Myotube depolarization generates reactive oxygen species through NAD(P)H oxidase; ROS-elicited Ca2+ stimulates ERK, CREB, early genes

Controlled generation of reactive oxygen species (ROS) may contribute to physiological intracellular signaling events. We determined ROS generation in primary cultures of rat skeletal muscle after field stimulation (400 1-ms pulses at a frequency of 45 Hz) or after depolarization with 65 mM K+ for 1 min. Both protocols induced a long lasting increase in dichlorofluorescein fluorescence used as ROS indicator. Addition of diphenyleneiodonium (DPI), an inhibitor of NAD(P)H oxidase, PEG-catalase, a ROS scavenger, or nifedipine, an inhibitor of the skeletal muscle voltage sensor, significantly reduced this increase. Myotubes contained both the p47phox and gp91phox phagocytic NAD(P)H oxidase subunits, as revealed by immunodetection. To study the effects of ROS, myotubes were exposed to hydrogen peroxide (H2O2) at concentrations (100-200 microM) that did not alter cell viability; H2O2 induced a transient intracellular Ca2+ rise, measured as fluo-3 fluorescence. Minutes after Ca2+ signal initiation, an increase in ERK1/2 and CREB phosphorylation and of mRNA for the early genes c-fos and c-jun was detected. Inhibition of ryanodine receptor (RyR) decreased all effects induced by H2O2 and NAD(P)H oxidase inhibitors DPI and apocynin decreased ryanodine-sensitive calcium signals. Activity-dependent ROS generation is likely to be involved in regulation of calcium-controlled intracellular signaling pathways in muscle cells.

Transcriptional pausing caused by NELF plays a dual role in regulating immediate-early expression of the junB gene

Human 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole sensitivity-inducing factor (DSIF) and negative elongation factor (NELF) negatively regulate transcription elongation by RNA polymerase II (RNAPII) in vitro. However, the physiological roles of this negative regulation are not well understood. Here, by using a number of approaches to identify protein-DNA interactions in vivo, we show that DSIF- and NELF-mediated transcriptional pausing has a dual function in regulating immediate-early expression of the human junB gene. Before induction by interleukin-6, RNAPII, DSIF, and NELF accumulate in the promoter-proximal region of junB, mainly at around position +50 from the transcription initiation site. After induction, the association of these proteins with the promoter-proximal region continues whereas RNAPII and DSIF are also found in the downstream regions. Depletion of a subunit of NELF by RNA interference enhances the junB mRNA level both before and after induction, indicating that DSIF- and NELF-mediated pausing contributes to the negative regulation of junB expression, not only by inducing RNAPII pausing before induction but also by attenuating transcription after induction. These regulatory mechanisms appear to be conserved in other immediate-early genes as well.

Identification of Flt3 internal tandem duplications downstream targets by high-throughput immunoblotting protein array system

The receptor tyrosine kinase Flt3 plays an important role in proliferation and survival of hematopoietic cells. Flt3 is the most frequently mutated gene (20-30%) in cases of acutemyeloid leukemia (AML). The majority of Flt3 mutations are internal tandem duplications (ITD) in the juxtamembrane domain of Flt3 receptor. This mutation results in the constitutive activation of STAT5 and Ras/mitogen-activated protein kinase pathways, leading to the aberrant growth of AML cells. In this study, to better understand the mechanisms of Flt3-ITD to the downstream pathways, a high-throughput immunoblotting protein array system was employed. As a result, c-Jun and c-Raf were markedly induced, suggesting that these factors are functional downstream targets of Flt3-ITD.

Cooperative cell transformation by Myc/Mil(Raf) involves induction of AP-1 and activation of genes implicated in cell motility and metastasis

