Transgenic mice expressing S129 phosphorylation mutations in α-synuclein

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Alpha-synuclein aggregation into Lewy bodies is central to Parkinson's disease pathology.
• Most neuronal alpha-synuclein is unphosphorylated, while Lewy body alpha-synuclein is predominantly phosphorylated at serine 129 (S129).

Purpose of the Study:

• To investigate the functional consequences of alpha-synuclein phosphorylation at S129.
• To determine if mimicking or blocking S129 phosphorylation affects alpha-synuclein's synaptic localization, vesicle distribution, and early Parkinson's disease markers.

Main Methods:

• Developed transgenic mice expressing human SNCA with phosphomimic (S129D) or non-phosphorylatable (S129A) mutations on a mouse Snca knockout background.
• Assessed synaptic localization, presynaptic vesicle distribution, colonic motility, and alpha-synuclein aggregation in mutant mice.
• Maintained physiological expression levels to avoid toxic overexpression.

Main Results:

• Mice expressing only the S129A or S129D mutant alpha-synuclein protein exhibited no detectable abnormalities.
• No significant changes in synaptic localization, vesicle distribution, colonic motility, or aggregate formation were observed in either mutant line.
• The S129A and S129D mutations did not appear to impact alpha-synuclein function in vivo.

Conclusions:

• Alpha-synuclein phosphorylation at S129, or the inability to phosphorylate it, does not cause overt pathology in this mouse model.
• These findings suggest that S129 phosphorylation is not essential for normal alpha-synuclein function or the absence of pathology in the studied contexts.