Simultaneous imaging of multiple cellular events using high-accuracy fluorescence polarization microscopy.

Area of Science:

• Biophysics
• Molecular Biology
• Cell Biology

Background:

• Förster resonance energy transfer (FRET) is crucial for designing biomolecular indicators.
• Conventional hetero-FRET indicators, using multiple fluorophores, limit simultaneous multicolor imaging.
• Existing methods face challenges in quantitative measurements and multicolor visualization.

Purpose of the Study:

• To develop a novel homo-FRET calcium indicator (W-Cameleon) overcoming limitations of hetero-FRET systems.
• To enable simultaneous visualization of multiple intracellular events.
• To enhance quantitative understanding of biological phenomena through advanced imaging.

Main Methods:

• Developed a homo-FRET calcium indicator (W-Cameleon) using two identical yellow fluorescent proteins.
• Engineered a microscopy technique to precisely detect fluorescence anisotropy changes.
• Utilized photonic-crystal technology to compensate for fluorescence depolarization.

Main Results:

• W-Cameleon exhibits Ca2+-dependent changes in FRET efficiency, detected as fluorescence anisotropy.
• The developed microscopy technique achieves high-precision anisotropy detection.
• Successfully visualized three simultaneous intracellular events using three distinct fluorescent indicators.

Conclusions:

• Homo-FRET indicators offer advantages over hetero-FRET for multicolor imaging.
• The W-Cameleon system expands the capacity for observing simultaneous biological events.
• This approach facilitates a more quantitative understanding of complex cellular processes.