title: Stereospecificity of fatty acid 2-hydroxylase and differential functions of 2-hydroxy fatty acid enantiomers.
abstract: FA 2-hydroxylase (FA2H) is an NAD(P)H-dependent enzyme that initiates FA α oxidation and is also responsible for the biosynthesis of 2-hydroxy FA (2-OH FA)-containing sphingolipids in mammalian cells. The 2-OH FA is chiral due to the asymmetric carbon bearing the hydroxyl group. Our current study performed stereochemistry investigation and showed that FA2H is stereospecific for the production of (R)-enantiomers. FA2H knockdown in adipocytes increases diffusional mobility of raft-associated lipids, leading to reduced GLUT4 protein level, glucose uptake, and lipogenesis. The effects caused by FA2H knockdown were reversed by treatment with exogenous (R)-2-hydroxy palmitic acid, but not with the (S)-enantiomer. Further analysis of sphingolipids demonstrated that the (R)-enantiomer is enriched in hexosylceramide whereas the (S)-enantiomer is preferentially incorporated into ceramide, suggesting that the observed differential effects are in part due to synthesis of sphingolipids containing different 2-OH FA enantiomers. These results may help clarify the mechanisms underlying the recently identified diseases associated with FA2H mutations in humans and may lead to potential pharmaceutical and dietary treatments. This study also provides critical information to help study functions of 2-OH FA enantiomers in FA α oxidation and possibly other sphingolipid-independent pathways.
authors.affiliation: Department of Internal Medicine, Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: Lin
authors.initials: L
authors.lastname: Guo
authors.forename: Xu
authors.initials: X
authors.lastname: Zhang
authors.forename: Dequan
authors.initials: D
authors.lastname: Zhou
authors.forename: Adewole L
authors.initials: AL
authors.lastname: Okunade
authors.forename: Xiong
authors.initials: X
authors.lastname: Su
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology / Q000201:enzymology / Q000378:metabolism; D000581:Amidohydrolases / Q000378:metabolism*; D000818:Animals; D055162:Biocatalysis; D016466:CHO Cells; D002478:Cells, Cultured; D006224:Cricetinae; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism*; D006880:Hydroxy Acids / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D013107:Sphingolipids / Q000737:chemistry / Q000378:metabolism; D013237:Stereoisomerism; D013379:Substrate Specificity; D000099252:Fatty Acid Amide Hydrolases
chemical_list: D000581:Amidohydrolases; D005227:Fatty Acids; D006880:Hydroxy Acids; D013107:Sphingolipids; D000099252:Fatty Acid Amide Hydrolases