Regulation of interleukin (IL)-11 gene expression in IL-1 induced primate bone marrow stromal cells

Molecular and immunological characterizations of interleukin-11 in large yellow croaker (Larimichthys crocea)

Interleukin (IL)-11 is a multifunctional cytokine that exerts a series of important immunomodulatory effects and exists in many tissues and cells. A 1106-bp nucleotide sequence representing the complete cDNA of IL-11 was obtained from large yellow croaker (Larimichthys crocea), containing an open reading frame (ORF) of 603 bp encoding for 200 amino acids (aa). The predicted LcIL-11 protein included a 12aa signal peptide and a conserved IL-11 domain. The polypeptide sequence identities between LcIL-11 and its counterparts in mammals and other fish are from 84% to 92% with known fish IL-11a and 22%-27% with fish IL-11b. LcIL-11 mRNA existed in most tissues with the most predominant expression in the gill. After immune challenge, the expression levels of LcIL-11 were induced largely in vivo and in vitro, with the peak-value of 32 times as much as the control in the liver at 24 h after Vibrio parahaemolyticus injection (p < 0.05) and the greatest value of 13.9 times as much as the control in LCK cells at 12 h after poly I:C stimulation (p < 0.05). Furthermore, the overexpression vector pcDNA3.1-LcIL-11 was constructed and transfected to LCK cells. Our results showed that the transcriptional expression levels of tumor necrosis factor (TNF)-α and myxovirus resistant protein (Mx) significantly up-regulated in LCK cells after LcIL-11 overexpression (p < 0.05). However, no significant changes of IL-1β, janus kinase (JAK)2 and signal transducers and activators of transcription (STAT)5 was detected. Our finding indicated that LcIL-11 might enhance TNF-α and antiviral protein Mx expression in large yellow croaker.

Expression of the IL-11 Gene in Metastatic Cells Is Supported by Runx2-Smad and Runx2-cJun Complexes Induced by TGFβ1

In tumor cells, two factors are abnormally increased that contribute to metastatic bone disease: Runx2, a transcription factor that promotes expression of metastasis related and osteolytic genes; and IL-11, a secreted osteolytic cytokine. Here, we addressed a compelling question: Does Runx2 regulate IL-11 gene expression? We find a positive correlation between Runx2, IL-11 and TGFβ1, a driver of the vicious cycle of metastatic bone disease, in prostate cancer (PC) cell lines representing early (LNCaP) and late (PC3) stage disease. Further, like Runx2 knockdown, IL-11 knockdown significantly reduced expression of several osteolytic factors. Modulation of Runx2 expression results in corresponding changes in IL-11 expression. The IL-11 gene has Runx2, AP-1 sites and Smad binding elements located on the IL-11 promoter. Here, we demonstrated that Runx2-c-Jun as well as Runx2-Smad complexes upregulate IL-11 expression. Functional studies identified a significant loss of IL-11 expression in PC3 cells in the presence of the Runx2-HTY mutant protein, a mutation that disrupts Runx2-Smad signaling. In response to TGFβ1 and in the presence of Runx2, we observed a 30-fold induction of IL-11 expression, accompanied by increased c-Jun binding to the IL-11 promoter. Immunoprecipitation and in situ co-localization studies demonstrated that Runx2 and c-Jun form nuclear complexes in PC3 cells. Thus, TGFβ1 signaling induces two independent transcriptional pathways - AP-1 and Runx2. These transcriptional activators converge on IL-11 as a result of Runx2-Smad and Runx2-c-Jun interactions to amplify IL-11 gene expression that, together with Runx2, supports the osteolytic pathology of cancer induced bone disease.

PEGylated G-CSF (BBT-015), GM-CSF (BBT-007), and IL-11 (BBT-059) analogs enhance survival and hematopoietic cell recovery in a mouse model of the hematopoietic syndrome of the acute radiation syndrome

Hematopoietic growth factors (HGF) are recommended therapy for high dose radiation exposure, but unfavorable administration schedules requiring early and repeat dosing limit the logistical ease with which they can be used. In this report, using a previously described murine model of H-ARS, survival efficacy and effect on hematopoietic recovery of unique PEGylated HGF were investigated. The PEGylated-HGFs possess longer half-lives and more potent hematopoietic properties than corresponding non-PEGylated-HGFs. C57BL/6 mice underwent single dose lethal irradiation (7.76-8.72 Gy, Cs, 0.62-1.02 Gy min) and were treated with various dosing regimens of 0.1, 0.3, and 1.0 mg kg of analogs of human PEG-G-CSF, murine PEG-GM-CSF, or human PEG-IL-11. Mice were administered one of the HGF analogs at 24-28 h post irradiation, and in some studies, additional doses given every other day (beginning with the 24-28 h dose) for a total of three or nine doses. Thirty-day (30 d) survival was significantly increased with only one dose of 0.3 mg kg of PEG-G-CSF and PEG-IL-11 or three doses of 0.3 mg kg of PEG-GM-CSF (p ≤ 0.006). Enhanced survival correlated with consistently and significantly enhanced WBC, NE, RBC, and PLT recovery for PEG-G- and PEG-GM-CSF, and enhanced RBC and PLT recovery for PEG-IL-11 (p ≤ 0.05). Longer administration schedules or higher doses did not provide a significant additional survival benefit over the shorter, lower dose, schedules. These data demonstrate the efficacy of BBT's PEG-HGF to provide significantly increased survival with fewer injections and lower drug doses, which may have significant economic and logistical value in the aftermath of a radiation event.

