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Cytokine Signaling (cytokine + signaling)
Selected AbstractsEarly growth response 2 regulates the survival of thymocytes during positive selectionEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 1 2010Victoria J. Lawson Abstract The early growth response (Egr) transcription factor family regulates multiple steps during T-cell development. We examine here the role played by Egr2 in positive selection. In double-positive cells, Egr2 is upregulated immediately following TCR ligation, and its expression requires both the MAPK and calcineurin signaling pathways. Inducible transgenic and knockout mice were generated to cause gain- or loss-of-function of Egr2 in double-positive cells, and had reciprocal effects; more mature single-positive cells were made when Egr2 was overexpressed, and fewer when Egr2 was absent. These defects were associated with changes in the survival of positively selected cells rather than perturbation of positive selection or immediate post-selection signaling. The survival function of Egr2 at least partly depends upon its ability to activate the cytokine-mediated survival pathway, likely through negative regulation of both the IL-7R and suppressor of cytokine signaling 1 (Socs1), the molecular switch whose downregulation normally results in restored responsiveness to cytokine signaling following selection. While gain of Egr2 caused a decrease in Socs1 mRNA, loss of Egr2 resulted in downregulation of IL-7R, upregulation of Socs1, and inhibition of Stat5 phosphorylation and IL-7-mediated survival post-selection. Therefore, expression of Egr2 following positive selection links the initial TCR signaling event to subsequent survival of signaled cells. [source] The dual function of hepatic SOCS3 in insulin resistance in vivoGENES TO CELLS, Issue 2 2007Takehiro Torisu Inflammation associates with insulin resistance, which dysregulates nutrient homeostasis and leads to diabetes. The suppressor of cytokine signaling 3 (SOCS3), which is induced by pro-inflammatory cytokines, such as TNF, and IL-6, has been implicated in inflammation-mediated insulin resistance in the liver and adipocytes. However, no genetic evidence has been provided for the involvement of SOCS3 on insulin resistance. Here, we generated hepatocyte-specific SOCS3-deficient (L-SOCS3 cKO) mice and examined insulin sensitivity. Being consistent with a previous idea, the loss of SOCS3 in the liver apparently improved insulin sensitivity. However, unexpectedly, L-SOCS3 cKO mice exhibited obesity and systemic insulin resistance with age. Insulin signaling was rather suppressed in muscles, suggesting that deletion of the SOCS3 gene in the liver modulates insulin sensitivity in other organs. Anti-inflammatory reagent, sodium salicylate, partial improved insulin resistance of aged L-SOCS3 cKO mice, suggesting that enhanced inflammatory status is associated with the phenotype of these mice. STAT3 was hyperactivated and acute-phase proteins were elevated in L-SOCS3 cKO mice liver, which were reduced by sodium salicylate treatment. We conclude that hepatic SOCS3 is a mediator of insulin resistance in the liver; however, lack of SOCS3 in the liver promotes systemic insulin resistance by mimicking chronic inflammation. [source] Involvement of gp130-associated cytokine signaling in Müller cell activation following optic nerve lesionGLIA, Issue 7 2010Matthias Kirsch Abstract Ciliary neurotrophic factor (CNTF) and the related cytokine leukemia inhibitory factor (LIF) have been implicated in regulating astrogliosis following CNS lesions. Application of the factors activates astrocytes in vivo and in vitro, and their expression as well as their receptors is upregulated after brain injury. Here, we investigated their function by studying Müller cell activation induced by optic nerve crush in CNTF- and LIF-deficient mice, and in animals with deficiencies in cytokine signaling pathways. In the retina of CNTF,/, mice, basal GFAP expression was reduced, but unexpectedly, injury-induced upregulation in activated Müller cells was increased during the first 3 days after lesion as compared to wild-type animals and this corresponded with higher phosphorylation level of STAT3, an indicator of cytokine signaling. The observation that LIF expression was strongly upregulated in CNTF,/, mice but not in wild-type animals following optic nerve lesion provided a possible explanation. In fact, additional ablation of the LIF gene in CNTF/LIF double knockout mice