Challenge: Ion channels are involved in numerous physiological functions, and as drug targets have been implicated in a wide range of pathological conditions. However, despite considerable effort, channel-targeted drug discovery has been hampered by the absence of adequate tools to functionally screen molecules that can modulate channel activity.

Solution: The researchers have developed an innovative approach to identify compounds that can influence channel function. The method relies on real-time assessments of ion-channel conformational responses and structural rearrangements of channel subunits upon binding to different ligands. Using the highly sensitive bioluminescence resonance energy transfer (BRET) technology, the researchers have generated 20 BRET constructs for different Kir3 ion channel subunits. They validated their system by showing the correlation of dose response curves generated in BRET assays with ion flux assays, a technique commonly used by the industry to evaluate channel modulators.

Achievements/Impact: The data generated showed a high level of correlation between ligand-induced BRET changes, indicative of conformational rearrangement of channel subunits and readouts in ion flux assays. Indeed, the Kir3 biosensors generated in this study were shown to discern interactions among known Kir3 channel ligands, thereby validating the utility of the technology. These novel tools may offer the opportunity to develop a new generation of channel modulators with novel mechanisms of action and could potentially predict phenotypic responses from conformational profiles at the early stages of hit-to-lead optimization. Finally, the technology may also be adapted to interrogate other classes of multimeric channels, including ion-gated channels, TRPV and P2X, as well as voltage-gated channels (K+ or Ca++).