PHARMACOGENETICS OF PHASE II DRUG METABOLIZING ENZYMES

药物遗传学是研究遗传在药物反应个体差异中的作用的学科。迄今为止研究的大多数药物遗传变异都涉及药物代谢的个体变异。参与药物代谢的反应分为“第一阶段”和“第二阶段”。II期药物代谢包括偶联反应，20多年来，梅奥药物遗传学研究项目对II期药物代谢途径遗传变异的生化、分子和基因组基础的理解做出了贡献。本申请建议在此基础上利用分子药物遗传学和人类基因组学方面的进展汇合，确定并向生物医学研究界提供关于共同的、单核苷酸多态性（SNPs）以及基因内的插入/缺失事件，这些基因编码蛋白质，催化人类药物代谢的II期途径-特别强调那些催化甲基和硫酸盐偶联的酶。然而，该提案不仅仅是快速提供II期药物代谢酶基因中常见序列变异的数据，还包括旨在确定这些常见遗传多态性导致的编码氨基酸序列遗传改变的功能意义的研究。由于氨基酸序列在功能上的显著变化可以潜在地改变酶的催化特性，或者，正如已经发现的越来越普遍的那样，它们可以改变酶蛋白的水平，提议的功能基因组研究将集中在这两种可能性上。他们还将包括对选定蛋白质进行基于同源性的结构建模，以尝试验证一种假设，即有可能预测II期酶编码氨基酸序列遗传改变的功能后果。因此，这种综合方法将结合遗传核苷酸序列变异的测定、改变编码氨基酸的基因序列变异的功能后果、基于同源性的结构建模，最后，它还将包括对SNP和插入/删除检测的高通量分析技术的评估，这些技术可能应用于临床研究环境。因此，有可能应用药物遗传信息来检验关于药物反应的个体差异的医学相关假设。综上所述，建议对II期药物代谢酶进行全面、综合的药物基因组学和药物遗传学研究，特别强调甲基转移酶和硫转移酶。

Pharmacogenetics is the study of the role of inheritance in individual variation in drug response. Most pharmacogenetic variation that has been studied to this time involves individual variation in drug metabolism. Reactions involved in the metabolism of drugs are classified as either "phase I" or "phase II". Phase II drug metabolism includes conjugation reactions, and for over 20 years the Mayo pharmacogenetics research program has contributed to understanding of the biochemical, molecular and genomic basis for inherited variations in phase II pathways of drug metabolism. The present application proposes to build on that foundation to take advantage of the convergence of advances in molecular pharmacogenetics and human genomics to determine and make available to the biomedical research community information with regard to common, single nucleotide polymorphisms (SNPs) as well as insertion/deletion events within genes that encode proteins that catalyze phase II pathways of drug metabolism in humans -- with special emphasis on those enzymes that catalyze methyl and sulfate conjugation. However, the proposal goes beyond merely rapidly providing data on common sequence variations in genes for phase II drug-metabolizing enzymes to also include studies designed to determine the functional significance of inherited alterations in encoded amino acid sequence that result from these common genetic polymorphisms. Since functionally significant variations in amino acid sequence can potentially alter either the catalytic properties of an enzyme or, as has been found to be increasingly common, they can alter the level of enzyme protein, the proposed functional genomic studies will focus on these two possibilities. They will also include homology-based structural modeling for selected proteins in an attempt to test the hypothesis that it may be possible to predict the functional consequences of inherited alteration in encoded amino acid sequence for phase II enzymes. Therefore, this integrated approach will combine determinations of inherited nucleotide sequence variation, the functional consequences of gene sequence variation that alters encoded amino acids, homology-based structural modeling, and -- finally -- it will also include the evaluation of high throughput analytical techniques for SNP and insertion/deletion detection that could potentially be applied in a clinical research setting, thus making it possible to apply pharmacogenetic information to test medically relevant hypotheses with regard to individual variations in drug response. In summary, a comprehensive, integrated program of pharmacogenomic and pharmacogenetic studies of phase II drug-metabolizing enzymes, with special emphasis on methyltransferase and sulfotransferase enzymes, is proposed.