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Br J Pharmacol. 2013 Feb;168(4):807-21. doi: 10.1111/j.1476-5381.2012.02217.x.

Discovery of new antagonists aimed at discriminating UII and URP-mediated biological activities: insight into UII and URP receptor activation.

Author information

1
Laboratoire d'études moléculaires et pharmacologiques des peptides, Université du Québec, INRS-Institut Armand-Frappier, Ville de Laval, QC, Canada. david.chatenet@iaf.inrs.ca

Abstract

BACKGROUND AND PURPOSE:

Recent evidence suggested that urotensin II (UII) and its paralog peptide UII-related peptide (URP) might exert common but also divergent physiological actions. Unfortunately, none of the existing antagonists were designed to discriminate specific UII- or URP-associated actions, and our understanding, on how these two endogenous peptides can trigger different, but also common responses, is limited.

EXPERIMENTAL APPROACH:

Ex vivo rat and monkey aortic ring contraction as well as dissociation kinetics studies using transfected CHO cells expressing the human urotensin (UT) receptors were used in this study.

KEY RESULTS:

Ex vivo rat and monkey aortic ring contraction studies revealed the propensity of [Pep(4)]URP to decrease the maximal response of human UII (hUII) without any significant change in potency, whereas no effect was noticeable on the URP-induced vasoconstriction. Dissociation experiments demonstrated the ability of [Pep(4)]URP to increase the dissociation rate of hUII, but not URP. Surprisingly, URP, an equipotent UII paralog, was also able to accelerate the dissociation rate of membrane-bound (125)I-hUII, whereas hUII had no noticeable effect on URP dissociation kinetics. Further experiments suggested that an interaction between the glutamic residue at position 1 of hUII and the UT receptor seems to be critical to induce conformational changes associated with agonistic activation. Finally, we demonstrated that the N-terminal domain of the rat UII isoform was able to act as a specific antagonist of the URP-associated actions.

CONCLUSION:

Such compounds, that is [Pep(4)]URP and rUII(1-7), should prove to be useful as new pharmacological tools to decipher the specific role of UII and URP in vitro but also in vivo.

PMID:
22994258
PMCID:
PMC3631372
DOI:
10.1111/j.1476-5381.2012.02217.x
[Indexed for MEDLINE]
Free PMC Article

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