Avian fibroblasts transformed simultaneously by the v-myc and v-mil(raf) oncogenes of acute leukemia and carcinoma virus MH2 contain elevated levels of c-Fos and c-Jun, major components of the transcription factor complex AP-1. To define specific transcriptional targets in these cells, subtractive hybridization techniques were employed leading to the identification of strongly upregulated genes including OPN (osteopontin), 126MRP, and rac2. OPN is a cytokine and cell attachment protein which has been implicated in human tumor progression and metastasis, the calcium binding 126MRP protein is related to the human S100 protein family involved in invasive cell growth, and the Rac2 protein belongs to the Rho family of small GTPases regulating actin reorganization and cell migration. Promoter analysis indicated that OPN activation is mediated by a non-consensus AP-1 binding site located close to the transcription start site. Electrophoretic mobility shift assays, chromatin immunoprecipitation and transcriptional reporter gene analyses showed that c-Fos and c-Jun bind specifically to this site and that c-Fos efficiently transactivates the OPN promoter. High-level expression of OPN, 126MRP, or Rac2 proteins from a retroviral vector led to partial cell transformation, documented by morphological changes and anchorage-independent growth. The specific activation in v-myc/v-mil(raf)-transformed cells of target genes with intrinsic oncogenic potential may provide an explanation for the longstanding observation that concomitant expression of these oncogenes leads to strongly enhanced oncogenicity in vivo and in vitro compared to cell transformation by v-myc or v-mil(raf) alone.

Role of vimentin in regulation of monocyte/macrophage differentiation

Maturation of blood cells depends on dramatic changes of expression profiles of specific genes. Although these changes have been extensively studied, their functional outcomes often remain unclear. In this study, we explored the identity and function of an unknown protein that was greatly overexpressed in v-myb-transformed BM2 monoblasts undergoing differentiation to macrophage-like cells. We identified this protein as vimentin, the intermediate filament protein. We show that an increased level of vimentin protein results from activation of the vimentin gene promoter occurring in monoblastic cells induced to differentiate by multiple agents. Furthermore, our studies reveal that the vimentin gene promoter is stimulated by Myb and Jun proteins, the key transcriptional regulators of myeloid maturation. Silencing of vimentin gene expression using siRNA markedly suppressed the ability of BM2 cells to form macrophage polykaryons active in phagocytosis and producing reactive oxygen species. Taken together, these findings document that up-regulation of vimentin gene expression is important for formation of fully active macrophage-like cells and macrophage polykaryons.

DNA damage, apoptosis and C-myc, C-fos, and C-jun overexpression induced by selenium in rat hepatocytes

OBJECTIVE

To study the effects of selenium on DNA damage, apoptosis and c-myc, c-fos, and c-jun expression in rat hepatocytes.

METHODS

Sodium selenite at the doses of 5, 10, and 20 micromol/kg was given to rats by i.p. and there were 5 male SD rats in each group. Hepatocellular DNA damage was detected by single cell gel electrophoresis (or comet assay). Hepatocellular apoptosis was determined by TUNEL (TdT-mediated dUTP nick end labelling) and flow cytometry. C-myc, c-fos, and c-jun expression in rat hepatocytes were assayed by Northern dot hybridization. C-myc, c-fos, and c-jun protein were detected by immunohistochemical method.

RESULTS

At the doses of 5, 10, and 20 micromol/kg, DNA damage was induced by sodium selenite in rat hepatocytes and the rates of comet cells were 34.40%, 74.80%, and 91.40% respectively. Results also showed an obvious dose-response relationship between the rates of comet cells and the doses of sodium selenite (r=0.9501, P<0.01). Sodium selenite at the doses of 5, 10, and 20 micromol/kg caused c-myc, c-fos, and c-jun overexpression obviously. The positive brown-yellow signal for proteins of c-myc, c-fos, and c-jun was mainly located in the cytoplasm of hepatocytes with immunohistochemical method. TUNEL-positive cells were detected in selenium-treated rat livers. Apoptotic rates (%) of selenium-treated liver cells at the doses of 5, 10, and 20 micromol/kg were (3.72 +/- 1.76), (5.82 +/- 1.42), and (11.76 +/- 1.87) respectively, being much higher than those in the control. Besides an obvious dose-response relationship between apoptotic rates and the doses of sodium selenite (r=0.9897, P<0.01), these results displayed a close relationship between DNA damage rates and apoptotic rates, and the relative coefficient was 0.9021, P<0.01.

CONCLUSION

Selenium at 5-20 micromol/kg can induce DNA damage, apoptosis, and overexpression of c-myc, c-fos, and c-jun in rat hepatocytes.

Immediate-early inducible function in upstream region of junB gene

OBJECTIVE

To analyze the upstream region of radiation-induced junB gene.

