Monitoring α-synuclein ubiquitination dynamics reveals key endosomal effectors mediating its trafficking and degradation.

Zenko D., Marsh J., Castle AR., Lewin R., Fischer R., Tofaris GK.

While defective α-synuclein homeostasis is central to Parkinson's pathogenesis, fundamental questions about its degradation remain unresolved. We have developed a bimolecular fluorescence complementation assay in living cells to monitor de novo ubiquitination of α-synuclein and identified lysine residues 45, 58, and 60 as critical ubiquitination sites for its degradation. This is mediated by NBR1 binding and entry into endosomes in a process that involves ESCRT I-III for subsequent lysosomal degradation. Autophagy or the autophagic chaperone Hsc70 is dispensable for this pathway. Antibodies against diglycine-modified α-synuclein peptides confirmed that endogenous α-synuclein is similarly ubiquitinated in the brain and targeted to lysosomes in primary and iPSC-derived neurons. Ubiquitinated α-synuclein was detected in Lewy bodies and cellular models of aggregation, suggesting that it may be entrapped with endo/lysosomes in inclusions. Our data elucidate the intracellular trafficking of de novo ubiquitinated α-synuclein and provide tools for investigating the rapidly turned-over fraction of this disease-causing protein.

DOI

10.1126/sciadv.add8910

Type

Journal article

Journal

Sci Adv

Publication Date

16/06/2023

Volume

9

Keywords

alpha-Synuclein, Endosomes, Ubiquitination, Ubiquitin, Lysosomes, Endosomal Sorting Complexes Required for Transport

Permalink Original publication