title: Characterization of kinases involved in the phosphorylation of aggregated α-synuclein.
abstract: α-Synuclein (α-syn) is the major component of pathological inclusions characteristic of several neurodegenerative disorders, such as Parkinson's disease. The major posttranslational modification of α-syn is phosphorylation at S129, and previous studies estimate that approximately 90% of α-syn in proteinaceous, pathological inclusions is phosphorylated at this site. α-Syn can be phosphorylated by polo-like kinases (PLKs) 1-3 and casein kinases (CK) 1 and 2; however, the kinases associated with the hyperphosphorylation of aggregated α-syn are still under debate. Using a high-efficiency cellular model of α-syn aggregate formation, we found that selective inhibitors for CK2 and PLKs each partially inhibited S129 phosphorylation of soluble (nonaggregated) α-syn, but only PLK inhibitors modestly attenuated the phosphorylation of aggregated α-syn. In addition, none of the kinase inhibitors used had a substantial effect on the propensity of α-syn to aggregate. Overexpression of all PLKs promoted robust phosphorylation of soluble α-syn, but none altered the propensity of α-syn to aggregate. Overexpression of only PLK2 increased phosphorylation of aggregated α-syn at S129, which likely is due to increased phosphorylation of soluble α-syn, which then was incorporated into aggregates. Overexpression of PLK1 and treatment with BI2536 resulted in a significant reduction of phosphorylated, aggregated α-syn protein, beyond that of BI2536 treatment alone. These studies suggest that phosphorylation of α-syn is independent of α-syn aggregate formation, that PLK1 is involved in the phosphorylation of aggregated α-syn at S129 in this system, and that mechanisms resulting in hyperphosphorylation of aggregated α-syn appear to be independent of those responsible for the phosphorylation of soluble α-syn.
authors.affiliation: Department of Pharmacology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Elisa A
authors.initials: EA
authors.lastname: Waxman
authors.forename: Benoit I
authors.initials: BI
authors.lastname: Giasson
mesh_terms: D015153:Blotting, Western; D002460:Cell Line; D005455:Fluorescent Antibody Technique; D006801:Humans; D002479:Inclusion Bodies / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D051844:alpha-Synuclein / Q000378:metabolism*
chemical_list: C497604:SNCA protein, human; D051844:alpha-Synuclein; D011494:Protein Kinases