almost completely abolished early lesion-induced GFAP upregulation in Müller cells and STAT3 phosphorylation. Early Müller cell activation was also eliminated in LIF,/, mice, despite normal CNTF levels, as well as in mutants deficient in gp130/JAK/STAT signaling and in conditional STAT3 knockout mice. Our results demonstrate that LIF signaling via the gp130/JAK/STAT3 pathway is required for the initiation of the astrogliosis-like reaction of retinal Müller cells after optic nerve injury. A potential role of CNTF was possibly masked by a compensatory increase in LIF signaling in the absence of CNTF. © 2010 Wiley-Liss, Inc. [source] IFN-,-induced BACE1 expression is mediated by activation of JAK2 and ERK1/2 signaling pathways and direct binding of STAT1 to BACE1 promoter in astrocytesGLIA, Issue 3 2007Hyun Jin Cho Abstract ,-Site APP cleaving enzyme 1 (BACE1) is an essential enzyme for the production of , amyloid. Since we found that injection of interferon-, (IFN-,) into young mouse brains increased BACE1 expression in astrocytes, we investigated molecular mechanisms underlying this process by cloning a putative BACE1 promoter. BACE1 promoter activity was differentially regulated by IFN-, in a region specific manner and down-regulated by an inhibitor of Janus kinase 2 (JAK2). A dominant negative mutant of signal transducer and activator of transcription 1 (STAT1) expression suppressed BACE1 promoter activity, and this was rescued by transfecting wild type STAT1. Electrophoretic mobility shift assay and promoter activity assays indicated that STAT1 binds directly to the putative STAT1 binding sequence of BACE1 promoter. Because IFN-, treatment induced STAT1 phosphorylation, we examined whether the expression of a suppressor of cytokine signaling (SOCS), negative regulator of JAK2, suppresses BACE1 promoter activity. The results show that SOCS1 or SOCS3 expression suppressed BACE1 promoter by blocking phosphorylation of Tyr701 residue in STAT1. Also, because IFN-, treatment specifically potentiated extracellular signal regulated MAP kinase (ERK) 1/2 activation, pretreatment of mitogen-activated or extracellular signal-regulated protein kinase (MEK) inhibitor, PD98059, significantly attenuated IFN-,-induced BACE1 promoter activity and protein expression through blocking phosphorylation of Ser727 residue in STAT1, suggesting that ERK1/2 is associated with IFN-,-induced STAT1 signaling cascade. Taken together, our results suggest that IFN-, activates JAK2 and ERK1/2 and then phosphorylated STAT1 binds to the putative STAT1 binding sequences in BACE1 promoter region to modulate BACE1 protein expression in astrocytes. © 2006 Wiley-Liss, Inc. [source] Crystal Structure of an EMAP-II-Like Cytokine Released from a Human tRNA SynthetaseHELVETICA CHIMICA ACTA, Issue 4 2003Xiang-Lei Yang Aminoacyl-tRNA synthetases catalyze the first step of protein synthesis by aminoacylation of tRNAs. Remarkably, biological fragments of two human enzymes , tyrosyl-tRNA synthetase (TyrRS) and tryptophanyl-tRNA synthetase , are active cytokines produced by proteolysis or alternative splicing. One is a C-terminal fragment of TyrRS (C-TyrRS) that has potent activity for chemotaxis of leukocytes and monocytes and for stimulating production of other cytokines. Significantly, the cytokine activity of C-TyrRS is absent in the context of the full-length native protein. Unknown is the mechanism by which domain-release from the dimeric native protein activates the cytokine. Here, the crystal structure of C-TyrRS is presented at 2.2,Å resolution. This structure is similar to that of endothelial monocyte-activating protein II (EMAP-II), with critical residues of a heptapeptide element important for chemotaxis activity exposed on the first strand of a , -barrel of the monomeric unit. In contrast, the same residues of C-TyrRS are buried in an operational model for native TyrRS. Importantly, C-TyrRS is shown here to be monomeric when released from dimeric native TyrRS. Further analysis suggests that the critical residues are exposed when tRNA is bound. Thus, tRNA binding to native TyrRS may be an additional or alternative way to activate cytokine signaling. [source] Sites and mechanisms of insulin resistance in nonobese, nondiabetic patients with chronic hepatitis C,HEPATOLOGY, Issue 3 2009Ester Vanni Chronic hepatitis C (CHC) has been associated with type 2 diabetes and insulin resistance, but the extent of impairment in insulin action, the target pathways involved, and the role of the virus per se have not been defined. In this study, we performed a euglycemic hyperinsulinemic clamp (1 mU · minute,1 · kg,1) coupled with infusion of tracers ([6,6- 2H2]glucose, [2H5]glycerol) and indirect calorimetry in 14 patients with biopsy-proven CHC, who were selected not to have any features of the metabolic syndrome, and in seven healthy controls. We also measured liver expression of inflammatory cytokines/mediators and tested their association with the metabolic parameters. Compared to controls, in patients with CHC: (1) total glucose disposal (TGD) during the clamp was 25% lower (P = 0.003) due to impaired glucose oxidation (P = 0.0002), (2) basal endogenous glucose production (EGP) was 20% higher (P = 0.011) and its suppression during the clamp was markedly reduced (P = 0.007), and (3) glycerol appearance was not different in the basal state or during the clamp, but lipid oxidation was less suppressed by insulin (P = 0.004). Lipid oxidation was higher in patients with CHC who had more steatosis and was directly related to EGP, TGD, and glucose oxidation. The decreased insulin-stimulated suppression of EGP was associated with increased hepatic suppressor of cytokine signaling 3 (SOCS3; P < 0.05) and interleukin-18 (P < 0.05) expression. Conclusion: Hepatitis C infection per se is associated with peripheral and hepatic insulin resistance. Substrate competition by increased lipid oxidation and possibly enhanced hepatic expression of inflammatory cytokines/mediators could be involved in the defective glucose regulation. (HEPATOLOGY 2009.) [source] Loss of signal transducer and activator of transcription 5 leads to hepatosteatosis and impaired liver regeneration,HEPATOLOGY, Issue 2 2007Yongzhi Cui Growth hormone controls many facets of a cell's biology through the transcription factors Stat5a and Stat5b (Stat5). However, whole body deletion of these genes from the mouse does not provide portentous information on cell-specific cytokine signaling. To explore liver-specific functions of Stat5, the entire Stat5 locus was deleted in hepatocytes using Cre-mediated recombination. Notably, Stat5-mutant mice developed fatty livers and displayed impaired proliferation of hepatocytes upon partial hepatectomy (PHx). Loss of Stat5 led to molecular consequences beyond the reduced expression of Stat5 target genes, such as those encoding suppressor of cytokine signaling 2 (SOCS2), Cish, and insulin-like growth factor 1 (IGF-1). In particular, circulating growth hormone levels were increased and correlated with insulin resistance and increased insulin levels. Aberrant growth hormone (GH)-induced activation of the transcription factors Stat1 and Stat3 was observed in mutant livers. To test whether some of the defects observed in liver-specific Stat5 deficient mice were due to aberrant Stat1 expression and activation, we generated Stat1,/, mice with a hepatocyte-specific deletion of Stat5. Concomitant loss of both Stat5 and Stat1 restored cell proliferation upon PHx but did not reverse fatty liver development. Thus the molecular underpinnings of some defects observed in the absence of Stat5 are the consequence of a deregulated activation of other signal transducers and activators of transcription (STAT) family members. Conclusion: Aberrant cytokine-Stat5 signaling in hepatocytes alters their physiology through increased activity of Stat1 and Stat3. Such cross-talk between different pathways could add to the complexity of syndromes observed in disease. (HEPATOLOGY 2007.) [source] Characterization of cecal gene expression in a differentially susceptible mouse model of bacterial-induced inflammatory bowel diseaseINFLAMMATORY BOWEL DISEASES, Issue 7 2007Matthew H. Myles DVM Abstract Background: A/JCr mice develop typhlitis in response to Helicobacter hepaticus infection, whereas C57BL/6 mice coexist with this bacterium in a "commensal" relationship and do not develop disease even during prolonged colonization. Methods: To determine mechanisms that control this balance between responsiveness and nonresponsiveness, the mucosal response of A/JCr and C57BL/6 mice to acute H. hepaticus colonization was evaluated using genome-wide profiling. Transcription levels for a subset of gene discoveries were then evaluated longitudinally by semiquantitative real-time reverse-transcriptase polymerase chain reaction (RT-PCR) to identify changes in gene expression that occur during progression from the acute to chronic phase of colonization. To determine whether chronic mucosal inflammation in A/JCr mice