Lipidomic Analysis Reveals Altered Fatty Acid Metabolism in the Liver of the Symptomatic Niemann-Pick, Type C1 Mouse Model.

Niemann-Pick disease, type C1 (NPC1) is a fatal, autosomal recessive, neurodegenerative disorder caused by mutations in the NPC1 gene. As a result of the genetic defect, there is accumulation of unesterified cholesterol and sphingolipids in the late endosomal/lysosomal system causing both visceral and neurological defects. These manifest clinically as hepatosplenomegaly, liver dysfunction, and neurodegeneration. While significant progress has been made to better understand NPC1, the downstream effects of cholesterol storage and the major mechanisms that drive these pathologies remains less understood. In this study, it is sought to investigate free fatty acid levels in Npc1^-/- mice with focus on the polyunsaturated ω-3 and ω-6 fatty acids. Since fatty acids are the main constituents of numerous lipids species, a discovery based lipidomic study of liver tissue in Npc1^-/- mice is also performed. To this end, alterations in fatty acid synthesis, including the ω-3 and 6 fatty acids, are reported. Further, alterations in enzymes that regulate the synthesis of ω-3 and 6 fatty acids are reported. Analysis of the liver lipidome reveals alterations in both storage and membrane lipids including ceramides, fatty acids, phosphatidylcholamines, phosphatidylglycerols, phosphatidylethanolamines, sphingomyelins, and triacylglycerols in Npc1^-/- mice at a late stage of disease.