Poster Presentation The 44th Lorne Conference on Protein Structure and Function 2019

Understanding the ligand-selective nuclear hormone receptor activation by fatty acid-binding protein 1 (#178)

Rahul Patil 1 , Biswaranjan Mohanty 1 , Bonan Liu 2 , Indu R. Chandrashekaran 1 , Stephen J. Headey 1 , Martin L. Williams 1 , Craig S. Clements 1 , Olga Ilyichova 1 , Bradley C. Doak 1 , Patrick Genissel 3 , Richard J. Weaver 3 , Laurent Vuillard 3 , Michelle L. Halls 4 , Chris J.H. Porter 2 , Martin J. Scanlon 1
  1. Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, Australia
  2. Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, Australia
  3. Institut de Recherches Servier, 125 Chemin de Ronde, 78290 Croissy-sur-Seine, France
  4. Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC, Australia

Nuclear hormone receptors (NHRs) regulate the expression of genes involved in metabolism, reproduction and development in response to endogenous ligands such as steroids, lipids, and hormones (1). NHRs are major therapeutic targets, but the development of NHR ligands as therapeutics has been hampered by toxicity in non-target organs. Tissue-specific activation of NHRs in response to endogenous ligands is modulated by fatty-acid binding proteins (FABP) which facilitate the nuclear transport of ligands (2,3). Previous studies have demonstrated that FABPs modulate NHR activation in a ligand-selective manner (3). Tissue-specific expression of FABPs and their interaction with NHR ligands can be exploited to provide means to control cellular selectivity of NHR ligands and therefore improve their utility as therapeutics.

 

Here, we investigate the ligand-induced conformational changes in FABP1 that dictate peroxisome proliferator-activated receptor alpha (PPARα) activation in response to the agonist GW7647 (4). To elucidate the mechanism by which FABP1 enhances PPARα activation we mutated residues in the helical cap and loops surrounding the ligand-binding portal region of FABP1. Mutation to Ala of the residues Lys57, Glu77 and Lys96 in the loops surrounding the portal region had little effect on the binding affinity of GW7647 for FABP1, but abolished both nuclear accumulation of FABP1 and PPAR activation in cells treated with GW7647. We determined the structure and dynamics of FABP1 in the absence and presence of GW7647 by solution nuclear magnetic resonance spectroscopy. Analysis of the data revealed little change in the backbone structure or dynamics of FABP1 upon GW7647 binding. However, several residues in the loops surrounding the portal region, including Lys57, Glu77 and Lys96 become more solvent exposed upon ligand binding. Thus, the mechanism that underpins the ability of FABP1 to potentiate PPARα activation by GW7647 involves the stabilization of a conformation of FABP1 that promotes interaction with the receptor.

  1. 1. Aranda, A., and Pascual, A. (2001) Physiol Rev 81, 1269-1304
  2. 2. Huang, H., Starodub, O., McIntosh, A., Atshaves, B. P., Woldegiorgis, G., Kier, A. B., and Schroeder, F. (2004) Biochemistry 43, 2484-2500
  3. 3. Hughes, M. L., Liu, B., Halls, M. L., Wagstaff, K. M., Patil, R., Velkov, T., Jans, D. A., Bunnett, N. W., Scanlon, M. J., and Porter, C. J. (2015) J Biol Chem 290, 13895-13906
  4. 4. Patil, R., Mohanty, B., Liu, B., Chandrashekaran, I. R., Headey, S. J., Williams, M. L., Clements, C. S., Ilyichova, O., Doak, B. C., Genissel, P., Weaver, R. J., Vuillard, L., Halls, M. L., Porter, C. J. H., and Scanlon, M. J. (2018) J Biol Chem (doi:10.1074/jbc.RA118.006848)