The tumour necrosis factor-α-mediated suppression of the CCAAT/enhancer binding protein-α gene transcription in hepatocytes involves inhibition of autoregulation

2009 ◽  
Vol 41 (5) ◽  
pp. 1189-1197 ◽  
Author(s):  
Pelagia Foka ◽  
Nishi N. Singh ◽  
Rebecca C. Salter ◽  
Dipak P. Ramji
Keyword(s):  
Tumour Necrosis Factor ◽  
Gene Transcription ◽  
Tumour Necrosis ◽  
Binding Protein ◽  
Tumour Necrosis Factor Α ◽  
Enhancer Binding Protein ◽  
Ccaat Enhancer Binding Protein ◽  
Factor Α ◽  
Necrosis Factor

scholarly journals Tumour necrosis factor-α regulates expression of the CCAAT-enhancer-binding proteins (C/EBPs) α and β and determines the occupation of the C/EBP site in the promoter of the insulin-responsive glucose-transporter gene in 3T3-L1 adipocytes

1999 ◽  
Vol 338 (3) ◽  
pp. 737-743 ◽  
Author(s):  
Renu JAIN ◽  
Shailaja POLICE ◽  
Kelle PHELPS ◽  
Phillip H. PEKALA
Keyword(s):  
Tumour Necrosis Factor ◽  
Tumour Necrosis ◽  
Protein C ◽  
Glucose Transporter ◽  
Tumour Necrosis Factor Α ◽  
Mobility Shift ◽  
Enhancer Binding Protein ◽  
Factor Α ◽  
Electrophoretic Mobility Shift Assays ◽  
Necrosis Factor

We have demonstrated previously that treatment of 3T3-L1 adipocytes with tumour necrosis factor-α (TNF) results in a rapid (4 h) and significant (75–80%) reduction in the rate of transcription of the GLUT4 gene. Control of GLUT4 gene transcription has been suggested at least in part to reside with the CCAAT-enhancer-binding protein (C/EBP) family (α, β and δ isoforms) of transcription factors. Using electrophoretic mobility shift assays, we have examined the ability of TNF to alter the occupation of the C/EBP site in the GLUT4 promoter. The data suggest that in fully differentiated adipocytes the C/EBP site is a ligand for predominantly α/α homodimers; however, after exposure to TNF, a shift in occupancy of the site occurs and the ligands become α/β heterodimers and β/β homodimers. Partner selection in dimer formation appears to be controlled by selective translocation of the β-isoform from the cytosol to the nucleus after exposure of the cells to TNF.

Post-transcriptional effects of extracellular pH on tumour necrosis factor-α production in RAW 246.7 and J774 A.1 cells

2001 ◽  
Vol 100 (3) ◽  
pp. 259-266 ◽  
Author(s):  
Thomas A. HEMING ◽  
Divina M. TUAZON ◽  
Sanat K. DAVÉ ◽  
Ashok K. CHOPRA ◽  
Johnny W. PETERSON ◽  
...  
Keyword(s):  
Tumour Necrosis Factor ◽  
Cell Lines ◽  
Gene Transcription ◽  
Tumour Necrosis ◽  
Extracellular Ph ◽  
Tumour Necrosis Factor Α ◽  
Tnf Α ◽  
J774 Cells ◽  
Factor Α ◽  
Necrosis Factor

The present studies determined the effects of extracellular pH (pHo) on the production of tumour necrosis factor-α (TNF-α) in the macrophage-like cell lines RAW 246.7 and J774 A.1. The cells were activated with lipopolysaccharide (LPS) at pHo 5.5, 6.5 or 7.4. TNF-α gene transcription was monitored by Northern blot analysis. Synthesis of the cytokine was monitored by ELISA measurements of the TNF-α content of cell-conditioned media (extracellularly released TNF-α) and cell lysates (cytosolic TNF-α). The magnitude of the TNF-α response differed markedly between the two cell lines. RAW cells were more responsive to LPS than were J774 cells. However, the effects of pHo on TNF-α production were similar in the two cell lines. TNF-α gene transcription was insensitive to experimental pHo. The pHo had no effect on the abundance of TNF-α mRNA at 2, 4 or 18 h. Nonetheless, synthesis of TNF-α was affected significantly by pHo. The TNF-α contents of cell-conditioned medium and cell lysate at 18 h were reduced progressively at lower pHo values. The data indicate that pHo alters TNF-α production in RAW and J774 cells at a post-transcriptional level. These findings suggest that pHo influences the phenotypic responses of macrophages to activating stimuli and modifies the role that macrophages play in inflammatory and immune actions.

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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