2014 Jun 23. pii: jlr.M051284. [Epub ahead of print]
A Novel Activity of Microsomal Epoxide Hydrolase: Metabolism of the Endocannabinoid 2-Arachidonoylglycerol.
Abstract
Microsomal epoxide hydrolase (EPHX1, EC 3.3.2.9) is a highly abundant α/β hydrolase (ABHD) enzyme which is known for its catalytical epoxide hydrolase activity. A wide range of EPHX1 functions has been demonstrated including xenobiotic metabolism; however, characterization of itsendogenous substrates is limited. In this study, we present evidence that EPHX1 metabolizes the abundant endocannabinoid, 2-arachidonoylglycerol (2-AG) to free arachidonic acid (AA) and glycerol. The EPHX1 metabolism of 2-AG was demonstrated using commercially available EPHX1 microsomes as well as PC-3 cells overexpressing EPHX1. Conversely, EPHX1 siRNA markedly reduced the EPHX1 expression and 2-AG metabolism in HepG2 cells and LNCaP cells. A selective EPHX1 inhibitor, 10-hydroxystearamide (10-HSA), inhibited 2-AG metabolism and hydrolysis of a well-known EPHX1 substrate, cis-stilbene oxide (cSO). Among the inhibitors studied, a serine hydrolase inhibitor, methoxy-arachidonyl fluorophosphate (MAFP) was the most potent inhibitor of 2-AG metabolism by EPHX1 microsomes. These results demonstrate that 2-AG is anendogenous substrate for EPHX1, a potential role of EPHX1 in the endocannabinoid signaling and a new AA biosynthetic pathway.
Copyright © 2014, The American Society for Biochemistry and Molecular Biology.
Copyright © 2014, The American Society for Biochemistry and Molecular Biology.
KEYWORDS:
Arachidonic acid; Cytochrome P450; Endocannabinoids; Fatty acid; Mass spectrometry
- PMID:
24958911
[PubMed – as supplied by publisher]
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