Li Rongsong, Mouillesseaux Kevin P, Montoya Dennis, Cruz Daniel, Gharavi Navid, Dun Martin, Koroniak Lukasz, Berliner Judith A
Department of Pathology, University of California, Los Angeles, CA 90095, USA.
Circ Res. 2006 Mar 17;98(5):642-50. doi: 10.1161/01.RES.0000207394.39249.fc. Epub 2006 Feb 2.
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 beta1 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 beta1 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.
氧化型1-棕榈酰-2-花生四烯酰-sn-甘油-3-磷酸胆碱（OxPAPC）已被证明会在动脉粥样硬化病变和其他慢性炎症部位蓄积，它通过激活内皮β1整合素以及随后在顶端表面沉积纤连蛋白，来激活内皮细胞（EC）以结合单核细胞。我们之前的研究表明，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-2-环氧异前列腺素E2-sn-甘油-3-磷酸胆碱）是OxPAPC中激活该途径的最具活性的脂质。我们使用报告基因测定法筛选了许多候选GPCR与OxPAPC和PEIPC的相互作用；我们鉴定出前列腺素E2受体EP2和前列腺素D2受体DP对OxPAPC有反应。我们重点研究了在内皮细胞、单核细胞和巨噬细胞中表达的EP2。OxPAPC成分PEIPC而非POVPC激活了EP2，其半数有效浓度（EC50）为108.6 nmol/L。在配体结合试验中，OxPAPC和PEIPC也能够与前列腺素E2竞争结合EP2。EP2特异性激动剂布他前列素被证明可模拟OxPAPC对β1整合素激活以及单核细胞与内皮细胞结合刺激的作用。布他前列素还模拟了OxPAPC对单核细胞衍生细胞中肿瘤坏死因子-α和白细胞介素-10调节的作用。EP2拮抗剂AH6809在HEK293细胞中阻断了OxPAPC对EP2的激活，并在单核细胞THP-1细胞中阻断了对PEIPC的白细胞介素-10反应。这些结果表明，在内皮细胞和巨噬细胞中，EP2作为OxPAPC和PEIPC的受体发挥作用，无论是作为磷脂酯还是释放的脂肪酸。
