Glycosylation, the most abundant posttranslational modification, holds an unprecedented capacity for altering biological function. Our ability to harness glycosylation as a means to control biological systems is hampered by our inability to pinpoint the specific glycans and corresponding biosynthetic enzymes underlying a biological process. Herein we identify glycosylation enzymes acting as regulatory elements within a pathway using microRNA (miRNA) as a proxy. Leveraging the target network of the miRNA-200 family (miR-200f), regulators of epithelial-to-mesenchymal transition (EMT), we pinpoint genes encoding multiple promesenchymal glycosylation enzymes (glycogenes). We focus on three enzymes, beta-1,3-glucosyltransferase (B3GLCT), beta-galactoside alpha-2,3-sialyltransferase 5 (ST3GAL5), and (alpha-N-acetyl-neuraminyl-2,3-beta-galactosyl-1,3)-N-acetylgalactosaminide alpha-2,6-sialyltransferase 5 (ST6GALNAC5), encoding glycans that are difficult to analyze by traditional methods. Silencing these glycogenes phenocopied the effect of miR-200f, inducing mesenchymal-to-epithelial transition. In addition, all three are up-regulated in TGF-β–induced EMT, suggesting tight integration within the EMT-signaling network. Our work indicates that miRNA can act as a relatively simple proxy to decrypt which glycogenes, including those encoding difficult-to-analyze structures (e.g., proteoglycans, glycolipids), are functionally important in a biological pathway, setting the stage for the rapid identification of glycosylation enzymes driving disease states.

Cell surface glycans form a critical interface with the biological milieu, informing diverse processes from the inflammatory cascade to cellular migration. Assembly of discrete carbohydrate structures requires the coordinated activity of a repertoire of proteins, including glycosyltransferases and glycosidases. Little is known about the regulatory networks controlling this complex biosynthetic process. Recent work points to a role for microRNA (miRNA) in the regulation of specific glycan biosynthetic enzymes. Herein we take a unique systems-based approach to identify connections between miRNA and the glycome. By using our glycomic analysis platform, lectin microarrays, we identify glycosylation signatures in the NCI-60 cell panel that point to the glycome as a direct output of genomic information flow. Integrating our glycomic dataset with miRNA data, we map miRNA regulators onto genes in glycan biosynthetic pathways (glycogenes) that generate the observed glycan structures. We validate three of these predicted miRNA/glycogene regulatory networks: high mannose, fucose, and terminal β-GalNAc, identifying miRNA regulation that would not have been observed by traditional bioinformatic methods. Overall, our work reveals critical nodes in the global glycosylation network accessible to miRNA regulation, providing a bridge between miRNA-mediated control of cell phenotype and the glycome.

Microvesicles (exosomes) are important mediators of intercellular communication, playing a role in immune regulation, cancer progression, and the spread of infectious agents. The biological functions of these small vesicles are dependent on their composition, which is regulated by mechanisms that are not well understood. Although numerous proteomic studies of these particles exist, little is known about their glycosylation. Carbohydrates are involved in protein trafficking and cellular recognition. Glycomic analysis may thus provide valuable insights into microvesicle biology. In this study, we analyzed glycosylation patterns of microvesicles derived from a variety of biological sources using lectin microarray technology. Comparison of the microvesicle glycomes with their parent cell membranes revealed both enrichment and depletion of specific glycan epitopes in these particles. These include enrichment in high mannose, polylactosamine, α-2,6 sialic acid, and complex N-linked glycans and exclusion of terminal blood group A and B antigens. The polylactosamine signature derives from distinct glycoprotein cohorts in microvesicles of different origins. Taken together, our data point to the emergence of microvesicles from a specific membrane microdomain, implying a role for glycosylation in microvesicle protein sorting.

Herein we describe the orientation of GST-tagged lectins on NHS-activated slides via a one-step deposition of the protein and a glutathione (GSH) scaffold. This technology overcomes the need for a premade GSH-surface to orient GST-tagged proteins, enabling us to rapidly expand the analytical capacity of lectin microarrays through addition of oriented lectins, while maintaining lectin diversity.

Glycosylation, a ubiquitous post-translational modification of proteins and lipids that generates enormous functional diversity, is rapidly gaining attention in the postgenomic era. The systematic study of glycans, that is glycomics, has been driven by the development of new analytical tools well suited to the inherent complexities of carbohydrate analysis, such as lectin-based microarray technologies. Recent work has demonstrated the utility of these analytical tools for glycomics in both clinical and research settings, for example identifying novel biomarkers associated with disease progression or studying HIV-1 exit mechanisms. This review highlights these new lectin-based microarray technologies and their role in the emerging field of glycomics.

Carbohydrates encode biological information necessary for cellular function. The structural diversity and complexity of these sugar residues have necessitated the creation of novel methodologies for their study. This review highlights recent technological advancements that are starting to unravel the intricate web of carbohydrate biology. New methods for the analysis of both glycoconjugates and glycan structures are discussed. With the use of these innovative tools, the field of glycobiology is poised to take center-stage in the postgenomic era of modern biology and medicine.Keywords: Biomarkers: biomolecules that are altered in certain disease states and could be used as diagnostic markers to indicate disease progression; Glycans: simple or complex polymers composed of monosaccharides; Glycoconjugates: biomolecules which are modified with glycans such as lipids and proteins; Glycome: the cohort of glycans and glycoconjugates found in a system; Glycoproteomics: isolation and identification of glycosylated proteins from a complex mixture; Lectins: carbohydrate binding proteins that are not antibodies or enzymes; Mass spectrometry: analytical technique that relies on unique mass signatures to identify components of a complex sample; Microarrays: collection of probes immobilized on a solid support for high-throughput sample analysis