Abstract
BackgroundGenetic studies have established a causative role for α-synuclein (αS) in Parkinson’s disease (PD), and the presence of αS aggregates in the form of Lewy body (LB) and Lewy neurite (LN) protein inclusions are defining pathological features of PD. Recent data has established that extracellular αS aggregates can induce intracellular αS pathologies supporting the hypothesis that αS pathology can spread via a “prion-like” self-templating mechanism.ResultsHere we investigated the potential for conformational templating of αS intracellular aggregates by seeding using recombinant wild-type and PD-linked mutant (A53T and E46K) αS in primary mixed neuronal-glial cultures. We find that wild-type and A53T αS fibrils predominantly seed flame-like inclusions in both neurons and astrocytes of mixed primary cultures; whereas the structurally distinct E46K fibrils seed punctate, rounded inclusions. Notably, these differences in seeded inclusion formation in these cultures reflect differences in inclusion pathology seen in transgenic mice expressing the A53T or E46K αS mutants. We further show that the inclusion morphology is dictated primarily by the seed applied rather than the form of αS expressed. We also provide initial evidence that αS inclusion pathology can be passaged in primary astrocyte cultures.ConclusionThese studies establish for the first time that αS aggregation in cultured cells can occur by a morphological self-templating mechanism.
Highlights
Genetic studies have established a causative role for α-synuclein in Parkinson’s disease (PD), and the presence of αS aggregates in the form of Lewy body (LB) and Lewy neurite (LN) protein inclusions are defining pathological features of PD
Recent postmortem studies in PD patients suggest that the spread of pathology can occur intercellularly [22,23,24,25,26], and the induction of αS pathology in experimental mouse models using intracerebral injection of recombinant αS fibrils suggests that amyloidogenic αS may spread by a “prion-like” mechanism [27,28]
To determine if we could induce inclusion formation in primary mixed mouse neuronal-glial cultures, we tested whether overexpression of wild-type human αS mediated by rAAV2/1 vectors and addition of amino-terminally truncated exogenous recombinant wild-type (21–140) αS fibrils was sufficient to induce αS aggregate formation
Summary
Genetic studies have established a causative role for α-synuclein (αS) in Parkinson’s disease (PD), and the presence of αS aggregates in the form of Lewy body (LB) and Lewy neurite (LN) protein inclusions are defining pathological features of PD. Recent postmortem studies in PD patients suggest that the spread of pathology can occur intercellularly [22,23,24,25,26], and the induction of αS pathology in experimental mouse models using intracerebral injection of recombinant αS fibrils suggests that amyloidogenic αS may spread by a “prion-like” mechanism [27,28]. A major difference between “prionlike” transmission and classical prion disease is paucity of inter-organism transmission For many amyloids this “prion-like” conversion of protein conformation can often have unique structural and morphological properties that can be transmitted and this phenomenon has been termed “strain-specific” [29,30]
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