Low and high affinity receptors mediate cellular uptake of heparanase.

Heparanase is an endoglycosidase which cleaves heparan sulfate and hence participates in degradation and remodeling of the extracellular matrix. Importantly, heparanase activity correlated with the metastatic potential of tumor-derived cells, attributed to enhanced cell dissemination as a consequence of heparan sulfate cleavage and remodeling of the extracellular matrix barrier. Heparanase has been characterized as a glycoprotein, yet glycan biochemical analysis was not performed to date. Here, we applied the Qproteometrade mark GlycoArray kit to perform glycan analysis of heparanase, and compared the kit results with the more commonly used biochemical analyses. We employed fibroblasts isolated from patients with I-cell disease (mucolipidosis II), fibroblasts deficient of low density lipoprotein receptor-related protein and fibroblasts lacking mannose 6-phosphate receptor, to explore the role of mannose 6-phosphate in heparanase uptake. Iodinated heparanase has been utilized to calculate binding affinity. We provide evidence for hierarchy of binding to cellular receptors as a function of heparanase concentration. We report the existence of a high affinity, low abundant (i.e., low density lipoprotein receptor-related protein, mannose 6-phosphate receptor), as well as a low affinity, high abundant (i.e., heparan sulfate proteoglycan) receptors that mediate heparanase binding, and suggest that these receptors co-operate to establish high affinity binding sites for heparanase, thus maintaining extracellular retention of the enzyme tightly regulated.

A lectin array-based methodology for the analysis of protein glycosylation.

Glycosylation is the most versatile and one of the most abundant protein modifications. It has a structural role as well as diverse functional roles in many specific biological functions, including cancer development, viral and bacterial infections, and autoimmunity. The diverse roles of glycosylation in biological processes are rapidly growing areas of research, however, Glycobiology research is limited by the lack of a technology for rapid analysis of glycan composition of glycoproteins. Currently used methods for glycoanalysis are complex, typically requiring high levels of expertise and days to provide answers, and are not readily available to all researcher. We have developed a lectin array-based method, Qproteome GlycoArray kits, for rapid analysis of glycosylation profiles of glycoproteins. Glycoanalysis is performed on intact glycoproteins, requiring only 4-6 h for most analysis types. The method, demonstrated in this manuscript by several examples, is based on binding of an intact glycoprotein to the arrayed lectins, resulting in a characteristic fingerprint that is highly sensitive to changes in the protein's glycan composition. The large number of lectins, each with its specific recognition pattern, ensures high sensitivity to changes in the glycosylation pattern. A set of proprietary algorithms automatically interpret the fingerprint signals to provide a comprehensive glycan profile output.