Project description:Polychlorinated diphenyl ethers are lipophilic, persistent, and bioaccumulable compounds widely used as flame-retardants. These are chemicals of increasing environmental concern due to their lipophilic, persistent, and bioaccumulable characteristics. The objective of this study was to analyze the potential bioavailability and bioaccumulation of BDE-209 as a source of toxicity. Zebrafish embryos were exposed for 8 days to sediments spiked with an environmentally relevant concentration of BDE-209. We analyzed gene expression changes, thyroid function, and several markers for neurotoxicity. Results of this research highlight the need to consider the capability of BDE-209 to be bioavailable and bioaccumulate, indicating the potential hazardous effects.
Project description:Polychlorinated diphenyl ethers are lipophilic, persistent, and bioaccumulable compounds widely used as flame-retardants. These are chemicals of increasing environmental concern due to their lipophilic, persistent, and bioaccumulable characteristics. The objective of this study was to analyze the potential bioavailability and bioaccumulation of BDE-209 as a source of toxicity. Zebrafish embryos were exposed for 8 days to sediments spiked with an environmentally relevant concentration of BDE-209. We analyzed gene expression changes, thyroid function, and several markers for neurotoxicity. Results of this research highlight the need to consider the capability of BDE-209 to be bioavailable and bioaccumulate, indicating the potential hazardous effects. Total RNA was isolated using RNeasy kits (Qiagen, Valencia, CA, USA). The RNA quality was assessed with an Agilent 2100 Bioanalyzer (Agilent, Wilmington, DE, USA) and quantity was determined using a NanodropM-BM-. ND-1000 spectrophotometer. Total RNA was stored at -80oC until analyzed with oligonucleotide microarrays. Zebrafish 44,000 gene arrays (Agilent Single Color 19161, Platform number GPL6457) were purchased from Agilent (Sta. Clara, CA, USA). The Agilent one-color microarray hybridization protocol (One-Color Microarray-Based Gene Expression Analysis, version 5.7, Agilent Technologies, Palo Alto, CA) was used for microarray hybridizations following the manufacturerM-bM-^@M-^Ys protocol and recommendations. Four controls and four treated samples were analyzed, each sample consisting of a pool of embryos. One ug of total RNA was used for all hybridizations. cDNA synthesis, cRNA labeling, amplification and hybridization were performed following the manufacturerM-bM-^@M-^Ys kits and protocols (Quick Amp Labeling kit; Agilent, Palo Alto, CA). An Axon GenePixM-BM-. 4000B Microarray Scanner (Molecular Devices Inc., Sunnyvale, CA) was used to scan microarray images at 5 M-NM-<m resolution. Data were resolved from microarray images using Agilent Feature Extraction software and analyzed using GeneSpring (Agilent Technologies, Palo Alto, CA).
Project description:Flame retardants are detected globally in the environment, and pose great risks to human health. The potential effects of these chemicals on the development of nervous system have raise public concerns. In this study, to explore the toxicity profiles of these chemicals in the early developmental stage of human nervous system, we induced neural ectoderm from human embryonic stem cells in the presence of individual or mixture of BDE-47, BDE-209, TBBPA, TBBPS, TCBPA. By analyzing the whole transcriptional changes in the samples treated with 1 μΜ of each chemical, we identified a set of neural development relative biological processes that response to these chemicals. Genes involved in the GO terms relative to neural development were further confirmed by qRT-PCR assay, with samples treated with various concentrations (10 nM, 100 nM, 1 μΜ, 5 μΜ) of these chemicals. We found out that axon guidance and synaptogenesis may be the major target of these chemicals. In addition, these flame retardants may dysregulate the WNT and AHR signaling pathways. BDE-209 showed similar toxicity with BDE-47, whereas TBBPS and TCBPA may not be safe alternatives to TBBPA.
Project description:Polybrominated diphenyl ethers (PBDEs) are persistent organic chemicals implied as flame re-tardants. Humans are mainly exposed to BDE-47, -99 and -209 congeners by diet. PBDEs are metabolic disruptors with liver as main target organ. To investigate their mode of action at a human relevant concentration, we exposed HepG2 cells to these congeners and their mixture at 1 nM for 72h, analyzing their transcriptomic and proteomic profiles. KEGG pathways and GSEA Hallmarks enrichment analyses evidenced that BDE-47 disrupted the glucose metabolism and Hypoxia pathway; all the congeners and the MIX affected lipid metabolism and signaling Hallmarks regulating metabolism as mTORC1 and PI3K/AKT/MTOR. These results were confirmed by glucose secretion depletion and increased lipid accumulation, especially in BDE-47 and -209 treated cells. These congeners also affected the EGFR/MAPK signaling; further, BDE-47 enriched the Estrogen pathway. Interestingly, BDE-209 and the MIX increased ERα gene expression, whereas all the congeners and the MIX induced ERβ and PPARγ. We also found that PBDEs modulated several lncRNAs and that HNRNAP1 represented a central hub in all the four interaction networks. Overall, despite the low concentration used, the PBDEs investigated affected glucose and lipid metabolism with different underlying modes of action, as highlighted by the integrated omics analysis. These results may support the mechanism-based risk assessment of these compounds in relation to liver metabolism disruption.
