A Comparative Study of Impedance versus Optical Label-Free Systems Relative to Labelled Assays in a Predominantly Gi Coupled GPCR (C5aR) Signalling

Biosensors

Reena Halai¹  Daniel E. Croker¹  Jacky Y. Suen¹  David P. Fairlie¹ 

[1] Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia;

关键词: GPCR;    impedance and optical biosensors;    label-free;    secondary messenger;    signal transduction;   

DOI  :  10.3390/bios2030273

来源: mdpi

【 摘 要 】

Profiling ligand function on G-protein coupled receptors (GPCRs) typically involves using transfected cells over-expressing a target of interest, a labelled ligand, and intracellular secondary messenger reporters. In contrast, label-free assays are sensitive enough to allow detection in native cells, which may provide a more physiologically relevant readout. Here, we compare four agonists (native agonists, a peptide full agonist and a peptide partial agonist) that stimulate the human inflammatory GPCR C5aR. The receptor was challenged when present in human monocyte-derived macrophages (HMDM) versus stably transfected human C5aR-CHO cells. Receptor activation was compared on label-free optical and impedance biosensors and contrasted with results from two traditional reporter assays. The rank order of potencies observed across label-free and pathway specific assays was similar. However, label-free read outs gave consistently lower potency values in both native and transfected cells. Relative to pathway-specific assays, these technologies measure whole-cell responses that may encompass multiple signalling events, including down-regulatory events, which may explain the potency discrepancies observed. These observations have important implications for screening compound libraries against GPCR targets and for selecting drug candidates for in vivo assays.

【 授权许可】

CC BY   
© 2012 by the authors; licensee MDPI, Basel, Switzerland.