Internalization of the interleukin 6 signal transducer gp130 does not require activation of the Jak/STAT pathway.
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ABSTRACT:
SUBMITTER: Thiel S
PROVIDER: S-EPMC1219106 | biostudies-other | 1998 Feb
REPOSITORIES: biostudies-other
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Project description:The family of cytokines signalling through the common receptor subunit gp130 comprises interleukin (IL)-6, IL-11, leukaemia inhibitory factor, oncostatin M, ciliary neurotrophic factor and cardiotrophin-1. These so-called IL-6-type cytokines play an important role in the regulation of complex cellular processes such as gene activation, proliferation and differentiation. The current knowledge on the signal-transduction mechanisms of these cytokines from the plasma membrane to the nucleus is reviewed. In particular, we focus on the assembly of receptor complexes after ligand binding, the activation of receptor-associated kinases of the Janus family, and the recruitment and phosphorylation of transcription factors of the STAT family, which dimerize, translocate to the nucleus, and bind to enhancer elements of respective target genes leading to transcriptional activation. The important players in the signalling pathway, namely the cytokines and the receptor components, the Janus kinases Jak1, Jak2 and Tyk2, the signal transducers and activators of transcription STAT1 and STAT3 and the tyrosine phosphatase SHP2 [SH2 (Src homology 2) domain-containing tyrosine phosphatase] are introduced and their structural/functional properties are discussed. Furthermore, we review various mechanisms involved in the termination of the IL-6-type cytokine signalling, namely the action of tyrosine phosphatases, proteasome, Jak kinase inhibitors SOCS (suppressor of cytokine signalling), protein inhibitors of activated STATs (PIAS), and internalization of the cytokine receptors via gp130. Although all IL-6-type cytokines signal through the gp130/Jak/STAT pathway, the comparison of their physiological properties shows that they elicit not only similar, but also distinct, biological responses. This is reflected in the different phenotypes of IL-6-type-cytokine knock-out animals.
| S-EPMC1219691 | biostudies-other
Project description:ObjectiveInterferon-gamma (IFN-γ) is overexpressed in rheumatoid synovium and thought to be involved in the pathogenesis of rheumatoid arthritis (RA). In this study, we examined our hypothesis that IFN-γ activates innate immune cells and upregulates inflammatory cytokines. Peripheral blood neutrophils were stimulated with IFN-γ in the presence or absence of Janus kinase (JAK) inhibitors. Interleukin-6 (IL-6) mRNA and protein expression were analyzed using real-time polymerase chain reaction (PCR) method and enzyme-linked immunosorbent assay. Protein phosphorylation of JAKs or STAT1 was assessed by Western blot using phospho-specific antibodies.ResultsIFN-γ stimulation induces IL-6 expression in protein and mRNA levels in human neutrophils. Furthermore, IFN-γ stimulation induces JAK1/JAK2 phosphorylation and downstream signal transducer and activator of transcription (STAT) 1 phosphorylation in human neutrophils. Although all JAKi, blocked IFN-γ-induced JAK1.2/STAT1 phosphorylation at higher concentrations (100 nM), baricitinib most efficiently inhibited IFN-γ-induced JAK1.2/STAT1 phosphorylation at lower concentrations (≤ 25 nM). Among these JAKi, baricitinib was the most potent regulator for IFN-γ-induced IL-6 production in human neutrophils. Our data indicate that IFN-γ upregulates IL-6 production via the JAK1/2-STAT1 pathway in human innate immune cells. Furthermore, this IFN-γ-mediated IL-6 induction via JAK/STAT was downregulated by JAKi.
| S-EPMC8666078 | biostudies-literature
Project description:Appropriately formulated quantitative computational models can support researchers in understanding the dynamic behaviour of biological pathways and support hypothesis formulation and selection by "in silico" experimentation. An obstacle to widespread adoption of this approach is the requirement to formulate a biological pathway as machine executable computer code. We have recently proposed a novel, biologically intuitive, narrative-style modelling language for biologists to formulate the pathway which is then automatically translated into an executable format and is, thus, usable for analysis via existing simulation techniques.Here we use a high-level narrative language in designing a computational model of the gp130/JAK/STAT signalling pathway and show that the model reproduces the dynamic behaviour of the pathway derived by biological observation. We then "experiment" on the model by simulation and sensitivity analysis to define those parameters which dominate the dynamic behaviour of the pathway. The model predicts that nuclear compartmentalisation and phosphorylation status of STAT are key determinants of the pathway and that alternative mechanisms of signal attenuation exert their influence on different timescales.The described narrative model of the gp130/JAK/STAT pathway represents an interesting case study showing how, by using this approach, researchers can model biological systems without explicitly dealing with formal notations and mathematical expressions (typically used for biochemical modelling), nevertheless being able to obtain simulation and analysis results. We present the model and the sensitivity analysis results we have obtained, that allow us to identify the parameters which are most sensitive to perturbations. The results, which are shown to be in agreement with existing mathematical models of the gp130/JAK/STAT pathway, serve us as a form of validation of the model and of the approach itself.
