DRUG METABOLIZING ENZYMES IN ANIMAL MODELS AND HUMAN TISSUE

动物模型和人体组织中的药物代谢酶

• 批准号: 3941465
• 负责人: J A GOLDSTEIN
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF ENVIRONMENTAL HEALTH SCIENCES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3941465
• 关键词: biological polymorphism; complementary DNA; cytochrome P450; detoxification; drug metabolism; gene expression; genetic library; genetic manipulation; human tissue; isozymes; liver metabolism; messenger RNA; microsomes; oxygenases; toxin; toxin metabolism

This project is new so the summary of work represent plans, objectives and some preliminary findings. Cytochrome P-450 is the principal monooxygenase system which catalyzes foreign chemicals to mutagens and carcinogens as well as inactivating them. This system is perturbed dramatically by exposure to hormones and foreign chemicals. The system consists of a large number of isozymes each with its own substrate specificity. Some P-450 enzymes are constitutive and some appear to be polymorphic (present or absent, active or inactive) in outbred strains of rats and in man. The polymorphisms can result in dramatic differences in the ability to metabolize certain drugs (e.g., a polymorphism for debrisoquine metabolism and sparteine metabolism in man). Antibodies and cDNA probes to the P-450 proteins are useful for determining the effects of chemicals on these enzymes and for studying polymorphisms in these enzymes. One objective of these studies is to examine phenotypic variability of P-450g, a constitutive enzyme, in male rats and humans. Our data suggest that the CD rat is a good model to study polymorphism of this cytochrome in humans. These studies revealed that rats could be divided into two distinct phenotypes containing high P-450g (10-20% of total P-450) or low P-450g (greater than 0.5%). Surprisingly, both phenotypes of male rats appeared to contain a translatable mRNA for this enzyme although it was absent in females suggesting that the defect might be defective or labile enzyme in the low phenotype. P-450g was shown to metabolize aflatoxin to mutagens in a reconstituted system. A cDNA library was constructed from high phenotype P- 450g in rats, and several putative cDNA clones for this protein have been selected with antibody and rescreening with a positive clone. If human tissue is available, we plan to analyze the DNA by Southern blots and restriction analysis to determine whether the phenotypic variability in one or more human P-450s is associated with liver or lung tumors.

这个项目是新的，所以工作总结代表计划， 目标和一些初步调查结果。 细胞色素P-450 主要单加氧酶系统催化外源 化学品致突变剂和致癌物质以及灭活 他们 这个系统被暴露在 荷尔蒙和外来化学物质 该系统由一个大型 同工酶的数量，每个都有自己的底物特异性。 一些 P-450酶是组成型的，有些似乎是 多态性（存在或不存在，活跃或不活跃）在远交 在大鼠和人类中。多态性可以导致 代谢某些药物的能力 (e.g.,异喹胍代谢和鹰爪豆碱的多态性 人的新陈代谢）。 针对P-450的抗体和cDNA探针 蛋白质可用于确定化学物质对 这些酶和研究这些酶的多态性。 这些研究的一个目的是检查表型 雄性大鼠中组成酶P-450 g的变异性， 人类 我们的数据表明，CD大鼠是一个很好的模型， 研究这种细胞色素在人类中多态性。 这些研究 显示大鼠可以分为两种不同的表型 含有高P-450 g（占总P-450的10-20%）或低P-450 g （大于0.5%）。 令人惊讶的是，雄性大鼠的两种表型 似乎含有这种酶的可翻译mRNA 但在雌性中没有，这表明 在低表型中可能是有缺陷的或不稳定的酶。 P-450g 在重组的 系统 从高表型P- 450 g，以及该蛋白的几个推定cDNA克隆 已被抗体筛选，并重新筛选阳性 分身 如果有人体组织，我们计划分析DNA 通过Southern印迹和限制性分析来确定是否 一个或多个人P-450的表型变异性是 与肝或肺肿瘤有关。