A Role for α-Synuclein in the Regulation of Dopamine Biosynthesis
Open accessAbstract
The α-synuclein gene is implicated in the pathogenesis of Parkinson9s disease. Although α-synuclein function is uncertain, the protein has homology to the chaperone molecule 14-3-3. In addition, α-synuclein can bind to 14-3-3, and both α-synuclein and 14-3-3 bind to many of the same proteins. Because 14-3-3 binds to and activates tyrosine hydroxylase, the rate-limiting enzyme in dopamine (DA) biosynthesis, we explored whether α-synuclein also bound to tyrosine hydroxylase and influenced its activity. Immunoprecipitation revealed an interaction between α-synuclein and tyrosine hydroxylase in brain homogenates and MN9D dopaminergic cells. Colocalization of α-synuclein with tyrosine hydroxylase was confirmed by immunoelectron microscopy. To explore the consequences of the interaction, we measured the effect of recombinant α-synuclein on tyrosine hydroxylase activity in a cell-free system and observed a dose-dependent inhibition of tyrosine hydroxylase by α-synuclein. To measure the impact of α-synuclein on tyrosine hydroxylase in dopaminergic cells, we stably transfected MN9D cells with wild-type or A53T mutant α-synuclein. Overexpression of wild-type or A53T mutant α-synuclein did not significantly alter tyrosine hydroxylase protein levels in our stably transfected cells. However, overexpressing cell lines had significantly reduced tyrosine hydroxylase activity and a corresponding reduction in dopamine synthesis. The reduction in cellular dopamine levels was not caused by increased dopamine catabolism or dopamine efflux. These data suggest that α-synuclein plays a role in the regulation of dopamine biosynthesis, acting to reduce the activity of tyrosine hydroxylase. If so, a loss of soluble α-synuclein, by reduced expression or aggregation, could increase dopamine synthesis with an accompanying increase in reactive dopamine metabolites.
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Soluble α-synuclein physically interacts with TH and maintains the level of phosphorylated TH in a PP2A-dependent manner.
“α-synuclein in the soluble form physically interacts with TH and maintains the level of phosphorylated TH in a PP2A-dependent manner [114,115,116]”
From Degradation of Tyrosine Hydroxylase by the Ubiquitin-Proteasome System in the Pathogenesis of Parkinson’s Disease and Dopa-Responsive Dystonia (2020) · cites this paper as [116]
Aggregation of α-synuclein potentiates TH phosphorylation and reduces total TH protein.
“Such aggregation of α-synuclein presumably potentiates TH phosphorylation and reduces total TH protein [116,122,123].”
From Degradation of Tyrosine Hydroxylase by the Ubiquitin-Proteasome System in the Pathogenesis of Parkinson’s Disease and Dopa-Responsive Dystonia (2020) · cites this paper as [116]
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- Authors
- Perez, R. G., Waymire, J. C., Lin, E., Liu, J. J., Guo, F., & Zigmond, M. J.
- Affiliations
- The University of Texas Health Science Center at Houston (US)
- University of Pittsburgh (US)
- Venue
- The Journal of Neuroscience
- Publisher
- Society for Neuroscience
- Published
- 2002-04-15
- Volume
- 22
- Issue
- 8
- Pages
- 3090-3099
- ISSN
- 0270-6474 (ISSN-L)
- 1529-2401
- OpenAlex
- W4319425454
- Cited by
- 598
- References
- 47
- Citations by year
- 2026: 16 · 2025: 20 · 2024: 31 · 2023: 22 · 2022: 28 · 2021: 37 · 2020: 19 · 2019: 38 · 2018: 27 · 2017: 33 · 2016: 23 · 2015: 25 · 2014: 12 · 2013: 19 · 2012: 13
- FWCI
- 18.03
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- Journal of Neuroscience (publishedVersion)
- Funders
- National Parkinson Foundation
- Parkinsonfonden
- National Institute of Neurological Disorders and Stroke (NS 19608)
- Topics
- Health Sciences › Medicine › Neurology › Parkinson's Disease Mechanisms and Treatments
- Life Sciences › Neuroscience › Cellular and Molecular Neuroscience › Nuclear Receptors and Signaling
- Health Sciences › Medicine › Neurology › Neurological disorders and treatments
- Keywords
- alpha-synuclein, dopamine synthesis, tyrosine hydroxylase, Parkinson's disease, protein-protein interaction, A53T mutant, dopaminergic neurons, MN9D cells, enzyme inhibition, dopamine metabolites
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