GM3 Ganglioside Linked to Neurofibrillary Pathology in a Transgenic Rat Model for Tauopathy.

Glycosphingolipids (GSLs) are amphipathic lipids composed of a sphingoid base and a fatty acyl attached to a saccharide moiety. GSLs play an important role in signal transduction, directing proteins within the membrane, cell recognition, and modulation of cell adhesion. Gangliosides and sulfatides belong to a group of acidic GSLs, and numerous studies report their involvement in neurodevelopment, aging, and neurodegeneration. In this study, we used an approach based on hydrophilic interaction liquid chromatography (HILIC) coupled to high-resolution tandem mass spectrometry (HRMS/MS) to characterize the glycosphingolipid profile in rat brain tissue. Then, we screened characterized lipids aiming to identify changes in glycosphingolipid profiles in the normal aging process and tau pathology. Thorough screening of acidic glycosphingolipids in rat brain tissue revealed 117 ganglioside and 36 sulfatide species. Moreover, we found two ganglioside subclasses that were not previously characterized-GT1b-Ac2 and GQ1b-Ac2. The semi-targeted screening revealed significant changes in the levels of sulfatides and GM1a gangliosides during the aging process. In the transgenic SHR24 rat model for tauopathies, we found elevated levels of GM3 gangliosides which may indicate a higher rate of apoptotic processes.

Characterization of a Novel Rhamnose-containing Acidic Glycosphingolipid from the Ascidian Halocynthia aurantium.

Halocynthia aurantium, an edible ascidian species belonging to Urochordata, was subjected to structural characterization of acidic glycosphingolipids to investigate these molecules in ascidians: sulfatide from Ciona intestinalis and the glucuronic acid-containing acidic glycosphingolipid from H. roretzi. Acidic glycosphingolipids containing three or five sugars were isolated from soft parts of the ascidian H. aurantium by chloroform-methanol extraction, mild-alkaline hydrolysis, precipitation with cold acetone, and subsequent column chromatography using a DEAE-Sephadex A-25 column, a Florisil column, and an Iatrobead column. The structures of these glycosphingolipids were determined by methylation studies, sugar analysis, fatty acid analysis, sphingoid analysis, mass spectrometry, and proton nuclear magnetic resonance spectroscopy. A novel glucuronic acid-containing glycosphingolipid having a rhamnose residue was identified as Rhaα1-3GlcNAcß1-3Galß1-4(Fucα1-3)GlcAß1-Cer (UGL-2). This novel structure is particularly unusual given that it contains both a rhamnose residue and a reducing terminal glucuronic acid residue within a single molecule. Rhamnose is a characteristic sugar, which is a component of cell wall pectin in plants and exopolysaccharides in bacteria. Ascidians acquired the cellulose synthase gene via lateral gene transfer, and therefore, it can be speculated that they also acquired the rhamnosyltransferase gene in the same manner. We also detected Galß1-4(Fucα1-3)GlcAß1-Cer (UGL-1), which was already identified in another ascidian, H. roretzi.

Invariant Valpha14 natural killer T cell activation by edible mushroom acidic glycosphingolipids.

Invariant natural killer T (iNKT) cells regulate multi-immune response through Th1/Th2 cytokine release triggered by the recognition of CD1d-restricted glycosphingolipid antigens. Here we report that acidic glycosphingolipids (AGLs) of mushroom (Hypsizigus marmoreus and Pleurotus eryngii) presented by murine CD1d-transfected rat basophilic leukocytes induced interleukin-2 (IL-2) release from iNKT hybridoma cells. AGL-1, one of the AGLs, containing mannose at the non-reducing ends, induced CD1d-dependent IL-2 release. Al-though alpha-galactosylceramide (alpha-GalCer) presented by CD11c-positive cells induced both interferon-gamma (IFN-gamma) and IL-4 release, all of AGLs presented by CD11c-positive cells and AGL-1 presented by B cells induced IL-4 release from iNKT hybridoma cells. A single intravenous injection of AGLs into B6 mice induced only a little elevation of IL-4 in serum but repeated intravenous injection of AGLs induced prolonged retention of IL-4 in serum; therefore, these results suggested that edible mushroom AGLs might contribute to the retention of immunohomeostasis through the minimum induction of iNKT cell activation in vivo.

Novel fucogangliosides found in human colon adenocarcinoma tissues by means of glycomic analysis.

The structures of acidic glycosphingolipids in colon adenocarcinoma have been analyzed extensively using a number of conventional methods, such as thin-layer chromatography and methylation analysis, and a variety of acidic glycosphingolipids present in the tissues have been reported. However, because of a number of limitations in the techniques used in previous studies in terms of resolution, quantification, and sensitivity, we employed a different method that could be applied to small amounts of tissue. In this technique, the carbohydrate moieties of acidic glycosphingolipids from approximately 20mg of colon adenocarcinoma were released by endoglycoceramidase II and were labeled by pyridylamination. They were separated and structurally characterized by a two-dimensional HPLC mapping technique, electrospray ionization tandem mass spectrometry (ESI-MS/MS), and enzymatic cleavage. A total of 22 major acidic glycosphingolipid structures were identified, and their relative quantities were revealed in detail. They are composed of 1 sulfated (SM3), 1 lacto-series (SLe(a)), 6 kinds of ganglio-series, and 14 kinds of neolacto-series glycosphingolipids. They include most of the acidic glycosphingolipids previously reported to be present in the tissues and two previously unknown fucogangliosides sharing the same terminal structure: NeuAcalpha2-6(Fucalpha1-2)Galbeta1-4GlcNAcbeta1-3Galbeta1-4Glc, and NeuAcalpha2-6(Fucalpha1-2)Galbeta1-4GlcNAcbeta1-3Galbeta1-4(Fucalpha1-3)GlcNAcbeta1-3-Galbeta1-4Glc. Thus, this highly sensitive, high-resolution analysis enabled the identification of novel structures of acidic glycosphingolipids from small amounts of already comprehensively studied cancerous tissues. This method is a powerful tool for microanalysis of glycosphingolipid structures from small quantities of cancerous tissues and should be applicable to different types of malignant tissues.

Isolation and characterization of acidic glycosphingolipids from the gill of the Pacific Salmon (Oncorhynchus keta): a novel hybrid-type ganglioside with isoglobo- and neolacto-Series.

Monosialosyl gangliosides and sulfoglycolipids in the gill of pacific salmon, Oncorhynchus keta, have been prepared by solvent extraction and DEAE-Sephadex column chromatography. Acidic glycolipid bands (M1-M13) detected by thin layer chromatography were separated by Iatrobeads column chromatography and 13 components were characterized by TLC, compositional analysis, methylation analysis, chemical and enzymatic degradation, liquid secondary ion mass spectrometry and (1)H nuclear magnetic resonance spectroscopy. In addition to the acidic glycolipids with known structures (SM4s, SM3, GM3, LM1, GM1b and V(3)alphaFuc,IV(3)betaGalNAc-GM1a), two fractions (M11 and M13) of unknown monosialosyl gangliosides with TLC mobility slower than GM1a were isolated and characterized as having the following structure with a hybrid of isoglobo- and neolacto-series. [formula: see text] Analysis of fatty acid indicated predominance of C24:1 fatty acid in the upper band (M11) and shorter chain saturated fatty acids in the lower band (M13). The tissue concentrations of M11 and M13 were 1.15 and 0.96 mumol/kg wet weight, respectively.