title: Autocrine positive regulatory feedback of glucocorticoid secretion: glucocorticoid receptor directly impacts H295R human adrenocortical cell function.
abstract: Glucocorticoid receptor (GR), a ubiquitous transcriptional factor, regulates target gene expression upon activation by glucocorticoids, notably cortisol, a corticosteroid hormone synthesized in the adrenal cortex. We thus hypothesized that both GR and cortisol might be involved in the regulation of adrenal physiology and steroidogenesis in an autocrine manner. In a cortisol-secreting human adrenocortical cell line (H295R), the GR-dependent signaling pathway was pharmacologically modulated either by dexamethasone (DEX), a GR agonist or by RU486, a GR antagonist, or was knocked-down by small interfering RNA strategy (SiRNA). We showed that GR activation, elicited by 48 h exposure to DEX, exerts a global positive regulatory effect on adrenal steroidogenesis as revealed by a 1.5- to 2-fold increase in cortisol, 11-deoxycortisol and 17-hydroxyprogesterone secretion associated with a significant enhanced expression of steroidogenesis factors such as StAR, CYP11A1, CYP21A2 and CYP11B1. In sharp contrast, RU486 treatment exerted opposite effects by decreasing both steroid production and expression of these steroidogenic factors. Likewise, GR repression by SiRNA also significantly reduced StAR, CYP11A1, and CYP11B1 mRNA levels. Interestingly, RU486 resulted in a significant CYP21A2 enzymatic blockade as demonstrated by a massive increase in 17-hydroxyprogesterone concentrations in RU486-treated H295R cell supernatants, while cortisol and 11-deoxycortisol secretions were reduced by more than 60%. Consistently, we also demonstrated that metabolic conversion of 17-hydroxyprogesterone into 11-deoxycortisol onto H295R cells was drastically blunted in the presence of RU 486. Finally, steady state levels of MC2R transcripts encoding for the ACTH receptor were significantly induced by DEX, unlikely through a direct GR-mediated transcriptional activation as opposed to CYP11A1 and FKBP5 target genes. These results could account for a higher glucocorticoid-elicited ACTH sensitivity of adrenocortical cells. Our study identifies a positive ultra-short regulatory loop exerted by GR on steroidogenesis in H295R cells, thus supporting a complex intra-adrenal GR-mediated feedback, likely relevant for human adrenocortical pathologies.
authors: Inserm, U693, Le Kremlin-Bicêtre F-94276, France; Faculté de Médecine Paris-Sud, Univ Paris-Sud, UMR-S693, Le Kremlin-Bicêtre F-94276, France.
authors: Laetitia
authors: L
authors: Asser
authors: Inserm, U693, Le Kremlin-Bicêtre F-94276, France; Faculté de Médecine Paris-Sud, Univ Paris-Sud, UMR-S693, Le Kremlin-Bicêtre F-94276, France.
authors: Ségolène
authors: S
authors: Hescot
authors: Inserm, U693, Le Kremlin-Bicêtre F-94276, France; Faculté de Médecine Paris-Sud, Univ Paris-Sud, UMR-S693, Le Kremlin-Bicêtre F-94276, France.
authors: Say
authors: S
authors: Viengchareun
authors: Service d'Endocrinologie, Centre Hospitalier de Reims, F-51092, France.
authors: Brigitte
authors: B
authors: Delemer
authors: Inserm, U693, Le Kremlin-Bicêtre F-94276, France; Faculté de Médecine Paris-Sud, Univ Paris-Sud, UMR-S693, Le Kremlin-Bicêtre F-94276, France; Service de Génétique Moléculaire, Pharmacogénétique, Hormonologie, Assistance Publique-Hôpitaux de Paris, CHU de Bicêtre, Le Kremlin-Bicêtre F-94275, France.
authors: Séverine
authors: S
authors: Trabado
authors: Inserm, U693, Le Kremlin-Bicêtre F-94276, France; Faculté de Médecine Paris-Sud, Univ Paris-Sud, UMR-S693, Le Kremlin-Bicêtre F-94276, France; Service d'Endocrinologie et des Maladies de la Reproduction, Assistance Publique-Hôpitaux de Paris, CHU de Bicêtre, Le Kremlin-Bicêtre F-94275, France. Electronic address: marc.lombes@u-psud.fr.
authors: Marc
authors: M
authors: Lombès
mesh_terms: D019326:17-alpha-Hydroxyprogesterone / Q000378:metabolism*; D000302:Adrenal Cortex / Q000166:cytology / Q000378:metabolism*; D019898:Autocrine Communication / Q000187:drug effects / Q000502:physiology*; D045744:Cell Line, Tumor; D003350:Cortodoxone / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D055785:Gene Knockdown Techniques; D005938:Glucocorticoids / Q000494:pharmacology; D006727:Hormone Antagonists / Q000494:pharmacology; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism*; D015735:Mifepristone / Q000494:pharmacology; D011965:Receptors, Glucocorticoid / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D005938:Glucocorticoids; D006727:Hormone Antagonists; D011965:Receptors, Glucocorticoid; D015735:Mifepristone; D019326:17-alpha-Hydroxyprogesterone; D003907:Dexamethasone; D003350:Cortodoxone; D006854:Hydrocortisone
keywords: Adrenocortical cell; Glucocorticoid biosynthesis; Glucocorticoid receptor