Molecular mechanism of suppression of testicular steroidogenesis by proinflammatory cytokine tumor necrosis factor alpha

Hairless and NFκB form a positive feedback loop after UVB and TNFα stimulation

Hairless (HR) is a nuclear protein with corepressor activity whose exact function in the skin remains to be determined. Mutations in both human and mouse Hairless lead to hair loss accompanied by the appearance of papules, a disorder called atrichia with papular lesions. Furthermore, mice with mutations in HR are known to have a higher susceptibility to ultraviolet radiation-induced tumorigenesis, suggesting that HR plays a crucial role in the epidermal UVB response. Using normal human keratinocytes (NHKs) and keratinocytes containing a mutation in HR, we found that HR is an early UVB response gene that negatively regulates NFκB mRNA expression. HR mutant keratinocytes have a dysregulated UVB response that includes increased proliferation and the aberrant activation of NFκB effector genes. Additionally, we show that another UVB response gene, TNFα, negatively regulates HR mRNA expression. TNFα-induced negative regulation of HR occurs through a direct interaction of the p65 subunit with a single NFκB-binding domain located in the HR promoter region. Therefore, we show for the first time that HR and NFκB participate in a positive feedback loop that can be initiated either by UVB or TNFα.

The blood-testis barrier and its implications for male contraception

The blood-testis barrier (BTB) is one of the tightest blood-tissue barriers in the mammalian body. It divides the seminiferous epithelium into the basal and the apical (adluminal) compartments. Meiosis I and II, spermiogenesis, and spermiation all take place in a specialized microenvironment behind the BTB in the apical compartment, but spermatogonial renewal and differentiation and cell cycle progression up to the preleptotene spermatocyte stage take place outside of the BTB in the basal compartment of the epithelium. However, the BTB is not a static ultrastructure. Instead, it undergoes extensive restructuring during the seminiferous epithelial cycle of spermatogenesis at stage VIII to allow the transit of preleptotene spermatocytes at the BTB. Yet the immunological barrier conferred by the BTB cannot be compromised, even transiently, during the epithelial cycle to avoid the production of antibodies against meiotic and postmeiotic germ cells. Studies have demonstrated that some unlikely partners, namely adhesion protein complexes (e.g., occludin-ZO-1, N-cadherin-β-catenin, claudin-5-ZO-1), steroids (e.g., testosterone, estradiol-17β), nonreceptor protein kinases (e.g., focal adhesion kinase, c-Src, c-Yes), polarity proteins (e.g., PAR6, Cdc42, 14-3-3), endocytic vesicle proteins (e.g., clathrin, caveolin, dynamin 2), and actin regulatory proteins (e.g., Eps8, Arp2/3 complex), are working together, apparently under the overall influence of cytokines (e.g., transforming growth factor-β3, tumor necrosis factor-α, interleukin-1α). In short, a "new" BTB is created behind spermatocytes in transit while the "old" BTB above transiting cells undergoes timely degeneration, so that the immunological barrier can be maintained while spermatocytes are traversing the BTB. We also discuss recent findings regarding the molecular mechanisms by which environmental toxicants (e.g., cadmium, bisphenol A) induce testicular injury via their initial actions at the BTB to elicit subsequent damage to germ-cell adhesion, thereby leading to germ-cell loss, reduced sperm count, and male infertility or subfertility. Moreover, we also critically evaluate findings in the field regarding studies on drug transporters in the testis and discuss how these influx and efflux pumps regulate the entry of potential nonhormonal male contraceptives to the apical compartment to exert their effects. Collectively, these findings illustrate multiple potential targets are present at the BTB for innovative contraceptive development and for better delivery of drugs to alleviate toxicant-induced reproductive dysfunction in men.

Bone marrow-specific deficiency of nuclear receptor Nur77 enhances atherosclerosis

RATIONALE

Nuclear receptor Nur77, also known as NR4A1, TR3, or NGFI-B, is expressed in human atherosclerotic lesions in macrophages, endothelial cells, T cells and smooth muscle cells. Macrophages play a critical role in atherosclerosis and the function of Nur77 in lesion macrophages has not yet been investigated.

OBJECTIVE

This study aims to delineate the function of Nur77 in macrophages and to assess the effect of bone marrow-specific deficiency of Nur77 on atherosclerosis.

METHODS AND RESULTS

We investigated Nur77 in macrophage polarization using bone marrow-derived macrophages (BMM) from wild-type and Nur77-knockout (Nur77(-/-)) mice. Nur77(-/-) BMM exhibit changed expression of M2-specific markers and an inflammatory M1-phenotype with enhanced expression of interleukin-12, IFNγ, and SDF-1α and increased NO synthesis in (non)-stimulated Nur77(-/-) BMM cells. SDF-1α expression in nonstimulated Nur77(-/-) BMM is repressed by Nur77 and the chemoattractive activity of Nur77(-/-) BMM is abolished by SDF-1α inhibiting antibodies. Furthermore, Nur77(-/-) mice show enhanced thioglycollate-elicited migration of macrophages and B cells. The effect of bone marrow-specific deficiency of Nur77 on atherosclerosis was studied in low density lipoprotein receptor-deficient (Ldlr(-/-)) mice. Ldlr(-/-) mice with a Nur77(-/-)-deficient bone marrow transplant developed 2.1-fold larger atherosclerotic lesions than wild-type bone marrow-transplanted mice. These lesions contain more macrophages, T cells, smooth muscle cells and larger necrotic cores. SDF-1α expression is higher in lesions of Nur77(-/-)-transplanted mice, which may explain the observed aggravation of lesion formation.

CONCLUSIONS

In conclusion, in bone marrow-derived cells the nuclear receptor Nur77 has an anti-inflammatory function, represses SDF-1α expression and inhibits atherosclerosis.

Sex differences in statural growth impairment in Crohn's disease: role of IGF-1

BACKGROUND

Growth impairment in Crohn's disease (CD) is more common in males than females for unknown reasons. Since insulin-like growth factor-1 (IGF-1) is important for statural growth, we hypothesized that IGF-1 levels are lower in males with CD.

METHODS

Sex differences in hormone Z-scores based on chronological age (CA-Z) and bone age (BA-Z) were examined in a cross-sectional study of 82 CD patients <21 years of age (43% female).

RESULTS

IGF-1 CA-Z and BA-Z-scores were 0.50 units (P = 0.04) and 1.24 units (P = 0.003) lower in males. Mean bone age (12.2 years) was lower than chronological age (13.1 years) (P < 0.0001). Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and albumin did not differ by sex (P ≥ 0.08), but were associated with IGF-1 CA-Z and BA-Z-scores (P ≤ 0.02). Insulin-like growth factor binding protein-3 (IGFBP-3) CA-Z and BA-Z-scores were 0.71 units (P = 0.004) and 1.26 units (P < 0.001) lower in males. Inflammatory markers were correlated with sex hormone CA-Z and BA-Z and pituitary hormone BA-Z-scores in males (P ≤ 0.03), but not females (P ≥ 0.25). IGF-1 BA-Z-scores were positively associated with height BA-Z-scores (P = 0.03). Mean height BA-Z-scores were lower in males (P = 0.03).

CONCLUSIONS

Lower IGF-1 levels in males may explain sex differences in growth impairment in CD. Inflammation appears to more adversely affect hormone levels and statural growth in males. Prospective longitudinal studies are needed to further clarify the role of IGF-1 in sex differences in statural growth impairment in pediatric CD.

Association of the testis-specific TRIM/RBCC protein RNF33/TRIM60 with the cytoplasmic motor proteins KIF3A and KIF3B

The Rnf33/Trim60 gene is temporally transcribed in the preimplantation embryo before being silenced at the blastocyst stage but Rnf33 expression is detected in adult testis of the mouse. The putative RNF33 protein is a tripartite motif (TRIM)/RBCC protein composed of a typical RING zinc finger, a B-box 2, two α-helical coiled-coil segments, and a B30.2 domain. As a first step towards the elucidation of the biologic function of RNF33, we aimed in this study to elucidate proteins that associate with RNF33. RNF33-interacting proteins were first derived by the yeast two-hybrid system followed by co-immunoprecipitation assays. Interacting domains were determined by deletion mapping in genetic and biochemical analyzes. RNF33 was shown to interact with the kinesin-2 family members 3A (KIF3A) and 3B (KIF3B) motor proteins in the heterodimeric form known to transport cargos along the microtubule. Domain mapping showed that the RB and B30.2 domains of RNF33 interacted with the respective carboxyl non-motor domains of KIF3A and KIF3B. Since RNF33 interacted with the carboxyl-terminal tail of the KIF3A-KIF3B heterodimer, the motor head section of KIF3A-KIF3B was free and available for association with designated cargo(s) and movement along the microtubule. Data also suggest that RNF33 most likely interacted with KIF3A-KIF3B independent of the adaptor kinesin-associated protein KAP3. This study is a first demonstration of a TRIM protein, namely RNF33, that interacts with the kinesin molecular motors possibly contributing to kinesin-dependent mobilization of specific cargo(s) along the microtubule in the testis of the mouse.

Correlation of sex hormone and androgen receptor with diabetes mellitus in elderly men

AIM

To investigate sex hormone and androgen receptor (AR) levels and to evaluate their relationship with diabetes mellitus (DM) in senile men.

METHODS

The cross-sectional study included 492 elderly men comprising 104 healthy subjects (mean age 71.4 ± 5.2 years), 259 subjects without DM (71.5 ± 5.0 years) and 129 DM patients (73.0 ± 6.3 years). Plasma concentrations of total testosterone (TT), free testosterone (FT), dehydroepiandrosterone sulphate, sex hormone-binding globulin (SHBG), estradiol (E(2)), luteinising hormone) and follicle-stimulating hormone (FSH) were determined. AR-positive cells were measured by flow cytometry.

RESULTS

TT concentrations were significantly lower in the DM group (13.8 ± 4.7 nmol/l) than in the healthy (17.1 ± 6.1 nmol/l) and non-diabetes groups (15.8 ± 6.0 nmol/l; all P < 0.01). FT, SHBG, AR-positive proportion (AR%) and AR fluorescence intensity showed a decreasing trend among the healthy, non-DM and DM groups, but the differences were not significant. TT, E(2), E(2)/testosterone and SHBG were negatively correlated with blood glucose. SHBG was positively correlated and TT and AR% were negatively correlated with the course of DM. Logistic multiple regression analysis revealed that age, waist/hip ratio, FSH, SHBG and AR% are potential risk factors for DM.

CONCLUSIONS

Low levels of TT, SHBG and AR may be potential risk factors for DM in elderly men.

Toll-like receptor-initiated testicular innate immune responses in mouse Leydig cells

The testis is an immunoprivileged site, where the local cell-initiated testicular innate immune responses play a crucial role in defense against microbial infections. Mechanisms modulating the testicular cell-built defense system remain to be clarified. In this article, we demonstrate that Leydig cells, a major cell population in the testicular interstitium, initiate innate immunity through the activation of Toll-like receptors (TLRs). Several TLRs are expressed in mouse Leydig cells; among these, TLR3 and TLR4 are expressed at relatively high levels compared with other TLR members. Both TLR3 and TLR4 can be activated by their agonists (polyinosinic:polycytidylic acid and lipopolysaccharide) in Leydig cells and subsequently induce the production of inflammatory factors, such as IL-1β, IL-6, TNF-α, and type 1 interferons (IFN) (IFN-α and IFN-β). Notably, the activation of TLR3 and TLR4 suppresses steroidogenesis by Leydig cells. Further, we provide evidence that Axl and Mer receptor tyrosine kinases are expressed in Leydig cells and regulate TLR-mediated innate immune responses negatively. Data presented here describe a novel function of Leydig cells in eliciting testicular innate immune responses that should contribute to the protection of the testis from microbial infections.

Magnesium and anabolic hormones in older men

Optimal nutritional and hormonal statuses are determinants of successful ageing. The age associated decline in anabolic hormones such as testosterone and insulin-like growth factor 1 (IGF-1) is a strong predictor of metabolic syndrome, diabetes and mortality in older men. Studies have shown that magnesium intake affects the secretion of total IGF-1 and increase testosterone bioactivity. This observation suggests that magnesium can be a modulator of the anabolic/catabolic equilibrium disrupted in the elderly people. However, the relationship between magnesium and anabolic hormones in men has not been investigated. We evaluated 399 ≥65-year-old men of CHIANTI in a study population representative of two municipalities of Tuscany (Italy) with complete data on testosterone, total IGF-1, sex hormone binding globulin (SHBG), dehydroepiandrosterone sulphate (DHEAS) and serum magnesium levels. Linear regression models were used to test the relationship between magnesium and testosterone and IGF-1. Mean age of the population was 74.18 ± 6.43 (years ± SD, age range 65.2-92.4). After adjusting for age, magnesium was positively associated with total testosterone (β ± SE, 34.9 ± 10.3; p = 0.001) and with total IGF-1 (β ± SE, 15.9 ± 4.8; p = 0.001). After further adjustment for body mass index (BMI), log (IL-6), log (DHEAS), log (SHBG), log (insulin), total IGF-1, grip strength, Parkinson's disease and chronic heart failure, the relationship between magnesium and total testosterone remained strong and highly significant (β ± SE, 48.72 ± 12.61; p = 0.001). In the multivariate analysis adjusted for age, BMI, log (IL-6), liver function, energy intake, log (insulin), log (DHEAS), selenium, magnesium levels were also still significantly associated with IGF-1 (β ± SE, 16.43 ± 4.90; p = 0.001) and remained significant after adjusting for total testosterone (β ± SE, 14.4 ± 4.9; p = 0.01). In a cohort of older men, magnesium levels are strongly and independently associated with the anabolic hormones testosterone and IGF-1.

[Clinical symptoms of hypogonadism after radical prostatectomy]

This study checked whether the prevalence of hypogonadal symptoms [measured using the Aging Males' Symptoms Scale (AMSS)] after radical prostatectomy can give information about the prevalence of hypogonadism in this group of patients. Distribution of the level of complaints (no, mild, moderate or severe) on the AMSS after radical prostatectomy (n=576) was analyzed in all patients (G) and stratified by the point in time of data collection [surgery to AMSS less (K1) and more than 1 year (K2)].The total score shows more patients with mild and moderate symptoms in G, K1, and K2 compared with the control (G 57.6 and 23.4%, K1 59.1 and 22.4%, K2 40 and 35.6% vs 36.5 and 11.2%). In the somatic score G and K1 show 2.4% (G) and 1.7% (K1) less patients with no and 1.5% (G) and 0.9% (K1) less patients with little complaints compared with the control; 2.6% (G) and 1.8% (K1) more patients state moderate and 1.2% (G) and 0.8% (K1) more severe complaints. K2 shows fewer patients with no and mild (22.2 and 31.1% vs 33.3 and 39.3%) and more with moderate and severe complaints (33.3 and 13.3% vs 21.0 and 6.4%) compared with the control. In the psychological score patients in G and K1 state less mild complaints (G 33.9%, K1 32.8% vs 41.8%), more patients state no complaints (G 45.8%, K1 47.3% vs 43.6%) as well as moderate and severe complaints (G 12.8%, K1 12.8% vs 10.9% and G 7.5%, K1 7.2% vs 3.7 %) compared with the control. K2 shows more complaints of all levels compared with the control (mild 46.7 vs 41.8%, moderate 13.3 vs 10.9%, and severe 11.1 vs 3.7%). In the sexual score all groups of patients show significantly more severe complaints (G 89.6%, K1 89.5%, K2 91.1% vs 6.1%).Multiple factors influenced by surgery and diagnosis of cancer which are independent of hormonal effects make distribution of hypogonadal symptoms on the AMSS not suitable to give information about the prevalence of hypogonadism after radical prostatectomy. An analysis of serum testosterone seems to be essential.

Nuclear factor kappa B and tumor necrosis factor-alpha modulation of transcription of the mouse testis- and pre-implantation development-specific Rnf33/Trim60 gene

We have previously reported a mouse Rnf33/Trim60 gene that is temporally expressed in the pre-implantation embryo. The Rnf33 structural gene is composed of a short noncoding exon 1 and an intronless coding exon 2. In the present work, Rnf33 was shown to be expressed in the mouse testis and in the testicular cell lines TM3 and TM4. To elucidate Rnf33 transcriptional modulation, a 2.5-kb Rnf33 sequence, inclusive of the upstream regulatory region, exon 1 and the associated intronic sequence, was dissected in transient transfection and luciferase assays. An initiator and an atypical TATA-box were shown to act as the core promoter elements of the gene. Deletion and mutagenesis of the 2.5-kb sequence in luciferase constructs further demonstrated that an intronic and palindromic kappa B (κB) sequence was an important cis element targeted by the nuclear factor-κB (NF-κB) subunits p65/RELA and p50/NFκB1, and also through modulation by tumor necrosis factor α. Transcriptional up-regulation of Rnf33 by NF-κB and tumor necrosis factor-α was directly demonstrated in TM3 and TM4 cells by real-time PCR quantification of the Rnf33 mRNA levels. Small interfering RNA knockdown of p65 and p50 confirmed Rnf33 down-regulation by p65/p50. Spermatogenesis is regulated by a wide range of stimuli, including NF-κB, which, in turn, is regulated by other signals. Hence, demonstration of NF-κB-regulated Rnf33 expression in testicular cells, particularly in Sertoli cells, implicates functional involvement of the putative RNF33 protein in spermatogenesis through association of the RNF33 protein with the microtubule via interaction with kinesin motor proteins, as previously demonstrated [Huang et al., submitted].

NF-kappaB in renal inflammation

The NF-kappaB family of transcription factors regulates the induction and resolution of inflammation. Two main pathways, classical and alternative, control the nuclear translocation of NF-kappaB. Classical NF-kappaB activation is usually a rapid and transient response to a wide range of stimuli whose main effector is RelA/p50. The alternative NF-kappaB pathway is a more delayed response to a smaller range of stimuli resulting in DNA binding of RelB/p52 complexes. Additional complexity in this system involves the posttranslational modification of NF-kappaB proteins and an ever-increasing range of co-activators, co-repressors, and NF-kappaB complex proteins. Collectively, NF-kappaB regulates the expression of numerous genes that play a key role in the inflammatory response during human and experimental kidney injury. Multiple stimuli activate NF-kappaB through the classical pathway in somatic renal cells, and noncanonical pathway activation by TWEAK occurs in acute kidney injury. Under most test conditions, specific NF-kappaB inhibitors tend to reduce inflammation in experimental kidney injury but not always. Although many drugs in current use clinically influence NF-kappaB activation, there are no data regarding specific NF-kappaB inhibition in human kidney disease.

Molecular mechanisms mediating the effect of mono-(2-ethylhexyl) phthalate on hormone-stimulated steroidogenesis in MA-10 mouse tumor Leydig cells

Di-(2-ethylhexyl) phthalate, a widely used plasticizer, and its active metabolite, mono-(2-ethylhexyl) phthalate (MEHP), have been shown to exert adverse effects on the reproductive tract in developing and adult animals. As yet, however, the molecular mechanisms by which they act are uncertain. In the present study, we address the molecular and cellular mechanisms underlying the effects of MEHP on basal and human chorionic gonadotropin (hCG)-stimulated steroid production by MA-10 Leydig cells, using a systems biology approach. MEHP induced dose-dependent decreases in hCG-stimulated steroid formation. Changes in mRNA and protein expression in cells treated with increasing concentrations of MEHP in the presence or absence of hCG were measured by gene microarray and protein high-throughput immunoblotting analyses, respectively. Expression profiling indicated that low concentrations of MEHP induced the expression of a number of genes that also were expressed after hCG stimulation. Cross-comparisons between the hCG and MEHP treatments revealed two genes, Anxa1 and AR1. We suggest that these genes may be involved in a new self-regulatory mechanism of steroidogenesis. The MEHP-induced decreases in hCG-stimulated steroid formation were paralleled by increases in reactive oxygen species generation, with the latter mediated by the Cyp1a1 gene and its network. A model for the mechanism of MEHP action on MA-10 Leydig cell steroidogenesis is proposed.

Anti-steroidogenic factor ARR19 inhibits testicular steroidogenesis through the suppression of Nur77 transactivation

ARR19 (androgen receptor corepressor-19 kDa), a leucine-rich protein whose expression is down-regulated by luteinizing hormone and cAMP, is differentially expressed during the development of Leydig cells and inhibits testicular steroidogenesis by reducing the expression of steroidogenic enzymes. However, the molecular events behind the suppression of testicular steroidogenesis are unknown. In the present study, we demonstrate that ARR19 inhibits the transactivation of orphan nuclear receptor Nur77, which is one of the major transcription factors that regulate the expression of steroidogenic enzyme genes in Leydig cells. ARR19 physically interacts with Nur77 and suppresses Nur77-induced promoter activity of steroidogenic enzyme genes including StAR, P450c17, and 3beta-HSD in Leydig cells. Transient transfection and chromatin immunoprecipitation assays revealed that ARR19-mediated reduced expression of steroidogenic enzyme genes was likely due to the interference of SRC-1 recruitment to Nur77 protein on the promoter of steroidogenic enzyme genes. These findings suggest that ARR19 acts as a novel coregulator of Nur77, in turn regulating Nur77-induced testicular steroidogenesis, and may play an important role in the development and function of testicular Leydig cells.

Nuclear receptors in Leydig cell gene expression and function

Several signals, such as hormones and signaling molecules, have been identified as important regulators of Leydig cell differentiation and function. Conveying these signals and translating them into a genomic response to ensure an accurate physiological output requires the action of a network of transcription factors, including those belonging to the nuclear receptor superfamily. Nuclear receptors regulate expression of genes important for growth, differentiation, development, and homeostasis. Several nuclear receptors, such as steroid hormone receptors (NR3A and NR3C families), are activated upon ligand binding, whereas others, including members of the NR2C, NR2F, and NR4A families, either do not require a ligand or ligands have yet to be identified. Several nuclear receptors (e.g., NR2F2 and NR5A1) have been shown to play essential roles in Leydig cells, whereas for others (e.g., NR2B1 and NR4A1), the assessment of their function has been precluded by the early embryonic lethality associated with null mice or by redundancy mechanisms by other family members. This is now being overcome with the generation of novel approaches, including Leydig cell-specific knockout models. This review provides an overview of the nuclear receptor family of transcription factors as they relate to Leydig cell gene expression and function.

Regulation of spermatogenesis in the microenvironment of the seminiferous epithelium: new insights and advances

Spermatogenesis is a complex biochemical event, involving the participation of the hypothalamus and the pituitary gland via secretion of the hypothalamus hormone GnRH, and two pituitary hormones FSH and LH. Thus, the hypothalamic-pituitary-testicular axis is a crucial regulatory axis for testicular function. Recent studies have shown that in the microenvironment of the seminiferous epithelium, wherein each Sertoli cell supports approximately 30-50 germ cells at different stages of development, locally produced autocrine and paracrine factors are also involved in spermatogenesis, in particular at the level of cell junctions. These cell junctions at the Sertoli-Sertoli and Sertoli-germ cell interface are crucial for coordinating different events of spermatogenesis by sending signals back-and-forth between Sertoli and germ cells, in order to precisely regulate spermatogonial cell renewal by mitosis, cell cycle progression, meiosis, spermiogenesis, germ cell movement across the epithelium, spermiation and germ cell apoptosis. In this minireview, we provide an update on these latest findings for an emerging new concept regarding the presence of a local "apical ectoplasmic specialization-blood-testis barrier-hemidesmosome/basement membrane" functional axis that regulates the events of spermiation and blood-testis barrier (BTB) restructuring via paracrine/autocrine factors and polarity proteins produced locally in the seminiferous epithelium. These findings provide a new window of research for investigators in the field to tackle the functional regulation of spermatogenesis.

