Dataset Information

Mono-substituted isopropylated triaryl phosphate, a major component of Firemaster 550, is an AHR agonist that exhibits AHR-independent cardiotoxicity in zebrafish.

ABSTRACT: Firemaster 550 (FM550) is an additive flame retardant mixture used within polyurethane foam and is increasingly found in house dust and the environment due to leaching. Despite the widespread use of FM550, very few studies have investigated the potential toxicity of its ingredients during early vertebrate development. In the current study, we sought to specifically investigate mono-substituted isopropylated triaryl phosphate (mITP), a component comprising approximately 32% of FM550, which has been shown to cause cardiotoxicity during zebrafish embryogenesis. Previous research showed that developmental defects are rescued using an aryl hydrocarbon receptor (AHR) antagonist (CH223191), suggesting that mITP-induced toxicity was AHR-dependent. As zebrafish have three known AHR isoforms, we used a functional AHR2 knockout line along with AHR1A- and AHR1B-specific morpholinos to determine which AHR isoform, if any, mediates mITP-induced cardiotoxicity. As in silico structural homology modeling predicted that mITP may bind favorably to both AHR2 and AHR1B isoforms, we evaluated AHR involvement in vivo by measuring CYP1A mRNA and protein expression following exposure to mITP in the presence or absence of CH223191 or AHR-specific morpholinos. Based on these studies, we found that mITP interacts with both AHR2 and AHR1B isoforms to induce CYP1A expression. However, while CH223191 blocked mITP-induced CYP1A induction and cardiotoxicity, knockdown of all three AHR isoforms failed to block mITP-induced cardiotoxicity in the absence of detectable CYP1A induction. Overall, these results suggest that, while mITP is an AHR agonist, mITP causes AHR-independent cardiotoxicity through a pathway that is also antagonized by CH223191.

SUBMITTER: Gerlach CV

PROVIDER: S-EPMC4090055 | biostudies-literature | 2014 Sep

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Mono-substituted isopropylated triaryl phosphate, a major component of Firemaster 550, is an AHR agonist that exhibits AHR-independent cardiotoxicity in zebrafish.

Gerlach Cory V CV Das Siba R SR Volz David C DC Bisson William H WH Kolluri Siva K SK Tanguay Robert L RL

Aquatic toxicology (Amsterdam, Netherlands) 20140516

Firemaster 550 (FM550) is an additive flame retardant mixture used within polyurethane foam and is increasingly found in house dust and the environment due to leaching. Despite the widespread use of FM550, very few studies have investigated the potential toxicity of its ingredients during early vertebrate development. In the current study, we sought to specifically investigate mono-substituted isopropylated triaryl phosphate (mITP), a component comprising approximately 32% of FM550, which has be ...[more]

PMID: 24865613

Similar Datasets

Project description:Firemaster® 550 (FM550) is a chemical mixture currently used as an additive flame retardant in commercial products, and is comprised of 2-ethylhexyl-2,3,4,5-tertrabromobenzoate (TBB), bis(2-ethylhexyl) tetrabromophthalate (TBPH), triphenyl phosphate (TPP), and isopropylated triphenyl phosphate (IPTP). Animal and in vitro studies suggest that FM550, TPP and IPTP may have adipogenic effects and may exert these effects through PPARγ activation. Using murine 3T3-L1 preadipocytes, we investigated the detailed expression of transcription factors and adipogenic markers in response to FM550 and its components. Further we investigated the mechanism of action of the peroxisome proliferator-activated receptor gamma (PPARγ) on downstream targets of the receptor by focussing on the mature adipocyte marker, adipocyte protein 2 (aP2). In addition, we set to elucidate the components responsible for the adipogenic effects seen in the FM550 mixture. We show that FM550 and its components TPP, IPTP, and TBPH, but not TBB induced lipid accumulation in a dose-dependent manner. Interestingly, despite displaying enhanced lipid accumulation, TBPH did not alter the mRNA or protein expression of terminal differentiation markers. In contrast, FM550, TPP, and IPTP treatment enhanced lipid accumulation, and mRNA and protein expression of terminal differentiation markers. To further delineate the mechanisms of action of FM550 and its components we focussed on aP2 promoter activity. For this purpose we used the enhancer region of the mouse aP2 promoter using a 584-bp reporter construct containing an active PPRE located 5.4 kb away from the transcription start site of aP2. Exposure to FM550, IPTP, and TPP significantly increased PPARγ mediated aP2 enhancer activity. Furthermore, we show that TPP- and IPTP-dependent upregulation of aP2 was significantly inhibited by the selective PPARγ antagonist GW9662. In addition, chromatin immunoprecipitation experiments showed that IPTP and TPP treatment led to the recruitment of PPARγ to the regulatory region of aP2.

