Authors
Yihong Ye, Kamal Kumar, Yue Xu, Fenfen Xu, Susan Ferro-Novick
Published in
Molecular biology of the cell. Pages mbcE26030138. Jul 15, 2026. Epub Jul 15, 2026.
Abstract
The misfolding and aggregation of α-synuclein (α-syn), an abundant synaptic protein, leads to the pathogenesis of Parkinson's disease and related synucleinopathies. The cell-to-cell propagation of seeding-competent α-syn is initiated by unconventional protein secretion, yet the physiological pathway(s) underlying this process remain poorly defined. Here we show that α-syn secretion in human cells is mediated by Reticulon-3L (RTN3L)-dependent endoplasmic reticulum autophagy (ER-phagy), a conserved protein quality-control pathway that safeguards ER protein homeostasis. We also demonstrate that RTN3L cooperates with several autophagy regulators, including the ULK1 cofactor FIP200, to drive the delivery of α-syn into an acidic endolysosomal compartment. Increasing concentrations of α-syn disrupt ER-lysosome traffic and α-syn-containing vesicles appear to be rerouted to the cell surface. Consistent with this proposal, knockdown of vesicle associated SNAREs, that mediate fusion at the cell surface, disrupt α-syn secretion. These findings suggest that pathogenic α-syn secretion arises as a by-product of a physiological clearance mechanism, driven by the fusion of autophagosome-derived vesicles with the plasma membrane. Our results provide a conceptual framework for understanding how an intracellular proteostasis pathway, when mis-regulated, could contribute to the spread of neurodegenerative pathology.
PMID:
42455619
Bibliographic data and abstract were imported from PubMed on 15 Jul 2026.
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