Molecular aspects of steroidogenic factor 1 (SF-1)

Steroidogenic factor 1 (SF-1, also called Ad4BP and NR5A1) is a nuclear receptor with critical roles in steroidogenic tissues, as well as in the brain and pituitary. In particular, SF-1 has emerged as an essential regulator of adrenal and gonadal functions and development. In the last few years, our knowledge on SF-1 has increased considerably at all levels, from the gene to the protein, and on its specific roles in different physiological processes. In this review, we discuss the current understanding on SF-1 with focus on the parameters that control the transcriptional capacity of SF-1 and the mechanisms that ensure proper stage- and tissue-specific expression of the gene encoding SF-1.

ROS inhibit the expression of testicular steroidogenic enzyme genes via the suppression of Nur77 transactivation

Steroidogenesis decreases with aging in the testis, whereas the levels of reactive oxygen species (ROS) increase. In addition, ROS have been reported to inhibit testicular steroidogenesis. Here, we investigated the effects of ROS on the transcriptional activity of Nur77, one of the major transcription factors that regulate the expression of steroidogenic enzyme genes. ROS signaling inhibited Nur77 transactivation, which was diminished by either treatment with c-Jun N-terminal kinase (JNK) inhibitor or the expression of a dominant negative form of JNK. This suggests the involvement of JNK signaling, which elevates the expression of c-Jun as well as its phosphorylation in Leydig cells. In transient transfection assays, c-Jun suppressed Nur77 transactivation in a dose-dependent manner. Further studies using c-Jun mutants revealed that the protein level of c-Jun, but not phosphorylation itself, was important for the suppression of Nur77 transactivation. Nur77 directly interacted with c-Jun in vivo, which blocked the DNA binding activity of Nur77. Together, these results suggest that ROS signaling-mediated c-Jun upregulation suppresses the expression of steroidogenic enzyme genes by inhibiting Nur77 transactivation, resulting in the reduction of testicular steroidogenesis. These findings may provide a mechanistic explanation for the age-related decline in testicular steroid hormone production.

Testosterone deficiency, insulin resistance and the metabolic syndrome

Changing lifestyles and an excess of food supply in developed countries have resulted in an increasing prevalence of overweight and obesity. As a consequence, a disorder of complex pathophysiology involving visceral adipose tissue as an endocrine organ, dyslipidemia, insulin resistance and hypertension has emerged-the so-called metabolic syndrome. This disorder can lead to the manifestation of type 2 diabetes mellitus and cardiovascular disease. In men, testosterone deficiency may contribute to the development of the metabolic syndrome. In turn, states of hyperinsulinemia and obesity lead to a reduction of testicular testosterone production. Testosterone has reciprocal effects on the generation of muscle and visceral adipose tissue by influencing the commitment of pluripotent stem cells and by inhibiting the development of preadipocytes. Insulin sensitivity of muscle cells is increased by augmenting mitochondrial capacity and fostering expression of oxidative phosphorylation genes. Testosterone has a protective effect on pancreatic beta cells, which is possibly exerted by androgen-receptor-mediated mechanisms and influence of inflammatory cytokines. As some, but not all, epidemiological and interventional studies indicate, testosterone substitution might be helpful in preventing or attenuating the metabolic syndrome in aging men with late-onset hypogonadism and in hypogonadal patients with type 2 diabetes mellitus, but larger controlled trials are needed to confirm such hypotheses.

Association between SNPs within candidate genes and compounds related to boar taint and reproduction

Background

Boar taint is an unpleasant odour and flavour of the meat from some uncastrated male pigs primarily caused by elevated levels of androstenone and skatole in adipose tissue. Androstenone is produced in the same biochemical pathway as testosterone and estrogens, which represents a particular challenge when selecting against high levels of androstenone in the breeding programme, without simultaneously decreasing levels of other steroids. Detection of single nucleotide polymorphisms (SNPs) associated with compounds affecting boar taint is important both for gaining a better understanding of the complex regulation of the trait and for the purpose of identifying markers that can be used to improve the gain of breeding. The beneficial SNPs to be used in breeding would have the combinational effects of reducing levels of boar taint without affecting fertility of the animals. The aim of this study was to detect SNPs in boar taint candidate genes and to perform association studies for both single SNPs and haplotypes with levels of boar taint compounds and phenotypes related to reproduction.

Results

An association study involving 275 SNPs in 121 genes and compounds related to boar taint and reproduction were carried out in Duroc and Norwegian Landrace boars. Phenotypes investigated were levels of androstenone, skatole and indole in adipose tissue, levels of androstenone, testosterone, estrone sulphate and 17β-estradiol in plasma, and length of bulbo urethralis gland. The SNPs were genotyped in more than 2800 individuals and several SNPs were found to be significantly (LRT > 5.4) associated with the different phenotypes. Genes with significant SNPs in either of the traits investigated include cytochrome P450 members CYP2E1, CYP21, CYP2D6 and CYP2C49, steroid 5α-reductase SRD5A2, nuclear receptor NGFIB, catenin CTNND1, BRCA1 associated protein BAP1 and hyaluronoglucosaminidase HYAL2. Haplotype analysis provided additional evidence for an effect of CYP2E1 on levels of skatole and indole, and for BAP1, HYAL2 and SRD5A2 on levels of androstenone.

Conclusion

The findings in this study indicate that polymorphisms in CYP2E1, CYP21, CYP2D6, CYP2C49, NGFIB and CTNND1 might be used to reduce levels of boar taint without affecting levels of testosterone, estrone sulphate, 17β-estradiol or length of bulbo urethralis gland.

Transcriptional regulation of steroidogenic genes: STARD1, CYP11A1 and HSD3B

Expression of the genes that mediate the first steps in steroidogenesis, the steroidogenic acute regulatory protein (STARD1), the cholesterol side-chain cleavage enzyme, cytochrome P450scc (CYP11A1) and 3beta-hydroxysteroid dehydrogenase/Delta5-Delta4 isomerase (HSD3B), is tightly controlled by a battery of transcription factors in the adrenal cortex, the gonads and the placenta. These genes generally respond to the same hormones that stimulate steroid production through common pathways such as cAMP signaling and common actions on their promoters by proteins such as NR5A and GATA family members. However, there are distinct temporal, tissue and species-specific differences in expression between the genes that are defined by combinatorial regulation and unique promoter elements. This review will provide an overview of the hormonal and transcriptional regulation of the STARD1, CYP11A1 and specific steroidogenic HSD3B genes in the adrenal, testis, ovary and placenta and discuss the current knowledge regarding the key transcriptional factors involved.

Nuclear receptors, testosterone, and posttranslational modifications in human INSL3 promoter activity in testicular Leydig cells

Insulin-like peptide 3 (INSL3) is a hormone produced by fetal and adult Leydig cells of the mammalian testis. During embryonic life INSL3 is required for testicular descent, whereas in adults it is involved in bone metabolism and male germ cell survival. Despite these important roles, the molecular mechanisms regulating INSL3 expression remain poorly understood. So far, two transcription factors have been implicated in INSL3 transcription: the nuclear receptors SF1 and NUR77. Circumstantial evidence also points to a role for androgens. Using transient transfections in MA-10 Leydig cells, we found that testosterone regulates in a time- and dose-dependent manner the human INSL3 promoter. The INSL3 promoter, however, does not contain a classical androgen-responsive element. Testosterone responsiveness was found to be mediated through an element located in the proximal INSL3 promoter, which also contains a NUR77-SF1-binding site. Furthermore, we found that posttranslational modifications, such as phosphorylation and acetylation, modulate transcription factor activity and therefore also contribute to INSL3 promoter activity in Leydig cells. All together, these data provide new insights into the molecular mechanisms regulating INSL3 expression in the mammalian testis.

