INTRODUCTION: Sialylation is a post-translational modification of molecules by adding sialic acid. Dysregulated sialylation influences the immune response and is observed in diseases such as Multiple Sclerosis (MS). Astrocytes and microglia regulate de- and remyelination, and dysregulated activation of these cells drives MS progression. Our unpublished data show that especially α-2.6 sialylation increases in astrocytes and microglia in the cuprizone mouse model of MS.

AIM(S): This study aims to characterize the α-2.6 sialylation profiles of astrocyte and microglial cell lines, with a primary interest in differences in sialylation patterns that may explain molecular mechanisms of glial dysregulation in MS pathology.

METHOD(S): We used murine BV-2 (microglia) and C8-D1A (astrocytes) cells. α-2.6 sialylation was assessed with Sambucus nigra agglutinin - α2,6-linked sialic acids binding protein (SNA lectin). Comparative α-2.6 sialylation patterns between BV-2 and C8-D1A cells were evaluated using immunofluorescence staining. We also compare, by Western blotting, protein levels of enzymes involved in sialic acid metabolism, including sialyltransferase ST6GAL1 and neuraminidase 1 (NEU1). Intracellular localization of those proteins was characterized using specific antibodies and high-resolution confocal microscopy.

RESULTS: Both BV-2 and C8-D1A cells showed prominent α2,6-sialylation. NEU1 was strongly expressed and localized at the cell membrane surface, but also intracellular in the lysosomes. Sialyltransferase ST6GAL1 was observed in the Golgi apparatus, with no differences in the protein level between glial cells. We also observed that most of α2,6-sialylated proteins are localized mainly in the Golgi apparatus.

CONCLUSIONS: Integrating glycobiology with glial biology, this study highlights the role of glycosylation in glial function and suggests mechanisms underlying neuroinflammation and neurodegeneration. These cells provide suitable in vitro models for studying cell-specific glycosylation and its functional consequences.

FINANCIAL SUPPORT: Research funded by the Department of Biochemistry, Faculty of Biotechnology at the University of Wrocław.