The β(2)-adrenergic receptor (β(2)AR) agonists with reduced tachyphylaxis may offer new therapeutic agents with improved tolerance profile. However, receptor desensitization assays are often inferred at the single signaling molecule level, thus ligand-directed desensitization is poorly understood. Here we report a label-free biosensor whole cell assay with microfluidics to determine ligand-directed desensitization of the β(2)AR. Together with mechanistic deconvolution using small molecule inhibitors, the receptor desensitization and resensitization patterns under the short-term agonist exposure manifested the long-acting agonism of salmeterol, and differentiated the mechanisms of agonist-directed desensitization between a full agonist epinephrine and a partial agonist pindolol. This study reveals the cellular mechanisms of agonist-selective β(2)AR desensitization at the whole cell level.
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Adv Pharmacol
December 2017
PharmNovo UK Ltd. and School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool, United Kingdom. Electronic address:
It is now clear that, in contrast to traditional descriptions of G protein-coupled receptor signaling, agonists can activate or inhibit characteristic patterns of downstream effector pathways depending on their structures and the conformational changes induced in the receptor. This is referred to as functional selectivity (also known as agonist-directed trafficking, ligand-induced differential signaling, or biased agonism). It is important because even small structural differences can result in significant variations in overall agonist effects (wanted and unwanted) depending on which postreceptor signaling systems are engaged by each agonist/receptor pairing.
View Article and Find Full Text PDFCurr Pharm Des
September 2014
Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, H-6701 Szeged, P.O. Box 521, Hungary.
Here we have studied regulatory changes of µ-opioid receptors accompanying in vivo 14-methoxymetopon treatments of rats. Previously, this ligand has been shown to be an extremely potent, centrally acting µ-opioid specific analgesic with low physical dependence, tolerance, respiratory depression, constipation and other side effects. Our work shows that it is a highly potent full agonist of µ-opioid receptor coupled G-protein signaling in vitro, alike the well-known opioid agonist, etorphine.
View Article and Find Full Text PDFMol Pharmacol
April 2013
Department of Pharmacology, Instituto de Biociências, Universidade Estadual Paulista (UNESP), Botucatu, São Paulo, Brazil.
Loss of response on repetitive drug exposure (i.e., tachyphylaxis) is a particular problem for the vasoconstrictor effects of medications containing oxymetazoline (OXY), an α1-adrenoceptor (AR) agonist of the imidazoline class.
View Article and Find Full Text PDFPLoS One
April 2011
Biochemical Technologies, Science and Technology Division, Corning Inc., Corning, New York, United States of America.
The β(2)-adrenergic receptor (β(2)AR) agonists with reduced tachyphylaxis may offer new therapeutic agents with improved tolerance profile. However, receptor desensitization assays are often inferred at the single signaling molecule level, thus ligand-directed desensitization is poorly understood. Here we report a label-free biosensor whole cell assay with microfluidics to determine ligand-directed desensitization of the β(2)AR.
View Article and Find Full Text PDFPlatelets
September 2004
Department of Anesthesiology, Mount Sinai School of Medicine, New York, NY 10029, USA.
Platelet shape change (SC), aggregation and deaggregation responses are integral components of hemostasis that are elicited and modulated in vivo by the simultaneous activation of several membrane receptors. Selective activation of the purinergic P2Y1 receptor in vivo elicits a sustained SC and a small, transient aggregation response that is reversed rapidly by a robust deaggregation response (Platelets 2003; 14: 89). Using a kinetics-based turbidimetric approach to study the modulation of these concurrent components of human platelet responses, we demonstrate that these P2Y1 receptor-related responses and a number of their kinetic and steady-state characteristics are differentially elicited and modulated.
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