Abstract
Growing evidence emphasizes insufficient clearance of pathological alpha-synuclein (αSYN) aggregates in the progression of Parkinson’s disease (PD). Consequently, cellular degradation pathways represent a potential therapeutic target. Prolyl oligopeptidase (PREP) is highly expressed in the brain and has been suggested to increase αSYN aggregation and negatively regulate the autophagy pathway. Inhibition of PREP with a small molecule inhibitor, KYP-2407, stimulates autophagy and reduces the oligomeric species of αSYN aggregates in PD mouse models. However, whether PREP inhibition has any effects on intracellular αSYN fibrils has not been studied before. In this study, the effect of KYP2407 on αSYN preformed fibrils (PFFs) was tested in SH-SY5Y cells and human astrocytes. Immunostaining analysis revealed that both cell types accumulated αSYN PFFs intracellularly but KYP-2047 decreased intracellular αSYN deposits only in SH-SY5Y cells, as astrocytes did not show any PREP activity. Western blot analysis confirmed the reduction of high molecular weight αSYN species in SH-SY5Y cell lysates, and secretion of αSYN from SH-SY5Y cells also decreased in the presence of KYP-2407. Accumulation of αSYN inside the SH-SY5Y cells resulted in an increase of the auto-lysosomal proteins p62 and LC3BII, as well as calpain 1 and 2, which have been shown to be associated with PD pathology. Notably, treatment with KYP-2407 significantly reduced p62 and LC3BII levels, indicating an increased autophagic flux, and calpain 1 and 2 levels returned to normal in the presence of KYP-2407. Our findings indicate that PREP inhibition can potentially be used as therapy to reduce the insoluble intracellular αSYN aggregates.
Highlights
As one of the most common neurodegenerative disorders, Parkin son’s disease (PD) affects almost six million people worldwide, with age as the major risk factor [1]
The histopathological feature of PD is the presence of intra-neuronal in clusions called Lewy bodies and Lewy neurites that are mainly comprised of fibrillary alpha-synuclein [2,3]
There fore, we studied if Prolyl oligopeptidase (PREP) inhibition increased lysosomal degradation in the presence of αSYN preformed fibrils (PFF)
Summary
As one of the most common neurodegenerative disorders, Parkin son’s disease (PD) affects almost six million people worldwide, with age as the major risk factor [1]. The suggested mechanisms for this propagation are: release of αSYN aggregates from dying neurons to the surroundings, cell-to-cell contact, and secretion Reactive gliosis is another hallmark of PD where the glial cells of the brain enter an inflammatory state. Accumulating evidence emphasizes that direct interaction of αSYN with certain proteins [13,14], oxidative stress [15,16] as well as impaired degradation pathways [17,18] can initiate αSYN aggregation. Previous studies have shown that direct interaction between PREP and αSYN increases the aggregation propensities of αSYN [14,22, 23]. PREP inhibition was shown to reduce the levels of αSYN aggregates, soluble oligomers, in the brains of different PD mouse models and improve the motor symptoms [26,38, 39]. These data imply that KYP-2407 prevents αSYN accumulation and further aggregation in neuron-like cells
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
