Mineralocorticoid Receptor

Mineralocorticoid receptor (MR) is an intracellular steroid hormone receptor, and a member of the nuclear receptor superfamily, that mediates the physiological action of two important adrenal steroids, aldosterone and cortisol. Mineralocorticoid receptor is closely related to the glucocorticoid receptor (GR), and it can indifferently bind mineralocorticoid and glucocorticoid hormones. Activation of the mineralocorticoid receptor in the distal nephron by its ligand, aldosterone, plays an important role in sodium reabsorption and blood pressure regulation. Besides the regulation of sodium balance and the control of blood pressure, aldosterone-human mineralocorticoid receptor tandem also exerts important regulatory functions on the cardiovascular and central nervous systems.

Mineralocorticoid receptor participates in the regulation of hydroelectrolytic homeostasis in sodium-transporting tight epithelia such as distal nephron, colon, lung, and salivary and sweat glands. In such epithelial target cells, the mineralocorticoid specificity of aldosterone action is given by the enzyme 11β-hydroxysteroid dehydrogenase 2 (11-HSD2), which converts active glucocorticoids into inactive metabolites. Mineralocorticoid receptor is also expressed in nonepithelial tissues such as the heart, some areas of the brain, large blood vessels, and mononuclear leukocytes. The ligand-activated mineralocorticoid receptor is translocated in the nucleus and acts as a transcription factor after its interaction with the consensus glucocorticoid response element (GRE) sequences. Mineralocorticoid receptor could activate or inhibit transcription of target genes whose identification is under intense investigation.