Brulé C1, Perzo N2, Joubert JE3, Sainsily X4, Leduc R4, Castel H3, Prézeau L5
Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada. Institut de genomique Fonctionnelle (IGF), Montpellier, France.
FASEB J. 2014;28(12):5148-62.
Biased agonism by G-protein-coupled receptor ligands has opened up strategies for targeted physiological or therapeutic actions. We hypothesized that urotensin II (UII)-derived peptides displayed unexpected physiological effects because of such biased signaling on the UII human urotensin (hUT) receptor. We determined the coupling to G proteins and β-arrestins of the UII-activated hUT receptor expressed in HEK293 using bioluminescence resonance energy transfer (BRET) biosensors, as well as the production of IP1-3 and cAMP using homogenous time-resolved Forster resonance energy transfer (FRET) (HTRF)-based assays. The activated receptor coupled to Gi1, GoA, Gq, and G13, excluding Gs, and recruited β-arrestins 1 and 2. Integration of these pathways led to a 2-phase kinetic phosphorylation of ERK1/2 kinases. The tested peptides induced three different profiles: UII, urotensin-related peptide (URP), and UII4-11 displayed the full profile; [Orn(8)]UII and [Orn(5)]URP activated G proteins, although with pEC50s 5-10× higher, and did not or barely recruited β-arrestin; urantide also failed to recruit β-arrestin but displayed a reversed rank order for Gi and Gq vs. Go pEC50s (-8.79±0.20, -8.43±0.21, and -7.86±0.36, respectively, for urantide, -7.87±0.10, -7.23±0.27, and -8.55±0.19, respectively, for [Orn(5)]URP) and was a partial agonist of all G-protein pathways. Interestingly, the peptides differently modulated cell survival but similarly induced cell migration and adhesion. Thus, we demonstrate biased signaling between β-arrestin and G proteins, and between G-protein subtypes, which dictates the receptor's cellular responses.