INTERLEUKIN-6 INDUCES THE (2'-5')OLIGOADENYLATE SYNTHETASE GENE IN M1 CELLS THROUGH AN EFFECT ON THE INTERFERON-RESPONSIVE ENHANCER

Interleukin-6 (IL-6) activates (2′-5′) A synthetase (2′-5′AS) gene expression in differentiating myeloleukemic M1 cells. Antibodies to type I interferon (IFN) inhibit 2′-5′AS induction but not differentiation. Analysis of the mechanism of 2′-5′AS induction shows that it does not result from increased IFN formation, but from a synergism between IL-6 and endogenously secreted IFN. IL-6 can activate expression of a CAT construct fused to the interferon response sequence (IRS) of the 2′-5′AS gene. In extracts of IL-6-treated M1 cells, changes in protein binding to IRS DNA can be demonstrated. One of the effects of IL-6 on M1 cells is, therefore, to induce DNA binding factors, some of which act on the same enhancer sequence as IFNs, resulting in a synergistic gene activation. M1 variants resistant to differentiation by IL-6 have lost the ability to induce the 2′-5′AS gene. © 1991.