ARR19 (androgen receptor corepressor of 19 kDa), an antisteroidogenic factor, is regulated by GATA-1 in testicular Leydig cells

ARR19 (androgen receptor corepressor of 19 kDa), which encodes for a leucine-rich protein, is expressed abundantly in the testis. Further analyses revealed that ARR19 was expressed in Leydig cells, and its expression was differentially regulated during Leydig cell development. Adenovirus-mediated overexpression of ARR19 in Leydig cells inhibited testicular steroidogenesis, down-regulating the expression of steroidogenic enzymes, which suggests that ARR19 is an antisteroidogenic factor. Interestingly, cAMP/luteinizing hormone attenuated ARR19 expression in a fashion similar to that of GATA-1, which was previously reported to be down-regulated by cAMP. Sequence analysis of the Arr19 promoter revealed the presence of two putative GATA-1 binding motifs. Further analyses with 5' deletion and point mutants of putative GATA-1 binding motifs showed that these GATA-1 binding sites were critical for high promoter activity. CREB-binding protein coactivated GATA-1 and markedly increased the activity of the Arr19 promoter. Both GATA-1 and CREB-binding proteins occupied the GATA-1 motifs within the Arr19 promoter, which was repressed by cAMP treatment. Altogether, these findings demonstrate that ARR19 is the target gene of GATA-1 and suggest that ARR19 gene expression in testicular Leydig cells is regulated by luteinizing hormone/cAMP signaling via the control of GATA-1 expression, resulting in the control of testicular steroidogenesis.

Gonadal hormones in men with rheumatoid arthritis--from onset through 2 years

OBJECTIVE

To evaluate changes over a 2-year course in the hypothalamic-pituitary-gonadal (HPG) axis in men with early rheumatoid arthritis (RA) from start of treatment with disease modifying antirheumatic drugs.

METHODS

Forty-one men with early RA and with joint symptoms less than 1 year were studied. Mean age at inclusion was 53 years and mean disease duration 6 months. They were followed prospectively for 2 years for disease activity [Disease Activity Score 28 (DAS28)], physical impairment (Health Assessment Questionnaire), total serum testosterone, non-sex hormone-binding globulin-bound testosterone, and luteinizing hormone (LH). A group of 131 healthy, medicine-free men served as controls for baseline hormone concentrations.

RESULTS

The men with RA already had mean testosterone levels lower than controls early in the disease course. Patients older than 50 years also had significantly lower LH levels compared with controls, consistent with mild hypogonadotropic hypogonadism. In patients who responded to treatment at the 2-year followup the testosterone levels increased significantly. A decrease in DAS28 during the 2 years correlated significantly with increased testosterone levels (r(s) = -0.46, p = 0.006). LH levels were low and stable and did not correlate with disease activity.

CONCLUSION

In early RA, current inflammation seemed to affect the HPG axis, mainly at the gonadal rather than the hypothalamic-pituitary level. Prospective studies are indicated to determine if low HPG activity may be a cause rather than a consequence of a chronic inflammatory state.

Modulation of steroidogenic enzymes in murine lymphoid organs after immune activation

To study the effects of immune cell activation by a protein antigen or lymphoid tissue derived cytokines on peripheral steroidogenesis activities of 3beta HSD and 17beta HSD was measured in lymphoid organs of control and BSA immunized mice after 3 weeks treatment. We demonstrated the presence of 3betaHSD and 17betaHSD in the lymphoid organs after active immunization. We found elevated serum corticosterone after 3 weeks of antigen administration in presence of CFA and a higher serum IL-6 level that also alter lymphoid tissue cytokine responses like TNF-alpha, IL-12p70, and IL-6, among which IL-12p70 and TNF-alpha down-regulate the activity of steroidogenic enzymes in the thymus during an immune response.

The orphan nuclear receptor Nur77 suppresses endothelial cell activation through induction of IkappaBalpha expression

Endothelial inflammation plays a critical role in the development and progression of cardiovascular disease, albeit the mechanisms need to be fully elucidated. Nur77 is highly expressed in vascular endothelial cells (ECs) and plays a role in the regulation of cell proliferation and angiogenesis; its role in vascular inflammation, however, remains unknown. Treatment of human umbilical vein ECs (HUVECs) with tumor necrosis factor (TNF)-alpha substantially increased the transcription and protein expression of Nur77 in a dose and time-dependent manner, as determined by Northern blot and Western blot analysis. Adenovirus mediated overexpression of Nur77 markedly increased the intracellular levels of IkappaBalpha by approximately 4-fold, whereas overexpression of dominant negative Nur77 (DN-Nur77), which lacks its transactivation domain, had no effect on IkappaBalpha expression, suggesting that Nur77 is an important transcriptional factor in controlling IkappaBalpha expression in ECs. Furthermore, overexpression of Nur77 significantly increased IkappaBalpha promoter activity via directly binding to a Nur77 response element in the IkappaBalpha promoter. Importantly, overexpression of Nur77, but not DN-Nur77, protected ECs against the TNF-alpha- and interleukin-1beta-induced endothelial activation, as characterized by attenuation in the nuclear factor kappaB activation, expression of adhesion molecules ICAM-1 and VCAM-1, and monocytic adherence to ECs. These results indicate that Nur77 negatively regulates the TNF-alpha- and interleukin-1beta-induced vascular EC activation by transcriptionally upregulation of IkappaBalpha expression.

Regulation of P450c17 expression in the early embryo depends on GATA factors

The enzyme P450c17 is required for glucocorticoid, sex steroid, and some neurosteroid biosynthesis. Defective human P450c17 causes sexual infantilism and 46,XY sex reversal but is compatible with life, whereas ablation of the corresponding mouse gene causes embryonic lethality at around E7. Normal mouse embryos express P450c17 protein and activity in the embryonic endoderm at E7. Adult adrenal and gonadal steroidogenesis requires steroidogenic factor-1 (SF-1), but SF-1 is not expressed in the early mouse embryo. We show that P450c17 is expressed in differentiated mouse parietal and visceral endoderm lineages, in cultured mouse F9 embryonic carcinoma stem cells, in mouse embryonic stem cells, and in cultured mouse P19 stem cells. Bases -110 to -55 (which contain an SF-1 site and two potential GATA sites) of the rat cyp17 gene confer promoter activity in F9 cells. Overexpression of SF-1 has no effect, whereas overexpression of GATA4 in F9 cells increases transcription from -110/-55 fused to a reporter and increases endogenous P450c17 mRNA. Chromatin immunoprecipitation assays show that GATA4 binds to -215/+55 of mouse cyp17. Stimulating F9 cells with retinoic acid and cAMP differentiates them into visceral and parietal endoderm. Commensurate with cell differentiation, quantitative PCR showed increased GATA4 and GATA6 mRNAs, temporally followed by increased P450c17 mRNA. Small interfering RNA inhibition of GATA4 or GATA6 in undifferentiated or differentiated F9 cells diminished endogenous cyp17 expression. Thus, P450c17 is expressed in mouse embryonic stem cells, its expression increases upon differentiation to an early embryonic endoderm lineage, and GATA4/6 are responsible for activation of P450c17 gene expression at this early stage of embryonic development.

Inflammatory networks in the control of spermatogenesis : chronic inflammation in an immunologically privileged tissue?

Spermatogenesis is a complex, organized process involving intimate interactions between the developing germ cells and supporting Sertoli cells. The process is also highly regulated. Studies suggest that regulation in the seminiferous epithelium involves molecules normally associated with either immune or inflammatory processes; in particular, interleukin 1a (IL1a), IL6, tumor necrosis factor (TNFa), activin A and nitric oxide (NO). While there is considerable evidence that these inflammatory mediators have effects on spermatogonial and spermatocyte development as well as critical supportive functions of the Sertoli cells, which are undoubtedly of considerable importance during testicular inflammation, there remains some skepticism regarding the significance of these molecules with respect to normal testicular function. Nonetheless, it is evident that expression of these regulators varies across the cycle of the seminiferous epithelium in a consistent manner, with major changes in production coinciding with key events within the cycle. This review summarizes the evidence supporting the hypothesis that inflammatory cytokines play a role in normal testicular spermatogenesis, as well as in the etiology of inflammation induced sub-fertility. The balance of data leads to the striking conclusion that the cycle of the seminiferous epithelium resembles a chronic inflammatory event. This appears to be a somewhat paradoxical assertion, since the testis is an immunologically privileged tissue based on its well-established ability to support grafts with minimal rejection responses. However, it may be argued that local immunoregulatory mechanisms, which confer protection from immunity on both transplanted tissues and the developing spermatogenic cells, are equally necessary to prevent local inflammation responses associated with the spermatogenic process from activating the adaptive immune response.

