Danthron functions as a retinoic X receptor antagonist by stabilizing tetramers of the receptor.Zhang, H., Zhou, R., Li, L., Chen, J., Chen, L., Li, C., Ding, H., Yu, L., Hu, L., Jiang, H., Shen, X.
(2011) J Biol Chem 286: 1868-1875
- PubMed: 21084305
- DOI: https://doi.org/10.1074/jbc.M110.166215
- Primary Citation of Related Structures:
- PubMed Abstract:
Retinoic X receptor (RXR) is a promising target for drug discovery against cancer and metabolic syndromes. Here, we identified a specific RXRα antagonist, danthron, from the traditional Chinese medicine rhubarb. Danthron repressed all tested RXRα-involved response element transcription, including the RXRE, PPRE, FXRE, and LXRE. Results from native PAGE and isothermal titration calorimetry (ITC)-based assays indicated that danthron bound to the tetrameric RXRα-LBD in a specific stoichimetric ratio, and such a binding could influence the corepressor SMRT affinity to the receptor. Additionally, a unique tetrameric structure of the apo-RXRα ligand-binding domain (LBD) was determined, which exhibited a larger tetramer interface and different ligand-binding pocket size compared with the one previously reported. Together with the biochemical and biophysical results, the determined crystal structure of danthron-soaked RXRα-LBD suggested a new mechanism for danthron antagonism to tetrameric RXRα. Moreover, the in vivo efficient improvement of insulin sensitivity by danthron was observed in diet-induced obese (DIO) mice. Thus, our findings were expected to supply new insights into the structural basis of RXRα antagonist for its further potential therapeutic application.
State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China.