Networks controlling mRNA decay in the immune system

The active control of mRNA degradation has emerged as a key regulatory mechanism required for proper gene expression in the immune system. An adenosine/uridine (AU)-rich element (ARE) is at the heart of a first regulatory system that promotes the rapid degradation of a multitude of cytokine and chemokine mRNAs. AREs serve as binding sites for a number of regulatory proteins that either destabilize or stabilize the mRNA. Several kinase pathways regulate the activity of ARE-binding proteins and thereby coordinate the expression of their target mRNAs. Small regulatory micro (mi)-RNAs represent a second system that enhances the degradation of several mRNAs encoding important components of signal transduction cascades that are activated during adaptive and innate immune responses. Specific miRNAs are important for the differentiation of T helper cells, class switch recombination in B cells, and the maturation of dendritic cells. Excitement in this area of research is fueled by the discovery of novel RNA elements and regulatory proteins that exert control over specific mRNAs, as exemplified by an endonuclease that was found to directly cleave interleukin-6 mRNA. Together, these systems make up an extensive regulatory network that controls decay rates of individual mRNAs in a precise manner and thereby orchestrates the dynamic expression of many factors essential for adaptive and innate immune responses. In this review, we provide an overview of relevant factors regulated at the level of mRNA stability, summarize RNA-binding proteins and miRNAs that control their degradation rates, and discuss signaling pathways operating within this regulatory network.

Central nervous system cytokine gene expression: modulation by lead

The environmental heavy metal toxicant, lead (Pb) has been shown to be more harmful to the central nervous system (CNS) of children than to adults, given that Pb exposure affects the neural system during development. Because growth factors and cytokines play very important roles in development of the CNS, we have examined the impact of Pb exposure on the expression of cytokines during CNS development. Cytokine expression was studied in post-natal-day 21 (pnd21) mice by microarray, real-time RT-PCR, Luminex, and ELISA methodologies. BALB/c mouse pups were exposed to Pb through the dam's drinking water (0.1 mM Pb acetate), from gestation-day 8 (gd8) to pnd21. Two cytokines, interleukin-6 (IL-6) and transforming growth factor-β1 (TGF-β1), displayed significantly changed transcript levels in the presence of Pb. IL-6 and TGF-β1 both have signal transduction cascades that can cooperatively turn on the gene for the astrocyte marker glial-fibrillary acidic protein (GFAP). Microarray results indicated that Pb exposure significantly increased expression of GFAP. Pb also modulated IL-6, TGF-β1, and IL-18 protein expression in select brain regions. The deleterious effects of Pb on learning and long-term memory are posited to result from excessive astrocyte growth and/or activation with concomitant interference with neural connections. Differential neural expression of cytokines in brain regions needs to be further investigated to mechanistically associate Pb and neuroinflammation with behavioral and cognitive changes.

Cysteinyl leukotriene upregulates IL-11 expression in allergic airway disease of mice

BACKGROUND

Chronic airway inflammation and airway remodeling are important features of bronchial asthma. IL-11 is one of the important mediators involved in the process of airway inflammation and remodeling. Cysteinyl leukotrienes (cysLTs) play roles in recruitment of inflammatory cells, airway smooth muscle contraction, vascular leakage, increased mucus secretion, decreased mucociliary clearance, and airway fibrosis.

OBJECTIVE

An aim of the present study was to determine the effect of the cysLTs on the regulation of IL-11 expression.

METHODS

We used a C57BL/6 mouse model of allergic airway disease and murine tracheal epithelial cells to examine the effects of cysLTs on the regulation of IL-11 expression.

RESULTS

Our present study with an ovalbumin-induced murine model of allergic airway disease revealed that levels of leukotriene C(4) (LTC(4)) in bronchoalveolar lavage fluids were increased and that administration of montelukast or pranlukast reduced the increased levels of LTC(4); the increased expression of IL-11 protein and mRNA in lung tissues; airway inflammation, bronchial hyperresponsiveness; the increased levels of TGF-beta(1), IL-4, and IL-13 in bronchoalveolar lavage fluids and lung tissues; and airway fibrosis. In addition, LTC(4) stimulates epithelial cells to produce IL-11. Our results also showed that cysLT type 1 receptor antagonists downregulated the activity of a transcription factor, nuclear factor kappaB, and BAY 11-7085 substantially reduced the increased levels of IL-11 after ovalbumin inhalation.

CONCLUSION

These results suggest that cysLTs regulate the IL-11 expression in allergic airway disease.

CLINICAL IMPLICATIONS

These findings provide one of the molecular mechanisms for the effects of cysLTs on airway inflammation and fibrosis in allergic airway diseases.

Interleukin 1 beta is induced by interleukin 11 during decidualization of human endometrial stromal cells, but is not released in a bioactive form

Blastocyst implantation is dependent on the differentiation of endometrial stromal cells (ESC) into decidual cells. Decidualization of human ESC in vitro is enhanced by interleukin 11 (IL11), with associated changes in gene expression. Genes downstream of IL11 may provide targets for the treatment of implantation failure or the development of non-hormonal contraceptives. This study aimed to examine the effect of IL11 on interleukin 1 beta (IL1B) mRNA and protein expression during in vitro decidualization of ESC. Cells were decidualized with 17beta-estradiol and medroxyprogesterone acetate in the presence or absence of exogenous IL11, and IL1B mRNA was quantified by real-time RT-PCR. Inactive proIL1B and bioactive IL1B in cell lysates and conditioned media were measured using specific immunoassays. Secretion of bioactive IL1B from decidualizing ESC was investigated by in vitro stimulation of decidualizing cells with lipopolysaccharide, interferon gamma or human chorionic gonadotropin. Immunohistochemistry was carried out on cycling and pregnant decidua using an antibody specific for bioactive IL1B. Exogenous IL11 increased by 28-fold the abundance of IL1B mRNA in decidualizing ESC, and total immunoreactive IL1B was also increased. However, this was not reflected in bioactive IL1B secretion from these cells, and none of the tested stimuli were able to induce its release. Bioactive IL1B was detected in vivo at very low levels and at discrete foci in late secretory phase and first trimester decidua. This regulation of latent and bioactive IL1B at the fetal-maternal interface may prime decidual cells to respond rapidly to immunological challenge or to signals from the blastocyst during implantation.

