title: VRQ397 (CRAVKY): a novel noncompetitive V2 receptor antagonist.
abstract: Vasopressin type 2 receptor (V2R) exhibits mostly important properties for hydroosmotic equilibrium and, to a lesser extent, on vasomotricity. Drugs currently acting on this receptor are analogs of the natural neuropeptide, arginine vasopressin (AVP), and hence are competitive ligands. Peptides that reproduce specific sequences of a given receptor have lately been reported to interfere with its action, and if such molecules arise from regions remote from the binding site they would be anticipated to exhibit noncompetitive antagonism, but this has yet to be shown for V2R. Six peptides reproducing juxtamembranous regions of V2R were designed and screened; the most effective peptide, cravky (labeled VRQ397), was characterized. VRQ397 was potent (IC(50) = 0.69 +/- 0.25 nM) and fully effective in inhibiting V2R-dependent physiological function, specifically desmopressin-L-desamino-8-arginine-vasopressin (DDAVP)-induced cremasteric vasorelaxation; this physiological functional assay was utilized to avoid overlooking interference of specific signaling events. A dose-response profile revealed a noncompetitive property of VRQ397; correspondingly, VRQ397 bound specifically to V2R-expressing cells could not displace its natural ligand, AVP, but modulated AVP binding kinetics (dissociation rate). Specificity of VRQ397 was further confirmed by its inability to bind to homologous V1 and oxytocin receptors and its inefficacy to alter responses to stimulation of these receptors. VRQ397 exhibited pharmacological permissiveness on V2R-induced signals, as it inhibited DDAVP-induced PGI(2) generation but not that of cAMP or recruitment of beta-arrestin2. Consistent with in vitro and ex vivo effects as a V2R antagonist, VRQ397 displayed anticipated in vivo aquaretic efficacy. We hereby describe the discovery of a first potent noncompetitive antagonist of V2R, which exhibits functional selectivity, in line with properties of a negative allosteric modulator.
authors.affiliation: Departments of Pediatrics and Pharmacology, Hôpital Ste Justine, Research Center, Montreal, QC, Canada.
authors.forename: L
authors.initials: L
authors.lastname: Rihakova
authors.forename: C
authors.initials: C
authors.lastname: Quiniou
authors.forename: F F
authors.initials: FF
authors.lastname: Hamdan
authors.forename: R
authors.initials: R
authors.lastname: Kaul
authors.forename: S
authors.initials: S
authors.lastname: Brault
authors.forename: X
authors.initials: X
authors.lastname: Hou
authors.forename: I
authors.initials: I
authors.lastname: Lahaie
authors.forename: P
authors.initials: P
authors.lastname: Sapieha
authors.forename: D
authors.initials: D
authors.lastname: Hamel
authors.forename: Z
authors.initials: Z
authors.lastname: Shao
authors.forename: F
authors.initials: F
authors.lastname: Gobeil
authors.forename: P
authors.initials: P
authors.lastname: Hardy
authors.forename: J-S
authors.initials: JS
authors.lastname: Joyal
authors.forename: H
authors.initials: H
authors.lastname: Nedev
authors.forename: F
authors.initials: F
authors.lastname: Duhamel
authors.forename: K
authors.initials: K
authors.lastname: Beauregard
authors.forename: N
authors.initials: N
authors.lastname: Heveker
authors.forename: H U
authors.initials: HU
authors.lastname: Saragovi
authors.forename: G
authors.initials: G
authors.lastname: Guillon
authors.forename: M
authors.initials: M
authors.lastname: Bouvier
authors.forename: W D
authors.initials: WD
authors.lastname: Lubell
authors.forename: S
authors.initials: S
authors.lastname: Chemtob
mesh_terms: D015121:6-Ketoprostaglandin F1 alpha / Q000378:metabolism; D000494:Allosteric Regulation; D000818:Animals; D065092:Antidiuretic Hormone Receptor Antagonists; D001127:Arginine Vasopressin / Q000378:metabolism; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D003894:Deamino Arginine Vasopressin / Q000378:metabolism; D004231:Diuresis / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D006727:Hormone Antagonists / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D008024:Ligands; D008297:Male; D051379:Mice; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism; D009215:Myometrium / Q000187:drug effects* / Q000378:metabolism; D009842:Oligopeptides / Q000378:metabolism / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017483:Receptors, Vasopressin / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection; D001743:Urinary Bladder / Q000187:drug effects* / Q000378:metabolism
chemical_list: D065092:Antidiuretic Hormone Receptor Antagonists; D006727:Hormone Antagonists; D008024:Ligands; D009842:Oligopeptides; D017483:Receptors, Vasopressin; D011993:Recombinant Fusion Proteins; C544122:VRQ397; D001127:Arginine Vasopressin; D015121:6-Ketoprostaglandin F1 alpha; D000242:Cyclic AMP; D003894:Deamino Arginine Vasopressin