Polo-like Kinase 2 (PLK2) Phosphorylates α-Synuclein at Serine 129 in Central Nervous System

Abstract

Several neurological diseases, includingThe importance of ␣-synuclein to the pathogenesis of Parkinson disease (PD) 4 and the related disorder, dementia with Lewy bodies (DLB), is suggested by its association with Lewy bodies and Lewy neurites, the inclusions that characterize these diseases (1)(2)(3), and demonstrated by the existence of mutations that cause syndromes mimicking sporadic PD and DLB (4 -6). Furthermore, three separate mutations cause early onset forms of PD and DLB. It is particularly telling that duplications or triplications of the gene (7-9), which increase levels of ␣-synuclein with no alteration in sequence, also cause PD or DLB.␣-Synuclein has been reported to be phosphorylated on serine residues, at Ser-87 and Ser-129 (10), although to date only the Ser-129 phosphorylation has been identified in the central nervous system (11,12). Phosphorylation at tyrosine residues has been observed by some investigators (13,14) but not by others (10 -12). Phosphorylation at Ser-129 (p-Ser-129) is of particular interest because the majority of synuclein in Lewy bodies contains this modification (15). In addition, p-Ser-129 was found to be the most extensive and consistent modification in a survey of synuclein in Lewy bodies (11). Results have been mixed from studies investigating the function of phosphorylation using S129A and S129D mutations to respectively block and mimic the modification. Although the phosphorylation mimic was associated with pathology in studies in Drosophila (16) and in transgenic mouse models (17, 18), studies using adeno-associated virus vectors to overexpress ␣-synuclein in rat substantia nigra found an exacerbation of pathology with the S129A mutation, whereas the S129D mutation was benign, if not protective (19). Interpretation of these studies is complicated by a recent study showing that the S129D and S129A mutations themselves have effects on the aggregation properties of ␣-synuclein independent of their effects on phosphorylation, with the S129A mutation stimulating fibril formation (20). Clearly, determination of the role of p-Ser-129 phosphorylation would be helped by identification of the responsible kinase. In addition, identification will provide a pathologically relevant way to increase phosphorylation in a cell or animal model.Several kinases have been proposed to phosphorylate ␣-synuclein, including casein kinases 1 and 2 (10, 12, 21) and members of the G-protein-coupled receptor kinase family (22). In this report, we offer evidence that a member of the polo-like kinase (PLK) family, PLK2 (or serum-inducible kinase, SNK), functions as an ␣-synuclein kinase. The ability of PLK2 to directly phosphorylate ␣-synuclein at Ser-129 is established by overexpression in cell culture and by in vitro reaction with the purified kinase. We show that PLK2 phosphorylates ␣-synuclein in cells, including primary neuronal cultures, using a series of kinase inhibitors as well as inhibition of expression with RNA interference. In addition, inhibitor and knock-out studies in mouse brai...

Interplay between Sumoylation and Phosphorylation for Protection against α-Synuclein Inclusions

“…Here, we expressed and analyzed the effects of two of the most efficient human kinases in yeast, i.e. the G protein-coupled kinase GRK5 (21,25) and the Polo-like kinase PLK2 (26,28). Our study revealed a significant increase of ␣Syn phosphorylation at Ser-129 in yeast in the presence of human PLK2 or GRK5 kinases.…”

α-Synuclein interacts with the switch region of Rab8a in a Ser129 phosphorylation-dependent manner

“…S129 can be phosphorylated by a variety of kinases in vitro and in vivo (Waxman and Giasson, 2010). In particular, polo-like kinases quantitatively and selectively phosphorylate αS at S129 and levels of polo-like kinase 2 are increased in the brains of patients with Lewy body disease (Inglis et al, 2009;Mbefo et al, 2010). However, the relevance of αS phosphorylation at S129 for neurotoxicity and disease remains controversial (Basso et al, 2013).…”

Polo-like kinases mediate cell survival in mitochondrial dysfunction

“…Given our observation of PLK2 regulation by calcium in human colon cancer cells and the previous work in models of synaptic plasticity (16), it is notable that the promoter region of PLK2 contains consensus sequences for both calcium-dependent cAMP and antioxidant response elements (CRE and ARE, respectively). The growing evidence for the role of mitochondrial dysfunction in neurodegenerative diseases and the recent report of PLK2-mediated ␣-synuclein phosphorylation, a hallmark of Parkinson's disease and dementia with Lewy bodies, expand the potential role of PLK2 beyond cell cycle regulation and tumorigenesis to diseases of the central nervous system (34).…”