Visualization and Quantitative Analysis of G Protein-Coupled Receptor−β-Arrestin Interaction in Single Cells and Specific Organs of Living Mice Using Split Luciferase Complementation

Methods used to assess the efficacy of potentially therapeutic reagents for G protein-coupled receptors (GPCRs) have been developed. Previously, we demonstrated sensitive detection of the interaction of GPCRs and β-arrestin2 (ARRB2) using 96-well microtiter plates and a bioluminescence microscope based on split click beetle luciferase complementation. Herein, using firefly luciferase emitting longer wavelength light, we demonstrate quantitative analysis of the interaction of β2-adrenergic receptor (ADRB2), a kind of GPCR, and ARRB2 in a 96-well plate assay with single-cell imaging. Additionally, we showed bioluminescence <i>in vivo</i> imaging of the ADRB2–ARRB2 interaction in two systems: cell implantation and hydrodynamic tail vein (HTV) methods. Specifically, in the HTV method, the luminescence signal from the liver upon stimulation of an agonist for ADRB2 was obtained in the intact systems of mice. The results demonstrate that this method enables noninvasive screening of the efficacy of chemicals at the specific organ in <i>in vivo</i> testing. This <i>in vivo</i> system can contribute to effective evaluation in pharmacokinetics and pharmacodynamics and expedite the development of new drugs for GPCRs.