11-Beta-Hydroxysteroid Dehydrogenase Type 3 (HSD11b3)

HSD11B catalyzes the interconversion between active and inactive glucocorticoid, and is known to exist as two distinct isozymes: HSD11B1 and HSD11B2. A third HSD11B isozyme, HSD11B1L, has recently been identified. Human HSD11B1L, which was characterized as a unidirectional NADP(+)-dependent cortisol dehydrogenase, appears to be specifically expressed in the brain. HSD11B1 and abundant HSD11B2 isozymes are expressed in neonatal pig testis and the Km for cortisol of NADP(+)-dependent dehydrogenase activity of testicular microsomes obviously differs from the same activity catalyzed by HSD11B1 from pig liver microsomes. Despite reductions in the production of 11KT, DHT did not affect the expression of targeted genes in the steroidogenic pathway such as steroidogenic acute regulatory protein (star), P450 side chain cleavage (cyp11a1) and 11β-hydroxysteroid dehydrogenase (hsd11b3).