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:2.7.11.24 (mitogen-activated protein kinase)
95,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Apoptosis is a highly regulated process of cell suicide that occurs during development, host defense, and pathophysiology. The transcription factor IFN regulatory factor 5 (IRF5), known to be involved in the activation of innate immune responses, recently has been shown to be critical for DNA damage-induced apoptosis and tumor suppression. Here, we report on a cell-type-specific role of IRF5 in promoting apoptosis upon signaling through the death receptor Fas (CD95/APO-1/TNFRSF6). In particular, we show that mice deficient in the Irf5 gene are resistant to hepatic apoptosis and lethality in response to the in vivo administration of a Fas-activating monoclonal antibody, and that IRF5 is involved in a stage of Fas signaling that precedes the activation of caspase 8 and c-Jun N-terminal kinase (JNK). In addition to hepatocytes, IRF5 is also required for apoptosis in dendritic cells activated by hypomethylated CpG but not in thymocytes and embryonic fibroblasts in vitro. Thus, these findings reveal a cell-type-specific function for IRF5 in the complex regulatory mechanism of death-receptor-induced apoptosis.
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PMID:A cell-type-specific requirement for IFN regulatory factor 5 (IRF5) in Fas-induced apoptosis. 1826 44

The death receptors tumour-necrosis factor receptor-1 (TNFR1) and CD95 (also known as FAS and APO-1) transduce signals that promote cell death by apoptosis. However, these receptors are also capable of inducing anti-apoptotic signals through the activation of the transcription factor nuclear factor-kappaB (NF-kappaB) or through activation of the proliferative mitogen-activated protein kinase (MAPK) cascade. Recent findings reveal a role for receptor internalization and endosomal trafficking in selectively transmitting the signals that lead either to apoptosis or to the survival of the cell.
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PMID:Regulation of TNFR1 and CD95 signalling by receptor compartmentalization. 1854 70

Prior studies have noted that inhibitors of mitogen-activated protein kinase (MAPK) kinase 1/2 (MEK1/2) enhanced geldanamycin lethality in malignant hematopoietic cells by promoting mitochondrial dysfunction. The present studies focused on defining the mechanism(s) by which these agents altered survival in carcinoma cells. MEK1/2 inhibitors [PD184352; AZD6244 (ARRY-142886)] interacted in a synergistic manner with geldanamycins [17-allylamino-17-demethoxygeldanamycin (17AAG) and 17-dimethylaminoethylamino-17-demethoxy-geldanamycin] to kill hepatoma and pancreatic carcinoma cells that correlated with inactivation of extracellular signal-regulated kinase 1/2 and AKT and with activation of p38 MAPK; p38 MAPK activation was reactive oxygen species dependent. Treatment of cells with MEK1/2 inhibitors and 17AAG reduced expression of c-FLIP-s that was mechanistically connected to loss of MEK1/2 and AKT function; inhibition of caspase-8 or overexpression of c-FLIP-s abolished cell killing by MEK1/2 inhibitors and 17AAG. Treatment of cells with MEK1/2 inhibitors and 17AAG caused a p38 MAPK-dependent plasma membrane clustering of CD95 without altering the levels or cleavage of FAS ligand. In parallel, treatment of cells with MEK1/2 inhibitors and 17AAG caused a p38 MAPK-dependent association of caspase-8 with CD95. Inhibition of p38 MAPK or knockdown of BID, FAS-associated death domain, or CD95 expression suppressed MEK1/2 inhibitor and 17AAG lethality. Similar correlative data were obtained using a xenograft flank tumor model system. Our data show that treatment of tumor cells with MEK1/2 inhibitors and 17AAG induces activation of the extrinsic pathway and that suppression of c-FLIP-s expression is [Mol Cancer Ther 2008;7(9):2633-48].
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PMID:Mitogen-activated protein kinase kinase 1/2 inhibitors and 17-allylamino-17-demethoxygeldanamycin synergize to kill human gastrointestinal tumor cells in vitro via suppression of c-FLIP-s levels and activation of CD95. 1879 Jul 46

