Differential processing and secretion of A beta peptides and sAPP alpha in human platelets is regulated by thrombin and prostaglandine 2

Abstract

Metabolic and functional studies of the amyloid precursor protein (APP) in platelets have advanced our understanding of Alzheimer's disease (AD). Here we report that human platelets contain A beta peptides, process and secrete them constitutively. Platelets generate formerly unkown A beta-species by differential processing of APP. Release of A beta peptides were also increased by platelet activation with thrombin, indicating the existence of a regulated exocytotic pathway. We showed that A beta-levels, A beta-processing patterns and A beta-release kinetics were regulated by thrombin. In controls, release of A beta peptide species (A beta 1-40/42 and 1-37/38/39/) continued for more than 4 h, while thrombin activated cells ceased secretion after 1 h at large. Treatment of platelets with prostaglandine 2 slowed this process down. Intracellular A beta peptide concentrations decreased steadily until no peptides could be detected after 20 h (control) or after 4 h (thrombin) in cultured platelets. (C) 2008 Elsevier Inc. All rights reserved.