Hexose-6-phosphate dehydrogenase modulates the effect of inhibitors and alternative substrates of 11beta-hydroxysteroid dehydrogenase 1.
Intracellular glucocorticoid reactivation is catalyzed by 11beta-hydroxysteroid dehydrogenase 1 (11beta-HSD1), which functions predominantly as a reductase in cells expressing hexose-6-phosphate dehydrogenase (H6PDH). We recently showed that the ratios of cortisone to cortisol and 7-keto- to 7-hydroxy-neurosteroids are regulated by 11beta-HSD1 and very much depend on coexpression with H6PDH, providing cosubstrate NADPH. Here, we investigated the impact of H6PDH on the modulation of 11beta-HSD1-dependent interconversion of cortisone and cortisol by inhibitors and alternative substrates. Using HEK-293 cells expressing 11beta-HSD1 or coexpressing 11beta-HSD1 and H6PDH, we observed significant differences of 11beta-HSD1 inhibition by natural and pharmaceutical compounds as well as endogenous hormone metabolites. Furthermore, we show potent and dose-dependent inhibition of 11beta-HSD1 by 7-keto-DHEA in differentiated human THP-1 macrophages and in HEK-293 cells overexpressing 11beta-HSD1 with or without H6PDH. In contrast, 7-ketocholesterol (7-KC) did not inhibit 11beta-HSD1 in HEK-293 cells, even in the presence of H6PDH, but inhibited 11beta-HSD1 reductase activity in differentiated THP-1 macrophages (IC(50) 8.1+/-0.9microM). 7-Keto-DHEA but not 7-KC inhibited 11beta-HSD1 in HEK-293 cell lysates. In conclusion, cellular factors such as H6PDH can significantly modulate the effect of inhibitors and alternative 7-oxygenated substrates on intracellular glucocorticoid availability.
Balázs
Zoltán
Z
Division of Molecular and Systems Toxicology, Department of Pharmaceutical Sciences, University of Basel, Klingelbergstrasse 50, CH-4056 Basel, Switzerland.
Nashev
Lyubomir G
LG
Chandsawangbhuwana
Charlie
C
Baker
Michael E
ME
Odermatt
Alex
A
D043205:11-beta-Hydroxysteroid Dehydrogenase Type 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D000818:Animals; D002237:Carbohydrate Dehydrogenases / Q000378:metabolism*; D002457:Cell Extracts; D002460:Cell Line; D003345:Corticosterone / Q000737:chemistry / Q000378:metabolism; D003687:Dehydroepiandrosterone / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D007653:Ketocholesterols / Q000737:chemistry / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects / Q000201:enzymology; D051379:Mice; D008958:Models, Molecular; D013379:Substrate Specificity / Q000187:drug effects
D002457:Cell Extracts; D004791:Enzyme Inhibitors; D007653:Ketocholesterols; D003687:Dehydroepiandrosterone; D002237:Carbohydrate Dehydrogenases; C020552:galactose-6-phosphate dehydrogenase; D043205:11-beta-Hydroxysteroid Dehydrogenase Type 1; C468386:HSD11B1 protein, human; C003001:7-ketocholesterol; D003345:Corticosterone