Protein kinase R dependent phosphorylation of α-synuclein regulates its membrane binding and aggregation

Area of Science:

• Neuroscience
• Molecular Biology
• Biochemistry

Background:

• Alpha-synuclein (α-syn) aggregation forms Lewy bodies in Parkinson's disease (PD).
• Monomeric α-syn's role in synaptic vesicle release involves lipid-binding.
• Mechanisms regulating α-syn membrane binding and function are poorly understood.

Purpose of the Study:

• To investigate the role of Protein kinase R (PKR) in phosphorylating α-syn.
• To determine how PKR-mediated phosphorylation affects α-syn's membrane binding and aggregation.
• To explore the therapeutic potential of modulating α-syn phosphorylation.

Main Methods:

• Investigated α-syn phosphorylation by PKR in vitro and in cells.
• Assessed α-syn binding to lipid membranes and brain vesicles.
• Utilized phosphomimetic mutants (Thr64Glu/Thr72Glu) to study phosphorylation effects.
• Examined α-syn oligomerization, fibrillation, and pathology spread in cellular and organotypic slice models.

Main Results:

• PKR phosphorylates α-syn at Ser/Thr residues in its membrane-binding region.
• Phosphorylated α-syn exhibits reduced binding to lipid membranes and brain vesicles.
• Thr64/Thr72 phosphorylation significantly decreases vesicle affinity, enhancing presynaptic vesicle clustering.
• Phosphomimetic α-syn mutants inhibit α-syn aggregation, fibrillation, and trans-synaptic pathology spread.

Conclusions:

• PKR-mediated phosphorylation regulates α-syn's normal and pathological functions, including membrane binding and aggregation.
• Targeting α-syn phosphorylation presents a potential therapeutic strategy for α-syn aggregate-related neurodegenerative diseases.
• Understanding these regulatory mechanisms could benefit patients with Parkinson's disease and dementia with Lewy bodies.