Involvement of the γ Isoform of cPLA<sub>2</sub> in the Biosynthesis of Bioactive <i>N-</i>Acylethanolamines

oleh: Yiman Guo, Toru Uyama, S. M. Khaledur Rahman, Mohammad Mamun Sikder, Zahir Hussain, Kazuhito Tsuboi, Minoru Miyake, Natsuo Ueda

Format: Article
Diterbitkan: MDPI AG 2021-08-01

Deskripsi

Arachidonylethanolamide (anandamide) acts as an endogenous ligand of cannabinoid receptors, while other <i>N-</i>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 <i>N-</i>acyl-phosphatidylethanolamine (NAPE). The ɛ isoform of cytosolic phospholipase A<sub>2</sub> (cPLA<sub>2</sub>) functions as an <i>N-</i>acyltransferase to form NAPE. Since the cPLA<sub>2</sub> 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 cPLA<sub>2</sub> isoforms were labeled with [<sup>14</sup>C]ethanolamine, the increase in the production of [<sup>14</sup>C]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 [<sup>14</sup>C]<i>N</i>-acyl-lysophosphatidylethanolamine (lysoNAPE) and [<sup>14</sup>C]NAE was seen with the combination of ɛ and γ isoforms. Furthermore, the purified cPLA<sub>2</sub>γ hydrolyzed not only NAPE to lysoNAPE, but also lysoNAPE to glycerophospho-<i>N</i>-acylethanolamine (GP-NAE). Thus, the produced GP-NAE was further hydrolyzed to NAE by glycerophosphodiesterase 1. These results suggested that cPLA<sub>2</sub>γ is involved in the biosynthesis of NAE by its phospholipase A<sub>1</sub>/A<sub>2</sub> and lysophospholipase activities.