Serotonin-inducible transcription of interleukin-1alpha in uterine smooth muscle cells requires an AP-1 site: cloning and partial characterization of the rat IL-1alpha promoter

Curcumin attenuates carcinogenesis by down regulating proinflammatory cytokine interleukin-1 (IL-1α and IL-1β) via modulation of AP-1 and NF-IL6 in lymphoma bearing mice

Interleukin-1 (IL-1α and IL-1β) is a prototypic, potent, multifunctional proinflammatory cytokine affecting almost all cell types. Expression of IL-1 is up regulated in different tumor phenotypes and is implicated as an important factor in tumor progression via expression of metastatic, angiogenic genes and growth factors. Therefore, down regulation of expression of IL-1 may be able to inhibit cancer progression. Mechanism of transcriptional regulation of mouse IL-1α is not yet reported. AP-1 binding site at -12 to -6 on human IL-1α promotor is highly conserved in rat IL-1α gene and regulates its expression. Based on in silico analysis, regions -12 to -6bp is found to be conserved in human and mouse IL-1α gene promotor and therefore selected to study activation of IL-1α. Further, the regions -12 to -6bp in mouse IL-1α gene promotor corresponding to AP-1 binding element show 3'→5' orientation, necessary for AP-1 binding. The present work is focused on long term effect of curcumin on expression of IL-1α and IL-1β in liver of lymphoma bearing mice. Transcriptional regulation of IL-1α and IL-1β was analyzed by AP-1 and NF-IL-6 respectively. Elevated expression and protein level of IL-1α and IL-1β were found in lymphoma bearing mice compared to normal, which were significantly down regulated by curcumin treatment. Similarly, curcumin treatment down regulated activation of IL-1α and IL-1β via AP-1 and NF-IL-6 respectively. The findings conclude that curcumin attenuates carcinogenesis by down regulating proinflammatory cytokine interleukin-1 (IL-1α and IL-1β) via modulation of AP-1 and NF-IL6 respectively in lymphoma bearing mice.

Peroxisome proliferator-activated receptor-γ ameliorates pulmonary arterial hypertension by inhibiting 5-hydroxytryptamine 2B receptor

An elevated plasma level of 5-hydroxytryptamine (5-HT) or upregulation of 5-HT receptor signaling or both is implicated in vascular contraction and remodeling in pulmonary arterial hypertension (PAH). Recently, peroxisome proliferator-activated receptor-γ (PPARγ) agonists have been shown to ameliorate PAH. However, their effects on the 5-HT-induced contraction of pulmonary arteries remain unknown. Here, we examined the role of PPARγ in inhibiting 5-HT2B receptor (5-HT2BR) to ameliorate PAH. Pulmonary arteries from PAH rats induced by monocrotaline or chronic hypoxia showed an enhanced vasoconstriction in response to BW723C86, a specific agonist for 5-HT2BR. Expression of 5-HT2BR was also increased in pulmonary arteries from the PAH rats, accompanied by vascular remodeling and right ventricular hypertrophy. Treatment with the PPARγ agonist rosiglitazone in vivo reversed the expression and the vasocontractive effect of 5-HT2BR as well as the thickening of pulmonary arteries. In pulmonary artery smooth muscle cells, 5-HT induced the gene expression of 5-HT2BR, which was inhibited by rosiglitazone, pioglitazone, or adenovirus-mediated overexpression of constitutively activated PPARγ. The pharmacological effect of PPARγ was through the suppression of the 5-HT-induced activator protein-1 activity. These results demonstrated the beneficial effect of PPARγ on 5-HT2BR-mediated vasocontraction, providing a new mechanism for the potential use of PPARγ agonists in PAH.

Upregulation of interleukin-1 by Epstein-Barr virus latent membrane protein 1 and its possible role in nasopharyngeal carcinoma cell growth

BACKGROUND

Nasopharyngeal carcinoma (NPC) is associated with Epstein-Barr virus (EBV) infection. We previously found that interleukin (IL)-1alpha and IL-1beta significantly increased in NPC tissues. This study investigated what EBV-encoded proteins were involved in such IL-1 production.

