Phenobarbital Response Elements of Cytochrome P450 Genes and Nuclear Receptors

作者：Tatsuya Sueyoshi, Masahiko Negishi · 发表于：The Annual Review of Pharmacology and Toxicology · 年份：2001 · DOI：10.1146/annurev.pharmtox.41.1.123 · 被引用次数：363 · 研究领域：Pharmacogenetics and Drug Metabolism、Estrogen and related hormone effects、Drug Transport and Resistance Mechanisms

Phenobarbital (PB) response elements are composed of various nuclear receptor (NR)-binding sites. A 51-bp distal element PB-responsive enhancer module (PBREM) conserved in the PB-inducible CYP2B genes contains two NR-binding direct repeat (DR)-4 motifs. Responding to PB exposure in liver, the NR constitutive active receptor (CAR) translocates to the nucleus, forms a dimer with the retinoid X receptor (RXR), and activates PBREM via binding to DR-4 motifs. For CYP3A genes, a common NR site [DR-3 or everted repeat (ER)-6] is present in proximal promoter regions. In addition, the distal element called the xenobiotic responsive module (XREM) is found in human CYP3A4 genes, which contain both DR-3 and ER-6 motifs. Pregnane X receptor (PXR) could bind to all of these sites and, upon PB induction, a PXR:RXR heterodimer could transactivate XREM. These response elements and NRs are functionally versatile, and capable of responding to distinct but overlapping groups of xenochemicals.