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Effect of the methoxychlor metabolite HPTE on the rat ovarian granulosa cell transcriptome in vitro.

ABSTRACT: Ovarian granulosa cells play a central role in steroidogenesis, which is critical for female reproduction. Follicle-stimulating hormone (FSH) promotes cyclic adenosine monophosphate (cAMP)-mediated 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 messenger RNA 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 microM HPTE in the presence or absence of either 3 ng FSH/ml or 1mM cAMP for 48 h. Total RNA was isolated for real-time quantitative PCR and 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- (approximately 670 genes) than in cAMP-stimulated cells (approximately 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.

SUBMITTER: Harvey CN

PROVIDER: S-EPMC2696328 | biostudies-literature | 2009 Jul

REPOSITORIES: biostudies-literature

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Effect of the methoxychlor metabolite HPTE on the rat ovarian granulosa cell transcriptome in vitro.

Harvey Craig N CN Esmail Mahmoud M Wang Qi Q Brooks Andrew I AI Zachow Rob R Uzumcu Mehmet M

Toxicological sciences : an official journal of the Society of Toxicology 20090504 1

Ovarian granulosa cells play a central role in steroidogenesis, which is critical for female reproduction. Follicle-stimulating hormone (FSH) promotes cyclic adenosine monophosphate (cAMP)-mediated 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 messenger RNA levels of steroidogenic pathway enzymes in rat granulosa cells. However, ...[more]

PMID: 19414516

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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).

Project description:BackgroundThe major function of the ovary is to produce oocytes for fertilisation. Oocytes mature in follicles surrounded by nurturing granulosa cells and all are enclosed by a basal lamina. During growth, granulosa cells replicate and a large fluid-filled cavity (the antrum) develops in the centre. Only follicles that have enlarged to over 10 mm can ovulate in cows. In mammals, the number of primordial follicles far exceeds the numbers that ever ovulate and atresia or regression of follicles is a mechanism to regulate the number of oocytes ovulated and to contribute to the timing of ovulation. To better understand the molecular basis of follicular atresia, we undertook transcriptome profiling of granulosa cells from healthy (n = 10) and atretic (n = 5) bovine follicles at early antral stages (< 5 mm).ResultsPrincipal Component Analysis (PCA) and hierarchical classification of the signal intensity plots for the arrays showed primary clustering into two groups, healthy and atretic. These analyses and size-frequency plots of coefficients of variation of signal intensities revealed that the healthy follicles were more heterogeneous. Examining the differentially-expressed genes the most significantly affected functions in atretic follicles were cell death, organ development, tissue development and embryonic development. The overall processes influenced by transcription factor gene TP53 were predicted to be activated, whereas those of MYC were inhibited on the basis of known interactions with the genes in our dataset. The top ranked canonical pathway contained signalling molecules common to various inflammatory/fibrotic pathways such as the transforming growth factor-β and tumour necrosis factor-α pathways. The two most significant networks also reflect this pattern of tissue remodelling/fibrosis gene expression. These networks also contain molecules which are present in the canonical pathways of hepatic fibrosis/hepatic stellate cell activation and transforming growth factor-β signalling and were up regulated.ConclusionsSmall healthy antral follicles, which have a number of growth outcomes, exhibit greater variability in gene expression, particularly in genes associated with cell division and other growth-related functions. Atresia, on the other hand, not only involves cell death but clearly is an active process similar to wound healing.

Dataset Information

Effect of the methoxychlor metabolite HPTE on the rat ovarian granulosa cell transcriptome in vitro.

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Effect of the methoxychlor metabolite HPTE on the rat ovarian granulosa cell transcriptome in vitro.

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