Projet ANR-10-CESA-0004 – BISCOT : Développement et utilisation d’outils pour l’étude des interactions entre les récepteurs nucléaires et les perturbateurs endocriniens
Programme : Contaminants, Ecosystèmes, Santé (CES) 2010
Année de financement : 2010
Coordinateur du projet : Monsieur vincent CAVAILLES (INSTITUT NATIONAL DE LA SANTE ET DE LA RECHERCHE MEDICALE - ADR LANGUEDOC-ROUSSILLON - ADR 8)
Partenaires : Centre de Biochimie Structurale; Institut national de la santé et de la recherche médicale
Montant : 350000.0 euros
Durée : 36 mois
Résumé : Human nuclear hormone receptors (NHRs) are a family of 48 transcription factors, many of which have been shown to be activated by ligands. NHRs regulate cognate gene networks involved in key physiological functions such as cell growth and differentiation, development, homeostasis or metabolism. As a consequence, dysfunctions in NHR signaling (i.e. receptor mutation or inappropriate exposure to environmental pollutants) often leads to proliferative, reproductive, and metabolic diseases, including hormonal cancers, infertility, obesity, or diabetes. NHRs are modular proteins composed of several domains, most notably an N-terminal domain which harbors a ligand-independent activation function (AF-1), a central DNA-binding domain (DBD) and a C-terminal ligand-binding domain (LBD) hosting a ligand-dependent transcriptional activation function (AF-2). Ligand binding induces major structural alterations of the receptor LBDs leading to (i) destabilization of corepressor or chaperone interfaces, (ii) exposure of nuclear localization signals which allow nuclear translocation of cytoplasmic receptors (iii) DNA binding and recruitment of coactivators triggering gene transcription through chromatin remodeling and activation of the general transcription machinery. The crystal structures of many NHR LBDs have been determined, revealing a conserved core of 12 alpha-helices (H1 to H12) and a short two-stranded antiparallel beta-sheet (s1 and s2), arranged into a three-layered sandwich fold. This arrangement generates a mostly hydrophobic cavity in the lower half of the domain which can accommodate the cognate ligand. In all hormone-bound LBD structures, the ligand-binding pocket (LBP) is sealed by helix H12. To date, only a very few EDC-bound human NHRs have been crystallized as compared with the 140,000 synthetic chemicals used in consumer products. Furthermore, not or really very few animal NHRs structures have been described. Thus, it appears that efforts in elucidating the mechanisms of human and animal NHR/EDC interactions by crystallography and other structural methods must be pursued in order to deal with dif?cult cases and to increase our knowledge of the structural mechanisms and molecular interactions used by different receptors and a wide range of structurally and chemically diverse compounds. As exempli?ed by organotin compounds, such studies can also reveal unforeseen binding modes and provide guidelines for the rational design of novel NHR modulators. Together with the improvement of computational methods, this mounting structural data should increase the effectiveness of in silico screening strategies. The first objective of BISCOT is to establish human, zebrafish and xenopus ERs, AR, ERRs and PPARs reporter cell lines. If many reporter cell lines expressing human receptors were established, few cell lines expressing animals receptors were described. Thus, BISCOT will increase the number of available reporter cell lines expressing zebrafish and xenopus NHRs and thus enable to better estimate wild life impact of EDCs. The second objective of BISCOT is to increase the number of NHR/ EDCs structures. This task will allow to precise, at the lolecular level, the intimate interactions of NHRs with different structurally unrelated EDCs. The third objective is to generate and evaluate a complete set of 3D models for human, mouse, zebrafish and xenopus NHRs using as templates either known human and mouse crystal structures or structures obtained through BISCOT. These tools will help the scientific community to evaluate EDC effects on human and wild life. The resulting software and model database for focused search on a given human, mouse, zebrafish, xenopus NHR (virtual screening) or on an additional EDC (reverse-docking) will be provided to the scientific community.