Abstract
Gangliosides, a member of the glycosphingolipid family, are heterogeneously expressed in biological membranes and are particularly enriched within the central nervous system. Gangliosides consist of mono- or poly-sialylated oligosaccharide chains of variable lengths attached to a ceramide unit and are found to be intimately involved in brain disease development. The purpose of this study is to examine the spatial profile of ganglioside species using matrix-assisted laser desorption/ionization (MALDI) imaging (IMS) following middle cerebral artery occlusion (MCAO) reperfusion injury in the mouse. IMS is a powerful method to not only discriminate gangliosides by their oligosaccharide components, but also by their carbon length within their sphingosine base. Mice were subjected to a 30 min unilateral MCAO followed by long-term survival (up to 28 days of reperfusion). Brain sections were sprayed with the matrix 5-Chloro-2-mercaptobenzothiazole, scanned and analyzed for a series of ganglioside molecules using an Applied Biosystems 4800 MALDI TOF/TOF. Traditional histological and immunofluorescence techniques were performed to assess brain tissue damage and verification of the expression of gangliosides of interest. Results revealed a unique anatomical profile of GM1, GD1 and GT1b (d18∶1, d20∶1 as well as other members of the glycosphingolipid family). There was marked variability in the ratio of expression between ipsilateral and contralateral cortices for the various detected ganglioside species following MCAO-reperfusion injury. Most interestingly, MCAO resulted in the transient induction of both GM2 and GM3 signals within the ipsilateral hemisphere; at the border of the infarcted tissue. Taken together, the data suggest that brain region specific expression of gangliosides, particularly with respect to hydrocarbon length, may play a role in neuronal responses to injury.
Highlights
Gangliosides are a member of the glycosphingolipid family and consist of mono- to poly-sialylated oligosaccharide chains attached to a ceramide base
The ceramide moieties of gangliosides are heterogeneous with respect to carbon chain length within their sphingosine base
Imaging matrix-assisted laser desorption/ionization (MALDI)-TOF detection of gangliosides within the mouse brain Adjacently sectioned coronal mouse brain sections were stained with Cresyl Violet to determine the neuroanatomical regions to be selected for regions of interest (ROIs)
Summary
Gangliosides are a member of the glycosphingolipid family and consist of mono- to poly-sialylated oligosaccharide chains attached to a ceramide base. Gangliosides, GM1, have been identified as a major lipid constituent of membrane rafts in many cell types [5,6]. Gangliosides have a wide range of CNS functions including membrane function [7], axon stability and regeneration [8], differentiation [9] and neurodegeneration [10,11,12]. The ceramide moieties of gangliosides are heterogeneous with respect to carbon chain length within their sphingosine base. It has been suggested that d18:1 and d20:1 gangliosides are differentially regulated and may possess unique roles with respect to neuronal function and cell death [13,14]
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