scholarly journals The ERK Mitogen-Activated Protein Kinase Pathway Contributes to Ebola Virus Glycoprotein-Induced Cytotoxicity

2006 ◽  
Vol 81 (3) ◽  
pp. 1230-1240 ◽  
Author(s):  
Carisa A. Zampieri ◽  
Jean-Francois Fortin ◽  
Garry P. Nolan ◽  
Gary J. Nabel
Keyword(s):  
Cell Death ◽  
Ebola Virus ◽  
Active Form ◽  
Growth Factor Receptor ◽  
Hemorrhagic Fever ◽  
Dominant Negative ◽  
Mitogen Activated Protein Kinase ◽  
Viral Gene ◽  
Mutant Form ◽  
Growth And Survival

ABSTRACT Ebola virus is a highly lethal pathogen that causes hemorrhagic fever in humans and nonhuman primates. Among the seven known viral gene products, the envelope glycoprotein (GP) alone induces cell rounding and detachment that ultimately leads to cell death. Cellular cytoxicity is not seen with comparable levels of expression of a mutant form of GP lacking a mucin-like domain (GPΔmuc). GP-induced cell death is nonapoptotic and is preceded by downmodulation of cell surface molecules involved in signaling pathways, including certain integrins and epidermal growth factor receptor. To investigate the mechanism of GP-induced cellular toxicity, we analyzed the activation of several signal transduction pathways involved in cell growth and survival. The active form of extracellular signal-regulated kinases types 1 and 2 (ERK1/2), phospho-ERK1/2, was reduced in cells expressing GP compared to those expressing GPΔmuc as determined by flow cytometry, in contrast to the case for several other signaling proteins. Subsequent analysis of the activation states and kinase activities of related kinases revealed a more pronounced effect on the ERK2 kinase isoform. Disruption of ERK2 activity by a dominant negative ERK or by small interfering RNA-mediated ERK2 knockdown potentiated the decrease in αV integrin expression associated with toxicity. Conversely, activation of the pathway through the expression of a constitutively active form of ERK2 significantly protected against this effect. These results indicate that the ERK signaling cascade mediates GP-mediated cytotoxicity and plays a role in pathogenicity induced by this gene product.

scholarly journals Bcl-2 does not require Raf kinase activity for its death-protective function

1997 ◽  
Vol 324 (1) ◽  
pp. 75-83 ◽  
Author(s):  
Reynald OLIVIER ◽  
Isabelle OTTER ◽  
Laurent MONNEY ◽  
Markus WARTMANN ◽  
Christoph BORNER
Keyword(s):  
Cell Death ◽  
Mammalian Cells ◽  
Kinase Activity ◽  
Survival Function ◽  
Active Form ◽  
Signal Transduction Pathway ◽  
Dominant Negative ◽  
Mitogen Activated Protein Kinase ◽  
Protective Function

It has been widely accepted that the oncogene product bcl-2 protects mammalian cells from programmed cell death (apoptosis). The molecules and signalling pathways upon which bcl-2 acts are, however, still ill-defined. Recently, bcl-2 was shown to interact with c-raf-1 in vitro. Furthermore, an active form of c-raf-1 delayed apoptosis induced by trophic factor deprivation and enhanced the death-suppressive function of bcl-2 when co-expressed. This has led to the hypothesis that bcl-2 communicates cell-death protection via a raf-dependent signal transduction pathway. Here we show, by various immunological and biochemical methods, that bcl-2 does not stably associate with c-raf-1 in cellular extracts prepared from fibroblasts before or after treatment with agents that induce apoptosis. Unexpectedly, bcl-2 function is entirely maintained, if not improved, when raf-dependent signalling is experimentally abrogated. In fact, bcl-2 allows the stable overexpression of a kinase-defective dominant-negative raf mutant that usually interferes with cell viability and/or proliferation. Our results indicate that bcl-2 does not require c-raf-1 kinase activity and an associated mitogen-activated protein kinase signalling pathway for its survival function. This property may be exploited to dissect cellular events that are dependent or independent of c-raf-1 kinase activity.

scholarly journals Regulation of Cyclooxygenase 2 mRNA Stability by the Mitogen-Activated Protein Kinase p38 Signaling Cascade

