Biosynthesis of anandamide and N-palmitoylethanolamine by sequential actions of phospholipase A2 and lysophospholipase D

Biochem J. 2004 Jun 15;380(Pt 3):749-56. doi: 10.1042/BJ20040031.

Abstract

Anandamide (an endocannabinoid) and other bioactive long-chain NAEs (N-acylethanolamines) are formed by direct release from N-acyl-PE (N-acyl-phosphatidylethanolamine) by a PLD (phospholipase D). However, the possible presence of a two-step pathway from N-acyl-PE has also been suggested previously, which comprises (1) the hydrolysis of N-acyl-PE to N-acyl-lysoPE by PLA1/PLA2 enzyme(s) and (2) the release of NAEs from N-acyllysoPE by lysoPLD (lysophospholipase D) enzyme(s). In the present study we report for the first time the characterization of enzymes responsible for this pathway. The PLA1/PLA2 activity for N-palmitoyl-PE was found in various rat tissues, with the highest activity in the stomach. This stomach enzyme was identified as group IB sPLA2 (secretory PLA2), and its product was determined as N-acyl-1-acyl-lysoPE. Recombinant group IB, IIA and V of sPLA2s were also active with N-palmitoyl-PE, whereas group X sPLA2 and cytosolic PLA2a were inactive. In addition, we found wide distribution of lysoPLD activity generating N-palmitoylethanolamine from N-palmitoyl-lysoPE in rat tissues, with higher activities in the brain and testis. Based on several lines of enzymological evidence, the lysoPLD enzyme could be distinct from the known N-acyl-PE-hydrolysing PLD. sPLA2-IB dose dependently enhanced the production of N-palmitoylethanolamine from N-palmitoyl-PE in the brain homogenate showing the lysoPLD activity. N-Arachidonoyl-PE and N-arachidonoyl-lysoPE as anandamide precursors were also good substrates of sPLA2-IB and the lysoPLD respectively. These results suggest that the sequential actions of PLA2 and lysoPLD may constitute another biosynthetic pathway for NAEs, including anandamide.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amides
  • Animals
  • Arachidonic Acids / biosynthesis*
  • Brain / enzymology
  • Cell Line
  • Endocannabinoids
  • Ethanolamines / metabolism
  • Group IB Phospholipases A2
  • Humans
  • Hydrolysis
  • Isoenzymes / metabolism
  • Kidney / cytology
  • Kidney / embryology
  • Male
  • Organ Specificity
  • Palmitic Acids / metabolism*
  • Phosphatidylethanolamines / metabolism
  • Phospholipases A / chemistry
  • Phospholipases A / isolation & purification
  • Phospholipases A / metabolism*
  • Phospholipases A1
  • Phospholipases A2
  • Phosphoric Diester Hydrolases / metabolism*
  • Polyunsaturated Alkamides
  • Rats
  • Rats, Wistar
  • Stomach / enzymology
  • Substrate Specificity

Substances

  • Amides
  • Arachidonic Acids
  • Endocannabinoids
  • Ethanolamines
  • Isoenzymes
  • N-acylethanolamines
  • Palmitic Acids
  • Phosphatidylethanolamines
  • Polyunsaturated Alkamides
  • phosphatidylethanolamine
  • palmidrol
  • Phospholipases A
  • Phospholipases A1
  • Group IB Phospholipases A2
  • PLA2G1B protein, human
  • Phospholipases A2
  • Pla2g1b protein, rat
  • Phosphoric Diester Hydrolases
  • alkylglycerophosphoethanolamine phosphodiesterase
  • anandamide