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Ann Neurol. 2013 Jul;74(1):109-18. doi: 10.1002/ana.23905. Epub 2013 Aug 6.

β-synuclein aggregates and induces neurodegeneration in dopaminergic neurons.

Author information

1
Department of Neurology, Center for Nanoscale Microscopy and Molecular Physiology of the Brain at University Medical Center Göttingen, Göttingen, Germany.

Abstract

OBJECTIVE:

Whereas the contribution of α-synuclein to neurodegeneration in Parkinson disease is well accepted, the putative impact of its close homologue, β-synuclein, is enigmatic. β-Synuclein is widely expressed throughout the central nervous system, as is α-synuclein, but the physiological functions of both proteins remain unknown. Recent findings have supported the view that β-synuclein can act as an ameliorating regulator of α-synuclein-induced neurotoxicity, having neuroprotective rather than neurodegenerative capabilities, and being nonaggregating due to the absence of most of the aggregation-promoting NAC domain. However, a mutation of β-synuclein linked to dementia with Lewy bodies rendered the protein neurotoxic in transgenic mice, and fibrillation of β-synuclein has been demonstrated in vitro.

METHODS:

Neurotoxicity and aggregation properties of α-, β-, and γ-synuclein were comparatively elucidated in the rat nigro-striatal projection and in cultured neurons.

RESULTS:

Supporting the hypothesis that β-synuclein can act as a neurodegeneration-inducing factor, we demonstrated that wild-type β-synuclein is neurotoxic for cultured primary neurons. Furthermore, β-synuclein formed proteinase K-resistant aggregates in dopaminergic neurons in vivo, leading to pronounced and progressive neurodegeneration in rats. Expression of β-synuclein caused mitochondrial fragmentation, but this fragmentation did not render mitochondria nonfunctional in terms of ion handling and respiration even at late stages of neurodegeneration. A comparison of the neurodegenerative effects induced by α-, β-, and γ-synuclein revealed that β-synuclein was eventually as neurotoxic as α-synuclein for nigral dopaminergic neurons, whereas γ-synuclein proved to be nontoxic and had very low aggregation propensity.

INTERPRETATION:

Our results suggest that the role of β-synuclein as a putative modulator of neuropathology in aggregopathies like Parkinson disease and dementia with Lewy bodies needs to be revisited.

PMID:
23536356
DOI:
10.1002/ana.23905
[Indexed for MEDLINE]

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