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Epigenetic responses following maternal dietary exposure to physiologically relevant levels of bisphenol A.

ABSTRACT: Animal studies have linked perinatal bisphenol A (BPA) exposure to altered DNA methylation, but little attention is given to analyzing multiple physiologically relevant doses. Utilizing the viable yellow agouti (A(vy)) mouse, we examine the effects of developmental exposure through maternal diet to 50 ng BPA/kg (n = 14 litters), 50 ?g BPA/kg (n = 9 litters), or 50 mg BPA/kg (n = 13 litters) on global and candidate gene methylation at postnatal day 22. Global methylation analysis reveals hypermethylation in tail tissue of a/a and A(vy)/a offspring across all dose groups compared with controls (n = 11 litters; P < 0.02). Analysis of coat color phenotype replicates previous work showing that the distribution of 50 mg BPA/kg A(vy)/a offspring shifts toward yellow (P = 0.006) by decreasing DNA methylation in the retrotransposon upstream of the Agouti gene (P = 0.03). Maternal exposure to 50 ?g or 50 ng BPA/kg, however, results in altered coat color distributions in comparison with control (P = 0.04 and 0.02), but no DNA methylation effects at the Agouti gene are noted. DNA methylation at the CDK5 activator-binding protein (Cabp(IAP)) metastable epiallele shows hypermethylation in the 50 ?g BPA/kg offspring, compared with controls (P = 0.02). Comparison of exposed mouse liver BPA levels to human fetal liver BPA levels indicates that the three experimental exposures are physiologically relevant. Thus, perinatal BPA exposure affects offspring phenotype and epigenetic regulation across multiple doses, indicating the need to evaluate dose effects in human clinical and population studies.

SUBMITTER: Anderson OS

PROVIDER: S-EPMC3570056 | biostudies-literature | 2012 Jun

REPOSITORIES: biostudies-literature

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Epigenetic responses following maternal dietary exposure to physiologically relevant levels of bisphenol A.

Anderson Olivia S OS Nahar Muna S MS Faulk Christopher C Jones Tamara R TR Liao Chunyang C Kannan Kurunthachalam K Weinhouse Caren C Rozek Laura S LS Dolinoy Dana C DC

Environmental and molecular mutagenesis 20120329 5

Animal studies have linked perinatal bisphenol A (BPA) exposure to altered DNA methylation, but little attention is given to analyzing multiple physiologically relevant doses. Utilizing the viable yellow agouti (A(vy)) mouse, we examine the effects of developmental exposure through maternal diet to 50 ng BPA/kg (n = 14 litters), 50 μg BPA/kg (n = 9 litters), or 50 mg BPA/kg (n = 13 litters) on global and candidate gene methylation at postnatal day 22. Global methylation analysis reveals hypermet ...[more]

PMID: 22467340

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Project description:Background: Animal-based studies indicate that Bisphenol A (BPA) exposure is detrimental to reproductive health, but its impact on the earliest stages of germ cell development remain poorly defined. Objective: Using a murine in vitro model of early germ cell specification and differentiation, we sought to assess whether exposure to low levels of BPA prior to Primordial Germ Cell (PGC) formation alters their differentiation trajectory and unique molecular program. Methods: We used an established method of in vitro differentiation of mouse Embryonic Stem Cells (ESCs) into Epiblast-like Cells (EpiLCs) followed by PGC-Like Cells (PGCLCs) which together recapitulates defined stages of early germ cell development. Cellular consequences were determined using hemocytometer-based cell counting, fixation and intracellular staining followed by flow cytometry/FACS on cells exposed to increasing doses of BPA. We also generated RNA-seq libraries from RNA extracted from FACS-purified PGCLCs and performed transcriptome analysis using bioinformatics-based approaches, to interrogate and characterise gene expression changes resulting from BPA exposure. Results: Exposure of EpiLCs to BPA resulted in a dose-dependent increase in cell number, associated with an increase proportion of cells in S-phase as well as a reduced proportion undergoing apoptosis. Exposure also resulted in a greater proportion of EpiLCs showing signs of DNA damage. Remarkably, EpiLC exposure did not negatively impact PGC specification and resulted in dose-dependent increase in PGCLC proliferation. However, PGCLC transcriptome analysis revealed an aberrant program with significant deregulation of X-linked genes and retrotransposon expression. Differential gene expression analysis also revealed the deregulation of genes associated with lipid metabolism as well as deregulated expression of genes associated with later stages of gametogenesis. Conclusions: Our findings represent the first characterisation of the consequences of early BPA exposure on a model of PGC development, highlighting altered cell behaviour and underlying pathways and molecular processes.

