Abstract
G protein-coupled receptors (GPCRs) can interact with both G proteins and β-arrestin proteins to propagate different signaling outputs. In some contexts, agonists may drive the receptor to preferentially engage one of these effectors over the other. Such “ligand bias” may present a means to impart pathway-selective signaling downstream of this class of receptors. In cases where physiological responses are mediated by diverse pathways, this could, in part, provide a means to refine GPCR therapeutics. Cell-based signaling assays are used to measure the potential for signaling bias in vitro, and these measures take into account potency, efficacy, and the overall capacity of the assay. However, narrow assay windows sometimes limit the confidence in estimating agonist activity, if a compound performs as a very weakly efficacious partial agonist. This lack of response in an assay hampers the ability to measure and compare potencies, and the degree of separation of an agonist’s performance, between two assays. In this chapter, we describe in detail a method for the estimation of the relative activity of a partial agonist and provide a stepwise protocol for calculating bias when this case arises.
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References
DeWire SM, Seungkirl A, Lefkowitz RJ, Shenoy SK (2007) β-Arrestins and cell signaling. Annu Rev Physiol 69:483–510
Ehlert FJ (2007) On the analysis of ligand directed signaling at G protein coupled receptors. NS Arch Pharmacol 377:549–577
Ehlert FJ, Griffin MT, Suga H (2011) Analysis of functional responses at G protein-coupled receptors: estimation of relative affinity constants for the inactive receptor state. JPET 338(2):658–670
Kenakin T, Watson C, Muniz-Medina V, Christopoulos A, Novick S (2012) A simple method for quantifying functional selectivity and agonist Bias. ACS Chem Neurosci 3(3):193–203
Arunlakshana O, Schild HO (1959) Some quantitative uses of drug antagonists. Br J Pharmacol 48(14):48–58
Gaddum JH (1937) The quantitative effects of antagonistic drugs. J Physiol 89:7P–9P
Barlow RB, Scott NC, Stephenson RP (1967) The affinity and efficacy of onium salts on the frog rectus abdominis. Br J Pharmacol Chemother 31(1):188–196
Black JW, Leff P (1983) Operational models of pharmacological agonism. Proc R Soc Lond B Biol Sci 220(1219):141–162
Stahl EL, Zhou L, Ehlert FJ, Bohn LM (2015) A novel method for analyzing extremely biased agonism at G protein–coupled receptors. Mol Pharmacol 87(5):866–877
van der Westhuizen ET, Breton B, Christopoulos A, Bouvier M (2014) Quantification of ligand bias for clinically relevant beta2-adrenergic receptor ligands: implications for drug taxonomy. Mol Pharmacol 85(3):492–509
“Entering a user-defined model into Prism.” GraphPad Software, Inc. http://www.graphpad.com/guides/prism/6/curve-fitting/index.htm?reg_writing_models.htm. Accessed 1 May 2016.
Kenakin T, Christopoulos A (2013) Signalling bias in new drug discovery: detection, quantification and therapeutic impact. Nat Rev Drug Discov 12(3):205–216
Luttrell L, Kenakin T (2011) Refining efficacy: allosterism and bias in G protein-coupled receptor signaling. In: Luttrell L, Fergson S (eds) Signal transduction protocols, methods in molecular biology, vol vol. 756. Humana Press, Totowa, NJ
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Stahl, E.L., Ehlert, F.J., Bohn, L.M. (2019). Quantitating Ligand Bias Using the Competitive Model of Ligand Activity. In: Scott, M., Laporte, S. (eds) Beta-Arrestins. Methods in Molecular Biology, vol 1957. Humana Press, New York, NY. https://doi.org/10.1007/978-1-4939-9158-7_15
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DOI: https://doi.org/10.1007/978-1-4939-9158-7_15
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