AT1R (angiotensin type 1 receptor) and AT2R (angiotensin type 2 receptor) are well known to be involved in the complex cardiovascular actions of AngII (angiotensin II). However, shorter peptide fragments of AngII are thought to have biological activity in their own right and elicit effects that oppose those mediated by AngII. In the present study, we have used HEK (human embryonic kidney)-293 cells stably transfected with either AT1R or AT2R to perform a systematic analysis of binding affinities of all the major angiotensin peptides. Additionally, we tested the novel AT2R agonist Compound 21, as well as the MasR (Mas receptor) agonist and antagonist AVE0991 and A-779 respectively, for their ability to bind to AT1R or AT2R. Candesartan, CGP42214 and PD123319 were used as reference compounds. Binding studies using 125I-[Sar1Ile8]AngII on the AT1R-transfected HEK-293 cells revealed only AngII, AngIII [angiotensin III; angiotensin-(2–8)] and candesartan to have high affinity for AT1R. In the AT2R-transfected HEK-293 cells, competition for 125I-[Sar1Ile8]AngII binding was observed for all ligands except candesartan, AVE0991 and A-779, the latter two compounds having negligible affinity at either AT1R or AT2R. The rank order of affinity of ligands at AT2R was CGP42112>AngII≥AngIII>Compound 21≥PD123319≫AngIV [angiotensin IV; angiotensin-(3–8)]>Ang-(1–7) [angiotensin-(1–7)]. Of note, although AngIV and Ang-(1–7) exhibited only modest affinity at AT2R compared with AngII, these two angiotensin peptides, together with AngIII, had substantial AT2R selectivity over AT1R. Collectively, our results suggest that shorter angiotensin peptides can act as endogenous ligands at AT2R.
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Research Article|
June 07 2011
Relative affinity of angiotensin peptides and novel ligands at AT1 and AT2 receptors
Sanja Bosnyak;
Sanja Bosnyak
*Department of Pharmacology, Monash University, Clayton, VIC 3800, Australia
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Emma S. Jones;
Emma S. Jones
*Department of Pharmacology, Monash University, Clayton, VIC 3800, Australia
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Arthur Christopoulos;
Arthur Christopoulos
*Department of Pharmacology, Monash University, Clayton, VIC 3800, Australia
†Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
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Marie-Isabel Aguilar;
Marie-Isabel Aguilar
‡Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia
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Walter G. Thomas;
Walter G. Thomas
§School of Biomedical Sciences, University of Queensland, Brisbane, QLD 4072, Australia
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Robert E. Widdop
*Department of Pharmacology, Monash University, Clayton, VIC 3800, Australia
Correspondence: Professor Robert E. Widdop (email [email protected]).
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Publisher: Portland Press Ltd
Received:
January 25 2011
Revision Received:
April 11 2011
Accepted:
May 04 2011
Accepted Manuscript online:
May 04 2011
Online ISSN: 1470-8736
Print ISSN: 0143-5221
© The Authors Journal compilation © 2011 Biochemical Society
2011
Clin Sci (Lond) (2011) 121 (7): 297–303.
Article history
Received:
January 25 2011
Revision Received:
April 11 2011
Accepted:
May 04 2011
Accepted Manuscript online:
May 04 2011
Connected Content
A commentary has been published:
Angiotensin Receptors - Affinity and Beyond
Citation
Sanja Bosnyak, Emma S. Jones, Arthur Christopoulos, Marie-Isabel Aguilar, Walter G. Thomas, Robert E. Widdop; Relative affinity of angiotensin peptides and novel ligands at AT1 and AT2 receptors. Clin Sci (Lond) 1 October 2011; 121 (7): 297–303. doi: https://doi.org/10.1042/CS20110036
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