scholarly journals S-Adenosylmethionine attenuates the lipopolysaccharide-induced expression of the gene for tumour necrosis factor α

1999 ◽  
Vol 342 (1) ◽  
pp. 21-25 ◽  
Author(s):  
Walter H. WATSON ◽  
Yanming ZHAO ◽  
Rajender K. CHAWLA
Keyword(s):  
Liver Injury ◽  
Tumour Necrosis Factor ◽  
Tumour Necrosis ◽  
Elevated Serum ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Tumour Necrosis Factor Α ◽  
Tnf Gene ◽  
Factor Α ◽  
Necrosis Factor

Intracellular deficiency of S-adenosylmethionine (AdoMet) and elevated serum concentrations of tumour necrosis factor α (TNF) are hallmarks of toxin-induced liver injury. In these models, the administration of either exogenous AdoMet or antibody/soluble receptor for TNF attenuates the injury. We have demonstrated previously that the administration of exogenous AdoMet to AdoMet-deficient rats attenuated lipopolysaccharide (LPS)-induced liver injury and serum TNF concentrations. Here we report that AdoMet lowered the amount of TNF secreted by LPS-stimulated murine macrophage cells (RAW 264.7) in a dose-dependent manner. The inhibition of TNF release was correlated with changes in the steady-state TNF mRNA concentrations. Changes in TNF mRNA were not due to its altered stability and might have been due to an attenuation of the transcription rate of the TNF gene. The inhibition of TNF release in RAW cells was not mediated by GSH because treatment with AdoMet did not increase intracellular GSH. In addition, N-acetylcysteine, whereas it did increase GSH concentration, had no effect on LPS-stimulated TNF release in these cells. Exogenous AdoMet also attenuated LPS-induced serum TNF levels in normal rats sensitized with lead. Thus AdoMet administration might exert its hepatoprotective effects at least in part by its inhibitory effect on expression of the gene for TNF.

scholarly journals Modulation of macrophage activation by prostaglandins

1996 ◽  
Vol 5 (1) ◽  
pp. 14-17 ◽  
Author(s):  
L. Sautebin ◽  
R. Carnuccio ◽  
F. D'Acquisto ◽  
M. Di Rosa
Keyword(s):  
Nitric Oxide ◽  
Tumour Necrosis Factor ◽  
Tumour Necrosis ◽  
Phosphodiesterase Inhibitor ◽  
Inhibitory Effect ◽  
Prostaglandin E ◽  
Tumour Necrosis Factor Α ◽  
Nitric Oxide Release ◽  
Factor Α ◽  
Necrosis Factor

The effect of prostaglandtn E2, iloprost and cAMP on both nitric oxide and tumour necrosis factor-α release in J774 macrophages has been studied. Both prostaglandin E2and iloprost inhibited, in a concentration-dependent fashion, the lipopolysaccharide-induced generation of nitric oxide and tumour necrosis factor-α. The inhibitory effect of these prostanoids seems to be mediated by an increase of the second messenger cAMP since it was mimicked by dibutyryl cAMP and potentiated by the selective type IV phosphodiesterase inhibitor RO-20-1724. Our results suggest that the inhibition of nitric oxide release by prostaglandin E2and iloprost in lipopolysaccharide-activated J774 macrophages may be secondary to the inhibition of tumour necrosis factor-α generation, which in turn is likely to be mediated by cAMP.

Tumour necrosis factor-α gene expression and production in human umbilical arterial endothelial cells

2000 ◽  
Vol 98 (4) ◽  
pp. 461-470 ◽  
Author(s):  
Thomas NEUHAUS ◽  
Gudrun TOTZKE ◽  
Elisabeth GRUENEWALD ◽  
Hans-Peter JUESTEN ◽  
Agapios SACHINIDIS ◽  
...  
Keyword(s):  
Gene Expression ◽  
Endothelial Cells ◽  
Tumour Necrosis Factor ◽  
Tumour Necrosis ◽  
Dependent Manner ◽  
Tumour Necrosis Factor Α ◽  
Tnf Α ◽  
Factor Α ◽  
Arterial Endothelial Cells ◽  
Necrosis Factor