Post-transcriptional Control of Cited2 by Transforming Growth Factor β

Cited2 is a transcription factor without typical DNA binding domains. Cited2 interacts with cAMP-responsive element-binding protein-binding protein (CBP)/p300, TFAP2, Lhx2, and nuclear receptors, such as peroxisome proliferator-activated receptor and estrogen receptor to function as a transcriptional modulator. Overexpression of Cited2 in Rat1 cells leads to tumor formation in nude mice, suggesting that Cited2 is a transforming gene. Through microarray analysis, Cited2 was found to be down-regulated by transforming growth factor beta1 (TGF-beta) in various cell lines. In this study, we confirmed that both mRNA and protein levels of Cited2 are down-regulated in MDA-MB-231 breast cancer cells. Overexpression of Smad7 or knockdown of Smad4 in MDA-MB-231 cells showed that the Smad pathway is involved in the down-regulation of Cited2. Based on nuclear run-on analysis and Cited2 promoter/reporter assay, Cited2 transcription was not affected by TGF-beta, supporting that down-regulation of Cited2 by TGF-beta is most likely through post-transcriptional regulation. By using transcriptional inhibitors, we demonstrated that the turnover of Cited2 transcripts appears to be accelerated during TGF-beta stimulation. Pharmacologic inhibition of translation with cycloheximide attenuated Cited2 down-regulation by TGF-beta. We examined the expression of recombinant Cited2 gene introduced into MDA-MB-231 cells by stable transfection, and we found that mRNA containing the Cited2 protein-coding region controlled by a heterologous promoter indeed responds to TGF-beta-mediated down-regulation. Study from Cited2 deletion mutants showed that the C-terminal conserved region of Cited2 coding sequence is essential for the down-regulation. This is the first demonstration that TGF-beta-mediated down-regulation of Cited2 is post-transcriptional, through the Smad pathway, and requires the presence of its coding sequence.

Sp1 family of transcription factors regulates the human alpha2 (XI) collagen gene (COL11A2) in Saos-2 osteoblastic cells

Genes encoding type XI collagen, normally associated with chondrogenesis, are also expressed by osteoblasts. By studying Saos-2 cells, we showed that the transcription factors, Sp1, Sp3, and Sp7 (Osterix), regulate COL11A2 expression through its proximal promoter. The findings indicate both ubiquitous and osteoblast-specific mechanisms of collagen gene regulation.

INTRODUCTION

Type XI collagen is essential for skeletal morphogenesis. Collagen XI gene regulation has been studied in chondrocytes but not in osteoblasts.

MATERIALS AND METHODS

We cultured Saos-2 cells, a human osteosarcoma-derived line of osteoblasts, and analyzed them for alpha2(XI) protein and COL11A2 regulatory mechanisms.

RESULTS AND CONCLUSIONS

Although types I and V were the dominant collagens deposited by Saos-2 cells, they expressed COL11A2 mRNA, and alpha2(XI) chains were present in the extracellular matrix. The COL11A2 promoter region (from -149 to -40) containing three Sp1 binding sites was required for promoter activity in transient transfection assays. All three Sp1 sites were critical for binding by nuclear proteins in electrophoretic mobility shift assays. Further analysis using consensus oligonucleotides and specific antibodies as well as chromatin immunoprecipitation assay implicated Sp1 and Sp3 in binding to this promoter region. Overexpressing Sp1 or Sp3 significantly increased COL11A2 promoter activity and endogenous COL11A2 gene expression, an effect that was suppressed by the Sp1-binding inhibitor mithramycin A. Further experiments showed that Sp1, Sp3, CREB-binding protein (CBP), p300, and histone deacetylase (HDAC) were physically associated and HDAC inhibitors (trichostatin A or NaB) upregulated COL11A2 promoter activity and endogenous gene expression. Another Sp1 family member, Sp7 (Osterix), was expressed in Saos-2 cells, but not in chondrocytes, and was shown by chromatin immunoprecipitation to occupy the COL11A2 promoter. Overexpressing Sp7 increased COL11A2 promoter activity and endogenous gene expression, an effect also blocked by mithramycin A. Using siRNA to knockdown Sp1, Sp3, or Sp7, it was shown that depression of any of them decreased COL11A2 promoter activity and endogenous gene expression. Finally, primary cultures of osteoblasts expressed COL11A2 and Sp7, upregulated COL11A2 promoter activity and endogenous gene expression when Sp1, Sp3, or Sp7 were overexpressed, and downregulated them when Sp1, Sp3, or Sp7 were selectively depressed. The results establish that Sp1 proteins regulate COL11A2 transcription by binding to its proximal promoter and directly interacting with CBP, p300, and HDAC.

Posttranscriptional mechanisms regulating the inflammatory response

The inflammatory response is a complex physiologic process that requires the coordinate induction of cytokines, chemokines, angiogenic factors, effector-enzymes, and proteases. Although transcriptional activation is required to turn on the inflammatory response, recent studies have revealed that posttranscriptional mechanisms play an important role by determining the rate at which mRNAs encoding inflammatory effector proteins are translated and degraded. Most posttranscriptional control mechanisms function to dampen the expression of pro-inflammatory proteins to ensure that potentially injurious proteins are not overexpressed during an inflammatory response. Here we discuss the factors that regulate the stability and translation of mRNAs encoding pro-inflammatory proteins.

Cloning and expression of the first nonmammalian interleukin-11 gene in rainbow trout Oncorhynchus mykiss

Interleukin (IL)-11 is a multifunctional cytokine that stimulates hematopoietic progenitor cells and exerts a series of important immunomodulatory effects. It was believed to be restricted to mammals, but here we report the first nonmammalian IL-11 gene, in rainbow trout (Oncorhynchus mykiss). A trout IL-11 cDNA clone was isolated that contains a 5'-untranslated region (UTR) of 400 bp, an open reading frame of 612 bp and a large 3'-UTR of 1924 bp. Analysis of a genomic DNA clone from a trout lambda library revealed that the trout IL-11 gene has the same five exon/four intron gene organization, as well as the same intron phase, as mammalian IL-11 genes. The 204 amino acid trout IL-11 translation has a predicted signal peptide of 26 amino acids and mature peptide of 178 amino acids, with a calculated molecular mass of 20.5 kDa and a theoretical pI of 9.83. The mature peptide contains a cysteine residue and a potential N-linked glycosylation site that are not present in mammals. Phylogenetic analysis clearly grouped trout IL-11 with IL-11 molecules from other species and separated from other members of the IL-6 family. The IL-11 gene is highly expressed in intestine and gills in healthy fish and its expression can also be detected in spleen, head kidney, brain, skin and muscle. Bacterial infection of rainbow trout markedly up-regulates IL-11 expression in liver, head kidney and spleen. IL-11 expression is also up-regulated in RTS-11 cells (a trout macrophage cell line), which constitutively expressed the lowest level of IL-11 of the four trout cell lines examined, after stimulation with bacteria, lipopolysaccharide, poly(I:C) and recombinant trout IL-1beta. Only a single transcript of 3.2 kb could be detected in lipopolysaccharide or recombinant IL-1beta-stimulated RNA samples by northern blotting. The expression results, showing that IL-11 is widely distributed and modulated by infection and other cytokines, suggest that fish IL-11 is an active player in the cytokine network and the host immune response to infection.

