Characterization of signaling pathways leading to Fas expression induced by TNF‐α: pivotal role of NF‐κB

The role of SPATA2 in TNF signaling, cancer, and spermatogenesis

The activation of TNF receptors can lead to cell death with a mechanism of cell necrosis regulated genetically and distinct from apoptosis which is defined as necroptosis. Necroptosis has been one of the most studied emerging cell death/signaling pathways in recent years, especially in light of the role of this process in human disease. However, not all regulatory components of TNF signaling have been identified in relation to both physiological and pathological conditions. In 2008, Spata2 (Spermatogenesis-associated protein 2) was identified as one of the seven fundamental genes for the cellular signaling network that regulates necroptosis and apoptosis. This gene had been cloned by our group and named Spata2 as its expression was found to be elevated in the testis compared to other tissues, localized at the Sertoli cell level and FSH-dependent. More recently, it has been demonstrated that deletion of Spata2 gene causes increased inhibin α expression and attenuated fertility in male mice. However, more importantly, five recently published reports have highlighted that SPATA2 is crucial for recruiting CYLD to the TNFR1 signaling complex thus promoting its activation leading to TNF-induced cell death. Loss of SPATA2 increases transcriptional activation of NF-kB and limits TNF-induced necroptosis. Here we will discuss these important findings regarding SPATA2 and, in particular, focus attention on the evidence that suggests a role for this protein in the TNF signaling pathway.

Serum and tissue levels of coenzyme Q10 in pemphigus vulgaris

BACKGROUND

Pemphigus vulgaris (PV) is a debilitating autoimmune blistering disease of the skin and mucous membranes. It occurs due to the action of autoantibodies against various keratinocyte self-antigens. Anti-mitochondrial autoantibodies are detected in patients with PV. Coenzyme Q10 (CoQ10) is a member of the mitochondrial respiratory chain involved in cellular metabolism, including apoptosis. This study aimed to assess the serum and tissue levels of CoQ10 of patients with PV and healthy controls to determine its relevance to the disease pathogenesis.

METHODS

In this case-control study, 20 patients with PV and 20 healthy controls were included. Blood and skin samples were collected for the measurement of CoQ10 levels using ELISA.

RESULTS

CoQ10 was significantly lower in both serum and tissue of patients with PV compared with controls (p = 0.001). Similar results were found when gender subgroups were separately compared. A significant positive correlation was found between serum and tissue CoQ10 levels in controls (p = 0.019, r = 0.521), but not in patients with PV.

CONCLUSION

CoQ10 appears to be one of the parameters affected by the autoimmune response in PV, which may contribute to the tissue damage caused by autoantibodies. The absence of a significant correlation between CoQ10 level and disease severity or duration may be caused by the complex pathophysiological process in PV with multiple autoantibodies against different keratinocyte antigens.

TNF-α inhibits GDNF levels in Sertoli cells, through a NF-κB-dependent, HES1-dependent mechanism

BACKGROUND

Glial cell line-derived neurotrophic factor (GDNF) is a soluble molecule crucial for the regulation of the spermatogonial stem cells (SSC) of the testis. The effects of GDNF on target cells have been extensively described, but mechanisms underlying GDNF regulation are currently under investigation. In the nervous system, GDNF expression is regulated by pro-inflammatory cytokines including lipopolysaccharide (LPS), interleukin 1 beta (IL-1β), and tumor necrosis factor alpha (TNF-α) but the effect of these cytokines on GDNF expression in the testis is unclear.

OBJECTIVES

The aim of the present study was to investigate the impact of TNF-α on GDNF expression levels using primary murine Sertoli cells as experimental model.

MATERIAL AND METHODS

The expression of TNF-α-regulated genes including Gdnf in different culture conditions was determined by real-time PCR. GDNF protein levels were determined by ELISA. The activation of the NF-κb pathway and HES1 levels were assessed by Western Blot analysis and immunofluorescence. HES1 expression was downregulated by RNAi.

RESULTS

In primary Sertoli cells, TNF-α downregulates GDNF levels through a nuclear factor-κB (NF-κB)-dependent mechanism. Mechanistically, TNF-α induces the transcriptional repressor HES1 by a NF-Κb-dependent mechanism, which in turn downregulates GDNF.

