Predominant expression of lysosomal N-acylethanolamine-hydrolyzing acid amidase in macrophages revealed by immunochemical studies
Predominant expression of lysosomal N-acylethanolamine-hydrolyzing acid amidase in macrophages revealed by immunochemical studies
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DOI：
10.1016/j.bbalip.2007.03.005
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发表时间：
2007-05-01
影响因子：
4.8
通讯作者：
Ueda, Natsuo
中科院分区：
文献类型：
--
作者：
Tsuboi, Kazuhito;Zhao, Li-Ying;Ueda, Natsuo
生物活性的N-酰基乙醇胺，包括花生四烯酸（一种内源性大麻素）、N-棕榈酰乙醇胺（一种抗炎物质）和N-油酰乙醇胺（一种抗炎物质）被酶促水解成脂肪酸和乙醇胺。脂肪酸酰胺水解酶在该反应中起主要作用。此外，我们还克隆了一种名为“N-酰基乙醇胺水解酸性酰胺酶（NAAA）”的同工酶的cDNA [K.坪井，Y. X.太阳，Y。Okamoto，N. Araki，T. Tonai，N.上田，N-酰基乙醇胺水解酸性酰胺酶的分子表征，胆酰甘氨酸水解酶家族的新成员，与酸性神经酰胺酶具有结构和功能相似性，J. Biol. Chem. 280（2005）11082-11092]。以前的生化分析表明，NAAA的表达在巨噬细胞和各种大鼠组织，包括肺和脑。为了阐明NAAA的生理意义，我们首次对NAAA进行了免疫化学研究。我们研制了一种针对大鼠NAAA的特异性抗体，并通过Western blotting发现NAAA是糖基化的，并进行特异性蛋白水解。从大鼠肺分离的肺泡巨噬细胞中，NAAA的免疫细胞化学定位于溶酶体。在整个肺组织中，只有肺泡巨噬细胞的NAAA免疫染色。肺泡巨噬细胞中NAAA的mRNA、蛋白水平和活性均明显高于整个肺组织。脑内巨噬细胞抗NAAA抗体染色呈阳性，而小胶质细胞呈阴性。这些结果有力地表明了巨噬细胞作为NAAA在大鼠组织中表达位点的重要性。(C)2007 Elsevier B. V.保留所有权利。
Bioactive N-acylethanolamines, including anandamide (an endocannabinoid), N-palmitoylethanolamine (an anti-inflammatory substance), and N-oleoylethanolamine (an anorexic substance) are enzymatically hydrolyzed to fatty acids and ethanolamine. Fatty acid amide hydrolase plays a major role in this reaction. In addition, we cloned cDNA of an isozyme termed "N-acylethanolamine-hydrolyzing acid amidase (NAAA)" [K. Tsuboi, Y.-X. Sun, Y. Okamoto, N. Araki, T. Tonai, N. Ueda, Molecular characterization of N-acylethanolamine-hydrolyzing acid amidase, a novel member of the choloylglycine hydrolase family with structural and functional similarity to acid ceramidase, J. Biol. Chem. 280 (2005) 11082-11092]. Previous biochemical analyses suggested the expression of NAAA in macrophage cells and various rat tissues including lung and brain. To clarify the physiological significance of NAAA, here we immunochemically studied NAAA for the first time. We developed an antibody specific for rat NAAA, and by Western blotting revealed that NAAA is glycosylated and subjected to specific proteolysis. In alveolar macrophages isolated from rat lung, NAAA was immunocytochemically localized in lysosomes. In the whole lung tissue, only alveolar macrophages were immunostained for NAAA. Conformably, the mRNA and protein levels and activity of NAAA in alveolar macrophages were much higher than those in the whole lung tissue. In brain, intraventricular macrophages were positively stained with anti-NAAA antibody, while microglia appeared to be negative. These results strongly suggested the importance of macrophages as an expression site of NAAA in rat tissues. (C) 2007 Elsevier B.V. All rights reserved.