Article pubs.acs.org/jmc
Development and Pharmacological Characterization of Conformationally Constrained Urotensin II-Related Peptide Agonists David Chatenet,*,†,‡ Benjamin Folch,† Debby Feytens,§ Myriam Létourneau,†,‡ Dirk Tourwé,§ Nicolas Doucet,†,∥,⊥ and Alain Fournier†,‡ †
INRS-Institut Armand-Frappier, Institut national de la recherche scientifique, Université du Québec, Ville de Laval, Québec, QC H7V 1B7, Canada ‡ Laboratoire International Associé Samuel de Champlain, INSERM-INRS-Université de Rouen § Department of Organic Chemistry, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium ∥ Regroupement Québécois de Recherche sur la Fonction, la Structure et l’Ingénierie des Protéines, PROTEO, Québec, QC G1V 0A6, Canada ⊥ GRASP, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Bellini Pavillion, Room 453, 3649 Promenade Sir William Osler, Montréal, QC H3G 0B1, Canada ABSTRACT: Urotensin II (UII) and its paralog peptide, urotensin II-related peptide (URP), exert not only common but also divergent actions through the activation of UT, a specific membrane-bound receptor that belongs to the 1A G proteincoupled receptor subclass. In this study, we have designed and synthesized new URP analogues in which the intracyclic Trp residue was replaced with natural, unnatural, and constrained amino acids to determine important physicochemical features for receptor binding and activation. The biological data, highlighting the potent agonistic behavior of [Tiq4]URP and [Tpi4]URP, also suggest that the Trp residue, and more specifically the indole ring, is not critical for receptor interaction and could in fact be involved in the intramolecular stabilization of the bioactive conformation of URP. Finally, these analogues, which are intracyclic constrained URP-based agonists, could represent useful pharmacological tools for the study of the urotensinergic system.
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INTRODUCTION Despite currently available drug therapies, cardiovascular diseases remain one of the major causes of death in the Western world. Therefore, identification of additional targets such as a G protein-coupled receptor (GPCR) that may modulate such pathological states is of particular interest. Following its deorphanization, the urotensin II receptor (UT), initially termed sensory epithelium neuropeptide-like receptor or GPR14, has been studied for its involvement in cardiovascular homeostasis in patients in a healthly or disease state.1 The biological activities associated with UT activation are modulated by two endogenous ligands, i.e., urotensin II (UII) and urotensin II-related peptide (URP).2 While the Cterminal cyclic region of these two peptides is well conserved throughout species, the N-terminal part included substantial sequence variations (Table 1). The role of this system in disease states, and particularly in cardiovascular and pulmonary diseases, is mostly based on experimental evidence.3 Elevated levels of UII-like immunoreactivity were, for instance, observed in various cardiovascular and metabolic diseases.4,5 The following symptoms were © 2013 American Chemical Society
correlated with the various effects exerted by UII and/or URP on the cardiovascular system both acutely and chronically: vasoconstriction leading to hypertension,6 positive inotropic and chronotropic responses,7 salt and water retention possibly via a direct tubular action,8 accumulation of extracellular matrix material,9,10 especially collagen and fibronectin, formation of macrophage foam cells,11 and induction of cardiac and vascular hypertrophy.12 This system appears to be critically involved in the development and progression of diseases. Indeed, inhibition of this system with a peptide or nonpeptide antagonist has recently provided in human and rodents strong evidence of a role for this system in cardiovascular and pulmonary diseases.13−16 For instance, genetic manipulation of the urotensinergic system by deletion of UII following an apolipoprotein E knockout, a model of atherosclerosis, clearly attenuated the initiation and progression of the disease.16 Also, in monocrotaline-induced pulmonary arterial hypertension, UT antagonists potently alleviated the sequalae associated with the Received: July 29, 2013 Published: November 19, 2013 9612
dx.doi.org/10.1021/jm401153j | J. Med. Chem. 2013, 56, 9612−9622
Journal of Medicinal Chemistry
Article
Table 1. Comparison of the Primary Structures of Mammalian UII and URPa
a
Conserved amino acids in urotensin II and URP isoforms are colored blue (intracyclic residues) and green (hydrophobic residue). Amino acids adjacent to the cyclic core are colored red for UII isoforms (acidic residues) or orange for URP isoforms (hydrophobic amino acid) to highlight their different physicochemical properties. The cyclic region is shown within brackets. 10−5 >10−6 277 (162−477) 9 (5−15) 361 (261−499) 808 (514−1270) 60 (44−82) 29 (20−41) 29 (20−41) 10 (5−19) 21 (12−34) >10−5 88 (61−125) >10−5 >10−5 −e
aortic ring contraction pIC50
n
EC50 (nM)b
± ± ± ± ± ±
0.07 0.11 0.12 0.07 0.11 0.09
3 4 3 3 3 3
± ± ± ± ± ± ± ± ±
0.12 0.11 0.07 0.09 0.07 0.08 0.06 0.15 0.11
3 3 3 3 4 3 3 4 3 3 3 3 3 3
1 (0.4−3) 7 (3−17) 54 (17−165) 825 (676−1000) 506 (124−1150) >10−6 −e >10−6 >10−6 40 (10−164) >10−6 181 (99−332) 159 (68−371) 251 (126−501) 117 (75−184) 22 (13−36) 21 (9−46) >10−6 259 (121−551) −e −e −e
7.88 7.90 7.77 7.33 7.24 6.74
