Nuclear receptor subfamily 1 group I member 2 (PXR) (PXR)

The Nuclear receptor subfamily 1 group I member 2 (PXR), commonly known as the Pregnane X receptor, is a ligand-activated transcription factor that serves as a master regulator of xenobiotic and endobiotic metabolism [2, 4]. Primarily expressed in the liver and intestines, PXR senses a diverse array of foreign substances, including prescription drugs, environmental toxins, and dietary components [6, 11]. Upon activation, it forms a heterodimer with the Retinoid X Receptor (RXR) and binds to specific response elements to induce the expression of key detoxification enzymes, such as Cytochrome P450 3A4 (CYP3A4), and drug transporters like Multidrug Resistance Protein 1 (MDR1) [4, 15]. Beyond its role in drug clearance, PXR is involved in the regulation of bile acid, lipid, and glucose homeostasis, as well as inflammatory responses [3, 5]. Dysregulation of PXR signaling is implicated in various pathologies, including cholestatic liver disease, inflammatory bowel disease, and metabolic syndrome [6, 9]. In oncology, PXR activation can lead to chemoresistance by accelerating the metabolism and efflux of chemotherapeutic agents [11, 19]. Consequently, PXR is a critical consideration in drug development due to its propensity to mediate clinically significant drug-drug interactions [13, 17].

Other names

Pregnane X receptorSteroid and xenobiotic receptorSXROrphan nuclear receptor PAR1PARNR1I2BXRONR1SAR

Acts as a ligand-activated transcription factor that, upon binding a variety of xenobiotics or endobiotics, translocates to the nucleus and forms a heterodimer with the Retinoid X Receptor (RXR). This complex binds to response elements in the promoters of target genes, such as CYP3A4 and ABCB1, to induce their transcription and enhance the detoxification and clearance of substances [4, 11, 15].