2000 ◽  
Vol 20 (12) ◽  
pp. 4265-4274 ◽  
Author(s):  
Marina Lasa ◽  
Kamal R. Mahtani ◽  
Andrew Finch ◽  
Gary Brewer ◽  
Jeremy Saklatvala ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Mrna Stability ◽  
Active Form ◽  
Cyclooxygenase 2 ◽  
Dominant Negative ◽  
Mitogen Activated Protein Kinase ◽  
Signaling Cascade ◽  
Mitogen Activated Protein ◽  
Cox 2 ◽  
Constitutively Active

ABSTRACT A tetracycline-regulated reporter system was used to investigate the regulation of cyclooxygenase 2 (Cox-2) mRNA stability by the mitogen-activated protein kinase (MAPK) p38 signaling cascade. The stable β-globin mRNA was rendered unstable by insertion of the 2,500-nucleotide Cox-2 3′ untranslated region (3′ UTR). The chimeric transcript was stabilized by a constitutively active form of MAPK kinase 6, an activator of p38. This stabilization was blocked by SB203580, an inhibitor of p38, and by two different dominant negative forms of MAPK-activated protein kinase 2 (MAPKAPK-2), a kinase lying downstream of p38. Constitutively active MAPKAPK-2 was also able to stabilize chimeric β-globin–Cox-2 transcripts. The MAPKAPK-2 substrate hsp27 may be involved in stabilization, as β-globin–Cox-2 transcripts were partially stabilized by phosphomimetic mutant forms of hsp27. A short (123-nucleotide) fragment of the Cox-2 3′ UTR was necessary and sufficient for the regulation of mRNA stability by the p38 cascade and interacted with a HeLa protein immunologically related to AU-rich element/poly(U) binding factor 1.

scholarly journals Role of MKK3 and p38 MAPK in cytokine-induced death of insulin-producing cells

2005 ◽  
Vol 393 (1) ◽  
pp. 129-139 ◽  
Author(s):  
Natalia Makeeva ◽  
Jason W. Myers ◽  
Nils Welsh
Keyword(s):  
Nitric Oxide ◽  
Cell Death ◽  
Protein Kinase ◽  
P38 Mapk ◽  
Dominant Negative ◽  
Mitogen Activated Protein Kinase ◽  
Nitric Oxide Donor ◽  
Cell Leukaemia ◽  
Dominant Negative Mutant

The aim of the present investigation was to elucidate further the importance of p38 MAPK (mitogen-activated protein kinase) in nitric oxide- and cytokine-induced β-cell death. For this purpose, isolated human islets were treated with d-siRNA (diced small interfering RNA) and then exposed to the nitric oxide donor DETA/NONOate [2,2′-(hydroxynitrosohydrazono)bis-ethanamine]. We observed that cells treated with p38α-specific d-siRNA, but not with d-siRNA targeting GL3 (a firefly luciferase siRNA plasmid) or PKCδ (protein kinase Cδ), were protected against nitric oxide-induced death. This was paralleled by an increased level of Bcl-XL (B-cell leukaemia/lymphoma-X long). For an in-depth study of the mechanisms of p38 activation, MKK3 (MAPK kinase 3), MKK6 and their dominant-negative mutants were overexpressed in insulin-producing RIN-5AH cells. In transient transfections, MKK3 overexpression resulted in increased p38 phosphorylation, whereas in stable MKK3-overexpressing RIN-5AH clones, the protein levels of p38 and JNK (c-Jun N-terminal kinase) were decreased, resulting in unaffected phospho-p38 levels. In addition, a long-term MKK3 overexpression did not affect cell death rates in response to the cytokines interleukin-1β and interferon-γ, whereas a short-term MKK3 expression resulted in increased cytokine-induced RIN-5AH cell death. The MKK3-potentiating effect on cytokine-induced cell death was abolished by a nitric oxide synthase inhibitor, and MKK3-stimulated p38 phosphorylation was enhanced by inhibitors of phosphatases. Finally, as the dominant-negative mutant of MKK3 did not affect cytokine-induced p38 phosphorylation, and as wild-type MKK3 did not influence p38 autophosphorylation, it may be that p38 is activated by MKK3/6-independent pathways in response to cytokines and nitric oxide. In addition, it is likely that a long-term increase in p38 activity is counteracted by both a decreased expression of the p38, JNK and p42 genes as well as an increased dephosphorylation of p38.

