Pharmacogenetics of ADRs: Warfarin Toxicity

这项研究的长期目标是了解人类基因变异是如何 会影响药物毒性。在这次续期申请中，我们将继续努力 阐明口服抗凝剂不良反应的潜在机制， 特别是香豆素类药物华法林，每天有200多万人服用 美国人，并且仍然是急诊室就诊的最常见原因之一 因为有不良反应。在前一个供资期间，重点主要放在 细胞色素P450酶，CYP2C9的遗传变异，因为它控制 消旋药物中效力更强的(S)对映体的代谢清除。然而， 在之前的授权期内，华法林靶蛋白的基因-VKORC1- 已被克隆，并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)肝脏表达和，2)华法林结合位点的基本性质(S) 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)使用报告基因构建的VKORC1基因座的多态，定点定向 诱变和DNA/蛋白质结合试验。 具体目标2：在两个配体的水平上确定结构-活性关系 和VKOR可逆和不可逆抑制的蛋白质使用一组 结构多样的维生素K拮抗剂及其新的模型 膜结合酶。 由于拟议研究的范围很广，这项建议将 西雅图和密尔沃基表演场地的调查人员正在努力解决这些问题。 这些研究的成功完成将增加我们对基本知识的了解 (I)VKORC1基因多态影响患者服药剂量的机制 华法林和(Ii)华法林抑制维生素K循环。

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.