Determinants of retinoid X receptor transcriptional antagonism.
The synthesis and bioactivity of the retinoid X receptor (RXR) antagonist 4-[(3'-n-butyl-5',6',7',8'-tetrahydro-5',5',8',8'-tetramethyl-2'-naphthalenyl)(cyclopropylidene)methyl]benzoic acid and several heteroatom-substituted analogues are described. Ligand design was based on the scaffold of the 3'-methyl RXR-selective agonist analogue and reports that 3'-n-propyl and longer n-alkyl groups conferred RXR antagonism. The transcriptional antagonism of the 3'-n-butyl analogue was demonstrated by its blockade of retinoic acid receptor (RAR) beta expression induced by the RXRalpha/peroxisome proliferator-activated receptor (PPAR) gamma heterodimer complexed with an RXRalpha agonist plus the PPARgamma agonist ciglitazone and the inhibition of 9-cis-RA-induced coactivator SRC-1a recruitment to RXRalpha. Receptor-ligand docking studies using full-atom flexible ligand and flexible receptor suggested that binding of the antagonist to the RXRalpha antagonist conformation was favored because the salt bridge that formed between the retinoid carboxylate and the RXRalpha helix H5 arginine-321 was far stronger than that formed on its binding to the agonist conformation. The antagonist also blocked activation of RAR subtypes alpha and beta by 9-cis-RA but not that of RARgamma.
Cancer Center, The Burnham Institute, 10901 North Torrey Pines Road, La Jolla, California 92037, USA.
Claudio N
CN
Cavasotto
Gang
G
Liu
Sharon Y
SY
James
Peter D
PD
Hobbs
Valerie J
VJ
Peterson
Ananyo A
AA
Bhattacharya
Siva K
SK
Kolluri
Xiao-kun
XK
Zhang
Mark
M
Leid
Ruben
R
Abagyan
Robert C
RC
Liddington
Marcia I
MI
Dawson
D001565:Benzoates / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D001665:Binding Sites; D003198:Computer Simulation; D015195:Drug Design; D006801:Humans; D008024:Ligands; D018583:Pliability; D011485:Protein Binding; D011487:Protein Conformation; D018168:Receptors, Retinoic Acid / Q000037:antagonists & inhibitors* / Q000502:physiology; D047488:Retinoid X Receptors; D012176:Retinoids / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D055672:Static Electricity; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000037:antagonists & inhibitors* / Q000502:physiology; D014158:Transcription, Genetic / Q000187:drug effects*
D001565:Benzoates; D008024:Ligands; D018168:Receptors, Retinoic Acid; D047488:Retinoid X Receptors; D012176:Retinoids; D014157:Transcription Factors