CCAAT/enhancer-binding proteins (C/EBPs) regulate the basal and cAMP-induced transcription of the human 11beta-hydroxysteroid dehydrogenase encoding gene in adipose cells

Temperature modulates the osmosensitivity of tilapia prolactin cells

In euryhaline fish, prolactin (Prl) plays an essential role in freshwater (FW) acclimation. In the euryhaline and eurythermal Mozambique tilapia, Oreochromis mossambicus, Prl cells are model osmoreceptors, recently described to be thermosensitive. To investigate the effects of temperature on osmoreception, we incubated Prl cells of tilapia acclimated to either FW or seawater (SW) in different combinations of temperatures (20, 26 and 32 °C) and osmolalities (280, 330 and 420 mOsm/kg) for 6 h. Release of both Prl isoforms, Prl188 and Prl177, increased in hyposmotic media and were further augmented with a rise in temperature. Hyposmotically-induced release of Prl188, but not Prl177, was suppressed at 20 °C. In SW fish, mRNA expression of prl188 increased with rising temperatures at lower osmolalities, while and prl177 decreased at 32 °C and higher osmolalities. In Prl cells of SW-acclimated tilapia incubated in hyperosmotic media, the expressions of Prl receptors, prlr1 and prlr2, and the stretch-activated Ca2+ channel, trpv4,decreased at 32 °C, suggesting the presence of a cellular mechanism to compensate for elevated Prl release. Transcription factors, pou1f1, pou2f1b, creb3l1, cebpb, stat3, stat1a and nfat1c, known to regulate prl188 and prl177, were also downregulated at 32 °C. Our findings provide evidence that osmoreception is modulated by temperature, and that both thermal and osmotic responses vary with acclimation salinity.

Temperature modulates the osmosensitivity of tilapia prolactin cells

In euryhaline fish, prolactin (Prl) plays an essential role in freshwater (FW) acclimation. In the euryhaline and eurythermal Mozambique tilapia, Oreochromis mossambicus, Prl cells are model osmoreceptors, recently described to be thermosensitive. To investigate the effects of temperature on osmoreception, we incubated Prl cells of tilapia acclimated to either FW or seawater (SW) in different temperature (20, 26 and 32°C) and osmolality (280, 330 and 420 mOsm/kg) combinations for 6 h. Release of both Prl isoforms, Prl188 and Prl177, increased in hyposmotic media and were further augmented with a rise in temperature. Hyposmotically-induced release of Prl188 was inhibited at 20°C. In SW fish, mRNA expression of prl188 and prl177 showed direct and inverse relationships with temperature, respectively. In SW-acclimated tilapia Prl cells incubated in hyperosmotic media, Prl receptors, prlr1 and prlr2, and the stretch-activated Ca2+ channel, trpv4, were inhibited at 32°C, suggesting the presence of a cellular mechanism to compensate for elevated Prl release. Transcription factors, pou1f1, pou2f1b, creb3l1, cebpb, stat3, stat1a and nfat1c, known to regulate prl188 and prl177, were also downregulated at 32°C. Our findings provide evidence that osmoreception is modulated by temperature, and that both thermal and osmotic responses vary with acclimation salinity.

C/EBPδ drives key endocrine signals in the human amnion at parturition

Amnion-derived prostaglandin E2 (PGE2) and cortisol are key to labor onset. Identification of a common transcription factor driving the expression of both cyclooxygenase-2 (COX-2) and 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1), the key enzymes in their production, may hold the key to the treatment of pre-term labor. Here, we have found that the CCAAT enhancer binding protein δ (C/EBPδ) is such a transcription factor which underlies the feed-forward induction of COX-2 and 11β-HSD1 expression by their own products PGE2 and cortisol in human amnion fibroblasts so that their production would be ensured in the amnion for the onset of labor. Moreover, the abundance of C/EBPδ in the amnion increases along with COX-2 and 11β-HSD1 at term and further increases at parturition. Knockout of C/EBPδ in mice delays the onset of labor further supporting the concept. In conclusion, C/EBPδ pathway may be speculated to serve as a potential pharmaceutical target in the amnion for treatment of pre-term labor.

A heretical view: rather than a solely placental protective function, placental 11β hydroxysteroid dehydrogenase 2 also provides substrate for fetal peripheral cortisol synthesis in obese pregnant ewes

Exposure to glucocorticoid levels higher than appropriate for current developmental stages induces offspring metabolic dysfunction. Overfed/obese (OB) ewes and their fetuses display elevated blood cortisol, while fetal Adrenocorticotropic hormone (ACTH) remains unchanged. We hypothesized that OB pregnancies would show increased placental 11β hydroxysteroid dehydrogenase 2 (11β-HSD2) that converts maternal cortisol to fetal cortisone as it crosses the placenta and increased 11β-HSD system components responsible for peripheral tissue cortisol production, providing a mechanism for ACTH-independent increase in circulating fetal cortisol. Control ewes ate 100% National Research Council recommendations (CON) and OB ewes ate 150% CON diet from 60 days before conception until necropsy at day 135 gestation. At necropsy, maternal jugular and umbilical venous blood, fetal liver, perirenal fat, and cotyledonary tissues were harvested. Maternal plasma cortisol and fetal cortisol and cortisone were measured. Fetal liver, perirenal fat, cotyledonary 11β-HSD1, hexose-6-phosphate dehydrogenase (H6PD), and 11β-HSD2 protein abundance were determined by Western blot. Maternal plasma cortisol, fetal plasma cortisol, and cortisone were higher in OB vs. CON (p < 0.01). 11β-HSD2 protein was greater (p < 0.05) in OB cotyledonary tissue than CON. 11β-HSD1 abundance increased (p < 0.05) in OB vs. CON fetal liver and perirenal fat. Fetal H6PD, an 11β-HSD1 cofactor, also increased (p < 0.05) in OB vs. CON perirenal fat and tended to be elevated in OB liver (p < 0.10). Our data provide evidence for increased 11β-HSD system components responsible for peripheral tissue cortisol production in fetal liver and adipose tissue, thereby providing a mechanism for an ACTH-independent increase in circulating fetal cortisol in OB fetuses.

Involvement of STAT3 in the synergistic induction of 11β-HSD1 by SAA1 and cortisol in human amnion fibroblasts

PROBLEM

Cortisol, which is regenerated from biologically inactive cortisone by 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) in human fetal membranes, may play an important role in human parturition. Recently, we have demonstrated that human fetal membranes are capable of de novo synthesis of serum amyloid A1 (SAA1), an acute-phase protein of inflammation, and SAA1 may be engaged in multiple actions associated with human parturition. It remains to be determined whether SAA1 can interact with cortisol in the regulation of 11β-HSD1 in the fetal membranes.

METHOD OF STUDY

In the current study, we examined the regulation of 11β-HSD1 expression by SAA1, and the interaction between SAA1 and cortisol in the regulation of 11β-HSD1 expression in primary human amnion fibroblasts and amnion tissue.

