Lipopolysaccharide binding protein expression in primary human hepatocytes and HepG2 hepatoma cells
| Autor: | B J, Grube, C G, Cochane, R D, Ye, C E, Green, M E, McPhail, R J, Ulevitch, P S, Tobias |
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| Rok vydání: | 1994 |
| Předmět: |
Lipopolysaccharides
Carcinoma Hepatocellular Membrane Glycoproteins Interleukin-6 Tumor Necrosis Factor-alpha Immunoblotting Liver Neoplasms Dexamethasone Recombinant Proteins Cell Line Liver Gram-Negative Bacteria Tumor Cells Cultured Cytokines Humans Carrier Proteins Cells Cultured Acute-Phase Proteins Interleukin-1 |
| Zdroj: | The Journal of biological chemistry. 269(11) |
| ISSN: | 0021-9258 |
| Popis: | Lipopolysaccharide (LPS)-binding protein (LBP) is a normal plasma protein and an acute phase reactant important for host responses to Gram-negative bacteria and LPS. LBP forms high affinity complexes with LPS which bind to CD14, a monocyte surface protein, to initiate the release of inflammatory mediators. We found that human primary hepatocytes synthesize LBP and that the synthesis is up-regulated by interleukin (IL)-6. To examine this phenomenon in more detail, we evaluated the capacity of IL-6, IL-1, and tumor necrosis factor to induce LBP synthesis in HepG2 cells in the presence or absence of dexamethasone. IL-6 induced LBP synthesis. Dexamethasone, IL-1, and tumor necrosis factor had a synergistic effect when combined with IL-6, but demonstrated minimal effect independently. LBP biosynthesis was evaluated by immunoprecipitation of 35S-labeled LBP from HepG2 supernatants, measurement of steady-state LBP mRNA levels, and analysis of LBP-dependent LPS binding to CD14 positive cells. An 35S-labeled, 60-kDa protein was immunoprecipitated with anti-LBP antibody from IL-6-stimulated HepG2 cell supernatants. Northern blot analysis of cellular RNA revealed an increase in LBP mRNA in IL-6-stimulated cells. CD14 expressing cells bound fluoresceinated LPS in the presence of supernatants from HepG2 cells treated with IL-6. These data provide the first information about specific cytokine and dexamethasone regulation of LBP expression in HepG2 cells. LBP behaves like a Type 1 acute phase protein. |
| Databáze: | OpenAIRE |
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