Hepatocyte growth factor plays roles in the induction and autocrine maintenance of bone marrow stromal cell IL-11, SDF-1 alpha, and stem cell factor

OBJECTIVE

Bone marrow (BM) stroma provides the microenvironment required for long-term hematopoiesis, and this is supported by direct interaction between stromal cells and hematopoietic cells, mediated by adhesion molecules, and through cytokine releases from the BM stroma. In a previous study, we demonstrated that hepatocyte growth factor (HGF) is one of the cytokines constitutively produced from BM stromal cells, promoting hematopoiesis mainly in an indirect way. We also showed that stromal cells themselves express HGF receptor c-MET. It was therefore postulated that HGF exerts its effect on hematopoiesis and maintenance of the hematopoietic microenvironment in a paracrine and autocrine manner.

METHODS

The effect of HGF on stromal cells was analyzed by neutralizing intrinsic HGF.

RESULTS

Addition of neutralizing anti-HGF antibody inhibited the ability of BM stromal cells to support colony formation from CD34(+) cells and reduced production of significant cytokines from stromal cells, interleukin-11 (IL-11), stromal cell-derived factor-1 alpha (SDF-1 alpha), and to a lesser extent, stem cell factor (SCF). Furthermore, this neutralizing antibody reduced proliferation of stromal cells and inhibited adhesion of stromal cells to collagen type IV and fibronectin. Inhibition of adhesion to fibronectin was mediated by inhibition of alpha(5)beta(1)-integrin.

CONCLUSION

These findings indicate that HGF constitutively produced from BM stromal cells is an autocrine regulator, which is able to maintain the hematopoietic microenvironment through stimulating proliferation and adhesion to the extracellular matrix and promoting hematopoiesis through inducing constitutive production of IL-11, SDF-1 alpha, and SCF by stromal cells themselves.

Inhibitors of p38 mitogen-activated protein kinase: potential as anti-inflammatory agents in asthma?

Asthma is an inflammatory disease of the airways, which in patients with mild to moderate symptoms is adequately controlled by either beta(2)-adrenoceptor agonists or corticosteroids, or a combination of both. Despite this, there are classes of patients that fail to respond to these treatments. In addition, there is a general trend towards increasing morbidity and mortality due to asthma, which suggests that there is a need for new and improved treatments. The p38 mitogen-activated protein kinases (MAPKs) represent a point of convergence for multiple signalling processes that are activated in inflammation and that impact on a diverse range of events that are important in inflammation. Small molecule pyridinyl imidazole inhibitors of p38 MAPK have proved to be highly effective in reducing various parameters of inflammation, in particular cytokine expression. Like corticosteroids, inhibitors of p38 MAPK appear to be able to repress gene expression at multiple levels, for example, by transcriptional, posttranscriptional and translational repression, and this raises the possibility of a similarly broad spectrum of anti-inflammatory activities. Indeed these molecules have proved to be effective in numerous in vitro and in vivo models of inflammation and septicaemia, which suggests that such compounds may be effective as therapeutic agents against inflammatory disorders. Despite these very promising indications of the possible therapeutic use of p38 MAPK inhibitors, a number of events that are p38-dependent are in fact also beneficial to the resolution or modulation of diseases such as asthma. We conclude that the overall effect of p38 MAPK inhibition would be beneficial in inflammatory diseases such as rheumatoid arthritis and asthma. However, these drugs may result in a complex phenotype that will require careful evaluation. Currently, a number of second or third generation inhibitors of p38 MAPK are being tested in phase I and phase II clinical trials.

Regulation of IL-11 expression in intestinal myofibroblasts: role of c-Jun AP-1- and MAPK-dependent pathways

IL-11 inhibits the activation of NF-kappaB and induces the Th2 polarization of CD4+ T cells. The clinical utility of IL-11 is being investigated in Crohn's disease. However, physiological secretion of IL-11 in the intestine remains unclear. In this study, we investigated IL-11 secretion in human intestinal subepithelial myofibroblasts (SEMFs). Intestinal SEMFs were isolated from the human colonic mucosa. IL-11 secretion and mRNA expression were determined by ELISA and Northern blot analysis. The activating protein (AP)-1-DNA binding activity was evaluated by EMSA. IL-11 secretion was induced by IL-1beta and transforming growth factor (TGF)-beta1. These were also observed at the mRNA level. The EMSAs demonstrated that both IL-1beta and TGF-beta1 induced AP-1 activation within 2 h after stimulation, and a blockade of AP-1 activation by the recombinant adenovirus containing a dominant negative c-Jun markedly reduced the IL-1beta- and TGF-beta1-induced IL-11 mRNA expression. IL-1beta and TGF-beta1 induced an activation of ERK p42/44 and p38 MAP kinases, and the MAP kinase inhibitors (SB-202190, PD-98059, and U-0216) significantly reduced the IL-1beta- and TGF-beta1-induced IL-11 secretion. The upregulation of IL-11 mRNA by IL-1beta- and TGF-beta1 was also mediated by a p38 MAP kinase-mediated mRNA stabilization. The combination of IL-1beta and TGF-beta1 additively enhanced IL-11 secretion. Intestinal SEMFs secreted IL-11 in response to IL-1beta- and TGF-beta1. Mucosal IL-11 secretion might be important as an anti-inflammatory response in the pathogenesis of intestinal inflammation.

COL11A2 collagen gene transcription is differentially regulated by EWS/ERG sarcoma fusion protein and wild-type ERG

A specific t(21;22) chromosomal translocation creates the chimeric EWS/ERG gene in some cases of Ewing's sarcoma. In the resultant EWS/ERG fusion protein, the N-terminal part of the ETS family protein ERG is replaced by the N terminus of the RNA-binding protein EWS. We found that both the EWS/ERG and COL11A2 genes are expressed in the Ewing's sarcoma cell line, CADO-ES1. To investigate a potential role for EWS/ERG in COL11A2 gene expression, we characterized the COL11A2 promoter and tested the ability of wild-type ERG and EWS/ERG sarcoma fusion protein to transactivate COL11A2 promoter using a luciferase assay. We found that expression of EWS/ERG, but not wild-type ERG, transactivated the COL11A2 promoter and that this transactivation required not only the N-terminal region of EWS but also an intact DNA-binding domain from ERG. Electrophoretic mobility shift assay using COL11A2 promoter sequence showed involvement of EWS/ERG in the formation of DNA-protein complexes, and chromatin immunoprecipitation assay revealed direct interaction between COL11A2 promoter and EWS/ERG fusion protein in vivo. EWS/ERG, but not wild-type ERG, bound to RNA polymerase II. Treatment of cells with the histone deacetylase inhibitor trichostatin A enabled ERG to transactivate the COL11A2 promoter, therefore abolishing the differential effects of EWS/ERG and ERG. Taken together, these findings indicate that the COL11A2 gene is regulated both by potential ERG association with a histone deacetylase complex and by direct EWS/ERG recruitment of RNA polymerase II.

Leustroducsin B activates nuclear factor-kappaB via the acidic sphingomyelinase pathway in human bone marrow-derived stromal cell line KM-102

The novel colony-stimulating factor (CSF) inducer leustroducsin B (LSN-B), which was isolated from Streptomyces platensis, has been shown to have potent cytokine-inducing activities in clonal human bone marrow-derived stromal cell line KM-102 and in primary human bone marrow-derived stromal cells. In this study, we investigated the signal transduction pathway of LSN-B using luciferase expression plasmids linked to the 5'-flanking region of interleukin-8 (IL-8) and that of the IL-11 gene. In KM-102 cells, LSN-B induced luciferase activity both in the wild-type and in the activated protein 1 (AP-1) site point-mutated IL-8 promoter. The mutation in the nuclear factor-kappaB (NF-kappaB) site abrogated LSN-B-stimulated induction of the reporter gene. LSN-B-inducing activity was inhibited by (1) N-acetyl-L-cysteine, a well-characterized antioxidant, (2) cationic amphiphilic drugs, inhibitors of acidic sphingomyelinase (A-SMase), and (3) D609, an inhibitor of phosphatidylcholine-specific phospholipase C (PC-PLC). These observations suggest that LSN-B potentiates the A-SMase-mediated signaling pathway to stimulate NF-kappaB. In contrast, LSN-B did not induce IL-11 promoter-driven luciferase activity. The observed increase in IL-11 mRNA stability by LSN-B indicates that the inducible production of IL-11 by LSN-B is regulated at the posttranscriptional level. In addition, inhibition of LSN-B-mediated induction of IL-11 production by cationic amphiphilic drugs and D609 in KM-102 cells demonstrates that increased IL-11 mRNA stability by LSN-B might be mediated via NF-kappaB activation. From these results, we suggest that LSN-B induces cytokine production through at least two separate mechanisms, at the transcriptional level and at the posttranscriptional level via NF-kappaB activation.

Posttranscriptional regulation of cyclooxygenase-2 in rat intestinal epithelial cells

Modulation of cyclooxygenase-2 (COX-2) mRNA stability plays an important role in the regulation of its expression by oncogenic Ras. Here, we evaluate COX-2 mRNA stability in response to treatment with two known endogenous promoters of gastrointestinal cancer, the bile acid (chenodeoxycholate; CD) and ceramide. Treatment with CD and ceramide resulted in a 10-fold increase in the level of COX-2 protein and a four-fold lengthening of the half-life of COX-2 mRNA. COX-2 mRNA stability was assessed by Northern blot analysis and by evaluating the AU-rich element located in the COX-2 3'-UTR. A known inhibitor of mitogen-activated protein (MAP)/extracellular signal-regulated kinase (ERK) kinase (MEK), PD98059, reversed the effects of CD or ceramide to stabilize COX-2 mRNA. Overexpression of a dominant-negative ERK-1 or ERK-2 protein also led to destabilization of COX-2 mRNA. Treatment with a p38 MAPK inhibitor, PD169316, or transfection with a dominant-negative p38 MAPK construct reversed the effect of CD or ceramide to stabilize COX-2 mRNA. Expression of a dominant-negative c-Jun N-terminal kinase (JNK) had no effect on COX-2 mRNA stability in cells treated with CD or ceramide. We conclude that posttranscriptional mechanisms play an important role in the regulation of COX-2 expression during carcinogenesis.

gp130 Cytokine family and bone cells

Bone tissue is continually being remodelled according to physiological circumstances. Two main cell populations (osteoblasts and osteoclasts) are involved in this process, and cellular activities (including cell differentiation) are modulated by hormones, cytokines and growth factors. Within the last 20 years, many factors involved in bone tissue metabolism have been found to be closely related to the inflammatory process. More recently, a cytokine family sharing a common signal transducer (gp130) had been identified, which appears to be a key factor in bone remodelling. This family includes interleukin 6, interleukin 11, oncostatin M, leukaemia inhibitory factor, ciliary neurotrophic factor and cardiotrophin-1. This paper provides an exhaustive review of recent knowledge on the involvement of gp130 cytokine family in bone cell (osteoblast, osteoclast, etc.) differentiation/activation and in osteoarticular pathologies.

