MS characterization of total cellular proteome in responses to exogenous sugar stress

Abstract

Glucosamine (GlcN) and N-Acetylglucosamine (GlcNAc) are sugar metabolites of the hexosamine biosynthesis pathway (HBP) in which glucose is converted to the nucleotide sugar uridine diphosphate N-acetylglucosamine (UDP-GlcNAc). The HBP, conserved across all eukaryotes, is involved in many cellular processes such as protein glycosylation, signal transduction, and gene expression regulation. Protein glycosylation, particularly, is a post-translational modification vital for substrate specificity and protein-protein recognition in membrane proteins and receptors, thus critical for immune system regulation. Since both GlcN and GlcNAc are produced from the same pathway and share similar structures and properties, they are often used interchangeably to study the HBP. While GlcN is significantly more studied, there are very few studies focusing on GlcNAc. However, our study provides a different perspective. Using the wound healing assay to assess cell migration rates, we noticed significant differences in cell responses between those treated with GlcN and GlcNAc: cells migrated faster or no change (depending on the glucose condition) as GlcNAc concentration increased and migrated slower as GlcN concentration increased (regardless of the glucose condition). In addition, other cell properties such as cell-to-cell adhesion and cell morphology were altered distinctly in cells exposed to GlcN and GlcNAc. These findings carry significant implications for immune response, vascular health, diabetes, as well as cancer metastasis. I will further study the altered proteome to gain insight on the molecular mechanisms through which exogenous GlcN and GlcNAc influence cell behaviours.