Novel glycan-related biomarker discovery by total glycomic and focused protein glycomic analyses

The cell surface is covered with a variety of glycan subtypes (sub-glycans) such as N-glycans, O-glycans, glycosphingolipid-glycans, and glycosaminoglycans, which are collectively called the glycocalyx. The expression patterns of sub-glycans change in response to various biological events during disease pathogenesis; however, the structures of all major sub-glycans and their relative concentrations in a cell have been hardly reported. Total glycomic analysis, which comprehensively measures all major sub-glycans, is a powerful tool to discover cellular and clinical biomarkers. In this review, we provide an overview of the analytical methods for sub-glycans and the total glycome in cultured cell lines, human serum, mouse brain tissue, and human osteoarthritis cartilage. This approach not only facilitates characterization of cells, but also has applications for hierarchical clustering analysis, glycan-related biomarker discovery, and investigation of the relationship between sub-glycans and gene expression levels using the total glycome. Moreover, we discuss our recent research focused on identifying potential biomarkers of nonalcoholic fatty liver disease. These glycomic technologies are expected to contribute to diagnostics and drug development for rare diseases in the future.