Cryptorchism: a multidisciplinary approach

peer reviewe

Développement de ligands originaux pour SUCNR1

G protein coupled receptors (GPCR) are the largest family of membrane receptors and currently the most successfully targeted protein for therapeutic purposes. However, many remain uncharacterized. For example, the succinate receptor 1 (SUCNR1, previously termed GPR91) and its endogenous ligand have been described as "metabolism sensor" because succinate (SA) is a citric acid cycle intermediate that is released outside the cell in case of oxygen deprivation. A lot of studies have addressed the roles of SUCNR1 and demonstrated its implication in the enhancement of immunity, retinal angiogenesis, hypertension. Collectively, these data suggest that SUCNR1 could be an attractive drug target in several pathologies. However, no synthetic agonists and very few ligands have been described. Therefore, there is a crucial need for small molecule tools in order to study its function and validate this receptor as a drug target The objective of our project is to design, synthesize and characterize synthetic ligands for this receptor. Several diversified strategies have been envisaged accordingly. These include exploration of structure-activity relationships by means of organic synthesis or screening of virtual and chemical libraries. First, we have established an original screening methodology for Gi coupled receptors such as SUCNR1. Following the screening of a home-made library of succinic acid related molecules, we have established a pharmacophore that led to the identification of first original and synthetic SUCNR1 agonists. In addition, we constructed a model for the SUCNR1 binding site by homology modeling. This model will subsequently serve for a virtual screen of the ZINC database by docking. We plan to screen our collection of 50.000 molecules from a Diversity Oriented Strategy (DOS) library. This exploratory step will diversify the active chemical scaffolds and their pharmacological profiles.Identification, synthesis and design of original ligands for orphan GPC

Forskolin-free cAMP assay for Gi-coupled receptors

peer reviewe

Identidication, conception et évaluation d'outils pharmacologiques pour RCPG orphelin GPR22

GPCRs are the largest family of membrane receptors and are characterized by seven transmembrane domains. This family of receptors is currently the most successfully targeted protein for therapeutic purposes. GPR22 is a GPCR that was discovered in 1997. It has no known endogenous ligand and is thus considered "orphan". Its presence situated at the heart and brain levels makes it a potential target for new therapeutic pathways. The only information about its signaling channel could be its coupling with G proteins. This study consist in the identification of a synthetic ligand of GPR22 receptor to use it as a pharmacological tool in the study of the signaling channels of GPR22 in order to understand its role and to validate it as a new therapeutic target. The initial hypothesis was that GPR22 is coupled to the Gαi protein

GPR101 orphan GPCR: a novel cause of growth hormone deregulation

GPR101 is an orphan G-protein coupled receptor with unknown ligand. In 2014, an international study clearly pointed to a strong association between this receptor and the X-linked acrogigantism (X-LAG) syndrome, which begins in childhood and causes the “tallest giants”. The children (carriers of the GPR101 duplication on the X chromosome) grow abnormally even before they are one year old, secrete phenomenal quantities of growth hormone, and develop pituitary adenomas that do not respond to current therapies. The mechanism by which GPR101 contributes to increased growth hormone secretion is currently not known. Nevertheless, the lack of mechanistic insight into the function of GPR101 precludes its validation as a drug target. This lack of knowledge on GPR101 is the consequence of the paucity of specific pharmacological/research tools currently available. Therefore, we propose to study GPR101 functions and its role in growth hormone regulation. First, we determined the receptor cellular localization. We also deciphered its constitutive signalling pathways by detecting high cAMP levels. We completed our study with an examination of receptor coupling to other pathways and G proteins. Furthermore, we applied targeted mutagenesis to modulate the receptor constitutive activity in order to understand the receptor function at a molecular level. These GPR101 mutants will help us to understand the role of this receptor in GH regulation and/or to treat people suffering from pituitary dysfunction. This information is an absolute prerequisite to link molecular pharmacology of GPR101 with physiological functions.GPR101 orphan receptor: a novel cause of growth hormone deregulatio

design de ligand hautement afin pour le cite allostérique des benzothiadiazine des récepteur AMPA

L-glutamic acid is the major excitatory neurotransmitter in the brain. It exerts its effects through metabotropic and ionotropic receptors. Among the latter, three subtypes have been identified: NMDA, AMPA and KA receptors. It is now well established that a deficit in glutamatergic signaling may be responsible for neurological disorders such as mild cognitive impairment, schizophrenia, depression, and ADHD. Enhancement of the signal through positive allosteric modulators of AMPA receptors might be a therapeutic issue for these diseases. These compounds are expected to exert a fine tuning of the signal. Since they require the presence of the endogenous ligand to be active, they are expected to induce less toxicity than agonists. In this context, based on the structure of known allosteric modulators of AMPA receptors such as cyclothiazide and IDRA 21, the Laboratory of Medicinal Chemistry (University of Liège) has developed a series of 1,2,4-benzothiadiazine 1,1-dioxides with high potency as AMPA receptor potentiators. Crystallographic data obtained by the Department of Drug Design and Pharmacology (University of Copenhagen) highlighted those potentiators bind to two contiguous sites at the dimer interface of the ligand binding domain (LBD) of the AMPA receptor1,2. Based on these data, we may expect that the synthesis of dimeric molecules could lead to further improvement in affinity and activity. This assumption was reinforced by docking experiments conducted with virtual examples of dimeric compounds on the GluA2-LBD (collaboration with NAMEDIC). The present work is thus focusing on the preparation of a family of dimeric benzothiadiazine dioxides. Moreover, in collaboration with GIGA-Molecular Pharmacology, we are developing a pharmacological in vitro assay based on the measurement of Ca2+ inflow through a fluorimetric method. This medium-throughput screening will enable the characterization of our new compounds and the validation of our working hypothesis.Design, synthesis and pharmacological evaluation of dimeric ligands for the benzothiadiazine dioxide allosteric binding site of the AMPA receptor