alpha-Synuclein propagates from mouse brain to grafted dopaminergic neurons and seeds aggregation in cultured human cells

• Post-mortem analyses of brains from patients with Parkinson disease who received fetal mesencephalic transplants show that alpha-synuclein-containing (alpha-syn-containing) Lewy bodies gradually appear in grafted neurons. Here, we explored whether intercellular transfer of alpha-syn from host to graft, followed by seeding of alpha-syn aggregation in recipient neurons, can contribute to this phenomenon. We assessed alpha-syn cell-to-cell transfer using microscopy, flow cytometry, and high-content screening in several coculture model systems. Coculturing cells engineered to express either GFP- or DsRed-tagged alpha-syn resulted in a gradual increase in double-labeled cells. Importantly, alpha-syn-GFP derived from 1 neuroblastoma cell line localized to red fluorescent aggregates in other cells expressing DsRed-alpha-syn, suggesting a seeding effect of transmitted alpha-syn. Extracellular alpha-syn was taken up by cells through endocytosis and interacted with intracellular alpha-syn. Next, following intracortical injection of recombinant alpha-syn in rats, we found neuronal uptake was attenuated by coinjection of an endocytosis inhibitor. Finally, we demonstrated in vivo transfer of alpha-syn between host cells and grafted dopaminergic neurons in mice overexpressing human alpha-syn. In summary, intercellularly transferred alpha-syn interacts with cytoplasmic alpha-syn and can propagate alpha-syn pathology. These results suggest that alpha-syn propagation is a key element in the progression of Parkinson disease pathology.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Neurovetenskaper (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Neurosciences (hsv//eng)

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