Summary
Coagulation Factor VIII is an acute phase protein in humans that has recently been
shown to be transcriptionally responsive to interleukin-6. In this study, we have
demonstrated that the human Factor VIII promoter is activated in cultured hepatocytes
exposed to bacterial lipopolysaccharide (LPS). Deletion 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 adjacent NFκB binding site. Mutation of the downstream
C/EBP site reduces LPS-responsiveness by ∼50%, while mutation of the NFκB binding
site completely eliminates LPS-responsiveness. While binding of C/EBPβ and NFκB is
still observed in gel retardation studies using acute phase nuclear extracts and a
probe containing mutations to the downstream C/EBP site, neither NFκB nor C/EBP appear
to bind to a probe in which the NFκB site has been mutated. Conservation of this region
of the Factor VIII promoter in species which exhibit an increase in Factor VIII levels
in response to inflammatory stimuli suggests that these transcription factor binding
sites are important for normal regulation of the Factor VIII gene under conditions
of stress.
Keywords
Factor VIII - inflammation - acute phase - NFκB - C/EBP