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Project description:The transmembrane glycoprotein gp130 is involved in many cytokine-mediated cellular responses and acts therein as the signal transducing receptor subunit. Interleukin-6 (IL-6) and interleukin-11 (IL-11), in complex with their specific alpha-receptors, homodimerize gp130 and, as a consequence, activate the Janus kinase (Jak)/signal transducer and activator of transcription (STAT) signalling pathway in their target cells. So far, it is not clear whether gp130 is bound to these cytokines and their specific alpha-receptor subunits through identical or different epitopes. In order to study the interaction of IL-11 and IL-11R with human gp130 the soluble form of the recently cloned human IL-11R was expressed in baculovirus-infected insect cells. By a coprecipitation binding-assay it is demonstrated that IL-11 and IL-6 compete for binding to gp130. Using deletion and point mutants of gp130 it is shown that IL-11-IL-11R and IL-6-IL-6R recognize overlapping binding motifs on gp130. Moreover, using well-established Jak-deficient cell lines we demonstrate that STAT activation by IL-11 requires Jak1. Taken together, our data support the concept that IL-6 and IL-11 activate gp130 by very similar molecular mechanisms.
| S-EPMC1219407 | biostudies-other
Project description:Th1/Th17-type T-cell responses are upregulated in Behcet's disease (BD). However, signaling pathways associated with this aberrant immune response are not clarified. Whole-genome microarray profiling was performed with human U133 (Plus 2.0) chips using messenger RNA of isolated CD14(+) monocytes and CD4(+) T cells from peripheral blood mononucleated cell (PBMC) in patients with BD (n = 9) and healthy controls (HCs) (n = 9). Flow cytometric analysis of unstimulated (US) and stimulated (phytohaemagglutinin) signal transducer and activator of transcription (STAT3) and pSTAT3 expressions of PBMCs were also analyzed (BD and HC, both n = 26). Janus family of kinase (JAK1) was observed to be upregulated in both CD14(+) monocytes (1.95-fold) and CD4(+) T lymphocytes (1.40-fold) of BD patients. Using canonical pathway enrichment analysis, JAK/STAT signaling was identified as activated in both CD14(+) monocytes (P = 9.55E-03) and in CD4(+) lymphocytes (P =8.13E-04) in BD. Interferon signaling was also prominent among upregulated genes in CD14(+) monocytes (P = 5.62E-05). Glucocorticoid receptor signaling and interleukin (IL-6) signaling were among the most enriched pathways in differentially expressed genes in CD14+ monocytes (P = 2.45E-09 and 1.00E-06, respectively). Basal US total STAT3 expression was significantly higher in BD (1.2 vs 3.45, P < 0.05). The JAK1/STAT3 signaling pathway is activated in BD, possibly through the activation of Th1/Th17-type cytokines such as IL-2, interferon (IFN-γ), IL-6, IL-17 and IL-23.
| S-EPMC4443896 | biostudies-literature
Project description:Soluble forms of the IL-6 receptor (sIL-6R) bind to the cytokine IL-6 with similar affinity as the membrane-bound IL-6R. IL-6·sIL-6R complexes initiate IL-6 trans-signaling via activation of the ubiquitously expressed membrane-bound β-receptor glycoprotein 130 (gp130). Inhibition of IL-6 trans-signaling has been shown to be favorable in numerous inflammatory diseases. Furthermore, different soluble forms of gp130 (sgp130) exist that, together with the sIL-6R, are thought to form a buffer for IL-6 in the blood. However, a functional role for the different sgp130 forms has not been described to date. Here we demonstrate that the metalloproteases ADAM10 and ADAM17 can produce sgp130 by ectodomain shedding of gp130, even though this mechanism only accounts for a minor proportion of sgp130 in the circulation. We further show that full-length sgp130 and the shorter forms sgp130-rheumatoid arthritis-associated peptide (RAPS) and sgp130-E10 are differentially expressed in a cell type- specific manner. Remarkably, full-length sgp130 is expressed by monocytes, but this expression is completely lost during differentiation into macrophages in vitro Using genetically engineered murine pre-B cells that secrete different forms of sgp130, we found that these secreted sgp130 proteins are able to prevent trans-signaling-driven cell proliferation of the secreting cells, whereas conditioned supernatant from these cells failed to block IL-6 trans-signaling in other cells. Thus, our data suggest that the different sgp130 forms are released from cells into their immediate surroundings and appear to form cell-associated gradients to modulate their own susceptibility for IL-6 trans-signaling.
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Project description:Angiotensinogen (AGT) is involved in the production of angiotensin II which is the main mediator of action of the rennin-angiotensin system (RAS), whereas the RAS mediates the regulation of sodium homeostasis, blood pressure, and inflammation. The present study aimed to investigate the roles of the AGT in the progression of broncopulmonary dysplasia in premature newborns. By bioinformatics analysis, AGT was found to be the major node in molecular interaction networks of BPD mouse model. Quantitative PCR and western blot analyses were applied to examine AGT expression in A549 cells which were treated with the hyperoxic condition. The AGT inhibitor Valsartan and the AGT agonist ANGII were employed to investigate the roles of AGT in cell growth and the inflammation. Results show that hyperoxic treatment induced upregulation of AGT expression in A549 cells. Overexpression of AGT resulted in the inflammation via the JAK/STAT signal pathway, ultimately suppressed the proliferation of the A549 cell. In conclusion, increased expression of AGT was demonstrated to be associated with the development and progression of BPD, and may be regarded as a promising therapeutic target for BPD.
