Endocrine disruptor-induced epimutagenesis in vitro: Insight into molecular mechanisms [EM-Seq]
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ABSTRACT: Endocrine disrupting chemicals (EDCs) such as bisphenol S (BPS) are xenobiotic compounds that can disrupt endocrine signaling following exposure due to steric similarities to endogenous hormones within the body. EDCs have been shown to induce disruptions in normal epigenetic programming (epimutations) that accompany dysregulation of normal gene expression patterns that appear to predispose disease states. Most interestingly, the prevalence of epimutations following exposure to many different EDCs often persists over multiple subsequent generations, even with no further exposure to the causative EDC. Many previous studies have described both the direct and prolonged effects of EDC exposure in animal models, but many questions remain about molecular mechanisms by which EDCs initially induce epimutations or contribute to the propagation of EDC-induced epimutations either within the exposed generation or to subsequent generations. Additional questions remain regarding the extent to which there may be differences in cell type-specific susceptibilities to various EDCs, and whether this susceptibility is correlative with expression of relevant hormone receptors and/or the location of relevant hormone response elements (HREs) in the genome. To address these questions, we exposed cultured mouse pluripotent (induced pluripotent stem [iPS]), somatic (Sertoli and granulosa), and germ (primordial germ cell like [PGCLCs]) cells to BPS and measured changes in DNA methylation levels at the epigenomic level and gene expression at the transcriptomic level. We found that there was indeed a difference in cell type-specific susceptibility to EDC-induced epimutagenesis and that this susceptibility correlated with differential expression of relevant hormone receptors and, in many cases, tended to generate epimutations near relevant HREs within the genome. Additionally, however, we also found that BPS can induce epimutations in a cell type that does not express relevant receptors and in genomic regions that do not contain relevant HREs, suggesting that both canonical and non-canonical signaling mechanisms can be disrupted by BPS exposure. Most interestingly, we found that when iPS cells were exposed to BPS and then induced to differentiate into PGCLCs, the prevalence of epimutations and differentially expressed genes (DEGs) initially induced in the iPSCs was largely retained in the resulting PGCLCs, however, >90% of the specific epimutations and DEGs were not conserved but were rather replaced by novel epimutations and DEGs following the iPSC to PGCLC transition. These results suggest a unique mechanism by which an EDC-induced epimutated state may be propagated transgenerationally following a single exposure to the causative EDC.
Project description:Endocrine disrupting chemicals (EDCs) such as bisphenol S (BPS) are xenobiotic compounds that can disrupt endocrine signaling following exposure due to steric similarities to endogenous hormones within the body. EDCs have been shown to induce disruptions in normal epigenetic programming (epimutations) that accompany dysregulation of normal gene expression patterns that appear to predispose disease states. Most interestingly, the prevalence of epimutations following exposure to many different EDCs often persists over multiple subsequent generations, even with no further exposure to the causative EDC. Many previous studies have described both the direct and prolonged effects of EDC exposure in animal models, but many questions remain about molecular mechanisms by which EDCs initially induce epimutations or contribute to the propagation of EDC-induced epimutations either within the exposed generation or to subsequent generations. Additional questions remain regarding the extent to which there may be differences in cell type-specific susceptibilities to various EDCs, and whether this susceptibility is correlative with expression of relevant hormone receptors and/or the location of relevant hormone response elements (HREs) in the genome. To address these questions, we exposed cultured mouse pluripotent (induced pluripotent stem [iPS]), somatic (Sertoli and granulosa), and germ (primordial germ cell like [PGCLCs]) cells to BPS and measured changes in DNA methylation levels at the epigenomic level and gene expression at the transcriptomic level. We found that there was indeed a difference in cell type-specific susceptibility to EDC-induced epimutagenesis and that this susceptibility correlated with differential expression of relevant hormone receptors and, in many cases, tended to generate epimutations near relevant HREs within the genome. Additionally, however, we also found that BPS can induce epimutations in a cell type that does not express relevant receptors and in genomic regions that do not contain relevant HREs, suggesting that both canonical and non-canonical signaling mechanisms can be disrupted by BPS exposure. Most interestingly, we found that when iPS cells were exposed to BPS and then induced to differentiate into PGCLCs, the prevalence of epimutations and differentially expressed genes (DEGs) initially induced in the iPSCs was largely retained in the resulting PGCLCs, however, >90% of the specific epimutations and DEGs were not conserved but were rather replaced by novel epimutations and DEGs following the iPSC to PGCLC transition. These results suggest a unique mechanism by which an EDC-induced epimutated state may be propagated transgenerationally following a single exposure to the causative EDC.
