The goal of our project has been the elucidation of the molecular events involved in the regulation of the acute phase response in man. We have concentrated our attention on the prototype acute phase reactant, C-reactive protein (CRP). Our development of an in vitro cell culture system to monitor the induction of acute phase protein synthesis has made it possible not only to determine the extent of de novo CRP synthesis, the type of processing of the protein and the transcriptional level of regulation, but also to determine the types of biological factors responsible for the induction of acute phase reactants. Previously, we found that this protein referred to as B-cell Stimulatory Factor, Interferon-beta 2 or Interleukin-6 is one factor responsible for the induction of CRP in our cell culture system. To a lesser extent leukemia inhibitory factor (HILDA) also has some stimulatory activity. However, we found that Il-6 alone is necessary and sufficient to initiate CRP transcription. We are also determining the cis-acting elements responsible for the regulatory control of acute phase protein gene expression. We have isolated the upstream promoter region for the CRP gene and have shown that this region confers inducibility. We have also identified both positive and negative regulatory proximal IL-6 responsive elements (6RE) flanking a negative regulatory region. Using mobility shift assays and crosslinking, we have identified several physically separated 6REs. These two elements contain the consensus sequence, APTGPNGNAANCTCNC, and bind a constitutive and an inducible factor. In the promoter proximal region there is also AT-rich and Octamer-like sequences which bind factors constitutively and play a role in induction. The constitutive and inducible proteins involved in these specific binding motifs are being characterized.