RESULTS

Either SAA1 or cortisol induced 11β-HSD1 expression in a concentration-dependent manner. Combination of SAA1 and cortisol synergistically enhanced 11β-HSD1 expression. Mechanism studies revealed that SAA1 and cortisol induced the phosphorylation of the transcription factor STAT3 in a sequential order with the induction by SAA1 preceding the induction by cortisol. Furthermore, the induction of 11β-HSD1 expression by either SAA1 or cortisol or combination of SAA1 and cortisol was blocked by STAT3 inhibition with its antagonist S3I-201 or siRNA-mediated knockdown.

CONCLUSION

This study has demonstrated that SAA1 and cortisol can reinforce each other in the induction of 11β-HSD1 expression through sequential phosphorylation of STAT3. The synergistic enhancement of 11β-HSD1 expression by SAA1 and cortisol may lead to excessive cortisol accumulation in the fetal membranes at parturition.

H19/miR-30a/C8orf4 axis modulates the adipogenic differentiation process in human adipose tissue-derived mesenchymal stem cells

The adipogenic differentiation of adipose tissue-derived mesenchymal stem cells (ADSCs) is a critical issue in many obesity-related disorders. Cytidine-cytidine-adenosine-adenosine-thymidine (CCAAT) enhancer binding protein α (CEBP-α) and peroxisome proliferator-activated receptor-γ are two important lipogenic and adipogenic transcription factors and markers in adipogenic differentiation. Noncoding RNAs participate in adipogenic differentiation. The long noncoding RNA (lncRNA) H19 is related to multiple cellular differentiation, including adipogenic differentiation; however, its function and precise molecular mechanism in human ADSCs (hADSCs) adipogenic differentiation are unclear. microRNAs that were differentially expressed in adipogenic differentiation and could be targeted by H19 were screened and selected; the regulation and interaction between H19 and miR-30a were verified. The interaction between miR-30a and predicted downstream target C8orf4 was validated. The dynamic effects of H19 and miR-30a on C8orf4 messenger RNA (mRNA) expression and protein and adipogenic differentiation were evaluated. miR-30a negatively regulated H19 with each other through direct binding. As predicted by TargetScan and verified using luciferase reporter gene assays, miR-30a directly bound to the 3'-untranslated region of C8orf4 to inhibit its expression; H19 knockdown suppressed while miR-30a inhibition promoted the mRNA expression and the protein levels of C8orf4 and adipogenic differentiation; the effect of H19 knockdown could be partially reversed by miR-30a inhibition. The lncRNA H19 serves as a competing endogenous RNA (ceRNA) for miR-30a to augment miR-30a downstream target C8orf4, therefore modulating adipogenic differentiation in hADSCs. From the perspective of lncRNA-miRNA-mRNA regulation, we provided a novel regulatory mechanism of hADSCs adipogenic differentiation.

LncRNA TINCR/miR-31-5p/C/EBP-α feedback loop modulates the adipogenic differentiation process in human adipose tissue-derived mesenchymal stem cells

The adipogenic differentiation of adipose tissue-derived mesenchymal stem cells (ADSCs) is a critical issue in many obesity-related disorders and it can be regulated by a crucial transcription factor, CCAAT enhancer binding protein α (C/EBP-α). Apart from, the involvement of non-coding RNAs in adipogenic differentiation has also been reported. As we know, Terminal differentiation-induced ncRNA (TINCR) is required in somatic tissue differentiation. Recently, we found that TINCR could modulate adipogenic differentiation in hADSCs. As predicted by JASPAR and further confirmed by luciferase reporter gene and ChIP assays, C/EBP-α could bind to the promoter region of lncRNA TINCR to activate its expression. Further, miR-31 was confirmed as a direct target of TINCR and could be negatively regulated by TINCR via competing endogenous RNA (ceRNA) mechanism; miR-31 inhibition enhanced the adipogenic differentiation in hADSCs. More importantly, we found that miR-31 directly bound to the 3'-UTR of C/EBP-α to inhibit its expression. Taken together, in hADSCs, lncRNA TINCR, miR-31 and C/EBP-α formed a feedback loop to modulate the adipogenic differentiation process. From the perspective of lncRNA-miRNA-mRNA regulation, we provided a novel regulatory mechanism of hADSCs adipogenic differentiation.

Increased glycogen synthase kinase-3β and hexose-6-phosphate dehydrogenase expression in adipose tissue may contribute to glucocorticoid-induced mouse visceral adiposity

BACKGROUND

Increased adiposity in visceral depots is a crucial feature associated with glucocorticoid (GC) excess. The action of GCs in target tissue is regulated by GC receptor (GR) and 11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD1) coupled with hexose-6-phosphate dehydrogenase (H6pdh). Glycogen synthase kinase-3β (GSK3β) is known to be a crucial mediator of ligand-dependent gene transcription. We hypothesized that the major effects of corticosteroids on adipose fat accumulation are in part medicated by changes in GSK3β and H6pdh.

METHODS

We characterized the alterations of GSK3β and GC metabolic enzymes, and determined the impact of GR antagonist mifepristone on obesity-related genes and the expression of H6pdh and 11ß-HSD1 in adipose tissue of mice exposed to excess GC as well as in in vitro studies using 3T3-L1 adipocytes treated with GCs.

RESULTS

Corticosterone (CORT) exposure increased abdominal fat mass and induced expression of lipid synthase ACC and ACL with activation of GSK3β phosphorylation in abdominal adipose tissue of C57BL/6J mice. Increased pSer⁹ GSK3β was correlated with induction of H6pdh and 11ß-HSD1. Additionally, mifepristone treatment reversed the production of H6pdh and attenuated CORT-mediated production of 11ß-HSD1 and lipogenic gene expression with reduction of pSer⁹ GSK3β, thereby leading to improvement of phenotype of adiposity within adipose tissue in mice treated with excess GCs. Suppression of pSer⁹ GSK3β by mifepristone was accompanied by activation of pThr³⁰⁸ Akt and blockade of CORT-induced adipogenic transcriptor C/EBPα and PPARγ. In addition, mifepristone also attenuated CORT-mediated activation of IRE1α/XBP1. Additionally, reduction of H6pdh by shRNA showed comparable effects to mifepristone on attenuating CORT-induced expression of GC metabolic enzymes and improved lipid accumulation in vitro in 3T3-L1 adipocytes.

CONCLUSION

These findings suggest that elevated adipose GSK3β and H6pdh expression contribute to 11ß-HSD1 mediating hypercortisolism associated with visceral adiposity.

