SYNTHESE D'ISOSTERES PYRROLINIQUES DE LA RILMENIDINE ET DE LA CLONIDINE

AU COURS DE CE TRAVAIL, NOUS NOUS SOMMES ATTACHES A OBTENIR DES NOUVEAUX LIGANDS SELECTIFS DES RECEPTEURS DES IMIDAZOLINES PAR RAPPORT AUX SITES DE LIAISON DES IMIDAZOLINES DE SOUS-TYPE 2 ET AUX RECEPTEURS 2-ADRENERGIQUES. DE TELS LIGANDS SONT EN EFFET D'UNE GRANDE UTILITE D'UNE PART POUR LA CARACTERISATION DES RECEPTEURS DES IMIDAZOLINES ET L'ETUDE DE L'EFFET HYPOTENSEUR PROVOQUE PAR LES DROGUES IMIDAZOLINIQUES, MAIS AUSSI POUR OBTENIR DE NOUVEAUX PROTOTYPES D'AGENTS ANTIHYPERTENSEURS CENTRAUX. POUR OBTENIR CES LIGANDS SELECTIFS, NOUS AVONS SYNTHETISE DES ISOSTERES PYRROLINIQUES DES DEUX DROGUES DE REFERENCE QUE SONT LA RILMENIDINE ET LA CLONIDINE. CES SYNTHESES ONT NOTAMMENT CONDUIT A : - UNE SERIE D'ANALOGUES PYRROLINIQUES DE LA RILMENIDINE, SELECTIFS DES RECEPTEURS DES IMIDAZOLINES ET CAPABLES DE FAIRE BAISSER LA PRESSION ARTERIELLE APRES ADMINISTRATION CENTRALE. UN DE CES ANALOGUES, LE LNP 509, S'EST D'ORES ET DEJA AVERE TRES UTILE POUR L'ETUDE DE L'EFFET HYPOTENSEUR DES IMIDAZOLINES. - DEUX ANALOGUES PYRROLINIQUES DE LA CLONIDINE, ORIGINAUX ET HYPOTENSEURS APRES ADMINISTRATION SYSTEMIQUE (LES LNP 541 ET LNP 560) QUI CONSTITUENT DEUX NOUVEAUX PROTOTYPES D'AGENTS ANTIHYPERTENSEURS CENTRAUX. - L'OBTENTION D'UN LIGAND RADIOMARQUE (LNP 911) ET D'UN LIGAND DE PHOTOAFFINITE (LNP 906) TOUS DEUX TRES SELECTIFS ET POSSEDANT UNE AFFINITE SUBNANOMOLAIRE POUR LES RECEPTEURS D'INTERET. CES DEUX MOLECULES CONSTITUENT DEUX NOUVEAUX OUTILS POUR L'ETUDE DES RECEPTEURS DES IMIDAZOLINES.STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF

Amino-pyrrolidine tricarboxylic acids give new insight into group III metabotropic glutamate receptor activation mechanism.

Collaboration Société Faust PharmaceuticalsInternational audienceLike most class C G-protein-coupled receptors, metabotropic glutamate (mGlu) receptors possess a large extracellular domain where orthosteric ligands bind. Crystal structures revealed that this domain, called Venus FlyTrap (VFT), adopts a closed or open conformation upon agonist or antagonist binding, respectively. We have described amino-pyrrolidine tricarboxylic acids (APTCs), including (2S,4S)-4-amino-1-[(E)-3-carboxyacryloyl]pyrrolidine-2,4-dicarboxylic acid (FP0429), as new selective group III mGlu agonists. Whereas FP0429 is an almost full mGlu4 agonist, it is a weak and partial agonist of the closely related mGlu8 subtype. To get more insight into the activation mechanism of mGlu receptors, we aimed to elucidate why FP0429 behaves differently at these two highly homologous receptors by focusing on two residues within the binding site that differ between mGlu4 and mGlu8. Site-directed mutagenesis of Ser157 and Gly158 of mGlu4 into their mGlu8 homologs (Ala) turned FP0429 into a weak partial agonist. Conversely, introduction of Ser and Gly residues into mGlu8 increased FP0429 efficacy. Docking of FP0429 in mGlu4 VFT 3D model helped us characterize the role of each residue. Indeed, mGlu4 Ser157 seems to have an important role in FP0429 binding, whereas Gly158 may allow a deeper positioning of this agonist in the cavity of lobe I, thereby ensuring optimal interactions with lobe II residues in the fully closed state of the VFT. In contrast, the presence of a methyl group in mGlu8 (Ala instead of Gly) weakens the interactions with the lobe II residues. This probably results in a less stable or a partially closed form of the mGlu8 VFT, leading to partial receptor activation

EGFR signaling and pharmacology in oncology revealed with innovative BRET-based biosensors

