Fluorescent Membrane Tension Probes for Early Endosomes

Area of Science:

• Cell biology
• Biophysics
• Molecular imaging

Background:

• Fluorescent flipper probes are emerging tools for imaging membrane tension in live cells.
• Targeting probes to specific cellular compartments like early endosomes (EEs) is crucial but challenging.
• Existing probes struggle with EE retention due to their neutralization in weakly acidic environments.

Purpose of the Study:

• To develop a protein-engineering-free strategy for targeting fluorescent probes to early endosomes (EEs).
• To create novel EE-targeting probes that overcome retention issues in weakly acidic EE environments.
• To enable the study of endocytosis mechanics using targeted membrane tension imaging.

Main Methods:

• Design and synthesis of a novel fluorescent flipper probe incorporating a substituted benzylamine head group with a higher pK_a.
• Validation of the probe's ability to target and be retained in early endosomes (EEs).
• Assessment of the probe's preserved mechanosensitivity for membrane tension imaging.

Main Results:

• A rational strategy was developed to target fluorescent probes to early endosomes (EEs) using a specific head group.
• The novel probes demonstrate effective retention in EEs, unlike previously used probes.
• The developed EE flipper probes maintain their mechanosensitivity for imaging membrane tension.

Conclusions:

• A new class of fluorescent probes has been engineered for specific early endosome (EE) targeting.
• These probes offer a valuable tool for studying the mechanics of endocytosis and other EE-related processes.
• The strategy provides a non-protein engineering approach for targeted live-cell membrane tension imaging.