LIPOPOLYSACCHARIDE INDUCTION OF TISSUE FACTOR EXPRESSION IN THP-1 MONOCYTIC CELLS - PROTEIN-DNA INTERACTIONS WITH THE PROMOTER

Tissue factor, the cellular receptor for factor VII/VIIa, activates bo th the intrinsic and extrinsic pathways of blood coagulation. In this analysis we have used DNase I footprinting to map the sites of protein -DNA interaction along the promoter (-383 to +8) using nuclear extract s prepared from uninduced and lipopolysaccharide-induced THP-1 cells. We have identified six regions that interact with nuclear factors in b oth uninduced and induced extracts. Four footprints are contained with in a region reported to confer base-line high level expression and lip opolysaccharide and serum induction. Two additional footprints map to a region reported to reduce basal transcription by 50%. The only quali tative change in the footprint pattern with uninduced and induced extr acts is the appearance of two hypersensitive sites with uninduced extr acts. In addition, changes in the level of protein- DNA binding are de tected with only one probe by DNA mobility shift analysis. A combinati on of well characterized transcription factors (AP1), primarily lympho id cell specific regulatory proteins (NF-kappaB- and/or Ets-1-related proteins), as well as additional, uncharacterized proteins appear to i nteract with these sequences. Our data suggest that post-translational modification of existing transcription factors, and not induction of new DNA-binding activity, mediates the lipopolysaccharide induction of tissue factor synthesis in THP-1 cells.