Juniperonic Acid Biosynthesis is Essential in Caenorhabditis elegans Lacking Δ6 Desaturase (fat-3) and Generates New ω-3 Endocannabinoids

Abstract

In eukaryotes, the C20:4 polyunsaturated fatty acid arachidonic acid (AA) plays important roles as a phospholipid component, signaling molecule and precursor of the endocannabinoid-prostanoid axis. Accordingly, the absence of AA causes detrimental effects. Here, compensatory mechanisms involved in AA deficiency in Caenorhabditis elegans were investigated. We show that the ω-3 C20:4 polyunsaturated fatty acid juniperonic acid (JuA) is generated in the C. elegans fat-3(wa22) mutant, which lacks Δ6 desaturase activity and cannot generate AA and ω-3 AA. JuA partially rescued the loss of function of AA in growth and development. Additionally, we observed that supplementation of AA and ω-3 AA modulates lifespan of fat-3(wa22) mutants. We described a feasible biosynthetic pathway that leads to the generation of JuA from α-linoleic acid (ALA) via elongases ELO-1/2 and Δ5 desaturase which is rate-limiting. Employing liquid chromatography mass spectrometry (LC-MS/MS), we identified endocannabinoid-like ethanolamine and glycerol derivatives of JuA and ω-3 AA. Like classical endocannabinoids, these lipids exhibited binding interactions with NPR-32, a G protein coupled receptor (GPCR) shown to act as endocannabinoid receptor in C. elegans. Our study suggests that the eicosatetraenoic acids AA, ω-3 AA and JuA share similar biological functions. This biosynthetic plasticity of eicosatetraenoic acids observed in C. elegans uncovers a possible biological role of JuA and associated ω-3 endocannabinoids in Δ6 desaturase deficiencies, highlighting the importance of ALA.