Novel Dual PPAR δ/γ Partial Agonist Induces Hepatic Lipid Accumulation through Direct Binding and Inhibition of AKT1 Phosphorylation, Mediating CD36 Upregulation

ZLY06 is a dual agonist of peroxisome proliferator-activated receptor (PPAR) δ/γ, showing potential therapeutic effects on metabolic syndrome. However, our research has revealed that ZLY06 exhibits hepatotoxicity in normal C57BL/6J mice, though the precise mechanism remains unclear. This study aims to investigate the manifestations and mechanisms of ZLY06-induced hepatotoxicity. We administered ZLY06 via oral gavage to C57BL/6J mice (once daily for six weeks) and monitored various indicators to preliminarily explore its hepatotoxicity. Additionally, we further investigate the specific mechanisms of ZLY06-induced hepatotoxicity using PPAR inhibitors (GW9662 and GSK0660) and the Protein kinase B (AKT) activator (SC79). Results showed that ZLY06 led to increased serum ALP, ALT and AST, as well as elevated liver index and hepatic lipid levels. There was upregulation in the gene and protein expression of lipid metabolism-related molecules Acc, Scd1, Cd36, Fabp1 and Fabp2 in hepatocytes, with Cd36 showing the most significant change. Furthermore, cotreatment with SC79 significantly reduced ZLY06-induced hepatotoxicity in AML12 cells, evidenced by decreased intracellular TG levels and downregulation of CD36 expression. Specific knockdown of CD36 also mitigated ZLY06-induced hepatotoxicity. The study found that ZLY06 may bind to AKT1, inhibiting its phosphorylation activation, with the downregulation of p-AKT1 preceding the upregulation of CD36. In summary, ZLY06 mediates the upregulation of CD36 by potentially binding to and inhibiting the phosphorylation of AKT1, leading to hepatic lipid metabolism disorder and inducing liver toxicity.