Molecular insight into the activator and deactivator mutations of peroxisome proliferator-activated receptor gamma

Area of Science:

• Molecular biology
• Genetics
• Biochemistry

Background:

• Peroxisome proliferator-activated receptor gamma (PPARγ) is a nuclear receptor crucial for regulating inflammation, lipid metabolism, glucose homeostasis, and adipogenesis.
• Mutations in PPARγ can either activate or deactivate its function, leading to significant physiological consequences.
• Deactivating PPARγ variants often act as dominant-negative forms, interfering with normal receptor activity and causing metabolic disorders such as severe insulin resistance and familial partial lipodystrophy type 3.

Purpose of the Study:

• To elucidate the molecular mechanisms underlying PPARγ mutations.
• To understand how activating and deactivating variants impact receptor function and lead to disease.
• To provide insights for the development of precision therapies targeting PPARγ.

Main Methods:

• Analysis of deactivating PPARγ variants, including their effects on coactivator sequestration, ligand recognition, AF-2 surface stability, and corepressor binding.
• Investigation of activating PPARγ mutations, focusing on their impact on helix 12 stabilization, coactivator recruitment, and ligand-independent transcription.
• Utilizing molecular dynamics simulations to study conformational changes and altered coactivator binding in response to mutations.
• Classification of PPARγ mutations based on their functional impact (dominant-negative or drug-rescuable).

Main Results:

• Deactivating PPARγ mutations, often located in ligand-binding or DNA-binding domains, impair receptor function through various mechanisms.
• Activating PPARγ mutations enhance receptor activity by stabilizing key structural elements and improving coactivator interactions.
• Molecular dynamics simulations revealed that these mutations alter the receptor's conformational equilibrium and coactivator binding dynamics.
• The study provides a framework for classifying mutations and understanding their therapeutic implications.

Conclusions:

• Understanding the molecular basis of PPARγ mutations is critical for comprehending metabolic disorders.
• The mechanistic insights gained from studying these variants are essential for designing selective PPARγ modulators for precision medicine.
• This knowledge aids in classifying mutations and identifying potential drug-rescuable targets for therapeutic intervention.