NF-kappaB and TNF-alpha stimulate androgen receptor expression in Sertoli cells

Serial frequent or multiple Tru-cut® testicular biopsies in rams enable assessment of histological characteristics or transcriptional profiles, with no acute or chronic adverse effects

This study aimed to evaluate the feasibility of performing multiple testicular biopsies in rams using Tru-cut® needles, assessing histological structure, gene expression, and potential complications such as effects on semen quality, testicular blood flow, and ultrasonographic echotexture. In Exp. 1, six mature rams underwent testicular biopsies at intervals (0, 3, 6, 12, 24, and 48 h) using a 16 G Tru-cut® needle, with alternating testes for each collection. Benzathine benzylpenicillin and flunixin meglumine were administered for infection and inflammation control. Local anesthesia and post-biopsy care included lidocaine, digital pressure, and ice application. Testicular samples were analyzed for gene expression related to inflammation, oxidative stress, and steroidogenesis. Semen quality was assessed pre-biopsy and 28 days post-biopsy. Ultrasonographic evaluations of the scrotum and testes were conducted before biopsies and on days 5, 9, 13, 17, and 21 post-biopsies. In Exp. 2, a second group of six mature rams underwent biopsies using 14 G needles, with two samples taken from each testis. Samples were histologically examined for structural preservation. Scrotal skin temperature was measured using infrared thermography, and testicular blood flow was assessed via color Doppler ultrasonography, with measurements taken before and on days 1, 2, 4, 6, 8, 10, 25, 50, 75, and 100 post-biopsies. Semen collection followed the same schedule as in Exp. 1. In Exp. 3, biopsies were performed on different testicular regions (upper, middle, lower) using 12 G, 14 G, and 16 G needles to compare structural preservation. Samples were histologically analyzed. No clinical signs of injury, inflammation, or fluid accumulation were observed. Scrotal pain, increased temperature, swelling, and bleeding were absent, and behavioral signs indicative of pain were not detected. Gene expression remained unchanged, and no significant alterations in seminal characteristics or testicular echogenicity were observed. A slight increase in resistivity and pulsatility indices was noted in Exp. 2. Biopsies with 14 G and 16 G needles resulted in structural disruptions, while 12 G needles better preserved testicular parenchyma. Multiple testicular biopsies using Tru-cut® needles did not cause significant morphological changes, alter transcriptional profiles, or affect semen or ultrasonographic characteristics, demonstrating that this method is viable for monitoring acute molecular changes in the testes.

Thyroxine regulates pig Sertoli cell line proliferation and maturation through the IKK/NFκB and p38 MAPK signaling pathways

The aim of this study was to investigate the signaling pathways involved in the proliferation and differentiation of pig Sertoli cells (SCs) mediated by thyroid hormone (T3) to provide a theoretical and practical basis for enhancing pig semen production. The effects of different concentrations of T3 on the proliferation of pig SCs were evaluated using the CCK8 assay. The impact of T3 on the proliferation and differentiation of pig SCs was further examined using RNA-seq, qPCR, and Western Blotting techniques. Additionally, the involvement of the p38 MAPK and NFκB pathways in mediating the effects of T3 on SCs proliferation and differentiation was investigated. Our findings revealed a strong correlation between the dosage of T3 and the inhibition of pig SCs proliferation and promotion of maturation. T3 regulated the activation state of the NFκB signaling pathway by upregulating IKKα, downregulating IKKβ, and promoting IκB phosphorylation. Furthermore, T3 facilitated SCs maturation by upregulating AR and FSHR expression while downregulating KRT-18. In conclusion, T3 inhibits pig SCs proliferation and promote pig SCs maturation through the IKK/NFκB and p38 MAPK pathways. These findings provide valuable insights into the mechanisms by which T3 influences the proliferation and maturation of pig SCs.

AR loss in prostate cancer stroma mediated by NF-κB and p38-MAPK signaling disrupts stromal morphogen production

Androgen Receptor (AR) activity in prostate stroma is required to maintain prostate homeostasis. This is mediated through androgen-dependent induction and secretion of morphogenic factors that drive epithelial cell differentiation. However, stromal AR expression is lost in aggressive prostate cancer. The mechanisms leading to stromal AR loss and morphogen production are unknown. We identified TGFβ1 and TNFα as tumor-secreted factors capable of suppressing AR mRNA and protein expression in prostate stromal fibroblasts. Pharmacological and RNAi approaches identified NF-κB as the major signaling pathway involved in suppressing AR expression by TNFα. In addition, p38α- and p38δ-MAPK were identified as suppressors of AR expression independent of TNFα. Two regions of the AR promoter were responsible for AR suppression through TNFα. FGF10 and Wnt16 were identified as androgen-induced morphogens, whose expression was lost upon TNFα treatment and enhanced upon p38-MAPK inhibition. Wnt16, through non-canonical Jnk signaling, was required for prostate basal epithelial cell survival. These findings indicate that stromal AR loss is mediated by secreted factors within the TME. We identified TNFα/TGFβ as two possible factors, with TNFα mediating its effects through NF-κB or p38-MAPK to suppress AR mRNA transcription. This leads to loss of androgen-regulated stromal morphogens necessary to maintain normal epithelial homeostasis.

Polymorphisms of androgens-related genes and idiopathic male infertility in Turkish men

Androgens, testosterone and dihydrotestosterone (DHT) are endocrine regulators of spermatogenesis and act via androgen receptor (AR). The aim of this study was to investigate the association(s) of AR (CAG repeat length), SRD5A2 (rs523349, V89L) and TNF-α (rs1800629, -308G/A) polymorphisms with idiopathic male infertility in Turkish men. This case-control study consisted of 312 men with idiopathic infertility and 113 fertile men. Polyacrylamide gel electrophoresis (PAGE) or PCR-restriction fragment length polymorphism methods were used for genotyping. The mean AR CAG repeat length was significantly longer in infertile men than in fertile men (p = 0.015). However, there was no significant association between the SRD5A2 genotypes (VV, VL and LL) and the risk of infertility (p = 0.516). The genotype frequency and allele distribution of TNF-α -308G/A polymorphism (GG, GA, AA genotypes and G, A alleles) were not associated with male infertility (p = 0.779 and p = 0.743 respectively). AR CAG repeat expansion might be one of the risk factors for idiopathic male infertility in Turkish men. Further studies investigating the association of male infertility with AR CAG, V89L and -308G/A polymorphisms are warranted to understand the possible associations among them.

Sex difference in the interrelationship between TNF-α and oxidative stress status in first-episode drug-naïve schizophrenia

BACKGROUND

Increasing evidence indicates that dysregulated TNF-α and oxidative stress (OxS) contribute to the pathophysiology of schizophrenia. Additionally, previous evidence has demonstrated sex differences in many aspects of schizophrenia including clinical characteristics, cytokines, and OxS markers. However, to the best of our knowledge, there is no study investigating sex differences in the association between TNF-α, the OxS system, and their interaction with clinical symptoms in schizophrenia patients, especially in first-episode drug-naïve (FEDN) patients.

METHODS

A total of 119 FEDN schizophrenia patients and 135 healthy controls were recruited for this study. Serum TNF-α, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), and malondialdehyde (MDA) were measured. The Positive and Negative Syndrome Scale (PANSS) was applied to evaluate psychotic symptoms. Two-way ANOVA, partial correlation analysis, and multivariate regression analysis were performed.

RESULTS

A sex difference in MDA levels was demonstrated only in healthy controls (F = 7.06, pBonferroni = 0.045) and not seen in patients. Furthermore, only male patients had higher MDA levels than male controls (F = 8.19, pBonferroni = 0.03). Additionally, sex differences were observed in the association of TNF-α and MDA levels with psychotic symptoms (all pBonferroni < 0.05). The interaction of TNF-α and MDA was only associated with general psychopathology symptom in male patients (B = - 0.07, p = 0.02).

CONCLUSION

Our results demonstrate the sex difference in the relationship between TNF-α, MDA, and their interaction with psychopathological symptoms of patients with schizophrenia.

Impaired macrophages and failure of steroidogenesis and spermatogenesis in rat testes with cytokines deficiency induced by diacerein

The role of cytokines in testicular function under normal conditions has not been completely understood. Here, we evaluated testicular macrophages (TM), steroidogenesis by Leydig cells (LC) and seminiferous tubules integrity in cytokines-deficient rat testes induced by diacerein, an anti-inflammatory drug that inhibits interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-α). Male rats received daily 100 mg/kg of diacerein (DIAG; n = 8) or saline (CG; n = 8) for 30 days. Serum testosterone (T) levels were measured and the seminiferous tubule (ST) area, epithelial area (EA), frequency of damaged ST and number of Sertoli cells (SC) were evaluated. TUNEL method and immunoreactions for detection of pro-IL-1β, TNF-α, steroidogenic acute regulatory protein (StAR), 17β-hydroxysteroid dehydrogenase (17β-HSD), androgen receptor (AR) and scavenger receptor for hemoglobin-haptoglobin complexes (CD163), a TM marker, were performed. Testicular AR, 17β-HSD and IL-1β levels were detected by Western blot. Data were submitted to Student t test (p ≤ 0.05). In DIAG, T and testicular AR, 17β-HSD and IL-1β levels decreased significantly (p < 0.05). The number of TUNEL-positive interstitial cells increased and LC showed weak StAR, 17β-HSD and AR immunoexpression in association with reduced IL-1β immunoexpression and number of CD163-positive TM in the interstitial tissue from diacerein-treated rats. Numerous damaged ST were found in DIAG, and reduction in the EA were associated with germ cells death. Moreover, the number of SC reduced and weak AR and TNF-α immunoexpression was observed in SC and germ cells, respectively. The cytokines deficiency induced by diacerein impairs TM, LC and spermatogenesis, and points to a role of IL-1β in steroidogenesis under normal conditions. In the ST, the weak AR and TNF-α immunoexpression in SC and germ cells, respectively, reinforces the idea that TNF-α plays a role in the SC androgenic control.

Upsurge in autophagy, associated with mifepristone-treated polycystic ovarian condition, is reversed upon thymoquinone treatment

Polycystic ovarian syndrome (PCOS) is a multi-factorial gynecological endocrine disorder. It affects fertility in women and also predisposes to insulin resistance, type 2 diabetes mellitus, obesity etc. Earlier, significance of autophagy has been explored in PCOS-related metabolic disorders and during normal folliculogenesis. Increasing evidences reveal connection of autophagy with chronic inflammatory behaviour, an associated phenomena in polycystic ovaries. However, understanding of the association of autophagy with PCOS is still obscure. This study reveals that increased autophagy in mifepristone (RU486) treated KK-1 cells and in vivo PCO rat model is characterized by upregulated Androgen Receptor (AR) expression and downregulated PCO biomarker aromatase. The prevalence of autophagy has been observed to be concomitant with increased expression of two autophagic markers Beclin1 and MAP-LC3-II while the autophagy substrate p62/SQSTM1 was downregulated. Immunohistochemical staining revealed increased localization of MAP-LC3 in the compacted granulosa layers of the follicular cysts in the PCO model. The PCO rat models also demonstrated augmented levels of p65, the active subunit of NF-κB, which acts as a transcriptional regulator of several pro-inflammatory factors. NF-κB repressor and anti-inflammatory herbal drug thymoquinone, known to alleviate PCO condition, downregulated autophagy modules substantially. Pre-treatment with thymoquinone upregulated aromatase, reduced AR levels and decreased autophagic markers as well as p65 levels, simulating super-ovulated condition. In conclusion, the anti-inflammatory phytochemical thymoquinone alleviated PCO condition.

Testicular Lmcd1 regulates phagocytosis by Sertoli cells through modulation of NFAT1/Txlna signaling pathway

Increased oxidative stress is well known to cause testicular dysfunction in aging males, but the detailed relationships between aging, oxidative stress, and testicular function remain to be elucidated. LIM and cysteine‐rich domains 1 (LMCD1) regulates fundamentally cellular process by interacting with transcription factors. A recent study has identified Lmcd1 as one of the most upregulated nuclear proteins associated with Sertoli cell (SC) differentiation, raising the possibility that testicular actions of LMCD1 are likely to take place. Herein, we reported that LMCD1 was exclusively expressed in the nuclei of SCs. This expression was regulated by TNF‐α signaling produced by apoptotic germ cells (GCs) and was suppressed by oxidative stress in a STAT3‐dependent manner. Ablation of endogenous LMCD1 expression caused lipid accumulation and senescence in GC co‐incubated SCs. Using a previously validated in vivo siRNA approach, we showed that LMCD1 depletion significantly impaired male fertility by inducing oligozoospermia and asthenospermia. Mechanistically, LMCD1 upregulation was associated with the nuclear enrichment of the nuclear factor of activated T cells 1 (NFAT1), a core component of Ca²⁺/calmodulin‐dependent pathway. LMCD1 facilitated the dephosphorylation and nuclear translocation of NFAT1, which consequently expedited the transactivation of Txlna, a binding partner of the syntaxin family essential for testicular phagocytosis, and thus promoted the removal of apoptotic GCs by phagocytic SCs. Collectively, LMCD1 may operate as a novel pretranscriptional integrator linking SC phagocytosis, lipid homeostasis, and cell senescence.

P38 MAPK and glucocorticoid receptor crosstalk in bronchial epithelial cells

Abstract

p38 MAPK inhibition may have additive and synergistic anti-inflammatory effects when used with corticosteroids. We investigated crosstalk between p38 MAPK inhibitors and corticosteroids in bronchial epithelial cells to investigate synergistic effects on cytokine production and the molecular mechanisms involved. Effects of the p38 MAPK inhibitor BIRB-796 and dexamethasone alone and in combination on LPS, polyI:C or TNFα -induced IL-6, CXCL8 and RANTES were assessed in 16HBEs (human epithelial cell line) and on TNFα-induced IL-6 and CXCL8 in primary human epithelial cells from asthma patients and healthy controls. 16HBEs were used to assess effects of BIRB-796 alone and in combination with dexamethasone on glucocorticoid receptor (GR) activity by reporter gene assay, expression of GR target genes and nuclear localisation using Western blot. The effects of BIRB-796 on TNFα stimulated phosphorylation of p38 MAPK and GR at serine (S) 226 by Western blot. Epithelial levels of phosphorylated p38 MAPK and GR S226 were determined by immunohistochemistry in bronchial biopsies from asthma patients and healthy controls. BIRB-796 in combination with dexamethasone increased inhibition of cytokine production in a synergistic manner. Combination treatment significantly increased GR nuclear localisation compared to dexamethasone alone. BIRB-796 inhibited TNFα-induced p38 MAPK and GR S226 phosphorylation. Phosphorylated GR S226 and p38 MAPK levels were increased in bronchial epithelium of more severe asthma patients. Molecular crosstalk exists between p38 MAPK activation and GR function in human bronchial epithelial cells, which alters GR activity. Combining a p38 MAPK inhibitor and a corticosteroid may demonstrate therapeutic potential in severe asthma.

