Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.24 (mitogen-activated protein kinase)
 95,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Interleukin 10 (IL-10) is an anti-inflammatory cytokine produced in the rheumatoid arthritis (RA) joint by macrophages/monocytes and infiltrating peripheral blood derived lymphocytes. Recent data suggest a role for physical cell-to-cell interactions in the production of IL-10. In this report, we have investigated the signalling mechanisms involved in IL-10 production by peripheral blood-derived macrophages upon interaction with fixed CD40L transfectants. IL-10 and tumour necrosis factor alpha (TNF-alpha) are produced by macrophage colony-stimulating factor (M-CSF)-primed monocytes/macrophages in response to CD40 ligation. The utilization of the inhibitors, wortmannin and LY294002, demonstrated a role for phosphatidylinositol 3-kinase (PI3K) whereas rapamycin demonstrated p70 S6-kinase (p70S6K) involvement in the production of IL-10 by these monocytes. The production of TNF-alpha was enhanced by wortmannin and LY294002, suggesting negative regulation by PI3K; however, it was dependent on p70S6K suggesting a PI3K-independent mechanism of p70S6K activation. One alternative pathway that activates p70S6K independently of PI3K and also differentiates between IL-10 and TNF-alpha is the p42/44 mitogen-activated protein kinase (MAPK), which regulates TNF-alpha production in a PI3K-independent manner. These observations suggest that CD40 ligation induces macrophage IL-10 and TNF-alpha production, the mechanism of which is p70S6K-dependent yet bifurcates at the level of PI3K and p42/44 MAPK.
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PMID:CD40 ligation induces macrophage IL-10 and TNF-alpha production: differential use of the PI3K and p42/44 MAPK-pathways. 1179 23

Activating cells of the immune system may stimulate human immunodeficiency virus type 1 (HIV-1) replication and contribute to select pathogenic variants in vivo. Here, we examined the possible effect of a major pathway of immune activation, CD40 interaction with its ligand (CD40L), on the susceptibility of monocyte-derived macrophages (MDMs) to various HIV-1 strains. Stimulation of MDMs with CD40L led to reduced replication of R5 HIV-1(Ba-L), whereas this strongly enhanced the replication of X4 HIV-1(Lai) as well as of X4 primary isolates, and this was associated with strong cytopathic effects. The replication of X4 strains was inhibited by stromal cell-derived factor 1, an indication of the restricted usage of CXCR4 as virus coreceptor in this case. CD40L induced the activation of mitogen-activated protein kinases ERK1/ERK2 and stimulated MDMs to secrete RANTES (regulated on activation, normal T cell expressed and secreted), macrophage inflammatory protein 1alpha (MIP-1alpha), MIP-1beta, interleukin 6 (IL-6), IL-1beta, and tumor necrosis factor alpha. From this data, it may be hypothesized that activated macrophages represent a favorable environment for the replication of classically T lymphocyte-tropic X4 variants and, thus, may contribute significantly to the selection of such variants at late stages of clinical HIV-1 infection.
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PMID:CD40-activated macrophages become highly susceptible to X4 strains of human immunodeficiency virus type 1. 1183 43

CD40 is a protein on microglia that is up-regulated with interferon (IFN)-gamma and is engaged by CD40L, found on CD4+ T cells, B cells, and monocytes. These interactions may be important in central nervous system inflammatory diseases. Microglia have been shown to be a source of chemokines, whose expression plays a key role in central nervous system pathologies. We examined the expression of CD40 on microglia in human immunodeficiency virus (HIV) encephalitic brain, and the effects of CD40-CD40L interactions on the expression of chemokines by cultured microglia. We found significantly increased numbers of CD40-positive microglia in HIV-infected brain tissue. Treatment of cultured microglia with IFN-gamma and CD40L increased expression of several chemokines. IFN-gamma- and CD40L-induced MCP-1 protein was mediated by activation of the ERK1/2 MAPK pathway, and Western blot analysis demonstrated phosphorylation of ERK1/2 upon stimulation of microglia. In contrast, IFN-gamma- and CD40L-induced IP-10 protein production was mediated by the p38 MAPK pathway. Our data suggest a mechanism whereby CD40L+ cells can induce microglia to secrete chemokines, amplifying inflammatory processes seen in HIV encephalitis and multiple sclerosis, and implicate CD40-CD40L interactions as a target for interventional strategies.
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PMID:CD40-CD40L interactions induce chemokine expression by human microglia: implications for human immunodeficiency virus encephalitis and multiple sclerosis. 1183 76

