Antibodies against G-protein coupled receptors: novel uses in screening and drug development

Abstract

Antibodies are components of the body's humoral immune system that are generated in response to foreign pathogens. Modern biomedical research has employed these very specific and efficient molecules designed by nature in the diagnosis of diseases, localization of gene products as well as in the rapid screening of targets for drug discovery and testing. In addition, the introduction of antibodies with fluorescent or enzymatic tags has significantly contributed to advances in imaging and microarray technology, which are revolutionizing disease research and the search for effective therapeutics. More recently antibodies have been used in the isolation of dimeric G protein-coupled receptor (GPCR) complexes. In this review, we discuss antibodies as powerful research tools for studying GPCRs, and their potential to be developed as drugs themselves.

Fig. 1. An assay to study allosteric modulation of GPCRs using conformation-sensitive antibodies

The modulation of receptor conformation upon dual occupancy of protomers in a heterodimer was probed using SK-N-SH cells endogenously expressing μ and CB₁ receptors. Cells (2 × 10⁵ cells/well) plated on poly-L-lysine treated 24-well plates, were treated with 1 μM DAMGO (μ receptor agonist) in the absence or presence of indicated concentrations of Hu-210 or WIN515,212-2 (CB1 receptor agonists), for 30 min at 37°C in 50 mM Tris-Cl, pH 7.5. Cells were quickly rinsed, fixed with ice-cold methanol and subjected to ELISA using conformation-sensitive antibodies to μ opioid receptors as described [14]. O.D. 490 nm values obtained with cells not exposed to any drugs were taken as 100%. Results are Mean ± SD of triplicate determinations from 3 independent experiments.