Convergence of the COX-2 and 5-lipoxygenase pathways

有强有力的证据表明，炎症酶5-脂氧合酶(5-LOX)和 环氧合酶-2(COX-2)与动脉粥样硬化、哮喘和许多类型的癌症有关。这两种酶都在 这些疾病通过合成白三烯和前列腺素而产生的炎症反应， 分别进行了分析。白三烯和前列腺素通路传统上被认为是独立的。 生物合成途径，因为朝着这两个途径中的任何一个途径的承诺步骤被认为是 常见底物花生四烯酸。这项建议是基于5-LOX产品5S- 羟基二十碳四烯酸(5S-HETE)是一种选择性和高效的底物，通过 COX-2(但不是通过COX-1同工酶)。COX-2这种新型底物的发现将COX-2 两条二十烷酸类通路。常见的5-LOX/COX-2产物是一种新型的双内过氧化产物，其结构是 令人联想到前列腺素H2，但与前列腺素H2截然不同。在第一个具体目标中，我们建议分析 花生四烯酸转化为新型双内过氧物的酶学研究 5-HETE与COX-2活性结合的反应动力学、底物特异性和结构基础 地点。二内过氧化产物的酶转化将使用RAW264.7细胞和 小鼠腹膜巨噬细胞，表达5-LOX和COX-2的典型细胞。内生性 将在小鼠动脉粥样硬化中评估新二十烷类化合物及其代谢物家族的形成 组织。我们将检验这一假设，即新型双内过氧物(或其代谢物)具有抗 炎性物质。初步研究表明，双内过氧物可减弱 刺激的肥大细胞和微血管内皮细胞产生的白介素8。涉及的信号通路 在这种相互作用中，将利用5-LOX和COX-2表达HMC-1人肥大细胞。 对新的5-LOX/COX-2交叉通路的表征无疑将导致一种全新的 了解5-LOX和COX-2的生物学机制，也将有助于对其病因和发病机制的研究。 调节动脉粥样硬化、哮喘和癌症等疾病的炎症成分。这些 研究可能最终导致新的治疗方案，用于治疗这些疾病 久负盛名的抗炎药物。

There is strong evidence for the induction of the inflammatory enzymes 5-lipoxygenase (5-LOX) and cyclooxygenase-2 (COX-2) in atherosclerosis, asthma, and many types of cancer. Both enzymes mediate the inflammatory response of these diseases through the synthesis of leukotrienes and prostaglandins, respectively. The leukotriene and prostaglandin pathways have traditionally been viewed as independent biosynthetic routes since the committed step toward either pathway is taken as the initial oxygenation of the common substrate, arachidonic acid. This proposal is based on the finding that the 5-LOX product, 5S- hydroxyeicosatetraenoic acid (5S-HETE), is a selective and highly efficient substrate for oxygenation by COX-2 (but not by the COX-1 isozyme). The discovery of this novel substrate for COX-2 intimately links the two eicosanoid pathways. The common 5-LOX/COX-2 product is a novel di-endoperoxide that is structurally reminiscent of, but distinctly different from prostaglandin H2. In the first Specific Aim we propose to analyze the enzymology of the conversion of arachidonic acid into the novel di-endoperoxide by establishing the reaction kinetics, substrate specificity, and the structural basis for binding of 5-HETE in the COX-2 active site. The enzymatic transformation of the di-endoperoxide product will be studied using RAW264.7 cells and murine peritoneal macrophages, prototypical cells that expresses both 5-LOX and COX-2. Endogenous formation of the novel eicosanoid and its family of metabolites will be assessed in mouse atherosclerotic tissue. We will test the hypothesis that the novel di-endoperoxide (or its metabolites) possess anti- inflammatory properties. Preliminary studies have shown that the di-endoperoxide attenuates the release of interleukin-8 from stimulated mast cells and microvascular endothelial cells. The signaling pathways involved in this interaction will be studied using the 5-LOX and COX-2 expressing HMC-1 human mast cell. Characterization of the novel 5-LOX/COX-2 cross-over pathway will undoubtedly lead to an entirely new understanding of the biology of 5-LOX and COX-2, and it will also shed new light on the etiology and regulation of the inflammatory component of diseases like atherosclerosis, asthma, and cancer. These studies could ultimately lead to new therapeutic regimens for the treatment of these diseases using established anti-inflammatory medications.