Targeting the Alternative Vitamin E Metabolite Binding Site Enables Noncanonical PPAR gamma Modulation.
Arifi, S., Marschner, J.A., Pollinger, J., Isigkeit, L., Heitel, P., Kaiser, A., Obeser, L., Hofner, G., Proschak, E., Knapp, S., Chaikuad, A., Heering, J., Merk, D.(2023) J Am Chem Soc 145: 14802-14810
- PubMed: 37385602 
- DOI: https://doi.org/10.1021/jacs.3c03417
- Primary Citation of Related Structures:  
8ATY, 8ATZ, 8CPH, 8CPI, 8CPJ - PubMed Abstract: 
The lipid-sensing transcription factor PPAR¦Ã is the target of antidiabetic thiazolidinediones (TZD). At two sites within its ligand binding domain, it also binds oxidized vitamin E metabolites and the vitamin E mimetic garcinoic acid. While the canonical interaction within the TZD binding site mediates classical PPAR¦Ã activation, the effects of the second binding on PPAR¦Ã activity remain elusive. Here, we identified an agonist mimicking dual binding of vitamin E metabolites and developed a selective ligand of the second site, unveiling potential noncanonical regulation of PPAR¦Ã activities. We found that this alternative binding event can simultaneously occur with orthosteric ligands and it exerted different effects on PPAR¦Ã-cofactor interactions compared to both orthosteric PPAR¦Ã agonists and antagonists, indicating the diverse roles of the two binding sites. Alternative site binding lacked the pro-adipogenic effect of TZD and mediated no classical PPAR signaling in differential gene expression analysis but markedly diminished FOXO signaling, suggesting potential therapeutic applications.
Organizational Affiliation: 
Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, D-60438 Frankfurt, Germany.