CCAAT/enhancer binding proteins alpha and beta regulate the tumor necrosis factor receptor 1 gene promoter.
CCAAT/enhancer binding protein (C/EBP) transcription factors play essential roles in regulating an array of cellular processes, including differentiation, energy metabolism, and inflammation. In this report we demonstrate that both C/EBPalpha and C/EBPbeta activate the promoter driving transcription of the tumor necrosis factor receptor 1 (TNFR1). TNFR1 is the major receptor for tumor necrosis factor (TNF), a critical cytokine mediator of the inflammatory response. Although the TNFR1 protein has been shown to be regulated through post-translational modifications, very little is known about the transcriptional regulation of the TNFR1 gene. Here we have identified a specific C/EBP binding site within the TNFR1 promoter, and shown that this site is required for both C/EBPalpha and C/EBPbeta activation of the promoter in reporter gene assays. Furthermore, we show that both C/EBPalpha and C/EBPbeta are bound to the TNFR1 promoter in cells using chromatin immunoprecipitation assays. Finally, we demonstrate that reducing the level of C/EBPalpha and C/EBPbeta expression in cells using siRNA technology leads to decreased expression of the TNFR1 protein. These results suggest that the C/EBPalpha and C/EBPbeta transcription factors enhance expression of the TNFR1 protein in cells. Given that TNF and C/EBPbeta are known to activate each other's expression, C/EBPbeta may greatly amplify the initial TNF signal through a positive auto-regulatory mechanism.
Bristol
Jillian A
JA
Departments of Oncology and Medical Microbiology and Immunology, University of Wisconsin School of Medicine and Public Health, Madison, 53706, United States.
Morrison
Thomas E
TE
Kenney
Shannon C
SC
D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000235:genetics / Q000378:metabolism*; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics / Q000378:metabolism; D047369:Chromatin Immunoprecipitation; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D016297:Mutagenesis, Site-Directed; D009841:Oligonucleotides / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding; D034741:RNA, Small Interfering / Q000235:genetics; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014162:Transfection
D022763:CCAAT-Enhancer-Binding Protein-alpha; D022782:CCAAT-Enhancer-Binding Protein-beta; D009841:Oligonucleotides; D034741:RNA, Small Interfering; D047888:Receptors, Tumor Necrosis Factor, Type I; D011993:Recombinant Fusion Proteins; D015500:Chloramphenicol O-Acetyltransferase