Extracellular matrix and its role in spermatogenesis

In adult mammalian testes, such as rats, Sertoli and germ cells at different stages of their development in the seminiferous epithelium are in close contact with the basement membrane, a modified form of extracellular matrix (ECM). In essence, Sertoli and germ cells in particular spermatogonia are "resting" on the basement membrane at different stages of the seminiferous epithelial cycle, relying on its structural and hormonal supports. Thus, it is not entirely unexpected that ECM plays a significant role in regulating spermatogenesis, particularly spermatogonia and Sertoli cells, and the blood-testis barrier (BTB) constituted by Sertoli cells since these cells are in physical contact with the basement membrane. Additionally, the basement membrane is also in close contact with the underlying collagen network and the myoid cell layers, which together with the lymphatic network, constitute the tunica propria. The seminiferous epithelium and the tunica propria, in turn, constitute the seminiferous tubule, which is the functional unit that produces spermatozoa via its interaction with Leydig cells in the interstitium. In short, the basement membrane and the underlying collagen network that create the acellular zone of the tunica propria may even facilitate cross-talk between the seminiferous epithelium, the myoid cells and cells in the interstitium. Recent studies in the field have illustrated the crucial role of ECM in supporting Sertoli and germ cell function in the seminiferous epithelium, including the BTB dynamics. In this chapter, we summarize some of the latest findings in the field regarding the functional role of ECM in spermatogenesis using the adult rat testis as a model. We also high light specific areas of research that deserve attention for investigators in the field.

Neurobiological and neuropsychiatric effects of dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEAS)

DHEA and DHEAS are steroids synthesized in human adrenals, but their function is unclear. In addition to adrenal synthesis, evidence also indicates that DHEA and DHEAS are synthesized in the brain, further suggesting a role of these hormones in brain function and development. Despite intensifying research into the biology of DHEA and DHEAS, many questions concerning their mechanisms of action and their potential involvement in neuropsychiatric illnesses remain unanswered. We review and distill the preclinical and clinical data on DHEA and DHEAS, focusing on (i) biological actions and putative mechanisms of action, (ii) differences in endogenous circulating concentrations in normal subjects and patients with neuropsychiatric diseases, and (iii) the therapeutic potential of DHEA in treating these conditions. Biological actions of DHEA and DHEAS include neuroprotection, neurite growth, and antagonistic effects on oxidants and glucocorticoids. Accumulating data suggest abnormal DHEA and/or DHEAS concentrations in several neuropsychiatric conditions. The evidence that DHEA and DHEAS may be fruitful targets for pharmacotherapy in some conditions is reviewed.

Effect of tumor necrosis factor-alpha on estrogen metabolism and endometrial cells: potential physiological and pathological relevance

CONTEXT

Estrogen and its metabolites play a critical role in the pathophysiology of the endometrium. The bioavailability of estrogen and estrogen metabolites in endometrial tissues depends on the expression of enzymes involved in estrogen biosynthesis and metabolism. Substantial evidence indicates that estrogen-dependent endometrial disorders are also associated with proinflammatory milieu. However, the mechanism whereby inflammation contributes to these conditions is not known.

OBJECTIVE

The objective of the study was to investigate the effect of TNF-alpha on estrogen metabolism and the expression of estrogen-metabolizing genes in human endometrial glandular epithelial cells (EM1).

DESIGN

EM1 were treated with 17beta-estradiol (E2) with or without TNF-alpha. Capillary liquid chromatography-tandem mass spectrometry analysis was used for quantitative measurement of estrogens and estrogen metabolites. Western blot analysis, reporter gene assay, and real-time RT-PCR were used to assess the expression of estrogen-metabolizing genes.

RESULTS

TNF-alpha treatment significantly increased the level of total estrogen and estrogen metabolites and significantly increased the rate of conversion of estrone (E1) into E2. TNF-alpha also enhanced the oxidative metabolism of estrogen into catecholestrogens with concomitant inhibition of their conversion into methoxyestrogens. Gene expression analysis revealed that TNF-alpha induced the expression of genes involved in E2 biosynthesis (steroidogenic factor-1 and aromatase) and activation (17beta- hydroxysteroid dehydrogenase type 1 and cytochrome P-450, 1B1) with simultaneous repression of genes involved in estrogen inactivation (17beta-hydroxysteroid dehydrogenase type 2; catechol O-methyltransferase; and nicotinamide adenine dinucleotide phosphate-quinone oxidoreductase 1).

CONCLUSION

TNF-alpha increases the local estrogen biosynthesis in human endometrial glandular cells and directs estrogen metabolism into more hormonally active and carcinogenic metabolites. These effects may impact many physiological and pathological processes that occur within the endometrium.

Decreased expression of peroxiredoxin 6 in a mouse model of ethanol consumption

Alcoholic liver disease is multifactorial and oxidative stress is believed to play an intimate role in the initiation and progression of this pathology. The goals of this study were to investigate the effect of chronic ethanol treatment on inducing hepatic oxidative stress and peroxiredoxin 6 expression. After 9 weeks of treatment with an ethanol-containing diet, significant increases in serum ALT activity, liver to body weight ratio, liver triglycerides, CYP2E1 protein expression, and CYP2E1 activity were observed. Chronic ethanol feeding resulted in oxidative stress as evidenced by decreases in hepatic glutathione content and increased deposition of 4-hydroxynonenal and 4-oxononenal protein adducts. In addition, novel findings of decreased PRX6 protein and mRNA and increased levels of carbonylated PRX6 protein were observed in the ethanol-treated animals compared to the pair-fed controls. Lastly, NF-kappaB activity was found to be significantly increased in the ethanol-treated animals. Concurrent with the increase in NF-kappaB activity, decreases in both MEK1/2 and ERK1/2 phosphorylation were also observed in the ethanol-treated animals compared to the pair-fed controls. Together, these data demonstrate that chronic ethanol treatment results in oxidative stress, implicating NF-kappaB activation as an integral mechanism in the negative regulation of PRX6 gene expression in the mouse liver.

The orphan nuclear receptor NUR77 regulates hormone-induced StAR transcription in Leydig cells through cooperation with Ca2+/calmodulin-dependent protein kinase I

Cholesterol transport in the mitochondrial membrane, an essential step of steroid biosynthesis, is mediated by a protein complex containing the steroidogenic acute regulatory (StAR) protein. The importance of this transporter is underscored by mutations in the human StAR gene that cause lipoid congenital adrenal hyperplasia, male pseudohermaphroditism, and adrenal insufficiency. StAR transcription in steroidogenic cells is hormonally regulated and involves several transcription factors. The nuclear receptor NUR77 is present in steroidogenic cells, and its expression is induced by hormones known to activate StAR expression. We have now established that StAR transcription in cAMP-stimulated Leydig cells requires de novo protein synthesis and involves NUR77. We found that cAMP-induced NUR77 expression precedes that of StAR both at the mRNA and protein levels in Leydig cells. In these cells, small interfering RNA-mediated NUR77 knockdown reduces cAMP-induced StAR expression. Chromatin immunoprecipitation assays revealed a cAMP-dependent increase in NUR77 recruitment to the proximal StAR promoter, whereas transient transfections in MA-10 Leydig cells confirmed that NUR77 can activate the StAR promoter and that this requires an element located at -95 bp. cAMP-induced StAR and NUR77 expression in Leydig cells was found to require a Ca2+/calmodulin-dependent protein kinase (CaMK)-dependent signaling pathway. Consistent with this, we show that within the testis, CaMKI is specifically expressed in Leydig cells. Finally, we report that CaMKI transcriptionally cooperates with NUR77, but not steroidogenic factor 1, to further enhance StAR promoter activity in Leydig cells. All together, our results implicate NUR77 as a mediator of cAMP action on StAR transcription in steroidogenic Leydig cells and identify a role for CaMKI in this process.

