Inactivation of N-acyl phosphatidylethanolamine phospholipase D reveals multiple mechanisms for the biosynthesis of endocannabinoids.
N-Acyl ethanolamines (NAEs) constitute a large and diverse class of signaling lipids that includes the endogenous cannabinoid anandamide. Like other lipid transmitters, NAEs are thought to be biosynthesized and degraded on-demand rather than being stored in vesicles prior to signaling. The identification of enzymes involved in NAE metabolism is therefore imperative to achieve a complete understanding of this lipid signaling system and control it for potential therapeutic gain. Recently, an N-acyl phosphatidylethanolamine phospholipase D (NAPE-PLD) was identified as a candidate enzyme involved in the biosynthesis of NAEs. Here, we describe the generation and characterization of mice with a targeted disruption in the NAPE-PLD gene [NAPE-PLD(-/-) mice]. Brain tissue from NAPE-PLD(-/-) mice showed more than a 5-fold reduction in the calcium-dependent conversion of NAPEs to NAEs bearing both saturated and polyunsaturated N-acyl chains. However, only the former group of NAEs was decreased in level in NAPE-PLD(-/-) brains, and these reductions were most dramatic for NAEs bearing very long acyl chains (>or=C20). Further studies identified a calcium-independent PLD activity in brains from NAPE-PLD(-/-) mice that accepted multiple NAPEs as substrates, including the anandamide precursor C20:4 NAPE. The illumination of distinct enzymatic pathways for the biosynthesis of long chain saturated and polyunsaturated NAEs suggests a strategy to control the activity of specific subsets of these lipids without globally affecting the function of the NAE family as a whole.
Leung
Donmienne
D
The Skaggs Institute for Chemical Biology and Department of Cell Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
Saghatelian
Alan
A
Simon
Gabriel M
GM
Cravatt
Benjamin F
BF
D000818:Animals; D001921:Brain / Q000166:cytology / Q000378:metabolism; D063385:Cannabinoid Receptor Modulators / Q000096:biosynthesis*; D063388:Endocannabinoids; D004983:Ethanolamines / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008954:Models, Biological; D008957:Models, Genetic; D010714:Phosphatidylethanolamines / Q000378:metabolism; D010739:Phospholipase D / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
D063385:Cannabinoid Receptor Modulators; D063388:Endocannabinoids; D004983:Ethanolamines; D010714:Phosphatidylethanolamines; D010739:Phospholipase D; D011993:Recombinant Fusion Proteins; C022203:N-acylethanolamines; C506062:Napepld protein, mouse