Saki Itonori

Dengue virus type 2 recognizes the carbohydrate moiety of neutral glycosphingolipids in mammalian and mosquito cells

Dengue viruses infect cells by attaching to a surface receptor which remains unknown. The putative receptor molecules of dengue virus type 2 on the surface of mosquito (AP‐61) and mammalian (LLC‐MK2) cell lines were investigated. The immunochemical detection and structural analysis of carbohydrates demonstrated that the neutral glycosphingolipids, L‐3 (GlcNAcβ1‐3Manβ1‐4Glcβ1‐1’Cer) in AP‐61 cells, and nLc4Cer (Galβ1‐4GlcNAcβ1‐3Galβ1‐4Glcβ1‐1’Cer) in LLC‐MK2 cells were recognized by the virus. These findings strongly suggest that neutral glycosphingolipids share the key determinant for virus binding and that the β‐GlcNAc residue may play an important role in dengue virus binding to the host cell surface.

Mushroom acidic glycosphingolipid induction of cytokine secretion from murine T cells and proliferation of NK1.1 α/β TCR-double positive cells in vitro

Interferon (IFN)-gamma and interleukin (IL)-4 regulate many types of immune responses. Here we report that acidic glycosphingolipids (AGLs) of Hypsizigus marmoreus and Pleurotus eryngii induced secretion of IFN- gamma and IL-4 from T cells in a CD11c-positive cell-dependent manner similar to that of alpha-galactosylceramide (alpha-GalCer) and isoglobotriaosylceramide (iGb3), although activated T cells by AGLs showed less secretion of cytokine than those activated by alpha-GalCer. In addition, stimulation of these mushroom AGLs induced proliferation of NK1.1 alpha/beta TCR-double positive cells in splenocytes. Administration of a mixture of alpha-GalCer and AGLs affected the stimulation of alpha-GalCer and generally induced a subtle Th1 bias for splenocytes but induced an extreme Th2 bias for thymocytes. These results suggested that edible mushroom AGLs contribute to immunomodulation.

Immunogenic properties of mannose-containing ceramide disaccharide and immunochemical detection of its hapten in the two kinds of crustacean, Euphausia superba and Macrobrachium nipponense

Antiserum against Man beta 1-4Glc beta 1-1Ceramide (MIOse2Cer), a mannolipid isolated from spermatozoa of the fresh-water bivalve, Hyriopsis schlegellii, has been elicited in rabbits by repeated injection of a mixture of hapten-bovine serum albumin (1:1, mg/ml) with Freunds adjuvant. The specificity of the affinity-purified antibody (immunoglobulin G type) obtained from the serum was examined, using other glycosphingolipids and glyco-proteins structurally related to MIOse2Cer, by means of ELISA and TLC-immunostaining. The purified antibody was highly specific to MIOse2Cer and lacked reactivity with other glycolipids and glycoproteins including glucosylceramide, lactosylceramide, dimannosylglucosylceramide (MIOse3Cer), glucosaminylmannosylglucosylceramide (ArOse3Cer), thyroglobulin and alpha 1-acid glycoprotein. The antibody was found to bind, although less efficiently, to certain other compounds containing the group Man beta 1-4Glc and/or Man beta 1-4GlcNAc at their termini, such as MIOse2-sphingosine and Man beta 1-4GlcNAc beta 1-p-aminobenzoic acid ethylester derivatives. The present antibody was applied to the detection of the natural hapten in crustacean glycolipids. The purified antibody reacted with a neutral glycosphingolipid present in the two kinds of crustacean, Euphausia superba (antarctic krill) and Macrobrachium nipponense (fresh-water shrimp) as shown by TLC-immunostaining. The crustacean glycolipid antigen was isolated and characterized to be the Man beta 1-4Glc-Cer. This is the first report on the presence of a mannose-containing glycosphingolipid in the crustacean.

Biochemical studies on sphingolipids of Artemia franciscana: novel neutral glycosphingolipids.

