Convergence of the COX-2 and 5-lipoxygenase pathways

有强有力的证据表明，诱导炎性酶5-脂氧合酶（5-LOX）和 环氧合酶-2（考克斯-2）在动脉粥样硬化、哮喘和许多类型的癌症中起重要作用。两种酶都介导 这些疾病的炎症反应通过白三烯和白藜芦醇的合成， 分别白三烯和前列腺素途径传统上被认为是独立的 生物合成途径，因为朝向任一途径的承诺步骤被认为是生物合成途径的初始氧化。 常见底物花生四烯酸。该建议基于以下发现：5-LOX产物，5S- 羟基二十碳四烯酸（5S-HETE）是一种选择性和高效的氧化底物， 考克斯-2（但不是通过考克斯-1同工酶）。这种考克斯-2的新底物的发现与COX-2的表达密切相关。 两个类花生酸途径。常见的5-LOX/考克斯-2产物是一种新的双内过氧化物，其结构为 类似于前列腺素H2，但与前列腺素H2明显不同。在第一个具体目标中，我们建议分析 花生四烯酸转化为新的双内过氧化物的酶学， 反应动力学、底物特异性和考克斯-2活性肽中5-HETE结合的结构基础 绝佳的价钱将使用RAW 264.7细胞研究双内过氧化物产物的酶促转化， 鼠腹腔巨噬细胞，表达5-LOX和考克斯-2的原型细胞。内源 新的类二十烷酸及其代谢物家族的形成将在小鼠动脉粥样硬化中评估 组织.我们将检验新的二内过氧化物（或其代谢物）具有抗- 炎症特性。初步研究表明，双内过氧化物减弱了 来自刺激的肥大细胞和微血管内皮细胞的白细胞介素-8。涉及的信号传送途径 将使用表达5-LOX和考克斯-2的HMC-1人肥大细胞来研究这种相互作用。 新的5-LOX/考克斯-2交叉途径的表征无疑将导致一个全新的 了解5-LOX和考克斯-2的生物学，它也将揭示新的病因， 调节动脉粥样硬化、哮喘和癌症等疾病的炎症成分。这些 这些研究最终可能导致新的治疗方案，用于治疗这些疾病， 已建立的抗炎药物。

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.