Rapid macropinocytic transfer of α-synuclein to lysosomes
Armin Bayati, Emily Banks, Chanshuai Han, Wen Luo, Wolfgang Reintsch, Cornelia E. Zorca, Irina Shlaifer, Esther del Cid‐Pellitero, Benoît Vanderperre, Heidi M. McBride, Edward A. Fon, Thomas M. Durcan, Peter S. McPherson
Abstract
The nervous system spread of alpha-synuclein fibrils is thought to cause Parkinson's disease (PD) and other synucleinopathies; however, the mechanisms underlying internalization and cellular spread are enigmatic. Here, we use confocal and superresolution microscopy, subcellular fractionation, and electron microscopy (EM) of immunogold-labeled α-synuclein preformed fibrils (PFFs) to demonstrate that this form of the protein undergoes rapid internalization and is targeted directly to lysosomes in as little as 2 min. Uptake of PFFs is disrupted by macropinocytic inhibitors and circumvents classical endosomal pathways. Immunogold-labeled PFFs are seen at the highly curved inward edge of membrane ruffles, in newly formed macropinosomes, in multivesicular bodies and in lysosomes. While most fibrils remain in lysosomes, a portion is transferred to neighboring naive cells along with markers of exosomes. These data indicate that PFFs use a unique internalization mechanism as a component of cell-to-cell propagation.