Interleukin-1-mediated stabilization of mouse KC mRNA depends on sequences in both 5'- and 3'-untranslated regions

mRNA transcribed from the mouse KC chemokine gene accumulated to significantly higher levels in multiple cell types after treatment with interleukin 1alpha (IL-1alpha) as compared with tumor necrosis factor-alpha (TNFalpha). Although TNFalpha and IL-1alpha both signaled the activation of nuclear factor kappaB and enhanced transcription of the KC gene with equal potency, only IL-1alpha treatment resulted in stabilization of KC mRNA. Nucleotide sequences that confer sensitivity for IL-1alpha-mediated mRNA stabilization were identified within the 5'- and 3'-untranslated regions (UTRs) of KC mRNA using transient transfection of chimeric plasmids containing specific portions of KC mRNA linked to the chloramphenicol acetyltransferase (CAT) gene. When plasmids containing either the 3'- or 5'-UTR of KC mRNA were used, the half-life of CAT mRNA was unaltered either in untreated or IL-1alpha-stimulated cells. In contrast, CAT mRNA transcribed from plasmids that contained both the 5'- and 3'-UTRs of the KC mRNA decayed more rapidly than control CAT mRNA, and this enhanced decay was prevented in cells treated with IL-1alpha. A cluster of four overlapping AUUUA motifs within the 3'-UTR was required, whereas the 5'-UTR region exhibited orientation dependence. These findings indicate that cooperative function of the two nucleotide sequences involves a distinct signaling pathway used by IL-1alpha but not TNFalpha.

Role of the endogenous prostaglandin E2 in human lung fibroblast interleukin-11 production

Interleukin-11 (IL-11) is known to be a member of the interleukin-6 (IL-6)-type cytokine family. IL-11 is likely to be a major determinant of immune regulation in acute and chronic inflammatory lung diseases, although it is not directly linked with specific disease processes. It has already been shown that although unstimulated human lung fibroblasts did not produce significant amounts of IL-11, the addition of interleukin-1 alpha (IL-1 alpha) and/or transforming growth factor-beta (TGF-beta) stimulated fibroblasts dose-dependently to produce IL-11. Northern blot analysis showed that these stimulators also upregulated IL-11 mRNA expression. As it has been previously reported that IL-1 and TGF-beta stimulate prostaglandin E2 (PGE2) release from lung fibroblasts, we investigate here the role of endogenous PGE2 and the direct effects of the two inhibitors of prostaglandin synthesis, indomethacin and dexamethasone, on IL-11 production by human lung fibroblasts. The addition of indomethacin, a cyclo-oxygenase inhibitor, resulted in significant suppression of IL-11 production and mRNA expression in lung fibroblasts. There was no detectable effect of PGE2 alone on IL-11 levels; however, the suppression of IL-11 production by indomethacin was almost completely reversed by addition of PGE2. In contrast, suppression of IL-11 production by indomenthacin was not reversed by addition of thromboxane B2 and carbocyclic thromboxane A2. In addition, dexamethasone completely suppressed IL-11 production and downregulated IL-11 mRNA. These results suggest that endogenous PGE2 acts as an autocrine stimulus for IL-11 production by human lung fibroblasts activated by IL-1 alpha and TGF-beta.

Modulation of tumor necrosis factor and interleukin-1-dependent NF-kappaB activity by mPLK/IRAK

The innate immune response is an important defense against pathogenic agents. A component of this response is the NF-kappaB-dependent activation of genes encoding inflammatory cytokines such as interleukin-8 (IL-8) and cell adhesion molecules like E-selectin. Members of the serine/threonine innate immune kinase family of proteins have been proposed to mediate the innate immune response. One serine/threonine innate immune kinase family member, the mouse Pelle-like kinase/human interleukin-1 receptor-associated kinase (mPLK/IRAK), has been proposed to play an obligate role in promoting IL-1-mediated inflammation. However, it is currently unknown whether mPLK/IRAK catalytic activity is required for IL-1-dependent NF-kappaB activation. The present study demonstrates that mPLK/IRAK catalytic activity is not required for IL-1-mediated activation of an NF-kappaB-dependent signal. Intriguingly, catalytically inactive mPLK/IRAK inhibits type 1 tumor necrosis factor (TNF) receptor-dependent NF-kappaB activation. The pathway through which mPLK/IRAK mediates this TNF response is TRADD- and TRAF2-independent. Our data suggest that in addition to its role in IL-1 signaling, mPLK/IRAK is a component of a novel signal transduction pathway through which TNF R1 activates NF-kappaB-dependent gene expression.

Repression of cyclooxygenase-2 and prostaglandin E2 release by dexamethasone occurs by transcriptional and post-transcriptional mechanisms involving loss of polyadenylated mRNA

The two cyclooxygenase (COX) isoforms convert arachidonic acid to precursor prostaglandins (PGs). Up-regulation of COX-2 is responsible for increased PG production in inflammation and is antagonized by corticosteriods such as dexamethasone. In human pulmonary A549 cells, interleukin-1beta (IL-1beta) increases prostaglandin E2 (PGE2) synthesis via dexamethasone-sensitive induction of COX-2. Nuclear run-off assays showed that COX-2 transcription rate was repressed 25-40% by dexamethasone, while PGE2 release, COX activity, and COX-2 protein were totally repressed. At the mRNA level, complete repression of COX-2 was only observed at later (6 h) time points. Preinduced COX-2 mRNA was also potently repressed by dexamethasone, yet suppression of transcription by actinomycin D showed little effect. This dexamethasone-dependent repression involved a reduced COX-2 mRNA half-life, was blocked by actinomycin D or cycloheximide, and was antagonized by the steroid antagonist RU38486. Repression of IL-1beta-induced PGE2 release, COX activity, and COX-2 protein by actinomycin D was only effective within the first hour following IL-1beta treatment, while dexamethasone was effective when added up to 10 h later, suggesting a functional role for post-transcriptional mechanisms of repression. Following dexamethasone treatment, shortening of the average length of COX-2 mRNA poly(A) tails was observed. Finally, ligation of the COX-2 3'-UTR to a heterologous reporter failed to confer dexamethasone sensitivity. In conclusion, these data indicate a major role for post-transcriptional mechanisms in the dexamethasone-dependent repression of COX-2 that require de novo glucocorticoid receptor-dependent transcription and translation. This mechanism involves shortening of the COX-2 poly(A) tail and requires determinants other than just the 3'-UTR for specificity.

