Promega NanoLuc Enables a First in Measuring Drug-Target Residence in Live Cells

A recently published paper using Promega NanoLuc(r) technology describes the first method to directly assess the dynamic process of target engagement in live cancer cells.

Promega Scientists have developed a NanoLuc-based method for use in drug discovery that measures target residence as a key aspect of target engagement in live cells. The technology uses bioluminescence resonance energy transfer (BRET), and allows measurement of drug binding to protein targets in real time and within live cells.

Directly Measuring Target Engagement

Measuring target protein-drug occupancy in cells and correlating this target engagement with desired pharmacologic effects is important in drug discovery. NanoBRET(tm) technology provides a simple method to directly assess target engagement. "The NanoBRET system allowed me to measure engagement of our chemical inhibitors directly to our target in living cells and I am excited to apply the technique to other targets," said Graeme Walker, Team Leader, Cellular Pharmacology Drug Discovery Unit at the Cancer Research UK Manchester Institute.

Measuring Target Residence in Live Cells

An even greater benefit of NanoBRET technology is the ability to measure target residence time, which is the duration of drug-protein interaction. It allows researchers to optimize drugs for enhanced action despite clearance from the system. Walker added, "[The NanoBRET technology] provided a simple means to measure compound residence time at the target while keeping the cells intact. This capability allowed our project team to elucidate a novel mechanism of action for our chemical probes."

How NanoBRET Target Engagement Works

To detect drug-target interactions, NanoBRET target engagement uses cell-permeable fluorescent tracers designed to interact with NanoLuc-tagged target proteins. The result of interaction is energy transfer from the NanoLuc protein to the tracer, generating a measurable signal. If a small molecule drug candidate interacts with the target protein, the tracer and drug compete for binding and BRET signal diminishes. Residence time measurement relies on pre-equilibration of compound with cells, removal of excess compound, and addition of tracer. Real-time signal monitoring shows compounds with slow target dissociation impede tracer binding and slow BRET signal production.

For more information on the NanoBRET Target Engagement Technology, visit Promega here.