11β-Hydroxysteroid dehydrogenase type 1 shRNA ameliorates glucocorticoid-induced insulin resistance and lipolysis in mouse abdominal adipose tissue

Long-term glucocorticoid exposure increases the risk for developing type 2 diabetes. Prereceptor activation of glucocorticoid availability in target tissue by 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) coupled with hexose-6-phosphate dehydrogenase (H6PDH) is an important mediator of the metabolic syndrome. We explored whether the tissue-specific modulation of 11β-HSD1 and H6PDH in adipose tissue mediates glucocorticoid-induced insulin resistance and lipolysis and analyzed the effects of 11β-HSD1 inhibition on the key lipid metabolism genes and insulin-signaling cascade. We observed that corticosterone (CORT) treatment increased expression of 11β-HSD1 and H6PDH and induced lipase HSL and ATGL with suppression of p-Thr(172) AMPK in adipose tissue of C57BL/6J mice. In contrast, CORT induced adipose insulin resistance, as reflected by a marked decrease in IR and IRS-1 gene expression with a reduction in p-Thr(308) Akt/PKB. Furthermore, 11β-HSD1 shRNA attenuated CORT-induced 11β-HSD1 and lipase expression and improved insulin sensitivity with a concomitant stimulation of pThr(308) Akt/PKB and p-Thr(172) AMPK within adipose tissue. Addition of CORT to 3T3-L1 adipocytes enhanced 11β-HSD1 and H6PDH and impaired p-Thr(308) Akt/PKB, leading to lipolysis. Knockdown of 11β-HSD1 by shRNA attenuated CORT-induced lipolysis and reversed CORT-mediated inhibition of pThr(172) AMPK, which was accompanied by a parallel improvement of insulin signaling response in these cells. These findings suggest that elevated adipose 11β-HSD1 expression may contribute to glucocorticoid-induced insulin resistance and adipolysis.

Transgenic overexpression of hexose-6-phosphate dehydrogenase in adipose tissue causes local glucocorticoid amplification and lipolysis in male mice

The prereceptor activation of glucocorticoid production in adipose tissue by NADPH-dependent 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) has emerged as a potential mechanism in the pathogenesis of visceral obesity and metabolic syndrome. Hexose-6-phosphate dehydrogenase (H6PDH) is an endoplasmic reticulum lumen-resident enzyme that generates cofactor NADPH and thus mediates 11β-HSD1 activity. To determine the role of adipose H6PDH in the prereceptor modulation of 11β-HSD1 and metabolic phenotypes, we generated a transgenic (Tg) mouse model overexpressing H6PDH under the control of the enhancer-promoter region of the adipocyte fatty acid-binding protein (aP2) gene (aP2/H6PDH Tg mice). Transgenic aP2/H6PDH mice exhibited relatively high expression of H6PDH and elevated corticosterone production with induction of 11β-HSD1 activity in adipose tissue. This increase in corticosterone production in aP2-H6PDH Tg mice resulted in mild abdominal fat accumulation with induction of C/EBP mRNA expression and slight weight gain. Transgenic aP2/H6PDH mice also exhibited fasting hyperglycemia and glucose intolerance with insulin resistance. In addition, the aP2/H6PDH Tg mice have elevated circulating free fatty acid levels with a concomitant increased adipose lipolytic action associated with elevated HSL mRNA and Ser(660) HSL phosphorylation within abdominal fat. These results suggest that increased H6PDH expression specifically in adipose tissue is sufficient to cause intra-adipose glucocorticoid production and adverse metabolic phenotypes. These findings suggest that the aP2/H6PDH Tg mice may provide a favorable model for studying the potential impact of H6PDH in the pathogenesis of human metabolic syndrome.

Mechanism of repression of 11β-hydroxysteroid dehydrogenase type 1 by growth hormone in 3T3-L1 adipocytes

11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1) is an NADPH-dependent reductase that converts cortisone to cortisol in adipose tissue. We previously reported that GH and IGF-I decrease 11β-HSD1 activity and mRNA levels in adipocytes. Hexose-6-phosphate dehydrogenase (H6PDH) is involved in the production of NADPH, which is a coenzyme for 11β-HSD1. The aim of the present study was to clarify further the mechanism of repression of 11β-HSD1 activity by GH using linsitinib, an IGF-I receptor inhibitor. The suppression of 11β-HSD1 mRNA by IGF-I was attenuated in the presence of 1 μM linsitinib (17.2% vs. 53.3% of basal level, P<0.05). 11β-HSD1 mRNA levels in cells treated with GH in the presence of 1 μM linsitinib were not different from those in absence of linsitinib (35.9% vs. 33.9%). The increase in IGF-I mRNA levels with GH and 1 μM linsitinib was not different from that in the absence of linsitinib (359% vs. 347%). H6PDH mRNA levels were significantly decreased in cells treated with IGF-I for 8 and 24 h (55.6% and 33.7%, P<0.05). In the presence of 1 μM linsitinib, there was no repression of H6PDH mRNA (111.4%). H6PDH mRNA levels were significantly decreased in cells treated with GH in the absence of linsitinib for 24 h (55.9%, P<0.05), but not for 8 h (89.5%). The presence of 1 μM linsitinib also prevented repression of H6PDH mRNA by GH over 24 h (107.8%). These results suggest that GH directly represses 11β-HSD1 mRNA rather than acting via the IGF-I receptor, and that GH represses H6PDH through locally produced IGF-I.

Proinflammatory cytokine induction of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) in human adipocytes is mediated by MEK, C/EBPβ, and NF-κB/RelA

CONTEXT

Levels of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1), which regenerates active glucocorticoids, are selectively elevated in adipose tissue in human obesity and metabolic syndrome, both conditions associated with chronic low-grade inflammation. 11β-HSD1 expression is induced by proinflammatory cytokines in a variety of cell types, including in human adipocytes differentiated in vitro.

OBJECTIVE

Our objective was to determine the mechanisms by which proinflammatory cytokines induce 11β-HSD1 in human adipocytes.

RESULTS

The proinflammatory cytokines IL-1α (10 ng/mL) and TNFα (20 ng/mL) increased 11β-HSD1 mRNA levels in human primary adipocyte fractions and Simpson-Golabi-Behmel syndrome (SGBS) adipocytes (P<.001). Inhibition of the MAPK/ERK kinase (MEK) attenuated CCAAT/enhancer binding protein (C/EBP) β phosphorylation at Thr235 and IL-1α/TNFα induction of 11β-HSD1 (P≤.007). The small interfering RNA-mediated knockdown of C/EBPβ and nuclear factor (NF)-κB/RelA or inhibition of NF-κB/RelA also attenuated cytokine induction of 11β-HSD1 (P≤.001). Moreover, induction of 11β-HSD1 by IL-1α in SGBS cells was associated with nuclear localization of C/EBPβ and NF-κB/RelA. Chromatin immunoprecipitation experiments showed C/EBPβ and NF-κB/RelA located to the 11β-HSD1 promoter in human adipose tissue. Treatment of adipocyte fractions or SGBS adipocytes with metformin or acetylsalicylic acid, which target C/EBPβ and NF-κB/RelA signaling, attenuated the IL-1α induction of 11β-HSD1 (P≤.002).

CONCLUSIONS

Increased proinflammatory signaling in inflamed adipose tissue may mediate elevated 11β-HSD1 expression at this site via MEK, C/EBPβ, and NF-κB/RelA. These molecules/signaling pathways are, therefore, potential targets for drugs, including metformin and acetylsalicylic acid, to prevent/decreased up-regulation of 11β-HSD1 in human obese/metabolic syndrome adipose tissue.