RIP2/RICK/CARDIAK is a member of the receptor interacting protein kinase (RIP) family. RIP2 promotes NF-kappaB activation as well as activation of the MAPKs JNK, ERK1/2 and p38 MAPK, thereby playing an emergent role in the innate immune response and NOD signaling. Moreover, RIP2 has been shown to interact with the CARD of caspase-1 and to induce IL-1beta maturation as well as in the induction of CD95-mediated programmed cell death by enhancing caspase-8 activity. Here, we report the identification and characterization of a novel alternative mRNA splice variant of RIP2, encoding a protein designated RIP2-beta, comprised of only a portion of the N-terminal kinase domain and lacking the intermediate region and C-terminal CARD. As revealed by gene transfer experiments, these structural changes in RIP2-beta are associated with a loss of activation with respect to NF-kappaB and MAPK activation, IL-1beta secretion, and caspase-8-mediated apoptosis. In conclusion, alternative mRNA splicing may be involved in the regulation of RIP2 actions, underlying the complexity of RIP2-dependent pathways regulating stress signaling and apoptosis.
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PMID:RIP2-beta: a novel alternative mRNA splice variant of the receptor interacting protein kinase RIP2. 1912 70

Internalization of cell surface receptors has long been regarded as a pure means to terminate signaling via receptor degradation. A growing body of information points to the fact that many internalized receptors are still in their active state and that signaling continues along the endocytic pathway. Thus endocytosis orchestrates cell signaling by coupling and integrating different cascades on the surface of endocytic vesicles to control the quality, duration, intensity, and distribution of signaling events. The death receptors tumor necrosis factor-receptor 1 (TNF-R1) and CD95 (Fas, APO-1) are known not only to signal for cell death via apoptosis but are also capable of inducing antiapoptotic signals via transcription factor NF-kappaB induction or activation of the proliferative mitogen-activated protein kinase (MAPK)/ERK (extracellular signal-regulated kinase) protein kinase cascades, resulting in cell protection and tissue regeneration. A clue to the understanding of these contradictory biological phenomena may arise from recent findings which reveal a regulatory role of receptor internalization and intracellular receptor trafficking in selectively transmitting signals, which lead either to apoptosis or to the survival of the cell. In this chapter, we discuss the dichotomy of pro- and antiapoptotic signaling of the death receptors TNF-R1 and CD95. First, we will address the role of lipid rafts and post-translational modifications of death receptors in regulating the formation of receptor complexes. Then, we will discuss the role of internalization in determining the fate of the receptors and subsequently the specificity of signaling events. We propose that fusion of internalized TNF-receptosomes with trans-Golgi vesicles should be recognized as a novel mechanism to transduce death signals along the endocytic route. Finally, the lessons learnt from the strategy of adenovirus to escape apoptosis by targeting death receptor internalization demonstrate the biological significance of TNF receptor compartmentalization for immunosurveillance.
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PMID:Impact of TNF-R1 and CD95 internalization on apoptotic and antiapoptotic signaling. 1913 22

Apoptosis or programmed cell-death is an important process involved in tissue homeostasis, development and a variety of immune responses.(1) The apoptotic program can be activated via transmembrane receptors stimulated by their cognate ligands. The presence of a well-conserved region of 80 amino acids in their intracellular tail, the Death-Domain (DD), has conferred those receptors the general name of "death receptors". Death receptors are a subfamily of the TNF receptor superfamily, which includes the TNF receptor-I (TNFR1), TRAMP, DR3/APO-3, TRAIL-receptor 1 (TRAIL-R1/DR4), TRAIL-receptor 2 (TRAIL-R1/DR5), DR6 and CD95 (Fas/Apo-1). The pro-apoptotic properties of the CD95 system have been extensively studied during the past decades. Nevertheless, CD95 has now emerged as an important activator of other major signaling pathways leading to a variety of phenotypes. In the last years, stimulation of CD95 has been described to activate the MAPK pathways p38, JNK and ERK. (2-6) CD95 has also been shown to activate the transcription factor NFkB. (67-9) However, the molecular mechanisms leading to activation of such pathways are not fully understood and their contribution to the final phenotype is still unclear. CD95 has been shown to be particularly involved in tumor cell invasion, (6) neurite sprouting and outgrowth,(5,10) as well as cell proliferation(11,12)--functions that lay to rest the general assumption of CD95 as a death receptor. In our group we have recently described a novel molecular link between CD95 and the phosphatydilinositol-3-kinase (PI3K) pathway in Glioblastoma multiforme. In the present review we will discuss the past and present knowledge of the CD95/CD95L system and its role in PI3K signaling.
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PMID:Tyrosine phosphorylation and CD95: a FAScinating switch. 1922 5

