British Journal of Pharmacology vol:166 issue:3 pages:1097-1113
Background and purpose The aggregation of α-synuclein (α-syn) is connected to the pathology of Parkinson's disease. Recently, it was shown that prolyl oligopeptidase (PREP) accelerates the aggregation of α-syn in vitro. The aim of this study was to investigate the effects of a PREP inhibitor, KYP-2047, on α-syn aggregation in cell lines overexpressing wild-type or A30P/A53T mutant human α-syn, and in the brains of two A30P α-syn transgenic mouse strains. Experimental approach Cells were exposed to oxidative stress, and then incubated with the PREP inhibitor during or after the stress. Wild-type or transgenic mice were treated for 5 days with KYP-2047 (2x3 mg/kg a day). Besides immunohistochemistry and thioflavin S staining, soluble and insoluble α-syn protein levels were measured by Western blot. α-syn mRNA levels were quantified by PCR. The colocalization of PREP and α-syn, and the effect of KYP-2047 on cell viability were also investigated. Key results In cell lines, oxidative stress induced a robust aggregation of α-syn, and low concentrations of KYP-2047 significantly reduced the number of cells with α-syn inclusions while abolishing the colocalization of α-syn and PREP. KYP-2047 significantly reduced the amount of aggregated α-syn, and it had beneficial effects on cell viability. In the transgenic mice, a 5-day treatment with the PREP inhibitor reduced the amount of α-syn immunoreactivity and soluble α-syn protein in the brain. Conclusions and implications The results suggest that the PREP may play a role in brain accumulation and aggregation of α-syn, while KYP-2047 seems to effectively prevent these processes.