scholarly journals PKCϵ is involved in JNK activation that mediates LPS-induced TNF-α, which induces apoptosis in macrophages

2003 ◽  
Vol 285 (5) ◽  
pp. C1235-C1245 ◽  
Author(s):  
Mònica Comalada ◽  
Jordi Xaus ◽  
Annabel F. Valledor ◽  
Carlos López-López ◽  
Daniel J. Pennington ◽  
...  
Keyword(s):  
Cell Model ◽  
Primary Cultures ◽  
Signaling Mechanism ◽  
Major Function ◽  
Tnf Α ◽  
Mitogen Activated Protein ◽  
Induced Apoptosis ◽  
Factor Α ◽  
Jnk Activation ◽  
Necrosis Factor

Lipopolysaccharide (LPS) is a powerful stimulator of macrophages and induces apoptosis in these cells. Using primary cultures of bone marrow-derived macrophages, we found that the autocrine production of tumor necrosis factor-α (TNF-α) has a major function in LPS-induced apoptosis. LPS activates PKC and regulates the different mitogen-activated protein kinases (MAPK). We aimed to determine its involvement either in the secretion of TNF-α or in the induction of apoptosis. Using specific inhibitors and mice with the gene for PKCϵ disrupted, we found that LPS-induced TNF-α-dependent apoptosis is mostly mediated by PKCϵ, which is not directly involved in the signaling mechanism of apoptosis but rather in the process of TNF-α secretion. In our cell model, all three MAPKs were involved in the regulation of TNF-α secretion, but at different levels. JNK mainly regulates TNF-α transcription and apoptosis, whereas ERK and p38 contribute to the regulation of TNF-α production, probably through posttranscriptional mechanisms. Only JNK activity is mediated by PKCϵ in response to LPS and so plays a major role in TNF-α secretion and LPS-induced apoptosis. We demonstrated in macrophages that LPS involving PKCϵ regulates JNK activity and produces TNF-α, which induces apoptosis.

Increased cytochrome P-450 2E1 expression sensitizes hepatocytes to c-Jun-mediated cell death from TNF-α

2002 ◽  
Vol 282 (2) ◽  
pp. G257-G266 ◽  
Author(s):  
Hailing Liu ◽  
Brett E. Jones ◽  
Cynthia Bradham ◽  
Mark J. Czaja
Keyword(s):  
Cell Death ◽  
Oxidant Stress ◽  
Nuclear Factor Κb ◽  
Dominant Negative ◽  
Tnf Α ◽  
Cyp2e1 Expression ◽  
Factor Α ◽  
Jnk Activation ◽  
Cytochrome P 450 ◽  
Necrosis Factor

The mechanisms underlying hepatocyte sensitization to tumor necrosis factor-α (TNF-α)-mediated cell death remain unclear. Increases in hepatocellular oxidant stress such as those that occur with hepatic overexpression of cytochrome P-450 2E1 (CYP2E1) may promote TNF-α death. TNF-α treatment of hepatocyte cell lines with differential CYP2E1 expression demonstrated that overexpression of CYP2E1 converted the hepatocyte TNF-α response from proliferation to apoptotic and necrotic cell death. Death occurred despite the presence of increased levels of nuclear factor-κB transcriptional activity and was associated with increased lipid peroxidation and GSH depletion. CYP2E1-overexpressing hepatocytes had increased basal and TNF-α-induced levels of c-Jun NH2-terminal kinase (JNK) activity, as well as prolonged JNK activation after TNF-α stimulation. Sensitization to TNF-α-induced cell death by CYP2E1 overexpression was inhibited by antioxidants or adenoviral expression of a dominant-negative c-Jun. Increased CYP2E1 expression sensitized hepatocytes to TNF-α toxicity mediated by c-Jun and overwhelming oxidative stress. The chronic increase in intracellular oxidant stress created by CYP2E1 overexpression may serve as a mechanism by which hepatocytes are sensitized to TNF-α toxicity in liver disease.

133 ROLE OF CASPASE-9 AND STAGE OF DEVELOPMENT IN INDUCTION OF APOPTOSIS BY HEAT SHOCK AND TUMOR NECROSIS FACTOR-α IN BOVINE PRE-IMPLANTATION EMBRYOS

2006 ◽  
Vol 18 (2) ◽  
pp. 175
Author(s):  
B. Loureiro ◽  
A. M. Brad ◽  
P. J. Hansen
Keyword(s):  
Heat Shock ◽  
Tumor Necrosis ◽  
Cell Number ◽  
Caspase 9 ◽  
Stage Of Development ◽  
Tnf Α ◽  
Induction Of Apoptosis ◽  
Induced Apoptosis ◽  
Factor Α ◽  
Necrosis Factor