Differential inhibitory effects of indomethacin, dexamethasone, and interferon-gamma (IFN-gamma) on IL-11 production by rheumatoid synovial cells

IL-11, a member of the IL-6 type cytokines, has some biological activity related to the joint destruction in rheumatoid arthritis (RA), such as induction of osteoclast differentiation. However, its expression and regulation in rheumatoid inflamed joints has not been clarified. In the present study we examined the capacity of fresh rheumatoid synovial cells (fresh RSC) to produce IL-11, and the effect of indomethacin, dexamethasone and IFN-gamma on IL-11 production. Fresh RSC obtained from eight patients with RA produced large amounts of IL-11, measured by ELISA, and showed strong expression of IL-11 mRNA, determined by Northern blotting. Indomethacin inhibited the production of IL-11 by about 55%. Prostaglandin E2 (PGE2) completely prevented the inhibition, suggesting that IL-11 production by fresh RSC was in part mediated by PGE2. Dexamethasone inhibited the production of IL-11 by more than 80%. Interestingly, the inhibition was not abolished by PGE2. IFN-gamma inhibited the production of IL-11 from IL-1alpha-stimulated cultured rheumatoid synovial fibroblasts, although IFN-gamma did not inhibit the production of IL-11 by fresh RSC. These results suggest that the production of IL-11 by rheumatoid synovia was differentially regulated by PGE2 and IFN-gamma, and that treatment with indomethacin or dexamethasone decreased the level of IL-11 at inflammatory joints in patients with RA.

Transforming growth factor-beta stimulates interleukin-11 transcription via complex activating protein-1-dependent pathways

Studies were undertaken to characterize the mechanism by which transforming growth factor-beta1 (TGF-beta1) stimulates epithelial cell interleukin (IL)-11 production. Nuclear run-on studies demonstrated that TGF-beta1 is a potent stimulator of IL-11 gene transcription. TGF-beta1 also stimulated the luciferase activity in cells transfected with reporter gene constructs containing nucleotides -728 to +58 of the IL-11 promoter. Studies with progressive 5' deletion constructs and site-specific mutations demonstrated that this stimulation was dependent on 2 AP-1 sites between nucleotides -100 and -82 in the IL-11 promoter. Mobility shift assays demonstrated that TGF-beta1 stimulated AP-1 protein-DNA binding to both AP-1 sites. Supershift analysis demonstrated that JunD was the major moiety contributing to AP-1-DNA binding in unstimulated cells and that c-Jun-, Fra-1-, and Fra-2-DNA binding were increased whereas JunD-DNA binding was decreased in TGF-beta1-stimulated cells. The sequence in the IL-11 promoter that contains the AP-1 sites also conferred TGF-beta1 responsiveness, in a position-independent fashion, on a heterologous minimal promoter. Thus, TGF-beta1 stimulates IL-11 gene transcription via a complex AP-1-dependent pathway that is dependent on 2 AP-1 motifs between nucleotides -100 and -82 that function as an enhancer in the IL-11 promoter.

Transcriptional induction of multiple cytokines by human respiratory syncytial virus requires activation of NF-kappa B and is inhibited by sodium salicylate and aspirin

Infection of the lung epithelial cell line A549 by respiratory syncytial virus (RSV) resulted in the elevated synthesis of multiple cellular cytokines, including a number of interleukins (ILs). Detailed studies of IL-11 induction revealed that it required infection by viable virus and involved a net increase in the steady state level of IL-11 mRNA. Nuclear run-on assays showed a direct effect of RSV on IL-11 gene transcription. Mutational analysis of the IL-11 promoter fused to a reporter luciferase gene demonstrated the requirement of a region 720 nucleotides upstream of the mRNA start site in the transcriptional induction of IL-11 by RSV. Two nearly identical 10-nucleotide-long sequences GGGGTCTCCC and GGGTCTCCCC in this region resembled the NF-kappa B consensus motif. Mutation of either sequence greatly reduced RSV-mediated induction of IL-11 promoter activity. NF-kappa B sites in IL-1 alpha, IL-6, and IL-8 promoters were also required for RSV-mediated induction of transcription of these promoters. Immunological studies and use of reporter gene constructs provided direct evidence for the activation and nuclear translocation of NF-kappa B by RSV. Sodium salicylate and aspirin, inhibitors of NF-kappa B activation, abolished transcriptional induction of all these cytokines by RSV. Together, these studies demonstrated an essential role of NF-kappa B in RSV-mediated transcription of multiple cytokines genes and suggested a possible use of salicylates in managing airway inflammation and viral pathogenesis during RSV infection.

Alternate COX-2 transcripts are differentially regulated: implications for post-transcriptional control

Prostaglandin (PG) synthesis during inflammation occurs mainly via the transcriptionally regulated cyclooxygenase, COX-2. In pulmonary type II A549 cells, Northern analysis identified multiple IL-1 beta-inducible COX-2 mRNA transcripts. Amplification of 3'-cDNA ends by anchored PCR revealed products corresponding to the predominant 4.5 and 2.7 kb transcripts. Sequence analysis of amplification products indicated that these transcripts arose by alternate consensus and non-consensus polyadenylation site usage. The predominant 4.5 kb transcript showed a half-life in excess of two hours that was further stabilized by IL-1 beta. In addition, the COX-2 3'-untranslated region (UTR), which contains 22 copies of the putative RNA instability motif, AUUUA, when cloned downstream of a constitutively expressed luciferase gene, was found to confer partial IL-1 beta responsiveness in LA-4 cells. Finally, in vivo in LPS-treated rats, differential expression of similar COX-2 mRNA isoforms was also observed. Taken together these data suggest a functional role for post-transcriptional mechanisms, including alternate polyadenylation, in the control of COX-2.

