Sphinganine 1-phosphate metabolism in cultured skin fibroblasts: evidence for the existence of a sphingosine phosphatase.
On addition of [4,5-3H]sphinganine 1-phosphate to human fibroblast monolayers, the label was efficiently removed from the culture medium. In contrast with the reported stability of phosphorylated sphingenine in 3T3 cells [Desai, Zhang, Olivera, Mattie and Spiegel (1992). J. Biol. Chem. 267, 23122-23128] and B16 melanoma cells [Sadahira, Ruan, Hakomuri and Igarashi (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 9686-9690], sphinganine 1-phosphate appeared to be subjected to a fast and extensive metabolism in fibroblasts, the major pathways being cleavage and dephosphorylation. The first of these pathways, catalysed by sphingosine-phosphate lyase, resulted in the formation of labelled palmitaldehyde, which was recovered, mainly after oxidation, in glycerophospholipids in an ester bond. A smaller part of the palmitaldehyde was reduced and incorporated in alk(en)ylphospholipids. Dephosphorylation of spinganine 1-phosphate, a hitherto overlooked pathway catalysed by an unknown phosphatase(s), gave rise to sphinganine, which was converted by N-acylation into ceramide and then incorporated in spingomyelin and glycosphingolipids.
Van Veldhoven
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PP
Katolieke Universiteit Leuven, Afdeling Farmakologie, Belgium.
Mannaerts
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GP
D000326:Adrenoleukodystrophy / Q000201:enzymology / Q000378:metabolism; D002478:Cells, Cultured; D002648:Child; D005347:Fibroblasts / Q000201:enzymology; D006801:Humans; D006868:Hydrolysis; D010084:Oxidation-Reduction; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D010766:Phosphorylation; D029701:Saccharomyces cerevisiae Proteins; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000378:metabolism; D015211:Zellweger Syndrome / Q000201:enzymology / Q000378:metabolism
D029701:Saccharomyces cerevisiae Proteins; C060504:dihydrosphingosine 1-phosphate; C110252:LCB3 protein, S cerevisiae; C503018:YSR3 protein, S cerevisiae; D010744:Phosphoric Monoester Hydrolases; D013110:Sphingosine; C005682:safingol