title: Casein kinase II-mediated phosphorylation regulates alpha-synuclein/synphilin-1 interaction and inclusion body formation.
abstract: Alpha-synuclein is a phosphoprotein that accumulates as a major component of Lewy bodies in the brains of patients with Parkinson disease. Synphilin-1, which is also present in Lewy bodies, binds with alpha-synuclein and forms cytoplasmic inclusions in transfected cells. Yet the molecular determinants of this protein-protein interaction are unknown. Here we report that casein kinase II (CKII) phosphorylates synphilin-1 and that the beta subunit of this enzyme complex binds to synphilin-1. Additionally, both CKII alpha and beta subunits are present within cytoplasmic inclusions in cells that overexpress synphilin-1. Notably, the interaction between synphilin-1 and alpha-synuclein is markedly dependent on phosphorylation. Inhibition of CKII activity by 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole blocks the binding between these two proteins and significantly reduces the percentage of cells that contain eosinophilic cytoplasmic inclusions. Mutation of the major CKII phosphorylation site in alpha-synuclein (S129A) has no significant impact on the binding between alpha-synuclein and synphilin-1 or on the formation of synphilin-1/alpha-synuclein-positive inclusions. These data suggest that the CKII-mediated phosphorylation of synphilin-1 rather than that of alpha-synuclein is critical in modulating their tendency to aggregate into inclusions. These observations collectively indicate that a ubiquitous post-translational modification such as phosphorylation can regulate inclusion body formation in the context of alpha-synuclein and synphilin-1 interaction.
authors.affiliation: Genetic Pharmacology Unit, NINDS, National Institutes of Health, Bethesda, Maryland 20824, USA.
authors.forename: Gwang
authors.initials: G
authors.lastname: Lee
authors.forename: Mikiei
authors.initials: M
authors.lastname: Tanaka
authors.forename: Kiho
authors.initials: K
authors.lastname: Park
authors.forename: Sang Seop
authors.initials: SS
authors.lastname: Lee
authors.forename: Yong Man
authors.initials: YM
authors.lastname: Kim
authors.forename: Eunsung
authors.initials: E
authors.lastname: Junn
authors.forename: Sang-Hyeon
authors.initials: SH
authors.lastname: Lee
authors.forename: M Maral
authors.initials: MM
authors.lastname: Mouradian
mesh_terms: D000818:Animals; D001665:Binding Sites; D015153:Blotting, Western; D002352:Carrier Proteins / Q000737:chemistry; D047390:Casein Kinase II; D002460:Cell Line; D003593:Cytoplasm / Q000378:metabolism; D004004:Dichlororibofuranosylbenzimidazole / Q000737:chemistry; D006801:Humans; D007150:Immunohistochemistry; D008856:Microscopy, Fluorescence; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism*; D016716:PC12 Cells; D010766:Phosphorylation; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D012694:Serine / Q000737:chemistry; D051843:Synucleins; D014162:Transfection; D051844:alpha-Synuclein
chemical_list: D002352:Carrier Proteins; D009419:Nerve Tissue Proteins; C497604:SNCA protein, human; C118958:SNCAIP protein, human; C497606:Snca protein, rat; C498463:Sncaip protein, rat; D051843:Synucleins; D051844:alpha-Synuclein; D012694:Serine; D004004:Dichlororibofuranosylbenzimidazole; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases