The p38 mitogen-activated protein kinase regulates 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) expression in human trophoblast cells through modulation of 11beta-HSD2 messenger ribonucleic acid stability

11β-Hydroxysteroid dehydrogenase type 2 may mediate the stress-specific effects of cortisol on brain cell proliferation in adult zebrafish (Danio rerio)

Stress-induced increases in cortisol can stimulate or inhibit brain cell proliferation, but the mechanisms behind these opposing effects are unknown. We tested the hypothesis that 11β-hydroxysteroid dehydrogenase type 2 (Hsd11b2), a glucocorticoid-inactivating enzyme expressed in neurogenic regions of the adult zebrafish brain, mitigates cortisol-induced changes to brain cell proliferation, using one of three stress regimes: a single 1 min air exposure (acute stress), two air exposures spaced 24 h apart (repeat acute stress) or social subordination (chronic stress). Plasma cortisol was significantly elevated 15 min after air exposure and recovered within 24 h after acute and repeat acute stress, whereas subordinate fish exhibited significant and sustained elevations relative to dominant fish for 24 h. Following acute stress, brain hsd11b2 transcript abundance was elevated up to 6 h after a single air exposure but was unchanged by repeat acute stress or social subordination. A sustained increase in brain Hsd11b2 protein levels occurred after acute stress, but not after repeat or chronic stress. Following acute and repeat acute stress, brain pcna transcript abundance (a marker of cell proliferation) exhibited a prolonged elevation, but was unaffected by social subordination. Interestingly, the number of telencephalic BrdU+ cells increased in fish after a single air exposure but was unchanged by repeat acute stress. Following acute and repeat acute stress, fish expressed lower brain glucocorticoid and mineralocorticoid receptor (gr and mr) transcript abundance while subordinate fish exhibited no changes. Taken together, these results demonstrate stressor-specific regulation of Hsd11b2 in the zebrafish brain that could modulate rates of cortisol catabolism contributing to observed differences in brain cell proliferation.

Does the Caesarean Section Impact on 11β HSD2 and Fetal Cortisol?

Purpose: Comparison of the activity of 11beta-hydroxysteroid dehydrogenase type 2 in the placenta and the umbilical cord blood cortisol level between caesarean sections with or without uterine contraction and vaginal delivery groups. Cortisol is the main stress hormone responsible for the normal adaptation of the neonate to extrauterine life. The disorders resulting from a dysfunction of the 11β-HSD 2–cortisol system can explain the higher risk of developing diseases in children born by caesarean section. Methods: 111 healthy, pregnant women in singular pregnancy at term of delivery were included into the study. The study comprised 11β-HSD 2 in placental tissue from 49 pregnant women delivering by elective caesarean section and 46 pregnant women delivering by vagina. In 16 cases of the elective caesarean section, regular uterine contractions were declared. Cortisol level was estimated in umbilical cord blood directly after delivery. Results: We found no statistically significant differences in the activity of 11β-HSD 2 in placentas delivered via caesarean sections (29.61 on average in elective caesarean sections and 26.65 on average in intrapartum caesarean sections) compared to vaginal deliveries (31.94 on average, p = 0.381), while umbilical cord blood cortisol in the elective caesarean sections group was significantly lower (29.86 on average) compared to the vaginal deliveries (55.50 on average, p < 0.001) and intrapartum caesarean sections (52.27 on average, p < 0.001). Conclusions: The model of placental 11β-HSD 2 activity and umbilical cord blood cortisol concentration seems to be significant in conditions of stress associated with natural uterine contractions in labour.

Tributyltin and triphenyltin induce 11β-hydroxysteroid dehydrogenase 2 expression and activity through activation of retinoid X receptor α

Exposure to the environmental pollutants organotins is of toxicological concern for the marine ecosystem and sensitive human populations, including pregnant women and their unborn children. Using a placenta cell model, we investigated whether organotins at nanomolar concentrations affect the expression and activity of 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2). 11β-HSD2 represents a placental barrier controlling access of maternal glucocorticoids to the fetus. The organotins tributyltin (TBT) and triphenyltin (TPT) induced 11β-HSD2 expression and activity in JEG-3 placenta cells, an effect confirmed at the mRNA level in primary human trophoblast cells. Inhibition/knock-down of retinoid X receptor alpha (RXRα) in JEG-3 cells reduced the effect of organotins on 11β-HSD2 activity, mRNA and protein levels, revealing involvement of RXRα. Experiments using RNA and protein synthesis inhibitors indicated that the effect of organotins on 11β-HSD2 expression was direct and caused by increased transcription. Induction of placental 11β-HSD2 activity by TBT, TPT and other endocrine disrupting chemicals acting as RXRα agonists may affect placental barrier function by altering the expression of glucocorticoid-dependent genes and resulting in decreased availability of active glucocorticoids for the fetus, disturbing development and increasing the risk for metabolic and cardiovascular complications in later life.

Mechanisms for establishment of the placental glucocorticoid barrier, a guard for life

The fetus is shielded from the adverse effects of excessive maternal glucocorticoids by 11β-HSD2, an enzyme which is expressed in the syncytial layer of the placental villi and is capable of converting biologically active cortisol into inactive cortisone. Impairment of this placental glucocorticoid barrier is associated with fetal intrauterine growth restriction (IUGR) and development of chronic diseases in later life. Ontogeny studies show that the expression of 11β-HSD2 is initiated at a very early stage after conception and increases with gestational age but declines around term. The promoter for HSD11B2, the gene encoding 11β-HSD2, has a highly GC-rich core. However, the pattern of methylation on HSD11B2 may have already been set up in the blastocyst when the trophoblast identity is committed. Instead, hCG-initiated signals appear to be responsible for the upsurge of 11β-HSD2 expression during trophoblast syncytialization. By activating the cAMP/PKA pathway, hCG not only alters the modification of histones but also increases the expression of Sp1 which activates the transcription of HSD11B2. Adverse conditions such as stress, hypoxia and nutritional restriction can cause IUGR of the fetus. It appears that different causes of IUGR may attenuate HSD11B2 expression differentially in the placenta. While stress and nutritional restriction may reduce HSD11B2 expression by increasing its methylation, hypoxia may decrease HSD11B2 expression via alternative mechanisms rather than by methylation. Herein, we summarize the advances in the study of mechanisms underlying the establishment of the placental glucocorticoid barrier and the attenuation of this barrier by adverse conditions during pregnancy.

Oxidative stress-induced TGF-beta/TAB1-mediated p38MAPK activation in human amnion epithelial cells

Term and preterm parturition are associated with oxidative stress (OS)-induced p38 mitogen-activated protein kinase (p38MAPK)-mediated fetal tissue (amniochorion) senescence. p38MAPK activation is a complex cell- and stimulant-dependent process. Two independent pathways of OS-induced p38MAPK activation were investigated in amnion epithelial cells (AECs) in response to cigarette smoke extract (CSE: a validated OS inducer in fetal cells): (1) the OS-mediated oxidation of apoptosis signal-regulating kinase (ASK)-1 bound Thioredoxin (Trx[SH]2) dissociates this complex, creating free and activated ASK1-signalosome and (2) transforming growth factor-mediated activation of (TGF)-beta-activated kinase (TAK)1 and TGF-beta-activated kinase 1-binding protein (TAB)1. AECs isolated from normal term, not-in-labor fetal membranes increased p38MAPK in response to CSE and downregulated it in response to antioxidant N-acetylcysteine. In AECs, both Trx and ASK1 were localized; however, they remained dissociated and not complexed, regardless of conditions. Silencing either ASK1 or its downstream effectors (MKK3/6) did not affect OS-induced p38MAPK activation. Conversely, OS increased TGF-beta's release from AECs and increased phosphorylation of both p38MAPK and TAB1. Silencing of TAB1, but not TAK1, prevented p38MAPK activation, which is indicative of TAB1-mediated autophosphorylation of p38MAPK, an activation mechanism seldom seen. OS-induced p38MAPK activation in AECs is ASK1-Trx signalosome-independent and is mediated by the TGF-beta pathway. This knowledge will help to design strategies to reduce p38MAPK activation-associated pregnancy risks.

Placental Origins of Chronic Disease

Epidemiological evidence links an individual's susceptibility to chronic disease in adult life to events during their intrauterine phase of development. Biologically this should not be unexpected, for organ systems are at their most plastic when progenitor cells are proliferating and differentiating. Influences operating at this time can permanently affect their structure and functional capacity, and the activity of enzyme systems and endocrine axes. It is now appreciated that such effects lay the foundations for a diverse array of diseases that become manifest many years later, often in response to secondary environmental stressors. Fetal development is underpinned by the placenta, the organ that forms the interface between the fetus and its mother. All nutrients and oxygen reaching the fetus must pass through this organ. The placenta also has major endocrine functions, orchestrating maternal adaptations to pregnancy and mobilizing resources for fetal use. In addition, it acts as a selective barrier, creating a protective milieu by minimizing exposure of the fetus to maternal hormones, such as glucocorticoids, xenobiotics, pathogens, and parasites. The placenta shows a remarkable capacity to adapt to adverse environmental cues and lessen their impact on the fetus. However, if placental function is impaired, or its capacity to adapt is exceeded, then fetal development may be compromised. Here, we explore the complex relationships between the placental phenotype and developmental programming of chronic disease in the offspring. Ensuring optimal placentation offers a new approach to the prevention of disorders such as cardiovascular disease, diabetes, and obesity, which are reaching epidemic proportions.

Class-Specific Histone Deacetylase Inhibitors Promote 11-Beta Hydroxysteroid Dehydrogenase Type 2 Expression in JEG-3 Cells

Exposure to maternal cortisol plays a crucial role in fetal organogenesis. However, fetal overexposure to cortisol has been linked to a range of short- and long-term adverse outcomes. Normally, this is prevented by the expression of an enzyme in the placenta called 11-beta hydroxysteroid dehydrogenase type 2 (11β-HSD2) which converts active cortisol to its inactive metabolite cortisone. Placental 11β-HSD2 is known to be reduced in a number of adverse pregnancy complications, possibly through an epigenetic mechanism. As a result, a number of pan-HDAC inhibitors have been examined for their ability to promote 11β-HSD2 expression. However, it is not known if the effects of pan-HDAC inhibition are a general phenomenon or if the effects are dependent upon a specific class of HDACs. Here, we examined the ability of pan- and class-specific HDAC inhibitors to regulate 11β-HSD2 expression in JEG3 cells. We find that pan-, class I, or class IIa HDAC inhibition promoted 11β-HSD2 expression and prevented cortisol or interleukin-1β-induced decrease in its expression. These results demonstrate that targeting a specific class of HDACs can promote 11β-HSD2 expression in JEG3 cells. This adds to the growing body of evidence suggesting that HDACs may be crucial in maintaining normal fetal development.

Nutritional marginal zinc deficiency disrupts placental 11β-hydroxysteroid dehydrogenase type 2 modulation

This paper investigated if marginal zinc nutrition during gestation could affect fetal exposure to glucocorticoids as a consequence of a deregulation of placental 11βHSD2 expression. Placenta 11β-hydroxysteroid dehydrogenase type 2 (11βHSD2) plays a central role as a barrier protecting the fetus from the deleterious effects of excess maternal glucocorticoids. Rats were fed control (25 μg zinc per g diet) or marginal (10 μg zinc per g diet, MZD) zinc diets from day 0 through day 19 (GD19) of gestation. At GD19, corticosterone concentration in plasma, placenta, and amniotic fluid was similar in both groups. However, protein and mRNA levels of placenta 11βHSD2 were significantly higher (25% and 58%, respectively) in MZD dams than in controls. The main signaling cascades modulating 11βHSD2 expression were assessed. In MZD placentas the activation of ERK1/2 and of the downstream transcription factor Egr-1 was low, while p38 phosphorylation and SP-1-DNA binding were low compared to the controls. These results point to a central role of ERK1/Egr-1 in the regulation of 11βHSD2 expression under the conditions of limited zinc availability. In summary, results show that an increase in placenta 11βHSD2 expression occurs as a consequence of gestational marginal zinc nutrition. This seems to be due to a low tissue zinc-associated deregulation of ERK1/2 rather than to exposure to high maternal glucocorticoid exposure. The deleterious effects on brain development caused by diet-induced marginal zinc deficiency in rats do not seem to be due to fetal exposure to excess glucocorticoids.

11β-Hydroxysteroid Dehydrogenase 2 in Preeclampsia

Preeclampsia is a serious medical problem affecting the mother and her child and influences their health not only during the pregnancy, but also many years after. Although preeclampsia is a subject of many research projects, the etiology of the condition remains unclear. One of the hypotheses related to the etiology of preeclampsia is the deficiency in placental 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2), the enzyme which in normal pregnancy protects the fetus from the excess of maternal cortisol. The reduced activity of the enzyme was observed in placentas from pregnancies complicated with preeclampsia. That suggests the overexposure of the developing child to maternal cortisol, which in high levels exerts proapoptotic effects and reduces fetal growth. The fetal growth restriction due to the diminished placental 11β-HSD2 function may be supported by the fact that preeclampsia is often accompanied with fetal hypotrophy. The causes of the reduced function of 11β-HSD2 in placental tissue are still discussed. This paper summarizes the phenomena that may affect the activity of the enzyme at various steps on the way from the gene to the protein.

Bisphenol A disrupts gene expression in human placental trophoblast cells

This study examined the effect of bisphenol A (BPA) on human placental gene expression using primary trophoblast cells as an in vitro model system. Trophoblast cells were isolated from human placentas at term, cultured and then exposed to environmentally relevant concentrations of BPA (0.1-2 μg/ml) for up to 24h, after which levels of 11β-HSD2 mRNA, protein and activity were determined by standard radiometric conversion assay, western blotting, and qRT-PCR, respectively. The mRNA levels of several other prominent placental hormones/factors were also assessed by qRT-PCR. BPA dramatically increased levels of 11β-HSD2 activity, protein and mRNA in a time- and concentration-dependent manner (> 4-fold). BPA also augmented aromatase, glucose transporter-1, CRH, and hCG mRNA levels while reducing the level of leptin mRNA. These findings demonstrate that BPA severely disrupts human placental gene expression in vitro, which suggests that exposure to BPA may contribute to altered placental function and consequent pregnancy complications.

Analysis of gene expression and preliminary study of methylation about 11β-HSD2 gene in placentas of Chinese pre-eclampsia patients of Han ethnicity

AIMS

The aim of this study was to determine the promoter methylation status of type 2 isoform of 11β-hydroxysteroid dehydrogenase (11β-HSD2) and its regulatory correlation with 11β-HSD2 gene expression in placentas of pre-eclampsia (PE) patients of Chinese Han ethnicity.

MATERIAL AND METHODS

The pathological features of placental tissues were studied using hematoxylin-eosin staining and immunohistochemical staining. The 11β-HSD2 mRNA and protein expressions were detected by real-time polymerase chain reaction and Western blotting. The methylation of the 11β-HSD2 promoter sequence was examined by bisulfite sequencing polymerase chain reaction.

RESULTS

Trophoblast hyperplasia and discontinuous syncytial layer were observed in the PE group, and the 11β-HSD2 was distributed irregularly and its immunoreactivity was weakened distinctly. The expressions of 11β-HSD2 mRNA and protein decreased significantly in the PE group compared with the control group. Unexpectedly, almost no 11β-HSD2 methylation was detected in PE placental tissue (two fragments, 0.6% vs 0%) or normal placental tissue (1% vs 0.6%). No significant difference in 11β-HSD2 promoter methylation was found between the two groups.

CONCLUSIONS

The 11β-HSD2 expression decreased in PE women of Chinese Han ethnicity, but was not interrelated with the promoter methylation status.

Cross-talk between cAMP and MAPK pathways in HSD11B2 induction by hCG in placental trophoblasts

Overexposure of the fetus to glucocorticoids in gestation is detrimental to fetal development. The passage of maternal glucocorticoids into the fetal circulation is governed by 11beta-Hydroxysteroid Dehydrogenase Type 2 (HSD11B2) in the placental syncytiotrophoblasts. Human chorionic gonadotropin (hCG) plays an important role in maintaining placental HSD11B2 expression via activation of the cAMP pathway. In this study, we investigated the relationship between the activation of the cAMP pathway by hCG and subsequent phosphorylation of extracellular signal-regulated kinase1/2 (ERK1/2) or p38 mitogen-activated protein kinase (MAPK) pathways in the regulation of placental HSD11B2 expression in human placental syncytiotrophoblasts. We found that treatment of the placental syncytiotrophoblasts with either hCG or dibutyl cAMP (dbcAMP) could promote the phosphorylation of p38 and ERK1/2. Inhibition of p38 MAPK with SB203580 not only reduced the basal HSD11B2 mRNA and protein levels but also attenuated HSD11B2 levels induced by either hCG or dbcAMP. By contrast, inhibition of ERK1/2 with PD98059 increased the basal mRNA and protein levels of HSD11B2 and had no effect on HSD11B2 mRNA and protein levels induced by either hCG or dbcAMP. These data suggest that p38 MAPK is involved in both basal and hCG/cAMP-induced expression of HSD11B2, and ERK1/2 may play a role opposite to p38 MAPK at least in the basal expression of HSD11B2 in human placental syncytiotrophoblasts and that there is complicated cross-talk between hCG/cAMP and MAPK cascades in the regulation of placental HSD11B2 expression.

Variants of 11β-hydroxysteroid dehydrogenase (HSD11B) gene type 1 and 2 in Chinese obese adolescents

OBJECTIVE

To investigate the relationship between 11β-hydroxysteroid dehydrogenase (HSD11B) gene type 1 and 2 and obesity in Chinese children.

METHODS

A total of 400 obese and 200 healthy adolescents were enrolled as obese and control groups. Seven SNPs in HSD11B1 (rs4393158, rs2235543, rs10082248, rs10863782, rs2236903, rs2298930, rs4545339) and four variants in HSD11B2 gene (rs28934592, rs28934591, rs28934594 and rs28934593) were measured by automated platform MassArray.

RESULTS

The rs28934592 in HSD11B2 and rs10863782 in HSD11B1 were excluded as false positive or HWE P < 0.05. Moreover, one allele type was found in the other three locations of HSD11B2. The minor allele frequency of rs2235543 and rs10082248 was higher in patients than that in controls (P = 0.045, P = 0.041, respectively). The rs10082248, rs2298930 and rs4545339 were associated with the risk of obesity in the recessive model (P < 0.05, respectively). Moreover, the total cholesterol in patients with GG or AG genotype was significantly higher than that in patients with AA genotype in rs10082248. The rs4393158 was associated with the hypertension in log-additive model test (P = 0.037), and glucose abnormal and hypercholesteremia in dominant model test (P < 0.05, respectively), while the rs2235543 was associated with hypercholesteremia in overdominant model test (P = 0.017).

CONCLUSIONS

The polymorphism of HSD11B1 may be a cause of childhood obesity, or even associated with the complication of childhood obesity. However, variants of HSD11B2 may be not a cause of obesity.

Activation of endocrine-related gene expression in placental choriocarcinoma cell lines following DNA methylation knock-down

Increasingly, placental DNA methylation is assessed as a factor in pregnancy-related complications, yet the transcriptional impact of such findings is not always clear. Using a proliferative in vitro placental model, the effect of DNA methylation loss on gene activation was evaluated at a number of genes selected for being differentially methylated in pre-eclampsia-associated placentae in vivo. We aimed to determine whether reduced DNA methylation at specific loci was associated with transcriptional changes at the corresponding gene, thus providing mechanistic underpinnings for previous clinical findings and to assess the degree of transcriptional response amongst our candidate genes. BeWo and JEG3 choriocarcinoma cells were exposed to 1 μM 5-Aza-2'-deoxycytidine (5-Aza-CdR) or vehicle control for 48 h, and re-plated and cultured for a further 72 h in normal media before cells were harvested for RNA and DNA. Bisulphite pyrosequencing confirmed that DNA methylation was reduced by ∼30-50% points at the selected loci studied in both cell lines. Gene activation, measured by qRT-PCR, was highly variable and transcript specific, indicating differential sensitivity to DNA methylation. Most notably, loss of DNA methylation at the leptin (LEP) promoter corresponded to a 200-fold and 40-fold increase in LEP expression in BeWo and JEG3 cells, respectively (P < 0.01). Transcripts of steroidogenic pathway enzymes CYP11A1 and HSD3B1 were up-regulated ∼40-fold in response to 5-Aza-CdR exposure in BeWo cells (P < 0.01). Other transcripts, including aromatase (CYP19), HSD11B2, inhibin (INHBA) and glucocorticoid receptor (NR3C1) were more moderately, although significantly, affected by loss of associated DNA methylation. These data present a mixed effect of DNA methylation changes at selected loci supporting cautionary interpretation of DNA methylation results in the absence of functional data.

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.

Metallothionein-I- and -II-deficient mice display increased susceptibility to cadmium-induced fetal growth restriction

Maternal cadmium exposure induces fetal growth restriction (FGR), but the underlying mechanisms remain largely unknown. The placenta is the main organ known to protect the fetus from environmental toxins such as cadmium. In this study, we examine the role of the two key placental factors in cadmium-induced FGR. The first is placental enzyme 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2), which is known to protect the fetus from exposure to high cortisol levels and subsequently FGR, and the second the cadmium binding/sequestering proteins metallotheionein (MT)-I and -II. Using the MT-I/II(-/-) mouse model, pregnant mice were administered cadmium, following which pups and placentas were collected and examined. MT-I/II(-/-) pups exposed to cadmium were significantly growth restricted, but neither placental weight nor 11β-HSD2 was altered. Although cadmium administration did not result in any visible structural changes in the placenta, increased apoptosis was detected in MT-I/II(-/-) placentas following cadmium exposure, with a significant increase in levels of both p53 and caspase 3 proteins. Additionally, glucose transporter (GLUT1) was significantly reduced in MT-I/II(-/-) placentas of pups exposed to cadmium, whereas zinc transporter (ZnT-1) remained unaltered. Taken together, these results demonstrate that MT-I/II(-/-) mice are more vulnerable to cadmium-induced FGR. The present data also suggest that increased apoptosis and reduced GLUT1 expression in the placenta contribute to the molecular mechanisms underlying cadmium-induced FGR.

Down-regulation of 11β-hydroxysteroid dehydrogenase type 2 by bortezomib sensitizes Jurkat leukemia T cells against glucocorticoid-induced apoptosis

11β-hydroxysteroid dehydrogenases type 2 (11β-HSD2), a key regulator for pre-receptor metabolism of glucocorticoids (GCs) by converting active GC, cortisol, to inactive cortisone, has been shown to be present in a variety of tumors. But its expression and roles have rarely been discussed in hematological malignancies. Proteasome inhibitor bortezomib has been shown to not only possess antitumor effects but also potentiate the activity of other chemotherapeutics. In this study, we demonstrated that 11β-HSD2 was highly expressed in two GC-resistant T-cell leukemic cell lines Jurkat and Molt4. In contrast, no 11β-HSD2 expression was found in two GC-sensitive non-hodgkin lymphoma cell lines Daudi and Raji as well as normal peripheral blood T cells. Inhibition of 11β-HSD2 by 11β-HSD inhibitor 18β-glycyrrhetinic acid or 11β-HSD2 shRNA significantly increased cortisol-induced apoptosis in Jurkat cells. Additionally, pretreatment of Jurkat cells with low-dose bortezomib resulted in increased cellular sensitivity to GC as shown by elevated induction of apoptosis, more cells arrested at G1 stage and up-regulation of GC-induced leucine zipper which is an important mediator of GC action. Furthermore, we clarified that bortezomib could dose-dependently inhibit 11β-HSD2 messenger RNA and protein levels as well as activity (cortisol-cortisone conversion) through p38 mitogen-activated protein kinase signaling pathway. Therefore, we suggest 11β-HSD2 is, at least partially if not all, responsible for impaired GC suppression in Jurkat cells and also indicate a novel mechanism by which proteasome inhibitor bortezomib may influence GC action.

Fetal programming by maternal stress: Insights from a conflict perspective

Maternal stress during pregnancy has pervasive effects on the offspring's physiology and behavior, including the development of anxious, reactive temperament and increased stress responsivity. These outcomes can be seen as the result of adaptive developmental plasticity: maternal stress hormones carry useful information about the state of the external world, which can be used by the developing fetus to match its phenotype to the predicted environment. This account, however, neglects the inherent conflict of interest between mother and fetus about the outcomes of fetal programming. The aim of this paper is to extend the adaptive model of prenatal stress by framing mother-fetus interactions in an evolutionary conflict perspective. In the paper, I show how a conflict perspective provides many new insights in the functions and mechanisms of fetal programming, with particular emphasis on human pregnancy. I then take advantage of those insights to make sense of some puzzling features of maternal and fetal physiology and generate novel empirical predictions.

Corticotropin-releasing hormone stimulates expression of leptin, 11beta-HSD2 and syncytin-1 in primary human trophoblasts

BACKGROUND

The placental syncytiotrophoblast is the major source of maternal plasma corticotropin-releasing hormone (CRH) in the second half of pregnancy. Placental CRH exerts multiple functions in the maternal organism: It induces the adrenal secretion of cortisol via the stimulation of adrenocorticotropic hormone, regulates the timing of birth via its actions in the myometrium and inhibits the invasion of extravillous trophoblast cells in vitro. However, the auto- and paracrine actions of CRH on the syncytiotrophoblast itself are unknown. Intrauterine growth restriction (IUGR) is accompanied by an increase in placental CRH, which could be of pathophysiological relevance for the dysregulation in syncytialisation seen in IUGR placentas.