11β-hydroxysteroid dehydrogenases: intracellular gate-keepers of tissue glucocorticoid action

Glucocorticoid action on target tissues is determined by the density of "nuclear" receptors and intracellular metabolism by the two isozymes of 11β-hydroxysteroid dehydrogenase (11β-HSD) which catalyze interconversion of active cortisol and corticosterone with inert cortisone and 11-dehydrocorticosterone. 11β-HSD type 1, a predominant reductase in most intact cells, catalyzes the regeneration of active glucocorticoids, thus amplifying cellular action. 11β-HSD1 is widely expressed in liver, adipose tissue, muscle, pancreatic islets, adult brain, inflammatory cells, and gonads. 11β-HSD1 is selectively elevated in adipose tissue in obesity where it contributes to metabolic complications. Similarly, 11β-HSD1 is elevated in the ageing brain where it exacerbates glucocorticoid-associated cognitive decline. Deficiency or selective inhibition of 11β-HSD1 improves multiple metabolic syndrome parameters in rodent models and human clinical trials and similarly improves cognitive function with ageing. The efficacy of inhibitors in human therapy remains unclear. 11β-HSD2 is a high-affinity dehydrogenase that inactivates glucocorticoids. In the distal nephron, 11β-HSD2 ensures that only aldosterone is an agonist at mineralocorticoid receptors (MR). 11β-HSD2 inhibition or genetic deficiency causes apparent mineralocorticoid excess and hypertension due to inappropriate glucocorticoid activation of renal MR. The placenta and fetus also highly express 11β-HSD2 which, by inactivating glucocorticoids, prevents premature maturation of fetal tissues and consequent developmental "programming." The role of 11β-HSD2 as a marker of programming is being explored. The 11β-HSDs thus illuminate the emerging biology of intracrine control, afford important insights into human pathogenesis, and offer new tissue-restricted therapeutic avenues.

Pro-inflammatory cytokine induction of 11β-hydroxysteroid dehydrogenase type 1 in A549 cells requires phosphorylation of C/EBPβ at Thr235

11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) converts inert glucocorticoids into active forms, thereby increasing intracellular glucocorticoid levels, important to restrain acute inflammation. 11β-HSD1 is induced by pro-inflammatory cytokines in a variety of cells. Here, we show 11β-HSD1 expression in human A549 epithelial cells is increased by pro-inflammatory cytokines (IL-1α/TNFα) via the P2 promoter of the HSD11B1 gene. Inhibition of p38 MAPK attenuated the pro-inflammatory cytokine induction of mRNA encoding 11β-HSD1 as well as that encoding C/EBPβ. IL-1α/TNFα-induced phosphorylation of C/EBPβ at Thr235 was also attenuated by p38 MAPK inhibition suggesting involvement of a p38 MAPK-C/EBPβ pathway. siRNA-mediated knock-down of C/EBPβ and NF-κB/RelA implicated both transcription factors in the IL-1α/TNFα induction of HSD11B1 mRNA. Transient transfections of HSD11B1 promoter-reporter constructs identified the proximal region of the P2 promoter of HSD11B1 as essential for this induction. IL-1α increased binding of C/EBPβ to the HSD11B1 P2 promoter, but this was not observed for NF-κB/RelA, suggesting indirect regulation by NF-κB/RelA. Ectopic expression of mutant chicken C/EBPβ constructs unable to undergo phosphorylation at the threonine equivalent to Thr235 attenuated the IL-1α-induction of HSD11B1, whereas mimicking constitutive phosphorylation of Thr235 (by mutation to aspartate) increased basal expression of HSD11B1 mRNA without affecting IL-1α-induced levels. These data clearly demonstrate a role for both C/EBPβ and NF-κB/RelA in the pro-inflammatory cytokine induction of HSD11B1 in human epithelial cells and show that p38 MAPK-induced phosphorylation of C/EBPβ at Thr235 is critical in this.

Changing glucocorticoid action: 11β-hydroxysteroid dehydrogenase type 1 in acute and chronic inflammation

Since the discovery of cortisone in the 1940s and its early success in treatment of rheumatoid arthritis, glucocorticoids have remained the mainstay of anti-inflammatory therapies. However, cortisone itself is intrinsically inert. To be effective, it requires conversion to cortisol, the active glucocorticoid, by the enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1). Despite the identification of 11β-HSD in liver in 1953 (which we now know to be 11β-HSD1), its physiological role has been little explored until recently. Over the past decade, however, it has become apparent that 11β-HSD1 plays an important role in shaping endogenous glucocorticoid action. Acute inflammation is more severe with 11β-HSD1-deficiency or inhibition, yet in some inflammatory settings such as obesity or diabetes, 11β-HSD1-deficiency/inhibition is beneficial, reducing inflammation. Current evidence suggests both beneficial and detrimental effects may result from 11β-HSD1 inhibition in chronic inflammatory disease. Here we review recent evidence pertaining to the role of 11β-HSD1 in inflammation. This article is part of a Special Issue entitled 'CSR 2013'.

Duplicated CCAAT/enhancer-binding protein β (C/EBPβ) gene: transcription and methylation changes in response to dietary betaine in Landes goose liver

The CCAAT/enhancer-binding protein β gene (C/EBPβ) is one of the key regulating factors of lipid metabolic balance in the liver. To better understand how C/EBPβ affects lipid accumulation in the Landes goose liver, its DNA was cloned. The goose C/EBPβ DNA sequence (2,075 bp) contains a 984-bp open reading frame and part of the 5'-flanking region, and shares 96.66 and 62.07% similarity with the chicken and human sequences at the amino acid level, respectively. Tissue expression profiling showed that the relative expression level was high in the liver and adipose tissue. To understand the effect of betaine on C/EBPβ in goose liver, the relative expression levels of C/EBPβ were detected under different treatments. Compared with the control group, C/EBPβ expression increased in the high-carbohydrate group (P < 0.01) and decreased in the betaine treatment group (P > 0.05). Using bisulfite sequencing PCR, the gene methylation status was analyzed among the different treatment groups. None of the 54 CpG sites in the promoter region or the 28 CpG sites in the structural domain of the coding region showed any significantly different methylation patterns among the groups. Taken together, the results showed that betaine decreased the goose C/EBPβ gene expression, but did not directly regulate its methylation. The data may form the basis for further investigation of the mechanisms of the effect of C/EBPβ on the regulation of lipometabolism in the goose liver and the effect of betaine on lipid metabolic genes at the molecular level.

Evidence for transcript-specific epigenetic regulation of glucocorticoid-stimulated skeletal muscle 11β-hydroxysteroid dehydrogenase-1 activity in type 2 diabetes

BACKGROUND

The enzyme 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1) converts inactive cortisone into active cortisol in insulin target tissues. In people with type 2 diabetes, skeletal muscle (SkM) 11βHSD1 is upregulated by the potent glucocorticoid dexamethasone. The HSD11B1 gene has two promoters designated P1 and P2. CCAAT/enhancer-binding protein beta (C/EBPβ) is known to regulate expression of 11βHSD1 via the P2 promoter. In this study, we investigated the potential role of altered DNA methylation of the P1 and P2 promoters in the observed dexamethasone-induced upregulation of SkM 11βHSD1 oxoreductase activity in human diabetic subjects. SkM biopsies from 15 people with type 2 diabetes were collected before and after treatment with oral dexamethasone 4 mg/day for 4 days and SkM 11βHSD1, C/EBPβ and P1 and P2 promoter region mRNA levels were measured by quantitative RT-PCR. 11βHSD1 oxoreductase activity was quantified by measuring the conversion of radiolabeled 3H-cortisone to cortisol by thin layer chromatography. Analysis of HSD11B1 promoter methylation (P1 and P2) was performed using Sequenom MassARRAY EpiTYPER analysis.

