Discovery illuminates how Parkinson’s disease spreads in the brain

Good news!

"Aggregates of the protein alpha-synuclein spread in the brains of people with Parkinson’s disease through a cellular waste-ejection process, suggests a new study led by Weill Cornell Medicine researchers.
During the process, called lysosomal exocytosis, neurons eject protein waste they cannot break down and recycle. The discovery ... could resolve one of the mysteries of Parkinson’s disease and lead to new strategies for treating or preventing the neurological disorder. ..."

From the abstract:

"Considerable evidence supports the release of pathogenic aggregates of the neuronal protein α-Synuclein (αSyn) into the extracellular space. While this release is proposed to instigate the neuron-to-neuron transmission and spread of αSyn pathology in synucleinopathies including Parkinson’s disease, the molecular-cellular mechanism(s) remain unclear. To study this, we generated a new mouse model to specifically immunoisolate neuronal lysosomes, and established a long-term culture model where αSyn aggregates are produced within neurons without the addition of exogenous fibrils. We show that neuronally generated pathogenic species of αSyn accumulate within neuronal lysosomes in mouse brains and primary neurons. We then find that neurons release these pathogenic αSyn species via SNARE-dependent lysosomal exocytosis. The released aggregates are non-membrane enveloped and seeding-competent. Additionally, we find that this release is dependent on neuronal activity and cytosolic Ca2+. These results propose lysosomal exocytosis as a central mechanism for the release of aggregated and degradation-resistant proteins from neurons."

Discovery illuminates how Parkinson’s disease spreads in the brain | Cornell Chronicle

Lysosomal exocytosis releases pathogenic α-synuclein species from neurons in synucleinopathy models (open access)

Fig. 3. Pathogenic αSyn species accumulate within neuronal lysosomes in mouse brains and primary neurons.