Neutral glycosphingolipids containing one to six sugars in their oligosaccharide chains have been isolated from cysts of the brine shrimp Artemia franciscana. The structures of these glycolipids were identified by methylation analysis, partial acid hydrolysis, gas-liquid chromatography, combined gas-liquid chromatography-mass spectrometry, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and proton nuclear magnetic resonance spectroscopy to be Glcβ1-Cer, Manβ1-4Glcβ1-Cer, Fucα1-3Manβ1-4Glcβ1-Cer, GlcNAcβ1-3Manβ1-4Glcβ1-Cer, GlcNAcα1-2Fucα1-3Manβ1-4Glcβ1-Cer, GalNAcβ1-4GlcNAcβ1-3Manβ1-4Glcβ1-Cer, GalNAcβ1-4(Fucα1-3)GlcNAcβ1-3Manβ1-4Glcβ1-Cer (CPS), and GalNAcβ1-4(GlcNAcα1-2Fucα1-3)GlcNAcβ1-3Manβ1-4Glcβ1-Cer (CHS). Two glycosphingolipids, CPS and CHS, were characterized as novel structures. Because Artemia contains a certain series of glycosphingolipids (-Fucα3Manβ4GlcβCer), which differ from the core sugar sequences reported thus far, we tentatively designated the glycosphingolipids characterized as nonarthro-series ones. Furthermore, CHS exhibited a hybrid structure of arthro-series and nonarthro-series sugar chain. Two novel glycosphingolipids were characterized from the brine shrimp Artemia franciscana; one was composed of arthrotetraose and a branching fucose attached to N-acetylglucosamine residue, and the other was composed of CPS with an additional N-acetylglucosamine residue attached to the branching fucose.

Phosphocholine-Containing Glycosyl Inositol-Phosphoceramides from Trichoderma viride Induce Defense Responses in Cultured Rice Cells

We isolated two major zwitterionic glycosphingolipids (ZGLs) from the phytopathogenic filamentous fungus Trichoderma viride. Structural analyses showed that the ZGLs (designated Tv-ZGL2 and Tv-ZGL3) were the same as the glycosphingolipids ZGL2 and ZGL4 from Acremonium sp., which are described in our previous paper. ZGLs have the following structure: Man(α1-6)GlcN(α1-2)Ins-P-Cer (Tv-ZGL2) and phosphocholine (PC) → 6Man(α1-6)GlcN(α1-2)Ins-P-Cer (Tv-ZGL3). To determine whether these ZGLs have functional roles in plant-fungus interaction, we tested to determine whether they would induce defense responses in cultured rice cells. We found that T. viride’s ZGLs elicited expression of the PAL and PBZ1 genes, both of which are associated with pathogen resistance. Tv-ZGL2 induced cell death at a moderate rate. Tv-ZGL3, which contains a PC moiety, induced a high level of cell death in rice cells.

Biochemical studies on sphingolipids of Artemia franciscana: complex neutral glycosphingolipids

Brine shrimp are primitive crustacean arthropodal model organisms, second to daphnia, which can survive in high-salinity environments. Their oviposited cysts, cuticle-covered diapausing eggs, are highly resistant to dryness. To elucidate specialties of brine shrimp, this study characterized glycosphingolipids, which are signal transduction-associated material. A group of novel and complex fucosyl glycosphingolipids were separated and identified from cysts of the brine shrimp Artemia franciscana by repeated lipid extraction, alkaline methanolysis, acid treatment, successive column chromatography, and post-source decay measurements by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Structures of the glycosphingolipids were elucidated by conventional structural characterization and mass spectrometry, and the compounds were identified as GlcNAcβ1-3GalNAcβ1-4(GlcNAcα1-2Fucα1-3)GlcNAcβ1-3Manβ1-4Glcβ1-Cer, GalNAcβ1-4(Fucα1-3)GlcNAcβ1-3GalNAcβ1-4(GlcNAcα1-2Fucα1-3)GlcNAcβ1-3Manβ1-4Glcβ1-Cer, and GalNAcβ1-4(GlcNAcα1-2Fucα1-3)GlcNAcβ1-3GalNAcβ1-4(GlcNAcα1-2Fucα1-3)GlcNAcβ1-3Manβ1-4Glcβ1-Cer. These compounds also contained a branching, non-arthro-series disaccharide with an α-GlcNAc terminus, similar to that found in a previously reported ceramide hexasaccharide (III3(GlcNAcα2Fucα)-At4Cer). The glycans within these complex GSLs are longer than reported glycans of the animal kingdom containing α-GlcNAc terminus. These complex GSLs as well as the longest GSL with ten sugar residues, ceramide decasaccharide (CDeS), contain the fucosylated LacdiNAc sequence reported to associate with parasitism/immunosuppression and the α-GlcNAc terminus reported to show a certain antibacterial effect in other reports. CDeS, the longest GSL of this species, was found in the highest amount, which indicates that CDeS may be functionally important.

