title: An Endogenous Mammalian Retinoid X Receptor Ligand, At Last!
abstract: 9-cis-Retinoic acid was identified and claimed to be the endogenous ligand of the retinoid X receptors (RXRs) in 1992. Since then, the endogenous presence of this compound has never been rigorously confirmed. Instead, concerns have been raised by other groups that have reported that 9-cis-retinoic acid is undetectable or that its presence occurs at very low levels. Furthermore, these low levels could not satisfactorily explain the physiological activation of RXR. Alternative ligands, among them various lipids, have also been identified, but also did not fulfill criteria for rigorous endogenous relevance, and their consideration as bona fide endogenous mammalian RXR ligand has likewise been questioned. Recently, novel studies claim that the saturated analogue 9-cis-13,14-dihydroretinoic acid functions as an endogenous physiologically relevant mammalian RXR ligand.
authors.affiliation: Departamento de Química Orgánica, Facultade de Química, CINBIO and IBIV, Universidade de Vigo, Campus As Lagoas-Marcosende, 36310, Vigo, Spain. qolera@uvigo.es.
authors.forename: Ángel R
authors.identifier: 0000-0001-6896-9078
authors.initials: ÁR
authors.lastname: de Lera
authors.affiliation: Institut de Génétique et de Biologie Moléculaire et Cellulaire, Institut de la Santé et de la Recherche Médicale, U964, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7104, Université de Strasbourg, Fédération de Médecine Translationnelle de Strasbourg, 67404, Illkirch, France.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Krezel
authors.affiliation: Paprika Bioanalytics BT, Debrecen, Hungary.|MTA-DE, Public Health Research Group of the Hungarian Academy of Sciences, Faculty of Public Health, University of Debrecen, Hungary.
authors.forename: Ralph
authors.initials: R
authors.lastname: Rühl
mesh_terms: D000077556:Alitretinoin; D001665:Binding Sites; D001688:Biological Products / Q000737:chemistry / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D005231:Fatty Acids, Unsaturated / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D007536:Isomerism; D008024:Ligands; D056004:Molecular Dynamics Simulation; D017434:Protein Structure, Tertiary; D047488:Retinoid X Receptors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D053719:Tandem Mass Spectrometry; D015533:Transcriptional Activation; D014212:Tretinoin / Q000097:blood / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001688:Biological Products; D005231:Fatty Acids, Unsaturated; D008024:Ligands; D047488:Retinoid X Receptors; D000077556:Alitretinoin; D014212:Tretinoin
keywords: dihydroretinoids; endogenous ligands; receptors; retinoids; vitamins