Poster Topical Area: Vitamins and Minerals
Location: Hall D
Poster Board Number: 466
Objectives: To investigate the connection between folate and sphingolipid metabolism, we evaluated effects of dietary folic acid (FA) on sphingolipid levels in the livers of wild-type (WT) and ceramide synthase 6 (CerS6) knockout (KO) mice.
Methods: Ten-week-old CerS6 KO mice and WT-littermate controls were fed diets containing 0, 2, or 12 ppm FA for four weeks. Animal weight and body composition (MRI) were assessed at 10 and 14 weeks of age. Sphingolipid species, including ceramides (Cer), sphingomyelins (SM), and hexosylceramides (HexCer), in liver samples were measured by LC-MS/MS. Gene expression was evaluated by qPCR with cDNA generated from 10 ng of total liver RNA.
Results: For both genotypes, the 0 ppm FA diet reduced SM levels of all acyl chain lengths while the 12 ppm FA diet increased total SM levels. CerS6 KO mice, irrespective of diet, showed higher levels of SMs than WT mice, with the exception of C16-SM. Of note, differences in SM levels between male and female mice were observed on all diets. The total ceramide levels were ~ 60% higher in CerS6 KO than in WT mice, and did not change in response to diet in either genotype. However, the 0 ppm FA diet induced acyl chain length-specific ceramide changes in the WT animals. C16-ceramide increased by ~75%; C18- and C24- ceramides were also elevated. HexCer species were affected by genotype and diet in both male and female mice. However, the response to FA was much more pronounced in the females, with CerS6 KO mice showing increased levels of all HexCer species, with the exception of C16-HexCer, on the 0 ppm FA diet. Expression levels of ceramide synthases 2, 4 and 5 (qPCR) were changed significantly depending on FA levels. Our experiments also revealed a significant difference in both the body weight gain and fat mass increase over time between the male WT and KO mice.
Conclusion: Alterations of dietary FA induce a sphingolipid response in mouse livers. Significant changes of C16-ceramide in WT livers, but not in CerS6 KO livers, in response to a folate-deficient or folate-over supplemented diet, underscore the key role of CerS6 in mediation of dietary folate effects.
University of North Carolina at Chapel Hill
Concord, North Carolina