SNAP25 variant I67N: synaptic phenotypes, drug response and proteome changes in human neurons

Area of Science:

• Neuroscience
• Genetics
• Stem Cell Biology

Background:

• SNAREopathies are severe genetic neurodevelopmental disorders impacting synaptic function.
• Current treatments for these disorders are limited to symptom management.
• There is a critical need for human experimental models to develop targeted therapies.

Purpose of the Study:

• To create and characterize human induced pluripotent stem-cell (hiPSC)-derived neurons with a specific SNAP25 pathogenic variant (I67N).
• To investigate the synaptic phenotypes and molecular changes associated with this variant.
• To explore potential therapeutic interventions for SNAREopathies.

Main Methods:

• Generated CRISPR/Cas9-engineered hiPSC lines with the SNAP25 I67N variant.
• Utilized NGN2-driven differentiation into forebrain glutamatergic neurons.
• Performed electrophysiology, immunostaining, and proteomics to analyze synaptic function and protein expression.

Main Results:

• The SNAP25 I67N variant impaired synaptic transmission, reducing evoked and spontaneous release and altering short-term plasticity.
• Distinct synaptic phenotypes were observed compared to another variant (V48F).
• The 4-aminopyridine drug ameliorated the I67N variant-associated synaptic defects.
• Proteomic analysis identified downregulated synaptic proteins, including CALB1 and SCN2A.

Conclusions:

• hiPSC-based models are effective for studying neurodevelopmental disorders and their underlying synaptic mechanisms.
• The study identified specific synaptic transmission deficits caused by the SNAP25 I67N variant.
• Targeting synaptic dysfunction with drugs like 4-aminopyridine shows promise for personalized treatment strategies in SNAREopathies.