2-Hydroxy-ceramide synthesis by ceramide synthase family: enzymatic basis for the preference of FA chain length.
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.
Mizutani
Yukiko
Y
Laboratory of Biomembrane and Biofunctional Chemistry, Faculty of Advanced Life Sciences, Hokkaido University, Sapporo, Japan.
Kihara
Akio
A
Chiba
Hiroko
H
Tojo
Hiromasa
H
Igarashi
Yasuyuki
Y
D002454:Cell Differentiation / Q000502:physiology; D002460:Cell Line; D002478:Cells, Cultured; D002518:Ceramides / Q000096:biosynthesis*; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007231:Infant, Newborn; D015603:Keratinocytes / Q000166:cytology / Q000201:enzymology / Q000378:metabolism; D006899:Mixed Function Oxygenases / Q000378:metabolism; D005810:Multigene Family; D010088:Oxidoreductases / Q000737:chemistry* / Q000235:genetics; D051049:Sphingosine N-Acyltransferase / Q000737:chemistry* / Q000235:genetics
D002518:Ceramides; D005227:Fatty Acids; D006899:Mixed Function Oxygenases; D010088:Oxidoreductases; C019081:fatty acid alpha-hydroxylase; C108138:dihydroceramide desaturase; C583317:CERS3 protein, human; D051049:Sphingosine N-Acyltransferase