Tyrosine and serine phosphorylation of α-synuclein have opposing effects on neurotoxicity and soluble oligomer formation
Li Chen, Magali Periquet, Xu Wang, Alessandro Negro, Pamela J. McLean, Bradley T. Hyman, Mel B. Feany
Li Chen, Magali Periquet, Xu Wang, Alessandro Negro, Pamela J. McLean, Bradley T. Hyman, Mel B. Feany
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Research Article Neuroscience

Tyrosine and serine phosphorylation of α-synuclein have opposing effects on neurotoxicity and soluble oligomer formation

Abstract

Mutations in the neuronal protein α-synuclein cause familial Parkinson disease. Phosphorylation of α-synuclein at serine 129 is prominent in Parkinson disease and influences α-synuclein neurotoxicity. Here we report that α-synuclein is also phosphorylated at tyrosine 125 in transgenic Drosophila expressing wild-type human α-synuclein and that this tyrosine phosphorylation protects from α-synuclein neurotoxicity in a Drosophila model of Parkinson disease. Western blot analysis of fly brain homogenates showed that levels of soluble oligomeric species of α-synuclein were increased by phosphorylation at serine 129 and decreased by tyrosine 125 phosphorylation. Tyrosine 125 phosphorylation diminished during the normal aging process in both humans and flies. Notably, cortical tissue from patients with the Parkinson disease–related synucleinopathy dementia with Lewy bodies showed less phosphorylation at tyrosine 125. Our findings suggest that α-synuclein neurotoxicity in Parkinson disease and related synucleinopathies may result from an imbalance between the detrimental, oligomer-promoting effect of serine 129 phosphorylation and a neuroprotective action of tyrosine 125 phosphorylation that inhibits toxic oligomer formation.

Authors

Li Chen, Magali Periquet, Xu Wang, Alessandro Negro, Pamela J. McLean, Bradley T. Hyman, Mel B. Feany

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Figure 1

Blocking tyrosine phosphorylation increases α-synuclein toxicity.

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Blocking tyrosine phosphorylation increases α-synuclein toxicity. (A) Th...
(A) The PY125 antibody specifically recognizes phosphorylated Tyr125. Phenylalanine substitution at Tyr125 eliminates immunoreactivity. Lane 1, α-synWT; lane 2, α-synY125F. The same membrane was stripped and reprobed with a phosphorylation-independent α-synuclein antibody (anti-syn). (B) The α-synYF mutant effectively eliminates anti-PY125 immunoreactivity. Compare lane 1 (α-synWT) with lane 3 (α-synY125F). Lane 2 (α-synWT) is the same as lane 1 except for pretreatment with phosphatase. Flies were 20 days old. (C) Quantitative analysis of TH-immunoreactive dorsomedial dopamine neurons over time in transgenic flies. Values represent mean ± SEM. Accelerated loss of TH-immunoreactive neurons is observed in 10-day-old α-synYF transgenic flies (*P < 0.05, multivariant ANOVA with supplementary Newman-Keuls test). The driver in A–C was elav-GAL4. (D and E) Blocking tyrosine phosphorylation enhances retinal degeneration. Tangential section through the retina of an aged adult fly expressing α-synWT shows mild architectural distortion (D), whereas expression of α-synYF produced a greater loss of retinal integrity with large vacuoles (E). Original magnification in D and E, ×400. (F) Quantitative comparison demonstrating significant reduction in the percentage of normal photoreceptor clusters in α-synYF transgenic flies (*P < 0.01, multivariant ANOVA with supplementary Newman-Keuls test). Flies were 30 days old. The driver in D–F was GMR-GAL4. (G) Accelerated loss of climbing ability in transgenic flies expressing α-synS129D and α-synYF throughout the nervous system (elav-GAL4 driver). Asterisks indicate climbing scores that are significantly different from the control and wild-type α-synuclein transgenic scores (*P < 0.01, multivariant ANOVA with supplementary Newman-Keuls test). Control genotype: elav-GAL4/+. Error bars in F and G represent SEM.