Développement d'agonistes et d'antagonistes du récepteur de l'apéline – APELINE

Our efforts to clone an angiotensin III receptor led to the cloning of a gene encoding a rat seven transmembrane domain receptor exhibiting 95% sequence identity with that of the human orphan APJ receptor. The ligand for this receptor was identified en 1998 and and was named apelin. We characterized this receptor pharmacologically and we then demonstrated that apelin and its receptor were expressed together with vasopressin (AVP) in the magnocellular hypothalamic neurons. We showed that the central injection of apelin in lactating rats decreased the electrical activity of these neurons and the secretion of AVP into the bloodstream, resulting in aqueous diuresis. Finally, in rats and humans, apelin and AVP were found to be regulated in opposite manners by osmotic stimuli, thereby participating to the maintenance of body fluid homeostasis. Apelin and its receptor are also present in the heart, kidney and blood vessels and the systemic injection of apelin decreases arterial blood pressure, improves cardiac contractility and reduces cardiac loading. Apelin may therefore be involved in controlling cardiovascular function. No non-peptide agonist or antagonist of the apelin receptor has been yet discovered. Our aim is to obtain such compounds, making it possible to explore the role played by this peptide further upstream in cardiovascular diseases and water retention and/or hyponatremic disorders. Our project aims to: 1) Investigate the structure-function relationships of apelin and its receptor by molecular modelling and site-directed mutagenesis studies allowing identification of the structural requirements for binding of apelin to its receptor and for the subsequent signaling pathways activation (Teams 1 and 3) 2) Optimize the first partial agonist E339-3D6 we have previously identified (1 patent) (Teams 2 and 1) 3) Perform Medium Throughput Screening of diverse and drug-like by FRET and to validate the hits by binding studies (Teams 2 and 1) 4) Design virtual small focalized and cation-containing libraries (Teams 2 and 3) 5) Perform 'in silico' screening of virtual libraries (Team 3) 6) Synthesize and to evaluate the affinity of the hits (selected from the in silico screening) by binding studies (Team 2 and 1) 7) Optimize the best hits obtained in the different screenings (Teams 2 and 1) 8) Determine the pharmacological profile of the selected compounds, in vitro, ex vivo and in vivo (Team 1) 9) Determine the aquaretic effect of apelin at the kidney level (Team 1) We hope to discover a non-peptide agonist of the apelin receptor, which could be used to treat heart failure by favouring diuresis and improving the contractile performance of the myocardium whilst decreasing left ventricular preload and afterload. We hope to discover a non-peptide agonist of the apelin receptor, which could be used to treat heart failure by favouring diuresis and improving the contractile performance of the myocardium whilst decreasing left ventricular preload and afterload.