Melanoma differentiation associated gene-7/interleukin-24 (mda-7/IL-24) is a novel cytokine displaying selective apoptosis-inducing activity in transformed cells without harming normal cells. The present studies focused on clarifying the mechanism(s) by which glutathione S-transferase (GST)-MDA-7 altered cell survival of human renal carcinoma cells in vitro. GST-MDA-7 caused plasma membrane clustering of CD95 and the association of CD95 with procaspase-8. GST-MDA-7 lethality was suppressed by inhibition of caspase-8 or by overexpression of short-form cellular FLICE inhibitory protein, but only weakly by inhibition of cathepsin proteases. GST-MDA-7-induced CD95 clustering (and apoptosis) was blocked by knockdown of acidic sphingomyelinase or, to a greater extent, ceramide synthase-6 expression. GST-MDA-7 killing was, in parallel, dependent on inactivation of extracellular signal-regulated kinase 1/2 and on CD95-induced p38 mitogen-activated protein kinase and c-jun NH(2)-terminal kinase-1/2 signaling. Knockdown of CD95 expression abolished GST-MDA-7-induced phosphorylation of protein kinase R-like endoplasmic reticulum kinase. GST-MDA-7 lethality was suppressed by knockout or expression of a dominant negative protein kinase R-like endoplasmic reticulum kinase that correlated with reduced c-jun NH(2)-terminal kinase-1/2 and p38 mitogen-activated protein kinase signaling and maintained extracellular signal-regulated kinase-1/2 phosphorylation. GST-MDA-7 caused vacuolization of LC3 through a mechanism that was largely CD95 dependent and whose formation was suppressed by knockdown of ATG5 expression. Knockdown of ATG5 suppressed GST-MDA-7 toxicity. Our data show that in kidney cancer cells GST-MDA-7 induces ceramide-dependent activation of CD95, which is causal in promoting an endoplasmic reticulum stress response that activates multiple proapoptotic pathways to decrease survival.
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PMID:MDA-7/IL-24-induced cell killing in malignant renal carcinoma cells occurs by a ceramide/CD95/PERK-dependent mechanism. 1941 61

Bile acids have been reported to induce epidermal growth factor receptor (EGFR) activation and subsequent proliferation of activated hepatic stellate cells (HSC), but the underlying mechanisms and whether quiescent HSC are also a target for bile acid-induced proliferation or apoptosis remained unclear. Therefore, primary rat HSC were cultured for up to 48 h and analyzed for their proliferative/apoptotic responses toward bile acids. Hydrophobic bile acids, i.e. taurolithocholate 3-sulfate, taurochenodeoxycholate, and glycochenodeoxycholate, but not taurocholate or tauroursodeoxycholate, induced Yes-dependent EGFR phosphorylation. Simultaneously, hydrophobic bile acids induced phosphorylation of the NADPH oxidase subunit p47(phox) and formation of reactive oxygen species (ROS). ROS production was sensitive to inhibition of acidic sphingomyelinase, protein kinase Czeta, and NADPH oxidases. All maneuvers which prevented bile acid-induced ROS formation also prevented Yes and subsequent EGFR phosphorylation. Taurolithocholate 3-sulfate-induced EGFR activation was followed by extracellular signal-regulated kinase 1/2, but not c-Jun N-terminal kinase (JNK) activation, and stimulated HSC proliferation. When, however, a JNK signal was induced by coadministration of cycloheximide or hydrogen peroxide (H2O2), activated EGFR associated with CD95 and triggered EGFR-mediated CD95-tyrosine phosphorylation and subsequent formation of the death-inducing signaling complex. In conclusion, hydrophobic bile acids lead to a NADPH oxidase-driven ROS generation followed by a Yes-mediated EGFR activation in quiescent primary rat HSC. This proliferative signal shifts to an apoptotic signal when a JNK signal simultaneously comes into play.
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PMID:Bile acid-induced epidermal growth factor receptor activation in quiescent rat hepatic stellate cells can trigger both proliferation and apoptosis. 1955 64

