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)

Extracellular proteases that are expressed in primary and secondary foci of viral infection are potentially important mediators of infectious inflammatory processes. For some viruses, such as influenza virus and rotaviruses, proteases such as trypsin enhance infectivity by a direct proteolytic effect on some virion proteins. By using an in vitro model of herpesvirus infection, the possibility that proteases modulate the viral cycle through signalling delivered to the infected cell was investigated. It is reported that exposure of pseudorabies virus-infected cells to trypsin increased virus production. Moreover, this treatment induced synergistic and sustained activation of the extracellular signal-regulated kinase (ERK) 1/2 signalling pathway, which appeared to be necessary for this increased viral production. These results suggest that herpesviruses could take advantage of the inflammatory context and particularly of the presence of proteases to increase their replication. Thus, these data point to a potentially important role of extracellular proteases in herpesvirus infection.
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PMID:Trypsin increases pseudorabies virus production through activation of the ERK signalling pathway. 1660 10

Replication and transcription of the influenza virus genome takes place exclusively within the nucleus of the infected cells. The viral RNA genome, polymerase subunits, and nucleoprotein form ribonucleoprotein (RNP) complexes. Late in the infectious cycle RNPs have to be exported from the nucleus to be enwrapped into budding progeny virions at the cell membrane. This process requires viral activation of the cellular Raf/MEK/ERK (mitogen-activated protein kinase (MAPK)) signaling cascade that is activated late in the infection cycle. Accordingly, block of the cascade results in retardation of RNP export and reduced titers of progeny virus. In the present study we have analyzed the importance of cell-membrane association of the viral hemagglutinin glycoprotein for viral MAPK activation. We show that hemagglutinin membrane accumulation and its tight association with lipid-raft domains trigger activation of the MAPK cascade via protein kinase Calpha activation and induces RNP export. This may represent an auto-regulative mechanism that coordinates timing of RNP export to a point when all viral components are ready for virus budding.
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PMID:Membrane accumulation of influenza A virus hemagglutinin triggers nuclear export of the viral genome via protein kinase Calpha-mediated activation of ERK signaling. 1660 52

Mitogen-activated protein (MAP) kinase cascades are multifunctional signalling networks that influence cell growth, differentiation, apoptosis and cellular responses to stress. Apoptosis signal-regulating kinase 1 (ASK1) is a MAP kinase kinase kinase that triggers apoptogenic kinase cascade leading to the phosphorylation/activation of c-Jun N-terminal kinases (JNK) and p38-MAP kinase, which are responsible to induce apoptotic cell death. This pathway plays a pivotal role in the transduction of signals from different apoptotic stimuli. Recently, it has become evident that ASK1 and its downstream pathway are employed in the transduction of signals from Toll-like receptors (TLR) - multistep processes that interfere with different intracellular signalling pathways. TLR are the key proteins that allow mammals to detect pathogens and mediate innate immune responses. In addition, ASK1 and its downstream pathway play a target role in the regulation of apoptosis in some cases of viral infection - AIDS, influenza, hepatitis C and others. In the present review, we summarize current knowledge about the role of ASK1 and its downstream pathway in innate immune responses and viral infection.
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PMID:Role of MAP kinase-dependent apoptotic pathway in innate immune responses and viral infection. 1676 92

We used cDNA microarrays to identify differentially expressed genes in mice in response to infections with influenza virus A/PR/8/34 (H1N1) and Streptococcus pneumoniae. Expression microarray analysis showed up-regulation and down-regulation of many genes involved in the defense, inflammatory response and intracellular signaling pathways including chemokine, apoptosis, MAPK, Notch, Jak-STAT, T-cell receptor and complement and coagulation cascades. We have revealed signature patterns of gene expression in mice infected with two different classes of pathogens: influenza virus A and S. pneumoniae. Quantitative real-time RT-PCR results confirmed microarray results for most of the genes tested. These studies document clear differences in gene expression profiles between mice infected with influenza virus A and S. pneumoniae. Identification of genes that are differentially expressed after respiratory infections can provide insights into the mechanisms by which the host interacts with different pathogens, useful information about stage of diseases and selection of suitable targets for early diagnosis and treatments. The advantage of this novel approach is that the detection of pathogens is based on the differences in host gene expression profiles in response to different pathogens instead of detecting pathogens directly.
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PMID:Signature patterns revealed by microarray analyses of mice infected with influenza virus A and Streptococcus pneumoniae. 1679 4