RESULTS

Dexamethasone treatment resulted in a significant increase in 11βHSD1 mRNA levels (P = 0.003), oxoreductase activity (P = 0.017) and C/EBPβ mRNA (P = 0.015), and increased expression of both the P1 (P = 0.008) and P2 (P = 0.016) promoter regions . The distal P1 promoter region showed a significant reduction in methylation following dexamethasone (P = 0.026). There was a significant negative correlation between the change in methylation at this site and the increment in 11βHSD1 oxoreductase activity (r = -0.62, P = 0.014).

CONCLUSIONS

Our findings of reduced methylation in the HSD11B1 P1 promoter in association with increased 11βHSD1 oxoreductase activity implicate complex multi-promoter epigenetic mechanisms in the regulation of 11βHSD1 levels in SkM.

The rs4844880 polymorphism in the promoter region of the HSD11B1 gene associates with bone mineral density in healthy and postmenopausal osteoporotic women

INTRODUCTION

The 11β-hydroxysteroid dehydrogenase type 1 enzyme (11β-HSD1) plays an important role in the regulation of local glucocorticoid concentration in a tissue specific manner. Previous studies indicated associations between polymorphisms (SNPs) of the HSD11B1 gene and laboratory as well as osteodensitometric parameters of bone metabolism. In our present work we examined whether the tagging HSD11B1 gene polymorphisms could influence bone metabolism in healthy and postmenopausal osteoporotic women.

EXPERIMENTAL

HapMap database was used for identification and selection of SNPs located in the 38kb range of the HSD11B1 gene. Twelve SNPs were selected and genotyped in 209 healthy control women using Taqman SNP assays on Real-Time PCR and direct DNA sequencing. Of these SNPs, the rs4844880 was genotyped in 154 women with postmenopausal osteoporosis. Functional characterization of the rs4844880 was performed by in vitro luciferase assay.

RESULTS

One of the 12 HSD11B1 SNPs, the rs4844880 showed a significant association with higher bone mineral density and/or T- and Z-scores at lumbar spine in healthy women. When data from 154 postmenopausal osteoporotic women were compared to those obtained from 101 age-matched postmenopausal healthy women selected from our healthy control group this association was strongly significant at the femoral neck region. In vitro luciferase assay demonstrated that the polymorphic rs4844880 allele inhibited the luciferase activity more significantly than the major allele.

CONCLUSIONS

The rs4844880 polymorphism in the promoter region of the HSD11B1 gene resulting in a reduced expression of the enzyme may exert a beneficial effect on bone in healthy and postmenopausal osteoporotic women.

Regulation of adipocyte 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) by CCAAT/enhancer-binding protein (C/EBP) β isoforms, LIP and LAP

11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) catalyses intracellular regeneration of active glucocorticoids, notably in liver and adipose tissue. 11β-HSD1 is increased selectively in adipose tissue in human obesity, a change implicated in the pathogenesis of metabolic syndrome. With high fat (HF)-feeding, adipose tissue 11β-HSD1 is down-regulated in mice, plausibly to counteract metabolic disease. Transcription of 11β-HSD1 is directly regulated by members of the CCAAT/enhancer binding protein (C/EBP) family. Here we show that while total C/EBPβ in adipose tissue is unaltered by HF diet, the ratio of the C/EBPβ isoforms liver-enriched inhibitor protein (LIP) and liver-enriched activator protein (LAP) (C/EBPβ-LIP:LAP) is increased in subcutaneous adipose. This may cause changes in 11β-HSD1 expression since genetically modified C/EBPβ^(+/L) mice, with increased C/EBPβ-LIP:LAP ratio, have decreased subcutaneous adipose 11β-HSD1 mRNA levels, whereas C/EBPβ^ΔuORF mice, with decreased C/EBPβ-LIP:LAP ratio, show increased subcutaneous adipose 11β-HSD1. C/EBPβ-LIP:LAP ratio is regulated by endoplasmic reticulum (ER) stress and mTOR signalling, both of which are altered in obesity. In 3T3-L1 adipocytes, 11β-HSD1 mRNA levels were down-regulated following induction of ER stress by tunicamycin but were up-regulated following inhibition of mTOR by rapamycin. These data point to a central role for C/EBPβ and its processing to LIP and LAP in transcriptional regulation of 11β-HSD1 in adipose tissue. Down-regulation of 11β-HSD1 by increased C/EBPβ-LIP:LAP in adipocytes may be part of a nutrient-sensing mechanism counteracting nutritional stress generated by HF diet.

Central glucocorticoid administration promotes weight gain and increased 11β-hydroxysteroid dehydrogenase type 1 expression in white adipose tissue

Glucocorticoids (GCs) are involved in multiple metabolic processes, including the regulation of insulin sensitivity and adipogenesis. Their action partly depends on their intracellular activation by 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1). We previously demonstrated that central GC administration promotes hyperphagia, body weight gain, hyperinsulinemia and marked insulin resistance at the level of skeletal muscles. Similar dysfunctions have been reported to occur upon specific overexpression of 11β-HSD1 in adipose tissue. The aim of the present study was therefore to determine whether the effects of central GC infusion may enhance local GC activation in white adipose tissue. Male Wistar and Sprague Dawley (SD) rats were intracerebroventricularly infused with GCs for 2 to 3 days. Body weight, food intake and metabolic parameters were measured, and expression of enzymes regulating 11β-HSD1, as well as that of genes regulated by GCs, were quantified. Central GC administration induced a significant increase in body weight gain and in 11β-HSD1 and resistin expression in adipose tissue. A decrease 11β-HSD1 expression was noticed in the liver of SD rats, as a partial compensatory mechanism. Such effects of GCs are centrally elicited. This model of icv dexamethasone infusion thus appears to be a valuable acute model, that helps delineating the initial metabolic defects occurring in obesity. An impaired downregulation of intracellular GC activation in adipose tissue may be important for the development of insulin resistance.

Peroxisome proliferator-activated receptor-γ stimulates 11β-hydroxysteroid dehydrogenase type 1 in rat vascular smooth muscle cells

Glucocorticoids are metabolized in vascular tissue by two types of 11β-hydroxysteroid dehydrogenases (11HSD1, 11HSD2) and thus these enzymes are considered to be important factors that modulate the diverse and complex effects of glucocorticoids on cardiovascular function. The present study evaluated the effect of peroxisome proliferator-activated receptor-γ (PPARγ) agonist pioglitazone on 11HSD1 vascular smooth muscle cells (VSMC) and compared the effect with that of corticosterone. Using primary cultures of VSMC derived from rat aorta, we showed that pioglitazone significantly increases 11HSD1 activity and mRNA expression in a dose-dependent manner with EC(50) 243 nM and that this effect is not blocked by RU 486, an antagonist of the glucocorticoid receptor. In contrast, corticosterone had no effect on 11HSD1. Pioglitazone positively regulated transcription of two CCAAT/enhancer-binding proteins (C/EBPs), specifically C/EBPα a potent activator of 11HSD1 gene transcription in some cells types, and C/EBPζ, whereas C/EBPβ and C/EBPδ were not changed. In contrast, corticosterone stimulated the expression of C/EBPβ and C/EBPδ, but the levels of C/EBPα and C/EBPζ were not changed. In conclusion, activation of PPARγ in VSMC up-regulates vascular 11HSD1 and thus reactivates 11-oxo metabolites to biologically active glucocorticoids through a mechanism that seems to involve C/EBPα and C/EBPζ. Our data provide one of the possible explanations for PPARγ agonists' effects on the cardiovascular system.

