title: Enzymatic formation of N-acylethanolamines from N-acylethanolamine plasmalogen through N-acylphosphatidylethanolamine-hydrolyzing phospholipase D-dependent and -independent pathways.
abstract: Bioactive N-acylethanolamines include anandamide (an endocannabinoid), N-palmitoylethanolamine (an anti-inflammatory), and N-oleoylethanolamine (an anorexic). In the brain, these molecules are formed from N-acylphosphatidylethanolamines (NAPEs) by a specific phospholipase D, called NAPE-PLD, or through NAPE-PLD-independent multi-step pathways, as illustrated in the current study employing NAPE-PLD-deficient mice. Although N-acylethanolamine plasmalogen (1-alkenyl-2-acyl-glycero-3-phospho(N-acyl)ethanolamine, pNAPE) is presumably a major class of N-acylethanolamine phospholipids in the brain, its enzymatic conversion to N-acylethanolamines is poorly understood. In the present study, we focused on the formation of N-acylethanolamines from pNAPEs. While recombinant NAPE-PLD catalyzed direct release of N-palmitoylethanolamine from N-palmitoylethanolamine plasmalogen, the same reaction occurred in the brain homogenate of NAPE-PLD-deficient mice, suggesting that this reaction occurs through both the NAPE-PLD-dependent and -independent pathways. Liquid chromatography-mass spectrometry revealed a remarkable accumulation of 1-alkenyl-2-hydroxy-glycero-3-phospho(N-acyl)ethanolamines (lyso pNAPEs) in the brain of NAPE-PLD-deficient mice. We also found that brain homogenate formed N-palmitoylethanolamine, N-oleoylethanolamine, and anandamide from their corresponding lyso pNAPEs by a Mg(2+)-dependent "lysophospholipase D". Moreover, the brain levels of alkenyl-type lysophosphatidic acids, the other products from lyso pNAPEs by lysophospholipase D, also increased in NAPE-PLD-deficient mice. Glycerophosphodiesterase GDE1 can hydrolyze glycerophospho-N-acylethanolamines to N-acylethanolamines in the brain. In addition, we discovered that recombinant GDE1 has a weak activity to generate N-palmitoylethanolamine from its corresponding lyso pNAPE, suggesting that this enzyme is at least in part responsible for the lysophospholipase D activity. These results strongly suggest that brain tissue N-acylethanolamines, including anandamide, can be formed from N-acylated plasmalogen through an NAPE-PLD-independent pathway as well as by their direct release via NAPE-PLD.
authors.affiliation: Department of Biochemistry, Kagawa University School of Medicine, Kagawa, Japan.
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Tsuboi
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Okamoto
authors.forename: Natsuki
authors.initials: N
authors.lastname: Ikematsu
authors.forename: Manami
authors.initials: M
authors.lastname: Inoue
authors.forename: Yoshibumi
authors.initials: Y
authors.lastname: Shimizu
authors.forename: Toru
authors.initials: T
authors.lastname: Uyama
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.forename: Dale G
authors.initials: DG
authors.lastname: Deutsch
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Burns
authors.forename: Nadine M
authors.initials: NM
authors.lastname: Ulloa
authors.forename: Akira
authors.initials: A
authors.lastname: Tokumura
authors.forename: Natsuo
authors.initials: N
authors.lastname: Ueda
mesh_terms: D000818:Animals; D001095:Arachidonic Acids / Q000378:metabolism; D001921:Brain / Q000378:metabolism; D019556:COS Cells; D002522:Chlorocebus aethiops; D063388:Endocannabinoids; D004983:Ethanolamines / Q000378:metabolism*; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains; D008954:Models, Biological; D009829:Oleic Acids; D010739:Phospholipase D / Q000378:metabolism*; D010955:Plasmalogens / Q000378:metabolism; D053284:Polyunsaturated Alkamides / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D001095:Arachidonic Acids; D063388:Endocannabinoids; D004983:Ethanolamines; D009829:Oleic Acids; D010739:Phospholipase D; D010955:Plasmalogens; D053284:Polyunsaturated Alkamides; C022203:N-acylethanolamines; C033595:N-oleoylethanolamine; C506062:Napepld protein, mouse; C078814:anandamide