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Acta Neuropathol. 2018 Oct;136(4):621-639. doi: 10.1007/s00401-018-1892-1. Epub 2018 Jul 25.

Synapsin III deficiency hampers α-synuclein aggregation, striatal synaptic damage and nigral cell loss in an AAV-based mouse model of Parkinson's disease.

Author information

1
Division of Pharmacology, Department of molecular and Translational Medicine, University of Brescia, Viale Europa no. 11, 25123, Brescia, Italy.
2
Department of Biology, University of Padova, Via Ugo Bassi 58b, 35121, Padua, Italy.
3
Center for Synaptic Neuroscience and Technology, Italian Institute of Technology, Via Morego, 30, 16163, Genoa, Italy.
4
IRCCS Ospedale Policlinico San Martino, Largo R. Benzi 10, 16132, Genoa, Italy.
5
Neurobiology Unit, BMC A11, Department of Experimental Medical Science, Lund University, 221 84, Lund, Sweden.
6
Division of Pharmacology, Department of molecular and Translational Medicine, University of Brescia, Viale Europa no. 11, 25123, Brescia, Italy. arianna.bellucci@unibs.it.
7
Laboratory for Preventive and Personalized Medicine, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy. arianna.bellucci@unibs.it.

Abstract

Parkinson's disease (PD), the most common neurodegenerative movement disorder, is characterized by the progressive loss of nigral dopamine neurons. The deposition of fibrillary aggregated α-synuclein in Lewy bodies (LB), that is considered to play a causative role in the disease, constitutes another key neuropathological hallmark of PD. We have recently described that synapsin III (Syn III), a synaptic phosphoprotein that regulates dopamine release in cooperation with α-synuclein, is present in the α-synuclein insoluble fibrils composing the LB of patients affected by PD. Moreover, we observed that silencing of Syn III gene could prevent α-synuclein fibrillary aggregation in vitro. This evidence suggests that Syn III might be crucially involved in α-synuclein pathological deposition. To test this hypothesis, we studied whether mice knock-out (ko) for Syn III might be protected from α-synuclein aggregation and nigrostriatal neuron degeneration resulting from the unilateral injection of adeno-associated viral vectors (AAV)-mediating human wild-type (wt) α-synuclein overexpression (AAV-hαsyn). We found that Syn III ko mice injected with AAV-hαsyn did not develop fibrillary insoluble α-synuclein aggregates, showed reduced amount of α-synuclein oligomers detected by in situ proximity ligation assay (PLA) and lower levels of Ser129-phosphorylated α-synuclein. Moreover, the nigrostriatal neurons of Syn III ko mice were protected from both synaptic damage and degeneration triggered by the AAV-hαsyn injection. Our observations indicate that Syn III constitutes a crucial mediator of α-synuclein aggregation and toxicity and identify Syn III as a novel therapeutic target for PD.

KEYWORDS:

AAV; Nigrostriatal degeneration; Syn III; Synaptic proteins alterations; α-Synuclein aggregation

PMID:
30046897
DOI:
10.1007/s00401-018-1892-1

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