Modulating Heparanase Activity: Tuning Sulfation Pattern and Glycosidic Linkage of Oligosaccharides

Abstract

Heparanase cleaves polymeric heparan sulfate (HS) molecules into smaller oligosaccharides, allowing for release of angiogenic growth factors promoting tumor development and autoreactive immune cells to reach the insulin-producing β cells. Interaction of heparanase with HS chains is regulated by specific substrate sulfation sequences. We have synthesized eleven trisaccharides that are highly tunable in structure and sulfation pattern, allowing us to determine how heparanase recognizes HS substrate and selects a favorable cleavage site. Our study shows that ( 1) N-SO 3 − at +1 subsite and 6-O-SO 3 − at −2 subsite of trisaccharides are critical for heparanase recognition; (2) addition of 2-O-SO 3 − at the −1 subsite and of 3-O-SO 3 − to GlcN unit is not advantageous; and (3) the anomeric configuration (α or β) at the reducing end is crucial in controlling heparanase activity. Our study also illustrates that the α-trisaccharide having Nand 6-O-SO 3 − at −2 and +1subsites inhibited heparanase and was resistant toward hydrolysis.

Heparan Sulfate: A Regulator of White Adipocyte Differentiation and of Vascular/Adipocyte Interactions

“…Sulfatases are a family of enzymes that mediate the selective removal of sulfate groups from HS chains [ 26 ]. Two heparanases mediate the cleavage of specific carbohydrate linkages, thus releasing fragments of the HS chain [ 31 ]. Individuals with type I diabetes exhibit high levels of heparanases activity resulting in poorly sulfated HS associated with β-cells [ 32 ].…”

“…Additionally, elevated glucose activates inflammatory cells resulting in inflamed adipose tissues characteristic of obese individuals. These enzymes become important in diabetic individuals as the size and sulfation of HS are modified by glucose levels [ 31 ]. The HS-modifying enzymes found in adipose tissues are the same as found elsewhere; however, it is possible that their regulation is modified.…”

“…Aubin et al [ 71 ] added tumor necrosis factor-α to the culture medium and found a modification in the release of adipokines into the culture medium. High glucose levels have been shown to modify the structure of HSPGs through an increase in heparanase production [ 31 ]. This creates an environment where heparan-bound factors are released so that they can interact with macrophages and immune cells.…”

“…Other possibilities include the genetic modifications of pre-adipocytes and/or vascular cells to up- or down-regulate various genes that control the sulfation and syntheses the carbohydrate chains for HS. Sulfation of GAG chains is mediated by two families of genes: one family mediates the attachment of sulfates to chondroitin, dermatan, and keratan sulfates, while the second family mediates attachment to heparan sulfates [ 31 ]. Such studies would provide needed information to understand better the role of HSPGs in adipose tissue production of adipokines.…”

Modular Synthesis of Heparan Sulfate Oligosaccharides Having N-Acetyl and N-Sulfate Moieties

“…The methodology will make it possible to prepare panels of compounds for structure−activity relationship studies to better understand the biology of heparan sulfate. A recent paper demonstrated that trifluoromethylphenyl-methanimine can also be employed to make HS oligosaccharides to modulate heparanase activity, 61 which is an enzyme that can remodel HS and has been implicated in cancer. The microarray data highlight key requirements of chemokines to engage with HS.…”