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Golgi membrane protein 1 (GOLM1) is a Golgi-resident type 2 transmembrane protein known to be overexpressed in several cancers, including he-patocellular carcinoma (HCC), as well as in viral in-fections. However, the role of GOLM1 in lipid metabolism remains enigmatic. In this study, we employed siRNA-mediated GOLM1 depletion in Huh -7 HCC cells to study the role of GOLM1 in lipid metabolism. Mass spectrometric lipidomic analysis in GOLM1 knockdown cells showed an aberrant accu-mulation of sphingolipids, such as ceramides, hex-osylceramides, dihexosylceramides, sphinganine, sphingosine, and ceramide phosphate, along with cholesteryl esters. Furthermore, we observed a reduction in phosphatidylethanolamines and lyso-phosphatidylethanolamines. In addition, Seahorse extracellular flux analysis indicated a reduction in mitochondrial oxygen consumption rate upon GOLM1 depletion. Finally, alterations in Golgi struc-ture and distribution were observed both by electron microscopy imaging and immunofluorescence mi-croscopy analysis. Importantly, we found that GOLM1 depletion also affected cell proliferation and cell cycle progression in Huh-7 HCC cells. The Golgi structural defects induced by GOLM1 reduction might potentially affect the trafficking of proteins and lipids leading to distorted intracellular lipid ho-meostasis, which may result in organelle dysfunction and altered cell growth. In conclusion, we demon-strate that GOLM1 depletion affects sphingolipid metabolism, mitochondrial function, Golgi structure, and proliferation of HCC cells.

International audience; Atherogenic LDL particles are physicochemically and metabolically heterogeneous. Can bioactive lipid cargo differentiate LDLsubclasses, and thus potential atherogenicity? What is the effect of statin treatment? Obese hypertriglyceridemic hypercholesterolemicmales [n = 12; lipoprotein (a)

Glycosphingolipids (GSLs) were purified from adults and plerocercoids of the tapeworm Diphyllobothrium hottai, and their chemical structures were determined. Total lipid fractions prepared from chloroform/methanol extracts of whole tissues were fractionated successively on ion-exchange chromatography, silicic acid column chromatography, and preparative TLC. The purified GSLs were characterized by methylation analysis, TLC-immunostaining, liquid secondary ion MS, MALDI-TOF MS, and 1H-NMR. Ten GSLs were isolated from adult worms and four from plerocercoids, comprising mono-, di-, tri-, tetra-, and pentasaccharides. The GSL Galβ1–4(Fucα1–3)Glcβ1–3Galβ1-Cer was found in adult worms but not in plerocercoids, whereas Galβ1–4 (Fucα1–3)Glcβ1–3(Galβ1–6)Galβ1-Cer was found in both adult worms and plerocercoids. We previously found a similar series of GSLs in plerocercoids of the cestode Spirometra erinaceieuropaei, and termed them ‘spirometosides’[Kawakami, Y. et al. (1996) Eur J. Biochem. 239, 905–911]. The core structure of spirometosides, Galβ1–4Glcβ1–3 Galβ1-Cer, may have taxonomic significance, being characteristic of pseudophyllidean tapeworms. In the present study, GSL compositions were significantly different between adults and plerocercoids, and growth-dependent changes in composition were documented. We found a novel dihexosylceramide, Glcβ1–3Galβ1-Cer, which is a possible precursor for spirometosides. Immunohistochemical examination showed that spirometoside GSLs are highly enriched in the inner surface of bothria, the major point of contact between the adult worm and the host's intestine. Our findings indicate that spirometosides are involved in host–parasite interaction.

1. 1. Glycosphingolipids have been isolated from rat sublingual and submaxillary glands by the procedure involving lipid extraction, column fractionation and thin-layer chromatography. 2. 2. The major neutral glycosphingolipids in rat sublingual and submaxillary glands were monohexosylceramide, dihexosylceramide, tetrahexosylceramide and pentahexosylceramide. Both types of glands exhibited a low content of trihexosylceramide. The fucose-containing glycosphingolipids were not found. 3. 3. The acidic glycosphingolipids in rat sublingual and submaxillary glands were composed of monohexose sulfatide, dihexose sulfatide and monosialoand disialogangliosides of hematoside series. In addition, small quantities of gangliosides containing hexosamines were also present. 4. 4. The distribution of acidic and neutral glycosphingolipids was similar in the sublingual and submaxillary glands, except for the tetrahexosylceramide and sultatides. Sublingual glands contained 1.5 and 3.0 times as much tetrahexosylceramide and sulfatides, respectively, as did submaxillary glands. 5. 5. The glycosphingolipids of submaxillary and sublingual glands showed large similarity in fatty acid composition. The fatty acid composition of gangliosides resembled each other, but differed remarkably from those of sulfatides and neutral glycosphingolipids in the docosanoate content.

— Purified oligodendroglia isolated from bovine brain white matter were found to contain, in addition to galactosylceramide, sulfatide and sphingomyelin, significant quantities of glucosylcerai-mide, dihexosylceramide and esterified galactosylceramide. These sphingolipids were isolated and quan-titated and their fatty acid and long chain base patterns compared with those from sphingolipids isolated from bovine myelin, white matter and gray matter. The minor glycosphingolipids, glucosylceramide, dihexosylceramide and esterified galactosylceramide, constituted a higher percentage of glial lipids than of myelin lipids. Glucosylceramide accounted for 12% of the total glial monohexosylceramide fraction and 0.8% of total lipids; dihexosylceramide was 0.9% of total glial lipids. Both of these lipids had small quantities of α-hydroxy fatty acids. The unsubstituted fatty acids of glucosylceramide were mostly short chain (16 and 18 carbons) and were different from those of the dihexosylceramides which were a mixture of short and long chain. The hydroxy acids of each of these lipids were, however, similar and resembled those of galactosylceramide. The fatty acid patterns of galactosylceramide, sulfatide and sphingomyelin from glial cells resembled those of the corresponding lipids from myelin and white matter. The amide-linked acids of esterified galactosylceramide contained both unsubstituted and α-hydroxy chains. Their patterns were not identical to those of galactosylceramide, but were similar in all brain fractions. With the exception of sphingomyelin and dihexosylceramide, which contained small amounts of C20-sphingosine, all sphingolipids analyzed contained mostly sphingosine and dihydrosphingosine. We conclude that the distribution of sphingolipids in the oligodendroglia is characteristic, but the lipophilic residues of these lipids are not cell-specific.

— Dihexosylceramide from the brain of a case of globoid cell leukodystrophy was isolated and characterized. Studies utilizing partial acid hydrolysis and methylation indicated the carbohydrate sequence to be galactosylglucosylceramide. The carbohydrate moiety was liberated by ozonolysis and identified to be lactose by GLC. 4-Sphingenine and sphinganine were the only long chain bases detected. The chain length of the fatty acids present ranged from 14 to 25 carbons; C18, and C21 fatty acids composed one-half of the mixture. All analyses were performed by GLC and TLC utilizing micro-techniques.