Thioglycosides Are Efficient Metabolic Decoys of Glycosylation that Reduce Selectin Dependent Leukocyte Adhesion

Abstract

SUMMARY Metabolic decoys are synthetic analogs of naturally occurring biosynthetic acceptors. These compounds divert cellular biosynthetic pathways by acting as artificial substrates that usurp the activity of natural enzymes. While O-linked glycosides are common, they are only partially effective even at millimolar concentrations. In contrast, we report that N-acetylglucosamine (GlcNAc) incorporated into various thioglycosides robustly truncate cell-surface N- and O-linked glycan biosynthesis at 10–100μM concentrations. The >10 fold greater inhibition is in part due to the resistance of thioglycosides to hydrolysis by intracellular hexosaminidases. The thioglycosides reduce β-galactose incorporation into lactosamine chains, cell-surface sialyl Lewis-X expression, and leukocyte rolling on selectin-substrates including inflamed endothelial cells under fluid shear. Treatment of granulocytes with thioglycosides prior to murine infusion inhibited neutrophil homing to sites of acute inflammation and bone marrow by ~80–90%. Overall, thioglycosides represent an easy to synthesize class of efficient metabolic inhibitors/decoys. They reduce N-/O-linked glycan biosynthesis and inflammatory leukocyte accumulation.

Metabolic inhibitors of bacterial glycan biosynthesis

“…The progress that has been made in this area has relied on indepth characterization of glycosyltransferases, [75][76][77][78] information that is oen a rate-limiting step in inhibitor development. As an alternative to direct screening of glycosyltransferases, Vocadlo, 42 Paulson 44 and others 21,45 have demonstrated the potential of unnatural monosaccharides or glycosides bearing key structural features (e.g. O-benzyl glycosides, uorinated analogues) that act as global metabolic inhibitors of glycosylation within mammalian cells.…”

“…Molecular-level information concerning how glycan structure changes in the presence of metabolic inhibitors will be critical to gain incisive information on the structure-function relationship. Recent reports by Paulson and coworkers 44 and Wang et al, 45 for example, indicate successful strategies for characterizing the effects of metabolic inhibitors on cellular glycosylation in mammalian systems that should translate to bacterial systems. Moreover, molecular-level evidence will reveal the mechanism by which these analogues inhibit bacterial glycosylation.…”

“…Motivated by the successful development of small molecule inhibitors of glycosyltransferases in mammalian systems, [42][43][44][45] two classes of metabolic inhibitors were explored. The rst class of inhibitors was inspired by Esko's seminal work with metabolic substrate decoys such as benzyl-a-GalNAc (Bn-Gal-NAc).…”

“…The rst class of inhibitors was inspired by Esko's seminal work with metabolic substrate decoys such as benzyl-a-GalNAc (Bn-Gal-NAc). [45][46][47][48] Metabolic substrate decoys are small molecule analogues of endogenous glycoproteins that are recognized as acceptor substrates by glycosyltransferases, ultimately diverting glycan synthesis onto decoy substrates and leading to the synthesis of truncated glycans on proteins. Successful decoys in mammalian systems led us to design benzyl glycosides of Bac, DATDG, and FucNAc as substrate decoys of bacterial glycosyltransferases ( Fig.…”

Don’t sugarcoat it: How glycocalyx composition influences cancer progression

“…The drawback to these inhibitors is that most have minimal incorporation into cells at relatively high millimolar concentrations, which limits their therapeutic potential in the clinic (Kudelka et al, 2016). Some newly described glycosylation mimetics such as thioglycosides (Wang et al, 2018) may be able to overcome the hurdle of how to get high incorporation at lower concentrations.…”