Combining TIR and FRET in Molecular Test Systems

Area of Science:

• Biophysics
• Cell Biology
• Pharmacology

Background:

• Pharmaceutical agents significantly impact protein-protein interactions, particularly at cell membranes.
• Förster Resonance Energy Transfer (FRET) can detect changes in molecular conformations and interactions.
• Total Internal Reflection (TIR) excitation enhances FRET measurements for membrane-associated chromophores.

Purpose of the Study:

• To develop and validate a TIR-FRET screening system for analyzing drug-induced changes in membrane protein interactions.
• To assess the sensitivity and efficiency of TIR-FRET compared to traditional methods.
• To evaluate the response of membrane-associated versus cytosolic targets to pharmaceutical agents.

Main Methods:

• Established a membrane-associated test system to probe epidermal growth factor receptor (EGFR) and growth factor receptor-bound protein 2 interactions.
• Utilized the Epac-SH188 sensor for quantitative FRET measurements via spectral analysis and fluorescence lifetime imaging (FLIM).
• Employed TIR excitation for selective illumination of plasma membranes, alongside epi-illumination, and tested a multi-well TIR fluorescence reader.

Main Results:

• TIR excitation provided highly sensitive FRET measurements with minimal background noise.
• The Epac sensor demonstrated faster responses to pharmaceutical agents like Forskolin and NECA at the plasma membrane compared to the cytosol.
• Successful application of TIR-FRET for screening interactions, including GFP with Nile Red, in a multi-well format.

Conclusions:

• TIR-FRET is a powerful and sensitive technique for studying drug effects on membrane protein interactions.
• This method enables rapid, quantitative screening of pharmaceutical agents affecting cellular signaling pathways.
• The developed system holds promise for high-throughput drug discovery and analysis of membrane-associated biological processes.