Project description:BackgroundExposure to flame retardants has been associated with negative health outcomes including metabolic effects. As polybrominated diphenyl ether flame retardants were pulled from commerce, human exposure to new flame retardants such as Firemaster® 550 (FM550) has increased. Although previous studies in murine systems have shown that FM550 and its main components increase adipogenesis, the effects of FM550 in human models have not been elucidated.ObjectivesThe objectives of this study were to determine if FM550 and its components are active in human preadipocytes, and to further investigate their mode of action.MethodsHuman primary preadipocytes were differentiated in the presence of FM550 and its components. Differentiation was assessed by lipid accumulation and expression of peroxisome proliferator-activated receptor γ (PPARG), fatty acid binding protein (FABP) 4 and lipoprotein lipase (LPL). mRNA was collected for Poly (A) RNA sequencing and was used to identify differentially expressed genes (DEGs). Functional analysis of DEGs was undertaken in Ingenuity Pathway Analysis.ResultsFM550 triphenyl phosphate (TPP) and isopropylated triphenyl phosphates (IPTP), increased adipogenesis in human primary preadipocytes as assessed by lipid accumulation and mRNA expression of regulators of adipogenesis such as PPARγ, CCAAT enhancer binding protein (C/EBP) α and sterol regulatory element binding protein (SREBP) 1 as well as the adipogenic markers FABP4 LPL and perilipin. Poly (A) RNA sequencing analysis revealed potential modes of action including liver X receptor/retinoid X receptor (LXR/RXR) activation, thyroid receptor (TR)/RXR, protein kinase A, and nuclear receptor subfamily 1 group H members activation.ConclusionsWe found that FM550, and two of its components, induced adipogenesis in human primary preadipocytes. Further, using global gene expression analysis we showed that both TPP and IPTP likely exert their effects through PPARG to induce adipogenesis. In addition, IPTP perturbed signaling pathways that were not affected by TPP. https://doi.org/10.1289/EHP1318.

Project description:IntroductionFlame retardants (FRs) are common bodily and environmental pollutants, creating concern about their potential toxicity. We and others have found that the commercial mixture FireMaster® 550 (FM 550) or its individual brominated (BFR) and organophosphate ester (OPFR) components are potential developmental neurotoxicants. Using Wistar rats, we previously reported that developmental exposure to FM 550 or its component classes produced sex- and compound-specific effects on adult socioemotional behaviors. The underlying mechanisms driving the behavioral phenotypes are unknown.MethodsTo further mechanistic understanding, here we conducted transcriptomics in parallel with a novel lipidomics approach using cortical tissues from newborn siblings of the rats in the published behavioral study. Inclusion of lipid composition is significant because it is rarely examined in developmental neurotoxicity studies. Pups were gestationally exposed via oral dosing to the dam to FM 550 or the BFR or OPFR components at environmentally relevant doses.ResultsThe neonatal cortex was highly sexually dimorphic in lipid and transcriptome composition, and males were more significantly impacted by FR exposure. Multiple adverse modes of action for the BFRs and OPFRs on neurodevelopment were identified, with the OPFRs being more disruptive than the BFRs via multiple mechanisms including dysregulation of mitochondrial function and disruption of cholinergic and glutamatergic systems. Disrupted mitochondrial function by environmental factors has been linked to a higher risk of autism spectrum disorders and neurodegenerative disorders. Impacted lipid classes included ceramides, sphingomyelins, and triacylglycerides. Robust ceramide upregulation in the OPFR females could suggest a heightened risk of brain metabolic disease.ConclusionsThis study reveals multiple mechanisms by which the components of a common FR mixture are developmentally neurotoxic and that the OPFRs may be the compounds of greatest concern.

Dataset Information

Mono-substituted isopropylated triaryl phosphate, a major component of Firemaster 550, is an AHR agonist that exhibits AHR-independent cardiotoxicity in zebrafish.

Publications

Mono-substituted isopropylated triaryl phosphate, a major component of Firemaster 550, is an AHR agonist that exhibits AHR-independent cardiotoxicity in zebrafish.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets