Inhibition of alpha-synuclein aggregation by multifunctional dopamine agonists assessed by a novel in vitro assay and an in vivo Drosophila synucleinopathy model.

Deepthi Yedlapudi,Aloke K Dutta,Dan Luo,Sokol V Todi,Gnanada S Joshi

doi:10.1038/srep38510

Abstract

Aggregation of alpha synuclein (α-syn) leading to dopaminergic neuronal death has been recognized as one of the main pathogenic factors in the initiation and progression of Parkinson’s disease (PD). Consequently, α-syn has been targeted for the development of therapeutics for PD. We have developed a novel assay to screen compounds with α-syn modulating properties by mimicking recent findings from in vivo animal studies involving intrastriatal administration of pre-formed fibrils in mice, resulting in increased α-syn pathology accompanying the formation of Lewy-body (LB) type inclusions. We found that in vitro generated α-syn pre-formed fibrils induce seeding of α-syn monomers to produce aggregates in a dose-and time-dependent manner under static conditions in vitro. These aggregates were toxic towards rat pheochromocytoma cells (PC12). Our novel multifunctional dopamine agonists D-519 and D-520 exhibited significant neuroprotection in this assay, while their parent molecules did not. The neuroprotective properties of our compounds were further evaluated in a Drosophila model of synucleinopathy. Both of our compounds showed protective properties in fly eyes against the toxicity caused by α-syn. Thus, our in vitro results on modulation of aggregation and toxicity of α-syn by our novel assay were further validated with the in vivo experiments.

Highlights

We show here that multifunctional dopamine agonists, D-519 and D-520 (Fig. 1A), developed by us are capable of inhibiting α-syn aggregate formation, which resulted in reduction of toxicity
Discussion α-Syn aggregates have been found in healthy grafted neurons in Parkinson’s disease (PD) patients and endogenous α-syn has been shown to be recruited into fibrillar aggregates through a seeding mechanism in transgenic mice[24,50]
In order to mimic the conditions occurring in the PD brain, here, we have developed a novel in vitro assay for the screening of small molecules which inhibit α-syn aggregation

Summary

Introduction

These include the use of anions[28], polyanions[29,30], polycations[31], salts[28], pesticides and herbicides[32,33,34], heavy metals[35], negatively charged detergents[36], molecular crowding[37,38,39], low pH40 and acidic phospholipids[41,42] Apart from these factors, agitation has been shown to induce aggregation and several assays have been developed based on this property to screen α-syn aggregation inhibitors[43].

Methods

Results

Conclusion