Label-Free Dynamic Mass Redistribution Assay To Characterize Holistic Chemokine Receptor Pharmacology in Neutrophils

In a study published in this issue of JPET, Stott et al. (2024) investigated the capacity of the label-free dynamic mass redistribution (DMR) assay to accurately characterize chemokine receptor pharmacology in primary neutrophils and the extent to which this approach offers advantages over traditional high-throughput screening methodologies. Screening for molecules to modulate activity of a target protein is a vital step of the modern drug discovery process. Initial screening campaigns usually involve testing thousands to millions of drug-like molecules for desired effects in high-throughput assays (Addis et al., 2023). Such assays are commonly based on cellular approaches where cell lines overexpress recombinant target proteins such as G protein-coupled receptors (GPCRs), tyrosine kinase receptors, ion channels, transporters, enzymes, etc. Alternatively, some high-throughput assays are conducted directly on purified target proteins. In cell-based assays, activation of the target protein leads to recruitment of effector proteins and initiation of downstream signaling events, which can be measured using a variety of techniques. Most of these detection techniques require some form of labeling, either of the target protein itself or the detection reagents/biosensors. For example, interactions between the target and effector proteins can be followed by proximity assays [i.e., split enzyme complementation, bioluminescence resonance energy transfer (BRET), and fluorescence resonance energy transfer (FRET)] where each protein is labeled in such a way that a specific signal is generated when the two proteins associate. Essential for all high-throughput assays is a high signal-to-noise ratio and the ability to be miniaturized to a format that allows thousands of molecules to be tested at the same time (Addis et al., 2023).