Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mast cells are involved in many disorders where the triggering mechanism that leads to degranulation and/or cytokine secretion has not been defined. Several chronic inflammatory diseases are associated with increased mast cell numbers and upregulation of the TNF receptor family member CD30, but the role of elevated CD30 expression is poorly understood. Here we report what we believe to be a novel way to activate mast cells with CD30 that leads to degranulation-independent secretion of chemokines. CD30 induced a de novo synthesis and secretion of the chemokines IL-8, macrophage inflammatory protein-1alpha (MIP-1alpha), and MIP-1beta, a process involving the MAPK/ERK pathway. Mast cells were found to be the predominant CD30 ligand-positive (CD30L-positive) cell in the chronic inflammatory skin diseases psoriasis and atopic dermatitis, and both CD30 and CD30L expression were upregulated in lesional skin in these conditions. Furthermore, the number of IL-8-positive mast cells was elevated both in psoriatic and atopic dermatitis lesional skin as well as in ex vivo CD30-treated healthy skin organ cultures. In summary, characterization of CD30 activation of mast cells has uncovered an IgE-independent pathway that is of importance in understanding the entirety of the role of mast cells in diseases associated with mast cells and CD30 expression. These diseases include Hodgkin lymphoma, atopic dermatitis, and psoriasis.
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PMID:Mast cell CD30 ligand is upregulated in cutaneous inflammation and mediates degranulation-independent chemokine secretion. 1696 9

Pneumocystis carinii is an opportunistic fungal pathogen that causes pneumonia (PCP) in immunocompromised individuals. Recent studies have demonstrated that the host's immune response is clearly responsible for the majority of the pathophysiological changes associated with PCP. P. carinii interacts closely with alveolar epithelial cells (AECs); however, the nature and pathological consequences of the epithelial response remain poorly defined. Monocyte chemotactic protein-1 (MCP-1) is involved in lung inflammation, immunity, and epithelial repair and is upregulated during PCP. To determine whether AECs are an important source of MCP-1 in the P. carinii-infected lung, in vivo and in vitro studies were performed. In situ hybridization showed that MCP-1 mRNA was localized to cells with morphological characteristics of AECs in the lungs of infected mice. In vitro studies demonstrated that P. carinii stimulated a time- and dose-dependent MCP-1 response in primary murine type II cells that was preceded by JNK activation. Pharmacological inhibition of JNK nearly abolished P. carinii-stimulated MCP-1 production, while ERK, p38 MAPK, and TNF receptor signaling were not required. Furthermore, delivery of a JNK inhibitory peptide specifically to pulmonary epithelial cells using a recombinant adenovirus vector blocked the early lung MCP-1 response following intratracheal instillation of infectious P. carinii. JNK inhibition did not affect P. carinii-stimulated production of macrophage inflammatory protein-2 in vitro or in vivo, indicating that multiple signaling pathways are activated in P. carinii-stimulated AECs. These data demonstrate that AECs respond to P. carinii in a proinflammatory manner that may contribute to the generation of immune-mediated lung injury.
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PMID:Pneumocystis stimulates MCP-1 production by alveolar epithelial cells through a JNK-dependent mechanism. 1730 12

The p21 RAS subfamily of small GTPases, including KRAS, HRAS, and NRAS, regulates cell proliferation, cytoskeletal organization, and other signaling networks, and is the most frequent target of activating mutations in cancer. Activating germline mutations of KRAS and HRAS cause severe developmental abnormalities leading to Noonan, cardio-facial-cutaneous, and Costello syndrome, but activating germline mutations of NRAS have not been reported. Autoimmune lymphoproliferative syndrome (ALPS) is the most common genetic disease of lymphocyte apoptosis and causes autoimmunity as well as excessive lymphocyte accumulation, particularly of CD4(-), CD8(-) alphabeta T cells. Mutations in ALPS typically affect CD95 (Fas/APO-1)-mediated apoptosis, one of the extrinsic death pathways involving TNF receptor superfamily proteins, but certain ALPS individuals have no such mutations. We show here that the salient features of ALPS as well as a predisposition to hematological malignancies can be caused by a heterozygous germline Gly13Asp activating mutation of the NRAS oncogene that does not impair CD95-mediated apoptosis. The increase in active, GTP-bound NRAS augments RAF/MEK/ERK signaling, which markedly decreases the proapoptotic protein BIM and attenuates intrinsic, nonreceptor-mediated mitochondrial apoptosis. Thus, germline activating mutations in NRAS differ from other p21 Ras oncoproteins by causing selective immune abnormalities without general developmental defects. Our observations on the effects of NRAS activation indicate that RAS-inactivating drugs, such as farnesyltransferase inhibitors should be examined in human autoimmune and lymphocyte homeostasis disorders.
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PMID:NRAS mutation causes a human autoimmune lymphoproliferative syndrome. 1751 60