Influence of interferon-alpha on cytokine expression by the bone marrow microenvironment--impact on treatment of myeloproliferative disorders

Myeloproliferative disorders (MPD) are characterized by several common clinical and biological features, although at the molecular level, each disease entity exhibits distinct abnormalities. IFN-alpha exerts beneficial therapeutic effects in chronic myelogenous leukemia, polycythemia vera and essential thrombocythemia, resulting in control of hematopoietic hyperplasia and, in a minority of patients, in induction of cytogenetic remission. The mechanism of action of IFN-alpha in MPD is poorly defined. Recently published in vitro findings suggest that IFN-alpha interacts with the regulation of hematopoiesis by multiple ways. Its antiproliferative activity is well known for more than a decade, however, substantial growth inhibition is achieved only at relatively high concentrations. Defective adhesion of hematopoietic progenitor cells in CML to bone marrow stromal cells is corrected by IFN-alpha, which might expose CML progenitors to inhibitory cytokines produced by the bone marrow microenvironment. Recent work from our group demonstrated, that IFN-alpha potently interacts with the production of hematopoietic cytokines in bone marrow stromal cells. Expression of stimulatory cytokines, such as GM-CSF, G-CSF, IL-1 and IL-11 is inhibited by IFN-ct, whereas the production of negative regulators, such as IL-1RA and MIP-1 alpha, is stimulated. The combined action of IFN-alpha on paracrine expression of cytokines suggests an indirect antihematopoietic effect, which might contribute to its clinical activity in MPD.

Interferon-alpha and its effects on the cytokine cascade: a pro- and anti-inflammatory cytokine

Interferon-alpha (IFN alpha) has emerged as an important regulator of growth and differentiation, affecting cellular communication and signal transduction pathways as well as immunological control. The efficacy of IFN alpha has been demonstrated in many different diseases of viral, malignant, angiogenic, allergic, inflammatory, and fibrotic origin. Cytokines are pleiotropic and redundant molecules showing a wide variety of biologic functions on various tissues and cells, and several different cytokines exert similar and overlapping functions on certain cells. Data gained in the last years support this view also for IFN alpha. Initially thought to have mainly immunomodulating and proinflammatory effects, recent data suggest that IFN alpha has several anti-inflammatory properties. These newly identified anti-inflammatory and immunosuppressive functions may help to explain some of the IFN mechanisms.

Differential regulation of the stability of cytokine mRNAs in lipopolysaccharide-activated blood monocytes in response to interleukin-10

Adenosine-uridine (AU) instability elements, found in the 3'-untranslated regions of numerous mRNAs, target these mRNAs for rapid degradation. In addition, the degradation rate of some mRNAs that contain AU instability elements can change. This modulation of mRNA stability is an important component in the regulation of expression of many of the cytokines that control the production and function of blood cells. However, it has not been clear whether the stabilities of individual cytokine mRNAs that contain AU instability elements are coordinately regulated or whether different mRNAs can be independently regulated. We have investigated the influence of the cytokine synthesis inhibitory factor interleukin (IL)-10 on the turnover of granulocyte-colony stimulating factor (G-CSF), granulocyte macrophage-colony stimulating factor (GM-CSF), and IL-10 mRNAs in human blood monocytes stimulated with lipopolysaccharide. We find that all three mRNAs are destabilized in response to IL-10 but at different times. The G-CSF and GM-CSF mRNAs respond similarly, being rapidly destabilized, consistent with a direct influence of IL-10 receptor-mediated signals on the stability of these mRNAs. In contrast the IL-10 mRNA became unstable only after several hours of treatment with IL-10, suggesting that the IL-10 mRNA, although it also contains AU instability elements, is not co-regulated with the G-CSF and GM-CSF mRNAs but is regulated by a secondary factor produced in response to IL-10.

Murine interleukin-11 (IL-11) is expressed at high levels in the hippocampus and expression is developmentally regulated in the testis

IL-11, derived from a bone marrow stromal cell line, has pleiotropic effects on both hematopoietic cells and nonhematopoietic cells. However, no previous studies have systematically addressed expression of IL-11 in primary tissues in vivo and the relationship of IL-11 tissue specific gene expression and function of IL-11 is not clear. In the present study, we examined constitutive IL-11 expression in various murine adult tissues in vivo. IL-11 mRNA is expressed in a wide range of normal tissues (including hematopoietic organs) at levels only detected by RT-PCR. IL-11 protein was detected in brain and testis by Western blot analysis. The in vivo cellular distribution of IL-11 expression was examined by in situ hybridization. In brain, IL-11 message is distributed in granular layer dentate gyrus and pyramidal cell layers of hippocampus. IL-11 is also expressed in anterior horn cells and lateral column neuronal cells of the spinal cord. In testis, IL-11 mRNA is expressed in round spermatids at stage VI-IX seminiferous tubules. IL-11 expression in testis is restricted to developing spermatogonia and is developmentally regulated, since no expression is seen in mice genetically deficient in germ cells and in mice prior to sexual maturation. These expression data correlate with functional data demonstrating that IL-11 stimulates proliferation in vitro of a hippocampus neuronal progenitor cell line and administration of IL-11 in vivo accelerates recovery of spermatogenesis after cytotoxic therapy. These studies suggest that IL-11 may be an important regulator in neural and testicular function.

Interleukin (IL)-11--mediated signal transduction

IL-11 is a multifunctional cytokine biologically related to IL-6, leukemia inhibitory factor (LIF), oncostatin M (OSM) and ciliary neurotrophic factor (CNTF). It has been shown that these cytokines can utilize common signal transducer, gp130. We have demonstrated that Jak tyrosine kinases, MAP kinases and pp90rsk are highly activated by IL-11 and related cytokines. In addition, we have identified pp90rsk as one of the H7 sensitive protein kinases critical for primary response gene expression induced by IL-11. Furthermore, activation of 3CH134 (a MAP kinase phosphatase) gene by IL-11 suggested that a MAP kinase phosphatase may be involved in IL-11-mediated signal transduction. Our data also suggested that tyrosine phosphorylation of Stat91 and related transcriptional factors is involved in IL-11 signaling but is not sufficient for the activation of primary response genes such as JunB, tis11, tis8 and MAP kinase phosphatase in mouse preadipocytes. The understanding of signal transduction pathways mediated by IL-11 and related cytokines may help to define the common and unique biological properties of these growth factors.