REGULATION OF MICROSOMAL HEMOPROTEINS

超出所提供的空间。 毒理学中一个尚未解决的重大问题，具有广泛的医学、经济、法律的和政治后果， 将高剂量外源性物质的试验结果外推至人类的不确定性， 实验室动物我们的拨款计划将利用分子和细胞生物学的进展来帮助定义 可能有助于宿主抵抗不利健康风险的遗传和环境因素 对特定个体的影响。我们关注的是CYP3A基因亚家族的细胞色素P450， 一组在“应激”条件下诱导的人肝脏中显著存在的微粒体血红素蛋白 糖皮质激素以及苯巴比妥和多卤代芳族化合物等异生物素 环境化学品。CYP3A参与临床重要药物的代谢， 环孢菌素和硝苯地平以及许多致癌物和环境污染物。以 分子生物学新技术的优势和良好定义的原代培养系统， 非增殖性成年啮齿类动物肝细胞，在培养中维持分化的肝功能，并允许 对调控CYP3A基因表达的功能性核心DNA元件进行分子分析，我们将 表征相关的配体依赖性调节转录蛋白因子。伴随着这 基础科学是我们对人类志愿者进行CYP3A诱导的临床方案 活动我们已经记录的大量变化可以部分追溯到一个 携带PXR家族的功能障碍受体等位基因。我们将确认这些发现并将其扩展到 定义这种和其他遗传差异的分布，这些差异可能导致诱导的变化， 因此，可能成为疾病的危险因素。我们还将使用反向遗传分析来研究一种 以前未被识别的基因分类，在相同的“压力”控制下调节， 超越药物代谢，甚至超越肝脏，可能共同适应环境 压力源通过临床和基础实验室方法的深思熟虑的结合，我们希望 能够定量描述细胞表达变化的分子事件， CYP3A基因由于药物、环境化学物质、内分泌控制等因素而翻译 将这些数据与人类的相关基因联系起来。我们完全期待对基因结构的理解， 基因表达和疾病结果可以通过所提出的研究计划来实现。

EXCEED THE SPACEPROVIDED. A major unsolved problem in toxicologyhaving broad medical, economic, legal, and political consequences is the uncertainty of extrapolation to humans of the results of tests of high doses of xenobiotics given to laboratory animals. Our grant proposal will utilize advances in molecular and cellular biology to help define the genetic and environmental factors that may contribute to host resistance to risks for an adverse health effect to a given individual. We are focusing on the cytochromes P450 of the CYP3A gene subfamily, a group of microsomal hemoproteins prominent in human liver which are induced under conditions of "stress" by glucocorticoids and also by such xenobiotics as phenobarbital, and polyhalogenated aromatic environmental chemicals. CYP3A are involved in the metabolism of clinically important drugs such as cyclosporin and nifedipine and also of numerous carcinogens and environmental pollutants. Taking advantage of new techniques in molecular biology and a well defined system for primary culture of nonproliferating adult rodent hepatocytes that maintain differentiated liver functions in culture and permit molecular analysis of functional core DNA elements that regulate CYP3A gene expression, we will characterize the relevant ligand dependent regulatory transcription protein factors. Accompanying this fundamental science is our clinical protocol to phenotype human volunteers for inducibility of CYP3A activity. The substantial variation we have already documented can be traced in part to hypoinduction in a carrier of a dysfunctional receptor allele of the PXRfamily. We will confirm and extend these findings to define the distribution of this and other genetic differences that may account for variation of induction and, hence, may serve as risk factors for disease. We will also use reverse genetic analysis to investigate a previously unrecognized assortment of genes, regulated under the same "stress" controls, that extends beyond drug metabolism and even beyond the liver, possibly acting in concert to adapt to environmental stressors. Through a thoughtful combination of clinical and basic laboratory approaches, we expect to be able to quantitatively describe the molecular events that underlie changes in cellular expression of the CYP3A genes due to drugs, environmental chemicals, endocrine controls and other factors and to translate these data to the relevant genes in humans. We fully expect that refinements in understanding gene structure, gene expression, and disease outcome can be achieved by the proposed research program.