Cooperative inhibition of SNARE-mediated vesicle fusion by \u03b1-synuclein monomers and oligomers

Gyeongji Yoo,Nam Ki Lee,Sanghun Yeou,Yeon-Kyun Shin,Jung Bae Son

doi:10.1038/s41598-021-90503-0

Abstract

The primary hallmark of Parkinson's disease (PD) is the generation of Lewy bodies of which major component is α-synuclein (α-Syn). Because of increasing evidence of the fundamental roles of α-Syn oligomers in disease progression, α-Syn oligomers have become potential targets for therapeutic interventions for PD. One of the potential toxicities of α-Syn oligomers is their inhibition of SNARE-mediated vesicle fusion by specifically interacting with vesicle-SNARE protein synaptobrevin-2 (Syb2), which hampers dopamine release. Here, we show that α-Syn monomers and oligomers cooperatively inhibit neuronal SNARE-mediated vesicle fusion. α-Syn monomers at submicromolar concentrations increase the fusion inhibition by α-Syn oligomers. This cooperative pathological effect stems from the synergically enhanced vesicle clustering. Based on this cooperative inhibition mechanism, we reverse the fusion inhibitory effect of α-Syn oligomers using small peptide fragments. The small peptide fragments, derivatives of α-Syn, block the binding of α-Syn oligomers to Syb2 and dramatically reverse the toxicity of α-Syn oligomers in vesicle fusion. Our findings demonstrate a new strategy for therapeutic intervention in PD and related diseases based on this specific interaction of α-Syn.

Highlights

The primary hallmark of Parkinson’s disease (PD) is the generation of Lewy bodies of which major component is α-synuclein (α-Syn)
This lipid mixing was monitored by the fluorescence resonance energy transfer (FRET) signal between 1,1′-dioctadecyl-3,3,3′,3′tetramethylindocarbocyanine perchlorate (DiI) and 1,1′-dioctadecyl3,3,3′,3′-tetramethylindodicarbocyanine perchlorate (DiD) dyes (Supplementary Fig. S1B). α-Syn oligomers were prepared by incubating the α-Syn monomer (15 μM) with dopamine (100 μM) at 37 °C for 72 h (Supplementary Fig. S2A) and purified using size exclusion chromatography (Supplementary Fig. S2B and C)[15,35,36,37]
We showed that the T44P/A89P α-Syn monomer blocks the clustering of v-vesicles induced by α-Syn oligomers, which results in restoration of SNARE-mediated vesicle fusion

Summary

Introduction

The primary hallmark of Parkinson’s disease (PD) is the generation of Lewy bodies of which major component is α-synuclein (α-Syn). Α-Syn monomers at submicromolar concentrations increase the fusion inhibition by α-Syn oligomers This cooperative pathological effect stems from the synergically enhanced vesicle clustering. Due to increasing evidence of the fundamental roles of α-Syn oligomers in disease progression, the oligomeric forms of α-Syn have emerged as one of the most compelling therapeutic targets for PD and related neurodegenerative disorders[15,17,18,19,20] It has been challenging, to develop effective strategies to suppress oligomerization of α-Syn and its associated toxicity because the assembly of the oligomers is dependent on multiple factors, including the concentration of the protein, oxidative stress, heavy metal, pH, and temperature in c ells[21,22,23,24]. In addition to an in vitro study, α-Syn oligomers generated by dopamine in vivo induce nigrostriatal degeneration and associated s ymptoms[18]

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Results

Conclusion