Electronic Thesis and Dissertation Repository

Degree

Master of Science

Program

Anatomy and Cell Biology

Supervisor

Shawn Whitehead

2nd Supervisor

Gilles Lajoie

Co-Supervisor

Abstract

With aging, our brains become more susceptible to disease and injury. Different regions of the brain have differing levels of vulnerability to stress and injury, and this brain region-dependent variability to vulnerability could be partly explained by the existence of glycosphingolipids within the cell’s plasma membrane called gangliosides. Gangliosides are expressed predominantly within the brain and play various roles within the central nervous system including neural repair, cell survival, and neurodegeneration. Our laboratory has demonstrated that gangliosides can shift their composition from GM1 back to GM2 and GM3 following stroke in mice and rats indicating a role for simple gangliosides in the neurodegenerative process and this shift may be part of a neuro-inflammatory cascade. However, to date, ganglioside analysis in microglia cells has not yet been done. Based on the literature and preliminary studies conducted in our laboratory, we hypothesized that GM1, GM2 and GM3 levels will change during microglia activation. BV2 cells were cultured and cells were treated with lipopolysaccharide (LPS) and interleukin 4 (IL-4) to induce M1 and M2 activation, respectively. Liquid chromatography electrospray ionization mass spectrometry LC-ESI-MS was used to quantify ganglioside levels following activation, and immunofluorescence was used to stain for GM1, GM2 and GM3 gangliosides. RT-qPCR was performed to verify what phenotypes were activated in response to observed changes in gangliosides. Our results showed a significant increase in GM1, GM2 and GM3 gangliosides in M1 BV2 cells while no change was observed in the M2 phenotype. RT-qPCR results showed a significant peak in M1 markers at 24 h following LPS while M2 markers peaked at 8 h following IL-4 exposure. Our in vitro results suggest that M1 phenotype could be selectively targeted to understand ganglioside changes following injury and that M1 microglia can be the source of the transient increase in GM1, GM2 and GM3 found in animal models of neurodegeneration

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