The Factor VIII acute phase response requires the participation of NF kappa B and C/EBP

Coagulation Factor VIII is an acute phase protein in humans that has recent ly been shown to be transcriptionally responsive to interleukin-6. In this study, we have demonstrated that the human Factor VIII promoter is activate d in cultured hepatocytes exposed to bacterial lipopolysaccharide (LPS). De letion analysis has narrowed the LPS-responsive element of the Factor VIII promoter to a small region which contains two C/EBP binding sites and an ad jacent NF kappa B binding site. Mutation of the downstream C/EBP site reduc es LPS-responsiveness by similar to 50%, while mutation of the NF kappa B b inding site completely eliminates LPS-responsiveness. While binding of C/EB P beta and NF kappa B is still observed in gel retardation studies using ac ute phase nuclear extracts and a probe containing mutations to the downstre am C/EBP site, neither NF kappa B nor C/EBP appear to bind to a probe in wh ich the NF kappa B site has been mutated. Conservation of this region of th e Factor Vm promoter in species which exhibit an increase in Factor Vm leve ls in response to inflammatory stimuli suggests that these transcription fa ctor binding sites are important for normal regulation of the Factor VIII g ene under conditions of stress.