engleski

Acetylation patterns of gangliosides in brain tissue of ganglioside-deficient mice

Gangliosides are sialylated glycosphingolipids especially abundant in mammalian nervous system. With their carbohydrate moiety protruding from the cell, gangliosides interact with opposing cells and molecules of the extracellular matrix. One of the most common covalent modifications of gangliosides is O-acetylation of sialic acids which results in considerable changes in their physiological properties. In order to investigate acetylation patterns of gangliosides we used genetically modified mouse models which lack ganglioside biosynthetic enzymes, St8sia1 null and B4galnt1 null. Total concentration of brain gangliosides was the same in mouse models and wild-type mice ; however mice with disrupted St8sia1 gene lack b- and c-series while they accumulate a-series gangliosides. B4galnt1 null mice lack all complex gangliosides accumulating just GM3 and GD3. We performed structural analysis of accumulated ganglioside species with focus on acetylation pattern in brain tissue of ganglioside-deficient mice. The gangliosides were extracted and separated using high performance thin layer chromatography. Alkali treatment was performed in parallel to determine the presence of O-acetylated ganglioside species. Separated ganglioside fractions were further analyzed by tandem mass spectrometry. We found several O-acetylated ganglioside species in ganglioside-deficient mice not present in the wild-type mice. In B4galnt1 null mice we confirmed the presence of previously reported O-acetylated GD3, but also O-acetylated GM3 species was detected, while in St8sia1 null mice O-acetylated GD1a was found. Although ganglioside-deficient mice have been used in research for years, structural composition of accumulated gangliosides has not been fully investigated. Since changed O-acetylation pattern could potentially contribute to altered ganglioside interactions with other molecules, this is a good model to explore the effects of acetylation on ganglioside function in crucial cellular events.

Brain gangliosides; acetylation

nije evidentirano