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)

Death receptors have been recently identified as a subgroup of the TNF-receptor superfamily with a predominant function in induction of apoptosis. The receptors are characterized by an intracellular region, called the death domain, which is required for the transmission of the cytotoxic signal. Currently, five different such death receptors are known including tumor necrosis factor (TNF) receptor-1, CD95 (Fas/APO-1), TNF-receptor-related apoptosis-mediated protein (TRAMP) and TNF-related apoptosis-inducing ligand (TRAIL) receptor-1 and -2. The signaling pathways by which these receptors induce apoptosis are rather similar. Ligand binding induces receptor oligomerization, followed by the recruitment of an adaptor protein to the death domain through homophilic interaction. The adaptor protein then binds a proximal caspase, thereby connecting receptor signaling to the apoptotic effector machinery. In addition, further pathways have been linked to death receptor-mediated apoptosis, such as sphingomyelinases, JNK kinases and oxidative stress. These pro-apoptotic signals are counteracted by several mechanisms which inhibit apoptosis at different levels. This review summarizes the current and rapidly expanding knowledge about the biological functions of death receptors and the mechanisms to trigger or to counteract cell death.
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PMID:Apoptosis signaling by death receptors. 968 54

Both extracellular signal-regulated kinase (ERK) and c-Jun NH2-terminal kinase (JNK) have been implicated in mediating the signaling events that precede apoptosis. We studied the activation of these kinases during apoptosis of WEHI 231 B cells. Surface IgM ligation induces apoptosis of WEHI 231 cells. This effect is augmented by simultaneous engagement of CD95 and is inhibited by costimulation with either CD40 or IL-4R. We determined that surface IgM ligation activates ERK2 to a much greater level than JNK, and that IgM-mediated ERK2 activation is enhanced by costimulation with anti-CD95. Costimulation with either IL-4 or anti-CD40 interferes with anti-IgM-stimulated ERK2 activation. Transient expression of mitogen-activated protein kinase phosphatase-1 (MKP-1) inhibits both ERK2 activation and cell death following stimulation with anti-IgM and the combination of anti-IgM plus anti-CD95. CD40 engagement alone activates JNK, but IL-4 stimulation does not. N-acetyl-L-cysteine pretreatment, which blocks CD40-mediated JNK activation, does not affect the ability of CD40 to inhibit anti-IgM-mediated ERK2 activation and apoptosis. Together, these data suggest that JNK activation is not required for CD40 inhibition of surface IgM-induced cell death and that ERK2 plays an active role in mediating anti-IgM-induced apoptosis of WEHI 231 B cells.
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PMID:Extracellular signal-regulated kinase-2, but not c-Jun NH2-terminal kinase, activation correlates with surface IgM-mediated apoptosis in the WEHI 231 B cell line. 971 25

We have investigated the activation of the p38 MAPK pathway in response to CD40 engagement in multiple B cell lines and in human tonsillar B cells to define the role of p38 MAPK in proliferation, NF-kappaB activation and gene expression. Cross-linking CD40 rapidly stimulates both p38 MAPK and its downstream effector, MAPKAPK-2. Inhibition of p38 MAPK activity in vivo with the specific cell-permeable inhibitor, SB203580, under conditions that completely prevented MAPKAPK-2 activation, strongly perturbed CD40-induced tonsillar B cell proliferation while potentiating the B cell receptor (BCR)-driven proliferative response. SB203580 also significantly reduced expression of a reporter gene driven by a minimal promoter containing four NF-kappaB elements, indicating a requirement for the p38 MAPK pathway in CD40-induced NF-kappaB activation. However, CD40-mediated NF-kappaB binding was not affected by SB203580, suggesting that NF-kappaB may not be a direct target for the CD40-induced p38 MAPK pathway. In addition, SB203580 selectively reduced CD40-induced CD54/ICAM-1 expression, whereas CD40-dependent expression of CD40 and CD95/Fas and four newly defined CD40-responsive genes cIAP2, TRAF1, TRAF4/CART and DR3 were unaffected. Our observations show that the p38 MAPK pathway is required for CD40-induced proliferation and that CD40 induces gene expression via both p38 MAPK-dependent and -independent pathways.
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PMID:p38 MAPK is required for CD40-induced gene expression and proliferation in B lymphocytes. 975 36

A novel immortalized rheumatoid fibroblast-like synoviocyte (FLS) line, MH7A, was established by stably transfecting FLS cells with SV40 T antigen gene. MH7A cells expressed SV40-specific small t and large T antigens as well as an elevated level of p53 protein. They have already reached over 150 population doublings through culture crisis, and have been growing rapidly compared with the parental FLSs. Constitutive activation of p42/p44 mitogen-activated protein (MAP) kinase was detected in MH7A cells. Serum requirements for the growth of MH7A were markedly decreased compared with those for the parental FLSs. MH7A cells were stained positively for interleukin (IL)-1R, intercellular adhesion molecule-1 (ICAM-1), CD16, CD40, CD80, and CD95. IL-1beta enhanced the production of IL-6 and stromelysin-1, and the surface expression of ICAM-1, in a manner similar to that in the parental FLSs. SB203580, a specific inhibitor of p38 MAP kinase, significantly inhibited IL-1beta-induced IL-6 and stromelysin-1 production by both parental FLSs and MH7A cells; although PD098059, an inhibitor of the p42/p44 MAP kinase pathway, did not affect it. Our results clearly indicate the usefulness of MH7A cells for investigating the regulation of rheumatoid FLSs and the IL-1 signal transduction pathway to develop future RA therapy.
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PMID:Establishment and characterization of a novel human rheumatoid fibroblast-like synoviocyte line, MH7A, immortalized with SV40 T antigen. 983 20

We report here that stress stimuli such as gamma-irradiation or the anticancer drug doxorubicin activate expression of the death-inducing ligands (DILs) CD95-L, TNF-alpha and TRAIL. Apoptosis induced by gamma-irradiation or doxorubicin engages a FADD- and caspase-dependent apoptosis pathway which is inhibited by dominant negative FADD or the caspase inhibitor zVAD. zVAD did not prevent activity of JNK/SAPKs in response to doxorubicin suggesting that JNK/SAPK activity is independent of death receptor triggering during cellular stress-induced apoptosis. In addition, JNK/SAPKs remained activated by doxorubicin in resistant cell lines in which cleavage of caspases and apoptosis was not observed. These data uncouple JNK/SAPK activation and apoptosis signaling and indicate that cellular stress-induced apoptosis involves signaling via DILs which is paralleled by activation of JNK/SAPKs. Activation of these kinases may contribute e.g., to the expression of molecules involved in apoptosis but is not sufficient for induction of the apoptosis program following cellular stress.
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PMID:JNK/SAPK activity is not sufficient for anticancer therapy-induced apoptosis involving CD95-L, TRAIL and TNF-alpha. 993 84

Ceramide is a bioactive lipid mediator that has been observed to induce apoptosis in vitro. The purpose of this study was to determine whether endogenous ceramide, generated in response to in vivo administration of tumor necrosis factor-alpha (TNF-alpha), increases apoptosis in primary rat alveolar type II epithelial cells. Intratracheal instillation of TNF-alpha (5 microgram) produced a decrease in sphingomyelin and activation of a neutral sphingomyelinase. These changes were associated with a significant increase in lung ceramide content. TNF-alpha concomitantly activated the p42/44 extracellular signal-related kinases and induced nuclear factor-kappaB activation in the lung. Hypodiploid nuclei studies revealed that intratracheal TNF-alpha did not increase type II cell apoptosis compared with that in control cells after isolation. A novel observation from separate in vitro studies demonstrated that type II cells undergo a gradual increase in apoptosis after time in culture, a process that was accelerated by exposure of cells to ultraviolet light. However, culture of cells with a cell-permeable ceramide, TNF-alpha, or a related ligand, anti-CD95, did not increase apoptosis above the control level. The results suggest that ceramide resulting from TNF-alpha activation of sphingomyelin hydrolysis might activate the mitogen-activated protein kinase and nuclear factor-kappaB pathways without increasing programmed cell death in type II cells.
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PMID:TNF-alpha increases ceramide without inducing apoptosis in alveolar type II epithelial cells. 1007 Jan 13

