Selective oxygenation of the endocannabinoid 2-arachidonylglycerol by leukocyte-type 12-lipoxygenase.
The endogenous cannabinoid system appears to serve vascular, neurological, immunological, and reproductive functions. The identification of 2-arachidonylglycerol (2-AG) as an endogenous ligand for the central (CB1) and peripheral (CB2) cannabinoid receptors has prompted interest in enzymes capable of modifying or inactivating this endocannabinoid. Porcine leukocyte 12-liopoxygenase (12-LOX) oxygenated 2-AG to the 2-glyceryl ester of 12(S)-hydroperoxyeicosa-5,8,10,14-tetraenoic acid (12-HPETE-G). The k(cat)/K(M) for oxygenation of 2-AG was 40% of the value for arachidonic acid. In contrast to the results with leukocyte 12-LOX, 2-AG oxygenation was not detected with platelet-type 12-LOX. Among a series of structurally related arachidonyl esters, 2-AG served as the preferential substrate for leukocyte 12-LOX. 12(S)-Hydroxyeicosa-5,8,10,14-tetraenoic acid glyceryl ester (12-HETE-G) was produced following addition of 2-AG to COS-7 cells transiently transfected with leukocyte 12-LOX. These results demonstrate that leukocyte-type 12-LOX efficiently oxidizes 2-AG in vitro and in intact cells, suggesting a role for this oxygenase in the endogenous cannabinoid system.
Moody
J S
JS
Department of Biochemistry, Vanderbilt-Ingram Cancer Center and Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
Kozak
K R
KR
Ji
C
C
Marnett
L J
LJ
D000818:Animals; D001092:Arachidonate 12-Lipoxygenase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001095:Arachidonic Acids; D001792:Blood Platelets / Q000201:enzymology; D019556:COS Cells; D063385:Cannabinoid Receptor Modulators; D002186:Cannabinoids / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002853:Chromatography, Liquid; D063388:Endocannabinoids; D005989:Glycerides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D007962:Leukocytes / Q000201:enzymology*; D015227:Lipid Peroxidation; D013058:Mass Spectrometry; D013056:Spectrophotometry, Ultraviolet; D013552:Swine; D014162:Transfection
D001095:Arachidonic Acids; D063385:Cannabinoid Receptor Modulators; D002186:Cannabinoids; D063388:Endocannabinoids; D005989:Glycerides; C094503:glyceryl 2-arachidonate; D001092:Arachidonate 12-Lipoxygenase