Glucocorticoid-induced TNF receptor family related protein ligand (GITRL) is known to interact with its cognate receptor GITR. In order to investigate the potential role of GITRL in the pro-inflammatory activation of macrophages and the signaling pathway induced by GITRL, we stimulated the macrophage cell line, THP-1, and primary macrophages with an anti-GITRL monoclonal antibody or a GITR:Fc fusion protein and analyzed the cellular responses. The stimulation of GITRL induced the expression of pro-inflammatory cytokines and matrix metalloproteinase (MMP)-9 and up-regulated ICAM-1 expression levels, which was responsible for enhanced cellular aggregation and adhesion to extracellular matrix proteins. The activation of these pro-inflammatory mediators required the activation of ERK1/2 mitogen-activated protein kinase (MAPK) and negatively regulated by p38 MAPK and JNK. Immunofluorescence analysis detected nuclear translocation of the NF-kappaB p50 subunit and this was blocked by ERK inhibitor, indicating that GITRL stimulation induced ERK1/2 phosphorylation and subsequent activation of NF-kappaB. Furthermore, the expression of GITRL and GITR was detected in macrophages in inflammatory disease specimens such as atherosclerotic plaques and synovial tissues of rheumatoid arthritis. These observations raise the possibility that the GITRL-mediated inflammatory activation of macrophages is involved in the pathogenesis of inflammatory diseases.
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PMID:Reverse signaling initiated from GITRL induces NF-kappaB activation through ERK in the inflammatory activation of macrophages. 1760 48

Epstein-Barr virus (EBV) can infect T lymphocytes and manifests as hemophagocytic lymphohistiocytosis (HLH), a distinct entity of hemophagocytic syndrome (HPS) characterized by fever, hepatosplenomegaly, cytopenia, hypercytokinemia, and systemic macrophage activation with hemophagocytosis. In a substantial percentage of HLH patients, the disease may relapse or progress to T-cell lymphoma in months to years. In the present review, the authors summarize the previous studies on the pathogenesis of HLH and the potential mechanism for the progression of disease from HLH to T-cell lymphoma. The infection of T cells by EBV could activate T cells to secrete proinflammatory cytokines, particularly tumor necrosis factor-alpha (TNF-alpha), which subsequently activate macrophages. EBV latent membrane protein-1 (LMP-1) is the viral product responsible for the activation of the TNF receptor (TNFR) associated factors/nuclear factor-kappaB (NF-kappaB)/ERK pathway to enhance cytokine secretion mediated through the suppression of the SAP/SH2D1A gene. The activation of NF-kappaB will confer resistance to TNF-alpha-induced apoptosis on EBV-infected T cells through the down-regulation of TNFR-1. Consistent with in vitro observations, EBV-associated T or natural killer/T-cell lymphoma showed constitutive activation of NF-kappaB, explaining its drug resistance, hypercytokinemia, and poor prognosis. Therefore, similar to other inflammation-associated cancers, HLH provides a unique model to study the mechanism of disease progression from a benign virus-infected disorder (HLH) to T-cell lymphoma. Inhibition of the NF-kappaB signal pathway should provide a potential target for the treatment of HLH and EBV-associated T-cell lymphoma.
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PMID:Pathogenesis and mechanism of disease progression from hemophagocytic lymphohistiocytosis to Epstein-Barr virus-associated T-cell lymphoma: nuclear factor-kappa B pathway as a potential therapeutic target. 1762 15

The obligate intracellular human pathogenic bacterium Chlamydia trachomatis has evolved multiple mechanisms to circumvent the host immune system. Infected cells exhibit a profound resistance to the induction of apoptosis and down-regulate the expression of major histocompatibility complex class I and class II molecules to evade the cytotoxic effect of effector immune cells. Here we demonstrate the down-regulation of tumor necrosis factor receptor 1 (TNFR1) on the surface of infected cells. Interestingly, other members of the TNFR family such as TNFR2 and CD95 (Fas/Apo-1) were not modulated during infection, suggesting a selective mechanism underlying surface reduction of TNFR1. The observed effect was not due to reduced expression since the overall amount of TNFR1 protein was increased in infected cells. TNFR1 accumulated at the chlamydial inclusion and was shed by the infected cell into the culture supernatant. Receptor shedding depended on the infection-induced activation of the MEK-ERK pathway and the metalloproteinase TACE (TNFalpha converting enzyme). Our results point to a new function of TNFR1 modulation by C. trachomatis in controlling inflammatory signals during infection.
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PMID:Reduced display of tumor necrosis factor receptor I at the host cell surface supports infection with Chlamydia trachomatis. 1816 50