METHODS

Four plasmids containing 250 bp, 590 bp, 900 bp and 1650 bp, and CAT reporter gene were constructed separately and introduced to L8704 cells. The cells were irradiated with 2 Gy X-rays and incubated at different intervals. Total RNA was extracted from the cells and fluctuation of the CAT mRNA level was assessed by the RNA ratio of CAT/beta-actin measured by quantitative Northern blot hybridization.

RESULTS

CAT mRNA expression containing 900 bp and 1560 bp junB promoter remarkably and rapidly increased, and reached its peak 30 min after 2 Gy X-ray irradiation.

CONCLUSIONS

590-900 bp fragments located in the upstream region of junB gene play an important role in the early process of cells against radiation.

Edaravone inhibits JNK-c-Jun pathway and restores anti-oxidative defense after ischemia-reperfusion injury in aged rats

Edaravone, a potent antioxidant, is currently being used in the management of acute ischemic stroke in relatively high-aged populations. Mitogen activated protein kinase (MAPK) pathways have been shown to play important roles in neuronal cell death. We examined the role of MAPK pathways and the effect of treatment with edaravone in the brain after cerebral ischemia-reperfusion (I/R) injury in a bilateral carotid artery occlusion (BCAO) model with ischemia for 85 min followed by reperfusion for 45 min in aged rats. Western immunoblotting, immunostaining, enzyme-linked immunosorbent assay (ELISA), spectrophotometry, terminal deoxynucleotidyl transferase nick end labeling (TUNEL) and triphenyl tetrazolium chloride (TTC) staining were performed to evaluate various proteins in the homogenate, c-Jun NH2-terminal kinase (JNK) in the tissue sections, protein carbonyl, glutathione peroxidase (GSHPx), apoptosis and infarct size, respectively. Our results showed that I/R injury resulted in a reduction of GSHPx, but protein carbonyl content and inducible nitric oxide synthase were increased. The activation of JNK and its downstream molecule c-Jun was significantly increased after injury, whereas the activities of p38 MAPK and extracellular-regulated kinase 1/2 were slightly but not significantly increased. Edaravone (3 mg/kg, i.v.) treatment significantly reduced all of these changes. Our findings suggest that the JNK pathway differentially mediates neuronal injury in aged rats after BCAO, and edaravone treatment significantly reduces the neuronal damage after I/R injury by inhibiting oxidative stress and the JNK-c-Jun pathway with concomitant inhibition of overall MAPK activity in the brains of aged rats.

C/EBPalpha directs monocytic commitment of primary myeloid progenitors

C/EBPalpha is required for generation of granulocyte-monocyte progenitors, but the subsequent role of C/EBPalpha in myeloid lineage commitment remains uncertain. We transduced murine marrow cells with C/EBPalpha-estradiol receptor (ER) or empty vector and subjected these to lineage depletion just prior to culture in estradiol with myeloid cytokines. This protocol limits biases due to lineage-specific effects on developmental kinetics, proliferation, and apoptosis. Also, lowering the dose of estradiol reduced activated C/EBPalpha-ER to near the physiologic range. C/EBPalpha-ER increased Mac1(+)/Gr1(-)/MPO(-)/low monocytes 1.9-fold while reducing Mac1(+)/Gr1(+)/MPO(hi) granulocytes 2.5-fold at 48 hours, even in 0.01 microM estradiol. This pattern was confirmed morphologically and by quantitative polymerase chain reaction (PCR) assay of lineage markers. To directly assess effects on immature progenitors, transduced cells were cultured for 1 day with and then in methylcellulose without estradiol. A 2-fold increase in monocytic compared with granulocytic colonies was observed in IL-3/IL-6/SCF or GM-CSF, but not G-CSF, even in 0.01 microM estradiol. C/EBPalpha-ER induced PU.1 mRNA, and PU.1-ER stimulated monocytic development, suggesting that transcriptional induction of PU.1 by C/EBPalpha contributes to monopoiesis. A C/EBPalpha variant incapable of zippering with c-Jun did not induce monopoiesis, and a variant unable to bind NF-kappaB p50 stimulated granulopoiesis, suggesting their cooperation with C/EBPalpha during monocytic commitment.