We show here that CD40 mRNA and protein are expressed by neuronal cells, and are increased in differentiated versus undifferentiated N2a and PC12 cells as measured by RT-PCR, western blotting and immunofluorescence staining. Additionally, immunohistochemistry reveals that neurons from adult mouse and human brain also express CD40 in situ. CD40 ligation results in a time-dependent increase in p44/42 MAPK activation in neuronal cells. Furthermore, ligation of CD40 opposes JNK phosphorylation and activity induced by NGF-beta removal from differentiated PC12 cells or serum withdrawal from primary cultured neurons. Importantly, CD40 ligation also protects neuronal cells from NGF-beta or serum withdrawal-induced injury and affects neuronal differentiation. Finally, adult mice deficient for the CD40 receptor demonstrate neuronal dysfunction as evidenced by decreased neurofilament isoforms, reduced Bcl-x(L):Bax ratio, neuronal morphological change, increased DNA fragmentation, and gross brain abnormality. These changes occur with age, and are clearly evident at 16 months. Taken together, these data demonstrate a role of CD40 in neuronal development, maintenance and protection in vitro and in vivo.
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PMID:CD40 is expressed and functional on neuronal cells. 1184 12

One of the major unresolved questions in B cell biology is how the B cell Ag receptor (BCR) differentially signals to transduce anergy, apoptosis, proliferation, or differentiation during B cell maturation. We now report that extracellularly regulated kinase-mitogen-activated protein kinase (Erk-MAP kinase) can play dual roles in the regulation of the cell fate of the immature B cell lymphoma, WEHI-231, depending on the kinetics and context of Erk-MAP kinase activation. First, we show that the BCR couples to an early (< or =2 h) Erk-MAP kinase signal which activates a phospholipase A(2) pathway that we have previously shown to mediate collapse of mitochondrial membrane potential, resulting in depletion of cellular ATP and cathepsin B execution of apoptosis. Rescue of BCR-driven apoptosis by CD40 signaling desensitizes such early extracellularly regulated kinase (Erk) signaling and hence uncouples the BCR from the apoptotic mitochondrial phospholipase A(2) pathway. A second role for Erk-MAP kinase in promoting the growth and proliferation of WEHI-231 immature B cells is evidenced by data showing that proliferating and CD40-stimulated WEHI-231 B cells exhibit a sustained cycling pattern (8-48 h) of Erk activation that correlates with cell growth and proliferation. This growth-promoting role for Erk signaling is supported by three key pieces of evidence: 1) signaling via the BCR, under conditions that induce growth arrest, completely abrogates sustained Erk activation; 2) CD40-mediated rescue from growth arrest correlates with restoration of cycling Erk activation; and 3) sustained inhibition of Erk prevents CD40-mediated rescue of BCR-driven growth arrest of WEHI-231 immature B cells. Erk-MAP kinase can therefore induce diverse biological responses in WEHI-231 cells depending on the context and kinetics of activation.
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PMID:Differential roles for extracellularly regulated kinase-mitogen-activated protein kinase in B cell antigen receptor-induced apoptosis and CD40-mediated rescue of WEHI-231 immature B cells. 1193 39

