Pathogenic Mutations Differentially Regulate Cell-to-Cell Transmission of α-Synuclein

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Pathological alpha-synuclein (α-syn) cell-to-cell spread is implicated in Parkinson's disease (PD) pathogenesis.
• α-syn gene mutations are linked to earlier PD onset and increased severity.
• The precise mechanisms by which these mutations accelerate PD progression remain unclear.

Purpose of the Study:

• To investigate how eight pathogenic α-syn mutations affect its intercellular transmission and cytotoxicity.
• To elucidate the molecular mechanisms underlying mutation-driven PD pathogenesis.
• To explore potential therapeutic targets by understanding α-syn propagation.

Main Methods:

• Examined eight human α-syn mutations (A18T, A29S, A30P, E46K, H50Q, G51D, A53E, A53T) in neuroblastoma cells, neurons, and microglia.
• Assessed α-syn secretion, aggregation, intracellular levels after preformed fibril (PFF) treatment, cytotoxicity, seeding, and neuroinflammation induction.
• Utilized in vitro assays and in vivo models including the rat substantia nigra pars compacta.

Main Results:

• Mutations H50Q and A53T significantly increased α-syn secretion; six mutations showed a trend toward enhanced secretion.
• H50Q strongly promoted α-syn aggregation, while G51D delayed it.
• Mutations E46K, H50Q, and G51D increased intracellular α-syn levels upon PFF treatment.
• H50Q, G51D, and A53T PFFs efficiently seeded in vivo and induced neuroinflammation.

Conclusions:

• Pathogenic α-syn mutations augment prion-like spread at various stages, contributing to PD.
• Targeting and blocking this enhanced α-syn propagation presents a promising therapeutic avenue for Parkinson's disease.
• Understanding mutation-specific effects on α-syn transmission is crucial for developing effective PD treatments.