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Prion-like spreading of pathological ?-synuclein in brain.

ABSTRACT: ?-Synuclein is the major component of filamentous inclusions that constitute the defining characteristic of neurodegenerative ?-synucleinopathies. However, the molecular mechanisms underlying ?-synuclein accumulation and spread are unclear. Here we show that intracerebral injections of sarkosyl-insoluble ?-synuclein from brains of patients with dementia with Lewy bodies induced hyperphosphorylated ?-synuclein pathology in wild-type mice. Furthermore, injection of fibrils of recombinant human and mouse ?-synuclein efficiently induced similar ?-synuclein pathologies in wild-type mice. C57BL/6J mice injected with ?-synuclein fibrils developed abundant Lewy body/Lewy neurite-like pathology, whereas mice injected with soluble ?-synuclein did not. Immunoblot analysis demonstrated that endogenous mouse ?-synuclein started to accumulate 3 months after inoculation, while injected human ?-synuclein fibrils disappeared in about a week. These results indicate that ?-synuclein fibrils have prion-like properties and inoculation into wild-type brain induces ?-synuclein pathology in vivo. This is a new mouse model of sporadic ?-synucleinopathy and should be useful for elucidating progression mechanisms and evaluating disease-modifying therapy.

SUBMITTER: Masuda-Suzukake M

PROVIDER: S-EPMC3613715 | biostudies-literature | 2013 Apr

REPOSITORIES: biostudies-literature

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Prion-like spreading of pathological α-synuclein in brain.

Masuda-Suzukake Masami M Nonaka Takashi T Hosokawa Masato M Oikawa Takayuki T Arai Tetsuaki T Akiyama Haruhiko H Mann David M A DM Hasegawa Masato M

Brain : a journal of neurology 20130306 Pt 4

α-Synuclein is the major component of filamentous inclusions that constitute the defining characteristic of neurodegenerative α-synucleinopathies. However, the molecular mechanisms underlying α-synuclein accumulation and spread are unclear. Here we show that intracerebral injections of sarkosyl-insoluble α-synuclein from brains of patients with dementia with Lewy bodies induced hyperphosphorylated α-synuclein pathology in wild-type mice. Furthermore, injection of fibrils of recombinant human and ...[more]

PMID: 23466394

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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.

Project description:BackgroundLeucine rich repeat kinase 2 (LRRK2) and SNCA are genetically linked to late-onset Parkinson's disease (PD). Aggregated α-synuclein pathologically defines PD. Recent studies identified elevated LRRK2 expression in pro-inflammatory CD16+ monocytes in idiopathic PD, as well as increased phosphorylation of the LRRK2 kinase substrate Rab10 in monocytes in some LRRK2 mutation carriers. Brain-engrafting pro-inflammatory monocytes have been implicated in dopaminergic neurodegeneration in PD models. Here we examine how α-synuclein and LRRK2 interact in monocytes and subsequent neuroinflammatory responses.MethodsHuman and mouse monocytes were differentiated to distinct transcriptional states resembling macrophages, dendritic cells, or microglia, and exposed to well-characterized human or mouse α-synuclein fibrils. LRRK2 expression and LRRK2-dependent Rab10 phosphorylation were measured with monoclonal antibodies, and myeloid cell responses to α-synuclein fibrils in R1441C-Lrrk2 knock-in mice or G2019S-Lrrk2 BAC mice were evaluated by flow cytometry. Chemotaxis assays were performed with monocyte-derived macrophages stimulated with α-synuclein fibrils and microglia in Boyden chambers.Resultsα-synuclein fibrils robustly stimulate LRRK2 and Rab10 phosphorylation in human and mouse macrophages and dendritic-like cells. In these cells, α-synuclein fibrils stimulate LRRK2 through JAK-STAT activation and intrinsic LRRK2 kinase activity in a feed-forward pathway that upregulates phosphorylated Rab10. In contrast, LRRK2 expression and Rab10 phosphorylation are both suppressed in microglia-like cells that are otherwise highly responsive to α-synuclein fibrils. Corroborating these results, LRRK2 expression in the brain parenchyma occurs in pro-inflammatory monocytes infiltrating from the periphery, distinct from brain-resident microglia. Mice expressing pathogenic LRRK2 mutations G2019S or R1441C have increased numbers of infiltrating pro-inflammatory monocytes in acute response to α-synuclein fibrils. In primary cultured macrophages, LRRK2 kinase inhibition dampens α-synuclein fibril and microglia-stimulated chemotaxis.ConclusionsPathologic α-synuclein activates LRRK2 expression and kinase activity in monocytes and induces their recruitment to the brain. These results predict that LRRK2 kinase inhibition may attenuate damaging pro-inflammatory monocyte responses in the brain.

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Prion-like spreading of pathological ?-synuclein in brain.

Publications

Prion-like spreading of pathological α-synuclein in brain.

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