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Biased agonism reveals new G protein‐independent AT1a receptor signals
Author(s) -
Kendall Ryan Thomas,
Lee MiHye,
ElShewy Hesham M.,
Janech Michael G.,
Luttrell Deirdre K.,
Luttrell Louis M.
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.880.5
Subject(s) - gq alpha subunit , heterotrimeric g protein , microbiology and biotechnology , phosphorylation , receptor , hek 293 cells , autocrine signalling , prostaglandin e2 receptor , chemistry , signal transduction , g protein coupled receptor , agonist , g protein , biology , biochemistry
The angiotensin II analog [Sar 1 , Ile 4 , Ile 8 ]AngII (SII) is a biased AT1a receptor agonist that stimulates receptor phosphorylation, βarrestin recruitment, internalization and βarrestin‐dependent ERK1/2 activation‐without activating heterotrimeric G proteins. To determine the scope of G protein‐independent AT1a receptor signaling, we performed a phosphoproteomic analysis of SII‐induced signaling in HEK cells stably expressing AT1a receptors. A total of 26 differentially abundant proteins were analyzed by phosphostaining 2D gels and identified by peptide mass fingerprinting. Phosphorylation of two peptide inhibitors of protein phosphatase 2A (I1PP2A and I2PP2A), prostaglandin E synthase 3 (PGES3) and casein kinase (CK2β) was confirmed by immunoprecipitation and immunoblotting with phospho‐specific probes. Functionally, SII stimulation produced rapid and transient inhibition of PP2A activity in HEK cells and stimulated PGE 2 synthesis in primary vascular smooth muscle. These findings suggest that AT1a receptors regulate a robust G protein‐independent signaling network that affects protein phosphorylation and autocrine/paracrine prostaglandin production, and that these pathways can be selectively modulated by biased ligands that antagonize G protein activation. This work was supported by NIH grants HL07260 (R.T.K.) and DK55524 (L.M.L.) and a Department of Veterans Affairs REAP Awards.