NF-κB1 (p50) Is Upregulated in Lipopolysaccharide Tolerance and Can Block Tumor Necrosis Factor Gene Expression
| Autor: | Stefan Kastenbauer, H. W. Löms Ziegler-Heitbrock |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
Lipopolysaccharides
Immunology Biology Microbiology Immune tolerance Cell Line Transactivation Genes Reporter Gene expression medicine Immune Tolerance Humans Promoter Regions Genetic Cell Line Transformed Regulation of gene expression Cell Nucleus Host Response and Inflammation Dose-Response Relationship Drug Tumor Necrosis Factor-alpha Monocyte HEK 293 cells NF-kappa B Transcription Factor RelA NF-kappa B p50 Subunit Molecular biology Up-Regulation medicine.anatomical_structure Infectious Diseases Gene Expression Regulation Cell culture Tumor necrosis factor alpha Parasitology |
| Zdroj: | Infection and Immunity. 67:1553-1559 |
| ISSN: | 1098-5522 0019-9567 |
| DOI: | 10.1128/.67.4.1553-1559.1999 |
| Popis: | Monocytes respond to lipopolysaccharide (LPS) stimulation with a rapid expression of the tumor necrosis factor (TNF) gene. Upon repeated LPS stimulation there is, however, little production of TNF mRNA and protein; i.e., the cells are tolerant to LPS. Analysis of NF-κB proteins in gel shift assays demonstrated that the DNA binding activity that is induced by LPS stimulation in tolerant cells consists mainly of p50-p50 homodimers. Since p50 can bind to DNA but lacks a transactivation domain, this may explain the blockade of TNF gene expression. We now show that in the monocytic cell line Mono Mac 6, this inability to respond can be largely ascribed to NF-κB, since a reporter construct directed by a trimeric NF-κB motif is strongly transactivated by LPS stimulation of naive cells whereas LPS-tolerant cells exhibit only low activity. Also, Western blot analyses of proteins extracted from purified nuclei showed mobilization of threefold-higher levels of p50 protein in tolerant compared to naive cells, while mobilization of p65 was unaltered. Overexpression of p50 in HEK 293 cells resulted in a strong reduction of p65-driven TNF promoter activity at the levels of both luciferase mRNA and protein. These data support the concept that an upregulation of p50 is instrumental in LPS tolerance in human monocytes. |
| Databáze: | OpenAIRE |
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