The mechanism of CD40/CD154-induced chemokine production and its potential role in renal inflammatory disease were explored. Human proximal tubule cells maintained in primary culture were used as the experimental model. With the use of immunocytochemistry, confocal microscopy, and a cell fractionation assay, the CD40 receptor was found to be expressed in the cell membrane of the epithelial cell, and, on engagement by CD154, its cognate ligand, translocated to the cytoplasmic compartment. Engagement of CD40 by CD154 stimulated interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) production, which proceeded via receptor activation of the extracellular signal-regulated kinase (ERK)1/2, stress-activated protein kinase (SAPK)/c-Jun NH(2)-terminal kinase (JNK), and p38 mitogen-activated protein kinase (MAPK) pathways. CD40 ligation also engaged tumor necrosis factor receptor-activating factor 6 (TRAF6), as evidenced by colocalization of the activated receptor with TRAF6 in the cytoplasmic compartment, translocation of both proteins from the insoluble to the soluble cell fraction, and coimmunoprecipitation of the two proteins only under ligand-stimulated conditions. Furthermore, an antisense oligodeoxyribonucleotide targeted against TRAF6 mRNA blunted p38 and SAPK/JNK but not ERK1/2 MAPK activities, as well as IL-8 and MCP-1 production, arguing that TRAF6 is an upstream activator. The zinc chelator TPEN, but not the calcium chelator BAPTA, obliterated CD154-evoked MAPK activity and chemokine production, providing indirect evidence for protein-protein interactions playing a critical role in CD40 signaling in these cells. We conclude that in human proximal tubule cells, CD40 and TRAF6 reside in separate low-density, detergent-insoluble membrane microdomains, or rafts, and on activation translocate and associate with one another probably via zinc-finger domains in the soluble or cytoplasmic compartment. TRAF6, in turn, activates SAPK/JNK and p38 MAPK phosphorylation, which in turn stimulates IL-8 and MCP-1 production in these cells.
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PMID:CD40 ligation stimulates MCP-1 and IL-8 production, TRAF6 recruitment, and MAPK activation in proximal tubule cells. 1199 18

TRAFs (tumor necrosis factor receptor [TNFR]-associated factors) bind to the cytoplasmic portion of liganded TNFRs and stimulate activation of NF-kappaB or JNK pathways. A modulator of TRAF signaling, TANK, serves as either an enhancer or an inhibitor of TRAF-mediated signaling pathways. The crystal structure of a region of TANK bound to TRAF3 has been determined and compared to a similar CD40/TRAF3 complex. TANK and CD40 bind to the same crevice on TRAF3. The recognition motif PxQxT is presented in a boomerang-like structure in TANK that is markedly different from the hairpin loop that forms in CD40 upon binding to TRAF3. Critical TANK contact residues were confirmed by mutagenesis to be required for binding to TRAF3 or TRAF2. Binding affinity, measured by isothermal titration calorimetry and competition assays, demonstrated that TANK competes with CD40 for the TRAF binding site.
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PMID:Downstream regulator TANK binds to the CD40 recognition site on TRAF3. 1200 38

The present study investigates the effects of CD40 ligand (CD40L) on mitogenic signalling, proliferation, and migration of cultured bovine coronary artery smooth muscle cells (SMC). A time- and concentration-dependent phosphorylation of the extracellular signal-regulated kinases-1/2 (ERK-1/2) and the mitogen-activated protein kinase p38 (p38-MAPK) was observed upon stimulation with soluble CD40L (sCD40L). This phosphorylation was inhibited by neutralizing antibodies against the CD40 and CD40L, respectively. Activation of the phosphatidylinositol-3-phosphate (PI-3) kinase pathway by sCD40L, as determined by the measurement of Akt phosphorylation, was not detected. However, there was evidence for direct activation of the NFkappaB system (degradation of IkappaBalpha and nuclear translocation of the p65 NFkappaB subunit) by sCD40L. Accordingly, sCD40L caused a small but significant increase in DNA synthesis. However, sCD40L-induced DNA synthesis was not followed by proliferation (increase in cell number). Furthermore, sCD40L did not potentiate SMC mitogenesis induced by known mitogens such as platelet-derived growth factor-BB, thrombin or serum. The lack of cell proliferation was not caused by a concomitant induction of SMC apoptosis by sCD40L. The possible role of membrane-bound CD40L in SMC mitogenesis was also studied using different membrane preparations (platelets, lymphocytes). However, no mitogenic effects of membrane-bound CD40L were detected. Finally, sCD40L did not induce SMC migration. From these data it is concluded that CD40L activates mitogenic signalling and DNA synthesis but does not contribute to proliferation or migration of vascular SMC.
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PMID:CD40 ligand (CD40L) does not stimulate proliferation of vascular smooth muscle cells. 1201 89