Coriandrum sativumSuppresses Aβ42-Induced ROS Increases, Glial Cell Proliferation, and ERK Activation

2016 ◽  
Vol 44 (07) ◽  
pp. 1325-1347 ◽  
Author(s):  
Quan Feng Liu ◽  
Haemin Jeong ◽  
Jang Ho Lee ◽  
Yoon Ki Hong ◽  
Youngje Oh ◽  
...  
Keyword(s):  
Glial Cell ◽  
Mammalian Cells ◽  
Molecular Mechanisms ◽  
Active Form ◽  
Growth Factor Receptor ◽  
Ethanol Extract ◽  
Cell Number ◽  
Mitogen Activated Protein Kinase ◽  
Neuroprotective Effects ◽  
Protective Function

Alzheimer’s disease (AD), the most common neurodegenerative disease, has a complex and widespread pathology that is characterized by the accumulation of amyloid [Formula: see text]-peptide (A[Formula: see text]) in the brain and various cellular abnormalities, including increased oxidative damage, an amplified inflammatory response, and altered mitogen-activated protein kinase signaling. Based on the complex etiology of AD, traditional medicinal plants with multiple effective components are alternative treatments for patients with AD. In the present study, we investigated the neuroprotective effects of an ethanol extract of Coriandrum sativum (C. sativum) leaves on A[Formula: see text] cytotoxicity and examined the molecular mechanisms underlying the beneficial effects. Although recent studies have shown the benefits of the inhalation of C. sativum oil in an animal model of AD, the detailed molecular mechanisms by which C. sativum exerts its neuroprotective effects are unclear. Here, we found that treatment with C. sativum extract increased the survival of both A[Formula: see text]-treated mammalian cells and [Formula: see text]42-expressing flies. Moreover, C. sativum extract intake suppressed [Formula: see text]-induced cell death in the larval imaginal disc and brain without affecting A[Formula: see text]42 expression and accumulation. Interestingly, the increases in reactive oxygen species levels and glial cell number in AD model flies were reduced by C. sativum extract intake. Additionally, C. sativum extract inhibited the epidermal growth factor receptor- and A[Formula: see text]-induced phosphorylation of extracellular signal-regulated kinase (ERK). The constitutively active form of ERK abolished the protective function of C. sativum extract against the [Formula: see text]-induced eye defect phenotype in Drosophila. Taken together, these results suggest that C. sativum leaves have antioxidant, anti-inflammatory, and ERK signaling inhibitory properties that are beneficial for patients with AD.

Permissive effect of EGFR-activated pathways on RVI and their anti-apoptotic effect in hypertonicity-exposed mIMCD3 cells

2011 ◽  
Vol 31 (6) ◽  
pp. 489-497 ◽  
Author(s):  
Alejandro Ruiz-Martínez ◽  
Erika Vázquez-Juárez ◽  
Gerardo Ramos-Mandujano ◽  
Herminia Pasantes-Morales
Keyword(s):  
Cell Death ◽  
Protein Kinase ◽  
Apoptotic Cell ◽  
Growth Factor Receptor ◽  
Mitogen Activated Protein Kinase ◽  
Egfr Inhibition ◽  
Mitogen Activated Protein ◽  
Apoptotic Effect ◽  
Phosphoinositide 3 Kinase

Hypertonicity is a stressful stimulus leading to cell shrinkage and apoptotic cell death. Apoptosis can be prevented if cells are able to activate the mechanism of RVI (regulatory volume increase). This study in mIMCD3 cells presents evidence of a permissive role of the EGFR (epidermal growth factor receptor) on RVI, achieved for the most part through the two main EGFR-triggered signalling chains, the MAPK (mitogen-activated protein kinase)/ERK (extracellular-signal-regulated kinase) and the PI3K (phosphoinositide 3-kinase)/Akt (also known as protein kinase B) pathways. Hyperosmotic solutions (450 mosM) made by addition of NaCl, increased EGFR phosphorylation, which is prevented by GM6001 and AG1478, blockers respectively, of MMPs (matrix metalloproteinases) and EGFR. Inhibition of EGFR, ERK (PD98059) or PI3K/Akt (wortmannin) phosphorylation reduced RVI by 60, 48 and 58% respectively. The NHE (Na+/H+ exchanger) seems to be the essential mediator of this effect since (i) NHE is the main contributor to RVI, (ii) EGFR, ERK and PI3K/Akt blockers added together with the NHE blocker zoniporide reduce RVI by non-additive effects and (iii) All the blockers significantly lowered the NHE rate in cells challenged by an NH4Cl pulse. Besides reducing RVI, the inhibition of MMP, EGFR and PI3K/Akt had a strong pro-apoptotic effect increasing cell death by 2–3.7-fold. This effect was significantly lower when RVI inhibition did not involve the EGFR-PI3K/Akt pathway. These results provide evidence that Akt and its permissive effect on RVI have a predominant influence on cell survival under hypertonic conditions in IMCD3 cells. This role of Akt operates under the influence of EGFR activation, promoted by MMP.

