1. Academic Validation
  2. NanoBiT Complementation to Monitor Agonist-Induced Adenosine A1 Receptor Internalization

NanoBiT Complementation to Monitor Agonist-Induced Adenosine A1 Receptor Internalization

  • SLAS Discov. 2020 Feb;25(2):186-194. doi: 10.1177/2472555219880475.
Mark Soave 1 2 Barrie Kellam 2 3 Jeanette Woolard 1 2 Stephen J Briddon 1 2 Stephen J Hill 1 2
Affiliations

Affiliations

  • 1 Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham Medical School, Queen's Medical Centre, Nottingham, UK.
  • 2 Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands, UK.
  • 3 School of Pharmacy, Centre for Biomolecular Sciences, University of Nottingham, Nottingham, UK.
Abstract

Receptor internalization in response to prolonged agonist treatment is an important regulator of G protein-coupled receptor (GPCR) function. The adenosine A1 receptor (A1AR) is one of the Adenosine Receptor family of GPCRs, and evidence for its agonist-induced internalization is equivocal. The recently developed NanoBiT technology uses split NanoLuc Luciferase to monitor changes in protein interactions. We have modified the human A1AR on the N-terminus with the small high-affinity HiBiT tag. In the presence of the large NanoLuc subunit (LgBiT), complementation occurs, reconstituting a full-length functional NanoLuc Luciferase. Here, we have used complemented luminescence to monitor the internalization of the A1AR in living HEK293 cells. Agonist treatment resulted in a robust decrease in cell-surface luminescence, indicating an increase in A1AR internalization. These responses were inhibited by the A1AR-selective antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX), with an antagonist affinity that closely matched that measured using ligand binding with a fluorescent A1 receptor antagonist (CA200645). The agonist potencies for inducing A1AR internalization were very similar to the affinities previously determined by ligand binding, suggesting little or no amplification of the internalization response. By complementing the HiBiT tag to exogenous purified LgBiT, it was also possible to perform NanoBRET ligand-binding experiments using HiBiT-A1AR. This study demonstrates the use of NanoBiT technology to monitor internalization of the A1AR and offers the potential to combine these experiments with NanoBRET ligand-binding assays.

Keywords

GPCR; NanoBiT; adenosine; nanoluciferase complementation; receptor internalization.

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