Identification of prostaglandin E2 receptor subtype 2 as a receptor activated by OxPAPC
Identification of prostaglandin E2 receptor subtype 2 as a receptor activated by OxPAPC
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DOI：
10.1161/01.res.0000207394.39249.fc
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发表时间：
2006-03-17
影响因子：
20.1
通讯作者：
Berliner, JA
中科院分区：
文献类型：
--
作者：
Li, RS;Mouillesseaux, KP;Berliner, JA
氧化型1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine可聚集在动脉粥样硬化病变和其他慢性炎症部位，通过激活内皮细胞β1整合素和纤维粘连蛋白沉积在根尖表面，激活内皮细胞与单核细胞结合。我们以前的研究表明OxPAPC的这一功能是通过Gs蛋白偶联受体(GPCR)介导的。PEIPC(1-棕榈酰基-2-环氧基异前列腺素E2-sn-甘油-3-磷酰胆碱)是OxPAPC中激活这一途径的最活跃的脂类。我们利用报告基因实验筛选了一些与OxPAPC和PEIPC相互作用的候选GPCRs；我们鉴定了前列腺素E_2受体EP2和前列腺素D2受体DP对OxPAPC有反应。我们重点研究了EP2，它在内皮细胞、单核细胞和巨噬细胞中表达。在配体结合实验中，OxPAPC组分PEIPC激活EP2的EC50值为108.6 nmol/L，而POVPC不能激活EP2。EP2特异性激动剂Butaprost可模拟OxPAPC对β1整合素的激活和单核细胞与内皮细胞结合的刺激作用。Butaprost还模拟了OxPAPC对单核细胞中肿瘤坏死因子-α和白介素10的调节作用。EP2拮抗剂AH6809在HEK293细胞中阻断OxPAPC对EP2的激活，在单核细胞THP-1细胞中阻断IL-10对PEIPC的反应。这些结果表明，EP2在内皮细胞和巨噬细胞中都是OxPAPC和PEIPC的受体，既可以是磷脂酯，也可以是释放的脂肪酸。
Oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine (OxPAPC), which has been shown to accumulate in atherosclerotic lesions and other sites of chronic inflammation, activates endothelial cells (EC) to bind monocytes by activation of endothelial beta 1 integrin and subsequent deposition of fibronectin on the apical surface. Our previous studies suggest this function of OxPAPC is mediated via a Gs protein-coupled receptor (GPCR). PEIPC (1-palmitoyl-2-epoxyisoprostane E2-sn-glycero-3-phosphorylcholine) is the most active lipid in OxPAPC that activates this pathway. We screened a number of candidate GPCRs for their interaction with OxPAPC and PEIPC, using a reporter gene assay; we identified prostaglandin E2 receptor EP2 and prostaglandin D2 receptor DP as responsive to OxPAPC. We focused on EP2, which is expressed in ECs, monocytes, and macrophages. OxPAPC component PEIPC, but not POVPC, activated EP2 with an EC50 of 108.6 nmol/ L. OxPAPC and PEIPC were also able to compete with PGE2 for binding to EP2 in a ligand-binding assay. The EP2 specific agonist butaprost was shown to mimic the effect of OxPAPC on the activation of beta 1 integrin and the stimulation of monocyte binding to endothelial cells. Butaprost also mimicked the effect of OxPAPC on the regulation of tumor necrosis factor-alpha and interleukin-10 in monocyte-derived cells. EP2 antagonist AH6809 blocked the activation of EP2 by OxPAPC in HEK293 cells and blocked the interleukin-10 response to PEIPC in monocytic THP-1 cells. These results suggest that EP2 functions as a receptor for OxPAPC and PEIPC, either as the phospholipid ester or the released fatty acid, in both endothelial cells and macrophages.