Abstract Mutations of receptor tyrosine kinases (RTKs) are associated with the development of many cancers by modifying receptor signaling and contributing to drug resistance in clinical settings. We present enhanced bystander bioluminescence resonance energy transfer-based biosensors providing new insights into RTK biology and pharmacology critical for the development of more effective RTK-targeting drugs. Distinct SH2-specific effector biosensors allow for real-time and spatiotemporal monitoring of signal transduction pathways engaged upon RTK activation. Using EGFR as a model, we demonstrate the capacity of these biosensors to differentiate unique signaling signatures, with EGF and Epiregulin ligands displaying differences in efficacy, potency, and responses within different cellular compartments. We further demonstrate that EGFR single point mutations found in Glioblastoma or non-small cell lung cancer, impact the constitutive activity of EGFR and response to tyrosine kinase inhibitor. The BRET-based biosensors are compatible with microscopy, and more importantly characterize the next generation of therapeutics directed against RTKs

Effector membrane translocation biosensors reveal G protein and βarrestin coupling profiles of 100 therapeutically relevant GPCRs

The recognition that individual GPCRs can activate multiple signaling pathways has raised the possibility of developing drugs selectively targeting therapeutically relevant ones. This requires tools to determine which G proteins and βarrestins are activated by a given receptor. Here, we present a set of BRET sensors monitoring the activation of the 12 G protein subtypes based on the translocation of their effectors to the plasma membrane (EMTA). Unlike most of the existing detection systems, EMTA does not require modification of receptors or G proteins (except for G(s)). EMTA was found to be suitable for the detection of constitutive activity, inverse agonism, biased signaling and polypharmacology. Profiling of 100 therapeutically relevant human GPCRs resulted in 1500 pathway-specific concentration-response curves and revealed a great diversity of coupling profiles ranging from exquisite selectivity to broad promiscuity. Overall, this work describes unique resources for studying the complexities underlying GPCR signaling and pharmacology

Respective contributions of α-adrenergic and non-adrenergic mechanisms in the hypotensive effect of imidazoline-like drugs

1. The hypotensive effect of imidazoline-like drugs, such as clonidine, was first attributed to the exclusive stimulation of central α 2-adrenoceptors (α 2ARs). 2. However, a body of evidence suggests that non-adrenergic mechanisms may also account for this hypotension. 3. This work aims (i) to check whether imidazoline-like drugs with no α 2adrenergic agonist activity may alter blood pressure (BP) and (ii) to seek a possible interaction between such a drug and an α 2ARs agonist α-methylnoradrenaline (α-MNA). 4. We selected S23515 and S23757, two imidazoline-like drugs with negligible affinities and activities at α 2ARs but with high affinities for non-adrenergic imidazoline binding sites (IBS). 5. S23515 decreased BP dose-dependently (-27±5% maximal effect) when administered intracisternally (i.c.) to anaesthetized rabbits. The hypotension induced by S23515 (100 μg kg -1 i.c.) was prevented by S23757 (1 mg kg -1 i.c.) and efaroxan (10 μgkg -1 i.c.), while these compounds, devoid of haemodynamic action by themselves, did not alter the hypotensive effect of α-MNA (3 and 30 μg kg -1 i.c.). Moreover, the α 2ARs antagonist rauwolscine (3 μg kg -1 i.c.) did not prevent the effect of S23515. 6. Finally, whilst 3 μg kg -1 of S23515 or 0.5 μg kg -1 of α-MNA had weak hypotensive effects, the sequential i.c. administration of these two drugs induced a marked hypotension (-23±2%). 7. These results indicate that an imidazoline-like drug with no α 2-adrenergic properties lowers BP and interacts synergistically with an α 22ARs agonist.link_to_subscribed_fulltex

Discovery, Structure–Activity Relationship, and Antiparkinsonian Effect of a Potent and Brain-Penetrant Chemical Series of Positive Allosteric Modulators of Metabotropic Glutamate Receptor 4

The metabotropic glutamate receptor 4 (mGluR4) is an emerging target for the treatment of Parkinson’s disease (PD). However, since the discovery of its therapeutic potential, no ligand has been successfully developed enough to be tested in the clinic. In the present paper, we report for the first time the medicinal chemistry efforts conducted around the pharmacological tool (−)-PHCCC. This work led to the identification of compound <b>40</b>, a potent and selective mGluR4 positive allosteric modulator (PAM) with good water solubility and demonstrating consistent activity across validated preclinical rodent models of PD motor symptoms after intraperitoneal administration: haloperidol-induced catalepsy in mouse and the rat 6-hydroxydopamine (6-OHDA) lesion model. Moreover, we also describe the identification of compound <b>60</b> a close analogue of compound <b>40</b> with improved pharmacokinetic profile after oral administration. On the basis of its favorable and unique preclinical profile, compound <b>60</b> (PXT002331, now foliglurax) was nominated as a candidate for clinical development