Serine 129 phosphorylation reduces the ability of alpha-synuclein to regulate tyrosine hydroxylase and protein phosphatase 2A in vitro and in vivo.
Alpha-synuclein (a-Syn), a protein implicated in Parkinson disease, contributes significantly to dopamine metabolism. a-Syn binding inhibits the activity of tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine synthesis. Phosphorylation of TH stimulates its activity, an effect that is reversed by protein phosphatase 2A (PP2A). In cells, a-Syn overexpression activates PP2A. Here we demonstrate that a-Syn significantly inhibited TH activity in vitro and in vivo and that phosphorylation of a-Syn serine 129 (Ser-129) modulated this effect. In MN9D cells, a-Syn overexpression reduced TH serine 19 phosphorylation (Ser(P)-19). In dopaminergic tissues from mice overexpressing human a-Syn in catecholamine neurons only, TH-Ser-19 and TH-Ser-40 phosphorylation and activity were also reduced, whereas PP2A was more active. Cerebellum, which lacks excess a-Syn, had PP2A activity identical to controls. Conversely, a-Syn knock-out mice had elevated TH-Ser-19 phosphorylation and activity and less active PP2A in dopaminergic tissues. Using an a-Syn Ser-129 dephosphorylation mimic, with serine mutated to alanine, TH was more inhibited, whereas PP2A was more active in vitro and in vivo. Phosphorylation of a-Syn Ser-129 by Polo-like-kinase 2 in vitro reduced the ability of a-Syn to inhibit TH or activate PP2A, identifying a novel regulatory role for Ser-129 on a-Syn. These findings extend our understanding of normal a-Syn biology and have implications for the dopamine dysfunction of Parkinson disease.
Lou
Haiyan
H
Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.
Montoya
Susana E
SE
Alerte
Tshianda N M
TN
Wang
Jian
J
Wu
Jianjun
J
Peng
Xiangmin
X
Hong
Chang-Sook
CS
Friedrich
Emily E
EE
Mader
Samantha A
SA
Pedersen
Courtney J
CJ
Marcus
Brian S
BS
McCormack
Alison L
AL
Di Monte
Donato A
DA
Daubner
S Colette
SC
Perez
Ruth G
RG
D000818:Animals; D004298:Dopamine / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D016086:Lentivirus / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D016296:Mutagenesis; D018377:Neurotransmitter Agents / Q000378:metabolism; D010300:Parkinson Disease / Q000378:metabolism; D010766:Phosphorylation; D054648:Protein Phosphatase 2 / Q000737:chemistry*; D012694:Serine / Q000737:chemistry*; D014443:Tyrosine / Q000737:chemistry; D014446:Tyrosine 3-Monooxygenase / Q000737:chemistry*; D051844:alpha-Synuclein / Q000737:chemistry*
D018377:Neurotransmitter Agents; D051844:alpha-Synuclein; D014443:Tyrosine; D012694:Serine; D014446:Tyrosine 3-Monooxygenase; D054648:Protein Phosphatase 2; D004298:Dopamine