The intracellular localization of the mineralocorticoid receptor is regulated by 11beta-hydroxysteroid dehydrogenase type 2.
11beta-hydroxysteroid dehydrogenase (11beta-HSD) type 2 has been considered to protect the mineralocorticoid receptor (MR) by converting 11beta-hydroxyglucocorticoids into their inactive 11-keto forms, thereby providing specificity to the MR for aldosterone. To investigate the functional protection of the MR by 11beta-HSD2, we coexpressed epitope-tagged MR and 11beta-HSD2 in HEK-293 cells lacking 11beta-HSD2 activity and analyzed their subcellular localization by fluorescence microscopy. When expressed alone in the absence of hormones, the MR was both cytoplasmic and nuclear. However, when coexpressed with 11beta-HSD2, the MR displayed a reticular distribution pattern, suggesting association with 11beta-HSD2 at the endoplasmic reticulum membrane. The endoplasmic reticulum membrane localization of the MR was observed upon coexpression only with 11beta-HSD2, but not with 11beta-HSD1 or other steroid-metabolizing enzymes. Aldosterone induced rapid nuclear translocation of the MR, whereas moderate cortisol concentrations (10-200 nm) did not activate the receptor, due to 11beta-HSD2-dependent oxidation to cortisone. Compromised 11beta-HSD2 activity (due to genetic mutations, the presence of inhibitors, or saturating cortisol concentrations) led to cortisol-induced nuclear accumulation of the MR. Surprisingly, the 11beta-HSD2 product cortisone blocked the aldosterone-induced MR activation by a strictly 11beta-HSD2-dependent mechanism. Our results provide evidence that 11beta-HSD2, besides inactivating 11beta-hydroxyglucocorticoids, functionally interacts with the MR and directly regulates the magnitude of aldosterone-induced MR activation.
Odermatt
A
A
Department of Clinical Research, Division of Nephrology and Hypertension, University of Berne, 3010 Berne, Switzerland. alex.odermatt@dkf2.unibe.ch
Arnold
P
P
Frey
F J
FJ
D043209:11-beta-Hydroxysteroid Dehydrogenase Type 2; D021581:Active Transport, Cell Nucleus; D000287:Administration, Topical; D000450:Aldosterone / Q000378:metabolism; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D002460:Cell Line; D002462:Cell Membrane; D002467:Cell Nucleus / Q000378:metabolism; D003345:Corticosterone / Q000494:pharmacology; D003348:Cortisone / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004232:Diuretics / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005665:Furosemide / Q000494:pharmacology; D006034:Glycyrrhetinic Acid / Q000494:pharmacology; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism / Q000494:pharmacology; D006913:Hydroxysteroid Dehydrogenases / Q000737:chemistry* / Q000378:metabolism*; D007700:Kinetics; D008856:Microscopy, Fluorescence; D009154:Mutation; D010100:Oxygen / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011374:Progesterone / Q000378:metabolism; D018161:Receptors, Mineralocorticoid / Q000096:biosynthesis*; D014158:Transcription, Genetic; D014162:Transfection
D000893:Anti-Inflammatory Agents; D004232:Diuretics; D018161:Receptors, Mineralocorticoid; D000450:Aldosterone; D011374:Progesterone; D005665:Furosemide; D006913:Hydroxysteroid Dehydrogenases; D043209:11-beta-Hydroxysteroid Dehydrogenase Type 2; C468387:HSD11B2 protein, human; D006034:Glycyrrhetinic Acid; D010100:Oxygen; D003348:Cortisone; D003345:Corticosterone; D006854:Hydrocortisone