The anti-inflammatory and immunosuppressive effects of glucocorticoids, recent developments and mechanistic insights

Since the discovery of glucocorticoids in the 1940s and the recognition of their anti-inflammatory effects, they have been amongst the most widely used and effective treatments to control inflammatory and autoimmune diseases. However, their clinical efficacy is compromised by the metabolic effects of long-term treatment, which include osteoporosis, hypertension, dyslipidaemia and insulin resistance/type 2 diabetes mellitus. In recent years, a great deal of effort has been invested in identifying compounds that separate the beneficial anti-inflammatory effects from the adverse metabolic effects of glucocorticoids, with limited effect. It is clear that for these efforts to be effective, a greater understanding is required of the mechanisms by which glucocorticoids exert their anti-inflammatory and immunosuppressive actions. Recent research is shedding new light on some of these mechanisms and has produced some surprising new findings. Some of these recent developments are reviewed here.

Reciprocal regulation of 11β-hydroxysteroid dehydrogenase 1 and glucocorticoid receptor expression by dexamethasone inhibits human coronary artery smooth muscle cell proliferation in vitro

The actions of glucocorticoids are mediated, in part, by 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1), which amplifies their effects at the pre-receptor level by converting cortisone to cortisol. Glucocorticoids, such as dexamethasone, inhibit vascular smooth muscle cell proliferation; however, the role of 11β-HSD1 in this response remains unknown. Accordingly, we treated human coronary artery smooth muscle cells (HCSMC) with dexamethasone (10(-9)-10(-6) mol/l) and found that after 72 h dexamethasone increased 11β-HSD1 expression (14.16 ± 1.6-fold, P < 0.001) and activity (6.21 ± 1.2-fold, P < 0.001) in a dose- and time-dependent manner, which was dependent upon glucocorticoid receptor (GR) activation and C/EBPβ and C/EBPδ signaling. As glucocorticoids are known to negatively regulate GR expression, we examined the effect of decreasing 11β-HSD1 expression on GR expression. In HCSMC transfected with 11β-HSD1 siRNA, GR expression was increased; this effect was associated with protein kinase A activation and CREB phosphorylation. To examine the role of 11β-HSD1 in HCSMC proliferation, we decreased 11β-HSD1 expression and stimulated cells with platelet-derived growth factor (PDGF) (10 ng/ml). Decreased 11β-HSD1 expression was associated with increased cell proliferation in the absence of PDGF compared to scrambled control-transfected cells (236.10 ± 13.11%, n = 4, P < 0.001) and this effect was augmented by PDGF. Furthermore, the inhibitory effect of dexamethasone on cellular proliferation was abrogated in 11β-HSD1 siRNA-transfected HCSMC. Downregulation of 11β-HSD1 was associated with decreased p27(kip1) expression and increased phosphorylated retinoblastoma protein, consistent with a proliferative response. These findings suggest that 11β-HSD1 plays a role in the effects of glucocorticoids on vascular smooth muscle cell phenotype.

11beta-Hydroxysteroid dehydrogenase type 1 is an important regulator at the interface of obesity and inflammation

Systemic glucocorticoid excess, as exemplified by the Cushing syndrome, leads to obesity and all further symptoms of the metabolic syndrome. The current obesity epidemic, however, is not characterized by increased plasma cortisol concentrations, but instead comes along with chronic low-grade inflammation in adipose tissue and concomitant increased levels of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1, gene HSD11B1), a parameter known to cause obesity in a mouse model. 11beta-HSD1 represents an intracellular amplifier of active glucocorticoid, thus enhances the associated effects on the inflammatory response as well as on nutrient and energy metabolism, and may therefore cause and exacerbate obesity by local increase of glucocorticoid concentrations. Obtained by extensive literature and database searching, the present review includes comprehensive lists of primary glucocorticoid-sensitive genes and gene products as well as of the thus far known regulators of HSD11B1 expression with implication in inflammation and metabolic disease. Collectively, the data clearly show that, in addition to amplifying active glucocorticoid and thus profoundly modulating inflammation and nutrient metabolism, 11beta-HSD1 is subject to tight control of multiple additional immunomodulatory and metabolic regulators. Hence, 11beta-HSD1 acts at the interface of inflammation and obesity and represents an efficient integrator and effector of local inflammatory and metabolic state.

Expression of miR-31, miR-125b-5p, and miR-326 in the adipogenic differentiation process of adipose-derived stem cells

MicroRNAs (miRNAs) are small single-stranded RNAs of 19-22 nucleotides (nt) and are important posttranscriptional regulation of genes. A link between miRNA function and cancer was researched by the miRNAs microarray technology recently. However, during adipogenic differentiation of ADSCs process, this technology was less used to study adipogenic differentiation mechanism of ADSCs. In this study, miRNA microarray technology was used to examine the expression of miRNA that were differences between induced group and noninduced group of ADSC adipogenic differentiation. Real-time quantitative PCR (real-time qPCR) was used to quantify the miRNA expression. The TargetScan 5.0 software was used to find their target genes. Our results showed that the expression of rno-miR-31, rno-miR-125b-5p, and rno-miR-326 were downregulation in the adipogenic differentiation process. By the statistic analysis, this study showed that the expression of rno-miR-31 and rno-miR-326 were significantly deregulation. In addition, the target genes of rno-miR-31 and rno-miR-326 were correlated with the adipogenic differentiation. Our study suggested that the expression of rno-miR-31 and rno-miR-326 were involved in the adipogenic differentiation process.

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

Cortisone, a glucocorticoid hormone, was first used to treat rheumatoid arthritis in humans in the late 1940s, for which Hench, Reichstein and Kendall were awarded a Nobel Prize in 1950 and which led to the discovery of the anti-inflammatory effects of glucocorticoids. To be effective, the intrinsically inert cortisone must be converted to the active glucocorticoid, cortisol, by the intracellular action of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). Whilst orally administered cortisone is rapidly converted to the active hormone, cortisol, by first pass metabolism in the liver, recent work has highlighted an anti-inflammatory role for 11beta-HSD1 within specific tissues, including in leukocytes. Here, we review recent evidence pertaining to the anti-inflammatory role of 11beta-HSD1 and describe how inhibition of 11beta-HSD1, as widely proposed for treatment of metabolic disease, may impact upon inflammation. Finally, the mechanisms that regulate 11beta-HSD1 transcription will be discussed.

