X-linked congenital nephrogenic diabetes insipidus (cNDI) results from inactivating mutations of the human arginine vasopressin (AVP) V2 receptor (hV 2 R). Most of these mutations lead to intracellular retention of the hV 2 R, preventing its interaction with AVP and thereby limiting water reabsorption and concentration of urine. Because the majority of cNDI-hV 2 Rs exhibit protein misfolding, molecular chaperones hold promise as therapeutic agents; therefore, we sought to identify pharmacochaperones for hV 2 R that also acted as agonists. Here, we describe high-affinity nonpeptide compounds that promoted maturation and membrane rescue of L44P, A294P, and R337X cNDI mutants and restored a functional AVP-dependent cAMP signal. Contrary to pharmacochaperone antagonists, these compounds directly activated a cAMP signal upon binding to several cNDI mutants. In addition, these molecules displayed original functionally selective properties (biased agonism) toward the hV 2 R, being unable to recruit arrestin, trigger receptor internalization, or stimulate mitogen-activated protein kinases. These characteristics make these hV 2 R agonist pharmacochaperones promising therapeutic candidates for cNDI. The antidiuretic hormone arginine-vasopressin (AVP) is crucial for osmoregulation, cardiovascular control, and water homeostasis. The human AVP V 2 receptor (hV 2 R), localized in the principal cells of the kidney collecting duct, mediates AVP antidiuretic effect and therefore helps in maintaining physiologic plasma osmolality, blood volume, and arterial pressure. Binding of AVP to hV 2 R first triggers a cAMP signal through activation of the G protein ␣ s (Gs) subunit and adenylyl cyclase (AC). Then, the cAMP-activated protein kinase A phosphorylates aquaporin 2 water channels, resulting in their insertion into the luminal membrane of principal cells and finally to water reabsorption. 1 AVP binding to hV 2 R also induces arrestin recruitment, receptor internalization, 2 and mitogen-activated protein kinase (MAPK) activation. 3 Mutations in the hV 2 R gene lead to the X-linked congenital nephrogenic diabetes insipidus (cNDI), a rare disease characterized by the kidney's inability to concentrate urine despite normal or elevated plasma concentrations of AVP. 4 More than 200 different mutations have been described and are responsible for polyuria, a main consequence of the disease. Most of the mutant receptors (cNDIhV 2 Rs), trapped in the endoplasmic reticulum

A series of fluorescent benzazepine ligands for the arginine-vasopressin V₂ receptor (AVP V₂R) was synthesized using "Click" chemistry. Their in vitro pharmacological profile at AVP V₂R, V(1a)R, V(1b)R, and oxytocin receptor was measured by binding assay and functional studies. Compound 9p, labeled with Lissamine Rhodamine B using novel solid-phase organic tagging (SPOrT) resin, exhibited a high affinity for V₂R (4.0 nM), an excellent selectivity toward V₂R and antagonist properties. By changing the nature of the dye, DY647 and Lumi4-Tb probes 44 and 47 still display a high affinity for V₂R (5.6 and 5.8 nM, respectively). These antagonists constitute the first high-affinity selective nonpeptidic fluorescent ligands for V₂R. They enabled the development of V₂R time-resolved FRET-based assay readily amenable to high-throughput screening. Taking advantage of their selectivity, these compounds were also successfully involved in the study of V(1a)R-V₂R dimerization on cell surface.

Oxytocin (OT) and its receptor (OT-R) are implicated in the etiology of autism spectrum disorders (ASD), and OT-R is a potential target for therapeutic intervention. Very few nonpeptide oxytocin agonists have currently been reported. Their molecular and in vivo pharmacology remain to be clarified, and none of them has been shown to be efficient in improving social interaction in animal models relevant to ASD. In an attempt to rationalize the design of centrally active nonpeptide full agonists, we studied in a systematic way the structural determinants of the affinity and efficacy of representative ligands of the V and V vasopressin receptor subtypes (V-R and V-R) and of the oxytocin receptor. Our results confirm the subtlety of the structure-affinity and structure-efficacy relationships around vasopressin/oxytocin receptor ligands and lead however to the first nonpeptide OT receptor agonist active in a mouse model of ASD after peripheral ip administration.