METHODS

We aimed to determine the effect of CRH on isolated primary trophoblastic cells in vitro. After CRH stimulation the trophoblast syncytialisation rate was monitored via syncytin-1 gene expression and beta-hCG (beta-human chorionic gonadotropine) ELISA in culture supernatant. The expression of the IUGR marker genes leptin and 11beta-hydroxysteroid dehydrogenase 2 (11beta-HSD2) was measured continuously over a period of 72 h. We hypothesized that CRH might attenuate syncytialisation, induce leptin, and reduce 11beta-HSD2 expression in primary villous trophoblasts, which are known features of IUGR.

RESULTS

CRH did not influence the differentiation of isolated trophoblasts into functional syncytium as determined by beta-hCG secretion, albeit inducing syncytin-1 expression. Following syncytialisation, CRH treatment significantly increased leptin and 11beta-HSD2 expression, as well as leptin secretion into culture supernatant after 48 h.

CONCLUSION

The relevance of CRH for placental physiology is underlined by the present in vitro study. The induction of leptin and 11beta-HSD2 in the syncytiotrophoblast by CRH might promote fetal nutrient supply and placental corticosteroid metabolism in the phase before labour induction.

Gene targeting in primary human trophoblasts

Studies in primary human trophoblasts provide critical insights into placental function in normal and complicated pregnancies. Mechanistic studies in these cells require experimental tools to modulate gene expression. Lipid-based methods to transfect primary trophoblasts are fairly simple to use and allow for the efficient delivery of nucleic acids, but potential toxic effects limit these methods. Viral vectors are versatile transfection tools of native trophoblastic or foreign cDNAs, providing high transfection efficiency, low toxicity and stable DNA integration into the trophoblast genome. RNA interference (RNAi), using small interfering RNA (siRNA) or microRNA, constitutes a powerful approach to silence trophoblast genes. However, off-target effects, such as regulation of unintended complementary transcripts, inflammatory responses and saturation of the endogenous RNAi machinery, are significant concerns. Strategies to minimize off-target effects include using multiple individual siRNAs, elimination of pro-inflammatory sequences in the siRNA construct and chemical modification of a nucleotide in the guide strand or of the ribose moiety. Tools for efficient gene targeting in primary human trophoblasts are currently available, albeit not yet extensively validated. These methods are critical for exploring the function of human trophoblast genes and may provide a foundation for the future application of gene therapy that targets placental trophoblasts.

Caffeine reduces 11β-hydroxysteroid dehydrogenase type 2 expression in human trophoblast cells through the adenosine A(2B) receptor

Maternal caffeine consumption is associated with reduced fetal growth, but the underlying molecular mechanisms are unknown. Since there is evidence that decreased placental 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) is linked to fetal growth restriction, we hypothesized that caffeine may inhibit fetal growth partly through down regulating placental 11β-HSD2. As a first step in examining this hypothesis, we studied the effects of caffeine on placental 11β-HSD2 activity and expression using our established primary human trophoblast cells as an in vitro model system. Given that maternal serum concentrations of paraxanthine (the primary metabolite of caffeine) were greater in women who gave birth to small-for-gestational age infants than to appropriately grown infants, we also studied the effects of paraxanthine. Our main findings were: (1) both caffeine and paraxanthine decreased placental 11β-HSD2 activity, protein and mRNA in a concentration-dependent manner; (2) this inhibitory effect was mediated by the adenosine A(2B) receptor, since siRNA-mediated knockdown of this receptor prevented caffeine- and paraxanthine-induced inhibition of placental 11β-HSD2; and (3) forskolin (an activator of adenyl cyclase and a known stimulator of 11β-HSD2) abrogated the inhibitory effects of both caffeine and paraxanthine, which provides evidence for a functional link between exposure to caffeine and paraxanthine, decreased intracellular levels of cAMP and reduced placental 11β-HSD2. Taken together, these findings reveal that placental 11β-HSD2 is a novel molecular target through which caffeine may adversely affect fetal growth. They also uncover a previously unappreciated role for the adenosine A(2B) receptor signaling in regulating placental 11β-HSD2, and consequently fetal development.

