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Updated: Aug 18, 2026
Studying Pre-formed Fibril Induced α-Synuclein Accumulation in Primary Embryonic Mouse Midbrain Dopamine Neurons
Published on: August 16, 2020
Reversible inhibition of alpha-synuclein fibrillization by dopaminochrome-mediated conformational alterations
Erin H Norris1, Benoit I Giasson, Roberto Hodara
1Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Institute on Aging, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Abstract:
Previous studies demonstrated that alpha-synuclein (alpha-syn) fibrillization is inhibited by dopamine, and studies to understand the molecular basis of this process were conducted (Conway, K. A., Rochet, J. C., Bieganski, R. M., and Lansbury, P. T., Jr. (2001) Science 294, 1346-1349). Dopamine inhibition of alpha-syn fibrillization generated exclusively spherical oligomers that depended on dopamine autoxidation but not alpha-syn oxidation, because mutagenesis of Met, His, and Tyr residues in alpha-syn did not abrogate this inhibition. However, truncation of alpha-syn at residue 125 restored the ability of alpha-syn to fibrillize in the presence of dopamine. Mutagenesis and competition studies with specific synthetic peptides identified alpha-syn residues 125-129 (i.e. YEMPS) as an important region in the dopamine-induced inhibition of alpha-syn fibrillization. Significantly, the dopamine oxidation product dopaminochrome was identified as a specific inhibitor of alpha-syn fibrillization. Dopaminochrome promotes the formation of spherical oligomers by inducing conformational changes, as these oligomers regained the ability to fibrillize by simple denaturation/renaturation. Taken together, these data indicate that dopamine inhibits alpha-syn fibrillization by inducing structural changes in alpha-syn that can occur through the interaction of dopaminochrome with the 125YEMPS129 motif of alpha-syn. These results suggest that the dopamine autoxidation can prevent alpha-syn fibrillization in dopaminergic neurons through a novel mechanism. Thus, decreased dopamine levels in substantia nigra neurons might promote alpha-syn aggregation in Parkinson's disease.
Insights
Dopamine prevents alpha-synuclein (alpha-syn) aggregation by forming spherical oligomers. This inhibition involves dopamine oxidation products interacting with the alpha-syn YEMPS motif, potentially explaining Parkinson's disease links.
Area of Science:
- Neuroscience
- Biochemistry
- Molecular Biology
Background:
- Alpha-synuclein (alpha-syn) fibrillization is implicated in Parkinson's disease pathogenesis.
- Previous studies indicated dopamine inhibits alpha-syn fibrillization.
Purpose of the Study:
- To elucidate the molecular mechanisms underlying dopamine's inhibition of alpha-syn fibrillization.
- To identify specific regions and molecular interactions involved in this inhibitory process.
Main Methods:
- Investigated dopamine's effect on alpha-syn fibrillization using mutagenesis and truncation studies.
- Analyzed the role of dopamine autoxidation and alpha-syn oxidation.
- Identified alpha-syn residues 125-129 (YEMPS) and dopamine oxidation products (dopaminochrome) using peptide competition and biochemical assays.
Main Results:
- Dopamine inhibition of alpha-syn fibrillization yielded spherical oligomers dependent on dopamine autoxidation.
- Mutagenesis of Met, His, and Tyr residues in alpha-syn did not prevent inhibition.
- Truncation at residue 125 restored fibrillization; the YEMPS motif (residues 125-129) was critical for inhibition.
- Dopaminochrome, a dopamine oxidation product, was identified as a specific alpha-syn fibrillization inhibitor.
- Dopaminochrome induced conformational changes in alpha-syn, forming reversible spherical oligomers.
Conclusions:
- Dopamine inhibits alpha-syn fibrillization via dopaminochrome interaction with the alpha-syn YEMPS motif, inducing structural changes.
- This novel mechanism suggests dopamine autoxidation can prevent alpha-syn aggregation in dopaminergic neurons.
- Reduced dopamine levels in substantia nigra neurons may thus promote alpha-syn aggregation in Parkinson's disease.
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