DISCUSSION

Under physiological conditions, TNF-α is secreted by germ cells suggesting that this cytokine plays a role in the paracrine control of SSC niche by modulating GDNF levels. HES1, a well-known target of the Notch pathway, is implicated in the regulation of GDNF expression. In Sertoli cells, TNF-α and Notch signaling may converge at molecular level, to regulate the expression of HES1 and HES1- target genes, including GDNF.

CONCLUSIONS

Because of the importance of GDNF for spermatogonial stem cell self-renewal and proliferation, this data may give important insights on how cytokine signals in the testis modulate the expression of niche-derived factors.

Obesity or Overweight, a Chronic Inflammatory Status in Male Reproductive System, Leads to Mice and Human Subfertility

Obesity is frequently accompanied with chronic inflammation over the whole body and is always associated with symptoms that include those arising from metabolic and vascular alterations. On the other hand, the chronic inflammatory status in the male genital tract may directly impair spermatogenesis and is even associated with male subfertility. However, it is still unclear if the chronic inflammation induced by obesity damages spermatogenesis in the male genital tract. To address this question, we used a high fat diet (HFD) induced obese mouse model and recruited obese patients from the clinic. We detected increased levels of tumor necrosis factor (TNF-α), interleukin-6 (IL-6), and NOD-like receptor family pyrin domain containing-3 (NLRP3) in genital tract tissues including testis, epididymis, seminal vesicle, prostate, and serum from obese mice. Meanwhile, the levels of immunoglobulin G (IgG) and corticosterone were significantly higher than those in the control group in serum. Moreover, signal factors regulated by TNF-α, i.e., p38, nuclear factor-κB (NF-κB), Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), and their phosphorylated status, and inflammasome protein NLRP3 were expressed at higher levels in the testis. For overweight and obese male patients, the increased levels of TNF-α and IL-6 were also observed in their seminal plasma. Furthermore, there was a positive correlation between the TNF-α and IL-6 levels and BMI whereas they were inversely correlated with the sperm concentration and motility. In conclusion, impairment of male fertility may stem from a chronic inflammatory status in the male genital tract of obese individuals.

MK2 and Fas receptor contribute to the severity of CNS demyelination

Models of inflammatory or degenerative diseases demonstrated that the protein-kinase MK2 is a key player in inflammation. In this study we examined the role of MK2 in MOG35-55-induced experimental autoimmune encephalomyelitis (EAE), the animal model for multiple sclerosis. In MK2-deficient (MK2-/-) mice we found a delayed onset of the disease and MK2-/- mice did not recover until day 24 after EAE induction. At this day a higher number of leukocytes in the CNS of MK2-/- mice was found. TNFα was not detectable in serum of MK2-/- mice in any stage of EAE, while high TNFα levels were found at day 16 in wild-type mice. Further investigation revealed an increased expression of FasR mRNA in leukocytes isolated from CNS of wild-type mice but not in MK2-/- mice, however in vitro stimulation of MK2-/- splenocytes with rmTNFα induced the expression of FasR. In addition, immunocomplexes between the apoptosis inhibitor cFlip and the FasR adapter molecule FADD were only detected in splenocytes of MK2-/- mice at day 24 after EAE induction. Moreover, the investigation of blood samples from relapsing-remitting multiple sclerosis patients revealed reduced FasR mRNA expression compared to healthy controls. Taken together, our data suggest that MK2 is a key regulatory inflammatory cytokines in EAE and multiple sclerosis. MK2-/- mice showed a lack of TNFα and thus might not undergo TNFα-induced up-regulation of FasR. This may prevent autoreactive leukocytes from apoptosis and may led to prolonged disease activity. The findings indicate a key role of MK2 and FasR in the regulation and limitation of the immune response in the CNS.

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.

Fas/Fas ligand regulation mediates cell death in human Ewing's sarcoma cells treated with melatonin

Background:

Despite recent advances in cancer therapy, the 5-year survival rate for Ewing's sarcoma is still very low, and new therapeutic approaches are necessary. It was found previously that melatonin induces cell death in the Ewing's sarcoma cell line, SK-N-MC, by activating the extrinsic apoptotic pathway.

