title: Predominant expression of lysosomal N-acylethanolamine-hydrolyzing acid amidase in macrophages revealed by immunochemical studies.
abstract: 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.
authors.affiliation: Department of Biochemistry, Kagawa University School of Medicine, 1750-1 Ikenobe, Miki, Kagawa 761-0793, Japan.
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Tsuboi
authors.forename: Li-Ying
authors.initials: LY
authors.lastname: Zhao
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Okamoto
authors.forename: Nobukazu
authors.initials: N
authors.lastname: Araki
authors.forename: Masaki
authors.initials: M
authors.lastname: Ueno
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Sakamoto
authors.forename: Natsuo
authors.initials: N
authors.lastname: Ueda
mesh_terms: D000581:Amidohydrolases / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D017931:DNA Primers; D007150:Immunohistochemistry; D008168:Lung / Q000201:enzymology; D016676:Macrophages, Alveolar / Q000201:enzymology*; D017737:Macrophages, Peritoneal / Q000201:enzymology; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D017931:DNA Primers; D012333:RNA, Messenger; D011994:Recombinant Proteins; D000581:Amidohydrolases; C046993:N-acylethanolamine amidohydrolase