NF-KAPPA-B LIKE FACTORS MEDIATE INTERLEUKIN-1 INDUCTION OF C-MYC GENE-TRANSCRIPTION IN FIBROBLASTS

InterLeukin 1 (IL-1) is a pluripotent cytokine involved in mediating a variety of physiological processes, including induction of cell proliferation upon wound healing. Treatment of quiescent FS-4 human dermal fibroblast cells with IL-1 activates c-myc gene transcription, and nuclear localization of NF-kappa-B. Previously, we have noted that the murine c-myc gene contains two functional NF-kappa-B sites located at -1101 to -1081 bp (upstream regulatory element [URE]) and +440 to +459 bp (internal regulatory element [IPE]) relative to the P1 promoter. Here we have demonstrated that IL-1 treatment induced binding of NF-kappa-B-like proteins (p50/p65) to these c-myc elements. Heterologous promoter-CAT constructs driven by multiple copies of either the URE or IRE were IL-1 inducible when transfected into FS-4 cells. In contrast, constructs harboring elements with two G to C residue conversions, such that they were no longer able to bind NF-kappa-B, were not responsive to IL-1. Mutation of these two base pairs at both NF-kappa-B sites within a c-myx promoter/exon I-CAT construct, resulted in loss of inducibility with IL-1 upon transfection into quiescent FS-4 cells. Thus, IL-1 significantly induces c-myc expression through positive regulation by NF-kappa-B, suggesting a role for this family of factors in activation of proliferation associated with wound healing.