Exploring the role of sialic acid in the glycoprotein LFA-1 using bioconjugate chemistry

The lymphocyte function associated antigen-I (LFA-1) is important to a variety of immune cell processes including immune synapse formation and lymphocyte homing. Studies have shown that lymphocytes exhibit increased adhesion upon sialic acid removal by neuraminidase. Recent studies of β1 integrin function have shown a role for sialic acid. We hypothesized that modifications to sialic acids on LFA-1 may influence ligand binding, as a potential mechanism responsible for the neuraminidase effect. Herein, we describe progress towards studying LFA-1 sialic acids and their role in LFA-1 mediated adhesion. We describe applications of metabolic labeling strategies. We demonstrate bioconjugation of alkynyl drag-tags for resolution of sialoforms of metabolicallylabeled murine IgG. We demonstrate bioconjugation of synthetic carbohydrate epitopes to an azide-containing model protein by Staudinger ligation. Finally, we report the production of stable HeLa cell lines expressing GFP-fused NEU3, as a model system for in vivo studies of NEU3.