Angelica dahurica (Umbelliferae) has been used to treat headache of common cold, supraorbital neuralgia, painful swelling on the body, nasal stuffiness, leukorrhea and arthralgia due to wind-dampness in Korean traditional medicine. It is also claimed to be effective in the treatment of acne, erythema, headache, toothache, sinusitis, colds and flu. The present study focused whether the ethyl acetate extract from Angelica Dahuricae Radix (EAAD) inhibits production of nitric oxide (NO), prostaglandin E(2) (PGE(2)) and tumor necrosis factor (TNF)-alpha, as well as expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), nuclear factor-kappaB (NF-kappaB) and mitogen-activated protein kinases (MAPKs) in lipopolysaccharide (LPS)-stimulated macrophages. EAAD inhibited LPS-induced NO, PGE(2) and TNF-alpha production as well as expression of iNOS and COX-2 in RAW 264.7 cells. EAAD inhibited LPS-induced TNF-alpha production in THP-1 cells. Furthermore, EAAD suppressed LPS-induced phosphorylation of p38 MAPK and extracellular-signal regulated kinases 1/2 (ERK1/2), I-kappaBalpha degradation, and NF-kappaB activation in RAW 264.7 cells. These results suggest that EAAD has the inhibitory effects on LPS-induced TNF-alpha, NO and PGE(2) production, and expression of iNOS and COX-2 in macrophage through blockade in the phosphorylation of MAPKs, following I-kappaBalpha degradation and NF-kappaB activation.
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PMID:Ethyl acetate extract from Angelica Dahuricae Radix inhibits lipopolysaccharide-induced production of nitric oxide, prostaglandin E2 and tumor necrosis factor-alphavia mitogen-activated protein kinases and nuclear factor-kappaB in macrophages. 1722 75

GRASP-1 is a neuronally enriched protein that interacts with the AMPA-type glutamate receptor/GRIP complex. GRASP-1 can be cleaved by Caspase-3 in both normal and ischemic brains although the functional significance of this cleavage remains elusive. We investigated signal transduction pathways that might lie downstream of GRASP-1 and found that GRASP-1 potently activates JNK pathway signaling, with no effect on ERK signaling. Such JNK pathway activating activity requires binding of GRASP-1 to both JNK and the upstream JNK pathway activator MEKK-1. Furthermore, mutations that prevent Caspase 3-cleavage of GRASP-1 dramatically inhibit the JNK pathway activating activity of GRASP-1, suggesting a novel link between Caspase-3 activation and JNK pathway signaling. These results suggest that GRASP-1 serves as a scaffold protein to facilitate MEKK-1 activation of JNK signaling in neurons.
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PMID:GRASP-1 is a neuronal scaffold protein for the JNK signaling pathway. 1776 Nov 73

Toll-like receptors (TLRs) recognise specific molecular signatures of pathogens and trigger antimicrobial defence responses. Thereby, two independent signalling pathways can be distinguished: The inflammatory signalling pathway acting via the adapter molecule MyD88, leading to the activation of nuclear factor-kappaB (NF-kappaB) and mitogen activated protein kinases (MAPK) such as SAPK/JNK and p38 MAPK and the interferon (IFN) dependent pathway that signals via TRIF and results in the production of IFN-alpha/beta. Several evolutionarily conserved molecular patterns are expressed by pathogens, leading to the question if concerted targeting of different TLRs may induce exaggerated immune responses by signalling via both TLR pathways. Here we report that monocyte-derived dendritic cells (MoDCs) combine and integrate signals received via the IFN-dependent pathway by engagement of TLR3 (poly I:C) and activation of TRIF with the MyD88-dependent pathway by ligation of TLR2 (PGN), TLR2/TLR6 (zymosan) and TLR5 (flagellin). The generally low IL-12p70 inducers resulted in combination of both pathways in cytokine levels similar to LPS, which acts via TLR4 and induces recruitment of MyD88/Tirap and TRIF/TRAM adapter proteins. The combination of TLR3 (poly I:C) or TLR4 (LPS) engagement with TLR8 (R848) ligation induced synergistic effects on cytokine production with a boost especially in IL-12p70 secretion. SB203580, a specific p38 MAPK inhibitor, completely blocked TLR ligand mediated IL-12p70 secretion, whereby specific inhibitors for SAPK/JNK (SP600125) and NF-kappaB (PDTC) only repressed partially the IL-12p70 secretion. Enhanced phosphorylation in poly I:C and R848 activated MoDCs revealed the critical contribution of p38 MAPK in synergistically induced IL-12p70 induction. Further investigation of primary and recall CD8+ T cell responses to the MUC(12-20) M1.2 peptide LLLLTVLTV and the influenza A virus matrix(58-66) peptide GILGFVFTL proved that synergistically activated MoDCs were superior compared with LPS or R848 alone. The results indicate that dendritic cells process, combine and integrate signals delivered by pathogens to launch effective adaptive immune responses.
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PMID:Synergism of Toll-like receptor-induced interleukin-12p70 secretion by monocyte-derived dendritic cells is mediated through p38 MAPK and lowers the threshold of T-helper cell type 1 responses. 1792 69

