Chiglitazar Preferentially Regulates Gene Expression via Configuration-Restricted Binding and Phosphorylation Inhibition of PPARγ

Figure 3

Chiglitazar binds PPARγ differently from rosiglitazone and pioglitazone. (a)–(c) Simulated molecular docking of each agonist to the crystal structure of PPARγ (PDB code: 2PRG, 2XKW as shown in gray) was performed using Molegro Virtual Docker software. Ros ((a), in cyan, docking to 2PRG) and Pio ((b), in yellow, docking to 2XKW) have typical modes of interaction with the receptor via hydrogen bonding to helix 12 (Tyr-473) and helix 5 (His-323) (residues in green, hydrogen bonds shown in dotted red lines). In this conformation, helix 12, along with helices 3–5, forms the coactivator-binding site (AF-2) responsible for full agonist activity. Chi ((c), in blue, docking to 2XKW) does not form typical hydrogen bonding to helices 12 and 5 but rather forms alternative hydrogen bonds to helix 3 and the receptor β-sheet (residues in green). This conformation is highly similar to the partial agonist MRL-24. (d)–(g) Site-directed mutation of PPARγ differently affects transactivity of different agonists (Ros (d), Pio (e), and Chi (f)) compared with wild-type receptor by reporter gene assay. PPARγ with site-directed mutation at Y473D, E343A, or S289A, respectively, was constructed and applied in reporter gene assay as described in Materials and Methods.