Involvement of the γ Isoform of cPLA2 in the Biosynthesis of Bioactive N-Acylethanolamines

Abstract

Arachidonylethanolamide (anandamide) acts as an endogenous ligand of cannabinoid receptors, while other N-acylethanolamines (NAEs), such as palmitylethanolamide and oleylethanolamide, show analgesic, anti-inflammatory, and appetite-suppressing effects through other receptors. In mammalian tissues, NAEs, including anandamide, are produced from glycerophospholipid via N-acyl-phosphatidylethanolamine (NAPE). The ɛ isoform of cytosolic phospholipase A2 (cPLA2) functions as an N-acyltransferase to form NAPE. Since the cPLA2 family consists of six isoforms (α, β, γ, δ, ɛ, and ζ), the present study investigated a possible involvement of isoforms other than ɛ in the NAE biosynthesis. Firstly, when the cells overexpressing one of the cPLA2 isoforms were labeled with [14C]ethanolamine, the increase in the production of [14C]NAPE was observed only with the ɛ-expressing cells. Secondly, when the cells co-expressing ɛ and one of the other isoforms were analyzed, the increase in [14C]N-acyl-lysophosphatidylethanolamine (lysoNAPE) and [14C]NAE was seen with the combination of ɛ and γ isoforms. Furthermore, the purified cPLA2γ hydrolyzed not only NAPE to lysoNAPE, but also lysoNAPE to glycerophospho-N-acylethanolamine (GP-NAE). Thus, the produced GP-NAE was further hydrolyzed to NAE by glycerophosphodiesterase 1. These results suggested that cPLA2γ is involved in the biosynthesis of NAE by its phospholipase A1/A2 and lysophospholipase activities.

Group IVE cytosolic phospholipase A 2 limits psoriatic inflammation by mobilizing the anti‐inflammatory lipid N ‐acylethanolamine

“…cPLA 2 γ, which does not possess a C2 domain characteristic of the cPLA 2 family, has been implicated in phospholipid remodeling through Ca 2+ ‐independent PLA 2 , lysophospholipase and transacylase activities 77–79 . Interestingly, it has recently been reported that cPLA 2 γ also has the ability to hydrolyze NAPEs through sequential PLA 2 and lysophospholipase activities to produce GP‐NAE in vitro 59 . However, considering the low expression of cPLA 2 γ in mouse skin, it is unclear whether cPLA 2 γ could act downstream of cPLA 2 ε to regulate NAE biosynthesis in the skin.…”

“…[77][78][79] Interestingly, it has recently been reported that cPLA 2 γ also has the ability to hydrolyze NAPEs through sequential PLA 2 and lysophospholipase activities to produce GP-NAE in vitro. 59 However, considering the low expression of cPLA 2 γ in mouse skin, it is unclear whether cPLA 2 γ could act downstream of cPLA 2 ε to regulate NAE biosynthesis in the skin.…”

“…On the basis of their catalytic activities, several enzymes have been implicated in the NAPE/NAE-metabolic pathway (Figure S2B). cPLA 2 ε 42,43 and phospholipase A/acyltransferase-1 (PLAAT-1) 56 act as Ca 2+ -dependent and -independent N-acyltransferases, respectively; NAPE-PLD acts as an NAPE-specific PLD 57 ; α/βhydrolase domain containing 4 (ABHD4) 58 and group IVC cPLA 2 (cPLA 2 γ/PLA2G4C) 59 act as NAPE-hydrolyzing PLA 2 s/ lysophospholipases; and GDE1 and GDE4 act as GP-NAEdegrading glycerophosphodiesterases. 60 To clarify which of these enzymes might be involved in the synthesis of these NAE-related lipids during the course of psoriasis, we monitored the kinetic expression of these enzymes in IMQ-treated skin by qPCR.…”

Deciphering Complex Interactions in Bioactive Lipid Signaling

“…AEA is produced mainly via N -acylphosphatidylethanolamines-specific phospholipase D (NAPE-PLD) [ 28 ], and 2-AG mainly via sn -1-diacylglycerol lipases (DAGLs) α and β [ 29 ]. Yet, additional biosynthetic enzymes can contribute to AEA and 2-AG production, such as cytosolic phospholipase A 2γ [ 30 ], phospholipase C [ 31 ] and the αβ-hydrolase domain 4 (ABHD4) protein [ 32 ]. Then, degradation of AEA is primarily catalyzed by fatty acid amide hydrolase (FAAH), which cleaves it into AA and ethanolamine [ 33 ].…”

Tribute to Professor Raphael Mechoulam, The Founder of Cannabinoid and Endocannabinoid Research

“…Since the cPLA 2 family consists of six isoforms (α, β, γ, δ, ɛ, and ζ), the present study investigates a possible involvement of the isoforms other than ɛ in NAE biosynthesis. Presented results suggest that indeed cPLA2γ is involved in the biosynthesis of NAEs through its phospholipase A 1 /A 2 and lysophospholipase activities [ 19 ].…”