Catalysis by Prostaglandin Endoperoxide H Synthases

前列腺素内过氧化物 H 合成酶的催化作用

• 批准号: 8469864
• 负责人: William L Smith
• 金额: $ 45.41万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-01 至 2015-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8469864
• 关键词: Adverse drug effect; Adverse effects; Affect; Allosteric Regulation; Amino Acid Sequence; Anabolism; Analgesics; Animals; Anti Inflammatory Analgesics; Arachidonic Acids; Aspirin; Binding; Biochemical; Blood Platelets; Blood Vessels; Cardiac; Cardiovascular system; Catalysis; Cells; Cessation of life; Colon Carcinoma; Commit; Coxibs; Crystallography; Culture Media; Cyclooxygenase Inhibitors; Diclofenac; Diet; Diet Habits; Dietary Fats; Dinoprostone; Eicosapentaenoic Acid; Environment; Enzymes; Epoprostenol; Event; Exhibits; Fatty Acids; Fatty acid glycerol esters; Fibroblasts; Fish Oils; Flurbiprofen; Functional disorder; Genetic; Goals; Human; Ibuprofen; Individual; Inflammation; Inflammatory; Kidney; Lead; Linoleic Acids; Measurement; Measures; Mediating; Molecular; Molecular Conformation; Monounsaturated Fatty Acids; Mus; Naproxen; Non-Steroidal Anti-Inflammatory Agents; Nonesterified Fatty Acids; Oleic Acids; PTGS1 gene; PTGS2 gene; Palmitic Acids; Pharmaceutical Preparations; Pharmacologic Substance; Phospholipids; Physiological; Prostaglandin Endoperoxides; Prostaglandin H2; Prostaglandin Production; Prostaglandins; Prostaglandins I; Protein Isoforms; Public Health; Regulation; Relative (related person); Research; Risk; Saturated Fatty Acids; Stearic Acids; Structure; System; Thromboxane A2; United States National Institutes of Health; Zymosan; adverse outcome; base; celecoxib; clinically relevant; cyclooxygenase 1; dimer; feeding; gastrointestinal; in vivo; inhibitor/antagonist; monomer; overexpression; preference; response; urinary

DESCRIPTION (provided by applicant): Prostaglandin endoperoxide H synthases-1 and -2 (PGHS-1 and -2), also known as cyclooxygenases-1 and -2 (COX-1 and COX-2), catalyze the conversion of arachidonic acid (AA) to prostaglandin H2 (PGH2) in the committed step of prostaglandin (PG) biosynthesis. PGHSs are the primary targets of COX inhibitors, which include nonspecific nonsteroidal anti-inflammatory drugs (nsNSAIDs) and COX-2 specific inhibitors called coxibs. COX inhibitors are the most widely used pharmaceutical agents in the U.S. However, the use of these inhibitors carries significant risks. About 20,000 deaths annually are attributable to adverse effects of these drugs, the molecular basis for which is unknown. Using purified human PGHSs, we have discovered that PGHS activities are modulated through an unusual allosteric mechanism by all common fatty acids (FAs) including those that are not PGHS substrates. FAs can stimulate or inhibit PGHS activity with the specific effect being dependent on the PGHS isoform and the FA. The effects occur at physiologic FA concentrations and are observed in cells as well as with purified enzymes. The biochemical basis for the regulation of PGHSs by FAs involves cross-talk between monomers comprising PGHS homodimers. Although the monomers have identical amino acid sequences, the conformations of the two monomers comprising a PGHS homodimer differ. One monomer binds FAs and behaves as an allosteric monomer while the other acts as the catalytic monomer. Finally and importantly, responses of purified human PGHSs to COX inhibitors are modulated by FAs, again depending on the FA, the inhibitor and the PGHS isoform. With different COX inhibitors, FAs can influence binding of an inhibitor to one or to both monomers. The goals of the proposed research are to determine how PGHSs and their responses to widely used COX inhibitors are affected by FAs at the molecular, cellular and whole animal levels. Our underlying hypothesis is that both in vivo PG production and responses to COX inhibitors are significantly modulated by the milieu of FAs in which the enzymes find themselves-the FA tone--and that this FA environment is importantly influenced by the FA composition of the diet. We presume that every individual establishes a FA tone as a consequence of dietary habits in the context of their genetic background. We speculate that certain FA tones predispose susceptible individuals to adverse consequences of COX inhibitors. We expect that our studies delineating FA/COX inhibitor interactions will be a first step leading to changes in the way COX inhibitors are prescribed to people on different diets and to dietary adjustments to provide for the safer use of COX inhibitors.

描述（申请人提供）：前列腺素内过氧化物H合酶-1和-2（PGHS-1和-2），也称为环加氧酶-1和-2（COX-1和COX-2），催化花生四烯酸的转化(AA) 在前列腺素 (PG) 生物合成的关键步骤中转化为前列腺素 H2 (PGH2)。 PGHS 是 COX 抑制剂的主要靶点，其中包括非特异性非甾体类抗炎药 (nsNSAID) 和称为昔布 (coxib) 的 COX-2 特异性抑制剂。 COX 抑制剂是美国使用最广泛的药剂。然而，使用这些抑制剂会带来巨大的风险。每年约有 20,000 人死亡归因于这些药物的不良反应，其分子基础尚不清楚。 使用纯化的人类 PGHS，我们发现 PGHS 活性通过一种不寻常的变构机制受到所有常见脂肪酸 (FA) 的调节，包括那些不是 PGHS 底物的脂肪酸。 FA 可以刺激或抑制 PGHS 活性，具体效果取决于 PGHS 亚型和 FA。这种效应在 FA 生理浓度下发生，并且可以在细胞以及纯化的酶中观察到。 FA 调节 PGHS 的生化基础涉及包含 PGHS 同二聚体的单体之间的串扰。尽管单体具有相同的氨基酸序列，但构成PGHS同型二聚体的两个单体的构象不同。一种单体结合 FA 并充当变构单体，而另一种则充当催化单体。最后也是重要的是，纯化的人 PGHS 对 COX 抑制剂的反应受到 FA 的调节，同样取决于 FA、抑制剂和 PGHS 亚型。对于不同的 COX 抑制剂，FA 可以影响抑制剂与一个或两个单体的结合。 拟议研究的目标是确定 PGHS 及其对广泛使用的 COX 抑制剂的反应如何在分子、细胞和整个动物水平上受到 FA 的影响。我们的基本假设是，体内 PG 的产生和对 COX 抑制剂的反应均受到酶所处的 FA 环境（FA 基调）的显着调节，并且这种 FA 环境很大程度上受到饮食中 FA 组成的影响。我们假设每个人都会根据其遗传背景的饮食习惯建立 FA 基调。我们推测某些 FA 音调会使易感个体容易遭受 COX 抑制剂的不良后果。我们预计，我们描述 FA/COX 抑制剂相互作用的研究将成为改变 COX 抑制剂对不同饮食人群的处方方式以及饮食调整以更安全地使用 COX 抑制剂的第一步。