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.

Specific targeting of the IL-23 receptor, using a novel small peptide noncompetitive antagonist, decreases the inflammatory response

“…This functional selectivity is made possible by ligands, which bind in ways that affect the dynamic conformation of the receptor to interact with its natural ligand and associated proteins needed to activate normal signaling pathways (16,35); hence, such ligands can alter signaling modalities (32,56,57), which may confer greater selectivity and reduce side effects (32) compared with orthosteric antagonists, which disable all functions triggered by the receptor. These features seem to apply to 2305 in line with recent work on other cytokine and noncytokine receptors (24,44,46,57,58).…”

ECL1i, d(LGTFLKC), a novel, small peptide that specifically inhibits CCL2‐dependent migration

“…If peptides that reproduce extracellular loop sequences that arise from regions remote from the binding site can interfere in receptor conformation and ligand affinity, they would be expected to exert noncompetitive antagonism. Recently, structure‐based drug design allowed the development of peptides that arise from extracellular loops of various receptors, such as PGF 2α R (19), CCR5 (20), V2R (21), β 2 ‐adrenoceptors (22), or IL‐1 (23), which exhibit noncompetitive antagonist effects.…”

Allosteric and Biased G Protein-Coupled Receptor Signaling Regulation: Potentials for New Therapeutics

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