Project description:Endocrine disrupting chemicals (EDCs) such as bisphenol S (BPS) are xenobiotic compounds that can disrupt endocrine signaling following exposure due to steric similarities to endogenous hormones within the body. EDCs have been shown to induce disruptions in normal epigenetic programming (epimutations) that accompany dysregulation of normal gene expression patterns that appear to predispose disease states. Most interestingly, the prevalence of epimutations following exposure to many different EDCs often persists over multiple subsequent generations, even with no further exposure to the causative EDC. Many previous studies have described both the direct and prolonged effects of EDC exposure in animal models, but many questions remain about molecular mechanisms by which EDCs initially induce epimutations or contribute to the propagation of EDC-induced epimutations either within the exposed generation or to subsequent generations. Additional questions remain regarding the extent to which there may be differences in cell type-specific susceptibilities to various EDCs, and whether this susceptibility is correlative with expression of relevant hormone receptors and/or the location of relevant hormone response elements (HREs) in the genome. To address these questions, we exposed cultured mouse pluripotent (induced pluripotent stem [iPS]), somatic (Sertoli and granulosa), and germ (primordial germ cell like [PGCLCs]) cells to BPS and measured changes in DNA methylation levels at the epigenomic level and gene expression at the transcriptomic level. We found that there was indeed a difference in cell type-specific susceptibility to EDC-induced epimutagenesis and that this susceptibility correlated with differential expression of relevant hormone receptors and, in many cases, tended to generate epimutations near relevant HREs within the genome. Additionally, however, we also found that BPS can induce epimutations in a cell type that does not express relevant receptors and in genomic regions that do not contain relevant HREs, suggesting that both canonical and non-canonical signaling mechanisms can be disrupted by BPS exposure. Most interestingly, we found that when iPS cells were exposed to BPS and then induced to differentiate into PGCLCs, the prevalence of epimutations and differentially expressed genes (DEGs) initially induced in the iPSCs was largely retained in the resulting PGCLCs, however, >90% of the specific epimutations and DEGs were not conserved but were rather replaced by novel epimutations and DEGs following the iPSC to PGCLC transition. These results suggest a unique mechanism by which an EDC-induced epimutated state may be propagated transgenerationally following a single exposure to the causative EDC.
Project description:Convergent evidence associates exposure to endocrine disrupting chemicals (EDCs) with major human diseases, even at regulation-compliant concentrations. This might be because humans are exposed to EDC mixtures, whereas chemical regulation is based on a risk assessment of individual compounds. Here, we developed a mixture-centered risk assessment strategy that integrates epidemiological and experimental evidence. We identified that exposure to an EDC mixture in early pregnancy is associated with language delay in offspring. At human-relevant concentrations, this mixture disrupted hormone-regulated and disease-relevant regulatory networks in human brain organoids and in the model organisms Xenopus leavis and Danio rerio, as well as behavioral responses. Reinterrogating epidemiological data, we found that up to 54% of the children had prenatal exposures above experimentally derived levels of concern, reaching, for the upper decile compared with the lowest decile of exposure, a 3.3 times higher risk of language delay.
Project description:Trophoblast stem cells (TSCs) are key for embryo implantation and placentation. Environmental toxicants that compromise trophoblast function could compromise fetal viability, pregnancy outcome, and progeny health. Endocrine disrupting chemicals (EDCs) can epigenetically modify cells and alter their developmental properties. Understanding the effects of low, chronic EDC exposures on TSCs and pregnancy is a priority in developmental toxicology. Differences in placentation between primates and other mammals make a nonhuman primate model ideal for this. We examined effects of chronic low-level exposure to five EDCs on rhesus monkey TSCs in vitro. Two of the toxicants, ATR and TBT, exerted the strongest effects, with substantial overlap. Affected genes included some with obvious relevance to placentation and implantation (WNT7A, INHBA, and cytokines and their receptors). Pathway analysis revealed significant reductions in the expression of genes related to cytokine signaling, a feature shared across all five EDCs tested. Low-level chronic exposure of primate TSCs to EDCs may thus compromise trophoblast development in vivo, modify responses to pathogens and other challenges, and negatively affect embryo implantation and pregnancy rate.
Project description:Endocrine disrupting chemicals (EDCs) are compounds that disrupt normal hormonal signaling. Examples are Xenoestrogens (e.g BPA) and Phytoestrogens (e.g isoflavones). Comparison of EDC treated versus vehicle treated MCF7 parental cells. Each comparison in technical and biological duplicate.
