eSylites: Synthetic Probes for Visualization and Topographic Mapping of Single Excitatory Synapses

Area of Science:

• Neuroscience
• Molecular Biology
• Biochemistry

Background:

• The postsynaptic density (PSD) organization is crucial for synaptic transmission and brain function.
• Limitations in visualizing nanometer-scaled synaptic structures are due to the size of conventional imaging probes like antibodies and fluorescent tags.

Purpose of the Study:

• To develop novel, small, high-affinity synthetic probes for high-contrast visualization of excitatory synapses.
• To overcome the spatial resolution limitations imposed by larger biomolecular probes.

Main Methods:

• Development and in vitro characterization of fluorescent bivalent peptides (eSylites).
• Evaluation of eSylites' cellular target selectivity and binding affinity using microscopy on primary neurons and brain slices.
• Application of eSylites at nanomolar concentrations for PSD-95 visualization.

Main Results:

• eSylites demonstrated remarkable cellular target selectivity and high affinity for PSD-95.
• The probes enabled simplified, high-contrast visualization of excitatory synapses with minimized spatial dye offset.
• Improved localization precision and time-resolved discrimination of PSD-95 were achieved, revealing distinct nanodomains within dendritic spines.

Conclusions:

• eSylites represent a broadly applicable tool for simplified visualization of excitatory synapses.
• These probes are compatible with high-end microscopy, enabling unprecedented resolution of PSD organization.
• The findings facilitate a deeper understanding of synaptic plasticity and information processing in the brain.