Department of Environmental and Molecular Toxicology, The Environmental Health Sciences Center, Oregon State University, Corvallis, OR, USA.
Toxicol Appl Pharmacol. 2013 Nov 1;272(3):656-70. doi: 10.1016/j.taap.2013.04.024. Epub 2013 May 5.
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the environment as components of fossil fuels and by-products of combustion. These multi-ring chemicals differentially activate the aryl hydrocarbon receptor (AHR) in a structurally dependent manner, and induce toxicity via both AHR-dependent and -independent mechanisms. PAH exposure is known to induce developmental malformations in zebrafish embryos, and recent studies have shown cardiac toxicity induced by compounds with low AHR affinity. Unraveling the potentially diverse molecular mechanisms of PAH toxicity is essential for understanding the hazard posed by complex PAH mixtures present in the environment. We analyzed transcriptional responses to PAH exposure in zebrafish embryos exposed to benz(a)anthracene (BAA), dibenzothiophene (DBT) and pyrene (PYR) at concentrations that induced developmental malformations by 120 h post-fertilization (hpf). Whole genome microarray analysis of mRNA expression at 24 and 48 hpf identified genes that were differentially regulated over time and in response to the three PAH structures. PAH body burdens were analyzed at both time points using GC-MS, and demonstrated differences in PAH uptake into the embryos. This was important for discerning dose-related differences from those that represented unique molecular mechanisms. While BAA misregulated the least number of transcripts, it caused strong induction of cyp1a and other genes known to be downstream of the AHR, which were not induced by the other two PAHs. Analysis of functional roles of misregulated genes and their predicted regulatory transcription factors also distinguished the BAA response from regulatory networks disrupted by DBT and PYR exposure. These results indicate that systems approaches can be used to classify the toxicity of PAHs based on the networks perturbed following exposure, and may provide a path for unraveling the toxicity of complex PAH mixtures.
多环芳烃(PAHs)作为化石燃料的组成部分和燃烧的副产品,广泛存在于环境中。这些多环化学物质以结构依赖的方式差异激活芳基烃受体(AHR),并通过 AHR 依赖和非依赖机制诱导毒性。PAH 暴露已知会导致斑马鱼胚胎发育畸形,最近的研究表明,低 AHR 亲和力化合物会引起心脏毒性。揭示 PAH 毒性的潜在多样化分子机制对于理解环境中存在的复杂 PAH 混合物所构成的危害至关重要。我们分析了暴露于苯并(a)蒽(BAA)、二苯并噻吩(DBT)和芘(PYR)的斑马鱼胚胎在受精后 120 小时(hpf)时的 PAH 暴露的转录反应,这些化合物的浓度会引起发育畸形。在 24 和 48 hpf 时,通过全基因组微阵列分析 mRNA 表达,鉴定了随时间和对三种 PAH 结构差异调节的基因。在这两个时间点使用 GC-MS 分析 PAH 体负荷,证明了 PAH 进入胚胎的吸收存在差异。这对于辨别与代表独特分子机制的那些相关的剂量相关差异很重要。虽然 BAA 调节的转录本数量最少,但它强烈诱导了 cyp1a 和其他已知是 AHR 下游的基因,而其他两种 PAH 则没有诱导这些基因。对失调基因的功能作用及其预测的调节转录因子的分析也区分了 BAA 反应与 DBT 和 PYR 暴露破坏的调节网络。这些结果表明,系统方法可用于根据暴露后干扰的网络对 PAH 的毒性进行分类,并且可能为揭示复杂 PAH 混合物的毒性提供一种途径。