METHODS AND RESULTS

IL-1alpha and IL-1beta messenger ribonucleic acids (mRNAs) were detected in the EBV latent membrane protein 1 (LMP1) transfectant (LMP135) only by reverse transcriptase-polymerase chain reaction (RT-PCR). LMP1-mediated IL-1alpha and IL-1beta production could be enhanced by tumor necrosis factor alpha (TNF-alpha), determined by enzyme-linked immunosorbent assay (ELISA). Moreover, IL-1alpha and IL-1beta mRNAs and proteins were increased in a dose-dependent manner in epithelial cells transiently transfected by an LMP1 plasmid. Besides, immortalized human epidermal keratinocyte (RHEK-1) epithelial cells could be enhanced to proliferate by IL-1alpha and IL-1beta determined by water-soluble tetrazolium salt (WST-1) assay.

CONCLUSIONS

EBV LMP1 is capable of upregulating IL-1alpha and IL-1beta secretions from epithelial cells and positively modulated by TNF-alpha. This may consequently contribute to tumor growth in patients with NPC.

The osterix transcription factor down-regulates interleukin-1 alpha expression in mouse osteosarcoma cells

K7M2 mouse osteosarcoma cells form lytic tumors and are deficient in osterix (Osx), a zinc finger-containing transcription factor required for osteoblast differentiation and bone formation. Our previous studies showed that replacement of Osx suppresses lytic bone destruction. Cytokines, including interleukin (IL)-1alpha, IL-6, IL-11, and prostaglandin E2, have been shown to stimulate osteoclast activity. We showed that IL-1alpha production by K7M2 cells was significantly suppressed following Osx transfection through a transcription-mediated mechanism. Osx had no effect on IL-6, IL-11, or prostaglandin E2. Site-directed mutagenesis and chromatin immunoprecipitation indicated that Osx down-regulated IL-1alpha through an Sp1-binding site on the IL-1alpha promoter. Inhibiting Osx by small interfering RNA in two cell lines (Dunn and DLM8) that expressed high levels of Osx led to enhanced IL-1alpha promoter activity and protein production and altered the phenotype from blastic to lytic. These data suggest that Osx down-regulates IL-1alpha expression in mouse osteosarcoma cells via transcriptional repression of IL-1alpha and this may in turn affect the lytic activity of the tumor cells.

Ischemic tolerance in the brain

Endogenous tolerance to cerebral ischemia is nature's strategy for neuroprotection. Exploring the physiologic and molecular mechanism of this phenomenon may give us new means of protection against ischemia and other degenerative disorders. This article reviews the currently available experimental methods to induce ischemic tolerance in the brain and gives a brief summary of the potential mode of action.

Activation of GATA-4 by serotonin in pulmonary artery smooth muscle cells

Serotonin (5-hydroxytryptamine (5-HT)) is a mitogen of pulmonary artery smooth muscle cells (PASMC) and plays an important role in the development of pulmonary hypertension. Signal transduction initiated by 5-HT involves serotonin transporter-dependent generation of reactive oxygen species and activation of the MEK-ERK pathway. However, the downstream transcriptional regulatory components have not been identified. In systemic smooth muscle cells, GATA-6 has been shown to regulate mitogenesis by driving cells into a quiescent state, and the down-regulation of GATA-6 induces mitogenesis. Thus, the present study tested the hypothesis that 5-HT induces mitogenesis of PASMC by down-regulating GATA-6. Quiescent bovine PASMC were treated with 5-HT, and the binding activity of nuclear extracts toward GATA DNA sequence was monitored. Surprisingly, PASMC express GATA-4, and 5-HT up-regulates the GATA DNA binding activity. Pretreatment of cells with inhibitors of serotonin transporter, reactive oxygen species, and MEK blocks GATA-4 activation by 5-HT. GATA-4 is not activated when the ERK phosphorylation site is mutated, indicating that 5-HT phosphorylates GATA-4 via the MEK/ERK pathway. GATA up-regulation is also induced by other mitogens of PASMC such as endothelin-1 and platelet-derived growth factor. Dominant negative mutants of GATA-4 suppress cyclin D2 expression and cell growth, indicating that GATA-4 activation regulates PASMC proliferation. Thus, GATA-4 mediates 5-HT-induced growth of PASMC and may be an important therapeutic target for the prevention of pulmonary hypertension.