was mediated through a Th1 mechanism, as was inferred from the gene expression data, mice with typhlitis were treated with neutralizing antibody targeting IL-12/23p40 or IFN-gamma and the response to treatment was determined by cecal lesion severity and transcription of disease-related genes. Results: A/JCr mice had a biphasic expression of proinflammatory genes that corresponded with the acute and chronic phases of disease. In contrast, C57BL/6 mice exhibited a less robust acute transcriptional response that waned by day 30 postinoculation. Sustained upregulation of proinflammatory signals and responsiveness to anti-IL-12/23p40 and anti-IFN-, antibody suggests that inflammation in A/JCr mice was mediated through a Th1 mechanism. Prolonged upregulation of SOCS3 during the acute response to colonization suggests that C57BL/6 mice maintain mucosal homeostasis, at least in part by attenuating responsiveness to cytokine signaling. Conclusions: Collectively, these findings provide a foundation for understanding the immunological mechanisms that confer resistance or susceptibility to H. hepaticus -induced typhlitis. (Inflamm Bowel Dis 2007) [source] Involvement of the JAK-STAT pathway and SOCS3 in the regulation of adiponectin-generated reactive oxygen species in murine macrophage RAW 264 cellsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 3 2010Sumio Akifusa Abstract Adiponectin is a protein hormone produced by differentiating adipocytes and has been proposed to have anti-diabetic and immunosuppressive properties. We previously reported that the globular form of adiponectin (gAd) induces the generation of reactive oxygen species (ROS) and nitric oxide (NO), followed by caspase-dependent apoptotic cell death in RAW 264 cells. Here, we demonstrate that gAd-induced ROS generation and apoptosis were diminished by suppressor of cytokine signaling 3 (SOCS3). The phosphorylation level of signal transducer and activator of transcription (STAT) 3 detected by Western blotting was highest at 20,min in gAd-treated RAW 264 cells. This phosphorylation was inhibited by AG490, a specific inhibitor of janus-activator kinase (JAK). The gAd-induced ROS and NO were reduced by administration of AG490 and Jak-2-specific siRNA in RAW 264 cells. The gAd stimulation transiently induced SOCS3 mRNA expression and protein production. We examined SOCS3-overexpressing RAW 264 cells to investigate the role of the JAK-STAT pathway in gAd-induced ROS and NO generation. SOCS3 overexpression significantly reduced both ROS and NO generation. Additionally, gAd-induced caspase activation and apoptotic cell death were reduced in SOCS3 transfectants compared with vector control transfectants. These results suggest that the JAK-STAT pathway, which can be suppressed by SOCS3 expression, is involved in gAd-induced ROS and NO generation followed by apoptotic cell death. J. Cell. Biochem. 111: 597,606, 2010. © 2010 Wiley-Liss, Inc. [source] Analyzing cell fate control by cytokines through continuous single cell biochemistryJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2009Michael A. Rieger Abstract Cytokines are important regulators of cell fates with high clinical and commercial relevance. However, despite decades of intense academic and industrial research, it proved surprisingly difficult to describe the biological functions of cytokines in a precise and comprehensive manner. The exact analysis of cytokine biology is complicated by the fact that individual cytokines control many different cell fates and activate a multitude of intracellular signaling pathways. Moreover, although activating different molecular programs, different cytokines can be redundant in their biological effects. In addition, cytokines with different biological effects can activate overlapping signaling pathways. This prospect article will outline the necessity of continuous single cell biochemistry to unravel the biological functions of molecular cytokine signaling. It focuses on potentials and limitations of recent technical developments in fluorescent time-lapse imaging and single cell tracking allowing constant long-term observation of molecules and behavior of single cells. J. Cell. Biochem. 