Glycine N-acyltransferase-like 3 is responsible for long-chain N-acylglycine formation in N18TG2 cells

Long-chain fatty acid amides are signaling lipids found in mammals and other organisms; however, details of the metabolic pathways for the N-acylglycines and primary fatty acid amides (PFAMs) have remained elusive. Heavylabeled precursor and subtraction lipidomic experiments in mouse neuroblastoma N₁₈TG₂ cells, a model cell line for the study of fatty acid amide metabolism, establish the biosynthetic pathways for the N-acylglycines and the PFAMs. We provide evidence that the N-acylglycines are formed by a long-chain specific glycine-conjugating enzyme, glycine N-acyltransferase-like 3 (GLYATL3). siRNA knockdown of GLYATL3 in the N₁₈TG₂ cells resulted in a decrease in the levels of the N-acylglycines and the PFAMs. This is the first report of an enzyme responsible for long-chain N-acylglycine production in cellula. The production of the PFAMs in N18TG2 cells was reported to occur by the oxidative cleavage of the N-acylglycines, as catalyzed by peptidylglycine α- Amidating monooxygenase (PAM). siRNA knockdown of PAM resulted in an accumulation of [¹³C₁₈]N-oleoylglycine and decreased levels of [13C18]oleamide when the N₁₈TG₂ cells were grown in the presence of [¹³C₁₈]oleic acid. The addition of [1-¹³C]palmitate to the N₁₈TG₂ cell growth media led to the production of a family of [1-¹³C]palmitoylated fatty acid amides, consistent with the biosynthetic pathways detailed herein.-Jeffries, K. A., D. R. Dempsey, E. K. Farrell, R. L. Anderson, G. J. Garbade, T. S. Gurina, I. Gruhonjic, C. A. Gunderson, and D. J. Merkler. Glycine N-acyltransferase-like 3 is responsible for longchain N-acylglycine formation in N18TG2 cells. J. Lipid Res. 2016. 57: 781-790.