Positive Reinforcing Mechanisms between GPR120 and PPARγ Modulate Insulin Sensitivity

Area of Science:

• Metabolic disease research
• Endocrinology
• Pharmacology

Background:

• G protein-coupled receptor 120 (GPR120) and PPARγ agonists independently improve insulin sensitivity.
• The interaction between GPR120 and PPARγ pathways in metabolic regulation remains unexplored.

Purpose of the Study:

• To investigate the functional interaction between GPR120 and PPARγ pathways.
• To determine if combined activation can enhance insulin sensitization and mitigate side effects.

Main Methods:

• Treatment of mice with a PPARγ agonist (rosiglitazone) and a GPR120 agonist (Compound A).
• Analysis of glucose tolerance and insulin sensitivity.
• Mechanistic studies involving gene expression, ligand induction, and signaling pathway analysis (ERK).
• Utilizing macrophage-specific and adipocyte-specific GPR120 knockout (KO) mouse models.

Main Results:

• Combined treatment showed additive effects on glucose tolerance and insulin sensitivity.
• Lower doses of rosiglitazone were effective when combined with Compound A, potentially reducing side effects.
• GPR120 was identified as a PPARγ target gene in adipocytes.
• GPR120 enhances PPARγ activity by inducing 15d-PGJ2 and inhibiting ERK-mediated suppression.
• GPR120 exhibited anti-inflammatory effects via macrophages and cooperated with PPARγ in adipocytes to improve insulin sensitivity.

Conclusions:

• The GPR120 and PPARγ pathways interact synergistically to improve insulin sensitivity.
• Combined activation offers a promising therapeutic strategy for enhanced insulin sensitization with potentially reduced side effects.
• GPR120 plays dual roles in anti-inflammation (macrophages) and insulin sensitization (adipocytes).