Key messages

• Combination of corticosteroid and p38 inhibitor in human bronchial epithelial cells

• Combination increased cytokine inhibition synergistically and nuclear GR

• p38 MAPK inhibition reduced TNFα-induced phosphorylation of GR at S226 but not S211

• Phosphorylated GRS226 and p38 is increased in bronchial epithelium in severe asthma

• Combining a p38 inhibitor and a corticosteroid may be effective in asthma treatment

Electronic supplementary material

The online version of this article (10.1007/s00109-020-01873-3) contains supplementary material, which is available to authorized users.

Multiple signaling pathways in Sertoli cells: recent findings in spermatogenesis

The functions of Sertoli cells in spermatogenesis have attracted much more attention recently. Normal spermatogenesis depends on Sertoli cells, mainly due to their influence on nutrient supply, maintenance of cell junctions, and support for germ cells' mitosis and meiosis. Accumulating evidence in the past decade has highlighted the dominant functions of the MAPK, AMPK, and TGF-β/Smad signaling pathways during spermatogenesis. Among these pathways, the MAPK signaling pathway regulates dynamics of tight junctions and adherens junctions, proliferation and meiosis of germ cells, proliferation and lactate production of Sertoli cells; the AMPK and the TGF-β/Smad signaling pathways both affect dynamics of tight junctions and adherens junctions, as well as the proliferation of Sertoli cells. The AMPK signaling pathway also regulates lactate supply. These signaling pathways combine to form a complex regulatory network for spermatogenesis. In testicular tumors or infertile patients, the activities of these signaling pathways in Sertoli cells are abnormal. Clarifying the mechanisms of signaling pathways in Sertoli cells on spermatogenesis provides new insights into the physiological functions of Sertoli cells in male reproduction, and also serves as a pre-requisite to identify potential therapeutic targets in abnormal spermatogenesis including testicular tumor and male infertility.

ETA-mediated anti-TNF-α therapy ameliorates the phenotype of PCOS model induced by letrozole

Chronic inflammation is a typical characteristic of polycystic ovary syndrome (PCOS), in which, tumor necrosis factor (TNF)-α plays an important role. We investigated whether anti-TNF-α therapy can alleviate the core phenotypes of PCOS. In pubertal female Wistar rats, release pellets of letrozole (LET) were administered continuously for 90 days to induce PCOS-like phenotypes, followed by treatment with etanercept (ETA), a TNF-α inhibitor. ETA significantly inhibited increases in body weight and androgen, TNF-α, and MCP-1 levels, excessive recruitment of lipid droplets, altered levels of pre-adipose differentiation markers, and abnormal development of follicles. In addition, TNF-α and testosterone (T) levels in the rat sera were significantly positively correlated. Further experiments were performed to investigate the relationship between TNF-α and androgen. Persistent exposure of the RAW 264.7 cell line to low doses of testosterone significantly enhanced TNF-α expression and activated the NF-κB signaling pathway, which were blocked by ETA. Furthermore, treatment with TNF-α promoted the production of testosterone in KGN granulosa cells by reducing CYP19A1 expression, whereas ETA treatment blocked this process. In conclusion, anti-TNF-α therapy with ETA may be an efficient method to alleviate PCOS, whose underlying mechanism may be associated with its ability to reduce excessive androgen levels.

The potential effects of anabolic-androgenic steroids and growth hormone as commonly used sport supplements on the kidney: a systematic review

BACKGROUND

Anabolic-androgenic steroids and growth hormone are among the most commonly used supplements by sportsmen and sportswomen. The aim of this systematic review is to collect and report available data about renal safety of anabolic-androgenic steroids and growth hormone (GH).

METHODS

The search strategy was in accordance with the PRISMA guideline. Seven databases such as Scopus, Medline, Embase, and ISI Web of Knowledge were searched using keywords, such as "growth hormone", "anabolic-androgenic steroids", and "kidney injury". Articles published from 1950 to December 2017 were considered. Randomized clinical trials, prospective or retrospective human studies, case series as well as case reports, and experimental (in vivo) studies were included. Twenty one clinical and experimental articles were selected (12 for anabolic-androgenic steroids and 9 for GH).

RESULTS

Anabolic-androgenic steroids can affect the kidney in different aspects. They can induce or aggravate acute kidney injury, chronic kidney disease, and glomerular toxicity. These adverse effects are mediated through pathways such as stimulating renin-angiotensin-aldosterone system, enhancing the production of endothelin, producing reactive oxygen species, over-expression of pro-fibrotic and pro-apoptotic mediators (e.g., TGF-β1), as well as inflammatory cytokines (e.g., TNF-α, IL-1b, and IL-6). Although GH may affect the kidney in different aspects, such as size, glomerular filtration rate, and tubule functions, either directly or indirectly, there is no conclusive clinical evidence about its detrimental effects on the kidney in athletes and body builders.

CONCLUSION

Evidence regarding effects of anabolic-androgenic steroids exists; However, GH's exact effect on the kidney at doses used by athletes and body builders has not yet been clarified. Cohort clinical studies with long-term follow-up are warranted in this regard.

Identification of SEPTIN12 as a novel target of the androgen and estrogen receptors in human testicular cells

SEPTIN12 (SEPT12) is a testis-enriched gene that is downregulated in the testis of infertile men with severe spermatogenic defects. While SEPT12 is involved in spermatogenic failure and sperm motility disorder, SEPT12 transcriptional regulation is still unknown. Here we report the promoter region of SEPT12 as a 245 bp segment upstream of the transcription start site. One androgen receptor (AR) and two estrogen receptor α (ERα) binding sites in this region were initially identified by bioinformatics prediction and confirmed by chromatin immunoprecipitation assay. Truncated ERα or AR binding sites decreased the promoter activity, which indicated that the ERα and AR are essential for the SEPT12 promoter. On the other hand, the promoter activity was enhanced by the treatment with 17β-estradiol (E2) and 5α-dihydrotestosterone (5α-DHT). Thus, one androgen and two estrogen hormone responsive elements located in the promoter of SEPT12 gene can regulate SEPT12 expression. Two single nucleotide polymorphisms (SNPs), rs759992 T > C and rs3827527 C > T, were observed in the SEPT12 gene promoter region and were able to decrease the promoter activity. In conclusion, the current work identified the promoter of the human SEPT12 gene and provided key evidence about its transcriptional regulation via E2 and 5α-DHT. Since SEPT12 has an important role in spermatogenesis, SEPT12 expression analysis can be developed as a potential tool for the assessment of environmental or food pollution by hormones or for the evaluation of the risk of endocrine-disrupting chemicals (EDCs) in general.