scholarly journals Cell Death or Survival Promoted by Alternative Isoforms of ErbB4

2010 ◽  
Vol 21 (23) ◽  
pp. 4275-4286 ◽  
Author(s):  
Maria Sundvall ◽  
Ville Veikkolainen ◽  
Kari Kurppa ◽  
Zaidoun Salah ◽  
Denis Tvorogov ◽  
...  
Keyword(s):  
Cell Death ◽  
Target Gene ◽  
Kinase Inhibitor ◽  
Tumor Biology ◽  
Growth Factor Receptor ◽  
Cellular Growth ◽  
Growth And Survival ◽  
Factor Receptor Alpha ◽  
Alternatively Spliced ◽  
Erbb4 Gene

The significance of ErbB4 in tumor biology is poorly understood. The ERBB4 gene is alternatively spliced producing juxtamembrane (JM-a and JM-b) and cytoplasmic (CYT-1 and CYT-2) isoforms. Here, signaling via the two alternative ErbB4 JM isoforms (JM-a CYT-2 and JM-b CYT-2) was compared. Fibroblasts expressing ErbB4 JM-a demonstrated enhanced ErbB4 autophosphorylation, growth, and survival. In contrast, cells overexpressing ErbB4 JM-b underwent starvation-induced death. Both pro- and antisurvival responses to the two ErbB4 isoforms were sensitive to an ErbB kinase inhibitor. Platelet-derived growth factor receptor-alpha (PDGFRA) was identified as an ErbB4 target gene that was differentially regulated by the two ErbB4 isoforms. The soluble intracellular domain of ErbB4, released from the JM-a but not from the JM-b isoform, associated with the transcription factor AP-2 and promoted its potential to enhance PDGFRA transcription. Survival of cells expressing JM-a was suppressed by targeting either PDGFR-α or AP-2, whereas cells expressing JM-b were rescued from cell death by the PDGFR-α agonist, PDGF-BB. These findings indicate that two alternative ErbB4 isoforms may promote antagonistic cellular responses and suggest that pharmacological inhibition of ErbB4 kinase activity may lead to either suppression or promotion of cellular growth.

scholarly journals Deoxycholic Acid (DCA) Causes Ligand-independent Activation of Epidermal Growth Factor Receptor (EGFR) and FAS Receptor in Primary Hepatocytes: Inhibition of EGFR/Mitogen-activated Protein Kinase-Signaling Module Enhances DCA-induced Apoptosis

2001 ◽  
Vol 12 (9) ◽  
pp. 2629-2645 ◽  
Author(s):  
Liang Qiao ◽  
Elaine Studer ◽  
Kevin Leach ◽  
Robert McKinstry ◽  
Seema Gupta ◽  
...  
Keyword(s):  
Bile Acid ◽  
Mapk Pathway ◽  
Growth Factor Receptor ◽  
Mapk Signaling ◽  
Dominant Negative ◽  
Mitogen Activated Protein Kinase ◽  
Caspase 8 ◽  
Mapk Activation ◽  
Fas Receptor ◽  
Induced Apoptosis

