Transcriptional regulation of the rat glutamine synthetase gene by tumor necrosis factor-alpha.
The expression of glutamine synthetase (GS) is induced in rat skeletal muscle cells (L-6) in response to treatment with the inflammatory cytokine tumor necrosis factor alpha (TNF-alpha). This paper reports the regulation of GS expression in rat skeletal muscle which expresses high levels of GS. TNF-alpha treatment leads to a 3-4-fold increase in GS activity in a dose-dependent and time-dependent manner. Northern-blot analysis of GS mRNA revealed an increased mRNA concentration, reaching a peak at 12 h in response to TNF-alpha treatment. To monitor transcriptional activation of GS by TNF-alpha, and to identify a TNF-alpha-responsive element in the GS promoter, L6 cells were treated with TNF-alpha following transfection of GS-chloramphenicol-acetyltransferase (CAT) constructs. The first 251-bp fragment at the GS upstream sequence showed basal promoter activity, but failed to show any TNF-alpha-inducible activity. However, a 2.5-3-fold induction was noted in constructs extending up to 1.1 kb. This data demonstrates that the rat GS gene is transcriptionally regulated by TNF-alpha and identifies a TNF-alpha-responsive region at the 5' flanking sequence of the GS gene.
Chakrabarti
R
R
Department of Molecular Biology and Microbiology and Center for Diagnostics and Drug Development, University of Central Florida, Orlando 32816, USA. rchak@pegasus.cc.ucf.edu
D000818:Animals; D002460:Cell Line; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics*; D017930:Genes, Reporter / Q000235:genetics; D005974:Glutamate-Ammonia Ligase / Q000235:genetics*; D018482:Muscle, Skeletal / Q000201:enzymology; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D015533:Transcriptional Activation / Q000235:genetics; D014162:Transfection / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D015500:Chloramphenicol O-Acetyltransferase; D005974:Glutamate-Ammonia Ligase