Methods:

Melatonin actions were analysed by metabolic viability/survival cell assays, flow cytometry, quantitative PCR for mRNA expression, western blot for protein activation/expression and electrophoretic mobility shift assay for transcription factor activation.

Results:

Melatonin increases the expression of Fas and its ligand Fas L, this increase being responsible for cell death induced by the indolamine. Melatonin also produces a transient increase in intracellular oxidants and activation of the redox-regulated transcription factor Nuclear factor-kappaB. Inhibition of such activation prevents cell death and Fas/Fas L upregulation. Cytotoxic effect and Fas/Fas L regulation occur in all Ewing's cell lines studied, and do not occur in the other tumour cell lines studied where melatonin does not induce cell death.

Conclusion:

Our data offers new insights in the study of alternative therapeutic strategies in the treatment of Ewing's sarcoma. Further attention deserves to be given to the differences in the cellular biology of sensitive tumours that could explain the cytotoxic effect of melatonin and the increase in the level of free radicals caused by this molecule, in particular cancer types.

Role of biomaterials, therapeutic molecules and cells for hepatic tissue engineering

Current liver transplantation strategies face severe shortcomings owing to scarcity of donors, immunogenicity, prohibitive costs and poor survival rates. Due to the lengthy list of patients requiring transplant, high mortality rates are observed during the endless waiting period. Tissue engineering could be an alternative strategy to regenerate the damaged liver and improve the survival and quality of life of the patient. The development of an ideal scaffold for liver tissue engineering depends on the nature of the scaffold, its architecture and the presence of growth factors and recognition motifs. Biomimetic scaffolds can simulate the native extracellular matrix for the culture of hepatocytes to enable them to exhibit their functionality both in vitro and in vivo. This review highlights the physiology and pathophysiology of liver, the current treatment strategies, use of various scaffolds, incorporation of adhesion motifs, growth factors and stem cells that can stabilize and maintain hepatocyte cultures for a long period.

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.

Oncolytic poxvirus armed with Fas ligand leads to induction of cellular Fas receptor and selective viral replication in FasR-negative cancer

The TNF superfamily members including Fas ligand and TRAIL have been studied extensively for cancer therapy, including as components of gene therapy. We examined the use of FasL expression to achieve tumor selective replication of an oncolytic poxvirus (vFasL) and explored its biology and therapeutic efficacy for FasR− and FasR+ cancers. Infection of FasR+ normal and MC38 cancer cells by vFasL led to abortive viral replication due to acute apoptosis and subsequently displayed both reduced pathogenicity in non-tumor bearing mice and reduced efficacy in FasR+ tumor-bearing mice. Infection of FasR− B16 cancer cells by vFasL led to efficient viral replication, followed by late induction of FasR and subsequent apoptosis. Treatment with vFasL compared to its parental virus (vJS6) led to increased tumor regression and prolonged survival of mice with FasR− cancer (B16), but not with FasR+ cancer (MC38). The delayed induction of FasR by viral infection in FasR− cells provides for potential increased efficacy beyond the limit of the direct oncolytic effect. FasR induction provides one mechanism for tumor selective replication of oncolytic poxviruses in FasR− cancers with enhanced safety. The overall result is both a safer and more effective oncolytic virus for FasR− cancer.

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].

Coenzyme Q10 counteracts testicular injury induced by sodium arsenite in rats

The protective effect of coenzyme Q10 against testicular toxicity induced by sodium arsenite (10mg/kg/day, orally for two consecutive days) was investigated in rats. Coenzyme Q10 treatment (10mg/kg/day, i.p.) was applied for five consecutive days, starting three days before arsenite administration. Coenzyme Q10 significantly increased serum testosterone level which was reduced by sodium arsenite. Coenzyme Q10 significantly suppressed lipid peroxidation, restored the depleted antioxidant defenses, and attenuated the increases of tumor necrosis factor-α and nitric oxide resulted from arsenic administration. Also, the elevation of arsenic ion, and the reductions of selenium and zinc ions in testicular tissue were mitigated by coenzyme Q10. Histopathological examination showed that testicular injury mediated by arsenic was ameliorated by coenzyme Q10 treatment. Immunohistochemical analysis revealed that coenzyme Q10 significantly decreased the arsenic-induced expression of inducible nitric oxide synthase, nuclear factor-κB, Fas ligand and caspase-3 in testicular tissue. It was concluded that coenzyme Q10 represents a potential therapeutic option to protect the testicular tissue from the detrimental effects of arsenic intoxication.

