Regulation of Lipopolysaccharide-induced Genes Expression in Mouse Macrophages
Date Issued
2007
Date
2007
Author(s)
Chen, Yu-Ling
DOI
en-US
Abstract
Tristetraprolin (TTP) is an mRNA-destabilizing protein that negatively regulates the expression of proinflammatory mediators such as TNF-α. However, the mechanism of transcriptional regulation of TTP remains ill defined. Here we investigate the regulation of TTP as well as TNF-a expression in the mouse macrophage cell line RAW264.7. We found that pharmacological inhibition of NF-κB (BAY), proteasome (MG132) and p38 pathway (SB203580) resulted in downregulation of LPS-induced TTP mRNA and protein expression. A novel NF-κB binding element located within -1838 to -1859 relative to TTP transcription start site was identified and confirmed by ChIP experiments. Functional analysis using luciferase reporter assay demonstrated that TTP promoter activity was suppressed by SB203580 treatment. The half-life of TTP mRNA was also decreased by SB203580 treatment. These data suggest that p38 pathway regulates TTP expression at both transcriptional and post-transcriptional levels. Furthermore, the HDAC inhibitor, TSA, decreases the LPS-stimulated TNF-α mRNA expression. TSA is a general inhibitor of HDAC enzyme activity that results in chromatin structure loosening and transcriptional upregulation. In contrary, our data showed that TSA reduced the TNF-α promoter activity by luciferase reporter analysis. Interestingly, TSA disrupts NF-κB recruitment to TNF-α promoter without affecting NF-κB nuclear localization. Taken together, these results suggest that TTP mRNA transcription may be regulated by NF-κB while p38 signaling could modulate both TTP and TNF-α expression at both transcriptional and post-transcriptional levels during LPS stimulation.
Subjects
脂多醣
巨噬細胞
lipopolysaccharide
macrophage
TTP
TNF-alpha
Type
other
File(s)![Thumbnail Image]()
Loading...
Name
ntu-96-D89242001-1.pdf
Size
23.31 KB
Format
Adobe PDF
Checksum
(MD5):c8b7d4f8c31ed823049e3aa64105f456