The nuclear pregnane X receptor regulates xenobiotic detoxification

Area of Science:

• Biochemistry
• Pharmacology
• Toxicology

Background:

• The pregnane X receptor (PXR) is a nuclear receptor that acts as a defense mechanism against toxic substances (xenobiotics).
• PXR is activated by a wide range of lipophilic compounds, including pharmaceuticals, herbal remedies, pesticides, and environmental contaminants.
• Its large, flexible ligand-binding pocket allows it to bind diverse molecules.

Purpose of the Study:

• To highlight the role of PXR in xenobiotic metabolism and detoxification.
• To explain the molecular basis of drug-drug interactions mediated by PXR activation.
• To emphasize the utility of PXR activation assays in predicting and preventing adverse drug events.

Main Methods:

• The study reviews the known functions and characteristics of PXR.
• It discusses the interaction of PXR with various xenobiotics, including prescription drugs and herbal supplements like St. John's wort.
• The mechanism of PXR-mediated gene regulation and its role in drug metabolism are examined.

Main Results:

• PXR forms a heterodimer with the 9-cis retinoic acid receptor (RXR) to regulate genes involved in detoxification and excretion.
• Activation of PXR by common drugs and herbs is a significant cause of drug-drug interactions.
• The promiscuous binding of PXR contributes to its broad substrate specificity.

Conclusions:

• PXR is a critical player in the body's response to xenobiotics.
• Understanding PXR activation is essential for managing drug-drug interactions.
• PXR activation assays offer a valuable tool for predicting and mitigating potential drug interactions.