A blockade of CD44 can interfere with haematopoietic and leukemic stem cell homing, the latter being considered as a therapeutic option in haematological malignancies. We here aimed to explore the molecular mechanism underlying the therapeutic efficacy of anti-CD44. We noted that in irradiated mice reconstituted with a bone marrow cell transplant, anti-CD44 exerts a stronger effect on haematopoietic reconstitution than on T lymphoma (EL4) growth. Nonetheless, in the non-reconstituted mouse anti-CD44 suffices for a prolonged survival of EL4-bearing mice, where anti-CD44-prohibited homing actively drives EL4 cells into apoptosis. In vitro, a CD44 occupancy results in a 2-4-fold increase in apoptotic EL4 cells. Death receptor expression (CD95, TRAIL, TNFRI) remains unaltered and CD95 cross-linking-mediated apoptosis is not affected. Instead, CD44 ligation promotes mitochondrial depolarization that is accompanied by caspase-9 cleavage and is inhibited in the presence of a caspase-9 inhibitor. Apoptosis becomes initiated by activation of CD44-associated phosphatase 2A (PP2A) and proceeds via ERK1/2 dephosphorylation without ERK1/2 degradation. Accordingly, CD44-induced apoptosis could be mimicked by ERK1/2 inhibition, that also promotes EL4 cell apoptosis through the mitochondrial pathway. Thus, during haematopoietic stem cell reconstitution care should be taken not to interfere by a blockade of CD44 with haematopoiesis, which could be circumvented by selectively targeting leukemic CD44 isoforms. Beyond homing/settlement in the bone marrow niche, anti-CD44 drives leukemic T cells into apoptosis via the mitochondrial death pathway by CD44 associating with PP2A. Uncovering this new pathway of CD44-induced leukemic cell death provides new options of therapeutic interference.
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PMID:Anti-CD44 induces apoptosis in T lymphoma via mitochondrial depolarization. 1976 70

Fas (CD95/APO-1) is a cell surface "death receptor" that mediates apoptosis upon engagement by its ligand, FasL. Paradoxically, Fas/FasL can also promote cell invasion among non-apoptotic cells; here, we show that Fas/FasL signaling can promote tumor invasion when apoptosis is compromised. We have developed a recombinant FasL Interfering Protein (FIP) to interfere with Fas signaling in C6 glioma cells expressing both Fas receptor and its ligand. FIP administration did not affect cell viability but impaired cell motility and invasiveness of glioma cells. Blockade of Fas signaling reduced MMP-2 activity in glioma cells, that was associated with down-regulation of MAPK signaling, and AP-1 and NFkappaB-driven transcription. FIP treatment did not affect mmp-2 and mt1-mmp expression but significantly attenuated timp-2 expression and TIMP-2 amount in the culture medium. Studies with pharmacological inhibitors of JNK/c-Jun (SP600125) and NFkappaB (BAY11-7082) signaling pathways demonstrated that timp-2 expression is regulated by NFkappaB transcription factor. Our findings show that non-apoptotic Fas signaling activated in the autocrine manner or through microenvironment derived factors can regulate invasiveness of glioma cells via modulation of MMP-2 activation, likely by controlling TIMP-2 expression.
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PMID:Non-apoptotic Fas signaling regulates invasiveness of glioma cells and modulates MMP-2 activity via NFkappaB-TIMP-2 pathway. 1978 21


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