Loss of connexin43 in murine Sertoli cells and its effect on blood-testis barrier formation and dynamics

Connexin43 (Cx43) is the predominant testicular gap junction protein and in cases of impaired spermatogenesis, Cx43 expression has been shown to be altered in several mammals. Amongst other functions, Cx43 is supposed to regulate junction formation of the blood-testis barrier (BTB). The aim of the present study was to investigate the expression pattern of different tight junction (TJ) proteins of the murine BTB using SC-specific Cx43 knockout mice (SCCx43KO). Adult homozygous male SCCx43KO mice (SCCx43KO-/-) predominantly show an arrest of spermatogenesis and SC-only tubules that might have been caused by an altered BTB assembly, composition or regulation. TJ molecules claudin-3, -5 and -11 were examined in adult wild type (WT) and SCCx43KO-/- mice using immunohistochemistry (IHC) and quantitative real-time PCR (qRT-PCR). In this context, investigation of single tubules with residual spermatogenesis in SCCx43KO-/- mice was particularly interesting to identify a potential Cx43-independent influence of germ cells (GC) on BTB composition and dynamics. In tubules without residual spermatogenesis, a diffuse cytoplasmic distribution pattern for claudin-11 protein could be demonstrated in mutant mice. Nevertheless, claudin-11 seems to form functional TJ. Claudin-3 and -5 could not be detected immunohistochemically in the seminiferous epithelium of those tubules. Correspondingly, claudin-3 and -5 mRNA expression was decreased, providing evidence of generally impaired BTB dynamics in adult KO mice. Observations of tubules with residual spermatogenesis suggested a Cx43-independent regulation of TJ proteins by GC populations. To determine initial BTB formation in peripubertal SCCx43KO-/- mice, immunohistochemical staining and qRT-PCR of claudin-11 were carried out in adolescent SCCx43KO-/- and WT mice. Additionally, BTB integrity was functionally analysed using a hypertonic glucose fixative. These analyses revealed that SCCx43KO-/- mice formed an intact BTB during puberty in the same time period as WT mice, which however seemed to be accelerated.

Tissue control of androgen action: The ups and downs of androgen receptor expression

The hormone testosterone plays crucial roles during male development and puberty and throughout life, as an anabolic regulator of muscle and bone structure and function. The actions of testosterone are mediated, primarily, through the androgen receptor, a member of the nuclear receptor superfamily. The androgen receptor gene is located on the X-chromosome and receptor levels are tightly controlled both at the level of transcription of the gene and post-translationally at the protein level. Sp1 has emerged as the major driver of expression of the androgen receptor gene, while auto-regulation by androgens is associated with both positive and negative regulation in a possible cell-selective manner. Research into the networks of positive and negative regulators of the androgen receptor gene are vital in order to understand the temporal and spatial control of receptor levels and the consequences for healthy aging and disease. A clear understanding of the multiple transcription factors participating in regulation of the androgen receptor gene will likely aid in the development and application of hormone therapies to boast or curb receptor activity.

Functional activity of the porcine Gnrhr2 gene promoter in testis-derived cells is partially conferred by nuclear factor-κB, specificity protein 1 and 3 (SP1/3) and overlapping early growth response 1/SP1/3 binding sites

Unlike the classical gonadotropin-releasing hormone (GnRH1), the second mammalian isoform (GnRH2) is ubiquitously expressed, suggesting a divergent function. Indeed, we demonstrated that GnRH2 governs LH-independent testosterone secretion in porcine testes via interaction with its receptor (GnRHR2) on Leydig cells. Transient transfections with luciferase reporter vectors containing 3009bp of 5' flanking sequence for the porcine Gnrhr2 gene (-3009pGL3) revealed promoter activity in all 15 cell lines examined, including swine testis-derived (ST) cells. Therefore, ST cells were utilized to explore the molecular mechanisms underlying transcriptional regulation of the porcine Gnrhr2 gene in the testis. Reporter plasmids containing progressive 5' deletions of the Gnrhr2 promoter indicated that the -708/-490 region contained elements critical to promoter activity. Electrophoretic mobility shift assays (EMSAs) with radiolabeled oligonucleotides spanning the -708/-490bp region and ST nuclear extracts, identified specific binding complexes for the -513/-490, -591/-571 and -606/-581bp segments of promoter. Antibody addition to EMSAs indicated that the p65 and p52 subunits of nuclear factor-κB (NF-κB) comprised the specific complex bound to the oligonucleotide probe for the -513/-490bp promoter region, specificity protein (SP) 1 and 3 bound the -591/-571bp probe and early growth response 1 (EGR1), SP1 and SP3 bound the -606/-581 radiolabeled oligonucleotide. Transient transfections with vectors containing mutations of the NF-κB (-499/-493), SP1/3 (-582/-575) or overlapping EGR1/SP1/3 (-597/-587) binding sites reduced luciferase activity by 26%, 61% and 56%, respectively (P<0.05). Thus, NF-κB, SP1/3 and overlapping EGR1/SP1/3 binding sites are critical to expression of the porcine Gnrhr2 gene in ST cells.

Smoking attenuated the association between IκBα rs696 polymorphism and defective spermatogenesis in humans

Defective spermatogenesis is prevalent in infertile men, but the molecular mechanisms underlying its aetiology are largely unknown. In this study, a proposed association between IκBα SNPs, smoking-related ROS and sperm quality was investigated. Two polymorphisms in the IκBα gene, rs2233406 and rs696 were genotyped in 342 controls and 338 patients with defective spermatogenesis from a southern Chinese population. The results showed the rs696 AA genotype to be significantly more common (21.60% versus 14.33%, P = 0.013) and the rs696 GG genotype to be significantly rarer (28.99% versus 37.13%, P = 0.024) in the cases than in the controls. After subjects were stratified into smokers and nonsmokers, these differences were only observed in nonsmokers. Further analysis showed the rs696 AA genotype to be significantly closely associated with defective spermatogenesis in all subjects (P = 0.014, OR = 1.647) and in nonsmokers (P = 0.036, OR = 1.889). In a TM3 cell model, exposure to cigarette smoke condensate was found to activate NF-κB luciferase activity and altered transcriptional level of NF-κB pathway genes. In conclusion, this study demonstrates an association between functional polymorphisms of the IκBα rs696 and cigarette smoking with the risk of defective spermatogenesis, suggesting some interaction between the NF-κB signalling pathway and smoking-related ROS in human spermatogenesis.

NF-κB Enhances Androgen Receptor Expression through 5′-UTR Binding in Gingival Cells

Dihydropyridine-induced gingival overgrowth (DIGO) is a side effect observed in patients treated for hypertension. The disease is aggravated by inflammation. Nifedipine (Nif), a dihydropyridine, causes gingival overgrowth by increasing the expression of the androgen receptor (AR). Furthermore, the proinflammatory cytokine interleukin 1β (IL-1β) induces collagen α1(I) expression through the AR in DIGO fibroblasts. These observations prompted us to investigate whether and how nuclear factor kappa B (NF-κB) affects AR expression in DIGO. Therefore, gingival fibroblasts obtained from the tissues of patients with DIGO and healthy subjects were stimulated with IL-1β, Nif, or both. mRNA and protein expression was detected with real-time polymerase chain reaction and Western blotting. High correlation coefficients were observed for the mRNA expression of the AR, connective tissue growth factor, and collagen α1(I) induced by both drugs. Western blot analysis showed that IL-1β and Nif increased and activated NF-κB more in DIGO cells than in healthy cells. An electrophoretic mobility shift assay demonstrated that the promoter and 5′-untranslated regions (5′-UTRs) of the AR gene contains 3 binding sites for the NF-κB p65 subunit. A chromatin immunoprecipitation assay revealed that the NF-κB p65 subunit was associated with AR 5′-UTRs in gingival fibroblasts. A site-directed mutagenesis study indicated that a mutation of NF-κB binding sites reduced Nif- and IL-1β-induced AR promoter activities. Collectively, these data indicate that NF-κB is an essential transcriptional regulator of AR gene expression and thus plays a crucial role in collagen overproduction in DIGO fibroblasts.

