REGULATION OF ETHANOL INDUCIBLE CYTOCHROME P450 2E1 (CYP2E1)

我们先前已经分离了编码该基因的cdna和基因组克隆。 乙醇诱导的细胞色素P450IIE1，并证明了六种不同的 对其表达的调控类型。在过去的一年里，我们已经 继续研究一种实验性抗肝硬变的效果 YH439，并进一步表征了P450IIE1的一种新机制 受外源化合物YH439的调控。P450IIE1活性和 YH439在一段时间内有效地抑制了蛋白质水平-并且 呈剂量依赖方式。核连续转录分析证实 YH439最早抑制P450IIE1基因转录2小时 后YH439管理。相比之下，P450IA1/2基因是 YH439诱导转录。以阐明其发病机制。 YH439的转录调控、P4502E1和P4502E1启动子区域 正在积极研究P4501A1/2基因的阴性和阳性 元素。我们已经证明了YH439激活了P450IA1/2 人肝癌细胞系HepG2中的基因。在这个细胞系中， YH439激活芳香烃受体(ah受体)， 以前被证明调节二恶英的毒性效应以及其他 环境污染物。我们之前已经发布了P450IIE1 在怀孕期间被翻译前被抑制，然后它又回来了 在分娩后1天内恢复到正常水平。我们还有 探讨其他P450蛋白在妊娠过程中的表达及其意义 基因表达的机制。核连续转录分析 揭示了P450IIE1和其他P450基因主要在 转录后水平。与罗伯茨博士和 Shoaf、P450IIE1及其他同工酶在肝、脑、肺组织中的表达水平。 以及其他组织在饮酒期间和饮酒后的研究 戒酒期。酒精使P450IIE1水平升高 在所有被检查的组织中增加5倍。戒酒后，P450IIE1 水平迅速(12小时内)恢复到正常水平，支持 我们早先关于P450IIE1和它的半衰期相对较短的报告 蛋白质由乙醇和丙酮稳定。P450IIE1稳定器 乙醇介导的P450IIE1偶联干扰 泛素，使P450IIE1迅速降解。

We have previously isolated both the cDNA and genomic clones encoding the ethanol-inducible cytochrome P450IIE1 and have demonstrated six distinct types of regulation of its expression. During the past year, we have continued to investigate the effect of an experimental anti-cirrhotic agent YH439 and have further characterized a novel mechanism of P450IIE1 regulation by an exogenous compound, YH439. P450IIE1 activity and protein level were effectively suppressed by YH439 in a time- and dose-dependent manner. Nuclear run-on transcription assays confirmed that YH439 inhibited transcription of P450IIE1 gene as early as two hours post-YH439 administration. In contrast, P450IA1/2 genes were transcriptionally induced by YH439. To elucidate the mechanisms of the transcriptional regulations by YH439, the promoter regions of P4502E1 and P4501A1/2 genes are being actively studied for negative and positive elements, respectively. We have shown that YH439 activates the P450IA1/2 genes in the human hepatocarcinoma cell line, HepG2. In this cell line, YH439 activates the aromatic hydrocarbon receptor (Ah receptor), previously shown to mediate the toxic effects of dioxine as well as other environmental contaminants. We have previously published that P450IIE1 was pretranslationally suppressed during pregnancy and that it returned to normal level (within 1 day) upon parturition. We have also investigated the expression of other P450s during pregnancy and their mechanism of gene expression. Nuclear run-on transcription analyses revealed that P450IIE1 and other P450 genes are mainly regulated at the post-transcriptional level. In collaboration with Drs. Roberts and Shoaf, the levels of P450IIE1 and other P450 isoenzymes in liver, brain, and other tissues were studied during alcohol consumption and after alcohol withdrawal period. Alcohol elevated the levels of P450IIE1 5-fold in all tissues examined. After withdrawal of alcohol, P450IIE1 level rapidly (within 12 hours) returned to the normal level, supporting our earlier report on the relatively short half-lives of P450IIE1 and its protein stabilization by ethanol and acetone. The P450IIE1 stabilization by ethanol was mediated by interference of the conjugation of P450IIE1 with ubiquitin, which renders rapid degradation of P450IIE1.