Project description:Endocrine disrupting chemicals (EDCs) exert significant effects on health and physiology, many of which are traceable to effects on stem cell programming underlying organismal development. Understanding risk of low-level, chronic EDC exposure will be enhanced by knowledge of effects on stem cells. We exposed rhesus monkey embryonic stem cells to low levels of five different EDCs for 28 days, and evaluated effects on gene expression by RNAseq transcriptome profiling. EDCs tested included bisphenol A (BPA), atrazine (ATR), tributyltin (TBT), perfluorooctanoic acid (PFOA), and di-(2-ethylhexyl) phthalate (DEHP). We observed little effect of BPA, and small numbers of affected genes (119 or fewer) with the other EDCs. There was substantial overlap in effects across two, three, or four treatments. Ingenuity Pathway analysis indicated suppression of cell survival genes, activation of cell death genes, suppression of genes downstream of several stress response mediators, and modulations in several genes that regulate pluripotency, differentiation, and germ layer development. Potential adverse effects of these changes on development are discussed.
Project description:Endocrine-disrupting chemicals (EDCs) can modulate estrogen receptor (ER) signaling by altering its transcriptional activity. To investigate these effects, we performed chromatin immunoprecipitation sequencing (ChIP-seq) on cells treated with 5α-Dihydrotestosterone (5α-DTT), Flutamide, Estradiol, and Bisphenol B. This dataset includes raw sequencing reads, processed peak files, and metadata, enabling the identification of ER binding sites influenced by each EDC. Gene ontology (GO) analysis of ChIP-enriched regions revealed that these compounds affect key pathways, including antibody-dependent cytotoxicity, BMP signaling in cardiac induction, and hepatocyte growth factor receptor signaling. This dataset provides insights into EDC-induced transcriptional regulation and contributes to the understanding of their role in endocrine disruption.
Project description:Background: Environmental contamination by endocrine disrupting chemicals (EDCs) has created serious public health, ecological, and regulatory concerns. Prenatal exposure can affect a wide range of developing organ systems, adversely affecting behavior, metabolism, fertility, and disease risk in the adult. The most serious and puzzling effect of EDC exposure is the transmission of effects to subsequent unexposed generations (transgenerational effects). This requires the induction of epigenetic changes to the germline that are not subject to the normal processes of erasure and resetting in subsequent generations. Understanding when and how the germline is vulnerable to EDCs is an essential first step in devising strategies to prevent and reverse their effects. Methods: We report here results using a well-established mouse model and the most extensively studied EDC, bisphenol A, to assess effects on the female germline and evaluate the underlying epigenetic changes. Results: Using a quantitative variable (meiotic recombination), we found germline effects across a wide range of doses with a dose-related increase in severity. We identified a period of dramatic changes in chromatin at the onset of meiotic prophase as the vulnerable window of exposure and found a remarkable effect on chromatin that defies meiotic dogma. Oocyte analysis by mass spectrometry and immunofluorescence suggested H4K20me2, a histone posttranslational modification involved in DNA damage repair, was particularly affected. Subsequent RNA-seq analysis revealed a relatively small number of differentially expressed genes, but in addition to genes involved in chromatin dynamics, several with important roles in DNA repair/recombination and centromere stability also were affected. Discussion: Together, our data suggest BPA exposure induces complex changes to the germline that dysregulate chromatin but also affect several critical and interrelated meiotic pathways.
Project description:In this study, we aimed to engineer an in vitro model that better resembles the glandular architecture and hemodynamic perfusion of the native thyroid than current in vitro models, and that can better evaluate the effect of potential endocrine disrupting chemicals (EDCs) on the thyroid. We constructed a human thyroid-on-a-chip (ThyO) model by culturing NKX2-1wt-GFP/PAX8 human embryonic stem cell-derived thyroid organoids in an in-house developed microfluidic system for 7 days. We then performed fluorescence-activated cell sorting (FACS) of NKX2-1+ cells. We compared our ThyO model to static organoid controls using RNA sequencing. In addition, we mechanistically elucidated the effect of 7 days exposure to the EDC benzo(k)fluoranthene (BkF) on thyroid physiology both in the ThyO chip model and static organoids.
Project description:In this study we used RNA-seq to characterize the dose-response for global transcriptomic alterations induced by BPA, BPF, BPS and TBBA in H9 (WA09) human embryonic stem (hES) cells. To assess the relative biological activity and potency of BPA and structural analogs BPS, BPF and TBBP, we examined the stem cell transcriptome in H9 hES cells following exposure to these chemicals at concentrations that covered greater than three orders of magnitude (1 microM to >100 microM). These exposure levels are considered to be near human relevant and range from noncytotoxic to overtly toxic. Overall, this study provides basic mechanistic information about the effects of BPA and structural analogs BPS, BPF and TBBP on the transcriptome of hES cells and demonstrates how these data can be applied to derive benchmark dose modeling (BMD) information useful for comparing relative potencies of these structurally related chemicals.