Identification and Characterization of a Non-retinoid Ligand for Retinol-binding Protein 4 Which Lowers Serum Retinol-binding Protein 4 Levels in Vivo.Motani, A., Wang, Z., Conn, M., Siegler, K., Zhang, Y., Liu, Q., Johnstone, S., Xu, H., Thibault, S., Wang, Y., Fan, P., Connors, R., Le, H., Xu, G., Walker, N., Shan, B., Coward, P.
(2009) J Biol Chem 284: 7673-7680
- PubMed: 19147488
- DOI: https://doi.org/10.1074/jbc.M809654200
- Primary Citation of Related Structures:
- PubMed Abstract:
Retinol-binding protein 4 (RBP4) transports retinol from the liver to extrahepatic tissues, and RBP4 lowering is reported to improve insulin sensitivity in mice. We have identified A1120, a high affinity (K(i) = 8.3 nm) non-retinoid ligand for RBP4, which disrupts the interaction between RBP4 and its binding partner transthyretin. Analysis of the RBP4-A1120 co-crystal structure reveals that A1120 induces critical conformational changes at the RBP4-transthyretin interface. Administration of A1120 to mice lowers serum RBP4 and retinol levels but, unexpectedly, does not improve insulin sensitivity. In addition, we show that Rpb4(-/-) mice display normal insulin sensitivity and are not protected from high fat diet-induced insulin resistance. We conclude that lowering RBP4 levels does not improve insulin sensitivity in mice. Therefore, RBP4 lowering may not be an effective strategy for treating diabetes.
Department of Metabolic Disorders, Amgen, Inc., South San Francisco, California 94080, USA.