αB-crystallin extracellularly suppresses ADP-induced granule secretion from human platelets

Abstract 

αB-crystallin, a low-molecular-weight heat shock protein (HSP), has binding sites on platelets. However, the exact role of αB-crystallin is not clarified. In this study, we investigated the effect of αB-crystallin on platelet granule secretion. αB-crystallin attenuated the adenosine diphosphate (ADP)-induced phosphorylation of p44/p42 mitogen-activated protein kinase (MAPK) and p38 MAPK. The ADP-stimulated HSP27 phosphorylation was markedly reduced by αB-crystallin. αB-crystallin significantly suppressed the ADP-induced secretions of both platelet-derived growth factor (PDGF)-AB and serotonin. Therefore, our results strongly suggest that αB-crystallin extracellularly suppresses platelet granule secretion by inhibition of HSP27 phosphorylation via p44/p42 MAPK and p38 MAPK.

Abbreviations: HSP, heat shock protein, ADP, adenosine diphosphate, MAPK, mitogen-activated protein kinase, PDGF, platelet-derived growth factor, 5-HT, serotonin, PRP, platelet rich plasma, ELISA, enzyme-linked immunosorbent assay, SDS, sodium dodecyl sulfate, PAGE, SDS–polyacrylamide gel electrophoresis

Keywords: Heat shock protein, αB-crystallin, Platelet, Adenosine diphosphate, Platelet-derived growth factor-AB, Serotonin