ASK1 negatively regulates the 26 S proteasome

The 26 S proteasome, composed of the 20 S core and 19 S regulatory particle, plays a central role in ubiquitin-dependent proteolysis. Disruption of this process contributes to the pathogenesis of the various diseases; however, the mechanisms underlying the regulation of 26 S proteasome activity remain elusive. Here, cell culture experiments and in vitro assays demonstrated that apoptosis signal-regulating kinase 1 (ASK1), a member of the MAPK kinase kinase family, negatively regulated 26 S proteasome activity. Immunoprecipitation/Western blot analyses revealed that ASK1 did not interact with 20 S catalytic core but did interact with ATPases making up the 19 S particle, which is responsible for recognizing polyubiquitinated proteins, unfolding them, and translocating them into the 20 S catalytic core in an ATP-dependent process. Importantly, ASK1 phosphorylated Rpt5, an AAA ATPase of the 19 S proteasome, and inhibited its ATPase activity, an effect that may underlie the ability of ASK1 to inhibit 26 S proteasome activity. The current findings point to a novel role for ASK1 in the regulation of 26 S proteasome and offer new strategies for treating human diseases caused by proteasome malfunction.

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.

The importance of the age factor in cancer vaccination at older age

Cancer is an age-related disease, and with the graying of the society there is an increasing need to optimize cancer management and therapy to elderly patients. Vaccine therapy for cancer is less toxic than chemotherapy or radiation and could be, therefore, especially effective in older, more frail cancer patients. However, it has been shown that older individuals do not respond to vaccine therapy as well as younger adults. This has been attributed to T cell unresponsiveness, a phenomenon also observed in cancer patients per se. Therefore, research is needed to establish whether age-specific tumor-immunological variables permit optimal use of cancer vaccines and therapy in the elderly. This review summarizes the current knowledge of T cell unresponsiveness in cancer patients and elderly, and the results of cancer vaccination in preclinical models at young and old age. Finally, new directions that may lead to effective cancer vaccination at older age will be proposed.

Expression patterns and functions of toll-like receptors in mouse sertoli cells

Toll-like receptors (TLRs) play crucial roles in mediating innate and adaptive immunity. Sertoli cells create a microenvironment that protects seminiferous tubules from autoantigens and invading pathogens. Here we examined the expression and potential function of TLR family in mouse Sertoli cells. RT-PCR, Western blotting, and flow cytometry were used to analyze gene expression. Immunofluorescence staining was used to determine activation of nuclear factor-kappaB. ELISA was used to detect secreted cytokines in culture medium. The phagocytosis assay was performed by Oil Red O staining for lipid droplets. We demonstrated that TLR2, TLR3, TLR4, and TLR5 are highly expressed; TLR6, TLR7, and TLR13 are expressed at relatively low level; and TLR1, TLR8, TLR9, TLR11, and TLR12 are not detected in mouse Sertoli cells. We focused our study on the roles of TLR2-TLR5 in Sertoli cells. Our data indicated that TLR2-TLR5 can be activated by their ligands in mouse Sertoli cells and subsequently increase expression of the inflammatory cytokines IL-1alpha, IL-6, and interferon-alpha, and -beta. The augmented expression of the cytokines might be induced by activation of nuclear factor-kappaB. Notably, activation of TLR3 by its ligand, poly (I:C), specifically promoted phagocytosis of apoptotic spermatogenic cells by Sertoli cells. The TLR-induced Sertoli cell phagocytosis was found to be associated with the up-regulation of scavenger receptors. The results suggest that TLRs expressed in mouse Sertoli cells may play roles in defense against invasion of allo- and autoantigens in the seminiferous tubules.