Tumor necrosis factor-alpha upregulates 11beta-hydroxysteroid dehydrogenase type 1 expression by CCAAT/enhancer binding protein-beta in HepG2 cells

The enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) catalyzes the conversion of inactive to active glucocorticoids. 11beta-HSD1 plays a crucial role in the pathogenesis of obesity and controls glucocorticoid actions in inflammation. Several studies have demonstrated that TNF-alpha increases 11beta-HSD1 mRNA and activity in various cell models. Here, we demonstrate that mRNA and activity of 11beta-HSD1 is increased in liver tissue from transgenic mice overexpressing TNF-alpha, indicating that this effect also occurs in vivo. To dissect the molecular mechanism of this increase, we investigated basal and TNF-alpha-induced transcription of the 11beta-HSD1 gene (HSD11B1) in HepG2 cells. We found that TNF-alpha acts via p38 MAPK pathway. Transient transfections with variable lengths of human HSD11B1 promoter revealed highest activity with or without TNF-alpha in the proximal promoter region (-180 to +74). Cotransfection with human CCAAT/enhancer binding protein-alpha (C/EBPalpha) and C/EBPbeta-LAP expression vectors activated the HSD11B1 promoter with the strongest effect within the same region. Gel shift and RNA interference assays revealed the involvement of mainly C/EBPalpha, but also C/EBPbeta, in basal and only of C/EBPbeta in the TNF-alpha-induced HSD11B1 expression. Chromatin immunoprecipitation assay confirmed in vivo the increased abundance of C/EBPbeta on the proximal HSD11B1 promoter upon TNF-alpha treatment. In conclusion, C/EBPalpha and C/EBPbeta control basal transcription, and TNF-alpha upregulates 11beta-HSD1, most likely by p38 MAPK-mediated increased binding of C/EBPbeta to the human HSD11B1 promoter. To our knowledge, this is the first study showing involvement of p38 MAPK in the TNF-alpha-mediated 11beta-HSD1 regulation, and that TNF-alpha stimulates enzyme activity in vivo.

Growth hormone (GH) or insulin-like growth factor (IGF)-I represses 11beta-hydroxysteroid dehydrogenase type 1 (HSD1) mRNA expression in 3T3-L1 cells and its activity in their homogenates

Patients with growth hormone (GH) deficiency (GHD) have a clinical feature of visceral adiposity and it has been reported that these patients have an increased active cortisol (F)/inactive cortisone (E) metabolite ratio. 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) is an enzyme expressed in liver and adipose tissue that acts principally as a reductase converting E to F. In the present study, we investigated the effects of GH or IGF-I on the activity of 11beta- HSD1 in 3T3-L1 cell homogenates and its mRNA expression. First, we showed that 11beta-HSD1 activity and mRNA levels were low in preadipocytes and increased throughout the process of adipogenesis. When fully differentiated adipocytes were treated with GH for various times, the activity of 11beta-HSD1 was significantly decreased after 4 h and 8 h but was restored to basal levels after 24 h. After 8 h of GH stimulation, 11beta-HSD1 mRNA levels were decreased compared with basal levels. IGF-I treatment of adipocytes resulted in rapid decreases in 11beta-HSD1 activity as well as mRNA levels; however, IGF-I treatment for 24 h increased 11beta-HSD1 activity. In long-term cultured adipocytes, GH or IGF-I showed only inhibitory effects on 11beta-HSD1 activity. In conclusion, 11beta-HSD1 activity was suppressed by GH or IGF-I in differentiated adipocytes, probably due to a reduction of 11beta-HSD1 mRNA levels. These data suggest that under the conditions of low GH or IGF-I concentrations, 11beta-HSD1 activity in adipose tissue is maintained at high levels, leading to an increase in active cortisol that induces adipogenesis and/or lipogenesis. Thus, visceral adiposity in patients with GHD might be related to increased 11beta-HSD1 activity.

Expression of 11beta-hydroxysteroid dehydrogenase type 1 in human fetal lung and regulation of its expression by interleukin-1beta and cortisol

CONTEXT

Glucocorticoids are crucial in fetal lung function. The amount of cortisol available to its receptors is increased by 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). Glucocorticoids and IL-1beta are known to induce 11beta-HSD1 expression in a number of tissues, but controversial results were obtained with regard to 11beta-HSD1 expression in human fetal lung.

OBJECTIVE

We examined the expression of 11beta-HSD1 and its regulation by cortisol and IL-1beta in human fetal lung.

RESULTS

Immunohistochemistry revealed 11beta-HSD1 expression in the epithelium and mesenchymal layer of the small bronchus and bronchiole of human fetal lung at 8 months but not at 4 months gestation, which was confirmed by PCR revealing 11beta-HSD1 mRNA expression in the fetal lung tissue. By using a cell line derived from human fetal lung fibroblasts, we demonstrated that cortisol (10(-5) to 10(-3) mmol/liter) or IL-1beta (0.1 to 10 ng/ml) induced 11beta-HSD1 mRNA expression in a concentration-dependent manner. The induction of 11beta-HSD1 by IL-1beta was further increased by cortisol, whereas the induction of cyclooxygenase 2 by IL-1beta was inhibited by cortisol. Nuclear factor kappaB activation inhibitor could only block the induction of cyclooxygenase 2 but not 11beta-HSD1 by IL-1beta, suggesting that different mechanisms were utilized by IL-1beta in the regulation of 11beta-HSD1 versus proinflammatory mediators. Global inhibition of CCAAT-enhancer-binding proteins (C/EBPs) with transfection of C/EBP-specific dominant-negative expression plasmid could attenuate the induction of 11beta-HSD1 by IL-1beta, suggesting that C/EBPs may mediate the induction of 11beta-HSD1 by IL-1beta.

CONCLUSIONS

11beta-HSD1 is expressed in human fetal lung; cortisol and IL-1beta could synergistically induce its expression.

Insulin and dexamethasone dynamically regulate adipocyte 11beta-hydroxysteroid dehydrogenase type 1

The adipocyte enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) amplifies local glucocorticoid action by generating active glucocorticoids from inactive metabolites and has emerged as a key player in the pathogenesis of central obesity and metabolic syndrome. However, the regulation of adipocyte 11beta-HSD1 is incompletely understood. Therefore, the present study was designed to investigate the effects of insulin and glucocorticoid as well as their underlying molecular mechanisms on 11beta-HSD1 activity and expression in 3T3-L1 adipocytes and determine whether the in vitro findings could be confirmed in vivo. Our main in vitro findings are 1) insulin stimulated whereas dexamethasone inhibited 11beta-HSD1 activity and expression in a time- and concentration-dependent manner; 2) the effect of dexamethasone was mimicked by both cortisol and corticosterone but blocked by the glucocorticoid receptor antagonist RU486; 3) the p38 MAPK inhibitor SB220025, but not the ERK inhibitor U0126 or the phosphatidylinositol 3-kinase inhibitor LY294002, prevented insulin stimulation of 11beta-HSD1 activity; and 4) although dexamethasone did not alter the half-life of 11beta-HSD1 mRNA, insulin doubled it. Taken together, these in vitro results demonstrate that insulin stimulates adipocyte 11beta-HSD1 through a posttranscriptional mechanism that involves activation of the p38 MAPK signaling pathway, whereas dexamethasone exerts an opposite effect by a glucocorticoid receptor-mediated transcriptional mechanism. In contrast, both insulin and dexamethasone augmented 11beta-HSD1 activity and expression in rat white adipose tissue in vivo, thus confirming the role of insulin but revealing a fundamental difference regarding the role of dexamethasone in regulating adipocyte 11beta-HSD1 between the two model systems.

