Assembly of lysine 63-linked ubiquitin conjugates by phosphorylated α-synuclein implies Lewy body biogenesis

Abstract

α-Synuclein (α-syn) and ubiquitin (Ub) are major protein components deposited in Lewy bodies (LBs) and Lewy neurites, which are pathologic hallmarks of idiopathic Parkinson disease (PD). Almost 90% of α-syn in LBs is phosphorylated at serine 129 (Ser129). However, the role of Ser129-phosphorylated α-syn in the biogenesis of LBs remains unclear. Here, we show that compared with coexpression of wild type (WT) α-syn and Ub, coexpression of phospho-mimic mutant α-syn (S129D) and Ub in neuro2a cells results in an increase of Ub-conjugates and the formation of ubiquitinated inclusions. Furthermore, S129D α-syn fails to increase the Ub-conjugates and form ubiquitinated inclusions in the presence of a K63R mutant Ub. In addition, as compared with WT α-syn, S129D α-syn increased cytoplasmic and neuritic aggregates of itself in neuro2a cells treated with H2O2 and serum deprivation. These results suggest that the contribution of Ser129-phosphorylated α-syn to the Lys63-linked Ub-conjugates and aggregation of itself may be involved in the biogenesis of LBs in Parkinson disease and other related synucleinopathies. © 2007 by The American Society for Biochemistry and Molecular Biology, Inc.