Cancer vaccination: manipulation of immune responses at old age

The incidence of cancer has increased over the last decade, mainly due to an increase in the elderly population. Vaccine therapy for cancer is less toxic than chemotherapy or radiation and could be, therefore, especially effective in older, more frail cancer patients. However, it has been shown that older individuals do not respond to vaccine therapy as well as younger adults. This has been attributed to T-cell unresponsiveness, a phenomenon also observed in cancer patients per se. This review summarizes the current knowledge of impaired T-cell responses in cancer patients and the elderly, and the results of cancer vaccination in preclinical models at young and old age. Finally, various approaches how to manipulate immune responses against cancer by vaccination at older age will be proposed.

A critical role for matrix metalloproteinases in liver regeneration

BACKGROUND

Matrix metalloproteinases (MMPs), tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6) are mediators of liver regeneration. To determine whether MMPs are required for normal hepatic regeneration, we performed 67% hepatectomies on mice treated with a broad-spectrum MMP-inhibitor, and assessed the effect on liver regeneration and urinary MMP activity.

METHODS

Mice were subjected to sham operations, 67% hepatectomy, or 67% hepatectomy plus treatment with the broad-spectrum MMP inhibitor Marimastat. Urine collected preoperatively and for 8 d postoperatively was tested for MMP-2 and MMP-9 activity using zymography. Serum aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, bilirubin, TNF-alpha, IL-6, and hepatocyte growth factor levels were measured. Liver sections were analyzed by CD31 immunohistochemistry and microvessel density. Mitotic index and proliferating cell nuclear antigen labeling index were determined.

RESULTS

The mean regenerating liver weight on postoperative day 8 was 0.72 +/- 0.01 grams for the hepatectomy Marimastat group, and 0.83 +/- 0.02 grams for the hepatectomy control group (P < 0.001). Urinary MMP-9 activity was elevated during hepatic regeneration, and decreased on postoperative day 8 when the liver returned to its preoperative mass. In contrast, urine from hepatectomy Marimastat mice, in which liver regeneration was successfully inhibited, showed consistently low levels of MMP-2 and MMP-9 activity. The hepatectomy Marimastat group also exhibited elevated serum IL-6 levels on post-operative day 8, while serum TNF-alpha soluble receptor II levels were unchanged. Hepatocyte growth factor levels were not significantly different between the control hepatectomy and hepatectomy Marimastat groups at days 2, 4, and 8. Liver microvessel density was reduced in the hepatectomy Marimastat group at day 4. Mitotic index and proliferating cell nuclear antigen index were significantly decreased in the Marimastat hepatectomy group at post-operative day 2.

CONCLUSIONS

The broad-spectrum MMP-inhibitor Marimastat inhibits liver regeneration. Microvessel density is reduced at day 4. Furthermore, urinary MMP-9 is elevated during liver regeneration, and this effect is not observed when regeneration is inhibited by the broad-spectrum MMP-inhibitor Marimastat.

Sertoli cells initiate testicular innate immune responses through TLR activation

TLRs play a crucial role in early host defense against invading pathogens. In the seminiferous epithelium, Sertoli cells are the somatic nurse cells that mechanically segregate germ cell autoantigens by means of the blood-tubular barrier and create a microenvironment that protects germ cells from both interstitial and ascending invading pathogens. The objective of this study was to examine TLR expression and their functional responses to specific agonists in mouse Sertoli cells. We measured the expression of TLR2, TLR4, TLR5, and TLR6 mRNAs and confirmed by FACS analysis the presence of proteins TLR2 and TLR5 on which we focused our study. Stimulation of Sertoli cells with macrophage-activating lipopeptide-2, agonist of TLR2/TLR6, and with flagellin, agonist of TLR5, induces augmented secretion of the chemokine MCP-1. To assess the functional significance of MCP-1 production following TLR stimulation, conditioned medium from either macrophage-activating lipopeptide-2 or flagellin-treated Sertoli cells was tested for in vitro chemotaxis assay, and a significant increase of macrophage migration was observed in comparison with unstimulated conditioned medium. Moreover, we studied the role of NF-kappaB and of MAPKs in regulating TLR-mediated MCP-1 secretion by using inhibitors specific for each transduction pathway and we demonstrated a pivotal role of the IkappaB/NF-kappaB and JNK systems. In addition, TLR2/TLR6 and TLR5 stimulation induces increased ICAM-1 expression in Sertoli cells. Collectively, this study demonstrates the novel ability of Sertoli cells to potentially respond to a wide variety of bacteria through TLR stimulation.