The mechanism of proinflammatory activation of human monocytes by plasmin is unknown. Here we demonstrate that in human primary monocytes, plasmin stimulates mitogen-activated protein kinase (MAPK) signaling via phosphorylation of MAPK kinase 3/6 (MKK3/6) and p38 MAPK that triggers subsequent DNA binding of transcription factor activator protein-1 (AP-1). The AP-1 complex contained phosphorylated c-Jun and ATF2, and its DNA binding activity was blocked by the p38 MAPK inhibitor SB203580. In addition, plasmin elicits Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling, as detected by phosphorylation of JAK1 tyrosine kinase and STAT1 and STAT3 proteins. Plasmin-induced DNA binding of STAT1 and STAT3 was blocked by SB203580 and AG490, inhibitors of p38 MAPK and JAK, respectively, but not by U0126, an inhibitor of MKK1/2. DNA binding of NF-kappaB remained unaffected by any of these inhibitors. The plasmin-induced signaling led to expression of monocyte chemoattractant protein-1 (MCP-1) and CD40, which required activation of both p38 MAPK and JAK/STAT signaling pathways. Additionally, signaling through both p38 MAPK and JAK is involved in the plasmin-mediated monocyte migration, whereas the formylmethionylleucylphenylalanine-induced chemotaxis remained unaffected. Taken together, our data demonstrate a novel function of the serine protease plasmin in a proinflammatory signaling network.
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PMID:The serine protease plasmin triggers expression of MCP-1 and CD40 in human primary monocytes via activation of p38 MAPK and janus kinase (JAK)/STAT signaling pathways. 1209 96

X-linked agammaglobulinemia (XLA) is caused by mutations in the gene encoding the cytoplasmic Bruton's tyrosine kinase (Btk). Btk has been shown to play an essential role in the development of B1 (CD5+) and conventional circulating mature B cells (B2) in mouse and man. It has been shown in earlier studies that Btk is involved in both the BCR- and CD40-mediated signaling pathways. In this study, we analyzed the responsiveness of Epstein-Barr virus (EBV) transformed B cells from nine XLA patients to CD40 stimulation, particularly the CD40 induced activation of c-Jun N-terminal kinase (JNK). In eight XLA patients the JNK activation was unimpaired and in one case INK could not be activated by anti-CD40 stimulation. Btk protein expression was detectable by Western blotting in six cases, in one case Btk expression was drastically reduced, and in three cases no Btk expression could be observed. Btk kinase activity was found in three cases and it was reduced in one and not detectable in five cases. Furthermore, in one female patient with an agammaglobulinemia, Btk expression and function as well as JNK activation by CD40 stimulation was unimpaired. Our findings demonstrate that INK activation via the CD40 signaling pathway is intact in EBV-transformed B cells of most if not all XLA patients, independent of the mutation and its effect on Btk expression and kinase activity. We suggest that Btk is not necessary for the activation of INK upon CD40 stimulation, at least in the B cell subpopulation we had studied. We cannot exclude that these B cells belong to a "leaky" B-cell subpopulation in which the CD40 signaling pathway has become independent of Btk function.
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PMID:Unimpaired activation of c-Jun NH2-terminal kinase (JNK) 1 upon CD40 stimulation in B cells of patients with X-linked agammaglobulinemia. 1214 99


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