11β-hydroxysteroid dehydrogenases and the brain: from zero to hero, a decade of progress

Glucocorticoids have profound effects on brain development and adult CNS function. Excess or insufficient glucocorticoids cause myriad abnormalities from development to ageing. The actions of glucocorticoids within cells are determined not only by blood steroid levels and target cell receptor density, but also by intracellular metabolism by 11β-hydroxysteroid dehydrogenases (11β-HSD). 11β-HSD1 regenerates active glucocorticoids from their inactive 11-keto derivatives and is widely expressed throughout the adult CNS. Elevated hippocampal and neocortical 11β-HSD1 is observed with ageing and causes cognitive decline; its deficiency prevents the emergence of cognitive defects with age. Conversely, 11β-HSD2 is a dehydrogenase, inactivating glucocorticoids. The major central effects of 11β-HSD2 occur in development, as expression of 11β-HSD2 is high in fetal brain and placenta. Deficient feto-placental 11β-HSD2 results in a life-long phenotype of anxiety and cardiometabolic disorders, consistent with early life glucocorticoid programming.

Keratinocyte growth factor promotes preadipocyte proliferation via an autocrine mechanism

Keratinocyte growth factor (KGF; also known as FGF-7) is a well-characterized paracrine growth factor for tissue growth and regeneration. However, its role in adipose tissue, which is known to undergo tremendous expansion in obesity, is virtually unknown. Given that we previously identified KGF as one of the up-regulated growth factors in adipose tissue of an early-life programmed rat model of visceral obesity, the present study was undertaken to examine the hypothesis that KGF promotes adipogenesis. Using 3T3-L1 and rat primary preadipocytes as in vitro model systems, we demonstrated that (1) KGF stimulated preadipocyte proliferation in a concentration-dependent manner with a maximal effect at 2.5 ng/ml (approximately 2-fold increase); (2) KGF mRNA was highly expressed in rat adipocytes and preadipocytes as well as 3T3-L1 cells; (3) treatment of preadipocytes with a neutralizing antibody against KGF and siRNA-mediated knockdown of KGF led to a 50% reduction in their proliferative capacity; (4) KGF activated the protein kinase Akt, and the PI3 kinase inhibitor LY294002 blocked KGF stimulation of preadipocyte proliferation; and (5) KGF did not promote differentiation of preadipocytes to mature adipocytes. Together, these results reveal adipocytes and their precursor cells as novel sites of KGF production. Importantly, they also demonstrate that KGF promotes preadipocyte proliferation by an autocrine mechanism that involves activation of the PI3K/Akt signaling pathway. Aberrant KGF expression may have consequences not only for normal adipose tissue growth but also for the pathogenesis of obesity.

BMP-3 promotes mesenchymal stem cell proliferation through the TGF-beta/activin signaling pathway

Adipogenesis plays a key role in the pathogenesis of obesity. It begins with the commitment of mesenchymal stem cells (MSCs) to the adipocyte lineage, followed by terminal differentiation of preadipocytes to mature adipocytes. A critical, but poorly understood, component of adipogenesis involves proliferation of MSCs and preadipocytes. The present study was undertaken to examine the hypothesis that bone morphogenetic protein-3 (BMP-3) promotes adipogenesis using C3H10T1/2 MSCs and 3T3-L1 preadipocytes as in vitro model systems. We demonstrated that although it did not promote the commitment of MSCs to the adipocyte lineage or the differentiation of preadipocytes to adipocytes, BMP-3-stimulated proliferation by threefold in both cell types. Owing to a lack of information on MSC proliferation, we then delineated the molecular mechanisms underlying BMP-3-stimulated MSC proliferation. We showed that BMP-3 activated the transforming growth factor-beta (TGF-beta)/activin but not ERK1/2, p38 MAPK, or JNK signaling pathways in C3H10T1/2 cells. Furthermore, the TGF-beta/activin receptor kinase inhibitor SB-431542 blocked BMP-3-stimulated proliferation. Importantly, siRNA-mediated knockdown of the key TGF-beta/activin signaling pathway components, ActRIIB, ALK4, or Smad2, abrogated the mitogenic effects of BMP-3 on MSCs. Together, these results demonstrate that BMP-3 stimulates MSC proliferation via the TGF-beta/activin signaling pathway, thus revealing a novel role for this divergent and poorly understood member of the TGF-beta superfamily in regulating MSC proliferation.