Pharmacogenetics of ADRs: Warfarin Toxicity

这项研究的长期目标是了解人类遗传变异是如何 影响药物毒性。在这次续约申请中，我们将继续努力， 阐明口服抗凝剂药物不良反应的潜在机制， 特别是香豆素类药物华法林，每天有超过200万人服用 美国人，仍然是最常见的原因之一，急诊室访问 因为不良反应。在上一个供资期间，重点主要是 细胞色素P450酶CYP 2C 9内的遗传变异，因为它控制着 外消旋药物的更有效的（S）对映体的代谢清除。然而，在这方面， 在前一个授予期，华法林靶蛋白基因-VKORC 1- 已成为此应用程序的新焦点，因为它控制 对药物的药效学反应。在本申请中，我们试图 了解; 1）影响维生素K环氧化物还原酶的调节机制 （VKOR）肝脏表达，2）华法林结合位点的基本性质 在VKOR。为了实现这些目标，我们制定了以下目标： 具体目标1：确定调控（启动子和 内含子）多态性，使用报告构建体，定点 诱变和DNA/蛋白质结合测定。 具体目标2：在配体水平上定义结构-活性关系 以及使用一组用于可逆和不可逆抑制VKOR的蛋白质， 结构多样的维生素K拮抗剂以及这种结构的新模型 膜结合酶 由于拟议的研究范围广泛，本提案汇集了 在西雅图和密尔沃基的演出现场的调查人员来研究这些问题。 这些研究的成功完成将增加我们的基本知识， （i）VKORC 1基因多态性影响患者给药的机制 华法林和（ii）维生素K循环被华法林抑制。

The long-term aim of this research is to understand how human genetic variation influences drug toxicity. In this renewal application, we will continue our efforts to elucidate mechanisms underlying adverse drug reactions to oral anticoagulants, specifically the coumarin drug, warfarin, which is taken daily by over 2 million Americans, and remains one of the most common causes of emergency room visits because of adverse reactions. In the previous funding period the focus was primarily on genetic variation within the cytochrome P450 enzyme, CYP2C9, because it controls metabolic clearance of the more potent (S) enantiomer of the racemic drug. However, during the previous granting period the gene for the warfarin target protein - VKORC1 - was cloned and has become the new focus of this application because it controls the pharmacodynamic response to the drug. In the present application we are attempting to understand; 1) regulatory mechanisms that influence vitamin K epoxide reductase (VKOR) hepatic expression and, 2) the fundamental nature of the warfarin binding site(s) in VKOR. To address these goals we have formulated the following aims: Specific Aim 1: Determine the functional significance of regulatory (promoter and intronic) polymorphisms at the VKORC1 locus using reporter constructs, site-directed mutagenesis and DNA/protein binding assays. Specific Aim 2: Define structure-activity relationships at the level of both the ligand and the protein for reversible and irreversible inhibition of VKOR using a set of structurally diverse vitamin K antagonists together with novel modeling of this membrane-bound enzyme. Due to the broad scope of the proposed research, this proposal brings together investigators at performance sites in Seattle and Milwaukee to work on these problems. Successful completion of these studies will add to our knowledge of the fundamental mechanisms by which; (i) polymorphisms in the VKORC1 gene affect patient dosing with warfarin and (ii) the vitamin K cycle is inhibited by warfarin.