Abstract
OBJECTIVES: To characterize metabolomic adjustments in response to alterations of dietary folate in the livers of wild type and Ceramide Synthase 6 (CerS6) deficient mice. METHODS: Ten-week-old CerS6 KO mice and wild-type controls were fed diets containing 0, 2, or 12 ppm of folic acid (FA) for 4 weeks. At the end of the dietary intervention, livers were snap-frozen in liquid nitrogen and tissue samples were subjected to untargeted metabolomics analysis by Metabolon®. RESULTS: Of the 736 measured compounds, 550 biochemicals were significantly different between male and female mice, while 273 metabolites differed by genotype (WT vs CerS6 KO) and 298 by diet (0, 2, or 12 ppm FA). Principal component analysis revealed distinct sex- and genotype-based separations and some diet-based separation. As expected, KO livers exhibited decreased levels of most ceramide-based sphingolipids with C(14)- or C(16)-acyl chains (ceramide, sphingomyelin, glycosyl- and lactosyl- ceramides) and elevated levels of longer acyl-chain sphingolipids. Importantly, genotype-based differences were also observed for other lipid classes, such as phosphatidylethanolamines, free fatty acids, and diacylglycerols, indicating global perturbations of lipid metabolism. Specifically, hepatic phosphatidylethanolamine levels were significantly higher in CerS6 KO mice. These KO mice also gained less weight and accumulated less fat mass over the course of this study, indicating significant changes in whole body metabolism and energetics. Additionally, significant alterations in energy producing pathways (glycolytic and TCA cycle intermediates), as well as acyl-choline and kynurenine pathways were found in CerS6 KO mice. CONCLUSIONS: CerS6 is essential in maintaining the proper balance of several lipid classes and plays an important role in liver homeostasis under conditions of varying dietary folic acid intake. Our data also suggest that re-distribution of major lipid classes may contribute to the prevention of weight gain and fat mass increase in CerS6 KO mice. FUNDING SOURCES: R01 CA193782-01.