Heat shock and tumor necrosis factor-α (TNF-α) can increase apoptosis in bovine embryos in a developmental-dependent manner. It was hypothesized that addition of the caspase-9 inhibitor, z-LEHD-fmk, would block induction of apoptosis caused by heat shock of 41°C and TNF-α. Furthermore, it was hypothesized that the magnitude of induced apoptosis would increase with stage of development. Embryos were collected on day 4, 5, and 6 after in vitro insemination and were cultured for 24 h in the presence of either 100 μm z-LEHD-fmk reconstituted in 0.5% (v/v) dimethyl sulfoxide or vehicle dimethyl sulfoxide at either (1) 38.5°C for 24 h (control), (2) 41°C for 15 h followed by 38.5°C for 9 h, or (3) 38.5°C for 24 h with 10 ng/mL murine TNF-α. Embryos were then fixed, and the proportion of blastomeres undergoing apoptosis was determined using TUNEL labeling. Heat shock did not increase the percentage of blastomeres that were TUNEL-positive (% apoptosis) at day 4 (n = 100 embryos total). In contrast, heat shock increased % apoptosis at day 5 and day 6 (P < 0.04) and this effect was blocked by z-LEHD-fmk (temperature × inhibitor, P < 0.04). At day 5, % apoptosis in the absence and presence of z-LEHD-fmk was 3.8 ± 1.9% and 3.7 ± 1.7% at 38.5°C vs. 8.9 ± 1.5% and 4.1 ± 1.7% at 41°C (n = 75 embryos total). At day 6, % apoptosis in the absence and presence of z-LEHD-fmk was 3.6 ± 1.1% and 3.7 ± 1.2% at 38.5°C vs. 11.1 ± 1.1% and 6.1 ± 1.2% at 41°C (n = 168 embryos total). Mean cell number at the end of culture ranged from 21 to 26 cells at day 4, 43 to 73 cells at day 5, and 101 to 114 cells at day 6. Treatment with TNF-α also increased apoptosis at all days (P < 0.01), and z-LEHD-fmk blocked this effect (TNF × inhibitor, P = 0.05; n = 361 embryos total). Across days, % apoptosis was 3.6 ± 1.4% (control), 3.3 ± 1.3% (inhibitor), 11.1 ± 1.3% (TNF-α), and 6.0 ± 1.4% (TNF-α + inhibitor). Mean cell number at the end of culture ranged from 21 to 27 cells at day 4, 59 to 74 cells at day 5, and 105 to 115 cells at day 6. In conclusion, activation of caspase-9 dependent pathways is involved in the induction of apoptosis by heat shock and TNF-α. Moreover, the magnitude of induced apoptosis increases as embryos advance in development. This work was supported by USDA Grant No. 2004–34135–14715 and BARD Grant No. US–3551–04.

Tumor necrosis factor-α and ceramide induce cell death through different mechanisms in rat mesangial cells

1999 ◽  
Vol 276 (3) ◽  
pp. F390-F397 ◽  
Author(s):  
Yan-Lin Guo ◽  
Baobin Kang ◽  
Li-Jun Yang ◽  
John R. Williamson
Keyword(s):  
Cell Death ◽  
Protein Kinase ◽  
Tumor Necrosis Factor ◽  
Tumor Necrosis ◽  
Tumor Necrosis Factor Α ◽  
Mesangial Cells ◽  
Tnf Α ◽  
Induced Apoptosis ◽  
Factor Α ◽  
Necrosis Factor

It has been proposed that ceramide acts as a cellular messenger to mediate tumor necrosis factor-α (TNF-α)-induced apoptosis. Based on this hypothesis, it was postulated that resistance of some cells to TNF-α cytotoxicity was due to an insufficient production of ceramide on stimulation by TNF-α. The present study was initiated to investigate whether this was the case in mesangial cells, which normally are insensitive to TNF-α-induced apoptosis. Our results indicate that although C2ceramide was toxic to mesangial cells, the cell death it induced differed both morphologically and biochemically from that induced by TNF-α in the presence of cycloheximide (CHX). The most apparent effect of C2ceramide was to cause cells to swell, followed by disruption of the cell membrane. It is evident that C2ceramide caused cell death by necrosis, whereas TNF-α in the presence of CHX killed the cells by apoptosis. C2ceramide did not mimic the effects of TNF-α on the activation of c-Jun NH2-terminal protein kinase and nuclear factor-κB transcription factor. Although mitogen-activated protein kinase [extracellular signal-related kinase (ERK)] was activated by both C2ceramide and TNF-α, such activation appeared to be mediated by different mechanisms as judged from the kinetics of ERK activation. Furthermore, the cleavage of cytosolic phospholipase A2during cell death induced by C2ceramide and by TNF-α in the presence of CHX showed distinctive patterns. The present study provides evidence that apoptosis and necrosis use distinctive signaling machinery to cause cell death.

scholarly journals Contrasting Effects of IG20 and Its Splice Isoforms, MADD and DENN-SV, on Tumor Necrosis Factor α-induced Apoptosis and Activation of Caspase-8 and -3

2001 ◽  
Vol 276 (50) ◽  
pp. 47202-47211 ◽  
Author(s):  
Adeeb M. Al-Zoubi ◽  
Elena V. Efimova ◽  
Shashi Kaithamana ◽  
Osvaldo Martinez ◽  
Mohammed El-Azami El-Idrissi ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Tumor Necrosis Factor ◽  
Tumor Necrosis ◽  
Tumor Necrosis Factor Α ◽  
Single Gene ◽  
Caspase 8 ◽  
Tnf Α ◽  
Induced Apoptosis ◽  
Factor Α ◽  
Necrosis Factor

We identified a novel cDNA (IG20) that is homologous to cDNAs encoding a proteindifferentiallyexpressed innormal andneoplastic cells (DENN-SV) and human MADD (MAPK-activatingdeathdomain-containing protein). Furthermore, we show that the above variants most likely result from alternative splicing of a single gene. Functional analyses of these variants in permanently transfected HeLa cells revealed that IG20 and DENN-SV render them more susceptible or resistant to tumor necrosis factor α (TNF-α)-induced apoptosis, respectively. All variants tested could interact with TNF receptor 1 and activate ERK and nuclear factor κB. However, relative to control cells, only cells expressing IG20 showed enhanced TNF-α-induced activation of caspase-8 and -3, whereas cells expressing DENN-SV showed either reduced or no caspase activation. Transfection of these cells with a cDNA encoding CrmA maximally inhibited apoptosis in HeLa-IG20 cells. Our results show that IG20 can promote TNF-α-induced apoptosis and activation of caspase-8 and -3 and suggest that it may play a novel role in the regulation of the pleiotropic effects of TNF-α through alternative splicing.

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