Design of Oligosaccharide Libraries to Characterize Heparan Sulfate – Protein Interactions

Abstract: Heparan sulfates (HSs) are a class of anionic carbohydrate chains found at cell surfaces and in the extracellular matrix where they interact with a number of proteins. HS is characterized by extreme structural heterogeneity, and has been implicated in a number of biological phenomenon like embryogenesis, morphogen gradient formation and signalling of growth factors such as FGF, PDGF etc. Despite the characteristic structural heterogeneity, evidence from compositional studies show that the HS structure is expressed in a tightly regulated manner, implying a functional significance, which is most likely in the modulation of cell behaviour through HS-protein interactions. The lack of molecular tools has, however, hampered the understanding of HS structures with functional significance. This work therefore aims at characterizing the structural requirements on HS involved in the interaction with the anti-HS phage display antibodies HS4C3, AO4B08 and HS4E4 and a selected growth factor PDGF-BB. The characterization was done with the help of tailored oligosaccharide libraries generated from sources bearing structural resemblance to HS.The work has thus made available tools that preferentially recognize certain structural features on the HS chain and will aid in the further study of HS structure and its regulation. Evidence is also provided to support the notion that HS protein interactions can occur in multiple manners, utilizing any of the structural features on the HS chain.