Characterization of N-Acyl Phosphatidylethanolamine-Specific Phospholipase-D Isoforms in the Nematode Caenorhabditis elegans

N -acylethanolamines are an important class of lipid signaling molecules found in many species, including the nematode Caenorhabditis elegans ( C. elegans ) where they are involved in development and adult lifespan. In mammals, the relative activity of the biosynthetic enzyme N -acyl phosphatidylethanolamine-specific phospholipase-D and the hydrolytic enzyme fatty acid amide hydrolase determine N -acylethanolamine levels. C. elegans has two N -acyl phosphatidylethanolamine-specific phospholipase-D orthologs, nape-1 and nape-2 , that are likely to have arisen from a gene duplication event. Here, we find that recombinant C. elegans NAPE-1 and NAPE-2 are capable of generating N -acylethanolamines in vitro , confirming their functional conservation. In vivo , they exhibit overlapping expression in the pharynx and the nervous system, but are also expressed discretely in these and other tissues, suggesting divergent roles. Indeed, nape-1 over-expression results in delayed growth and shortened lifespan only at 25°C, while nape-2 over-expression results in significant larval arrest and increased adult lifespan at 15°C. Interestingly, deletion of the N -acylethanolamine degradation enzyme faah-1 exacerbates nape-1 over-expression phenotypes, but suppresses the larval arrest phenotype of nape-2 over-expression, suggesting that faah-1 is coupled to nape-2 , but not nape-1 , in a negative feedback loop. We also find that over-expression of either nape-1 or nape-2 significantly enhances recovery from the dauer larval stage in the insulin signaling mutant daf-2(e1368) , but only nape-1 over-expression reduces daf-2 adult lifespan, consistent with increased levels of the N -acylethanolamine eicosapentaenoyl ethanolamine. These results provide evidence that N -acylethanolamine biosynthetic enzymes in C. elegans have conserved function and suggest a temperature-dependent, functional divergence between the two isoforms.