Structural analysis of cerebrosides from Aspergillus fungi: the existence of galactosylceramide in A. oryzae

Glucosylceramide and galactosylceramide were detected in three Aspergillus species: Aspergillus oryzae, Aspergillus sojae and Aspergillus. awamori, using borate-coated TLC. The cerebrosides from A. oryzae were further purified by ion exchange and iatrobeads column chromatographies with or without borate, and determined the composition of sugar, fatty acid and sphingoid base by GC/MS, MALDI-TOF/MS and 1H-NMR. We identified them as β-glucosylceramide and β-galactosylceramide. The ceramide moiety of both cerebrosides consisted mainly of 2-hydroxystearic acid and either 9-methyl-octadeca-4, 8-sphingadienine or octadeca-4, 8-sphingadienine. To our knowledge, this is the first study to provide evidence for the presence of β-galactosylceramide in A. oryzae.

Isolation and characterization of a novel uronic acid-containing acidic glycosphingolipid from the ascidian Halocynthia roretzi

A novel uronic acid-containing glycosphingolipid (UGL-1) was isolated from the ascidian Halocynthia roretzi. UGL-1 was prepared from chloroform-methanol extracts and purified by the use of successive column chromatography on DEAE-Sephadex, Florisil, and Iatrobeads. Chemical structural analysis was performed using methylation analysis, gas chromatography, gas chromatography-mass spectrometry, matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry, and 1H-NMR spectra. The chemical structure of UGL-1 was determined to be a glucuronic acid-containing glycosphingolipid, Galβ1-4(Fucα1-3)GlcAβ1-1Cer. The ceramide component was composed of C16:0 and C18:0 acids and C16-, C17-, and C18-phytosphingosines as major components.

Ceramide aminoethylphosphonate from jumbo flying squid Dosidicus gigas attenuates the toxicity of cyanotoxin microcystin-LR

We have previously established the method for isolation of ceramide aminoethylphosphonate (CAEP) from jumbo flying squid Dosidicus gigas. In this study, we performed a MTT assay to evaluate the safety of CAEP to the cell lines for the application to health food and supplements. The CAEP did not show any cytotoxicity to various HEK293-transfectant cells. Next, we elucidated the positive function of CAEP to the somatic cells. Recently, we have reported that hepatotoxin microcystin-LR was taken up into the hepatocytes mediated by hepatocellular uptake transporters OATP1B1 and OATP1B3, and the cells were induced cytotoxicity subsequently. Cytotoxicity of microcystin-LR to permanently OATP1B3-expressing HEK293-OATP1B3 cells rather than to HEK293-OATP1B1 cells was preferentially attenuated by CAEP in a concentration-dependent manner. In addition, the enzyme activity of serine/threonine phosphatase, which was inhibited by microcystin-LR, was recuperated by co-exposure to CAEP. Furthermore, microcystin-LR-induced cellular protein phosphorylation were disrupted by CAEP exposure. These results suggested that CAEP is a promising remedy and/or preventive medicine for liver damage with microcystin-LR.

Biochemical Studies on Sphingolipid of Artemia franciscana (I) Isolation and Characterization of Sphingomyelin

Sphingomyelin was isolated from cysts of the brine shrimp Artemia franciscana using QAE-Sephadex A25, Florisil and Iatrobeads column chromatographies. The chemical structure was identified using thin-layer chromatography, gas–liquid chromatography, infrared spectroscopy and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The ceramide moiety of sphingomyelin consisted of stearic, arachidic, and behenic acids as fatty acids, and hexadeca-4- and heptadeca-4-sphingenines as sphingoids. By comparative analysis, the ceramide component of Artemia sphingomyelin appears unique in invertebrates and vertebrates. Biological functions of sphingomyelin have largely been investigated using mammalian-derived sphingomyelin. In mammals, a wide variety of molecular species of sphingomyelins have been reported, especially derived from nerve tissue, while the lower animal Artemia contains this unusual sphingomyelin perhaps because of having a much simpler nervous system. The purified unusual sphingomyelin derived from Artemia franciscana might be a very useful tool in elucidating the functions and mechanisms of action of this mediator.