Project description:Polybrominated diphenyl ethers (PBDEs) were used as flame-retardant additives in a wide range of polymers starting in 1965 and were recently withdrawn from commerce in North America and Europe. Generations that were exposed perinatally to the highest environmental doses of PBDE have now reached 5-20 years of age and in the U.S. account for 1/5 of the total population. Emerging data indicates long-term impairment of metabolic health by PBDE exposure in humans and laboratory animals. We hypothesize that exposure to PBDE during sensitive developmental windows may result in long-lasting changes in liver metabolism. In this study pregnant CD-1 mice were exposed to 0.2 mg/kg 2,2’,4,4’-tetrabromodiphenyl ether (BDE-47) from gestation day 8 till postnatal day 21 and liver RNA-seq was performed on the last day of dam exposure and on postnatal week 20 in male offspring. Several groups of metabolic genes, including ribosomal and mitochondrial genes were significantly upregulated at both time-points. Genes regulated via mechanistic target of rapamycin (mTOR pathway), the gatekeeper of metabolic homeostasis, were whether up- or down- regulated at both time-points. Thus, perinatal exposure to environmentally relevant doses of BDE-47 in laboratory mice results in long-lasting changes in liver metabolism. Our evidence suggests involvement of the mTOR pathway in the observed metabolic programming of liver.
Project description:Polybrominated diphenyl ethers (PBDEs) were used as flame-retardant additives starting 1965 and were recently withdrawn from commerce in North America and Europe. Approximately 1/5 of the total U.S. population were born when environmental concentrations of PBDE plateaued at their maximum. Accumulating evidence suggests that developmental exposures to PBDE may result in long-lasting programming of liver metabolism. In this study, CD-1 mice were exposed prenatally or neonatally to 1 mg/kg body weight of 2,2’,4,4’-tetrabromodiphenyl ether (BDE-47), and changes in liver gene histology, transcriptome, and liver-blood balance of triglycerides were analyzed in 10 month old male offspring. In both exposure groups, long-term reprogramming of lipid metabolism was observed, including increased liver triglycerides and decreased blood triglycerides, and altered expression of metabolic genes in the liver. Significant upregulation of lipid influx transporter Cd36 2.3- and 5.7-fold in pre- and neonatal exposure groups respectively was identified as a potential mechanism of blood/liver imbalance of triglycerides. Analysis of our and previously published all-genome gene expression data identified changes in expression of ribosomal protein genes as a transcriptomic signature of PBDE exposure. Further comparison of our new data and published data demonstrate that low doses (0.2 mg/kg body weight) of PBDE induce long-lasting up-regulation of ribosomal genes, suppression of Cd36 in liver and increase circulating triglycerides in blood, while moderated doses (≥ 1 mg/kg body weight) produce opposite long-lasting effects. To conclude, this study shows that an environmentally relevant developmental exposures to BDE-47 permanently alter lipid uptake and accumulation in the liver, with low and moderate doses having opposite effect on liver transcriptomics and triglyceride balance. Similar effects of pre- and neonatal exposures point at hepatocyte maturation as a sensitive window of the liver metabolism programming. These results suggest that PBDE exposure may be an important factor increasing risks of cardio-vascular disease and non-alcoholic fatty liver disease. The translational relevance of these findings for human remain to be studied.
Project description:Background: Polybrominated diphenyl ethers are a group of flame-retardant chemicals appearing increasingly in the environment. Their health effects and mechanisms of toxicity are poorly understood.Objectives: We screened for the sensitive effects and mechanisms of toxicity of 2,2 ,4,4 -tetra-bromodiphenyl ether (BDE-47) by analyzing the gene expression profile in rats exposed to doses comparable to human exposure.Methods: Wistar dams were exposed to vehicle or BDE-47 (0.002 and 0.2 mg/kg body weight) every fifth day from gestation day 15 to postnatal day 20 by injections to caudal vein. Total RNA was extracted from the livers of pups and hybridized to the whole-genome RNA expression micro-arrays. The list of genes 2-fold differentially expressed was exported to PANTHER and Ingenuity Systems for analysis of enriched ontology groups and molecular pathways.Results: Oxidoreductase and transferase protein families were enriched in exposed rats as were these biological process categories: carbohydrate metabolism; electron transport; and lipid, fatty acid, and steroid metabolism. Four signaling pathways (cascades of activation of drug-metabolizing enzymes) and 10 metabolic pathways were significantly enriched. Drug-metabolizing enzymes appear to be regulated by BDE-47 through an aryl hydrocarbon receptorindependent mechanism. Direct interaction with retinoid X receptor or its upstream cascade may be involved. The main metabolic effects consisted of activation of metabolic pathways: alpha- and omega-oxidation of fatty acids, glycolysis, and starch hydrolysis.Conclusions: Altered expression of genes involved in metabolic and signaling pathways and functions of the organism occurs after perinatal exposure of rat offspring to BDE-47 at doses relevant for the general population.
Project description:Methylmercury (MeHg) is an environmental neurotoxicant known to cause adverse effects in fish, such as locomotor abnormalities, visual deficits or teratogenesis. However, very few studies have investigated the effects of environmentally realistic MeHg exposures on the gene expression of fish embryos. Since the primary source of MeHg exposure in wild fish is through the diet, this study analyzed differential gene expression in zebrafish embryos from parents that had been subjected to environmentally relevant dietary MeHg exposures (0, 1, 3, and 10ppm) throughout their whole life cycle.