TOXICOLOGICAL CONTROL MECHANISMS OF HUMAN CYP1A2 GENE

包括多环化合物在内的化学类异生物质的毒性 芳香烃（PAH）和卤代烃，如 多氯联苯和二苯并二恶英，最有可能通过 控制基因表达。其分子机制在很大程度上是未知的， 但目前认为部分涉及胞质受体， 芳香烃或AH-受体。如果负责许多人的机制 与这些类别的化学品相关的毒性作用将被 解开，将有必要研究其他基因， 通过额外的细胞介质。本补助金提案的重点是 人细胞色素P4501A2基因（CYP1A2），PAH诱导的 CYP1A基因家族是人类肝脏中的重要基因，与药物代谢有关， 如对乙酰氨基酚、咖啡因、环境试剂如芳胺 和膳食成分，如杂环胺和黄曲霉毒素。的 调控人CYP1A2基因的分子机制将是 通过顺式作用元件的表征进行研究， 利用瞬时转染鉴定反式作用因子 测定和体外DNA结合测定，如DNA酶I足迹法。在 将在人原代肝细胞中进行体内足迹研究 研究转录因子之间的时间关系， 调节CYP1A2基因表达。将使用几个模型系统 对于拟议的研究，包括人类肝癌细胞系，人类 肝和人肝细胞的非增殖培养物。细胞培养 核心和人体组织库将提供必要的支持， 问题研究据信，这些分子和细胞的组合 文化的方法将阐明这一重要的机制， 基因被调控。

Toxicity of the chemical class of xenobiotics that include polycyclic aromatic hydrocarbons (PAH) and halogenated hydrocarbons, such as polychlorinated biphenyls and dibenzodioxins, most likely occurs through control of gene expression. The molecular mechanism is largely unknown, but is currently believed to involve, In part, a cytosolic receptor, the aryl hydrocarbon or Ah-receptor. If the mechanism responsible for the many toxic effects associated with these classes of chemicals is to be unraveled, it will be necessary to study other genes that may be regulated through additional cellular mediators. This grant proposal focuses on the human cytochrome P4501A2 gene (CYP1A2), a member of the PAH-inducible CYP1A gene family that is prominent in human liver, and metabolizes drugs, such as acetaminophen, caffeine, environmental agents such as arylamines and dietary constituents, such as heterocyclic amines and aflatoxins. The molecular mechanism for the regulation of the human CYP1A2 gene will be studied through the characterization of cis-acting elements and identification of trans-acting factors utilizing transient transfection assays and in vitro DNA binding assays, such as DNase I footprinting. In vivo footprinting studies in human primary hepatocytes will be conducted to examine the temporal relationship among transcription factors in regulating CYP1A2 gene expression. Several model systems will be utilized for the proposed research, including human hepatoma cell lines, human liver and non-proliferating cultures of human hepatocytes. A Cell Culture Core and Human Tissue Bank will provide the necessary support for these studies. It is believed that a combination of these molecular and cell culture approaches will elucidate the mechanism by which this important gene is regulated.