The fish oil constituent docosahexaenoic acid (DHA, 22:6 n-3) is a signaling lipid with anti-inflammatory properties. The molecular mechanisms underlying the biological effect of DHA are poorly understood. Here, we report the design, synthesis, and application of a complementary pair of bio-orthogonal, photoreactive probes based on the polyunsaturated scaffold DHA and its oxidative metabolite 17-hydroxydocosahexaenoic acid (17-HDHA). In these probes, an alkyne serves as a handle to introduce a fluorescent reporter group or a biotin-affinity tag via copper(I)-catalyzed azide-alkyne cycloaddition. This pair of chemical probes was used to map specific targets of the omega-3 signaling lipids in primary human macrophages. Prostaglandin reductase 1 (PTGR1) was identified as an interaction partner that metabolizes 17-oxo-DHA, an oxidative metabolite of 17-HDHA. 17-oxo-DHA reduced the formation of pro-inflammatory lipids 5-HETE and LTB4 in human macrophages and neutrophils. Our results demonstrate the potential of comparative photoaffinity protein profiling for the discovery of metabolic enzymes of bioactive lipids and highlight the power of chemical proteomics to uncover new biological insights.

中文翻译：

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Omega-3 信号脂质探针的比较光亲和分析表明前列腺素还原酶 1 是人类巨噬细胞中的代谢中枢

鱼油成分二十二碳六烯酸 (DHA，22:6 n-3) 是一种具有抗炎特性的信号脂质。人们对 DHA 生物学效应的分子机制知之甚少。在这里，我们报告了基于多不饱和支架 DHA 及其氧化代谢物 17-羟基二十二碳六烯酸 (17-HDHA) 的一对互补生物正交光反应探针的设计、合成和应用。在这些探针中，炔作为手柄通过铜 (I) 催化的叠氮-炔环加成引入荧光报告基团或生物素亲和标签。这对化学探针用于绘制原代人类巨噬细胞中 omega-3 信号脂质的特定靶标。前列腺素还原酶 1 (PTGR1) 被确定为代谢 17-oxo-DHA 的相互作用伙伴，17-HDHA 的氧化代谢产物。17-oxo-DHA 减少了人类巨噬细胞和中性粒细胞中促炎脂质 5-HETE 和 LTB4 的形成。我们的研究结果证明了比较光亲和蛋白分析在发现生物活性脂质代谢酶方面的潜力，并突出了化学蛋白质组学发现新生物学见解的能力。