PROMOTER ELEMENTS IN THE TRANSCRIPTIONAL ACTIVATION OF THE HUMAN STROMELYSIN-1 GENE BY THE INFLAMMATORY CYTOKINE, INTERLEUKIN-1

Stromelysin-1, a tissue-remodelling metalloproteinase synthesized by f ibroblasts, has proteolytic activity against a variety of extracellula r matrix components. Stromelysin-1 gene transcription is induced by th e inflammatory cytokine interleukin (IL)-1. In fibroblasts transiently transfected with constructs containing 5'-deletion mutants of the hum an stromelysin-1 gene promoter, IL-1-induced transcriptional activity was abolished with the removal of region -102 to -54. This region incl udes an AP-1 binding site at positions -70 to -64. The AP-1 site alone increased the basal activity of and conferred minimal IL-1 inducibili ty onto the heterologous gene promoter of thymidine kinase. Interestin gly, although the removal of the AP-1 site from the native promoter (- 1303 to +4) affected the absolute levels of IL-1-induced and basal pro moter activity, it did not alter their ratio, indicating the involveme nt of regions outside the AP-1 site in the IL-1 response. Of the strom elysin-1 5' flanking sequence examined, only the region -274 to -54 co uld confer IL-1 inducibility to a heterologous promoter independently of the AP-1 site. This region also bound specific nuclear factors. Fur ther analysis revealed that the region composed of -86 to -71 and -63 to -54 could independently respond to IL-1 and bind protein of whole c ell extracts. Protein binding to this region and to the AP-1 site was modestly induced by IL-1 treatment. From these results we conclude tha t, in fibroblasts, the AP-1 site (-70 to -64) is not necessary for the IL-1 response; however, it probably interacts through protein associa tions with the responsive region immediately surrounding it in the abs olute transcriptional activation of the human stromelysin-1 gene by IL -1.