Cytochromes P450 .6. Constitutive expression of hepatic cytochrome P450 genes

One of the more challenging areas for study of the regulation of P450s is understanding the constitutive regulation of hepatic P450s. In this article, Gonzalez and Lee provide insight into how unique tissue-enriched transcription factors regulate expression of many of the hepatic P450s that are not under direct control of the ''xenobiotic'' receptors described by others. These constitutively expressed P450s are principally responsible for eliminating various hydrophobic xenobiotics such as drugs and other man-made chemicals from the body by oxidation reactions that are necessary to make them more water soluble. in addition, these tissue-enriched transcription factors probably dictate the developmental and probably sex-specific expression of P450s in the liver. Many of the tissue-enriched transcription factors are most likely under the control of second message pathways, increasing the potential diversity of regulation of the unique hepatic P450s discussed.