Time-lapse FRET microscopy using fluorescence anisotropy.

Area of Science:

• Cellular Biology
• Immunology
• Biophysics

Background:

• Rac1 is a key regulator of T-cell activation and immune responses.
• Traditional Förster resonance energy transfer (FRET) methods have limitations in temporal resolution and require spectral corrections.
• Dynamic imaging of protein activity is crucial for understanding cellular signaling.

Purpose of the Study:

• To present a novel method for dynamic imaging of Rac1 activity in live T-cells.
• To demonstrate the capability of a multi-functional high-content screening instrument for monitoring protein-protein interactions.
• To achieve high temporal resolution in measuring T-cell responses.

Main Methods:

• Utilized Förster resonance energy transfer (FRET) between enhanced green and monomeric red fluorescent proteins as a biosensor for Rac1 activity.
• Employed a multi-functional high-content screening instrument with fluorescence anisotropy.
• Measured T-cell responses upon stimulation via cell surface receptor interaction with antibody-coated plates.

Main Results:

• Observed dynamic changes in biosensor activity reflecting Rac1 activity in real-time.
• Achieved high temporal resolution, surpassing traditional FRET methodologies.
• Demonstrated a method that bypasses the need for spectral corrections typically required for intensity-based measurements.

Conclusions:

• The developed FRET-based biosensor and microscopy approach enables high-temporal-resolution monitoring of Rac1 activity in live T-cells.
• This method provides a significant advancement over conventional techniques for studying dynamic cellular processes.
• The findings offer new insights into T-cell signaling and immune responses.