108: 343,352, 2009. © 2009 Wiley-Liss, Inc. [source] N-Ace: Using solvent accessibility and physicochemical properties to identify protein N-acetylation sitesJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 15 2010Tzong-Yi Lee Abstract Protein acetylation, which is catalyzed by acetyltransferases, is a type of post-translational modification and crucial to numerous essential biological processes, including transcriptional regulation, apoptosis, and cytokine signaling. As the experimental identification of protein acetylation sites is time consuming and laboratory intensive, several computational approaches have been developed for identifying the candidates of experimental validation. In this work, solvent accessibility and the physicochemical properties of proteins are utilized to identify acetylated alanine, glycine, lysine, methionine, serine, and threonine. A two-stage support vector machine was applied to learn the computational models with combinations of amino acid sequences, and the accessible surface area and physicochemical properties of proteins. The predictive accuracy thus achieved is 5% to 14% higher than that of models trained using only amino acid sequences. Additionally, the substrate specificity of the acetylated site was investigated in detail with reference to the subcellular colocalization of acetyltransferases and acetylated proteins. The proposed method, N-Ace, is evaluated using independent test sets in various acetylated residues and predictive accuracies of 90% were achieved, indicating that the performance of N-Ace is comparable with that of other acetylation prediction methods. N-Ace not only provides a user-friendly input/output interface but also is a creative method for predicting protein acetylation sites. This novel analytical resource is now freely available at http://N-Ace.mbc.NCTU.edu.tw/. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010 [source] GeneChip® analysis after acute spinal cord injury in ratJOURNAL OF NEUROCHEMISTRY, Issue 4 2001Guoqing Song Spinal cord injury (SCI) leads to induction and/or suppression of several genes, the interplay of which governs the neuronal death and subsequent loss of motor function. Using GeneChip®, the present study analyzed changes in the mRNA abundance at 3 and 24 h after SCI in adult rats. SCI was induced at T9 level by the New York University impactor by dropping a 10-g weight from a height of 25 mm. Several transcription factors, immediate early genes, heat-shock proteins, pro-inflammatory genes were up-regulated by 3 h, and persisted at 24 h, after SCI. On the other hand, some neurotransmitter receptors and transporters, ion channels, kinases and structural proteins were down-regulated by 3 h, and persisted at 24 h, after SCI. Several genes that play a role in growth/differentiation, survival and neuroprotection were up-regulated at 24 h after SCI. Using real-time quantitative PCR, the changes observed by GeneChip® were confirmed for seven up-regulated (interleukin-6, heat-shock protein-70, heme oxygenase-1, suppressor of cytokine signaling 2, suppressor of cytokine signaling 3, interferon regulatory factor-1, neuropeptide Y), two down-regulated (vesicular GABA transporter and cholecystokinin precursor) and two unchanged (Cu/Zn-superoxide dismutase and phosphatidyl inositol-3-kinase) genes. The present study shows that inflammation, neurotransmitter dysfunction, increased transcription, ionic imbalance and cytoskeletal damage starts as early as 3 h after SCI. In addition to these effects, 24 h after SCI the repair and regeneration process begins in an attempt to stabilize the injured spinal cord. [source] Multiple mechanisms that prevent excessive brain inflammationJOURNAL OF NEUROSCIENCE RESEARCH, Issue 11 2007Myung-Soon Yang Abstract Inflammation of the injured brain has a double-edged effect. Inflammation protects the brain from infection, but it aggravates injury. Furthermore, brain inflammation is considered a risk factor for neurodegenerative disorders, such as Alzheimer's and Parkinson's diseases. Emerging evidence supports the activation of negative regulatory mechanisms during this process to prevent prolonged and extensive inflammation. The inflammatory stimulators themselves or products of inflammatory cells may induce the expression of negative feedback regulators, such as suppressor of cytokine signaling (SOCS)-family proteins, antioxidant enzymes, and antiinflammatory cytokines. Furthermore, death of activated microglia (major inflammatory cells in the brain) may regulate brain inflammation. Astrocytes, the most abundant cells in the brain, may also act in preventing microglial overactivation. Therefore, we propose that the extent and duration of brain inflammation is tightly regulated through the cooperation of multiple mechanisms to maximize antipathogenic effects and