DEVELOPMENTAL TOXICITY OF ORGANOPHOSPHATE-BASED FLAME RETARDANTS

有机磷酸酯阻燃剂的发育毒性

• 批准号: 9186743
• 负责人: David C. Volz
• 金额: $ 14.88万
• 依托单位: UNIVERSITY OF CALIFORNIA RIVERSIDE
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-05-09 至 2017-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9186743
• 关键词: DEVELOPMENTAL; TOXICITY; ORGANOPHOSPHATE; BASED; FLAME

DESCRIPTION (provided by applicant): In 2005, the commercial polybrominated diphenyl ether (PBDE) mixture known as PentaBDE - a widely used brominated flame retardant (FR) - was voluntarily phased out in the United States due to concerns about persistence, bioaccumulation, and toxicity. Due to increased use as PentaBDE replacements, organophosphate-based FRs (OPFRs) have now been detected at concentrations comparable to and, in some cases, higher than total PBDE concentrations in household dust, suggesting that chronic human exposure is common within the US. Using zebrafish as a model, our long-term goal is to identify xenobiotic-mediated pathways that contribute to adverse outcomes during early vertebrate development. As a step toward this long-term goal, the objective of this application is to uncover mechanisms of developmental toxicity for two high-production volume OPFRs commonly detected within indoor environments. Our central hypothesis is that two major classes of OPFRs - chlorinated phosphate esters (CPEs) and aryl phosphate esters (APEs) - widely used as FRs and plasticizers exhibit distinct modes of action during embryogenesis. Specifically, our working hypotheses are that (1) the CPE tris(1,3-dichloro-2-propyl) phosphate (TDCPP) inhibits DNA methyltransferase (DNMT) activity and, as a result, delays zygotic genome methylation during early embryogenesis and (2) the APE triphenyl phosphate (TPP) prevents normal cardiac looping through aberrant activation of a retinoic acid receptor (RAR)-dependent pathway. These hypotheses were formulated based on preliminary data from the applicant's laboratory. The central hypothesis will be tested by pursuing two specific aims: 1) Identify the epigenetic mechanism responsible for TDCPP-induced delays in zygotic genome methylation during cleavage; and 2) Identify the role of aberrant RAR activation in TPP-induced looping impairments during heart morphogenesis. For the first aim, we will rely on a combination of early embryonic exposures, fluorometric DMNT activity assays, and methylated DNA affinity capture coupled with high- throughput next-generation sequencing (MethylCap-seq). For the second aim, we will rely on a combination of high-content screening (HCS) assays, reverse genetics, real-time PCR, and in vitro human RAR reporter assays. The proposed research is innovative because, for the first time, we will leverage the power of (1) MethylCap-seq to reveal chemically-induced effects on the zebrafish embryonic methylome and (2) our existing 384-well-based HCS assays coupled with reverse genetics to identify the role of RAR activation in chemically-induced effects on cardiovascular development within zebrafish embryos. This contribution is significant because it (1) begins to address key uncertainties about mechanisms of developmental OPFR toxicity; (2) helps prioritize targeted, mechanism-focused evaluations using human cell line-based assays and prenatal developmental toxicity studies within rodents; and (3) raises questions about the potential health risks of two widely used OPFRs to developing human embryos resulting from chronic and ubiquitous exposure.

描述（由申请人提供）：2005年，由于对持久性、生物累积性和毒性的担忧，美国自愿淘汰了被称为五溴二苯醚的商用多溴二苯醚混合物-一种广泛使用的溴化阻燃剂。由于五溴二苯醚替代品的使用越来越多，现已检测到有机磷阻燃剂的浓度与家庭灰尘中的多溴二苯醚总浓度相当，在某些情况下甚至高于多溴二苯醚总浓度，这表明人类长期接触五溴二苯醚在美国很常见。以斑马鱼为模型，我们的长期目标是确定在早期脊椎动物发育过程中导致不良后果的外源性介导的途径。作为实现这一长期目标的一步，本申请的目的是揭示在室内环境中通常检测到的两种高产量OPFR的发育毒性机制。我们的中心假设是，两个主要类别的OPFR-氯化磷酸酯（CPE）和芳基磷酸酯（APE）-广泛用作FR和增塑剂表现出不同的作用模式在胚胎发育过程中。具体而言，我们的工作假设是：（1）CPE三（1，3-二氯-2-丙基）磷酸盐（TDCPP）抑制DNA甲基转移酶（DNMT）活性，因此，延迟早期胚胎发生期间合子基因组甲基化;（2）APE磷酸三苯酯（TPP）通过异常激活视黄酸受体（RAR）依赖性途径阻止正常心脏循环。这些假设是根据申请人实验室的初步数据制定的。将通过追求两个特定目标来检验中心假设：1）确定负责TDCPP诱导的合子基因组甲基化延迟的表观遗传机制; 2）确定心脏形态发生期间异常RAR激活在TPP诱导的成环损伤中的作用。对于第一个目标，我们将依赖于早期胚胎暴露、荧光DMNT活性测定和甲基化DNA亲和捕获以及高通量下一代测序（MethylCap-seq）的组合。对于第二个目标，我们将依靠高含量筛选（HCS）测定，反向遗传学，实时PCR和体外人类RAR报告基因测定的组合。拟议的研究是创新的，因为我们将首次利用（1）MethylCap-seq的力量来揭示化学诱导对斑马鱼胚胎甲基化的影响，以及（2）我们现有的基于384孔的HCS测定与反向遗传学相结合，以确定RAR激活在化学诱导对斑马鱼胚胎心血管发育影响中的作用。这一贡献是重要的，因为它（1）开始解决关于发育OPFR毒性机制的关键不确定性;（2）有助于优先考虑使用基于人类细胞系的测定和啮齿动物产前发育毒性研究进行有针对性的、以机制为重点的评价;（3）提出了关于两种广泛使用的OPFR因长期和普遍暴露而对发育中的人类胚胎造成的潜在健康风险的问题。

项目成果

Triphenyl phosphate-induced developmental toxicity in zebrafish: potential role of the retinoic acid receptor.

• DOI: 10.1016/j.aquatox.2015.02.009
• 发表时间: 2015-04
• 期刊: Aquatic toxicology (Amsterdam, Netherlands)
• 作者: Isales GM;Hipszer RA;Raftery TD;Chen A;Stapleton HM;Volz DC
• 通讯作者: Volz DC

Tris(1,3-dichloro-2-propyl)phosphate Induces Genome-Wide Hypomethylation within Early Zebrafish Embryos.

• DOI: 10.1021/acs.est.6b03656
• 发表时间: 2016-09-20
• 期刊: ENVIRONMENTAL SCIENCE & TECHNOLOGY
• 影响因子: 11.4
• 作者: Volz, David C.;Leet, Jessica K.;Chen, Albert;Stapleton, Heather M.;Katiyar, Neerja;Kaundal, Rakesh;Yu, Yang;Wang, Yinsheng
• 通讯作者: Wang, Yinsheng