Impact of low molecular weight phthalates in inducing reproductive malfunctions in male mice: Special emphasis on Sertoli cell functions

Phthalates are commonly used as plasticizers in a variety of products. Since they have been identified as endocrine-disrupting chemicals (EDCs), effect of phthalates on human health is a major concern. In this study, we evaluated individual as well as combined mixture effects of three low molecular weight phthalates on the reproductive system of male mice, specifically on the Sertoli cell structure and function. In order to analyze the blood testes barrier (BTB) dynamics, primary culture of Sertoli cells from 3-weeks old male mice was used for mimicking typical tight junction structures. Male mice were exposed to long-term (45 days) and combined mixture of three phthalates, diethyl phthalate (DEP), diphenyl phthalate (DPP), and dimethyl isophthalate (DMIP) between pre-pubertal to adult stage. Our data showed significant decrease (p < 0.05) in the rates of transcription of certain prominent Sertoli cell specific genes like transferrin, testin and occludin. Moreover, we also observed significant decreases in the expression of proteins like 3β-HSD, connexin-43 and occludin in testicular lysates of treated animals (p < 0.05). The transmission electron microscopic analysis revealed that the test compounds significantly altered the structural integrity of Sertoli cells. The significant changes of Sertoli cell tight junction structure by test compounds were associated with phosphorylation of ERK. Taken together, our study suggests that low molecular weight phthalates may affect male fertility by altering both structural and functional integrity of Sertoli cells in testes.

On the role of germ cells in mammalian gonad development: quiet passengers or back-seat drivers?

In addition to their role as endocrine organs, the gonads nurture and protect germ cells, and regulate the formation of gametes competent to convey the genome to the following generation. After sex determination, gonadal somatic cells use several known signalling pathways to direct germ cell development. However, the extent to which germ cells communicate back to the soma, the molecular signals they use to do so and the significance of any such signalling remain as open questions. Herein, we review findings arising from the study of gonadal development and function in the absence of germ cells in a range of organisms. Most published studies support the view that germ cells are unimportant for foetal gonadal development in mammals, but later become critical for stabilisation of gonadal function and somatic cell phenotype. However, the lack of consistency in the data, and clear differences between mammals and other vertebrates and invertebrates, suggests that the story may not be so simple and would benefit from more careful analysis using contemporary molecular, cell biology and imaging tools.

Tumor necrosis factor α-mediated restructuring of the Sertoli cell barrier in vitro involves matrix metalloprotease 9 (MMP9), membrane-bound intercellular adhesion molecule-1 (ICAM-1) and the actin cytoskeleton

The mammalian blood-testis barrier (BTB) restructures throughout spermatogenesis, thereby allowing developing germ cells to enter the adluminal compartment of the seminiferous epithelium. Previous studies have shown pro-inflammatory cytokines such as tumor necrosis factor α (TNFα) and interleukin-1α to be important regulators of Sertoli cell barrier/BTB function in vitro and in vivo. In this study, the effects of TNFα on Sertoli cell barrier function were assessed, with emphasis on changes in proteases and cell adhesion molecules following treatment. By immunoblotting and immunohistochemistry, MMP9 was found to be present in germ cells, localizing by and large to spermatocytes and spermatids in the adult rat testis. Following treatment of Sertoli cells with physiologically relevant consecutive doses of recombinant human TNFα (25 ng/ml), the steady-state levels of active-matrix metalloprotease 9 (MMP9), membrane-bound intercellular adhesion molecule (mICAM-1) and androgen receptor increased significantly. TNFα also downregulated the steady-state level of occludin, in agreement with earlier results that showed TNFα to disrupt Sertoli cell barrier/BTB function. In addition, TNFα affected the filamentous actin cytoskeleton in Sertoli cells, which appeared to be mediated by cortactin, a regulator of actin dynamics. Taken collectively, these findings imply that germ cells may be involved in BTB restructuring via the localized production of TNFα. These results also illustrate that barrier restructuring correlated with an increase in Sertoli cell mICAM-1, suggesting that it may be critical for adhesion as germ cells traverse the “opened” BTB.

Role of testosterone in the pathogenesis, progression, prognosis and comorbidity of men with chronic kidney disease

Testosterone deficiency and hypogonadism are common conditions in men with chronic kidney disease (CKD). A disturbed hypothalamic-pituitary-gonadal axis due to CKD is thought to contribute to androgen deficiency. Data from experimental studies support the hypothesis that exogenous administration of testosterone may induce the activation of the renin-angiotensin system (RAS), the production of endothelin and the regulation of anti- or/and proinflammatory cytokines involved in the pathogenesis of hypertension and kidney damage. On the other hand, low testosterone levels in male patients with CKD are paradoxically associated with a higher risk of morbidity and mortality, possibly explained by anemia, osteoporosis and cardiovascular disease. In this article, we present an overview of clinical and experimental studies of the impact of testosterone on the progression and prognosis of male patients with CKD; even today, this remains a controversial issue.

Honokiol inhibits androgen receptor activity in prostate cancer cells

BACKGROUND

We have shown previously that honokiol (HNK), a bioactive component of the medicinal plant Magnolia officinalis, inhibits growth of human prostate cancer cells in vitro and in vivo. However, the effect of HNK on androgen receptor (AR) signaling has not been studied.

METHODS

LNCaP, C4-2, and TRAMP-C1 cells were used for various assays. Trypan blue dye exclusion assay or clonogenic assay was performed for determination of cell viability. The effects of HNK and/or its analogs on protein levels of AR and its target gene product prostate specific antigen (PSA) were determined by western blotting. RNA interference of p53 was achieved by transient transfection. Reverse transcription-polymerase chain reaction was performed for mRNA expression of AR. Nuclear level of AR was visualized by microscopy. Apoptosis was quantified by DNA fragmentation assay or flow cytometry after Annexin V-propidium iodide staining.

RESULTS

HNK and its dichloroacetate analog (HDCA) were relatively more effective in suppressing cell viability and AR protein level than honokiol epoxide or biseugenol. Nuclear translocation of AR stimulated by a synthetic androgen (R1881) was markedly suppressed in the presence of HNK. Downregulation of AR protein resulting from HNK exposure was attributable to transcriptional repression as well as proteasomal degradation. HNK-mediated suppression of AR protein was maintained in LNCaP cells after knockdown of p53 protein. HNK-induced apoptosis was not affected by R1881 treatment.

