title: Involvement of phospholipase A/acyltransferase-1 in N-acylphosphatidylethanolamine generation.
abstract: Anandamide and other bioactive N-acylethanolamines (NAEs) are a class of lipid mediators and are produced from glycerophospholipids via N-acylphosphatidylethanolamines (NAPEs). Although the generation of NAPE by N-acylation of phosphatidylethanolamine is thought to be the rate-limiting step of NAE biosynthesis, the enzyme responsible, N-acyltransferase, remains poorly characterized. Recently, we found that five members of the HRAS-like suppressor (HRASLS) family, which were originally discovered as tumor suppressors, possess phospholipid-metabolizing activities including NAPE-forming N-acyltransferase activity, and proposed to call HRASLS1-5 phospholipase A/acyltransferase (PLA/AT)-1-5, respectively. Among the five members, PLA/AT-1 attracts attention because of its relatively high N-acyltransferase activity and predominant expression in testis, skeletal muscle, brain and heart of human, mouse and rat. Here, we examined the formation of NAPE by PLA/AT-1 in living cells. As analyzed by metabolic labeling with [(14)C]ethanolamine or [(14)C]palmitic acid, the transient expression of human, mouse and rat PLA/AT-1s in COS-7 cells as well as the stable expression of human PLA/AT-1 in HEK293 cells significantly increased the generation of NAPE and NAE. Liquid chromatography-tandem mass spectrometry also exhibited that the stable expression of PLA/AT-1 enhanced endogenous levels of NAPE, N-acylplasmenylethanolamine, NAE and glycerophospho-NAE. Furthermore, the knockdown of endogenous PLA/AT-1 in mouse ATDC5 cells lowered NAPE levels. Interestingly, the dysfunction of peroxisomes, which was caused by PLA/AT-2 and -3, was not observed in the PLA/AT-1-expressing HEK293 cells. Altogether, these results suggest that PLA/AT-1 is at least partly responsible for the generation of NAPE in mammalian cells.
authors.affiliation: Department of Biochemistry, Kagawa University School of Medicine, 1750-1 Ikenobe, Miki, Kagawa 761-0793, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Uyama
authors.forename: Manami
authors.initials: M
authors.lastname: Inoue
authors.forename: Yoko
authors.initials: Y
authors.lastname: Okamoto
authors.forename: Naoki
authors.initials: N
authors.lastname: Shinohara
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Tai
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Tsuboi
authors.forename: Tomohito
authors.initials: T
authors.lastname: Inoue
authors.forename: Akira
authors.initials: A
authors.lastname: Tokumura
authors.forename: Natsuo
authors.initials: N
authors.lastname: Ueda
mesh_terms: D000215:Acylation; D000818:Animals; D019556:COS Cells; D002250:Carbon Radioisotopes; D002522:Chlorocebus aethiops; D019856:Ethanolamine / Q000378:metabolism; D004983:Ethanolamines / Q000378:metabolism*; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D019308:Palmitic Acid / Q000378:metabolism; D020675:Peroxisomes / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000096:biosynthesis*; D010741:Phospholipases A / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction
chemical_list: D002250:Carbon Radioisotopes; D004983:Ethanolamines; D007527:Isoenzymes; D026901:Membrane Transport Proteins; C022203:N-acylethanolamines; D010714:Phosphatidylethanolamines; D034741:RNA, Small Interfering; C484549:SLC33A1 protein, human; D019308:Palmitic Acid; D019856:Ethanolamine; D010741:Phospholipases A
keywords: Endocannabinoid; HRASLS family; N-acylethanolamine; N-acylphosphatidylethanolamine; N-acyltransferase; Phospholipid