Nuclear receptors - II. Intestinal corticosteroid receptors

Two corticosteroid receptors have been cloned; they are the glucocorticoid receptor and the mineralocorticoid receptor. These receptors are members of the steroid/thyroid/retinoid receptor family of nuclear transactivating factors, which are characterized by two highly conserved zinc fingers in the central DNA binding domain, a COOH-terminal domain that encompasses the ligand binding site, and a variable NH2-terminal domain. In addition to these cloned receptors, other corticosteroid receptors have recently been identified in intestine. Steroid binding studies have identified two novel putative corticosteroid receptors in intestinal epithelia, and molecular cloning studies have detected two low-affinity receptors in small intestine that are activated by corticosteroids and induce CYP3A gene expression. This article focuses on the identification of these novel corticosteroid receptors and the potential role they may play in intestinal physiology.