An Unexpected Mode Of Binding Defines BMS948 as A Full Retinoic Acid Receptor β (RARβ, NR1B2) Selective Agonist.
Retinoic acid is an important regulator of cell differentiation which plays major roles in embryonic development and tissue remodeling. The biological action of retinoic acid is mediated by three nuclear receptors denoted RARα, β and γ. Multiple studies support that RARβ possesses functional characteristics of a tumor suppressor and indeed, its expression is frequently lost in neoplastic tissues. However, it has been recently reported that RARβ could also play a role in mammary gland tumorigenesis, thus demonstrating the important but yet incompletely understood function of this receptor in cancer development. As a consequence, there is a great need for RARβ-selective agonists and antagonists as tools to facilitate the pharmacological analysis of this protein in vitro and in vivo as well as for potential therapeutic interventions. Here we provide experimental evidences that the novel synthetic retinoid BMS948 is an RARβ-selective ligand exhibiting a full transcriptional agonistic activity and activating RARβ as efficiently as the reference agonist TTNPB. In addition, we solved the crystal structures of the RARβ ligand-binding domain in complex with BMS948 and two related compounds, BMS641 and BMS411. These structures provided a rationale to explain how a single retinoid can be at the same time an RARα antagonist and an RARβ full agonist, and revealed the structural basis of partial agonism. Finally, in addition to revealing that a flip by 180° of the amide linker, that usually confers RARα selectivity, accounts for the RARβ selectivity of BMS948, the structural analysis uncovers guidelines for the rational design of RARβ-selective antagonists.
Inserm U1054, Centre de Biochimie Structurale, Montpellier, France; CNRS UMR5048, Universités Montpellier 1 & 2, Montpellier, France; CAS in Crystallography and Biophysics, University of Madras, Chennai, India.
Eswarkumar
E
Nadendla
Inserm U1054, Centre de Biochimie Structurale, Montpellier, France; CNRS UMR5048, Universités Montpellier 1 & 2, Montpellier, France.
Catherine
C
Teyssier
Inserm U1054, Centre de Biochimie Structurale, Montpellier, France; CNRS UMR5048, Universités Montpellier 1 & 2, Montpellier, France.
Vanessa
V
Delfosse
Novalix, Illkirch, C.U. de Strasbourg, France.
Valérie
V
Vivat
CAS in Crystallography and Biophysics, University of Madras, Chennai, India.
Gunasekaran
G
Krishnasamy
IGBMC, CNRS/INSERM/UdS/CERBM, Illkirch-Cedex, C.U. de Strasbourg, France.
Hinrich
H
Gronemeyer
Inserm U1054, Centre de Biochimie Structurale, Montpellier, France; CNRS UMR5048, Universités Montpellier 1 & 2, Montpellier, France.
William
W
Bourguet
Inserm U1054, Centre de Biochimie Structurale, Montpellier, France; CNRS UMR5048, Universités Montpellier 1 & 2, Montpellier, France.
Pierre
P
Germain
D018360:Crystallography, X-Ray; D006367:HeLa Cells; D006801:Humans; D007093:Imidazoles / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D008024:Ligands; D008958:Models, Molecular; D011485:Protein Binding / Q000187:drug effects; D017434:Protein Structure, Tertiary; D018168:Receptors, Retinoic Acid / Q000819:agonists* / Q000737:chemistry / Q000378:metabolism*; D000072482:Retinoic Acid Receptor alpha; D013329:Structure-Activity Relationship
D007093:Imidazoles; D008024:Ligands; C000607071:RARA protein, human; D018168:Receptors, Retinoic Acid; D000072482:Retinoic Acid Receptor alpha; C082925:retinoic acid receptor beta