Heterogeneity in platelet secretion

Abstract

Platelets, especially their α‐granules, are repositories for many cytokines and growth factors and thus, have profound roles in thrombosis, inflammation, atherosclerosis, and angiogenesis .Our work seeks to determine if these platelet cargo molecules are released with differential kinetics and/or in response to different agonists. Our experiments use antibody arrays to quantify the release of ~20 different proteins. In the initial stages of our analysis, thrombin has been used as agonist (activation through PAR receptors) and platelets have been stimulated for increasing times. We have detected two different classes of secretion from α‐granules that could be categorized as slow and rapid secretion events. These kinetic studies of secretion from α‐granules are being done in conjunction with dense core granule and lysosomal granule release and the pattern followed by the α‐granules is intermediate, with densecore granule release being very rapid and lysosomal granule release being much slower. Similar kinetics could be seen when they were stimulated with Convulxin (activation through GPVI pathway) and PAR1 activation peptide. Future experiments will determine if other agonists alter the pattern and/or kinetics of platelet cargo release. This work is supported by NIH grants (HL56652 and HL091893) to S.W.W.