Role of c-Fos protein on glutamate toxicity in primary neural hippocampal cells

The hippocampus is extremely sensitive to microenvironmental signals and toxic events, including massive glutamate release. Despite the extensive literature related to the cascade of molecular events triggered in postsynaptic neurons, the distinction between proapoptotic and survival pathways is still being discussed. In this study, we have investigated the role of c-Fos in glutamate-induced toxicity in primary cultures of hippocampal neurons by using antisense oligonucleotide (ASO) technology. Exposure of cells (5 days in vitro; DIV) to glutamate 0.5 mM for 24 hr caused massive nuclear alteration. An increase in the number of caspase-3-positive cells was also observed 24 hr after glutamate treatment. The expression of c-fos and c-jun immediate-early genes was increased 30 min after glutamate exposure. The study of c-Fos and c-Jun protein expression revealed an increase in the number of cells positive for both antibodies. To investigate whether the expression of c-Fos protein after glutamate treatment was related to cell death activation or cell survival pathways, cells were exposed to 5 microM of c-fos ASO at 4 DIV, 24 hr before glutamate treatment. The presence of the ASO in the medium significantly decreased the number of altered nuclei, and this was associated with a significant reduction in the number of c-Fos-positive cells after glutamate treatment. Exposure of cells to the c-fos ASO under the conditions described above decreased caspase-3 immunostaining induced by glutamate. These results suggest that the synthesis of c-Fos protein after glutamate exposure favors cell death pathway activation in which caspase-3 is also involved.

Molecular mechanism of cell cycle blockage of hepatoma SK-Hep-1 cells by Epimedin C through suppression of mitogen-activated protein kinase activation and increased expression of CDK inhibitors p21Cip1 and p27Kip1

Reports elsewhere demonstrated that Epimedin C, a constituent isolated from the leaves of Epimedium sagittatum, possessed anti-tumor activity. However, its mechanism of action remains unresolved. Using SK-Hep-1 cells, a poorly-differentiated hepatoma subline, as an experimental model, we present evidence here that the anti-tumor activity of Epimedin C may involve cell cycle blockage. Immunoblotting analyses demonstrated that Epimedin C caused a decreased expression of hyperphosphorylated retinoblastoma (Rb) protein, cyclin D1, c-Myc, and c-Fos. In parallel, we measured the kinase activities and found that CDK2 and CDK4 were suppressed with commensurate increased levels of CDK inhibitors, p21(Cip1) and p27(Kip1). These data suggested that Epimedin C arrested the proliferation of these cells at G0/G1 phase through inhibition of CDK2 and CDK4 activities via an increased induction of p21(Cip1) and p27(Kip1). Alternatively, we investigated whether the anti-proliferative effect of Epimedin C on these cells might involve MAP kinase cascade. Using western blotting technique, we demonstrated that Epimedin C also selectively decreased ERK1/2 phosphorylation. Among the downstream effectors of ERK examined, we found that Epimedin C selectively decreased the expression of c-Fos, but not c-Jun. By EMSA assay, we further demonstrated that decreased c-Fos resulted in the downregulation of AP-1/DNA binding activity. Taken together, the molecular mechanisms of anti-tumor activity of Epimedin C may be proceeded by the combined effects of the cell cycle blockage via either the inhibition of CDK2 and CDK4 activities, with commensurate increase in their inhibitors, p21(Cip1) and p27(Kip1) or negatively modulates the ERK/c-Fos/AP-1 signaling pathway.

Expression of c-jun oncogene in hyperplastic and carcinomatous human prostate

OBJECTIVES

To investigate c-jun oncoprotein (JUN) expression in diseases of the human prostate gland at the tissue level and to determine its relationship to clinicopathologic variables.

METHODS

The expression of JUN was studied using immunohistochemistry in archival tissue from benign prostatic hyperplasia (BPH) (n = 16) and prostate adenocarcinoma (PCa) (n = 36) specimens.

RESULTS

JUN-specific positive nuclear immunostaining was observed in 13 (81.25%) of 16 BPH and 31 (86.1%) of 36 PCa specimens. JUN-specific immunostaining was significantly stronger in the PCa than in the BPH tissue (P = 0.006). In the PCa tissue, no significant correlation was found between JUN immunohistochemical expression and tumor histologic grade (Gleason score) or serum prostate-specific antigen level.