CONCLUSIONS

The present study demonstrates, for the first time, that HNK inhibits activity of AR in prostate cancer cells regardless of the p53 status.

Differential role of the estrogen receptors ESR1 and ESR2 on the regulation of proteins involved with proliferation and differentiation of Sertoli cells from 15-day-old rats

The aim of the present study was to investigate the role of each estrogen receptors on the regulation of proteins involved with proliferation and differentiation of Sertoli cells from 15-day-old rats. Activation of ESR1 by 17β-estradiol (E2) and ESR1-selective agonist PPT increased CCND1 expression, and this effect was dependent on NF-kB activation. E2 and the ESR2-selective agonist DPN, but not PPT, increased, in a PI3K and CREB-dependent manner, the expression of CDKN1B and the transcription factors GATA-1 and DMRT1. Analyzing the expression of ESR1 and ESR2 in different stages of development of Sertoli cells, we observed that the ESR1/ESR2 ratio decreased with age, and this ratio seems to be important to determine the end of cell proliferation and the start of cell differentiation. In Sertoli cells from 15-day-old rats, the ESR1/ESR2 ratio favors the effect of ESR1 and the activation of this receptor increased [Methyl-(3)H]thymidine incorporation. We propose that in Sertoli cells from 15-day-old rats E2 modulates Sertoli cell proliferation through ESR1/NF-kB-mediated increase of CCND1, and cell cycle exit and differentiation through ESR2/CREB-mediated increase of CDKN1B, GATA-1 and DMRT1. The present study reinforces the important role of estrogen for normal testis development.

Antioxidant function of isoflavone and 3,3'-diindolylmethane: are they important for cancer prevention and therapy?

SIGNIFICANCE

Oxidative stress has been mechanistically linked with aging and chronic diseases, including cancer. In fact, oxidative stress status, chronic disease-related inflammation, and cancer occurred in the aging population are tightly correlated. It is well known that the activation of nuclear factor kappa B (NF-κB) plays important roles in oxidative stress, inflammation, and carcinogenesis. Therefore, targeting NF-κB is an important preventive or therapeutic strategy against oxidative stress, inflammation, and cancer.

RECENT ADVANCES

A variety of natural compounds has been found to reduce oxidative stress through their antioxidant activity. Among them, isoflavone, indole-3-carbinol (I3C), and its in vivo dimeric compound 3,3'-diindolylmethane (DIM) have shown their promising effects on the inhibition of NF-κB with corresponding reduction of oxidative stress.

CRITICAL ISSUES

It has been found that isoflavone, I3C, and DIM could inhibit cancer development and progression by regulating multiple cellular signaling pathways that are related to oxidative stress and significantly deregulated in cancer.

FUTURE DIRECTIONS

The antioxidative and anticancer effects of these natural agents make them strong candidates for chemoprevention and/or therapy against human malignancies. However, more clinical trials are needed to evaluate the effects of isoflavone and DIM for the prevention of cancer development and also for the treatment of cancer either alone or in combination with conventional cancer therapeutics.

The involvement of SIRT1 and transcription factor NF-κB (p50/p65) in regulation of porcine ovarian cell function

The role of either mTOR system/enzyme sirtuin1 (SIRT1) or transcription factor NF-κB in the direct control of ovarian function has not been estabished. The aim of our in vitro experiments was to examine the involvement of SIRT1 and the p65 and p50 subunits of NFκB in control of porcine ovarian granulosa cell functions and the interrelationships between SIRT1, NFκB (p65, p50) 30 and FSH in the ovary. Monolayers of primary granulosa cells were transfected with gene constructs encoding either SIRT1 or p65 and p50, and thereafter cultured with, or without, addition of FSH. The accumulation of markers of proliferation (cyclin B1 and cyclin-dependent protein kinase Cdc2/p34) and proteins p50, p65 and SIRT1 in the cells was detected by using SDS-PAGE/Western immunoblotting and immunocytochemistry. The secretion of progesterone (P4) and insulin-like growth factor I (IGF-I) was measured by using radioimmunoassay. It was observed that transfection of cells with a SIRT1 gene construct promoted accumulation of proliferation markers, Cdc2/p34, cyclin B1, decreased accumulation of p50 and p65 and stimulated release of P4 and IGF-I. Co-transfection of cells with cDNA p50 and cDNA p65 enhanced the accumulation of SIRT1 and the release of P4 but did not influence the release of IGF-I. Adding FSH to the culture medium stimulated accumulation of both subunits of NF-κB, as well as accumulation of Cdc2/p34, cyclin B1 and release of both P4 and IGF-I. The ability of FSH to promote NF-κB accumulation, the similarity of the main effects of FSH, SIRT1 and NF-κB, as well as the inability of NF-κB to substantially modify the the majority of FSH effects suggest that SIRT1/NF-κB system could be a mediator of FSH action on ovarian cell functions. On the other hand, SIRT1 was able to inhibit NF-κB and to change stimulatory the effect of FSH on NF-κB from stimulatory to inhibitory. This could suggest the existence of negative feedback control of FSH/NF-κB system by high amounts of SIRT1. Our observations (1) confirm the previous data on proliferation, P4 and IGF-I release in ovarian cells and their up-regulation by FSH, (2) demonstrate the presence of SIRT1, NF-κB/p50 and NF-κB/p65 in these cells, (3) show for the first time the involvement of SIRT1 and NF-κB in direct control of proliferation and secretory activity of ovarian cells, (4) represent the first data on interrelationships between FSH, SIRT1 and NF-κB within the ovary.

Regulation of activin and inhibin in the adult testis and the evidence for functional roles in spermatogenesis and immunoregulation

Activin A provides a unique link between reproduction and immunity, which is especially significant in the adult testis. This cytokine, together with inhibin B and follistatin acting as regulators of activin A activity, is fundamentally involved in the regulation of spermatogenesis and testicular steroidogenesis. However, activin A also has a much broader role in control of inflammation, fibrosis and immunity. In the Sertoli cell, activin A is regulated by signalling pathways that normally regulate stress and inflammation, signalling pathways that intersect with the classical hormonal regulatory pathways mediated by FSH. Modulation of activin A production and activity during spermatogenesis is implicated in the fine control of the cycle of the seminiferous epithelium. The immunoregulatory properties of activin A also suggest that it may be involved in maintaining testicular immune privilege. Consequently, elevated activin A production within the testis during inflammation and infection may contribute to spermatogenic failure, fibrosis and testicular damage.

Nanoparticles and spermatogenesis: how do nanoparticles affect spermatogenesis and penetrate the blood-testis barrier

Due to the widespread use of nanomaterials in medical, industrial and military applications, the question as to whether nanoparticles (NPs) cause harmful disturbances in human health, especially on the reproductive system, remains a matter of concern. In this review, we focus mainly on the in vivo and in vitro effects of NPs on spermatogenesis at the clinical, cellular and molecular levels. In general, most NPs display adverse effects on spermatogenesis at these various levels; but, some NPs show no adverse effects. However, the mechanism underlying NP disruption of spermatogenesis and penetration of the blood-testis barrier remains unclear. In this review, we raise many hypotheses for experimental testing in order to elucidate the mechanism.