minimize tissue damage. © 2007 Wiley-Liss, Inc. [source] Effect of pro-inflammatory and immunoregulatory cytokines on human tenocytesJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 8 2010Thilo John Abstract Tendon injury induces a local inflammatory response, characterized by the induction of pro-inflammatory cytokines. The aim of the present study was to analyze the effects of TNF,, IL-6 and IL-10 on key parameters of tendon homeostasis. Cultured primary human tenocytes were treated with the recombinant cytokines IL-6, IL-10, TNF,, or combinations of TNF, with IL-6 and IL-10 (10 ng/mL, 6, 24 h). Expression of type I collagen, elastin, MMP-1, TNF,, IL-1,, IL-6, IL-10, and suppressors of cytokine signaling (SOCS1, 3) was analyzed with the use of RTD-PCR, immunocytochemistry, and Western blot analysis. In response to TNF,, tenocytes reduced their type I collagen deposition but increased their elastin gene expression and highly upregulated their expression for MMP-1, pro-inflammatory (TNF,, IL-1,) and immunoregulatory (IL-6, IL-10) cytokines. TNF, stimulation augmented SOCS1, whereas SOCS3 expression in tenocytes was also induced by IL-6. The treatment of tenocytes with IL-6 and IL-10 had no effect on cytokine expression. Neither IL-6 nor IL-10 modulated the observed effects of TNF, significantly. These results indicate that TNF, strongly activates the tenocytes to amplify their own TNF, expression and, subsequently, that of other regulatory cytokines and matrix degrading enzymes. However, the impact of IL-6 and IL-10 on tenocytes remains unclear. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:1071,1077, 2010 [source] Sequence of administration and methylation of SOCS3 may govern response to gemtuzumab ozogamicin in combination with conventional chemotherapy in patients with refractory or relapsed acute myelogenous leukemia (AML),AMERICAN JOURNAL OF HEMATOLOGY, Issue 7 2010Iris Middeldorf In older patients suffering from acute myelogenous leukemia (AML), aggressive chemotherapy is accompanied with high treatment-related morbidity and mortality. Gemtuzumab ozogamicin (GO), a humanized monoclonal anti-CD33 antibody, represents a well tolerated treatment option, but optimal treatment schedules are still unknown. Additionally, Suppressor of cytokine signaling 3 (SOCS3) inhibits the CD33-induced block on cytokine-induced proliferation. Consequently, a variable response of AML cells to anti-CD33-targeted therapy may be caused by modulation of SOCS3 expression. Twenty-four patients with refractory or relapsed CD33-positive AML received GO as a single agent before or after conventional chemotherapy. The methylation status of the SOCS3 CpG island was assessed by methylation-specific polymerase chain reaction. Response (RR) and overall survival (OS) were significantly higher in 16 patients receiving chemotherapy before GO (RR 81%, OS 14.8 months) compared to three patients who received GO single agent therapy (RR 33%, OS 7.2 months) or 16 with GO before chemotherapy (RR 0% OS 2.2 months, P = 0.01 for RR and P < 0.001 for OS). Methylation of the SOCS3 CpG island was found in 8/24 patients. There was a trend towards a higher RR and longer OS in patients with SOCS3 hypermethylation (RR 86%, OS 25.1 months) compared to unmethylated SOCS3 (RR 56%, OS 10.3 months, P = 0.09). Administration of GO a few days after chemotherapy seems to provide better response and survival compared to administration of GO directly before chemotherapy. The potential role of SOCS3 hypermethylation as a biomarker should be further investigated in patients undergoing GO containing therapies. Am. J. Hematol., 2010. © 2010 Wiley-Liss, Inc. [source] Selective functional inhibition of JAK-3 is sufficient for efficacy in collagen-induced arthritis in miceARTHRITIS & RHEUMATISM, Issue 8 2010Tsung H. Lin Objective All ,-chain cytokines signal through JAK-3 and JAK-1 acting in tandem. We undertook this study to determine whether the JAK-3 selective inhibitor WYE-151650 would be sufficient to disrupt cytokine signaling and to ameliorate autoimmune disease pathology without inhibiting other pathways mediated by JAK-1, JAK-2, and Tyk-2. Methods JAK-3 kinase selective compounds were characterized by kinase assay and JAK-3,dependent (interleukin-2 [IL-2]) and ,independent (IL-6, granulocyte,macrophage colony-stimulating factor [GM-CSF]) cell-based assays measuring proliferation or STAT phosphorylation. In vivo, off-target signaling was measured by IL-22, and erythropoietin (EPO),mediated models, while