title: Identification of the human sphingolipid C4-hydroxylase, hDES2, and its up-regulation during keratinocyte differentiation.
abstract: The C4-hydroxylation of dihydrosphingosine or dihydroceramide is a key reaction in the biosynthesis of phytosphingolipids, both in yeasts and in mammalian cells. Mouse DES2 (mDES2) was recently cloned and shown to work as a Delta4-desaturase/C4-hydroxylase, when expressed in yeast cells. Here, we cloned a human homologue of mDES2, hDES2, by homology search utilizing a BLAST program. When expressed in HEK 293 cells, hDES2 exhibited hydroxylase activity for dihydroceramide. Northern blot analyses of hDES2 revealed high expression in skin, intestines, and kidney, sites reportedly possessing high levels of phytosphingolipids. Furthermore, up-regulation of hDES2 mRNA expression and subsequent phytoceramide production were observed during vitamin C/serum-induced differentiation of human keratinocytes. These results suggest that the newly cloned hDES2 plays an essential role in phytosphingolipid synthesis in human skin and other phytosphingolipid-containing tissues.
authors.affiliation: Department of Biomembrane and Biofunctional Chemistry, Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita 12-jo, Nishi 6-choume, Kita-ku, Sapporo 060-0812, Japan.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Mizutani
authors.forename: Akio
authors.initials: A
authors.lastname: Kihara
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Igarashi
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D002454:Cell Differentiation; D002460:Cell Line; D003001:Cloning, Molecular; D044943:Fatty Acid Desaturases / Q000737:chemistry* / Q000235:genetics; D006639:Histidine / Q000737:chemistry; D006801:Humans; D007231:Infant, Newborn; D015603:Keratinocytes / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D006899:Mixed Function Oxygenases / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012867:Skin / Q000166:cytology; D014018:Tissue Distribution; D015854:Up-Regulation
chemical_list: D012333:RNA, Messenger; D006639:Histidine; D006899:Mixed Function Oxygenases; D044943:Fatty Acid Desaturases