title: Selective ligand activity at Nur/retinoid X receptor complexes revealed by dimer-specific bioluminescence resonance energy transfer-based sensors.
abstract: Retinoid X receptors (RXRs) play a role as master regulators because of their capacity to form heterodimers with other nuclear receptors (NRs). Accordingly, retinoid signaling is involved in multiple biologic processes, including development, cell differentiation, metabolism, and cell death. However, the role and function of RXRs in different heterodimer complexes remain unidentified, mainly because most RXR drugs (called rexinoids) are not selective of specific heterodimer complexes. The lack of selectivity strongly limits the use of rexinoids for specific therapeutic approaches. To better characterize rexinoids at specific NR complexes, we have developed and optimized luciferase (Luc) protein complementation(PCA)-based bioluminescence resonance energy transfer (BRET) assays that can directly measure recruitment of a coactivator (CoA) motif fused to yellow fluorescent protein (YFP) by specific NR dimers. To validate the assays, we compared rexinoid modulation of CoA recruitment by the RXR homodimer and by the heterodimers Nur77/RXR and Nurr1/RXR. Results revealed that some rexinoids display selective CoA recruitment activities with homo- or heterodimer complexes. In particular, SR11237 (BMS649) has stronger potency for recruitment of CoA motif and transcriptional activity with the heterodimer Nur77/RXR than other complexes. This technology should be useful in identifying new compounds with specificity for individual dimeric species formed by NRs.
authors.affiliation: *Faculté de Pharmacie and Groupe de Recherche Universitaire sur le Médicament, and Institut de Recherche en Immunologie et Cancérologie, Université de Montréal, Montréal, Québec, Canada.
authors.forename: Xavier C
authors.initials: XC
authors.lastname: Giner
authors.affiliation: *Faculté de Pharmacie and Groupe de Recherche Universitaire sur le Médicament, and Institut de Recherche en Immunologie et Cancérologie, Université de Montréal, Montréal, Québec, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Cotnoir-White
authors.affiliation: *Faculté de Pharmacie and Groupe de Recherche Universitaire sur le Médicament, and Institut de Recherche en Immunologie et Cancérologie, Université de Montréal, Montréal, Québec, Canada.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Mader
authors.affiliation: *Faculté de Pharmacie and Groupe de Recherche Universitaire sur le Médicament, and Institut de Recherche en Immunologie et Cancérologie, Université de Montréal, Montréal, Québec, Canada daniel.levesque.1@umontreal.ca.
authors.forename: Daniel
authors.initials: D
authors.lastname: Lévesque
mesh_terms: D000077556:Alitretinoin; D020816:Amino Acid Motifs / Q000235:genetics; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001565:Benzoates / Q000494:pharmacology; D060807:Bioluminescence Resonance Energy Transfer Techniques / Q000379:methods*; D057809:HEK293 Cells; D006801:Humans; D008024:Ligands; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D046912:Multiprotein Complexes / Q000737:chemistry / Q000378:metabolism; D056918:Nuclear Receptor Coactivators / Q000235:genetics / Q000378:metabolism; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D057126:Nuclear Receptor Subfamily 4, Group A, Member 2 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D055503:Protein Multimerization; D047491:Retinoid X Receptor gamma / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012176:Retinoids / Q000494:pharmacology; D014212:Tretinoin / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D001565:Benzoates; D008024:Ligands; D008164:Luminescent Proteins; D046912:Multiprotein Complexes; C539821:NR4A1 protein, human; D056918:Nuclear Receptor Coactivators; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D057126:Nuclear Receptor Subfamily 4, Group A, Member 2; D047491:Retinoid X Receptor gamma; D012176:Retinoids; C054562:yellow fluorescent protein, Bacteria; C087130:SR 11237; D000077556:Alitretinoin; D014212:Tretinoin
keywords: cofactor recruitment; nuclear receptors; pharmacological parameters; protein conformation; receptor dimerization