beta-Arrestin 1 and 2 stabilize the angiotensin II type I receptor in distinct high-affinity conformations

TY - JOUR

T1 - beta-Arrestin 1 and 2 stabilize the angiotensin II type I receptor in distinct high-affinity conformations

AU - Sanni, S J

AU - Hansen, J T

AU - Bonde, M M

AU - Speerschneider, T

AU - Christensen, Gitte Lund

AU - Munk, S

AU - Gammeltoft, S

PY - 2010/9

Y1 - 2010/9

N2 - Background and Purpose The angiotensin II type 1 (AT 1) receptor belongs to family A of 7 transmembrane (7TM) receptors. The receptor has important roles in the cardiovascular system and is commonly used as a drug target in cardiovascular diseases. Interaction of 7TM receptors with G proteins or β-arrestins often induces higher binding affinity for agonists. Here, we examined interactions between AT 1A receptors and β-arrestins to look for differences between the AT 1A receptor interaction with β-arrestin1 and β-arrestin2. Experimental Approach Ligand-induced interaction between AT 1A receptors and β-arrestins was measured by Bioluminescence Resonance Energy Transfer 2. AT 1A-β-arrestin1 and AT 1A-β-arrestin2 fusion proteins were cloned and tested for differences using immunocytochemistry, inositol phosphate hydrolysis and competition radioligand binding. Key Results Bioluminescence Resonance Energy Transfer 2 analysis showed that β-arrestin1 and 2 were recruited to AT 1A receptors with similar ligand potencies and efficacies. The AT 1A-β-arrestin fusion proteins showed attenuated G protein signalling and increased agonist binding affinity, while antagonist affinity was unchanged. Importantly, larger agonist affinity shifts were observed for AT 1A-β-arrestin2 than for AT 1A-β-arrestin1. CONCLUSION AND IMPLICATIONS β-Arrestin1 and 2 are recruited to AT 1A receptors with similar ligand pharmacology and stabilize AT 1A receptors in distinct high-affinity conformations. However, β-arrestin2 induces a receptor conformation with a higher agonist-binding affinity than β-arrestin1. Thus, this study demonstrates that β-arrestins interact with AT 1A receptors in different ways and suggest that AT 1 receptor biased agonists with the ability to recruit either of the β-arrestins selectively, would be possible to design.

AB - Background and Purpose The angiotensin II type 1 (AT 1) receptor belongs to family A of 7 transmembrane (7TM) receptors. The receptor has important roles in the cardiovascular system and is commonly used as a drug target in cardiovascular diseases. Interaction of 7TM receptors with G proteins or β-arrestins often induces higher binding affinity for agonists. Here, we examined interactions between AT 1A receptors and β-arrestins to look for differences between the AT 1A receptor interaction with β-arrestin1 and β-arrestin2. Experimental Approach Ligand-induced interaction between AT 1A receptors and β-arrestins was measured by Bioluminescence Resonance Energy Transfer 2. AT 1A-β-arrestin1 and AT 1A-β-arrestin2 fusion proteins were cloned and tested for differences using immunocytochemistry, inositol phosphate hydrolysis and competition radioligand binding. Key Results Bioluminescence Resonance Energy Transfer 2 analysis showed that β-arrestin1 and 2 were recruited to AT 1A receptors with similar ligand potencies and efficacies. The AT 1A-β-arrestin fusion proteins showed attenuated G protein signalling and increased agonist binding affinity, while antagonist affinity was unchanged. Importantly, larger agonist affinity shifts were observed for AT 1A-β-arrestin2 than for AT 1A-β-arrestin1. CONCLUSION AND IMPLICATIONS β-Arrestin1 and 2 are recruited to AT 1A receptors with similar ligand pharmacology and stabilize AT 1A receptors in distinct high-affinity conformations. However, β-arrestin2 induces a receptor conformation with a higher agonist-binding affinity than β-arrestin1. Thus, this study demonstrates that β-arrestins interact with AT 1A receptors in different ways and suggest that AT 1 receptor biased agonists with the ability to recruit either of the β-arrestins selectively, would be possible to design.

KW - Animals

KW - Arrestins

KW - Cell Line

KW - GTP-Binding Proteins

KW - Humans

KW - Protein Conformation

KW - Receptor, Angiotensin, Type 1

KW - Signal Transduction

U2 - 10.1111/j.1476-5381.2010.00875.x

DO - 10.1111/j.1476-5381.2010.00875.x

M3 - Journal article

C2 - 20718747

SN - 0007-1188

VL - 161

SP - 150

EP - 161

JO - British Journal of Pharmacology

JF - British Journal of Pharmacology

IS - 1

ER -