Project description:BackgroundAnimal-based studies indicate that bisphenol A (BPA) exposure is detrimental to reproductive health, but its impact on the earliest stages of germ cell development remains poorly defined.ObjectivesUsing a murine in vitro model of early germ cell specification and differentiation, we sought to assess whether exposure to low levels of BPA prior to formation of primordial germ cells (PGCs) alters their differentiation trajectory and unique molecular program.MethodsWe used an established method of in vitro differentiation of mouse embryonic stem cells (ESCs) into epiblast-like cells (EpiLCs) followed by PGC-like cells (PGCLCs), which together recapitulate defined stages of early germ cell development. Cellular consequences were determined using hemocytometer-based cell counting, fixation, and intracellular staining, followed by flow cytometry/fluorescence-activated cell sorting (FACS) of cells exposed to increasing concentrations (range: 1 nM-10 μM) of BPA. To interrogate and characterize gene expression differences resulting from BPA exposure, we also generated RNA-seq libraries from RNA extracted from FACS-purified PGCLCs and performed transcriptome analysis using bioinformatics-based approaches.ResultsExposure of EpiLCs to BPA resulted in higher numbers of cells that were associated with a higher proportion of cells in S-phase as well as a lower proportion undergoing apoptosis; this difference occurred in a concentration-dependent manner. Exposure also resulted in a greater fraction of EpiLCs showing signs of DNA damage. Remarkably, EpiLC exposure did not negatively affect PGC specification and resulted in a concentration-dependent effect on PGCLC proliferation in XX but not XY cells. PGCLC transcriptome analysis revealed an aberrant program with significant deregulation of X-linked genes and retrotransposon expression. Differential gene expression analysis also revealed the deregulation of genes associated with lipid metabolism as well as deregulated expression of genes associated with later stages of gametogenesis.ConclusionsTo the best of our knowledge our findings represent the first characterization of the consequences of early BPA exposure on a model of mammalian PGC development, highlighting altered cell behavior, altered underlying pathways, and altered molecular processes. https://doi.org/10.1289/EHP8196.

Project description:BackgroundNano-titanium dioxide (nano-TiO2) is amongst the most widely utilized engineered nanomaterials (ENMs). However, little is known regarding the consequences maternal ENM inhalation exposure has on growing progeny during gestation. ENM inhalation exposure has been reported to decrease mitochondrial bioenergetics and cardiac function, though the mechanisms responsible are poorly understood. Reactive oxygen species (ROS) are increased as a result of ENM inhalation exposure, but it is unclear whether they impact fetal reprogramming. The purpose of this study was to determine whether maternal ENM inhalation exposure influences progeny cardiac development and epigenomic remodeling.ResultsPregnant FVB dams were exposed to nano-TiO2 aerosols with a mass concentration of 12.09 ± 0.26 mg/m3 starting at gestational day five (GD 5), for 6 h over 6 non-consecutive days. Aerosol size distribution measurements indicated an aerodynamic count median diameter (CMD) of 156 nm with a geometric standard deviation (GSD) of 1.70. Echocardiographic imaging was used to assess cardiac function in maternal, fetal (GD 15), and young adult (11 weeks) animals. Electron transport chain (ETC) complex activities, mitochondrial size, complexity, and respiration were evaluated, along with 5-methylcytosine, Dnmt1 protein expression, and Hif1α activity. Cardiac functional analyses revealed a 43% increase in left ventricular mass and 25% decrease in cardiac output (fetal), with an 18% decrease in fractional shortening (young adult). In fetal pups, hydrogen peroxide (H2O2) levels were significantly increased (~ 10 fold) with a subsequent decrease in expression of the antioxidant enzyme, phospholipid hydroperoxide glutathione peroxidase (GPx4). ETC complex activity IV was decreased by 68 and 46% in fetal and young adult cardiac mitochondria, respectively. DNA methylation was significantly increased in fetal pups following exposure, along with increased Hif1α activity and Dnmt1 protein expression. Mitochondrial ultrastructure, including increased size, was observed at both fetal and young adult stages following maternal exposure.ConclusionsMaternal inhalation exposure to nano-TiO2 results in adverse effects on cardiac function that are associated with increased H2O2 levels and dysregulation of the Hif1α/Dnmt1 regulatory axis in fetal offspring. Our findings suggest a distinct interplay between ROS and epigenetic remodeling that leads to sustained cardiac contractile dysfunction in growing and young adult offspring following maternal ENM inhalation exposure.

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Epigenetic responses following maternal dietary exposure to physiologically relevant levels of bisphenol A.

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Epigenetic responses following maternal dietary exposure to physiologically relevant levels of bisphenol A.

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