Leishmania major activates IL-1 alpha expression in macrophages through a MyD88-dependent pathway

Leishmania species present unusual challenges to the immune system with their capacity to downregulate inflammatory responses as well as their ability to live within macrophages. Although toll-like receptor (TLR) pathways have been implicated in the recognition of several classes of pro-inflammatory microbes, it is not known if pathogens with anti-inflammatory properties activate the host response through this family of proteins. In this study, Leishmania major stimulation of cytokine promoter-luciferase reporter constructs was examined in transfected macrophages to detect early signs of cellular activation. L. major selectively activated the promoter region of IL-1 alpha, but not IL-6, IL-8, IL-10, or an NF-kappa B reporter. IL-1 alpha mRNA expression was also stimulated by L. major, although at lower levels than lipopolysacharide-stimulated macrophages. No IL-1 alpha protein was detectable in stimulated cell lysates or culture supernatants. Transfection of macrophages with a dominant-negative version of myeloid differentiation factor 88 (MyD88), an adaptor protein which interacts with TLRs, inhibited activation of the IL-1 alpha promoter. Furthermore, stimulation of IL-1 alpha RNA expression by L. major was inhibited in peritoneal macrophages from MyD88-/- as compared to MyD88+/+ mice. These observations indicate that L. major stimulates IL-1 alpha promoter activity and mRNA expression in macrophages through MyD88-dependent pathways. However, additional anti-inflammatory pathways must also be activated which downregulate transcription and ultimately inhibit translation of the IL-1 alpha protein. Examination of promoter activation is a powerful tool for understanding the early events in macrophage activation for anti-inflammatory pathogens such as Leishmania that have mechanisms to downregulate transcription and translation.

Neurotransmitter action in osteoblasts: expression of a functional system for serotonin receptor activation and reuptake

Neurotransmitter regulation of bone metabolism has been the subject of increasing interest and investigation. Because serotonin (5-HT) plays a role as a regulator of craniofacial morphogenesis, we investigated the expression and function of 5-HT receptors and the 5-HT transporter (5-HTT) in bone. Primary cultures of rat osteoblasts (rOB) and a variety of clonal osteoblastic cell lines, including ROS 17/2.8, UMR 106-H5, and Py1a, showed mRNA expression for 5-HTT as well as the 5-HT(1A), 5-HT(1D), 5-HT(2A), and 5-HT(2B) receptors by reverse transcription-polymerase chain reaction (RT-PCR) analysis. Protein expression of the 5-HT(1A), 5-HT(2A), and 5-HT(2B) receptors was confirmed by immunoblot. 5-HTT binding sites were assessed in ROS 17/2.8 and UMR 106-H5 cells by binding of the stable cocaine analog [125I]RTI-55, which showed a relatively high density of nanomolar affinity binding sites. Imipramine and fluoxetine, antagonists with specificity for 5-HTT, showed the highest potency to antagonize [125I]RTI-55 binding in ROS and UMR cells. GBR-12935, a relatively selective dopamine transporter antagonist, had a much lower potency, as did desipramine, a selective norepinephrine transporter antagonist. The maximal [3H]5-HT uptake rate in ROS cells was 110 pmol/10 min per well, with a K(m) value of 1.13 micromol/L. Imipramine and fluoxetine inhibited specific [3H]5-HT uptake with IC(50) values in the nanomolar range. In normal differentiating rOB cultures, 5-HTT functional activity was observed initially at day 25, and activity increased almost eightfold by day 31. In mature rOB cultures, the estimated density of [125I]RTI-55 binding sites was 600 fmol/mg protein. Functional downregulation of transporter activity was assessed after PMA treatment, which caused a significant 40% reduction in the maximal uptake rate of [3H]5-HT, an effect that was prevented by pretreatment with staurosporine. The affinity of 5-HT for the transporter was significantly increased following PMA treatment. We assessed the functional significance of expression of the 5-HT receptors by investigating the interaction between 5-HT and parathyroid hormone (PTH) signaling. 5-HT potentiates the PTH-induced increase in AP-1 activity in UMR cells. These results demonstrate that osteoblastic cells express a functional serotonin system, with mechanisms for responding to and regulating uptake of 5-HT.