Xenogeneic and endogenous spermatogenesis following transplantation of rat germ cells into testes of immunocompetent mice

Spermatogonial stem cells (SSCs) are the foundation of spermatogenesis, and are characterised by their ability to self-renew and to produce differentiated progeny that form spermatozoa. It has been demonstrated that rat spermatogenesis can occur in the seminiferous tubules of congenitally immunodeficient recipient mice after transplantation of rat SSCs. However, the testis is often viewed as an immune-privileged site in that autoimmunogenic antigens on germ cells do not normally elicit an immune response in situ. In the present study, we tried to transplant rat SSCs into immunocompetent mice after depletion of their own germ cells by means of busulfan. The results showed that some transplanted SSCs could undergo complete spermatogenesis in recipient mouse testes, the rat spermatozoa being detected in 7 of 28 recipient epididymides. A significant increase in mouse spermatozoa was also noted in all 28 epididymides of recipient mice regardless of whether rat spermatozoa were concurrently present or not. These results suggest that transplanted rat SSCs can be tolerated in the testes of immunocompetent mice and that the transplantation of rat SSCs stimulates endogenous spermatogenesis in the recipient mice.

The protective effects of quercetin on the cytotoxicity of atrazine on rat Sertoli-germ cell co-culture

To evaluate the direct effect of atrazine (ATZ) and the protective effect of quercetin (QT) on testicular cells, we used primary cultures of rat Sertoli-germ cells (SGCs). ATZ (232 μm) up-regulated the mRNA expression of GATA-4, androgen receptor (AR), androgen-binding protein (ABP), steroidogenic acute regulatory protein (StAR), cytochrome P450 side-chain cleavage enzyme (CYP11A1), cyclooxygenase-2 (COX-2) and NF-κappaB (NF-κB) and down-regulated the expression of stem cell factor (SCF) mRNA. There was no change on the mRNA expression of oestrogen receptor-alpha (ER-α). Simultaneous supplementation of QT in the culture normalizes the expression of these genes. The stimulatory action of follicle stimulating hormone (10 ng/mL) on ATZ-induced StAR and CYP11A1 mRNA levels were also prevented by QT. Furthermore, ATZ-stimulatory action on AR mRNA was opposed in a dose-dependent manner in the presence of increasing concentrations of QT (10-50 μm).The dislodgement of germ cells from the Sertoli cells monolayer and decrease in SGCs viability was prevented by QT. To show whether or not the disrupted interactions of Sertoli and germ cells impaired spermatogenesis, adult male rats exposed in vivo to ATZ (50 mg/kg b.wt) for 1 week had their daily spermatozoa production (DSP) per gram testis lowered by 30%. DSP was significantly increased in the QT(10 mg/kg) + ATZ-treated rats as compared with the ATZ-treated rats. Taken together, ATZ can alter SGCs expression of spermatogenesis- and steroiodogenesis-related genes resulting in a decrease in sperm production in the testis as well as cell viability. QT might block these molecular events-induced by ATZ thereby protecting testicular Sertoli-germ cells from ATZ-induced toxicity.

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.

Persistent inflammation leads to proliferative neoplasia and loss of smooth muscle cells in a prostate tumor model

In prostate cancers, epidemiological data suggest a link between prostate inflammation and subsequent cancer development, but proof for this concept in a tumor model is lacking. A constitutively active version of IκB kinase 2 (IKK2), which is activated by many inflammatory stimuli, was expressed specifically in the prostate epithelium. Constitutive activation of the IKK2/nuclear factor κB axis was insufficient for prostate transformation. However, in combination with heterozygous loss of phosphatase and tensin homolog, IKK2 activation led to an increase in tumor size, formation of cribriform structures, and increase in fiber in the fibroblastic stroma. This phenotype was coupled with persistent inflammation evoked by chemokine expression in the epithelium and stroma. The hyperplastic and dysplastic epithelia correlated with changes evoked by decreased androgen receptor activation. Conversely, inflammation correlated with stromal changes highlighted by loss of smooth muscle cells around prostate ducts. Despite the loss of the smooth muscle barrier, tumors were rarely invasive in a C57BL/6 background. Data mining revealed that smooth muscle markers are also downregulated in human prostate cancers, and loss of these markers in primary tumors is associated with subsequent metastasis. In conclusion, our data show that loss of smooth muscle and invasiveness of the tumor are not coupled in our model, with inflammation leading to increased tumor size and a dedifferentiated stroma.

NF-κB signaling in prostate cancer: a promising therapeutic target?

Prostate carcinoma (PCa) displays a wide variety of genetic alterations, versatile expression profiles as well as cell surface markers. Despite this heterogeneity, a common treatment for advanced PCa is androgen deprivation therapy (ADT). ADT targets the androgen receptor-a member of the nuclear receptor superfamily-which is required for development and function of the prostate and critical for PCa growth and survival. After an initial regression of the tumor during ADT, a large fraction of tumors progress to so-called castration-resistant prostate carcinoma (CRPca) which is highly resistant toward chemotherapy. The ensuing high mortality rates illustrate the importance of novel therapeutic targets for CRPCa. The transcription factor NF-κB was recently proposed as such a potential target for therapeutic intervention in CRPCa. Although NF-κB is essential for the regulation of innate and adaptive immunity recent data suggest a role of NF-κB in cancer initiation and progression. However, the exact function of NF-κB signaling in PCa is still a matter of debate. Here, we review known roles of NF-κB signaling in PCa and emphasize the crosstalk of NF-κB and androgen receptor signaling. Finally, we discuss potential therapeutic relevance of blocking NF-κB in PCa.

Regulation of Sertoli cell activin A and inhibin B by tumour necrosis factor α and interleukin 1α: interaction with follicle-stimulating hormone/adenosine 3',5'-cyclic phosphate signalling

Regulation of crucial events during spermatogenesis involves dynamic changes in cytokine production and interactions across the cycle of the seminiferous epithelium. Regulation of activin A and inhibin B production by the inflammatory cytokines, tumour necrosis factor α (TNFα) and interleukin 1α (IL1α), alone and in conjunction with FSH or a cAMP analogue (dibutyryl cAMP), was examined in cultures of Sertoli cells from 20-day old rats. Both TNFα and IL1α stimulated activin A secretion and expression of its subunit (β(A)) mRNA, and suppressed inhibin B secretion and expression of its subunit (α and β(B)) mRNAs. The actions of TNFα and IL1α were opposed by FSH and dibutyryl cAMP. Both cytokines inhibited FSH/dibutyryl cAMP-stimulated inhibin B secretion and mRNA expression as well as stem cell factor mRNA expression. Both cytokines also inhibited FSH-induced cAMP production, and reduced baseline FSH receptor mRNA expression. These data highlight the reciprocal relationship that exists between FSH/cAMP signalling and inflammatory cytokine signalling pathways in the control of Sertoli cell function, and production of activin A/inhibin B in particular. It is anticipated that these interactions play important roles in the fine control of events during the cycle of the seminiferous epithelium and in the inhibition of spermatogenesis during inflammation.

