11 beta-Hydroxysteroid dehydrogenases: tissue-specific dictators of glucocorticoid action.

11 beta-HSD catalyses the interconversion of active and inactive corticosteroids and exists as two isoforms with less than 30% amino acid homology. The bi-directional NADP-dependent type 1 enzyme appears to function as a tissue-specific glucocorticoid provider. The uni-directional NAD-dependent type 2 enzyme functions as a tissue-specific glucocorticoid protector. The syndrome of AME is caused by mutations in the gene of 11 beta-HSD2. Placental 11 beta-HSD2 is a barrier to growth-retarding maternal glucocorticoids and may play a key role in prenatal programming of hypertension.