Localization and regulation of IL-1alpha in rat myometrium during late pregnancy and the postpartum period

Interleukin-1 (IL-1) has been implicated as a participant in preterm labor that is induced by bacterial infection. Previously, we showed that serotonin-induced production of IL-1alpha by myometrial smooth muscle cells in vitro is also essential for the synthesis of interstitial collagenase. It is therefore likely that IL-1alpha production in uterine tissues has implications for both the normal physiology of involution and for the pathophysiological mechanisms of preterm labor. The objective of this study was to characterize the serotonin-induced production of IL-1alpha by myometrial cultures in vitro and to assess the production of IL-1alpha and its relationship to collagenase production in vivo during pregnancy and the postpartum period. Immunohistochemistry demonstrated IL-1alpha protein in the nuclei and cytoplasm of serotonin-treated myometrial cells. IL-1alpha levels were decreased by treatment with progesterone or IL-1-receptor antagonist but were unaffected by lipopolysaccharide. Western analysis of myometrium from pregnant rats showed low levels of IL-1alpha during midpregnancy with increased concentrations at days 21 and 22 and postpartum. IL-1alpha mRNA levels also increased from days 15 to 22. Levels of mRNA for IL-1beta also increased, although to a lesser degree than IL-1alpha. Both mRNAs decreased postpartum. Conversely, mRNA for interstitial collagenase was barely detectable at term but increased postpartum. Together, these data show that serotonin stimulates IL-1alpha production in vitro and indicate that normal myometrium from pregnant rats is an identifiable source of IL-1 during late pregnancy. The findings are consistent with the possibility that myometrial IL-1alpha participates in normal labor as well as the postpartum production of interstitial collagenase.

CD43-mediated signals induce DNA binding activity of AP-1, NF-AT, and NFkappa B transcription factors in human T lymphocytes

Although numerous reports document a role for CD43 in T cell signaling, the direct participation of this molecule in cell activation has been questioned. In this study we show that CD43 ligation on human normal peripheral T cells was sufficient to induce interleukin-2, CD69, and CD40-L gene expression, without requiring signals provided by additional receptor molecules. This response was partially inhibited by cyclosporin A and staurosporine, suggesting the participation of both the Ca(2+) and the protein kinase C pathways in CD43 signaling. Consistent with the transient CD43-dependent intracellular Ca(2+) peaks reported by others, signals generated through the CD43 molecule resulted in the induction of NF-AT DNA binding activity. CD43-dependent signals resulted also in AP-1 and NFkappaB activation, probably as a result of protein kinase C involvement. AP-1 complexes bound to the AP-1 sequence contained c-Jun, and those bound to the NF-AT-AP-1 composite site contained c-Jun and Fos. NFkappaB complexes containing p65 could be found as early as 1 h after CD43 cross-linking, suggesting that CD43 participates in early events of T cell activation. The induction of the interleukin-2, CD69, and CD-40L genes and the participation of AP-1, NF-AT, and NFkappaB in the CD43-mediated signaling cascade implicate an important role for this molecule in the regulation of gene expression and cell function.

Progesterone mediates decreases in uterine smooth muscle cell interleukin-1alpha by a mechanism involving decreased stability of IL-1alpha mRNA

The regulation, by progesterone, of serotonin-induced interleukin-1alpha production was studied in primary cultures of rat uterine smooth muscle cells. Prior reports from this laboratory have demonstrated that these cells produce IL-1alpha and IL-1beta mRNAs in response to the hormonal action of serotonin. Results of the present study indicate that treatment of myometrial smooth muscle cells with medroxyprogesterone acetate (MPA) results in a marked decrease in IL-1alpha protein as measured by western blot analysis. These decreases occur even in the presence of maximally-inducing concentrations of serotonin. MPA-mediated changes in IL-1alpha protein are characterized by a rapid decline in IL-1alpha mRNA levels. This inhibition by medroxyprogesterone also occurs when cells are stimulated to produce IL-1alpha by PMA rather than serotonin. Thus, when cells are cultured in the presence of both inducer and inhibitor, the inhibitor, progesterone, clearly dominates in the control of IL-1alpha expression. This effect is concentration-dependent, can be mimicked by native progesterone or glucocorticoids, but is unaffected by estradiol. The ability of progestins to decrease IL-1alpha mRNA is blocked by both inhibitors of transcription and translation and by treatment with RU-486. Progesterone had no effect on chloramphenicol acetyl transferase (CAT) transcription from two different IL-1alpha promoter constructs, indicating that progesterone's action appears to be dependent on post-transcriptional rather than transcriptional regulation. Conversely, progesterone accelerated the normal rate of decay of IL-1alpha mRNA that occurs following the removal of serotonin from the cultures. These results suggest that progesterone decreases IL-1alpha levels by stimulating the production of an intracellular intermediate that decreases the stability of IL-1alpha mRNA.