INTERLEUKIN-1 INDUCTION OF THE C-JUN PROMOTER

Interleukin 1 (IL-1) induces pleiotropic effects in many cell types du ring inflammation and immunity. We have recently shown how the IL-1 si gnal is transmitted to the nucleus: In T cells and in pituitary cells, IL-1 induced genes via activation of the nuclear factor AP-1. We now demonstrate how IL-1 activates the AP-1 factor in liver cells, which a re a major target for IL-1 during the acute phase response in vivo. IL -1 induced gene transcription of both AP-1 components, c-jun and c-fos . IL-1 also increased the stability of c-jun mRNA. We define two enhan cer sites in the jun promoter that are required for induction by IL-1. Although the binding sites share some similarity with the AP-1 bindin g site, the nuclear factors binding the jun motifs are not composed of Jun or Fos proteins. Thus these data identify two binding proteins th at serve as one of the first nuclear targets for IL-1 signal transduct ion.