured GCs. To test involvement of ESR-signaling, we used the ESR1 and ESR2 antagonist ICI 182,780, ESR2 selective antagonist PHTPP, and ESR2 selective agonist DPN. ESR1 and ESR2 mRNA and protein levels were quantified. Both HPTE and MXC inhibited the FSH-induced cAMP production. ICI 182,780 and PHTPP mimicked the inhibitory action of HPTE. MXC/HPTE reduced FSH-stimulated Esr2 mRNA and protein to basal levels. MXC/HPTE also inhibited FSH-stimulated Esr1. The greater inhibition on FSH-stimulated GCs is likely due to reduced cAMP level that involves ESR-signaling, through ESR2.

SUBMITTER: Harvey CN

PROVIDER: S-EPMC4465425 | biostudies-literature | 2015 Jan

REPOSITORIES: biostudies-literature

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Methoxychlor and its metabolite HPTE inhibit cAMP production and expression of estrogen receptors α and β in the rat granulosa cell in vitro.

Harvey Craig N CN Chen Joseph C JC Bagnell Carol A CA Uzumcu Mehmet M

Reproductive toxicology (Elmsford, N.Y.) 20141227

The major metabolite of the estrogenic pesticide methoxychlor (MXC) HPTE is a stronger ESR1 agonist than MXC and acts also as an ESR2 antagonist. In granulosa cells (GCs), FSH stimulates estradiol via the second messenger cAMP. HPTE inhibits estradiol biosynthesis, and this effect is greater in FSH-treated GCs than in cAMP-treated GCs. Therefore; we examined the effect of MXC/HPTE on FSH-stimulated cAMP production in cultured GCs. To test involvement of ESR-signaling, we used the ESR1 and ESR2 a ...[more]

PMID: 25549949

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Project description:Ovarian granulosa cells play a central role in steroidogenesis, which is critical for female reproduction. Follicle-stimulating hormone (FSH) promotes cAMPâmediated signaling to regulate granulosa cell steroidogenesis. We have shown previously that 2, 2-bis-(p-hydroxyphenyl)-1, 1, 1-trichloroethane (HPTE) inhibits FSH- and dibutyryl cAMP-stimulated steroidogenesis, and affects the mRNA levels of steroidogenic pathway enzymes in rat granulosa cells. However, HPTE showed a differential effect in FSH- and cAMP-stimulated cells in that HPTE more completely blocked FSH- when compared to cAMP-driven steroidogenesis. The objective of this study was to analyze the effects of HPTE on global gene expression profiles in untreated granulosa cells and those challenged with FSH or cAMP. Granulosa cells from immature rats were cultured with 0, 1, 5, or 10 ÂµM HPTE in the presence and absence of either 3 ng FSH/ml or 1 mM cAMP for 48 h. Total RNA was isolated for microarray analysis using the GeneChip Rat Genome 230 2.0 and ArrayAssist Microarray Suite. An investigation of changes in gene expression across all HPTE treatments showed that HPTE altered more genes in FSH- (~670 genes) than in cAMP-stimulated cells (~366 genes). Analysis confirmed that HPTE more effectively inhibited FSH- than cAMP-induced steroid pathway gene expression and steroidogenesis. Furthermore, expression patterns of novel genes regulating signal transduction, transport, cell cycle, adhesion, differentiation, motility and growth, apoptosis, development, and metabolism were all altered by HPTE. This study further established that HPTE exerts differential effects within the granulosa cell steroidogenic pathway, and revealed that these effects include broader changes in gene expression. Experiment Overall Design: Ovaries were dissected from immature (21-27 days old), Sprague-Dawley rats and were placed into ice cold Hamâs F12 medium. Granulosa cells were isolated from ovaries free of fat pads and surrounding connective tissue by performing non-enzymatic needle puncture method . Following two washes by centrifugation at 1400rpm/250xg for 5 min at 4 CË, the cells were plated and cultured at approximately 3-4x105 viable cells/mL/well in DMEM/F-12 medium containing 5% FCS at 37 CË in 5% CO2 in a 24-well culture plate for 24 hours. The cells were then cultured in serum-free DMEM/F12 containing 0.1 Î¼M androstenedione as a substrate for aromatization into E2. Experiment Overall Design: Cells were treated in triplicate with increasing doses of HPTE (0, 1, 5, and 10 ÂµM) in the absence (basal) or presence of 3 ng FSH/ml or 1 mM cAMP for 48 h. The doses of FSH and cAMP were selected based on a dose-response curve that provided a maximum level of stimulation for E2 production (data not shown). Similar doses of HPTE were previously used (Zachow and Uzumcu, 2006). Cultures were terminated at 48 h following the addition of treatments. Experiment Overall Design: Cell lysate was collected for total RNA isolation for DNA microarray analysis. Total RNA were extracted using the RNeasy Mini Kit (Qiagen, Cat # 74106) followed by DNase I treatment. RNA qualities were assessed by electrophoresis using the Agilent Bioanalyzer 2100 and spectrophotometric analysis prior to cDNA synthesis. Forty nanograms of total RNA from each sample was used to generate a high fidelity cDNA for array hybridization using NuGen Ovation Biotin RNA Amplification and Labeling system (NuGen, Cat#2300-60). After fragmentation and biotin labeling, the samples were hybridized to Affymetrix Rat Genome 230 2.0 arrays. Washing and staining of all arrays were carried out in the Affymetrix fluidics module as per the manufacturerâs protocol. The detection and quantization of target hybridization was performed with an Affymetrix GeneChip Scanner. Data were assessed for array performance prior to analysis and analyzed using ArrayAssist (Stratagene).

Dataset Information

Methoxychlor and its metabolite HPTE inhibit cAMP production and expression of estrogen receptors ? and ? in the rat granulosa cell in vitro.

Publications

Methoxychlor and its metabolite HPTE inhibit cAMP production and expression of estrogen receptors α and β in the rat granulosa cell in vitro.

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