Biology subjects

Orcel, H.

Publications and source records attributed to Orcel, H..

4 recordsLinked to original sources

bioRxiv2024

Inactive structures of the vasopressin V2 receptor reveal distinct antagonist binding modes for Tolvaptan and Mambaquaretin toxin

AbstractAntagonists of the arginine-vasopressin (AVP) V2 receptor (V2R) are key therapeutic compounds to treat hyponatremia or polycystic kidney diseases. Compounds such as Tolvaptan (TVP) and Conivaptan are marketed drugs but their mechanisms of inhibition are not known. In addition, TVP presents unwanted side effects such as serious liver injury. Conivaptan also targets AVP V1a receptor subtype and thus is not selective to V2R. To develop novel molecules with less side effects and better selectivity, rational drug design based on experimental three-dimensional G protein-coupled receptor (GPCR) structures is a powerful and successful avenue. The lack of antagonist-bound V2R structures has however impaired this strategy for this GPCR. To fill this gap of knowledge, we solved here the cryo-electron microscopy structures of the vasopressin V2R in complex with two selective antagonists, the nonpeptide TVP and the green mamba snake Mambaquaretin toxin (MQ1). Both ligands, known to be competitive, bind into the orthosteric AVP binding site but with substantial differences. The small molecule binds deeper than MQ1, and directly contacts the toggle switch residue W2846.48 in the transmembrane domain 6 (TM6), whereas the peptide Kunitz- fold toxin presents more extensive contacts with the receptor through additional interactions with extracellular and transmembrane residues. As anticipated from the pharmacological properties of TVP and MQ1, both structures represent inactive conformations of the V2R. Their comparison with those of the active AVP-bound V2R reveals the molecular mechanisms modulating receptor activity. Finally, the structure of the V2R bound to a mini-protein such as MQ1 opens a new pharmacology era in the field of water homeostasis and renal diseases.

pharmacology and toxicology↗

bioRxiv2023

Biased activation of the vasopressin V2 receptor probed by NMR, paramagnetic ligands, and molecular dynamics simulations

G protein-coupled receptors (GPCRs) control critical intercellular communications by responding to extracellular stimuli and undertaking conformational changes to convey signals to intracellular effectors. We combined NMR, molecular pharmacology, and molecular dynamics (MD) simulations to study the conformational diversity of the vasopressin V2 GPCR subtype (V2R) bound to different types of ligands: the antagonist tolvaptan, the endogenous unbiased agonist arginine-vasopressin, and MCF14, a Gs-protein biased agonist. We developed a double-labeling NMR scheme to study the conformational dynamics: V2R was subjected to lysine 13CH3 methylation, whereas the agonists were tagged with a paramagnetic probe. Paramagnetic relaxation enhancements were used to validate the ligand binding poses in the MD simulations. We found that the bias for the Gs protein over the {beta}-arrestin pathway involves interactions between the conserved NPxxY motif in the transmembrane helix (TM) 7 and a central hydrophobic patch in TM3, which constrains TM7 and likely inhibits {beta}-arrestin signaling. A similar mechanism was observed for the pathogenic mutation, I1303.43N, which constitutively activates the Gs protein without concomitant {beta}-arrestin recruitment. This mechanism resembles to opioid receptors findings indicating common patterns in class A GPCRs.

biophysics↗

bioRxiv2022

Structure of the vasopressin hormone-V2 receptor-β-arrestin1 ternary complex

Arrestins interact with G protein-coupled receptors (GPCRs) to stop G protein activation and to initiate key signaling pathways. Recent structural studies shed light on the molecular mechanisms involved in GPCR-arrestin coupling, but whether this process is conserved among GPCRs is poorly understood. Here, we report the cryo-electron microscopy active structure of the wild-type arginine-vasopressin V2 receptor (V2R) in complex with {beta}-arrestin1. It reveals an atypical position of {beta}-arrestin1 compared to previously described GPCR-arrestin assemblies, associated with an original V2R/{beta}-arrestin1 interface involving all receptor intracellular loops. Phosphorylated sites of the V2R C-terminus are clearly identified and interact extensively with the {beta}-arrestin1 N-lobe, in agreement with structural data obtained with chimeric or synthetic systems. Overall, these findings highlight a striking structural variability among GPCR-arrestin signaling complexes.

biochemistry↗

bioRxiv2020

Structure of the antidiuretic hormone vasopressin receptor signalling complex.

Arginine-vasopressin (AVP) is a neurohypophysial peptide known as the antidiuretic hormone. It forms an active signalling complex with the V2 receptor (V2R) and the Gs protein, promoting a cAMP/PKA-dependent aquaporin insertion in apical membranes of principal cells of the renal collecting ducts and ultimately, water reabsorption. Molecular mechanisms underlying activation of this critical G protein-coupled receptor (GPCR) signalling system are still unknown. To fill this gap of knowledge, we report here the structure of the AVP-V2R-Gs complex using cryo-electron microscopy (cryo-EM). Single-particle analysis revealed the presence of three different states. The two best maps were combined with computational and NMR spectroscopy constraints to reconstruct two structures of the ternary complex. These structures differ in AVP and Gs binding modes and could thus represent distinct complex conformations along the signalling activation pathway. Importantly, as compared to those of other class A GPCR-Gs complexes, the structures revealed an original receptor-Gs interface in which the Gs subunit penetrates deeper into the active V2R, notably forming an ionic bond between its free C-terminal carboxylic function and the side chain of R137 in the V2R. Interestingly, the structures help to explain how V2R R137H or R137L/C variants can lead to two severe genetic diseases with opposite clinical outcomes, cNDI or NSIAD respectively. Our study thus provides important structural insights into the function of this clinically relevant GPCR signalling complex.

biochemistry↗