Fas/CD95/Apo-I has been shown to stimulate a variety of molecules including several members of the caspase family and the acidic sphingomyelinase (Martin and Green 1995; Gulbins et al, 1995). Here, we demonstrate that Fas receptor-triggered activation of the acidic sphingomyelinase, consumption of sphingomyelin, release of ceramide, and subsequent activation of JNK and p38-K are regulated by caspases. Inhibition of caspases by Ac-YVAD-chloromethylketone or transient CrmA transfection prevented stimulation of acidic sphingomyelinase, release of ceramide and activation of JNK and p38-K upon Fas-receptor crosslinking. Likewise, Fas triggered apoptosis was almost completely blocked by Ac-YVAD-chloromethylketone or CrmA mediated inhibition of caspases. The results suggest a new signalling cascade from the Fas receptor via caspases to acidic sphingomyelinase, ceramide and JNK/p38-K.
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PMID:Fas/CD95/Apo-I activates the acidic sphingomyelinase via caspases. 1020 Apr 43

We report here that JNK/SAPKs are activated by TRAIL in parallel to induction of apoptosis in human T and B cell lines. Death signaling as well as JNK/SAPK activation by TRAIL in these cells is FADD- and caspase-dependent since dominant-negative FADD or the caspase inhibitor zVAD prevented both, apoptosis and JNK/SAPK activity. JNK/SAPK activity in response to triggering of CD95 by an agonistic antibody (alphaAPO-1) was also diminished by dominant-negative FADD or zVAD. Correspondingly, a cell line resistant to alphaAPO-1-induced death exhibited crossresistance to TRAIL-induced apoptosis and did not upregulate JNK/SAPK activity in response to TRAIL or alphaAPO-1. Inhibition of JNK/SAPK activity, by stably transfecting cells with a dominant-negative JNKK-MKK4 construct, reduced apoptosis in response to TRAIL or alphaAPO-1. Therefore, activation of JNK/SAPKs by TRAIL or alphaAPO-1 occurs downstream of FADD and caspases and contributes to apoptosis in human lymphoid cell lines.
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PMID:JNK/SAPK activity contributes to TRAIL-induced apoptosis. 1020 May 59

Although the protease cascade initiated by Fas (CD95, Apo-1) is well characterized, there remains little known about how kinase pathways may impact on Fas-mediated apoptosis. We recently observed that in T lymphocytes Fas strongly induced activation of JNK (c-Jun N-terminal kinase) but not of second messengers leading to activation of ERK (extracellular regulated kinase). Additionally, Fas-mediated apoptosis was significantly inhibited with PMA, a potent activator of the ERK signaling pathway. This suggested a model whereby activation of the ERK pathway might attenuate Fas-mediated apoptosis. This was confirmed in the current study by showing that activation of MEK1, the upstream regulator of ERK, reduces Fas-mediated apoptosis, whereas inhibition of MEK1 augments apoptosis by Fas. Furthermore, Fas-mediated apoptosis of Jurkat T cells is not affected by constitutively active or dominant negative variants that modulate the JNK pathway. These results demonstrate that Fas-induced JNK activation is not required for apoptosis by Jurkat T cells, but rather is more likely secondary to cell stress during the early phases of apoptosis. This is supported by the ability of the caspase blocker zVAD to inhibit both apoptosis and JNK activation by Fas.
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PMID:MEK1 activation rescues Jurkat T cells from Fas-induced apoptosis. 1035 82

Caspase-8 is the most proximal caspase in the caspase cascade and possesses a prodomain consisting of two homologous death effector domains (DEDs). We have discovered that caspase-8 and its homologs can physically interact with tumor necrosis factor receptor-associated factor family members and activate the c-Jun N-terminal kinase (JNK, or stress-activated protein kinase) pathway. This ability resides in the DED-containing prodomain of these proteins and is independent of their role as cell death proteases. A point mutant in the first DED of caspase-8 can block JNK activation induced by several death domain receptors. Inhibition of JNK activation blocks apoptosis mediated by caspase-10, Mach-related inducer of toxicity/cFLIP, and Fas/CD95, thereby suggesting a cooperative role of this pathway in the mediation of caspase-induced apoptosis.
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PMID:Activation of the c-Jun N-terminal kinase/stress-activated protein kinase pathway by overexpression of caspase-8 and its homologs. 1038 28


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