Endothelial cells act as an interface between the blood and tissues, and are known to be involved in inflammatory processes. These cells are responsive to and produce different cytokines. Tumour necrosis factor-α (TNF-α) not only is one of the most important inflammatory peptides, but also can be induced by lipopolysaccharide (LPS). The focus of the present study was on TNF-α gene expression and production in human umbilical arterial endothelial cells (HUAEC), including the kinetics of this process. Interleukin-1α (IL-1α), LPS and TNF-α, which are all known to be elevated in septic shock, were used as stimulators at concentrations commonly found in patients with sepsis. Through the use of reverse transcriptase/PCR, immunohistochemical reactions and ELISA techniques, we showed that, in HUAEC, all three stimuli were able to induce gene expression and production of TNF-α. Furthermore, this induction by IL-1α, LPS and TNF-α occurred in a time- and concentration-dependent manner in these cells. TNF-α expression and production was induced by all three agents at concentrations commonly found in patients with sepsis. TNF-α mRNA was observed within 30 min regardless of the stimulus used, but the levels peaked at different times. Since it is well established that TNF-α is able to induce the synthesis of IL-1α in endothelial cells and, as shown in the present study, TNF-α and IL-1α are themselves able to induce the synthesis of TNF-α in endothelial cells, an autocrine potentiation of cytokine release in sepsis can be proposed. This situation could lead to a locally acting ‘vicious cycle’ which, when considered in addition to the known ability of TNF-α to induce apoptosis, could mean that various organs will be damaged, a condition associated with sepsis. Thus these results provide further evidence for the important role played by the endothelium in inflammation.

scholarly journals Binding of a protein to an AU-rich domain of tumour necrosis factor α mRNA as a 35 kDa complex and its regulation in primary rat astrocytes

1996 ◽  
Vol 316 (2) ◽  
pp. 455-460 ◽  
Author(s):  
Youn-uck KIM ◽  
Horea G. RUS ◽  
Stephen N. FISHER ◽  
Paula M. PITHA ◽  
Moon L. SHIN
Keyword(s):  
Tumour Necrosis Factor ◽  
Tumour Necrosis ◽  
Protein Complexes ◽  
Binding Activity ◽  
Dependent Manner ◽  
Tumour Necrosis Factor Α ◽  
Rich Domain ◽  
Rat Astrocytes ◽  
Factor Α ◽  
Necrosis Factor

Newcastle disease virus (NDV) induces tumour necrosis factor α (TNFα) gene transcription and increases the mRNA stability. NDV stabilizes TNFα mRNA by preventing poly(A) shortening in a protein kinase C-dependent manner. TNFα3´-untranslated region (UTR) contains an AU-rich domain (ARD) with seven AUUUA pentamers, a motif implicated in poly(A) removal and mRNA degradation. In this report, protein binding to TNFα ARD and the effects of NDV and kinases on ARD-binding activity were investigated in primary rat astrocytes. Both nuclear and cytoplasmic extracts contained proteins binding to centrally located 27 nt AUUUAUUAUUUAUUUAUUAUUUAUUUA, within TNFαARD. Portions of ARD with a single AUUUA did not show ARD-binding activity. The ARD–protein complexes migrated as two bands on electrophoretic mobility-shift assay. The slower moving complexes appeared either as a broader band or doublets. The UV cross-linked ARD–protein complexes, however, migrated as a single 35 kDa band on SDS/PAGE. In cytoplasmic extracts treated with alkaline phosphatase there was a decrease in the faster moving complex and an increase in the slower moving complex, whereas NDV infection produced the reverse effect. In addition, the faster moving complex was decreased when cytoplasmic extracts from NDV-infected cells were treated with protein phosphatase 1 or 2A. Neither NDV infection nor phosphatase treatment affected the mobility pattern of nuclear extracts. The data indicate that a protein of molecular mass less than 35 kDa binds to a segment of TNFαARD containing primarily UUAUUUAUU motifs, and the ARD-binding activity in cytoplasmic compartment is post-transcriptionally modified.

Substrate specificity and inducibility of TACE (tumour necrosis factor α-converting enzyme) revisited: the Ala-Val preference, and induced intrinsic activity

2003 ◽  
Vol 70 ◽  
pp. 39-52 ◽  
Author(s):  
Roy A. Black ◽  
John R. Doedens ◽  
Rajeev Mahimkar ◽  
Richard Johnson ◽  
Lin Guo ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Recent Work ◽  
Tumour Necrosis Factor ◽  
Tumour Necrosis ◽  
Transforming Growth Factor ◽  
Intrinsic Activity ◽  
Converting Enzyme ◽  
Tumour Necrosis Factor Α ◽  
Factor Α ◽  
Necrosis Factor

Tumour necrosis factor α (TNFα)-converting enzyme (TACE/ADAM-17, where ADAM stands for a disintegrin and metalloproteinase) releases from the cell surface the extracellular domains of TNF and several other proteins. Previous studies have found that, while purified TACE preferentially cleaves peptides representing the processing sites in TNF and transforming growth factor α, the cellular enzyme nonetheless also sheds proteins with divergent cleavage sites very efficiently. More recent work, identifying the cleavage site in the p75 TNF receptor, quantifying the susceptibility of additional peptides to cleavage by TACE and identifying additional protein substrates, underlines the complexity of TACE-substrate interactions. In addition to substrate specificity, the mechanism underlying the increased rate of shedding caused by agents that activate cells remains poorly understood. Recent work in this area, utilizing a peptide substrate as a probe for cellular TACE activity, indicates that the intrinsic activity of the enzyme is somehow increased.

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