Gene expression study in the juvenile mouse testis: identification of stage-specific molecular pathways during spermatogenesis

A gene expression time course in the juvenile mouse testis was established using cDNA microarrays derived from a variety of isolated testis cell types. In conjunction with the use of four germ cell-deficient mouse models, a stage and cell-type classification over nine time points has been obtained and analyzed for differential expression of genes. The expression profiles have been clustered into nine groups and subjected to detailed analysis of associated gene ontology. This has allowed the correlation of particular cellular processes and functions with different expression clusters. Focused analysis of transcripts involved in cell number regulation (apoptosis and proliferation) and their spatiotemporal expression patterns are presented. The findings indicate that for genes involved in both apoptosis and proliferation, several distinct pathways regulating these processes are active in somatic and germ cell lineages.

Proteasomal proteolysis in the adrenergic induction of arylalkylamine-N-acetyltransferase in rat pinealocytes

In this study, we investigated the effect of proteasomal inhibition on the induction of arylalkylamine-N-acetyltransferase (AA-NAT) enzyme in cultured rat pinealocytes, using two proteasome inhibitors, MG132 and clastolactacystin beta-lactone (c-lact). Addition of c-lact or MG132 3 h after norepinephrine (NE) stimulation produced a significant increase in AA-NAT protein level and enzyme activity. However, when the proteasome inhibitors were added before or together with NE, significant reductions of the NE-induced aa-nat mRNA, protein, and enzyme activity were observed. A similar inhibitory effect of MG132 on aa-nat transcription was observed when cells were stimulated by dibutyryl cAMP, indicating an effect distal to a post-cAMP step. The inhibitory effect of MG132 on adrenergic-induced aa-nat transcription was long lasting because it remained effective after 14 h of washout and appeared specific for aa-nat because the induction of another adrenergic-regulated gene, MAPK phosphatase-1, by NE was not affected. Time-profile studies revealed that the inhibitory effect of MG132 on NE-stimulated aa-nat induction was detected after 1 h, suggesting accumulation of a protein repressor as a possible mechanism of action. This possibility was also supported by the finding that the inhibitory effect of c-lact on NE-induced aa-nat induction was markedly reduced by cycloheximide, a protein synthesis inhibitor. Together, these results support an important role of proteasomal proteolysis in the adrenergic-mediated induction of aa-nat transcription through its effect on a protein repressor.

Estrogens up-regulate the Fas/FasL apoptotic pathway in lactotropes

The Fas/FasL system provides the major apoptotic mechanism for many cell types, participating in cell turnover in hormone-dependent tissues. In the present study, we localized both Fas and FasL in anterior pituitary cells, mainly in lactotropes and somatotropes. The percentage of anterior pituitary cells showing immunoreactivity for Fas or FasL was higher in cells from rats killed in proestrus than in diestrus. Also, the proportion of pituitary cells from ovariectomized (OVX) rats expressing Fas or FasL increased in the presence of 17beta-estradiol (10(-9) M). This steroid increased the percentage of lactotropes with immunoreactivity for Fas or FasL and the percentage of somatotropes expressing Fas. Activation of Fas by an agonist anti-Fas antibody (Mab-Fas) decreased the vi-ability-3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT assay)-of anterior pituitary cells from OVX rats cultured in the presence of 17beta-estradiol. Also, membrane-bound FasL decreased cell viability-[3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] assay (MTS assay)-only when anterior pituitary cells from OVX rats were incubated with 17beta-estradiol. Moreover, FasL increased the percentage of hypodiploid anterior pituitary cells (flow cytometry). Mab-Fas increased the percentage of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling (TUNEL)-positive pituitary cells and lactotropes from OVX rats only when cells were incubated in the presence of 17beta-estradiol. Also, Mab-Fas triggered apoptosis of anterior pituitary cells from rats killed at proestrus but not at diestrus. Our results show that 17beta-estradiol up-regulates the expression of the Fas/FasL system in anterior pituitary cells and increases Fas-induced apoptosis in lactotropes, suggesting that Fas-induced apoptosis could be involved in the pituitary cell renewal during the estrous cycle.