Glycomics analysis of resting and activated human platelets (789.1)

Abstract

Cardiovascular diseases are the most common causes of death in developed countries and their prevalence rate is rapidly growing in developing countries. Genome‐wide association studies (GWAS) have identified associations between ABO blood group status and HLBS (heart, lung, blood, and sleep) disorders. ABO glycans are expressed on glycoproteins and glycosphingolipids (GSLs) of cells and tissues relevant to HLBS disorders,including endothelial cells and platelets. Several major HLBS disorders, particularly acute myocardial infarction and acute lung injury, are characterized by endothelium dysfunction and platelet‐driven thrombosis. Therefore, a comprehensive understanding of the disposition of ABO glycan expression by endothelial cells and platelets is essential for elucidating the mechanisms by which these glycans influence risk for cardiovascular disease. Toward this end, we have undertaken the structural characterization of GSL, and N‐ and O‐linked glycoprotein glycans in resting and activated platelets. The preparations of GSLs are permethylated and analyzed by direct infusion into an NSI‐LTQ/Orbitrap mass spectrometer. N‐ glycans are enzymatically released and O‐glycans are released by reductive beta‐elimination from glycoprotein preparations prior to permethylation and subsequent quantitative analysis by mass spectrometry. For GSLs, expression levels of lactosylceramide (LacCer) and of the sialylated form of LacCer, ganglioside GM3, were significantly decreased and increased, respectively, upon activation. For N‐glycans, high‐mannose structures and mono‐ and disialylated N‐glycans were significantly increased in activated platelets compared to resting platelets. These results are consistent with a systemic upregulation in human platelet glycoconjugate sialylation during activation of platelets and enhanced glycan‐mediated platelet adhesion and thrombosis.Grant Funding Source: NIH