α-Synuclein strains target distinct brain regions and cell types

Lau et al. find that alpha-synuclein strains initiate distinct diseases when injected into mice, which provides a potential molecular explanation for the clinical and pathological differences between Parkinson's disease and related neurodegenerative disorders. The clinical and pathological differences between synucleinopathies such as Parkinson's disease and multiple system atrophy have been postulated to stem from unique strains of alpha-synuclein aggregates, akin to what occurs in prion diseases. Here we demonstrate that inoculation of transgenic mice with different strains of recombinant or brain-derived alpha-synuclein aggregates produces clinically and pathologically distinct diseases. Strain-specific differences were observed in the signs of neurological illness, time to disease onset, morphology of cerebral alpha-synuclein deposits and the conformational properties of the induced aggregates. Moreover, different strains targeted distinct cellular populations and cell types within the brain, recapitulating the selective targeting observed among human synucleinopathies. Strain-specific clinical, pathological and biochemical differences were faithfully maintained after serial passaging, which implies that alpha-synuclein propagates via prion-like conformational templating. Thus, pathogenic alpha-synuclein exhibits key hallmarks of prion strains, which provides evidence that disease heterogeneity among the synucleinopathies is caused by distinct alpha-synuclein strains.