Targeting peroxisome proliferator-activated receptor γ proteasomal degradation by magnolol is a potential avenue for adipogenesis-mediated metabolic homeostasis

Objective

Adipogenesis has been recognized as an attractive avenue for maintaining systemic homeostasis, with peroxisome proliferator-activated receptor γ (PPARγ) showing predominant roles in this process. This study aims to identify promising drug candidates by targeting PPARγ for adipogenesis-based metabolic homeostasis and to clarify the detailed mechanisms.

Methods

Molecular events contributing to adipogenesis were screened, which identified PPARγ as having the predominant role. Promising agents of adipogenesis agonism were screened using a PPARγ-based luciferase reporter assay. The functional capacity and molecular mechanisms of magnolol were intensively examined using 3T3-L1 preadipocytes and dietary models.

Results

This study found that F-box only protein 9 (FBXO9)-mediated lysine 11 (K11)-linked ubiquitination and proteasomal degradation of PPARγ are critically required during adipogenesis and systemic homeostasis. Notably, magnolol was identified as a potent adipogenesis activator by stabilizing PPARγ. The pharmacological mechanisms investigations clarified that magnolol directly binds to PPARγ and markedly interrupts its interaction with FBXO9, leading to a decline in K11-linked ubiquitination and proteasomal degradation of PPARγ. Clinically important, magnolol treatment significantly facilitates adipogenesis in vitro and in vivo.

Conclusions

The downregulation of K11-linked ubiquitination of PPARγ caused by FBOX9 is essentially required for adipogenesis, while targeting PPARγ-FBXO9 interaction provides a new avenue for the therapy of adipogenesis-related metabolic disorder.