RT Journal Article
SR Electronic
T1 RNA Interference Suggests a Primary Role for Monoacylglycerol Lipase in the Degradation of the Endocannabinoid 2-Arachidonoylglycerol
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 1260
OP 1264
DO 10.1124/mol.104.002071
VO 66
IS 5
A1 Thien P. Dinh
A1 Satish Kathuria
A1 Daniele Piomelli
YR 2004
UL http://molpharm.aspetjournals.org/content/66/5/1260.abstract
AB The endogenous cannabinoid 2-arachidonoylglycerol (2-AG) is produced by neurons and other cells in a stimulus-dependent manner and undergoes rapid biological inactivation through transport into cells and catalytic hydrolysis. The enzymatic pathways responsible for 2-AG degradation are only partially understood. We have shown previously that overexpression of monoacylglycerol lipase (MGL), a cytosolic serine hydrolase that cleaves 1- and 2-monoacylglycerols to fatty acid and glycerol, reduces stimulus-dependent 2-AG accumulation in primary cultures of rat brain neurons. We report here that RNA interference-mediated silencing of MGL expression greatly enhances 2-AG accumulation in HeLa cells. After stimulation with the calcium ionophore ionomycin, 2-AG levels in MGL-silenced cells were comparable with those found in cells in which 2-AG degradation had been blocked using methyl arachidonyl fluorophosphonate, a nonselective inhibitor of 2-AG hydrolysis. The results indicate that MGL plays an important role in the degradation of endogenous 2-AG in intact HeLa cells. Furthermore, immunodepletion experiments show that MGL accounts for at least 50% of the total 2-AG–hydrolyzing activity in soluble fractions of rat brain, suggesting that this enzyme also contributes to 2-AG deactivation in the central nervous system.