CONCLUSIONS

JUN expression may play a role in normal cell function of the prostatic epithelium and is expressed in most BPH and PCa samples. The finding that JUN-specific immunostaining intensity was stronger in the vast majority of PCa than in the BPH samples implies that the role of c-jun may be enhanced during malignant transformation.

The role of c-Jun in the AP-1 activation induced by naturally occurring isothiocyanates

Despite strong evidence that isothiocyanates (ITCs) inhibit cancer development, there are also reports that some of them induce or promote carcinogenesis. The molecular basis of the latter is largely unknown. We report here that all three ITCs that caused urinary bladder cancer in rats, including allyl ITC, benzyl ITC, and phenethyl ITC, increased the transactivation of activator protein 1 (AP-1) and AP-1 DNA binding in human bladder cancer UM-UC-3 cells. Amongst all Fos and Jun family members examined, only were the levels of c-Jun and Fra-2 consistently elevated by the ITCs. However, whereas c-Jun was identified as the predominant component in the AP-1 DNA binding complex, Fra-2 was not detected, suggesting that c-Jun may be mainly responsible for ITC-induced AP-1 activation. c-Jun was also induced by the ITCs in other bladder cancer cell lines (both human and rat) and by their N-acetylcysteine derivatives--their main urinary metabolites. c-Jun induction by the ITCs appears to involve both transcriptional activation and protein phosphorylation; the latter resulted from activation of c-Jun N-terminal kinase by the ITCs. Because c-Jun has been implicated in cancer development, including human bladder cancer, our data suggest that c-Jun activation may play an important role in ITC-induced bladder carcinogenesis.

Psoriasis-like skin disease and arthritis caused by inducible epidermal deletion of Jun proteins

Psoriasis is a frequent, inflammatory disease of skin and joints with considerable morbidity. Here we report that in psoriatic lesions, epidermal keratinocytes have decreased expression of JunB, a gene localized in the psoriasis susceptibility region PSORS6. Likewise, inducible epidermal deletion of JunB and its functional companion c-Jun in adult mice leads (within two weeks) to a phenotype resembling the histological and molecular hallmarks of psoriasis, including arthritic lesions. In contrast to the skin phenotype, the development of arthritic lesions requires T and B cells and signalling through tumour necrosis factor receptor 1 (TNFR1). Prior to the disease onset, two chemotactic proteins (S100A8 and S100A9) previously mapped to the psoriasis susceptibility region PSORS4, are strongly induced in mutant keratinocytes in vivo and in vitro. We propose that the abrogation of JunB/activator protein 1 (AP-1) in keratinocytes triggers chemokine/cytokine expression, which recruits neutrophils and macrophages to the epidermis thereby contributing to the phenotypic changes observed in psoriasis. Thus, these data support the hypothesis that epidermal alterations are sufficient to initiate both skin lesions and arthritis in psoriasis.

Congenital iodine deficiency and hypothyroidism impair LTP and decrease C-fos and C-jun expression in rat hippocampus

Iodine is essential for the synthesis of triiodothyronine (T(3)) and thyroxine (T(4)). Iodine deficiency leads to inadequate thyroid hormone. Thyroid hormones deficiency during brain development affects cognitive functions, such as attention, learning, and memory. However, the mechanism underlying these deficits is unclear. To investigate the role of iodine deficiency and hypothyroidism in synaptic plasticity, this study examined the induction of long-term synaptic plasticity (LTP) and expression of immediate early (IEA) gene proteins in rat hippocampus following congenital iodine deficiency or hypothyroidism. Through gestation and lactation, iodine-deficient or hypothyroid dam rats were administered with either iodine-deficient diet or methimazole-added drinking water. Exposure was terminated on postnatal day (PN) 30. In hippocampus of pup rats, the induction of LTP in area CA1 was determined on PN60 and the expression of c-fos and c-jun proteins was examined on PN20, PN30 and PN60. Compared to control pups, both treated groups have shown: (1) significantly lower concentrations of serum FT(3) and FT(4), (2) much smaller population spike (PS) amplitude (p<0.01) and field-excitatory postsynaptic potential (f-EPSP) slope induced by high-frequency stimulation (HFS) (P<0.01), and (3) significantly lower integrated optical density (IOD) total of c-fos and c-jun expression (P<0.05 or P<0.01). In summary, iodine deficiency and hypothyroidism during critical periods of brain development impair LTP induction and decrease the expression of c-fos and c-jun proteins in hippocampus.