Nuclear receptors and inflammatory diseases

It is well known that the steroid hormone glucocorticoid and its nuclear receptor regulate the inflammatory process, a crucial component in the pathophysiological process related to human diseases that include atherosclerosis, obesity and type II diabetes, inflammatory bowel disease, Alzheimer's disease, multiple sclerosis, and liver tumors. Growing evidence demonstrates that orphan and adopted orphan nuclear receptors, such as peroxisome proliferator-activated receptors, liver x receptors, the farnesoid x receptor, NR4As, retinoid x receptors, and the pregnane x receptor, regulate the inflammatory and metabolic profiles in a ligand-dependent or -independent manner in human and animal models. This review summarizes the regulatory roles of these nuclear receptors in the inflammatory process and the underlying mechanisms.

Genetic resistance to infection influences a male's sexual attractiveness and modulation of testosterone

Females may be attracted to males genetically resistant to infectious diseases, and one potential mechanism for this mating bias is that such males may be better able to maintain high testosterone. To test these two hypotheses, we collected scent-marks from male house mice (Mus domesticus) genetically resistant and susceptible to Salmonella due to a single locus (Nramp 1, also known as Slc11a1). We tested whether females are more attracted to the scent-marks of resistant males, and whether such males are better able to maintain testosterone concentrations during an experimental Salmonella infection. We found that females preferred the scent-marks of genetically resistant males compared to susceptible ones; but they showed no preferences 5d after males were infected. As predicted, genetically resistant males maintained their testosterone concentrations during the experimental infection, whereas susceptible males showed a significant decline 14 d after inoculation. These differences in the males' ability to modulate testosterone, however, do not explain females' attraction to resistant males. Thus, our results indicate that females sometimes prefer males genetically resistant to infection, and they provide the first evidence that males modulate their testosterone depending upon their genetic resistance to infection; however, we found no evidence to link these two findings.

Increased Expression of the Orphan Nuclear Receptor NURR1 in Psoriasis and Modulation following TNF-α Inhibition

The orphan nuclear receptor NURR1 belongs to the NR4A subfamily of transcription factors which are emerging as important mediators of cytokine and growth factor signaling. The transcriptional function of these ligand-independent and constitutively active receptors is controlled at the level of expression and nuclear localization. This study examines the expression of NURR1 in psoriasis and biological effects on this receptor following inhibition of tumor necrosis factor-alpha (TNF-alpha) signaling. We report increased expression of NURR1 mRNA and protein in involved psoriasis skin compared with uninvolved and normal skin, which correlates significantly (P=0.0055) with clinical measures of the psoriasis area and severity index. Enhanced NURR1 expression localizes to both nucleus and cytoplasm of cells of involved epidermis, blood vessels, and inflammatory infiltrates, in contrast to predominant cytoplasmic distribution in uninvolved and normal skin. Endogenous NURR1 levels are rapidly and selectively increased in response to proinflammatory agonists and growth factors in normal dermal endothelial cells. Following TNF-alpha inhibition with infliximab or etanercept, NURR1 mRNA and protein levels in involved skin are significantly decreased and cytoplasmic distribution is restored. These findings establish the aberrant expression and distribution of NURR1 in psoriasis and suggest that clinical benefits of TNF-alpha inhibition may be mediated through altered NURR1 activity.

Hepatocyte nuclear factor-3 alpha (HNF-3alpha) negatively regulates androgen receptor transactivation in prostate cancer cells

The androgen receptor (AR) is involved in the development and progression of prostate cancers. However, the mechanisms by which this occurs remain incompletely understood. In previous reports, hepatocyte nuclear factor-3alpha (HNF-3alpha) has been shown to be expressed in the epithelia of the prostate gland, and has been determined to regulate the transcription of prostate-specific genes. In this study, we report that HNF-3alpha functions as a novel corepressor of AR in prostatic cells. HNF-3alpha represses AR transactivation on target promoters containing the androgen response element (ARE) in a dose-dependent manner. HNF-3alpha interacts physically with AR, and negatively regulates AR transactivation via competition with AR coactivators, including GRIP1. Furthermore, HNF-3alpha overexpression reduces the androgen-induced expression of prostate-specific antigen (PSA) in LNCaP cells. Taken together, our findings indicate that HNF-3alpha is a novel corepressor of AR, and predict its effects on the proliferation of prostate cancer cells.

Nur77 modulates hepatic lipid metabolism through suppression of SREBP1c activity

NR4A nuclear receptors are induced in the liver upon fasting and regulate hepatic gluconeogenesis. Here, we studied the role of nuclear receptor Nur77 (NR4A1) in hepatic lipid metabolism. We generated mice expressing hepatic Nur77 using adenoviral vectors, and demonstrate that these mice exhibit a modulation of the plasma lipid profile and a reduction in hepatic triglyceride. Expression analysis of >25 key genes involved in lipid metabolism revealed that Nur77 inhibits SREBP1c expression. This results in decreased SREBP1c activity as is illustrated by reduced expression of its target genes stearoyl-coA desaturase-1, mitochondrial glycerol-3-phosphate acyltransferase, fatty acid synthase and the LDL receptor, and provides a mechanism for the physiological changes observed in response to Nur77. Expression of LXR target genes Abcg5 and Abcg8 is reduced by Nur77, and may suggest involvement of LXR in the inhibitory action of Nur77 on SREBP1c expression. Taken together, our study demonstrates that Nur77 modulates hepatic lipid metabolism through suppression of SREBP1c activity.

Improving growth in children with inflammatory bowel disease

BACKGROUND

Growth in children with inflammatory bowel disease (IBD) is affected through a number of mechanisms; controlling disease activity and supporting poor nutritional status are paramount in these patients. Further understanding of the basic mechanisms by which cytokines influence growth will facilitate the development of therapeutic modalities to improve growth.

CONCLUSIONS

Clinical management that addresses growth and puberty in children with IBD should be a partnership between paediatric gastroenterologists and endocrinologists. Well-designed studies of growth-promoting hormonal treatment may answer questions regarding the efficacy and safety of treating growth retardation in the subgroup of patients who continue to fail to grow despite optimal management of their IBD.

Acute sex steroid withdrawal reduces insulin sensitivity in healthy men with idiopathic hypogonadotropic hypogonadism

CONTEXT

Evidence suggests that testosterone (T) influences insulin sensitivity in men. The mechanism of this effect is unclear but is thought to involve changes in body composition.

OBJECTIVE

The aim of this study was to determine whether acute sex steroid withdrawal decreases insulin sensitivity in young, healthy men with idiopathic hypogonadotropic hypogonadism (IHH).

DESIGN

This was a 2-wk prospective study.

SETTING

The study was conducted at a General Clinical Research Center.

PATIENTS

Twelve men with IHH (age 40.8 +/- 2.8 yr) were studied: 1) on hormone replacement with normal T levels and 2) 2 wk after discontinuing therapy.

MAIN OUTCOME MEASURES

Each evaluation comprised a 75-g oral glucose tolerance test with assessment of insulin sensitivity (fasting insulin levels, homeostatic model assessment for insulin resistance, and Matsuda insulin sensitivity index) and insulin secretion (corrected insulin response). Serum cortisol, leptin, adiponectin, free fatty acids, IL-6, C-reactive protein, and TNF-alpha levels were also measured.

RESULTS

Body mass index was unchanged (27.1 +/- 1.1 to 27.2 +/- 1.1 kg/m(2)). Serum T levels decreased from 529 +/- 65 to 28 +/- 8 ng/dl (P < 0.00005). Fasting insulin levels increased from 4.9 +/- 0.7 to 6.2 +/- 0.6 microU/ml (P = 0.005), homeostatic model assessment of insulin resistance increased from 1.07 +/- 0.2 to 1.4 +/- 1.01 (P < 0.005), and insulin sensitivity index decreased from 11.0 +/- 2.3 to 7.5 +/- 0.7 (P < 0.05). There was a trend for fasting glucose levels to increase, 86.7 +/- 1.3 to 90.8 +/- 1.7 mg/dl (P = 0.09). IL-6 levels increased from 1.2 +/- 0.2 to 2.4 +/- 0.5 pg/ml (P < 0.01), whereas TNF-alpha levels decreased from 1.0 +/- 0.1 to 0.6 +/- 0.1 pg/ml (P < 0.05). No other significant changes were observed.