Glucocorticoid regulation of the promoter of 11beta-hydroxysteroid dehydrogenase type 1 is indirect and requires CCAAT/enhancer-binding protein-beta

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.

Postnatal programming of glucocorticoid metabolism in rats modulates high-fat diet-induced regulation of visceral adipose tissue glucocorticoid exposure and sensitivity and adiponectin and proinflammatory adipokines gene expression in adulthood

OBJECTIVE

Alterations of the perinatal environment, which lead to increased prevalence of the metabolic syndrome in adulthood, program an upregulation of systemic and/or adipose tissue glucocorticoid metabolism (11 beta-hydroxysteroid dehydrogenase type 1 [11 beta-HSD-1]-induced corticosterone reactivation). We hypothesized that postnatal programming could modulate high-fat diet-induced adipose tissue dysregulation in adulthood.

RESEARCH DESIGN AND METHODS

We compared the effects of chronic (since weaning) high- or low-fat diet in postnatally normofed (control) or overfed (programmed) rats.

RESULTS

Postnatal programming accentuated high-fat diet-induced overweight, insulin resistance, glucose intolerance, and decrease in circulating and epididymal adipose tissue adiponectin. Neither manipulation altered liver function. Postnatal programming or high-fat diet increased systemic corticosterone production, which was not further modified when both manipulations were associated. Postnatal programming suppressed high-fat diet-induced decrease in mesenteric adipose tissue (MAT) glucocorticoid sensitivity and triggered high-fat diet-induced increase in MAT glucocorticoid exposure, subsequent to enhanced MAT 11 beta-HSD-1 gene expression. MAT tumor necrosis factor (TNF)-alpha, TNF-receptor 1, interleukin (IL)-6, resistin, and plasminogen activator inhibitor-1 mRNAs were not changed by high-fat feeding in control rats and showed a large increase in programmed animals, with this effect further enhanced by high-fat diet for TNF-alpha and IL-6.

CONCLUSIONS

Our data show for the first time that postnatal manipulation programs high-fat diet-induced upregulation of MAT glucocorticoid exposure, sensitivity, and inflammatory status and therefore reveal the pivotal role of the environment during the perinatal period on the development of diet-induced adipose tissue dysregulation in adulthood. They also urge the need for clinical trials with specific 11 beta-HSD-1 inhibitors.

DHEA induces 11 -HSD2 by acting on CCAAT/enhancer-binding proteins

11beta-Hydroxysteroid dehydrogenase (11beta-HSD) type 1 and type 2 catalyze the interconversion of inactive and active glucocorticoids. Impaired regulation of these enzymes has been associated with obesity, diabetes, hypertension, and cardiovascular disease. Previous studies in animals and humans suggested that dehydroepiandrosterone (DHEA) has antiglucocorticoid effects, but the underlying mechanisms are unknown. In this study, DHEA treatment markedly increased mRNA expression and activity of 11beta-HSD2 in a rat cortical collecting duct cell line and in kidneys of C57BL/6J mice and Sprague-Dawley rats. DHEA-treated rats tended to have reduced urinary corticosterone to 11-dehydrocorticosterone ratios. It was found that CCAAT/enhancer-binding protein-alpha (C/EBP-alpha) and C/EBP-beta regulated HSD11B2 transcription and that DHEA likely modulated the transcription of 11beta-HSD2 in a phosphatidylinositol-3 kinase/Akt-dependent manner by increasing C/EBP-beta mRNA and protein expression. Moreover, it is shown that C/EBP-alpha and C/EBP-beta differentially regulate the expression of 11beta-HSD1 and 11beta-HSD2. In conclusion, DHEA induces a shift from 11beta-HSD1 to 11beta-HSD2 expression, increasing conversion from active to inactive glucocorticoids. This provides a possible explanation for the antiglucocorticoid effects of DHEA.

Ceramide and adenosine 5'-monophosphate-activated protein kinase are two novel regulators of 11beta-hydroxysteroid dehydrogenase type 1 expression and activity in cultured preadipocytes

Increased activity of intracellular glucocorticoid reactivating enzyme, 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) in obese adipose tissue contributes to adipose dysfunction. As recent studies have highlighted a potential role of preadipocytes in adipose dysfunction, we tested the hypothesis that a variety of metabolic stress mediated by ceramide or AMP-activated protein kinase (AMPK) would regulate 11beta-HSD1 in preadipocytes. The present study is the first to show that 1) expression of 11beta-HSD1 in 3T3-L1 preadipocytes was robustly induced when cells were treated with cell-permeable ceramide analogue C(2) ceramide, bacterial sphingomyelinase, and sphingosine 1-phosphate, 2) 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR)-induced activation of AMPK augmented the expression and enzyme activity of 11beta-HSD1, and 3) these results were reproduced in human preadipocytes. We demonstrate for the first time that C(2) ceramide and AICAR markedly induced the expression of CCAAT/enhancer-binding protein (C/EBP) beta and its binding to 11beta-HSD1 promoter. Transient knockdown of C/EBPbeta protein by small interfering RNA markedly attenuated the expression of 11beta-HSD1 induced by C(2) ceramide or AICAR. The present study provides novel evidence that ceramide- and AMPK-mediated signaling pathways augment the expression and activity of 11beta-HSD1 in preadipocytes by way of C/EBPbeta, thereby highlighting a novel, metabolic stress-related regulation of 11beta-HSD1 in a cell-specific manner.

Cell-type specific regulation of the human 11beta-hydroxysteroid dehydrogenase type 1 promoter

The intracellular enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) converts cortisone into the more active metabolite cortisol. Overexpression of 11beta-HSD1 was associated with features of the metabolic syndrome such as obesity or impaired glucose tolerance. Despite this considerable impact of 11beta-HSD1, the human 11beta-HSD1 promoter has not been described in detail yet. We therefore cloned eight different promoter fragments of the 5'-upstream region of the known transcription/translation-start up to -3034 bp into the luciferase-reporter vector pGL3. A low-cost in-house assay was developed and validated to detect firefly and renilla luciferase activity. Promoter fragments were analysed in human HepG2 and undifferentiated and differentiated murine 3T3-L1 cells. A differential regulation of the human 11beta-HSD1 promoter depending upon the cell type was observed. Specifically, a strong repressor of the basal promoter activity was found between -85 and -172 bp in HepG2 cells only, while an additional repressor appeared to be active between -342 and -823 bp in both, the hepatic and the adipose cell line. The presented data suggest a cell-type specific regulation of the 11beta-HSD1 promoter, which is in agreement with existing expression data from animal and human studies. The described promoter constructs will allow subsequent studies about the role of specific hormonal, metabolic and transcription factors to finally characterise the regulation of the human 11beta-HSD1-promoter in more detail.