Previous studies have argued that enhanced activity of the epidermal growth factor receptor (EGFR) and the mitogen-activated protein kinase (MAPK) pathway can promote tumor cell survival in response to cytotoxic insults. In this study, we examined the impact of MAPK signaling on the survival of primary hepatocytes exposed to low concentrations of deoxycholic acid (DCA, 50 μM). Treatment of hepatocytes with DCA caused MAPK activation, which was dependent upon ligand independent activation of EGFR, and downstream signaling through Ras and PI3 kinase. Neither inhibition of MAPK signaling alone by MEK1/2 inhibitors, nor exposure to DCA alone, enhanced basal hepatocyte apoptosis, whereas inhibition of DCA-induced MAPK activation caused ∼25% apoptosis within 6 h. Similar data were also obtained when either dominant negative EGFR-CD533 or dominant negative Ras N17 were used to block MAPK activation. DCA-induced apoptosis correlated with sequential cleavage of procaspase 8, BID, procaspase 9, and procaspase 3. Inhibition of MAPK potentiated bile acid-induced apoptosis in hepatocytes with mutant FAS-ligand, but did not enhance in hepatocytes that were null for FAS receptor expression. These data argues that DCA is causing ligand independent activation of the FAS receptor to stimulate an apoptotic response, which is counteracted by enhanced ligand-independent EGFR/MAPK signaling. In agreement with FAS-mediated cell killing, inhibition of caspase function with the use of dominant negative Fas-associated protein with death domain, a caspase 8 inhibitor (Ile-Glu-Thr-Asp-p-nitroanilide [IETD]) or dominant negative procaspase 8 blocked the potentiation of bile acid-induced apoptosis. Inhibition of bile acid-induced MAPK signaling enhanced the cleavage of BID and release of cytochrome cfrom mitochondria, which were all blocked by IETD. Despite activation of caspase 8, expression of dominant negative procaspase 9 blocked procaspase 3 cleavage and the potentiation of DCA-induced apoptosis. Treatment of hepatocytes with DCA transiently increased expression of the caspase 8 inhibitor proteins c-FLIP-S and c-FLIP-L that were reduced by inhibition of MAPK or PI3 kinase. Constitutive overexpression of c-FLIP-s abolished the potentiation of bile acid-induced apoptosis. Collectively, our data argue that loss of DCA-induced EGFR/Ras/MAPK pathway function potentiates DCA-stimulated FAS-induced hepatocyte cell death via a reduction in the expression of c-FLIP isoforms.

scholarly journals Rhomboid and Star facilitate presentation and processing of the Drosophila TGF-α homolog Spitz

2000 ◽  
Vol 14 (2) ◽  
pp. 177-186 ◽  
Author(s):  
Anne G. Bang ◽  
Chris Kintner
Keyword(s):  
Epidermal Growth Factor Receptor ◽  
Transmembrane Domain ◽  
Active Form ◽  
Growth Factor Receptor ◽  
Transmembrane Proteins ◽  
Soluble Form ◽  
Mutant Form ◽  
Dependent Manner ◽  
Epidermal Growth ◽  
Membrane Bound

Activation of the Drosophila epidermal growth factor receptor (DER) by the transmembrane ligand, Spitz (Spi), requires two additional transmembrane proteins, Rhomboid and Star. Genetic evidence suggests that Rhomboid and Star facilitate DER signaling by processing membrane-bound Spi (mSpi) to an active, soluble form. To test this model, we use an assay based on Xenopus animal cap explants in which Spi activation of DER is Rhomboid and Star dependent. We show that Spi is on the cell surface but is kept in an inactive state by its cytoplasmic and transmembrane domains; Rhomboid and Star relieve this inhibition, allowing Spi to signal. We show further that Spi is likely to be cleaved within its transmembrane domain. However, a mutant form of mSpi that is not cleaved still signals to DER in a Rhomboid and Star-dependent manner. These results suggest strongly that Rhomboid and Star act primarily to present an active form of Spi to DER, leading secondarily to the processing of Spi into a secreted form.

scholarly journals Gi2-mediated activation of the MAP kinase cascade.

