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Viral alpha-synuclein knockdown prevents spreading synucleinopathy

ABSTRACT: Abstract The accumulation of aggregated alpha-synuclein (α-syn) in Parkinson's disease, dementia with Lewy bodies and multiple system atrophy is thought to involve a common prion-like mechanism, whereby misfolded α-syn provides a conformational template for further accumulation of pathological α-syn. We tested whether silencing α-syn gene expression could reduce native non-aggregated α-syn substrate and thereby disrupt the propagation of pathological α-syn initiated by seeding with synucleinopathy-affected mouse brain homogenates. Unilateral intracerebral injections of adeno-associated virus serotype-1 encoding microRNA targeting the α-syn gene reduced the extent and severity of both the α-syn pathology and motor deficits. Importantly, a moderate 50% reduction in α-syn was sufficient to prevent the spread of α-syn pathology to distal brain regions. Our study combines behavioural, immunohistochemical and biochemical data that strongly support α-syn knockdown gene therapy for synucleinopathies. Menon et al. report that AAV1-mediated expression of microRNA targeting alpha-synuclein gene expression reduced both motor deficits and pathology in mice that were initiated by an injection of synucleinopathy-affected brain homogenates. Partial suppression of alpha-synuclein was sufficient to prevent pathology spreading into distal brain regions with normal alpha-synuclein levels. Graphical Abstract Graphical Abstract

SUBMITTER: Menon S

PROVIDER: S-EPMC8576194 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundThe accumulation of misfolded proteins appears as a fundamental pathogenic process in human neurodegenerative diseases. In the case of synucleinopathies such as Parkinson's disease (PD) or dementia with Lewy bodies (DLB), the intraneuronal deposition of aggregated alpha-synuclein (?S) is a major characteristic of the disease, but the molecular basis distinguishing the disease-associated protein (?SD) from its normal counterpart remains poorly understood. However, recent research suggests that a prion-like mechanism could be involved in the inter-cellular and inter-molecular propagation of aggregation of the protein within the nervous system.ResultsOur data confirm our previous observations of disease acceleration in a transgenic mouse line (M83) overexpressing a mutated (A53T) form of human ?S, following inoculation of either brain extracts from sick M83 mice or fibrillar recombinant ?S. A similar phenomenon is observed following a "second passage" in the M83 mouse model, including after stereotactic inoculations into the hippocampus or cerebellum. For further molecular analyses of ?SD, we designed an ELISA test that identifies ?SD specifically in sick mice and in the brain regions targeted by the pathological process in this mouse model. ?SD distribution, mainly in the caudal brain regions and spinal cord, overall appears remarkably uniform, whatever the conditions of experimental challenge. In addition to specific detection of ?SD immunoreactivity using an antibody against Ser129 phosphorylated ?S, similar results were observed in ELISA with several other antibodies against the C-terminal part of ?S, including an antibody against non phosphorylated ?S. This also indicated consistent immunoreactivity of the murine ?S protein specifically in the affected brain regions of sick mice.ConclusionsPrion-like behaviour in propagation of the disease-associated ?S was confirmed with the M83 transgenic mouse model, that could be followed by an ELISA test. The ELISA data question their possible relationship with the conformational differences between the disease-associated ?S and its normal counterpart.

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Viral alpha-synuclein knockdown prevents spreading synucleinopathy

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