Facile "stop codon" method reveals elevated neuronal toxicity by discrete S87p-α-synuclein oligomers

Area of Science:

• Neuroscience
• Biochemistry
• Protein Chemistry

Background:

• Alpha-synuclein (α-Syn) aggregation is implicated in neurodegenerative diseases.
• Specific phosphorylation sites on α-Syn may influence its aggregation and toxicity.
• Understanding these modifications is crucial for developing therapeutic strategies.

Purpose of the Study:

• To develop a method for site-specific phosphorylation of α-Syn.
• To investigate the impact of phosphorylation at Serine 87 and Serine 129 on α-Syn oligomerization and cellular toxicity.
• To evaluate the inhibitory effect of pyridoxal 5 omino-phosphate on α-Syn aggregation and toxicity.

Main Methods:

• Site-specific phosphorylation of α-Syn using the 'stop codon' method.
• Verification of phosphorylated α-Syn species by LC/MS/MS and immunoblotting.
• Assessment of oligomerization via SDS-PAGE and cellular toxicity using WST-1 assays on SH-SY5Y cells.
• Investigation of aggregation inhibition by pyridoxal 5 omino-phosphate.

Main Results:

• Phosphorylated α-Syn oligomers, particularly S87p-α-Syn and S87p,129p-α-Syn, exhibited higher cellular toxicity than non-phosphorylated α-Syn oligomers.
• Aggregation induced by dopamine (DA) or DA/Cu(2+) showed similar trends for both phosphorylated and non-phosphorylated α-Syn.
• Pyridoxal 5 omino-phosphate demonstrated significant inhibition of α-Syn aggregation and reduced cellular toxicity.

Conclusions:

• Phosphorylation of α-Syn at residue 87 contributes to increased neuronal toxicity.
• Pyridoxal 5 omino-phosphate serves as a potential inhibitor for α-Syn aggregation and associated toxicity.
• Targeting specific phosphorylation sites and utilizing inhibitors like pyridoxal 5 omino-phosphate may offer therapeutic avenues for α-Syn-related disorders.