Type 2 11 beta-hydroxysteroid dehydrogenase in foetal and adult life.
Two isoforms of 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) catalyse the interconversion of active cortisol to inactive cortisone; 11 beta-HSD1 is a low affinity, NADP(H)-dependent dehydrogenase/oxo-reductase, and 11 beta-HSD2 a high affinity, NAD-dependent dehydrogenase. Because of the importance of 11 beta-HSD in regulating corticosteroid hormone action, we have analysed the distribution of the 11 beta-HSD isoforms in human adult and foetal tissues (including placenta), and, in addition have performed a series of substrate specificity studies on the novel, kidney 11 beta-HSD2 isoform. Using an RT-PCR approach, we failed to detect 11 beta-HSD1 mRNA in any human mid-gestational foetal tissues. In contrast 11 beta-HSD2 mRNA was present in foetal lung, adrenal, colon and kidney. In adult tissues 11 beta-HSD2 gene expression was confined to the mineralocorticoid target tissues, kidney and colon, whilst 11 beta-HSD1 was expressed predominantly in glucocorticoid target tissues, liver, lung, pituitary and cerebellum. In human kidney homogenates, 11-hydroxylated progesterone derivatives, glycyrrhetinic acid, corticosterone and the "end products" cortisone and 11-dehydrocorticosterone were potent inhibitors of the NAD-dependent conversion of cortisol to cortisone. Finally high levels of 11 beta-HSD2 mRNA and activity were observed in term placentae, which correlated positively with foetal weight. The tissue-specific distribution of the 11 beta-HSD isoforms is in keeping with their differential roles, 11 beta-HSD1 regulating glucocorticoid hormone action and 11 beta-HSD2 mineralocorticoid hormone action. The correlation of 11 beta-HSD2 activity in the placenta with foetal weight suggests, in addition, a crucial role for this enzyme in foetal development, possibly in mediating ontogeny of the foetal hypothalamo-pituitary-adrenal axis.
Department of Medicine, Queen Elizabeth Hospital, Edgbaston, Birmingham, U.K.
P M
PM
Stewart
C B
CB
Whorwood
J I
JI
Mason
D042842:11-beta-Hydroxysteroid Dehydrogenases; D000311:Adrenal Glands / Q000196:embryology*; D000328:Adult; D001483:Base Sequence; D001724:Birth Weight; D017931:DNA Primers / Q000737:chemistry; D005333:Fetus / Q000201:enzymology*; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D006913:Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism*; D008969:Molecular Sequence Data; D010920:Placenta / Q000033:anatomy & histology / Q000201:enzymology*; D012333:RNA, Messenger / Q000235:genetics; D013256:Steroids / Q000096:biosynthesis*; D013379:Substrate Specificity
D017931:DNA Primers; D007527:Isoenzymes; D012333:RNA, Messenger; D013256:Steroids; D006913:Hydroxysteroid Dehydrogenases; D042842:11-beta-Hydroxysteroid Dehydrogenases