Dehydroepiandrosterone and its 7-hydroxylated metabolites do not interfere with the transactivation and cellular trafficking of the glucocorticoid receptor.
The human brain is a target tissue for glucocorticoids (GC). Dehydroepiandrosterone (DHEA) is a neurosteroid produced in the brain where it is transformed into 7alpha-hydroxy-DHEA and 7beta-hydroxy-DHEA. The antiglucocorticoid effects of both 7-hydroxylated metabolites have been investigated with evidence in mice that neither form of DHEA interfered with the binding of GC to its glucocorticoid receptor (GR), but contributed to a decreased nuclear uptake of the activated GR. Our objective was to use COS-7 cell culture to research DHEA, 7alpha-hydroxy-DHEA and 7beta-hydroxy-DHEA interferences with GR trafficking. These cells did not carry out the 7alpha-hydroxylation of DHEA and the oxidation of cortisol into cortisone. The cDNA of the human GR was inserted into pcDNA3 for a transient transfection of COS-7 cells. Human GR transactivation activity was measured from a luciferase-MMTV reporter gene. The transfected COS-7 cells were cultured using 10(-12) to 10(-5) M dexamethasone (DEX) or cortisol, which triggered the reporter expression. Treatment with 10(-12) to 10(-5) M DHEA, 7alpha-hydroxy-DHEA and 7beta-hydroxy-DHEA caused no change in the GC-induced GR transactivation. A reconstruction of the process associated EGFP to the human GR cDNA. Confocal microscopic examination of COS-7 cells transiently expressing the fusion protein EGFP-GR showed nuclear fluorescence 60 min after incubation with 10(-8) M DEX or cortisol. The addition of 10(-5) M DHEA, 7alpha-hydroxy-DHEA or 7beta-hydroxy-DHEA did not change its kinesis and intensity. These results contribute to the knowledge of DHEA, 7alpha-hydroxy-DHEA and 7beta-hydroxy-DHEA, in relation to antiglucocorticoid activity. We conclude that direct interference with GR trafficking can be discounted in the case of these hormones, therefore proposing new possibilities of investigation.
Muller
Caroline
C
Laboratoire de Biotechnologie, EA-3199, Conservatoire National des Arts et Métiers, 2 rue Conté, 75003 Paris, France.
Cluzeaud
Françoise
F
Pinon
Gregory M
GM
Rafestin-Oblin
Marie-Edith
ME
Morfin
Robert
R
D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D003687:Dehydroepiandrosterone / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology*; D006801:Humans; D006900:Hydroxylation; D021381:Protein Transport / Q000187:drug effects; D011965:Receptors, Glucocorticoid / Q000378:metabolism*; D013237:Stereoisomerism; D015533:Transcriptional Activation / Q000187:drug effects*
D011965:Receptors, Glucocorticoid; D003687:Dehydroepiandrosterone; C003587:7-hydroxydehydroepiandrosterone