Interaction of phosphorylated c-Jun with TCF4 regulates intestinal cancer development

The proto-oncoprotein c-Jun is a component of the AP-1 transcription factor, the activity of which is augmented in many tumour types. An important mechanism in the stimulation of AP-1 function is amino-terminal phosphorylation of c-Jun by the c-Jun N-terminal kinases (JNKs). Phosphorylated c-Jun is biologically more active, partially because it acquires the ability to interact with binding partners. Here we show that phosphorylated c-Jun interacts with the HMG-box transcription factor TCF4 to form a ternary complex containing c-Jun, TCF4 and beta-catenin. Chromatin immunoprecipitation assays revealed JNK-dependent c-Jun-TCF4 interaction on the c-jun promoter, and c-Jun and TCF4 cooperatively activated the c-jun promoter in reporter assays in a beta-catenin-dependent manner. In the Apc(Min) mouse model of intestinal cancer, genetic abrogation of c-Jun N-terminal phosphorylation or gut-specific conditional c-jun inactivation reduced tumour number and size and prolonged lifespan. Therefore, the phosphorylation-dependent interaction between c-Jun and TCF4 regulates intestinal tumorigenesis by integrating JNK and APC/beta-catenin, two distinct pathways activated by WNT signalling.

Phosphorylation of histone H3 at serine 10 is indispensable for neoplastic cell transformation

Very little is known about the role of histone H3 phosphorylation in malignant transformation and cancer development. Here, we examine the function of H3 phosphorylation in cell transformation in vivo. Introduction of small interfering RNA-H3 into JB6 cells resulted in decreased epidermal growth factor (EGF)-induced cell transformation. In contrast, wild-type histone H3 (H3 WT)-overexpressing cells markedly stimulated EGF-induced cell transformation, whereas the H3 mutant S10A cells suppressed transformation. When H3 WT was overexpressed, EGF induction of c-fos and c-jun promoter activity was significantly increased compared with control cells but not in the H3 mutant S10A or S28A cells. In addition, activator protein-1 activity in H3 WT-overexpressing cells was markedly up-regulated by EGF in contrast to the H3 mutant S10A or S28A cells. These results indicate that the phosphorylation of histone H3 at Ser10 is an essential regulatory mechanism for EGF-induced neoplastic cell transformation.

Selective regulation of c-jun gene expression by mitogen-activated protein kinases via the 12-o-tetradecanoylphorbol-13-acetate- responsive element and myocyte enhancer factor 2 binding sites

To further understand how the mitogen-activated protein kinase (MAPK) signaling pathways regulate AP-1 activity, we have elucidated the physiological role of these cascades in the regulation of c-jun gene expression. c-Jun is a crucial component of AP-1 complexes and has been shown in vitro to be a point of integration of numerous signals that can differentially affect its expression as well as its transcriptional activity. Our strategy was based on the use of (i) genetically modified fibroblasts deficient in components of the MAPK cascades and (ii) pharmacological reagents. The results demonstrate that c-Jun NH(2)-terminal protein kinase (JNK) is essential for a basal level of c-Jun expression and for c-Jun phosphorylation in response to stress. In addition to JNK, p38 MAPK or ERK1/2 and ERK5 are required for mediating UV radiation- or epidermal growth factor (EGF)-induced c-Jun expression, respectively. Further studies indicate that p38 MAPK inhibits the activation of JNK in response to EGF, causing a down-regulation of c-Jun. Overall, these data provide important insights into the mechanisms that ultimately determine the function of c-Jun as a regulator of cell fate.

