Heteromerization of angiotensin receptors changes trafficking and arrestin recruitment profiles

• Published in: Cellular signalling 2011-11, Vol.23 (11), p.1767-1776
• Main Authors: Porrello, Enzo R., Pfleger, Kevin D.G., Seeber, Ruth M., Qian, Hongwei, Oro, Cristina, Abogadie, Fe, Delbridge, Lea M.D., Thomas, Walter G.
• Format: Article
• Language: English
• Subjects: Angiotensin II - metabolism; Angiotensin II - pharmacology; Arrestins - metabolism; Arrestins - pharmacology; AT 1 receptor; AT 2 receptor; Biological Assay; Cell Membrane - metabolism; Cell Movement; Fluorescence; GPCR-HIT; HEK293 Cells; Heteromerization; Homomerization; Humans; Ligands; Microscopy, Confocal; Peptide Fragments - analysis; Peptide Fragments - chemistry; Phosphorylation; Plasmids; Polymerization; Protein Binding; Protein-fragment complementation assay; Receptor Cross-Talk - drug effects; Receptor, Angiotensin, Type 1 - genetics; Receptor, Angiotensin, Type 1 - metabolism; Receptor, Angiotensin, Type 2 - genetics; Receptor, Angiotensin, Type 2 - metabolism; Renin-Angiotensin System - physiology; Sensitivity and Specificity; Transfection
• ISSN: 0898-6568; 1873-3913
• DOI: 10.1016/j.cellsig.2011.06.011

The cardiovascular hormone angiotensin II (AngII) exerts its actions via two G protein-coupled receptor (GPCR) subtypes, AT 1 and AT 2, which often display antagonistic functions. Methodological constraints have so far precluded detailed analyses of the ligand-dependency, cellular localization, and functional relevance of AngII receptor interactions in live cells. In this study, we utilize a protein-fragment complementation assay (PCA) and GPCR-Heteromer Identification Technology (GPCR-HIT) to provide the first detailed investigation of the ligand-dependency and cellular localization of AngII receptor interactions in human embryonic kidney 293 cells. Fluorescent-tagged receptor constructs for PCA and GPCR-HIT displayed normal affinity and selectivity for AngII (AT 1: IC 50 = 1.0–1.6 nM; AT 2: IC 50 = 2.0–3.0 nM). Well-characterized angiotensin receptor interactions were used as positive and negative controls to demonstrate the sensitivity and specificity of these fluorescence-based assays. We report that AT 1–AT 2 receptor heteromers form constitutively, are localized to the plasma membrane and perinuclear compartments, and do not internalize following AngII stimulation despite arrestin being recruited specifically to the heteromer. Our findings using novel fluorescence-based technologies reveal a previously unrecognized mechanism of angiotensin receptor cross-talk involving cross-inhibition of AT 1 receptor internalization through heteromerization with the AT 2 receptor subtype. ► Novel fluorescence-based assays for studying angiotensin receptor interactions. ► AT 1 and AT 2 receptors form constitutive homo- and heteromers. ► AT 2 receptor cross-inhibits AT 1 receptor internalization. ► AT 2 –AT 1 heteromers do not co-internalize, despite b-Arrestin recruitment to dimer.