Decoy receptor 3 (DcR3) is a member of the TNF receptor superfamily and is up-regulated in tumors originating from a diversity of lineages. DcR3 is capable of promoting angiogenesis, inducing dendritic cell apoptosis, and modulating macrophage differentiation. Since tumor-associated macrophages (TAMs) are the major infiltrating leukocytes in most malignant tumors, we used microarray technology to investigate whether DcR3 contributes to the development of TAMs. Among the DcR3-modulated genes expressed by TAMs, those that encode proteins involved in MHC class II (MHC-II)-dependent antigen presentation were down-regulated substantially, together with the master regulator of MHC-II expression (the class II transactivator, CIITA). The ERK- and JNK-induced deacetylation of histones associated with the CIITA promoters was responsible for DcR3-mediated down-regulation of MHC-II expression. Furthermore, the expression level of DcR3 in cancer cells correlated inversely with HLA-DR levels on TAMs and with the overall survival time of pancreatic cancer patients. The role of DcR3 in the development of TAMs was further confirmed using transgenic mice overexpressing DcR3. This elucidates the molecular mechanism of impaired MHC-II-mediated antigen presentation by TAMs, and raises the possibility that subversion of TAM-induced immunosuppression via inhibition of DcR3 expression might represent a target for the design of new therapeutics.
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PMID:Epigenetic control of MHC class II expression in tumor-associated macrophages by decoy receptor 3. 1834 19

Tumor necrosis factor (TNF)-alpha activates the nuclear factor kappaB (NF-kappaB) signaling pathway. The protein synthesis inhibitor cycloheximide (CHX) and its structural derivative acetoxycycloheximide (Ac-CHX) have been recently shown to block the TNF-alpha-induced activation of NF-kappaB via ectodomain shedding of TNF receptor 1 (TNF-R1) in human lung carcinoma A549 cells. In this study, we show that ERK and p38 MAP kinase are involved in the downregulation of cell surface TNF-R1 upon exposure to Ac-CHX and the subsequent inhibition of TNF-alpha-induced NF-kappaB activation. Ac-CHX was capable of promoting the sustained activation of ERK, JNK, and p38 MAP kinase. Treatment with the MEK inhibitor U0126 and the p38 MAP kinase inhibitor SB203580, but not the JNK inhibitor SP600125, reversed the diminished expression of cell surface TNF-R1 as well as the blockade of TNF-alpha-induced IkappaBalpha degradation in Ac-CHX-treated cells. Our results indicate that Ac-CHX triggers the downregulation of cell surface TNF-R1 via the activation of ERK and p38 MAP kinase, thereby preventing activation of the NF-kappaB signaling pathway by TNF-alpha.
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PMID:ERK and p38 MAP kinase are involved in downregulation of cell surface TNF receptor 1 induced by acetoxycycloheximide. 1844 99

IL-33 has been shown to induce Th2 responses by signaling through the IL-1 receptor-related protein, ST2L. However, the signal transduction pathways activated by the ST2L have not been characterized. Here, we found that IL-33-induced monocyte chemoattractant protein (MCP)-1, MCP-3 and IL-6 expression was significantly inhibited in TNF receptor-associated Factor 6 (TRAF6)-deficient MEFs. IL-33 rapidly induced the formation of ST2L complex containing IL-1 receptor-associated kinase (IRAK), however, lack of TRAF6 abolished the recruitment of IRAK to ST2L. Consequently, p38, JNK and Nuclear factor-kappaB (NF-kappaB) activation induced by IL-33 was completely inhibited in TRAF6-deficient MEFs. On the other hand, IL-33-induced ERK activation was observed regardless of the presence of TRAF6. The introduction of TRAF6 restored the efficient activation of p38, JNK and NF-kappaB in TRAF6 deficient MEFs, resulting in the induction of MCP-1, MCP-3 and IL-6 expression. Moreover, IL-33 augmented autoubiquitination of TRAF6 and the reconstitution of TRAF6 mutant (C70A) that is defective in its ubiquitin ligase activity failed to restore IL-33-induced p38, JNK and NF-kappaB activation. Thus, these data demonstrate that TRAF6 plays a pivotal role in IL-33 signaling pathway through its ubiquitin ligase activity.
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PMID:TRAF6 is a critical signal transducer in IL-33 signaling pathway. 1860 9

Tumor necrosis factor receptor 1-associated death domain protein (TRADD) is the core adaptor recruited to TNF receptor 1 (TNFR1) upon TNFalpha stimulation. In cells from TRADD-deficient mice, TNFalpha-mediated apoptosis and TNFalpha-stimulated NF-kappaB, JNK, and ERK activation are defective. TRADD is also important for germinal center formation, DR3-mediated costimulation of T cells, and TNFalpha-mediated inflammatory responses in vivo. TRADD deficiency does not enhance IFNgamma-induced signaling. Importantly, TRADD has a novel role in TLR3 and TLR4 signaling. TRADD participates in the TLR4 complex formed upon LPS stimulation, and TRADD-deficient macrophages show impaired cytokine production in response to TLR ligands in vitro. Thus, TRADD is a multifunctional protein crucial both for TNFR1 signaling and other signaling pathways relevant to immune responses.
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PMID:Beyond tumor necrosis factor receptor: TRADD signaling in toll-like receptors. 1871 21


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