1995 ◽  
Vol 6 (12) ◽  
pp. 1685-1695 ◽  
Author(s):  
A M Pace ◽  
M Faure ◽  
H R Bourne
Keyword(s):  
Cellular Proliferation ◽  
Transmembrane Domain ◽  
Mapk Pathway ◽  
Chinese Hamster Ovary Cells ◽  
Active Form ◽  
Chinese Hamster ◽  
Mapk Signaling ◽  
Dominant Negative ◽  
Mitogen Activated Protein Kinase ◽  
Dominant Negative Mutant

The Gi class of heterotrimeric G proteins has been implicated in transmitting mitogenic signals from a variety of seven-transmembrane domain receptors. In addition, the alpha subunit of Gi2 (alpha i2) is oncogenic when mutated to a constitutively active form (gip2). The mechanism by which Gi2 stimulates cellular proliferation is unknown, but is believed to involve activation of the mitogen-activated protein kinase (MAPK) signaling cascade. To study Gi2 activation of the cascade, we transiently expressed a mutant, pertussis toxin (PTX)-resistant alpha i2 in Chinese hamster ovary cells. After PTX treatment of these cells, Gi-coupled receptors specifically activated PTX-resistant Gi2 without activating other Gi proteins. Receptor-mediated activation of Gi2 led to activation of MAPK and its upstream activator, MAPK/ERK-activating kinase (MEK). Activation of MAPK and MEK by Gi2 was blocked by expression of a dominant-negative mutant of Ras. Gi2 activation did not, however, detectably increase the proportion of Ras protein in the GTP-bound form. Additional experiments suggest that Gi2 stimulates the MAPK pathway, at least in part, by mechanisms that involve release of its beta gamma subunit, as well as activation of phosphatidylinositol-3 kinase.

scholarly journals Apoptosis Suppression by Raf-1 and MEK1 Requires MEK- and Phosphatidylinositol 3-Kinase-Dependent Signals

2001 ◽  
Vol 21 (7) ◽  
pp. 2324-2336 ◽  
Author(s):  
Alexander von Gise ◽  
Petra Lorenz ◽  
Claudia Wellbrock ◽  
Brian Hemmings ◽  
Friederike Berberich-Siebelt ◽  
...  
Keyword(s):  
Cell Death ◽  
Cell Survival ◽  
Cell Line ◽  
Active Form ◽  
Dominant Negative ◽  
Phosphatidylinositol 3 Kinase ◽  
Interleukin 3 ◽  
Survival Signaling ◽  
Phosphatidylinositol 3 ◽  
Constitutively Active

ABSTRACT Two Ras effector pathways leading to the activation of Raf-1 and phosphatidylinositol 3-kinase (PI3K) have been implicated in the survival signaling by the interleukin 3 (IL-3) receptor. Analysis of apoptosis suppression by Raf-1 demonstrated the requirement for mitochondrial translocation of the kinase in this process. This could be achieved either by overexpression of the antiapoptotic protein Bcl-2 or by targeting Raf-1 to the mitochondria via fusion to the mitochondrial protein Mas p70. Mitochondrially active Raf-1 is unable to activate extracellular signal-related kinase 1 (ERK1) and ERK2 but suppresses cell death by inactivating the proapoptotic Bcl-2 family member BAD. However, genetic and biochemical data also have suggested a role for the Raf-1 effector module MEK-ERK in apoptosis suppression. We thus tested for MEK requirement in cell survival signaling using the interleukin 3 (IL-3)-dependent cell line 32D. MEK is essential for survival and growth in the presence of IL-3. Upon growth factor withdrawal the expression of constitutively active MEK1 mutants significantly delays the onset of apoptosis, whereas the presence of a dominant negative mutant accelerates cell death. Survival signaling by MEK most likely results from the activation of ERKs since expression of a constitutively active form of ERK2 was as effective in protecting NIH 3T3 fibroblasts against doxorubicin-induced cell death as oncogenic MEK. The survival effect of activated MEK in 32D cells is achieved by both MEK- and PI3K-dependent mechanisms and results in the activation of PI3K and in the phosphorylation of AKT. MEK and PI3K dependence is also observed in 32D cells protected from apoptosis by oncogenic Raf-1. Additionally, we also could extend these findings to the IL-3-dependent pro-B-cell line BaF3, suggesting that recruitment of MEK is a common mechanism for survival signaling by activated Raf. Requirement for the PI3K effector AKT in this process is further demonstrated by the inhibitory effect of a dominant negative AKT mutant on Raf-1-induced cell survival. Moreover, a constitutively active form of AKT synergizes with Raf-1 in apoptosis suppression. In summary these data strongly suggest a Raf effector pathway for cell survival that is mediated by MEK and AKT.

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