Toll-like receptors and signalling in spermatogenesis and testicular responses to inflammation--a perspective

It is self-evident that infection and inflammation in the reproductive tract can inhibit male fertility, but the observation that fertility may also be compromised by systemic inflammation and disease is more difficult to explain. Recent studies implicating microbial pattern-recognition receptors, such as the Toll-like receptors (TLRs), as well as inflammatory cytokines and their signalling pathways, in testicular function have cast new light on this mysterious link between infection/inflammation and testicular dysfunction. It is increasingly evident that signalling pathways normally involved in controlling inflammation play fundamental roles in regulating Sertoli cell activity and responses to reproductive hormones, in addition to promoting immune responses within the testis. Many of the negative effects of inflammation on spermatogenesis may be attributed to elevated production of inflammation-related gene products within the circulation and the testis, which subsequently exert disruptive effects on spermatogenic cell development and survival, as well as the ability of the Sertoli cells to provide support for spermatogenesis. These interactions have important implications for testicular dysfunction and disease, and may eventually provide new opportunities for therapeutic interventions.

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].

A local autocrine axis in the testes that regulates spermatogenesis

Spermiation--the release of mature spermatozoa from Sertoli cells into the seminiferous tubule lumen--occurs by the disruption of an anchoring device known as the apical ectoplasmic specialization (apical ES). At the same time, the blood-testis barrier (BTB) undergoes extensive restructuring to facilitate the transit of preleptotene spermatocytes. While these two cellular events take place at opposite ends of the Sertoli cell epithelium, the events are in fact tightly coordinated, as any disruption in either process will lead to infertility. A local regulatory axis exists between the apical ES and the BTB in which biologically active laminin fragments produced at the apical ES by the action of matrix metalloproteinase 2 can regulate BTB restructuring directly or indirectly via the hemidesmosome. Equally important, polarity proteins play a crucial part in coordinating cellular events within this apical ES-BTB-hemidesmosome axis. Additionally, testosterone and cytokines work in concert to facilitate BTB restructuring, which enables the transit of spermatocytes while maintaining immunological barrier function. Herein, we will discuss this important autocrine-based cellular axis that parallels the hormonal-based hypothalamic-pituitary-testicular axis that regulates spermatogenesis. This local regulatory axis is the emerging target for male contraception.

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.

Immunology of the Testis and Male Reproductive Tract

A large body of evidence points to the existence of a close, dynamic relationship between the immune system and the male reproductive tract, which has important implications for our understanding of both systems. The testis and the male reproductive tract provide an environment that protects the otherwise highly immunogenic spermatogenic cells and sperm from immunological attack. At the same time, secretions of the testis, including androgens, influence the development and mature functions of the immune system. Activation of the immune system has negative effects on both androgen and sperm production, so that systemic or local infection and inflammation compromise male fertility. The mechanisms underlying these interactions have begun to receive the attention from reproductive biologists and immunologists that they deserve, but many crucial details remain to be uncovered. A complete picture of male reproductive tract function and its response to toxic agents is contingent upon continued exploration of these interactions and the mechanisms involved.

Polarity proteins and cell-cell interactions in the testis

In mammalian testes, extensive junction restructuring takes place in the seminiferous epithelium at the Sertoli-Sertoli and Sertoli-germ cell interface to facilitate the different cellular events of spermatogenesis, such as mitosis, meiosis, spermiogenesis, and spermiation. Recent studies in the field have shown that Rho GTPases and polarity proteins play significant roles in the events of cell-cell interactions. Furthermore, Rho GTPases, such as Cdc42, are working in concert with polarity proteins in regulating cell polarization and cell adhesion at both the blood-testis barrier (BTB) and apical ectoplasmic specialization (apical ES) in the testis of adult rats. In this chapter, we briefly summarize recent findings on the latest status of research and development regarding Cdc42 and polarity proteins and how they affect cell-cell interactions in the testis and other epithelia. More importantly, we provide a new model in which how Cdc42 and components of the polarity protein complexes work in concert with laminin fragments, cytokines, and testosterone to regulate the events of cell-cell interactions in the seminiferous epithelium via a local autocrine-based regulatory loop known as the apical ES-BTB-basement membrane axis. This new functional axis coordinates various cellular events during different stages of the seminiferous epithelium cycle of spermatogenesis.

Cytokines and junction restructuring events during spermatogenesis in the testis: an emerging concept of regulation

During spermatogenesis in mammalian testes, junction restructuring takes place at the Sertoli-Sertoli and Sertoli-germ cell interface, which is coupled with germ cell development, such as cell cycle progression, and translocation of the germ cell within the seminiferous epithelium. In the rat testis, restructuring of the blood-testis barrier (BTB) formed between Sertoli cells near the basement membrane and disruption of the apical ectoplasmic specialization (apical ES) between Sertoli cells and fully developed spermatids (spermatozoa) at the luminal edge of the seminiferous epithelium occur concurrently at stage VIII of the seminiferous epithelial cycle of spermatogenesis. These two processes are essential for the translocation of primary spermatocytes from the basal to the apical compartment to prepare for meiosis, and the release of spermatozoa into the lumen of the seminiferous epithelium at spermiation, respectively. Cytokines, such as TNFalpha and TGFbeta3, are present at high levels in the microenvironment of the epithelium at this stage of the epithelial cycle. Since these cytokines were shown to disrupt the BTB integrity and germ cell adhesion, it was proposed that some cytokines released from germ cells, particularly primary spermatocytes, and Sertoli cells, would induce restructuring of the BTB and apical ES at stage VIII of the seminiferous epithelial cycle. In this review, the intricate role of cytokines and testosterone to regulate the transit of primary spermatocytes at the BTB and spermiation will be discussed. Possible regulators that mediate cytokine-induced junction restructuring, including gap junction and extracellular matrix, and the role of testosterone on junction dynamics in the testis will also be discussed.

Transcriptional repression and inhibition of nuclear translocation of androgen receptor by diallyl trisulfide in human prostate cancer cells

PURPOSE

The present study was undertaken to determine the effect of diallyl trisulfide (DATS), a promising cancer chemopreventive constituent of garlic, on androgen receptor (AR) protein expression and function using prostate cancer cells.

EXPERIMENTAL DESIGN

The protein levels of AR and prostate-specific antigen (PSA) were determined by immunoblotting. The effect of DATS treatment on AR mRNA level and AR promoter activity was determined by quantitative reverse transcription-PCR and luciferase reporter assay, respectively. Expression of AR protein in poorly differentiated carcinoma and normal prostate of transgenic adenocarcinoma of mouse prostate (TRAMP) mice was determined by immunohistochemistry. Confocal microscopy was done to determine nuclear translocation of AR. Cell viability was determined by trypan blue dye exclusion assay.

RESULTS

Exposure of prostate cancer cells (LNCaP, C4-2, and TRAMP-C1) to DATS resulted in a concentration-dependent decrease in protein level of AR, which was accompanied by suppression of intracellular and secreted levels of PSA. Structure-activity studies revealed critical roles for allyl groups and the oligosulfide chain length in DATS-mediated down-modulation of AR protein. Quantitative reverse transcription-PCR showed a dose-dependent decrease in AR mRNA level, which correlated with inhibition of AR promoter activity. DATS treatment inhibited synthetic androgen (R1881)-stimulated nuclear translocation of AR in LNCaP/C4-2 cells and proliferation of LNCaP cells. Oral gavage of 2 mg/day DATS (three times per week for 13 weeks) markedly suppressed AR protein level in poorly differentiated prostate cancer in TRAMP mice.

CONCLUSION

The present study shows, for the first time, that DATS treatment suppresses AR function in prostate cancer cells.