CONCLUSIONS

1) Acute sex steroid withdrawal reduces insulin sensitivity in young healthy IHH men. 2) The acuity of the hypogonadism and absence of changes in body mass index or leptin levels suggest that sex steroids modulate insulin sensitivity in the absence of apparent or detectable changes in body composition.

NR4A nuclear orphan receptors: protective in vascular disease?

PURPOSE OF REVIEW

The nuclear orphan receptors Nur77 (NR4A1), Nurr1 (NR4A2) and NOR-1 (NR4A3) are known to be involved in T-cell apoptosis, brain development, and the hypothalamic-pituitary-adrenal axis. Here, we review our current understanding of the NR4A nuclear receptors in processes that are relevant to vascular disease.

RECENT FINDINGS

NR4A nuclear receptors have recently been described to play a role in metabolism by regulating gluconeogenesis, lipolysis, energy expenditure, and adipogenesis. The function of NR4A nuclear receptors has also extensively been investigated in cells crucial in vascular lesion formation, such as macrophages, endothelial cells and smooth muscle cells.

SUMMARY

The involvement of NR4A nuclear receptors in both metabolism and in processes in the vessel wall supports a substantial role for NR4A nuclear receptors in the development of vascular disease.

Coordinated transcriptional regulation patterns associated with infertility phenotypes in men

INTRODUCTION

Microarray gene-expression profiling is a powerful tool for global analysis of the transcriptional consequences of disease phenotypes. Understanding the genetic correlates of particular pathological states is important for more accurate diagnosis and screening of patients, and thus for suggesting appropriate avenues of treatment. As yet, there has been little research describing gene-expression profiling of infertile and subfertile men, and thus the underlying transcriptional events involved in loss of spermatogenesis remain unclear. Here we present the results of an initial screen of 33 patients with differing spermatogenic phenotypes.

METHODS

Oligonucleotide array expression profiling was performed on testis biopsies for 33 patients presenting for testicular sperm extraction. Significantly regulated genes were selected using a mixed model analysis of variance. Principle components analysis and hierarchical clustering were used to interpret the resulting dataset with reference to the patient history, clinical findings and histological composition of the biopsies.

RESULTS

Striking patterns of coordinated gene expression were found. The most significant contains multiple germ cell-specific genes and corresponds to the degree of successful spermatogenesis in each patient, whereas a second pattern corresponds to inflammatory activity within the testis. Smaller-scale patterns were also observed, relating to unique features of the individual biopsies.

NR4A nuclear receptors in atherosclerosis and vein-graft disease

Nur77, Nurr1, and NOR-1 form the NR4A subfamily of the nuclear hormone receptor superfamily of transcription factors and have been described in the regulation of differentiation, proliferation, apoptosis, and survival of many different cell types. The expression of NR4A nuclear receptors in vascular pathologies has only recently been revealed, after which studies on the functional involvement of NR4A receptors in vascular disease were initiated. This review summarizes our current view on involvement of Nur77, Nurr1, and NOR-1 in atherosclerotic vascular disease and discusses NR4A function in vascular response to injury.

Tumor necrosis factor-alpha activates nuclear factor-kappaB but does not regulate progesterone production in cultured human granulosa luteal cells

BACKGROUND

The role of tumor necrosis factor-alpha (TNF-alpha) in granulosa luteal cell function and steroidogenesis is still controversial. Our aim was to examine the steroidogenic response, together with the simultaneous expression and activation of nuclear factor-kappaB (NF-kappaB), in cultured human granulosa luteal cells (GLCs) following administration of TNF-alpha.

MATERIALS AND METHODS

This prospective controlled study was conducted in the Human Reproduction Division at the Institute of Maternal and Child Research, Faculty of Medicine, University of Chile and the San Borja Arriarán Hospital, National Health Service, Santiago, Chile. GLCs were obtained from aspirates of follicles from women undergoing in vitro fertilization (IVF). Thirty-two women undergoing IVF for tubal-factor and/or male-factor infertility participated in this study. Protein levels of NF-kappaB, the NF-kappaB inhibitor IkappaBalpha and steroidogenic acute regulatory protein (StAR) were determined by Western blot and localization of NF-kappaB was studied by indirect immunofluorescence. Progesterone production was determined by radioimmunoassay.

RESULTS

TNF-alpha did not affect the expression of StAR protein or the synthesis of progesterone. NF-kappaB was expressed in the GLCs and activated by TNF-alpha, resulting in degradation of IkappaBalpha and mobilization of the p65 NF-kappaB subunit into the nucleus.

CONCLUSIONS

These results indicate that TNF-alpha did not modulate steroidogenesis in cultured human GLCs. However, NF-kappaB was activated by TNF-alpha. Therefore the activation of NF-kappaB via the TNF-alpha pathway is likely associated with other preovulatory granulosa cell processes important for human ovarian function.

Salivary cortisol and DHEA levels in the Korean population: age-related differences, diurnal rhythm, and correlations with serum levels

PURPOSE

The primary objective of this study was to examine the changes of basal cortisol and DHEA levels present in saliva and serum with age, and to determine the correlation coefficients of steroid concentrations between saliva and serum. The secondary objective was to obtain a standard diurnal rhythm of salivary cortisol and DHEA in the Korean population.

MATERIALS AND METHODS

For the first objective, saliva and blood samples were collected between 10 and 11 AM from 359 volunteers ranging from 21 to 69 years old (167 men and 192 women). For the second objective, four saliva samples (post-awakening, 11 AM, 4 PM, and bedtime) were collected throughout a day from 78 volunteers (42 women and 36 men) ranging from 20 to 40 years old. Cortisol and DHEA levels were measured using a radioimmunoassay (RIA).

RESULTS

The morning cortisol and DHEA levels, and the age- related steroid decline patterns were similar in both genders. Serum cortisol levels significantly decreased around forty years of age (p < 0.001, when compared with people in their 20s), and linear regression analysis with age showed a significant declining pattern (slope=-2.29, t=-4.297, p < 0.001). However, salivary cortisol levels did not change significantly with age, but showed a tendency towards decline (slope=-0.0078, t=-0.389, p=0.697). The relative cortisol ratio of serum to saliva was 3.4-4.5% and the ratio increased with age (slope=0.051, t=3.61, p < 0.001). DHEA levels also declined with age in saliva (slope=-0.007, t=-3.76, p < 0.001) and serum (slope=-0.197 t=-4.88, p < 0.001). In particular, DHEA levels in saliva and serum did not start to significantly decrease until ages in the 40s, but then decreased significantly further at ages in the 50s (p < 0.001, when compared with the 40s age group) and 60s (p < 0.001, when compared with the 50 age group). The relative DHEA ratio of serum to saliva was similar throughout the ages examined (slop=0.0016, t=0.344, p=0.73). On the other hand, cortisol and DHEA levels in saliva reflected well those in serum (r=0.59 and 0.86, respectively, p < 0.001). The highest salivary cortisol levels appeared just after awakening (about two fold higher than the 11 AM level), decreased throughout the day, and reached the lowest levels at bedtime (p < 0.001, when compared with PM cortisol levels). The highest salivary DHEA levels also appeared after awakening (about 1.5 fold higher than the 11 AM level) and decreased by 11 AM (p < 0.001). DHEA levels did not decrease further until bedtime (p=0.11, when compared with PM DHEA levels).

CONCLUSION

This study showed that cortisol and DHEA levels change with age and that the negative slope of DHEA was steeper than that of cortisol in saliva and serum. As the cortisol and DHEA levels in saliva reflected those in serum, the measurement of steroid levels in saliva provide a useful and practical tool to evaluate adrenal functions, which are essential for clinical diagnosis.