Ubiquitin ligase Nedd4 promotes alpha-synuclein degradation by the endosomal-lysosomal pathway.

Journal article

α-Synuclein is an abundant brain protein that binds to lipid membranes and is involved in the recycling of presynaptic vesicles. In Parkinson disease, α-synuclein accumulates in intraneuronal inclusions often containing ubiquitin chains. Here we show that the ubiquitin ligase Nedd4, which functions in the endosomal-lysosomal pathway, robustly ubiquitinates α-synuclein, unlike ligases previously implicated in its degradation. Purified Nedd4 recognizes the carboxyl terminus of α-synuclein (residues 120-133) and attaches K63-linked ubiquitin chains. In human cells, Nedd4 overexpression enhances α-synuclein ubiquitination and clearance by a lysosomal process requiring components of the endosomal-sorting complex required for transport. Conversely, Nedd4 down-regulation increases α-synuclein content. In yeast, disruption of the Nedd4 ortholog Rsp5p decreases α-synuclein degradation and enhances inclusion formation and α-synuclein toxicity. In human brains, Nedd4 is present in pigmented neurons and is expressed especially strongly in neurons containing Lewy bodies. Thus, ubiquitination by Nedd4 targets α-synuclein to the endosomal-lysosomal pathway and, by reducing α-synuclein content, may help protect against the pathogenesis of Parkinson disease and other α-synucleinopathies.

Authors: Tofaris, G; Kim, H; Hourez, R; Jung, J; Kim, K

• Journal: Proceedings of the National Academy of Sciences of the United States of America
• Volume: 108
• Issue: 41
• Pages: 17004-17009
• Publication date: 2011-10-01
• DOI: 10.1073/pnas.1109356108
• EISSN: 1091-6490
• ISSN: 0027-8424
• Language: English
• Keywords: Cell Line; HEK293 Cells; Lewy Bodies; Rats; Endosomal Sorting Complexes Required for Transport; Recombinant Proteins; Mice; Substrate Specificity; Ubiquitin-Protein Ligase Complexes; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; alpha-Synuclein; Brain; Humans; Locus Coeruleus; Ubiquitination; Substantia Nigra; Lysosomes; Molecular Sequence Data; Amino Acid Sequence; Animals; Binding Sites; Endosomes; Ubiquitin-Protein Ligases; Parkinson Disease; Lysine