There is growing evidence that plasmacytoid dendritic cells (pDC) are involved in the innate recognition of various microbes. However, the precise consequences of pathogen recognition on pDC activation and function are incompletely understood. Using a novel transgenic mouse model that facilitates the isolation of highly pure pDC populations, we found that influenza virus PR/8, a TLR7 ligand, and CpG 1826 oligonucleotide, a TLR9 ligand, induced surprisingly divergent activation programs in these cells. pDC stimulated with PR/8 produced large amounts of type I IFNs, and CpG 1826-stimulated pDC expressed higher levels of costimulatory molecules and proinflammatory cytokines and induced stronger proliferation of T cells. Transcriptome analysis uncovered the differential regulation in pDC of 178 and 1577 genes by PR/8 and CpG 1826, respectively. These differences may relate to the activation of discrete signaling pathways, as evidenced by distinct ERK1/2 and p38 MAPK phosphorylation kinetics. Finally, pDC isolated ex vivo during PR/8 infection or after i.v. CpG 1826 injection resembled their in vitro counterparts, corroborating that these cells can adopt specialized phenotypes in vivo. Thus, pDC display remarkable functional flexibility, which emphasizes their versatile functions in antimicrobial immunity and inflammatory processes.
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PMID:Two distinct activation states of plasmacytoid dendritic cells induced by influenza virus and CpG 1826 oligonucleotide. 1802 97

Influenza viruses replicate within the nucleus of infected cells. Viral genomic RNA, three polymerase subunits (PB2, PB1, and PA), and the nucleoprotein (NP) form ribonucleoprotein complexes (RNPs) that are exported from the nucleus late during the infectious cycle. The virus-induced Raf/MEK/ERK (MAPK) signal cascade is crucial for efficient virus replication. Blockade of this pathway retards RNP export and reduces virus titers. Hemagglutinin (HA) accumulation and its tight association with lipid rafts activate ERK and enhance localization of cytoplasmic RNPs. We studied the induction of MAPK signal cascade by two seasonal human influenza A viruses A/HK/218449/06 (H3N2) and A/HK/218847/06 (H1N1) that differed substantially in their replication efficiency in tissue culture. Infection with H3N2 virus, which replicates efficiently, resulted in higher HA expression and its accumulation on the cell membrane, leading to substantially increased activation of MAPK signaling compared to that caused by H1N1 subtype. More H3N2-HAs were expressed and accumulated on the cell membrane than did H1N1-HAs. Viral polymerase genes, particularly H3N2-PB1 and H3N2-PB2, were observed to contribute to increased viral polymerase activity. Applying plasmid-based reverse genetics to analyze the role of PB1 protein in activating HA-induced MAPK cascade showed that recombinant H1N1 virus possessing the H3N2-PB1 (rgH1N1/H3N2-PB1) induced greater ERK activation, resulting in increased nuclear export of the viral genome and higr virus titers. We conclude that enhanced viral polymerase activity promotes the replication and transcription of viral RNA leading to increased accumulation of HA on the cell surface and thereby resulting in an upregulation of the MAPK cascade and more efficient nuclear RNP-export as well as virus production.
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PMID:Higher polymerase activity of a human influenza virus enhances activation of the hemagglutinin-induced Raf/MEK/ERK signal cascade. 1805 52

Lactoferrin (LF) is an important protein component of the innate immune system that is broadly distributed within the body fluids. LF is endowed with multiple biological activities. Talactoferrin (TLF), a recombinant human LF, is in clinical development as an anticancer agent and is entering Phase III clinical trials. Here, we show that TLF induces the maturation of human dendritic cells (DCs) derived from monocytes. TLF, at physiologically relevant concentrations (100 microg/ml) up-regulates the expression of human leukocyte antigen (HLA) class II, CD83, CD80, and CD86 costimulatory molecule and CXCR4 and CCR7 chemokine receptors, acting primarily through the p38 MAPK signaling pathway. DCs matured by TLF displayed an enhanced release of IL-8 and CXCL10, as well as a significantly reduced production of IL-6, IL-10, and CCL20. They also display a reduced ability to take up antigen and increased capacity to trigger proliferation and release IFN-gamma in the presence of allogeneic human T cells. TLF-matured DCs are able to prime naive T cells to respond to KLH antigen and display a significantly increased capacity to present Flu-MA(58-66) peptide to HLA-A2-matched T cells. These data suggest that a key immunomodulatory function that may be mediated by TLF is to link the innate with adaptive immunity through DC maturation.
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PMID:Lactoferrin, a major defense protein of innate immunity, is a novel maturation factor for human dendritic cells. 1836 98


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