Senft Albert P, Dalton Timothy P, Nebert Daniel W, Genter Mary Beth, Puga Alvaro, Hutchinson Richard J, Kerzee J Kevin, Uno Shigeyuki, Shertzer Howard G
Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati Medical Center, OH 45267, USA.
Free Radic Biol Med. 2002 Nov 1;33(9):1268-78. doi: 10.1016/s0891-5849(02)01014-6.
2,3,7,8-Tetrachlorodibenzo-p-dioxin (dioxin; TCDD) is a pervasive environmental contaminant that induces hepatic and extrahepatic oxidative stress. We have previously shown that dioxin increases mitochondrial respiration-dependent reactive oxygen production. In the present study we examined the dependence of mitochondrial reactive oxygen production on the aromatic hydrocarbon receptor (AHR), cytochrome P450 1A1 (CYP1A1), and cytochrome P450 1A2 (CYP1A2), proteins believed to be important in dioxin-induced liver toxicity. Congenic Ahr(-/-), Cyp1a1(-/-) and Cyp1a2(-/-) knockout mice, and C57BL/6J inbred mice as their Ahr/Cyp1a1/Cyp1a2(+/+) wild-type (wt) counterparts, were injected intraperitoneally with dioxin (15 microg/kg body weight) or corn-oil vehicle on 3 consecutive days. Liver mitochondria were examined 1 week following the first treatment. The level of mitochondrial H(2)O(2) production in vehicle-treated Ahr(-/-) mice was one fifth that found in vehicle-treated wt mice. Whereas dioxin caused a rise in succinate-stimulated mitochondrial H(2)O(2) production in the wt, Cyp1a1(-/-), and Cyp1a2(-/-) mice, this increase did not occur with the Ahr(-/-) knockout. The lack of H(2)O(2) production in Ahr(-/-) mice was not due to low levels of Mn(2+)-superoxide dismutase (SOD2) as shown by Western immunoblot analysis, nor was it due to high levels of mitochondrial glutathione peroxidase (GPX1) activity. Dioxin decreased mitochondrial aconitase (an enzyme inactivated by superoxide) by 44% in wt mice, by 26% in Cyp1a2(-/-) mice, and by 24% in Cyp1a1(-/-) mice; no change was observed in Ahr(-/-) mice. Dioxin treatment increased mitochondrial glutathione levels in the wt, Cyp1a1(-/-), and Cyp1a2(-/-) mice, but not in Ahr(-/-) mice. These results suggest that both constitutive and dioxin-induced mitochondrial reactive oxygen production is associated with a function of the AHR, and these effects are independent of either CYP1A1 or CYP1A2.
2,3,7,8-四氯二苯并对二恶英（二恶英；TCDD）是一种普遍存在的环境污染物，可诱导肝脏和肝外氧化应激。我们之前已经表明，二恶英会增加线粒体呼吸依赖性活性氧的产生。在本研究中，我们研究了线粒体活性氧产生对芳烃受体（AHR）、细胞色素P450 1A1（CYP1A1）和细胞色素P450 1A2（CYP1A2）的依赖性，这些蛋白质被认为在二恶英诱导的肝毒性中起重要作用。将同基因的Ahr(-/-)、Cyp1a1(-/-)和Cyp1a2(-/-)基因敲除小鼠，以及作为其Ahr/Cyp1a1/Cyp1a2(+/+)野生型（wt）对照的C57BL/6J近交系小鼠，连续3天腹腔注射二恶英（15微克/千克体重）或玉米油载体。在首次治疗后1周检查肝脏线粒体。在接受载体处理的Ahr(-/-)小鼠中，线粒体H(2)O(2)的产生水平是接受载体处理的wt小鼠的五分之一。虽然二恶英导致wt、Cyp1a1(-/-)和Cyp1a2(-/-)小鼠中琥珀酸刺激的线粒体H(2)O(2)产生增加，但Ahr(-/-)基因敲除小鼠未出现这种增加。如Western免疫印迹分析所示，Ahr(-/-)小鼠中缺乏H(2)O(2)产生并非由于锰(2+)-超氧化物歧化酶（SOD2）水平低，也不是由于线粒体谷胱甘肽过氧化物酶（GPX1）活性高。二恶英使wt小鼠中线粒体乌头酸酶（一种被超氧化物灭活的酶）降低44%，使Cyp1a2(-/-)小鼠降低26%，使Cyp1a1(-/-)小鼠降低24%；在Ahr(-/-)小鼠中未观察到变化。二恶英处理使wt、Cyp1a1(-/-)和Cyp1a2(-/-)小鼠中的线粒体谷胱甘肽水平升高，但在Ahr(-/-)小鼠中未升高。这些结果表明，组成型和二恶英诱导的线粒体活性氧产生均与AHR的功能相关，且这些效应独立于CYP1A1或CYP1A2。
