| Autor: |
Brown, Robert T., Ades, Ibrahim Z., Nordan, Richard P. |
| Zdroj: |
Journal of Biological Chemistry; December 1995, Vol. 270 Issue: 52 p31129-31135, 7p |
| Abstrakt: |
The immediate early gene, junB, is induced by interleukin-6 (IL-6) in plasmacytomas. In order to identify enhancers that mediate this effect, we cloned upstream and downstream sequences flanking the gene into a luciferase reporter gene vector containing the junBpromoter and evaluated the IL-6 inducibility of these sequences by transient expression in an IL-6-dependent plasmacytoma cell line. Although a 6.5-kilobase fragment of upstream flanking sequence did not increase the IL-6 inducibility of the junBpromoter, a 222-base pair fragment was identified in 2.1 kilobases of downstream flanking sequence that both up-regulates the promoter and confers inducibility by IL-6. Point mutation of an acute phase response factor (APRF) site within this region significantly reduced up-regulation of the promoter in cells grown continuously in IL-6, as well as inducibility upon restimulation of cells with IL-6 after withdrawal from the growth factor. Point mutation of an NF-κB site sharing five nucleotides with the APRF site reduced up-regulation of the promoter but not inducibility by IL-6, whereas mutation of two other NF-κB sites in the 222-base pair fragment had no effect on expression. Western blotting of nuclear proteins purified by DNA affinity chromatography revealed inducible binding of Stat3 and constitutive binding of NF-κB p65 to the APRF/NF-κB site. |
| Databáze: |
Supplemental Index |
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