Synergistic activation of human pregnane X receptor by binary cocktails of pharmaceutical and environmental compounds

Vanessa Delfosse (1) , Beatrice Dendelé (2) , Tiphaine Huet (1) , Marina Grimaldi (2) , Abdelhay Boulahtouf (2) , Sabine Gerbal-Chaloin (3) , Bertrand Beucher (4) , Dominique Roecklin , Christina Muller (5) , Roger Rahmani (5) , Vincent Cavaillès (2) , Martine Daujat-Chavanieu (3) , Valérie Vivat , Jean-Marc Pascussi (4) , Patrick Balaguer (2) , William Bourguet (1)

1 CBS - Centre de Biochimie Structurale [Montpellier]
2 IRCM - U1194 Inserm - UM - Institut de Recherche en Cancérologie de Montpellier
3 Cellules Souches, Plasticité Cellulaire, Médecine Régénératrice et Immunothérapies (IRMB)
4 IGF - Institut de Génomique Fonctionnelle
5 ToxAlim - ToxAlim

Humans are chronically exposed to multiple exogenous substances, including environmental pollutants, drugs and dietary components. Many of these compounds are suspected to impact human health, and their combination in complex mixtures could exacerbate their harmful effects. Here we demonstrate that a pharmaceutical oestrogen and a persistent organochlorine pesticide, both exhibiting low efficacy when studied separately, cooperatively bind to the pregnane X receptor, leading to synergistic activation. Biophysical analysis shows that each ligand enhances the binding affinity of the other, so the binary mixture induces a substantial biological response at doses at which each chemical individually is inactive. High-resolution crystal structures reveal the structural basis for the observed cooperativity. Our results suggest that the formation of 'supramolecular ligands' within the ligand-binding pocket of nuclear receptors contributes to the synergistic toxic effect of chemical mixtures, which may have broad implications for the fields of endocrine disruption, toxicology and chemical risk assessment.

Domaines: Sciences du Vivant [q-bio]

Vanessa Delfosse, Beatrice Dendelé, Tiphaine Huet, Marina Grimaldi, Abdelhay Boulahtouf, et al.. Synergistic activation of human pregnane X receptor by binary cocktails of pharmaceutical and environmental compounds. Nature Communications, 2015, 6 (1), ⟨10.1038/ncomms9089⟩. ⟨hal-01838034⟩