Jiang Tao, Bell David R, Clode Sally, Fan Ming Qi, Fernandes Alwyn, Foster Paul M D, Loizou George, MacNicoll Alan, Miller Brian G, Rose Martin, Tran Lang, White Shaun
School of Biology, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
Toxicol Sci. 2009 Feb;107(2):512-21. doi: 10.1093/toxsci/kfn252. Epub 2008 Dec 4.
The aryl hydrocarbon receptor (AhR) is required for the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and so the AhR of CRL:WI and CRL:WI(Han) rats was characterized. Western blot showed AhR proteins of approximately 110 and approximately 97 kDa in individual rats from both strains. The AhR cDNA from a CRL:WI(Han) rat with the approximately 110-kDa protein revealed a sequence that was identical to that of the CRL:WI and SD rat. However, cloning of the AhR from a rat with the approximately 97-kDa protein revealed a point mutation, and five variants encoding two C-terminally truncated variants of the AhR protein, arising from a point mutation in the intron/exon junction and consequent differential splicing. These C-terminally truncated variants were expressed and shown to give rise to a protein of approximately 97 kDa; the recombinant AhR bound TCDD with an affinity that was not statistically different from the full-length protein. A single-nucleotide polymorphism assay was developed, and showed that both alleles were represented in a Hardy-Weinberg equilibrium in samples of CRL:WI and CRL:WI(Han) populations; both alleles are abundant. Rats from two studies of TCDD developmental toxicity were genotyped, and the association with toxicity investigated using statistical analysis. There was no plausible evidence that the AhR allele had a significant effect on the toxic endpoints examined. These data show that the two AhR alleles are common in two strains of Wistar rat, and that the AhR alleles had no effect on TCDD-induced developmental toxicity in two independent studies.
芳烃受体（AhR）是2,3,7,8-四氯二苯并对二恶英（TCDD）产生毒性所必需的，因此对CRL:WI和CRL:WI（Han）大鼠的AhR进行了特性分析。蛋白质免疫印迹显示，这两个品系的个体大鼠中AhR蛋白的分子量分别约为110 kDa和97 kDa。来自一只具有约110 kDa蛋白的CRL:WI（Han）大鼠的AhR cDNA显示其序列与CRL:WI和SD大鼠的相同。然而，从一只具有约97 kDa蛋白的大鼠中克隆AhR时发现了一个点突变，该突变导致了五个变体，编码两种AhR蛋白C末端截短的变体，这是由于内含子/外显子连接处的点突变以及随后的可变剪接引起的。这些C末端截短的变体被表达，并显示产生一种约97 kDa的蛋白；重组AhR与TCDD结合的亲和力与全长蛋白相比无统计学差异。开发了一种单核苷酸多态性检测方法，结果显示在CRL:WI和CRL:WI（Han）种群样本中，两个等位基因均处于哈迪-温伯格平衡状态；两个等位基因都很常见。对两项关于TCDD发育毒性研究中的大鼠进行了基因分型，并通过统计分析研究了其与毒性的关联。没有合理的证据表明AhR等位基因对所检测的毒性终点有显著影响。这些数据表明，两种AhR等位基因在两种Wistar大鼠品系中很常见，并且在两项独立研究中，AhR等位基因对TCDD诱导的发育毒性没有影响。
