GLUCOSAMINE INHIBITS PLATELET AGGREGATION AND MODIFIES PROTEIN O-GlcNACYLATION

Blood platelets play important roles in haemostasis, thrombosis; wound healing, atherosclerosis, inflammation, immunity, and tumour metastasis. Glucosamine (GlcN) decreases platelet aggregation induced by adenosine diphosphate (ADP), this was demonstrated in human and animal platelets. The role of protein glycosylation as a mechanism to explain the anti-platelet effects of glucosamine is not clear. This study evaluated the effects of GlcN on ADP and thrombin-induced platelet aggregation, and changes on protein O-GlcNAcylation (O-GlcNAc). Thirty human samples from healthy donors analysed by flow cytometry, platelet aggregometry, immunofluorescence microscopy and western blot were used to evaluate the effects of GlcN on platelet function and protein O-GlcNAc. For assays, platelets were incubated or not with GlcN 20 mM. To evaluate the specificity of GlcN on platelet aggregation, platelets were incubated with N-acetylglucosamine (GlcNAc), galactose (Gal) and fucose (Fuc). GlcN inhibits both, ADP and thrombin-induced platelet aggregation in 65 % and 48 %, respectively. GlcNAc partially inhibited the effects of thrombin on platelet aggregation; Gal and Fuc did not have such effects. These effects could be attributed to changes on O-GlcNAc. GlcN did not show effects on the expression of the enzymes responsible of O-GlcNAc cycling. O-GlcNAc observed in platelet at basal conditions and showed a different pattern after GlcN incubation, suggesting that O-GlcNAc is cycling in platelets. This is the first study that shows a likely relationship between GlcN-induced inhibitory effects on platelet aggregation and O-GlcNAc.