on-target signaling was measured by IL-2,mediated signaling. Efficacy of JAK-3 inhibitors was determined using delayed-type hypersensitivity (DTH) and collagen-induced arthritis (CIA) models in mice. Results In vitro, WYE-151650 potently suppressed IL-2,induced STAT-5 phosphorylation and cell proliferation, while exhibiting 10,29-fold less activity against JAK-3,independent IL-6, or GM-CSF,induced STAT phosphorylation. Ex vivo, WYE-151650 suppressed IL-2,induced STAT phosphorylation, but not IL-6,induced STAT phosphorylation, as measured in whole blood. In vivo, WYE-151650 inhibited JAK-3,mediated IL-2,induced interferon-, production and decreased the natural killer cell population in mice, while not affecting IL-22,induced serum amyloid A production or EPO-induced reticulocytosis. WYE-151650 was efficacious in mouse DTH and CIA models. Conclusion In vitro, ex vivo, and in vivo assays demonstrate that WYE-151650 is efficacious in mouse CIA despite JAK-3 selectivity. These data question the need to broadly inhibit JAK-1,, JAK-2,, or Tyk-2,dependent cytokine pathways for efficacy. [source] BAFF synthesis by rheumatoid synoviocytes is positively controlled by ,5,1 integrin stimulation and is negatively regulated by tumor necrosis factor , and toll-like receptor ligandsARTHRITIS & RHEUMATISM, Issue 10 2007Ghada Alsaleh Objective It was recently demonstrated that synoviocytes (FLS) from rheumatoid arthritis (RA) patients express BAFF transcripts that are up-regulated by tumor necrosis factor , (TNF,) and interferon-, (IFN,). Thus, BAFF increases in RA target cells might be related to activation of the receptors of innate immunity. The purpose of this study was to determine whether ligands of Toll-like receptor 2 (TLR-2), TLR-4, TLR-9, and ,5,1 integrin are able to induce BAFF synthesis by RA FLS. Methods Quantitative reverse transcription,polymerase chain reaction analyses and enzyme-linked immunosorbent assays were performed to evaluate BAFF messenger RNA induction and BAFF release from FLS after stimulation by ligands for TLR-2, TLR-4, TLR-9, ,5,1 integrin (bacterial lipopeptide [BLP] palmitoyl-3-cysteine-serine-lysine-4, lipopolysaccharide [LPS], CpG, and protein I/II, respectively), TNF,, and IFN,. Results In contrast to IFN,, neither TNF,, LPS, BLP, nor CpG induced the de novo synthesis and release of BAFF by FLS. Priming of cells with IFN, did not have a synergistic effect on BAFF synthesis by FLS stimulated with bacterial products known as pathogen-associated molecular patterns. Moreover, we found that IFN,-induced BAFF synthesis is inhibited by simultaneous stimulation with either TLR ligands or TNF,. We also showed that interplay between TLRs, TNF receptors, and IFN, signaling induces the expression of suppressor of cytokine signaling 1 (SOCS-1) and SOCS-3 and reduces IFN,-dependent STAT-1 phosphorylation, which might explain this inhibition. In contrast, we demonstrated that stimulation of ,5,1 integrin can induce BAFF synthesis and release per se and that stimulation of this pathway has no inhibitory effect on IFN,-induced BAFF synthesis. Conclusion Our findings indicate that BAFF secretion by resident cells in target organs of autoimmunity is tightly regulated by innate immunity, with positive and negative controls, depending on the receptors and the pathways triggered. [source] Insulin-like growth factor-I receptor signal transduction and the Janus Kinase/Signal Transducer and Activator of Transcription (JAK-STAT) pathwayBIOFACTORS, Issue 1 2009Eddy Himpe Abstract The insulin-like growth factor IGF-I is an important fetal and postnatal growth factor, which is also involved in tissue homeostasis via regulation of proliferation, differentiation, and cell survival. To understand the role of IGF-I in the pathophysiology of a variety of disorders, including growth disorders, cancer, and neurodegenerative diseases, a detailed knowledge of IGF-I signal transduction is required. This knowledge may also contribute to the development of new therapies directed at the IGF-I receptor or other signaling molecules. In this review, we will address IGF-I receptor signaling through the JAK/STAT pathway in IGF-I signaling and the role of cytokine-induced inhibitors of signaling (CIS) and suppressors of cytokine signaling (SOCS). It appears that, in addition to the canonical IGF-I signaling pathways through extracellular-regulated kinase (ERK) and phosphatidylinositol-3 kinase (PI3K)-Akt, IGF-I also signals through the JAK/STAT pathway. Activation of this pathway may