Structural analysis of brain ganglioside acetylation patterns in mice with altered ganglioside biosynthesis

Abstract

Gangliosides are sialylated membrane glycosphingolipids especially abundant in mammalian brain tis-sue. Sialic acid O-acetylation is one of the most common structural modifications of gangliosides which considerably influences their chemical properties. In this study, gangliosides extracted from brain tissue of mice with altered ganglioside biosynthesis (St8sia1 null and B4galnt1 null mice) were structurally characterized and their acetylation pattern was analyzed. Extracted native and alkali-treated gangliosides were resolved by high performance thin layer chromatography. Ganglioside mixtures as well as separated individual ganglioside fractions were further analyzed by tandem mass spectrometry. Several O-acetylated brain ganglioside species were found in knockout mice, not present in the wild-type mice. To the best of our knowledge this is the first report on the presence of O-acetylated GD1a in St8sia1 null mice and O-acetylated GM3 species in B4galnt1 null mice. In addition, much higher diver-sity of abnormally accumulated brain ganglioside species regarding the structure of ceramide portion was observed in knockout versus wild-type mice. Obtained findings indicate that the diversity of brain ganglioside structures as well as acetylation pat-terns in mice with altered ganglioside biosynthesis, is even higher than previously reported. Further investigation is needed in order to explore the effects of acetylation on ganglioside interactions with other molecules and consequently the physiological role of acetylated ganglioside species.

Characterization and Modeling of the Collision Induced Dissociation Patterns of Deprotonated Glycosphingolipids: Cleavage of the Glycosidic Bond

“…Details about extraction and purification procedures can be found in the original publications [10,16]. Negative ion mode MS and tandem MS analysis of the GSL samples were performed on the Bruker amaZon ETD ion trap system (Bruker Daltonik GmbH, Bremen, Germany) using the experimental procedure described in the previous publications [10,16]. GSL ion identification was accomplished using the software application BGSL finder^and its accompanying GSL database [16].…”

“…by tandem mass spectrometry (MS/MS) techniques has become an important part of the analytical approach to the analysis of the glycome [1][2][3][4][5][6][7][8][9][10]. In a typical scenario, glycoconjugates are ionized by electrospray ionization or matrix-assisted laser desorption ionization and subsequently analyzed by examining measured mass and collision induced dissociation (CID) spectra [1][2][3][4][5][6][7][8][9][10]. In order to optimize the application of the technique, it is important to understand the gas-phase ion chemistry of the dissociation reactions of glycoconjugates.…”

“…The database and accompanying application (GSL-finder) have been successfully applied to the analysis of mice brain gangliosides (sialic acid (Neu5Ac) containing glycosphingolipids) with altered ganglioside biosynthesis, on a commercially available ganglioside fraction, and on complex native ganglioside mixtures isolated from human (fetal and adult) and calf brain tissues [10,16]. The GSL-finder application and other software tools for mass spectrometric data analysis of glycoconjugates are designed to assign molecular structures to tandem MS spectra [16][17][18].…”

“…A small data set of 75 tandem MS spectra collected from previous studies [10,16] was used to suggest fragmentation behavior of GSLs. The proposed fragmentation pathways have been computationally assessed on a GSL level.…”

Database and data analysis application for structural characterization of gangliosides and sulfated glycosphingolipids by negative ion mass spectrometry

“…Additionally, we have recently successfully applied the GSL-finder to the analysis of brain gangliosides from mice with altered ganglioside biosynthesis. 42 …”