3-O-acetyl-sphingosine-series myelin glycolipids

Abstract

Several glycosphingolipids, less polar than galactosylceramide (GalCer), have been purified from rat brain and designated as fast migrating cerebrosides (FMCs). They co-appear with GalCer during myelinogenesis, reach a peak concentration at postnatal day 25–30 and are derivatives of GalCer. Extensive structural analysis of the partially methylated alditol acetates, mass-spectrometry, and 1H- and 13C-nuclear magnetic resonance (NMR) spectroscopy unequivocally established the structure of two of these FMCs as 3-O-acetyl-sphingosine GalCer with non-hydroxy and hydroxy fatty N-acylation respectively. That is, an acetyl group is linked at the C3-OH of the sphingosine base of GalCer. In addition, NMR spectroscopy of all of the purified FMCs indicates that they contain a 3-O-acetyl group linked with sphingosine and thus delineates a novel series. Several lines of evidence indicate that FMCs are myelin constituents. FMCs, enriched in both central nervous system (CNS) and peripheral nervous system (PNS) myelin, are concentrated in spinal cord and white matter that are composed of myelinated nerve fibers. There is N-acylation with α-hydroxy and C18 and C24 fatty acids, all characteristic of myelin components. They disappear along with GalCer in the murine genetic dysmyelinating disorders, jimpy and quaking, and in a knockout mutant which is devoid of GalCer. In addition, a decrease in FMC and GalCer concentration has been found in Krabbé's disease, a human genetic dysmyelinating disorder.—Dasgupta, S., S. B. Levery, and E. L. Hogan. 3-O-acetyl-sphingosine-series myelin glycolipids: characterization of novel 3-O-acetyl-sphingosine galactosylceramide. J. Lipid Res. 2002. 43: 751–761.

Keywords

• dysmyelinating disorder
• mass spectrometry
• monoglycosylceramide
• nuclear magnetic resonance spectroscopy
• vertebrate brain