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Project description:Estrogen, a natural immunomodulatory compound, has been shown to promote the induction of a prototype T helper 1 cytokine, interferon (IFN)-gamma, as well as to up-regulate IFNgamma-mediated proinflammatory molecules (nitric oxide, cyclooxygenase 2, monocyte chemoattractant protein 1). Because IL-12 is a major IFNgamma-inducing cytokine, in this study we investigated whether estrogen treatment of wild-type C57BL/6 mice alters IL-12-mediated signaling pathways. A recent study has shown that IL-12 activates two isoforms of signal transducer and activation of transcription (STAT) 4, a normal-sized (full-length STAT4alpha) and a truncated form (STAT4beta). Interestingly, we found that estrogen treatment preferentially up-regulates the phosphorylation of STAT4beta in splenic lymphoid cells. Time kinetic data showed the differential activation of STAT4beta in splenic lymphoid cells from estrogen-treated mice, but not in cells from placebo controls. The activation of STAT4beta was mediated by IL-12 and not IFNgamma because deliberate addition or neutralization of IL-12, but not IFNgamma, affected the activation of STAT4beta. In contrast to IL-12-induced activation of STAT4beta in cells from estrogen-treated mice, STAT4alpha was not increased, rather it tended to be decreased. In this context, STAT4alpha-induced p27(kip1) protein was decreased in concanavalin A + IL-12-activated lymphocytes from estrogen-treated mice only. By using the in vitro DNA binding assay, we confirmed the ability of pSTAT4beta to bind to the IFNgamma-activated sites (IFNgamma activation sequences)/STAT4-binding sites in estrogen-treated mice. Our data are the first to show that estrogen apparently has selective effects on IL-12-mediated signaling by preferentially activating STAT4beta. These novel findings are likely to provide new knowledge with regard to estrogen regulation of inflammation.
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Project description:Optimal T cell differentiation into effector cells with specialized functions requires the participation of cytokine receptor signals. In T helper cells, this process is controlled by chromatin changes and distal and proximal regulatory elements as well as specific transcription factors. Analogous events during cytotoxic T lymphocyte (CTL) differentiation remain to be identified. This process is known, however, to be crucially regulated by interleukin (IL)-2 receptor (R) signals. It is accompanied by the induction of perforin expression via a mechanism that does not entail proximal regulatory elements. In this report, transgenically expressed human perforin gene locus DNAs demonstrate that IL-2R signals target two IL-2-dependent enhancers approximately 15 and 1 kilobase upstream of the promoter. The most distal enhancer may also respond to TCR signals. In transient transfections, both enhancers required two identically spaced Stat-like elements for their activation, which was abolished by expression of a dominant negative signal transducer and activator of transcription (Stat)5 molecule, whereas a constitutively active Stat5 molecule bypassed the requirement for IL-2R signals. These results provide a molecular explanation for the activation of the perforin gene during CTL differentiation and complement the analysis of animals deficient in the activation of the IL-2R Stat signaling pathway by establishing perforin as a target gene.
| S-EPMC2195674 | biostudies-literature
Project description:Glycoprotein 130 (gp130) is the signal transducing receptor subunit for cytokines of the interleukin-6 (IL-6) family, and it is expressed in a multitude of cell types of the immune and nervous system. IL-6-like cytokines are not only key regulators of innate immunity and inflammation but are also essential factors for the differentiation and development of the somatosensory system. Mice with a null mutation of gp130 in primary nociceptive afferents (SNS-gp130(-/-)) are largely protected from hypersensitivity to mechanical stimuli in mouse models of pathological pain. Therefore, we set out to investigate how neuronal gp130 regulates mechanonociception. SNS-gp130(-/-) mice revealed reduced mechanosensitivity to high mechanical forces in the von Frey assay in vivo, and this was associated with a reduced sensitivity of nociceptive primary afferents in vitro. Together with these findings, transient receptor potential ankyrin 1 (TRPA1) mRNA expression was significantly reduced in DRG from SNS-gp130(-/-) mice. This was also reflected by a reduced number of neurons responding with calcium transients to TRPA1 agonists in primary DRG cultures. Downregulation of Trpa1 expression was predominantly discovered in nonpeptidergic neurons, with the deficit becoming evident during stages of early postnatal development. Regulation of Trpa1 mRNA expression levels downstream of gp130 involved the classical Janus kinase family-signal transducer and activator of transcription pathway. Our results closely link proinflammatory cytokines to the expression of TRPA1, both of which have been shown to contribute to hypersensitive pain states. We suggest that gp130 has an essential role in mechanonociception and in the regulation of TRPA1 expression.
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