Discovery of novel biomarkers by microarray analysis of peripheral blood mononuclear cell gene expression in benzene-exposed workers

Benzene is an industrial chemical and component of gasoline that is an established cause of leukemia. To better understand the risk benzene poses, we examined the effect of benzene exposure on peripheral blood mononuclear cell (PBMC) gene expression in a population of shoe-factory workers with well-characterized occupational exposures using microarrays and real-time polymerase chain reaction (PCR). PBMC RNA was stabilized in the field and analyzed using a comprehensive human array, the U133A/B Affymetrix GeneChip set. A matched analysis of six exposed-control pairs was performed. A combination of robust multiarray analysis and ordering of genes using paired t-statistics, along with bootstrapping to control for a 5% familywise error rate, was used to identify differentially expressed genes in a global analysis. This resulted in a set of 29 known genes being identified that were highly likely to be differentially expressed. We also repeated these analyses on a smaller subset of 508 cytokine probe sets and found that the expression of 19 known cytokine genes was significantly different between the exposed and the control subjects. Six genes were selected for confirmation by real-time PCR, and of these, CXCL16, ZNF331, JUN, and PF4 were the most significantly affected by benzene exposure, a finding that was confirmed in a larger data set from 28 subjects. The altered expression was not caused by changes in the makeup of the PBMC fraction. Thus, microarray analysis along with real-time PCR confirmation reveals that altered expressions of CXCL16, ZNF331, JUN, and PF4 are potential biomarkers of benzene exposure.

Early gene response to low-intensity pulsed ultrasound in rat osteoblastic cells

The aim of the current research was to quantify the changes in gene expression in rat bone marrow derived stromal cells (BMSC) to low intensity pulsed ultrasound (LIPUS) during early time points after the ultrasound application. LIPUS at 1.5 MHz, 30 mW/cm(2) was applied to BMSC for a single 20 min treatment. Real-time PCR was carried out to quantify the expression of early response genes and bone differentiation marker genes 0.5, 1, 3, 6 and 12 h after the end of the LIPUS treatment. Compared with the controls, LIPUS treatment resulted in elevated transient expression of early response genes (c-jun, c-myc, COX-2, Egr-1, TSC-22) as well as the bone differentiation marker genes, osteonectin and osteopontin, at 3 h. This induction of early response genes as well as extracellular matrix genes associated with cell proliferation and differentiation may represent the effect of LIPUS to cells of osteoblastic lineage.

Constitutive expression of the AP-1 transcription factors c-jun, junD, junB, and c-fos and the marginal zone B-cell transcription factor Notch2 in splenic marginal zone lymphoma

Splenic marginal zone lymphoma (SMZL) is a lymphoma type of putative marginal zone B-cell origin. No specific genetic alterations have yet been demonstrated in SMZL. Clinically, SMZL is a low-grade B-cell non-Hodgkin lymphoma. However, the presence of p53 mutation, 7q22-7q32 deletion or the absence of somatic hypermutations of immunoglobulin genes has been correlated with a worse prognosis. In this study, we analyzed genome-wide gene expression of 24 cases of SMZL using the microarray technique. The AP-1 transcription factors c-jun, junD, junB, and c-fos as well as Notch2 were found to be specifically up-regulated. These data were confirmed by real-time PCR and immunohistochemical staining of tissue sections. The absence of concordant high expression of the MAP kinases, the signaling cascade leading to AP-1 up-regulation, suggests autoregulation of the AP-1 transcription factors and an important role in SMZL oncogenesis. High expression of Notch2, a transcription factor that induces marginal zone B-cell differentiation, is highly suggestive for a marginal zone B-cell origin of SMZL. In addition, SMZL with the 7q deletion showed high expression of TGF-beta1 and low expression of the DNA helicase XPB, a crucial part of the nucleotide excision repair complex, possibly explaining the more aggressive clinical course of those cases.

Rice from mercury contaminated areas in Guizhou Province induces c-jun expression in rat brain

OBJECTIVE

Mercury (Hg), as one of the priority pollutants and also a hot topic of frontier environmental research in many countries, has been paid higher attention in the world since the middle of the last century. Guizhou Province (at N24 degrees 30'-29 degrees 13', E103 degrees 1'-109 degrees 30', 1 100 m above the sea level, with subtropical humid climate) in southwest China is an important mercury production center. It has been found that the mercury content in most media of aquatics, soil, atmosphere and in biomass of corns, plants and animals, is higher than the national standard. The present study aims to explore the influence of mercury pollution on the health of local citizens.

METHODS

The effect of rice from two mercury polluted experimental plots of Guizhou Province on the expression of c-jun mRNA in rat brain and c-jun protein in cortex, hippocampus and ependyma was observed using reverse transcription polymerase chain reaction (RT-PCR) and immunocytochemical methods.

