REGULATION OF MICROSOMAL HEMOPROTEINS

超过SPACEPROVIDED 毒物学中一个尚未解决的重大问题具有广泛的医疗、经济、法律和政治后果 大剂量异物给药试验结果对人体外推的不确定度 实验动物。我们的资助计划将利用分子和细胞生物学的进步来帮助定义 可能导致宿主对有害健康风险产生抵抗力的遗传和环境因素 对某一特定个人的影响。我们关注的是CYP3A基因亚家族的细胞色素P450， 在“应激”条件下诱导的人体肝脏中显著的一组微粒体血球蛋白。 由糖皮质激素以及苯巴比妥和多卤代芳香族等外来生物所致 环境化学品。细胞色素P3A参与临床重要药物的代谢，如 环孢素和硝苯地平，以及多种致癌物质和环境污染物。拿走 分子生物学新技术的优势和完善的原代培养体系 非增殖性成年啮齿动物肝细胞在培养和允许的情况下保持分化的肝功能 对调控CYP3A基因表达的功能核心DNA元件的分子分析，我们将 鉴定相关的配体依赖的调节转录蛋白因子。伴随而来的是 基础科学是我们的临床方案，以表型人类志愿者为诱导性的CYP3A 活动。我们已经记录的实质性变化可以部分追溯到在一个 PXR家族功能失调的受体等位基因携带者。我们将确认这些调查结果并将其扩展到 定义这种遗传差异和其他可能导致诱导变异的遗传差异的分布， 因此，可能会成为疾病的危险因素。我们还将使用反向遗传分析来调查 以前未被识别的基因分类，在相同的“压力”控制下被调节，扩展 超越药物代谢，甚至超越肝脏，可能协同行动以适应环境 压力源。通过深思熟虑地结合临床和基础实验室方法，我们希望 能够定量地描述导致细胞表达变化的分子事件 CYP3A基因受药物、环境化学物质、内分泌控制等因素的影响及翻译 这些数据与人类的相关基因有关。我们完全期待在理解基因结构方面的改进， 通过拟议的研究计划，可以实现基因表达和疾病结局。

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.