Multicolor FRET-FLIM Microscopy to Analyze Multiprotein Interactions in Live Cells

Area of Science:

• Cellular Biology
• Biophysics
• Molecular Imaging

Background:

• Understanding live-cell signaling pathways is vital for targeted medicine development.
• Protein interactions within complex signaling cascades require precise subcellular localization and real-time observation.
• Existing invasive methods limit the study of dynamic protein interactions in their natural cellular environment.

Purpose of the Study:

• To develop and utilize advanced imaging techniques for real-time, noninvasive visualization of protein-protein interactions.
• To overcome the limitations of traditional cell disruption assays.
• To investigate multiple protein interactions within the mTORC1 signaling pathway.

Main Methods:

• Development and application of two-channel pulsed interleaved excitation (PIE) combined with Förster resonance energy transfer (FRET) and fluorescence lifetime imaging microscopy (FLIM).
• Tagging proteins with multiple fluorescent protein derivatives.
• Monitoring changes in donor fluorophore excited-state lifetime to detect FRET-induced quenching, indicating physical interaction.

Main Results:

• The FRET-FLIM combination provides enhanced information compared to standard FRET by analyzing fluorescence lifetime changes.
• Successful application of the PIE-FRET-FLIM method for observing multiple protein interactions within the mTORC1 pathway.
• Demonstrated real-time, nanoscale visualization of protein interactions in living cells.

Conclusions:

• FRET-FLIM offers a powerful, noninvasive approach for studying dynamic protein interactions in live cells.
• This technique significantly improves the understanding of complex cellular signaling networks.
• The developed method is crucial for advancing drug discovery and understanding cell function.