Glucocorticoid Regulation of the Promoter of 11β-Hydroxysteroid Dehydrogenase Type 1 Is Indirect and Requires CCAAT/Enhancer-Binding Protein-β

Abstract

11beta-Hydroxysteroid dehydrogenase type 1 (11beta-HSD1) converts inert 11keto-glucocorticoids to active 11beta-hydroxy forms, thereby amplifying intracellular glucocorticoid action. Up-regulation of 11beta-HSD1 in adipose tissue and liver is of pathogenic importance in metabolic syndrome. However, the mechanisms controlling 11beta-HSD1 transcription are poorly understood. Glucocorticoids themselves potently increase 11beta-HSD1 expression in many cells, providing a potential feed-forward system to pathology. We have investigated the molecular mechanisms by which glucocorticoids regulate transcription of 11beta-HSD1, exploiting an A549 cell model system in which endogenous 11beta-HSD1 is expressed and is induced by dexamethasone. We show that glucocorticoid induction of 11beta-HSD1 is indirect and requires new protein synthesis. A glucocorticoid-responsive region maps to between -196 and -88 with respect to the transcription start site. This region contains two binding sites for CCAAT/enhancer-binding protein (C/EBP) that together are essential for the glucocorticoid response and that bind predominantly C/EBPbeta, with C/EBPdelta present in a minority of the complexes. Both C/EBPbeta and C/EBPdelta are rapidly induced by glucocorticoids in A549 cells, but small interfering RNA-mediated knockdown shows that only C/EBPbeta reduction attenuates the glucocorticoid induction of 11beta-HSD1. Chromatin immunoprecipitation studies demonstrated increased binding of C/EBPbeta to the 11beta-HSD1 promoter in A549 cells after glucocorticoid treatment. A similar mechanism may apply in adipose tissue in vivo where increased C/EBPbeta mRNA levels after glucocorticoid treatment were associated with increased 11beta-HSD1 expression. C/EBPbeta is a key mediator of metabolic and inflammatory signaling. Positive regulation of 11beta-HSD1 by C/EBPbeta may link amplification of glucocorticoid action with metabolic and inflammatory pathways and may represent an endogenous innate host-defense mechanism.

The role and regulation of 11β-hydroxysteroid dehydrogenase type 1 in the inflammatory response

“…Thus, PPARα (Hermanowski-Vosatka et al, 2000), PPARγ (Berger et al, 2001), HNF1α (Shih et al, 2001) and LXRα (Stulnig et al, 2002) all decrease 11β-HSD1 mRNA levels, but none act directly. Similarly, glucocorticoid regulation of HSD11B1 gene transcription, at least in human skin fibroblasts and A549 lung epithelial cells is indirect (Hammami and Siiteri, 1991;Sai et al, 2008). In the latter, glucocorticoid induction requires C/EBPβ binding to the P2 promoter (Sai et al, 2008).…”

“…Similarly, glucocorticoid regulation of HSD11B1 gene transcription, at least in human skin fibroblasts and A549 lung epithelial cells is indirect (Hammami and Siiteri, 1991;Sai et al, 2008). In the latter, glucocorticoid induction requires C/EBPβ binding to the P2 promoter (Sai et al, 2008). In human amnion fibroblasts, C/EBPα has been implicated in the glucocorticoid regulation, acting together with glucocorticoid receptor to bind to and regulate the P2 promoter (Yang et al, 2007).…”

“…In cells with more modest levels of C/EBPα or none at all, C/EBPβ, if it receives the appropriate post-translational signals or is increased to sufficiently high levels, activates the 11β-HSD1 P2 promoter. A549 cells contain very low levels of C/EBPα, as do 3T3-L1 preadipocytes (Cao et al, 1991;Li et al, 1995;Sai et al, 2008). C/EBPα, essential for myeloid cell differentiation (Zhang et al, 1997) and a neonatal inflammatory response (Burgess-Beusse and Darlington, 1998) has been shown to decrease the transactivation potential of C/EBPβ through control of isoforms expressed (Burgess-Beusse et al, 1999) and thus may suppress transactivation by C/EBPβ in liver under normal circumstances.…”

Antcin A, a steroid-like compound from Antrodia camphorata, exerts anti-inflammatory effect via mimicking glucocorticoids

“…In order to facilitate docking process, we removed DAC and SRC-1 from GR, as well as the surrounding water molecules. Noticing that cortisone was converted to cortisol, a more active form, by 11β-hydroxysteroid dehydrogenase in liver [23] , we assumed that the carbonyl group attached to C-11 of antcin A was possibly converted to a hydroxyl group in the A549 cells by their endogenous 11β-hydroxysteroid dehydrogenase activity [24] . Thus, antcin A (11β-hydroxyl form), cortisol and dexamethasone were used as GR ligands for docking simulation, and they were constructed and minimized with consistent force field [25] using the Discover Studio 2.0 (DS) package (http://accelrys.com/ about/legal/) [26] .…”

The emerging role of C/EBPs in glucocorticoid signaling: lessons from the lung

“…A CCAAT box motif has been identified in the promoter of 11b-hydroxysteroid dehydrogenase type 1 (11b-HSD1), an enzyme that converts inactive cortisol to active cortisone by reduction (Tannin et al 1991, Sai et al 2008. Cortisol activation by 11b-HSD1 appears to be important for lung maturation, since 11b-HSD1 K/K mice exhibit impaired lung development and depletion of pulmonary surfactant (Hundertmark et al 2002).…”