Early α-Synuclein Heterodimerization Kinetics Predict Parkinson's Disease Onset

Area of Science:

• Biochemistry
• Neuroscience
• Computational Biology

Background:

• Protein aggregation, particularly of alpha-synuclein (αS), is central to Parkinson's disease pathogenesis.
• Linking physicochemical properties of protein aggregation to clinical outcomes like age of onset remains a significant challenge.

Purpose of the Study:

• To investigate if simulated aggregation dynamics of αS can predict the clinical age of onset in Parkinson's disease.
• To identify specific aggregation events and timescales that correlate with disease initiation.

Main Methods:

• Utilized a multiscale simulation framework combining coarse-grained (CG) and atomistic simulations.
• Quantified early dimerization kinetics and estimated dimer interaction energies for wild-type and familial mutant αS.
• Calculated CG thermodynamic protofilament binding free energies and complemented with atomistic calculations.

Main Results:

• The timescale of wild-type and mutant αS heterodimer formation significantly predicted Parkinson's disease age of onset.
• Homodimer formation kinetics and heterodimer protofilament binding affinities showed no predictive power.
• Homodimer protofilament binding free energies correlated moderately, suggesting late-stage fibril stability is not the primary determinant of disease initiation.

Conclusions:

• Early-stage oligomeric dynamics, specifically heterodimer formation timescales, are crucial predictors of clinical Parkinson's disease phenotypes.
• Disease initiation appears to be governed by a two-stage aggregation process, emphasizing the role of early events.
• Findings highlight the importance of considering aggregation kinetics over static fibril stability in understanding neurodegenerative diseases.