Giménez-Bastida Juan A, Shibata Takahiro, Uchida Koji, Schneider Claus
Department of Pharmacology, Vanderbilt University Medical School, Nashville, Tennessee, USA.
Vanderbilt Institute of Chemical Biology, Vanderbilt University Medical School, Nashville, Tennessee, USA.
FASEB J. 2017 May;31(5):1867-1878. doi: 10.1096/fj.201601136R. Epub 2017 Jan 17.
The 2 hemiketal (HK) eicosanoids HKD and HKE are the major products of the biosynthetic crossover of the 5-lipoxygenase (5-LOX) and cyclooxygenase-2 (COX-2) pathways. HKs result from the rearrangement of a di-endoperoxide intermediate formed in the COX-2-dependent oxygenation of 5-hydroxyeicosatetraenoic acid (5-HETE). We analyzed HK biosynthesis in human leukocytes stimulated and defined the biosynthetic roles of 5-LOX and COX-2, using inhibitors and incubations with exogenous substrates. Activation of leukocytes with LPS followed by treatment with the calcium ionophore A23187 resulted in the formation of PGE, 5-HETE, and LTB as the principal metabolites of COX-2 and 5-LOX, respectively. The formation of HKD and HKE was highest after 15 min LPS treatment, and at that time, levels were similar to PGE, but less than 5-HETE and LTB The time course of HK formation paralleled that of 5-HETE and LTB, implying the availability of the 5-HETE substrate as a limiting factor in biosynthesis rather than expression levels of COX-2. Specific inhibitors of COX-2 and 5-LOX decreased formation of HKD and HKE Platelets did not form HKs from exogenous 5-HETE, implying that COX-1 is not involved. HKs are early products during an inflammatory event and require cells that express 5-LOX and COX-2 for their biosynthesis.-Giménez-Bastida, J. A., Shibata, T., Uchida, K., Schneider, C. Roles of 5-lipoxygenase and cyclooxygenase-2 in the biosynthesis of hemiketals E and D by activated human leukocytes.
半缩酮（HK）类二十烷酸HKD和HKE是5-脂氧合酶（5-LOX）和环氧化酶-2（COX-2）途径生物合成交叉的主要产物。HKs是由5-羟基二十碳四烯酸（5-HETE）在COX-2依赖性氧化过程中形成的双内过氧化物中间体重排产生的。我们使用抑制剂并与外源性底物一起孵育，分析了刺激后的人白细胞中HK的生物合成，并确定了5-LOX和COX-2的生物合成作用。用脂多糖（LPS）激活白细胞，然后用钙离子载体A23187处理，分别导致PGE、5-HETE和LTB的形成，它们分别是COX-2和5-LOX的主要代谢产物。LPS处理15分钟后，HKD和HKE的形成最高，此时其水平与PGE相似，但低于5-HETE和LTB。HK形成的时间进程与5-HETE和LTB的相似，这意味着5-HETE底物的可用性是生物合成中的限制因素，而不是COX-2的表达水平。COX-2和5-LOX的特异性抑制剂降低了HKD和HKE的形成。血小板不能从外源性5-HETE形成HKs，这意味着COX-1不参与其中。HKs是炎症事件中的早期产物，其生物合成需要表达5-LOX和COX-2的细胞。-吉梅内斯-巴斯蒂达，J.A.，柴田，T.，内田，K.，施耐德，C.活化的人白细胞中5-脂氧合酶和环氧化酶-2在半缩酮E和D生物合成中的作用
