Dataset Information

The widely utilized brominated flame retardant tetrabromobisphenol A (TBBPA) is a potent inhibitor of the SERCA Ca2+ pump.

ABSTRACT: TBBPA (tetrabromobisphenol A) is currently the most widely used type of BFR (brominated flame retardant) employed to reduce the combustibility of a large variety of electronic and other manufactured products. Recent studies have indicated that BFRs, including TBBPA, are bio-accumulating within animal and humans. BFRs including TBBPA have also been shown to be cytotoxic and potentially endocrine-disrupting to a variety of cells in culture. Furthermore, TBBPA has specifically been shown to cause disruption of Ca2+ homoeostasis within cells, which may be the underlying cause of its cytotoxicity. In this study, we have demonstrated that TBBPA is a potent non-isoform-specific inhibitor of the SERCA (sarcoplasmic/endoplasmic reticulum Ca2+-ATPase) (apparent K(i) 0.46-2.3 microM), thus we propose that TBBPA inhibition of SERCA contributes in some degree to Ca2+ signalling disruption. TBBPA binds directly to the SERCA without the need to partition into the phospholipid bilayer. From activity results and Ca2+-induced conformational results, it appears that the major effect of TBBPA is to decrease the SERCA affinity for Ca2+ (increasing the K(d) from approx. 1 microM to 30 microM in the presence of 10 microM TBBPA). Low concentrations of TBBPA can quench the tryptophan fluorescence of the SERCA and this quenching can be reversed by BHQ [2,5-di-(t-butyl)-1,4-hydroquinone] and 4-n-nonylphenol, but not thapsigargin, indicating that TBBPA and BHQ may be binding to similar regions in the SERCA.

SUBMITTER: Ogunbayo OA

PROVIDER: S-EPMC2267361 | biostudies-literature | 2007 Dec

REPOSITORIES: biostudies-literature

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The widely utilized brominated flame retardant tetrabromobisphenol A (TBBPA) is a potent inhibitor of the SERCA Ca2+ pump.

Ogunbayo Oluseye A OA Michelangeli Francesco F

The Biochemical journal 20071201 3

TBBPA (tetrabromobisphenol A) is currently the most widely used type of BFR (brominated flame retardant) employed to reduce the combustibility of a large variety of electronic and other manufactured products. Recent studies have indicated that BFRs, including TBBPA, are bio-accumulating within animal and humans. BFRs including TBBPA have also been shown to be cytotoxic and potentially endocrine-disrupting to a variety of cells in culture. Furthermore, TBBPA has specifically been shown to cause d ...[more]

PMID: 17784851

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Project description:3,3’,5.5’-Tetrabromobisphenol A (TBBPA) is a widely used brominated flame-retardant utilized in the production of electronic devices and plastic paints. The objective of this study is to use zebrafish as a model and determine the effects of TBBPA exposure on early embryogenesis. We initiated TBBPA exposures (0, 10, 20 and 40μM) at 0.75 h post fertilization (hpf) and monitored early developmental events such as cleavage, blastula and epiboly that encompass maternal-to-zygotic transition (MZT) and zygotic genome activation (ZGA). Our data revealed that TBBPA exposures induced onset of developmental delays by 3 hpf (blastula). By 5.5 hpf (epiboly), TBBPA-exposed (10-20 μM) embryos showed concentration-dependent developmental lag by up to 3 stages or 100% mortality at 40 μM. Interestingly, while continued 0.75- 48 hpf TBBPA exposures (10 μM) led to severely deformed embryos, replacing exposure solution with chemical-free media at 6 hpf mitigated this effect, with 100% normal embryos at 48 hpf. To examine the genetic basis of TBBPA-induced delays, we conducted mRNA-sequencing on embryos exposed to 0 or 40 μM TBBPA from 0.75 hpf to 2, 3.5 or 4.5 hpf. Read count data showed that while TBBPA exposures had no overall impacts on maternal or maternal-zygotic genes, collective read counts for zygotically activated genes were lower in TBBPA treatment at 4.5 hpf compared to time-matched controls, suggesting that TBBPA delays ZGA. Gene ontology assessments for both time- and stage-matched differentially expressed genes revealed TBBPA-induced inhibition of chromatin assembly- a process regulated by histone modifications. Since acetylation is the primary histone modification system operant during early ZGA, we hypothesized that TBBPA inhibits histone acetylation, resulting in lack of open chromatin within promoters of zygotic genes and delaying ZGA. Therefore, we co-exposed embryos to 20 μM TBBPA and 100 μM N-(4-Chloro-3-(trifluoromethyl)phenyl)-2-ethoxybenzamide (CTB) -a histone acetyltransferase activator that promotes histone acetylation- and showed that TBBPA-CTB co-exposures from 0.75- 3 hpf significantly reversed TBBPA-only developmental delays, suggesting that TBBPA-induced phenotypes are indeed driven by repression of histone acetylation. Collectively, our work demonstrates that TBBPA disrupts ZGA and early developmental morphology, potentially by inhibiting histone acetylation. Future studies will focus on mechanisms of TBBPA-induced chromatin modifications.

Dataset Information

The widely utilized brominated flame retardant tetrabromobisphenol A (TBBPA) is a potent inhibitor of the SERCA Ca2+ pump.

Publications

The widely utilized brominated flame retardant tetrabromobisphenol A (TBBPA) is a potent inhibitor of the SERCA Ca2+ pump.

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