Fluorescence-Based TNFR1 Biosensor for Monitoring Receptor Structural and Conformational Dynamics and Discovery of Small Molecule Modulators.

Inhibition of tumor necrosis factor receptor 1 (TNFR1) is a billion-dollar industry for treatment of autoimmune and inflammatory diseases. As current therapeutics of anti-TNF leads to dangerous side effects due to global inhibition of the ligand, receptor-specific inhibition of TNFR1 signaling is an intensely pursued strategy. To monitor directly the structural changes of the receptor in living cells, we engineered a fluorescence resonance energy transfer (FRET) biosensor by fusing green and red fluorescent proteins to TNFR1. Expression of the FRET biosensor in living cells allows for detection of receptor-receptor interactions and receptor structural dynamics. Using the TNFR1 FRET biosensor, in conjunction with a high-precision and high-throughput fluorescence lifetime detection technology, we developed a time-resolved FRET-based high-throughput screening platform to discover small molecules that directly target and modulate TNFR1 functions. Using this method in screening multiple pharmaceutical libraries, we have discovered a competitive inhibitor that disrupts receptor-receptor interactions, and allosteric modulators that alter the structural states of the receptor. This enables scientists to conduct high-throughput screening through a biophysical approach, with relevance to compound perturbation of receptor structure, for the discovery of novel lead compounds with high specificity for modulation of TNFR1 signaling.