lead to induction of SOCS molecules, well-known feedback inhibitors of the JAK/STAT pathway, which also suppress of IGF-I-induced JAK/STAT signaling. Furthermore, other IGF-I-induced signaling pathways may also be modulated by SOCS. It is conceivable that the effect of these classical inhibitors of cytokine signaling directly affect IGF-I receptor signaling, because they are able to associate to the intracellular part of the IGF-I receptor. These observations indicate that CIS and SOCS molecules are key to cross-talk between IGF-I receptor signaling and signaling through receptors belonging to the hematopoietic/cytokine receptor superfamily. Theoretically, dysregulation of CIS or SOCS may affect IGF-I-mediated effects on body growth, cell differentiation, proliferation, and cell survival. © 2009 International Union of Biochemistry and Molecular Biology, Inc. [source] Gene expression in arcuate nucleus-median eminence of rats treated with leptin or ciliary neurotrophic factorBIOFACTORS, Issue 2 2007Suresh Ambati Abstract Ciliary neurotrophic factor (CNTF) and leptin are cytokine-like hormones and act on their corresponding receptors in the hypothalamic arcuate nucleus (ARC). The present study was designed to assess effects of intracerebroventricular (ICV) injection of leptin and CNTF on gene expression in micropunched hypothalamic arcuate nucleus-median eminence (ARCME) complex samples from rats. Male Sprague Dawley rats were implanted with lateral cerebroventricular cannulas for administration of control, 10 ,g/d leptin or 5 ,g/d CNTF for four days. Real-time Taqman RT-PCR was used to quantitatively compare the mRNA levels of selected genes in the ARC-ME complex. Leptin and CNTF increased ARC-ME mRNA levels of signal transducer and activator of transcription 3 (STAT3) by 64.5 and 124.7% (p < 0.01), suppressor of cytokine signaling 3 (SOCS3) by 258.9 and 1063.9% (p < 0.01), cocaine and amphetamine regulated transcript (CART) by 102.7 and 123.1% (p < 0.01), and proopiomelanocortin (POMC2) by 374.1 and 264.9% (p < 0.01), respectively. Leptin increased growth hormone releasing hormone (GHRH) by 309.9% (p < 0.01), while CNTF increased janus kinase 2 (JAK2) mRNA by 31.7% (p < 0.01) and decreased gonadotropin releasing hormone 1 (GNRH1) by 59.7% (p < 0.01), mitogen activated protein kinase 1 (MAPK1) by 19.4% (p < 0.05) and tyrosine hydroxylase (TH) by 74.5% (p < 0.05). Significant reduction in daily food intake and body weights by both the treatments was observed. Also, decrease in weights of fat pads was concomitant with lowered serum insulin and leptin levels. Our findings show that leptin and CNTF engage both convergent and divergent pathways involved in feeding, cellular signaling, inflammation, and other related regulatory systems. [source] Differential stimulation-induced receptor localization in lipid rafts for interleukin-6 family cytokines signaling through the gp130/leukemia inhibitory factor receptor complexJOURNAL OF NEUROCHEMISTRY, Issue 3 2007Martha D. Port Abstract Leukemia inhibitory factor (LIF) and ciliary neurotrophic factor (CNTF) are cytokines which signal through receptor complexes that include the receptor subunits glycoprotein 130 (gp130) and the LIF receptor (LIFR), but CNTF also requires the non-signal transducing CNTF receptor (CNTFR) for binding. We show here that in IMR-32 neuronal cells endogenously expressing the receptor subunits for LIF and CNTF, CNTFR, but not gp130 or LIFR, is found in detergent-resistant lipid rafts. In addition, stimulation of these cells with CNTF resulted in a rapid translocation of a portion of gp130 and LIFR into detergent-resistant lipid rafts while an equivalent stimulation with LIF did not. Disruption of lipid rafts by cholesterol depletion of cell membranes blocked the CNTF-induced translocation of LIFR and gp130. Interestingly, while cholesterol-depletion did not inhibit signal transducer and activator of transcription 3 phosphorylation by either CNTF or LIF stimulation, it strongly inhibited both CNTF- and LIF-mediated phosphorylation of extracellular signal-regulated kinases 1 and 2 and Akt. LIF and CNTF generally appear to have redundant effects in cells responsive to both cytokines. Intriguingly, the data presented here suggest a possible mechanism whereby CNTF or other cytokines that signal through CNTFR could generate signals distinct from those elicited by cytokines such as LIF which utilize a LIFR/gp130 heterodimer, via association with or exclusion from lipid rafts. [source] | ||||||||||||||||