Visualizing the trans-synaptic arrangement of synaptic proteins by expansion microscopy

Area of Science:

• Neuroscience
• Cell Biology
• Microscopy

Background:

• High-fidelity synaptic neurotransmission relies on precise spatial organization of synaptic proteins.
• Trans-synaptic nanocolumns are hypothesized to facilitate efficient information transfer but are challenging to visualize due to their small size.

Purpose of the Study:

• To develop a method for visualizing trans-synaptic nanocolumns with high resolution.
• To enable the study of pathological alterations in nanocolumn structure, particularly in LGI1-antibody associated limbic encephalitis.

Main Methods:

• Combined post-gelation immunolabeling with expansion microscopy (ExM) for sample expansion.
• Utilized Airyscan super-resolution microscopy on ~8-fold expanded samples for multicolor fluorescence imaging.
• Achieved 20-40 nm spatial resolution, enabling visualization of protein complexes and nanocolumns.

Main Results:

• Successfully visualized trans-synaptic nanocolumns by combining ExM and Airyscan super-resolution microscopy.
• Demonstrated increased labeling efficiency and improved visualization of nanoscale protein organization.
• Showcased the method's utility in studying diseases affecting synaptic structure, such as LGI1-antibody encephalitis.

Conclusions:

• The developed post-gelation immunolabeling ExM combined with Airyscan microscopy provides unprecedented resolution for synaptic structures.
• This technique overcomes previous visualization challenges, allowing detailed study of nanocolumns.
• The approach is valuable for investigating synaptic pathology in neurological disorders.