Developmental Toxicity Assessment of Piperonyl Butoxide Exposure Targeting Sonic Hedgehog Signaling and Forebrain and Face Morphogenesis in the Mouse: An in Vitro and in Vivo Study
Developmental Toxicity Assessment of Piperonyl Butoxide Exposure Targeting Sonic Hedgehog Signaling and Forebrain and Face Morphogenesis in the Mouse: An in Vitro and in Vivo Study
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DOI：
10.1289/ehp5260
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发表时间：
2019-10-01
影响因子：
10.4
通讯作者：
Lipinski, Robert J.
中科院分区：
文献类型：
--
作者：
Everson, Joshua L.;Sun, Miranda R.;Lipinski, Robert J.
背景：丁醚双壬酯（PBO）是一种在住宅、商业和农业环境中使用的杀虫剂。PBO最近被发现抑制Sonic hedgehog（Shh）信号传导，这是一种关键的发育调控途径。Shh信号传导的中断与出生缺陷有关，包括前脑无裂畸形（HPE），前脑和面部的畸形被认为是由复杂的基因-环境相互作用引起的。结果：PBO对Shh信号传导的影响在体外和前脑和面部发育在体内进行了检查。为了检查其致畸潜力，在妊娠第7.75天通过口服和灌胃向C57 BL/6J小鼠施用单剂量的PBO（22 - 1，800 mg/kg），靶向HPE的关键期。用Shh（+）（/-）小鼠模型研究了基因-环境相互作用，该模型模拟了人类HPE相关的基因突变.结果：PBO通过与已知致畸剂环巴胺类似的机制在体外减弱Shh信号传导。子宫内PBO暴露导致特征性HPE面部畸形，包括剂量依赖性面中部发育不全和距离缩短，最低可观察效应水平为67 mg/kg。在严重受累动物中观察到HPE的中位前脑缺陷特征，而所有有效剂量均破坏了产生皮质中间神经元的Shh依赖性瞬时前脑结构的发育。通常沉默的杂合子Shh无效突变加剧PBO致畸性在所有测试剂量，包括33毫克/公斤。讨论：这些研究结果表明，产前PBO暴露可能会导致明显的前脑和面部畸形或神经发育中断与微妙或没有颅面畸形小鼠。通过靶向Shh信号传导作为敏感的作用机制并检查基因-环境相互作用，该研究定义了小鼠中PBO发育毒性的最低可观察效应水平，比先前认识到的低30倍以上。人类暴露于PBO及其潜在的贡献，病因复杂的出生缺陷，应严格审查。
BACKGROUND: Piperonyl butoxide (PBO) is a pesticide synergist used in residential, commercial, and agricultural settings. PBO was recently found to inhibit Sonic hedgehog (Shh) signaling, a key developmental regulatory pathway. Disruption of Shh signaling is linked to birth defects, including holoprosencephaly (HPE), a malformation of the forebrain and face thought to result from complex gene-environment interactions.OBJECTIVES: The impact of PBO on Shh signaling in vitro and forebrain and face development in vivo was examined.METHODS: The influence of PBO on Shh pathway transduction was assayed in mouse and human cell lines. To examine its teratogenic potential, a single dose of PBO (22-1,800 mg/kg) was administered by oral &avage to C57BL/6J mice at gestational day 7.75, targeting the critical period for HPE. Gene-environment interactions were investigated using Shh(+)(/-) mice, which model human HPE-associated genetic mutations.RESULTS: PBO attenuated Shh signaling in vitro through a mechanism similar to that of the known teratogen cyclopamine. In utero PBO exposure caused characteristic HPE facial dysmorphology including dose-dependent midface hypoplasia and hypotelorism, with a lowest observable effect level of 67 mg/kg. Median forebrain deficiency characteristic of HPE was observed in severely affected animals, whereas all effective doses disrupted development of Shh-dependent transient forebrain structures that generate cortical interneurons. Normally silent heterozygous Shh null mutations exacerbated PBO teratogenicity at all doses tested, including 33 mg/kg.DISCUSSION: These findings demonstrate that prenatal PBO exposure can cause overt forebrain and face malformations or neurodevelopmental disruptions with subtle or no craniofacial dysmorphology in mice. By targeting Shh signaling as a sensitive mechanism of action and examining gene-environment interactions, this study defined a lowest observable effect level for PBO developmental toxicity in mice more than 30-fold lower than previously recognized. Human exposure to PBO and its potential contribution to etiologically complex birth defects should be rigorously examined.