Platelet α- and γ-synucleins in Parkinson's disease and normal control subjects

alpha-Synuclein (alpha SN) has been implicated in Parkinson's Disease (PD) and alpha SN is a major component of Lewy bodies (LBs). This study explored platelets as a model system for study of alpha SN metabolism and platelet alpha SN as a diagnostic marker for PD. We used Western blot analysis to characterize and compare platelet and brain alpha-, beta- and gamma SN; and to quantitate alpha SN levels in platelets from PD and age-matched controls. We found that platelets contain full-length alpha SN and 6 and 12 kDa fragments, and gamma SN-like protein. alpha SN and gamma SN were not secreted by thrombin-activated platelets. Furthermore, we also found that the alpha SN and gamma SN levels in sporadic PD patients and age-matched normal controls were not significantly different. This indicates that platelet alpha SN or gamma SN is not a suitable peripheral diagnostic marker for PD. Platelets may be used for study of alpha SN and gamma SN metabolism, and may give some broad insight into the normal functions of alpha SN and gamma SN.