2-Hydroxy-ceramide synthesis by ceramide synthase family: enzymatic basis for the preference of FA chain length

J Lipid Res. 2008 Nov;49(11):2356-64. doi: 10.1194/jlr.M800158-JLR200. Epub 2008 Jun 9.

Abstract

Ceramide is unusually abundant in epidermal stratum corneum and is important for permeability barrier function. Ceramides in epidermis also comprise an unusual variety, including 2-hydroxy (alpha-hydroxy)-ceramide. Six mammalian ceramide synthase/longevity assurance homologue (CerS/LASS) family members have been identified as synthases responsible for ceramide (CER) production. We reveal here that of the six, CerS3/LASS3 mRNA is the most predominantly expressed in keratinocytes. Moreover, its expression is increased upon differentiation. CerS family members have known substrate specificities for fatty acyl-CoA chain length and saturation, yet their abilities to produce 2-hydroxy-CER have not been examined. In the present study, we demonstrate that all CerS members can produce 2-hydroxy-CER when overproduced in HEK 293T cells. Each produced a 2-hydroxy-CER with a chain length similar to that of the respective nonhydroxy-CER produced. In HeLa cells overproducing the FA 2-hydroxylase FA2H, knock-down of CerS2 resulted in a reduction in total long-chain 2-hydroxy-CERs, confirming enzyme substrate specificity for chain length. In vitro CerS assays confirmed the ability of CerS1 to utilize 2-hydroxy-stearoyl-CoA as a substrate. These results suggest that all CerS members can synthesize 2-hydroxy-CER with specificity for 2-hydroxy-fatty acyl-CoA chain length and that CerS3 may be important in CER and 2-hydroxy-CER synthesis in epidermis.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Differentiation / physiology
  • Cell Line
  • Cells, Cultured
  • Ceramides / biosynthesis*
  • Fatty Acids / chemistry
  • Fatty Acids / metabolism*
  • HeLa Cells
  • Humans
  • Infant, Newborn
  • Keratinocytes / cytology
  • Keratinocytes / enzymology
  • Keratinocytes / metabolism
  • Mixed Function Oxygenases / metabolism
  • Multigene Family*
  • Oxidoreductases / chemistry*
  • Oxidoreductases / genetics
  • Sphingosine N-Acyltransferase / chemistry*
  • Sphingosine N-Acyltransferase / genetics

Substances

  • Ceramides
  • Fatty Acids
  • Mixed Function Oxygenases
  • Oxidoreductases
  • fatty acid alpha-hydroxylase
  • dihydroceramide desaturase
  • CERS3 protein, human
  • Sphingosine N-Acyltransferase