Induction of cytochrome P4501A1 by photooxidized tryptophan in Hepa lclc7 cells.
Induction of cytochrome P4501A1 by photooxidized tryptophan in Hepa lclc7 cells.
复制标题
Hepa lclc7 细胞中光氧化色氨酸诱导细胞色素 P4501A1。
DOI：
10.1016/s0006-2952(97)81491-8
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发表时间：
1996
影响因子：
5.8
通讯作者：
Kikkawa,Y
中科院分区：
文献类型：
--
作者：
Sindhu,RK;Reisz-Porszasz,S;Hankinson,O;Kikkawa,Y
小鼠肝癌HEPA-LCLC？(HEPA-1)细胞在紫外线照射的氨基酸存在下培养。结果表明，紫外光氧化的色氨酸诱导的7-乙氧基间苯二酚O-脱乙基酶(EROD)活性最高(P<；0.01)。氧化色氨酸对EROD活性的诱导具有剂量依赖性，在给药后12小时达到最大。对不同的HEPA-1突变体的研究表明，氧化色氨酸通过AH受体诱导EROD活性，这些突变体在芳香烃(Ah)受体或ah受体核转位蛋白中存在缺陷。用HEPA-1细胞的核提取液进行凝胶迁移率改变分析表明，色氨酸的氧化产物既能诱导ah受体的转化，又能与其特定的DNA识别位点结合。经逆转录-聚合酶链式反应检测，氧化色氨酸组与对照组相比，细胞色素P4501A1m RNA和蛋白表达显著增加。与对照组相比，成年雄性大鼠注射分离的氧化色氨酸产物可显著诱导肺和肝微粒体EROD活性(P<；0.01)。这些结果表明，氧化的色氨酸诱导了Ah受体的激活，并将连接的Ah受体复合体与其特定的DNA识别位点结合，从而启动了CYP1A1基因的转录和翻译，同时伴随着HEPA-1细胞中erod活性的增加。在大鼠体内注射单独的氧化色氨酸产物后，肝脏和肺中EROD活性的诱导表明，类似的机制可能在体内操作。
Mouse hepatoma Hepa-lclc? (Hepa-1) cells were cultivated in the presence of UV-irradiated amino acids. The results demonstrated that all of the amino acids tested, UV-oxidized tryptophan caused the highest induction of 7-ethoxyresorufin O-deethylase (EROD) activity compared with the controls (P < 0.01). The induction of EROD activity by oxidized tryptophan was dose dependent, and maximal induction was obtained at 12 hr after administration. Studies with various Hepa-1 mutants, which are defective in either the aryl hydrocarbon (Ah) receptor or Ah receptor nuclear translocator protein, indicated that the induction of EROD activity by oxidized tryptophan occurs through the Ah receptor. Gel mobility shift assays using nuclear extracts of Hepa-1 cells revealed that oxidized products of tryptophan can induce both Ah receptor transformation and binding of the liganded Ah receptor complex to its specific DNA recognition site. CYP1A1 mRNA, quantified by reverse transcription-polymerase chain reaction, and CYP1A1 protein were induced markedly in the oxidized tryptophan group compared with the controls. Injection of isolated oxidized tryptophan products into adult male rats caused significant induction of EROD activity in the pulmonary and hepatic microsomes compared with the controls (P < 0.01). These results demonstrated that oxidized tryptophan induces Ah receptor activation and binding of the liganded Ah receptor complex to its specific DNA recognition site, thereby initiating transcription and translation of the CYP1A1 gene with concomitant increase of EROD activity in Hepa-1 cells. Induction of EROD activity in the liver and lungs after injection of isolated oxidized tryptophan products into rats suggests that a similar mechanism may be operative in vivo.