RESULTS

The results showed that the mercury polluted rice induced expression of c-jun mRNA and its protein significantly. Selenium can reduce Hg uptake, an antagonism between selenium and mercury on the expression of c-jun mRNA and c-jun protein.

CONCLUSION

c-jun participates in the toxicity process of brain injury by mercury polluted rice, the expression of c-jun mRNA in brain, and c-jun protein in rat cortex and hippocampus can predict neurotoxicity of mercury polluted rice. People should be advised to be cautious in eating any kind of Hg-polluted foods. To reveal the relationship between c-jun induction and apoptosis, further examinations are required.

Differential effects of histone deacetylase inhibitors on phorbol ester- and TGF-β1 induced murine tissue inhibitor of metalloproteinases-1 gene expression

Expression of the tissue inhibitor of metalloproteinases-1 (Timp-1) gene can be induced by either phorbol myristate acetate (PMA) or transforming growth factor beta1 (TGF-beta1), although the signalling pathways involved are not clearly defined. Canonically, histone deacetylase inhibitors (HDACi) such as trichostatin A (TSA) or sodium butyrate (NaB) increase total cellular histone acetylation and activate expression of susceptible genes. Remarkably, PMA and TGF-beta1 stimulation of Timp-1 show a differential response to TSA or NaB. TSA or NaB potentiate PMA-induced Timp-1 expression but repress TGF-beta1-induced Timp-1 expression. The repression of TGF-beta1-induced Timp-1 by TSA was maximal at 5 ng.mL(-1), while for the superinduction of PMA-induced Timp-1 expression, the maximal dose is > 500 ng x mL(-1) TSA. A further HDACi, valproic acid, did not block TGF-beta1-induced Timp-1 expression, demonstrating that different HDACs impact on the induction of Timp-1. For either PMA or TGF-beta1 to induce Timp-1 expression, new protein synthesis is required, and the induction of AP-1 factors closely precedes that of Timp-1. The effects of the HDACi can be reiterated in transient transfection using Timp-1 promoter constructs. Mutation or deletion of the AP-1 motif (-59/-53) in the Timp-1 promoter diminishes PMA-induction of reporter constructs, however, the further addition of TSA still superinduces the reporter. In c-Jun-/- cells, PMA still stimulates Timp-1 expression, but TSA superinduction is lost. Transfection of a series of Timp-1 promoter constructs identified three regions through which TSA superinduces PMA-induced Timp-1 and we have demonstrated specific protein binding to two of these regions which contain either an avian erythroblastosis virus E26 (v-ets) oncogene homologue (Ets) or Sp1 binding motif.

Stress-related gene expression in brain and adrenal gland of porcine fetuses and neonates

This study was conducted to examine stress-induced effects on gene expression of specific markers for HPA axis and neuronal activity in fetuses and neonatal pigs. Brain, pituitary gland, and adrenal gland were obtained to determine the mRNA levels for corticotropin-releasing hormone (CRH), CRH receptor 1 (CRHR1), pro-opiomelanocortin (POMC), ACTH receptor (MC2R), c-jun and c-fos. The suitability of these molecular markers was determined in neonatal pigs which were maternally deprived for two hours. It was found that maternal deprivation caused significantly higher transcript levels of c-fos and CRH in brain accompanied by a down-regulation of CRHR1 mRNA and an up-regulation of c-jun in the pituitary gland. To determine the effect of elevated maternal cortisol levels on gene expression of these molecular markers in fetuses, pregnant sows were treated with 100 IU ACTH (Synacthen Depot) s.c. every two days between Day 49 and Day 75 of gestation (normal gestation length 114 days). Animals were killed 48 hours after the last ACTH administration and fetuses of each sow were isolated. The ACTH treatment of sows significantly increased mRNA expression of c-fos but not of CRH in the fetal brain, and significantly decreased MC2R mRNA expression in the adrenal gland. However, HPA axis seems not to be fully developed in Day 77-fetuses because fetal pituitary CRHR1 and POMC mRNA expression was low in most of the fetuses. Although the expression of endocrine regulatory factors was partially incomplete in fetuses at the beginning of the third-trimester, ACTH dependent activation of c-fos mRNA in brain indicates a stress-related increase of neuronal activity. Based on these results it is assumed that prenatal stress in pigs may also have effects on the activity of the HPA axis in the offspring.