Profiling of glucosylceramides by liquid chromatography-tandem mass spectrometry

Cell membrane surface glycosphingolipids (GSLs), which are synthesized from glucosylceramide (GlcCer) by the enzymatic action of glucosylceramide synthase (GlcT-1), play fundamental roles in many cellular processes. Recent studies have shown that in adipose tissue, GlcCer is involved in the regulation of energy (fat and sugar) metabolism and that GlcCer acts as a glucose donor in cholesteryl glucoside biosynthesis. To investigate the physiological functions of GlcT-1 and GlcCer, a method to profile GlcCer species by liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) has been recently established. The method is based on a combination analysis of retention times in hydrophilic liquid chromatography (HILIC) with specified head group survey, such as neutral-loss and/or precursor-ion scans. Here, the application of this method for profiling GlcCer species in Drosophila melanogaster fat bodies in which Drosophila GLCT-1 (dGlcT-1) expression was manipulated is described, and the implications of these studies in the context of energy metabolism and obesity are discussed.