FUNCTIONAL NF-KAPPA-B ELEMENT IN RABBIT SERUM AMYLOID-A GENE AND ITS ROLE IN ACUTE-PHASE INDUCTION

Serum amyloid A (SAA) protein synthesis is highly induced in acute inflammatory conditions. Such induction process is primarily regulated at the transcriptional level and a large amount of SAA mRNA has been found to accumulate in rabbit liver during acute inflammation. To identify the promoter element(s) involved in inducible transcription of SAA, a 5′flanking region of this gene has been fused to a reporter chloramphenicol acetyl transferase (CAT) gene and transfected into BNL liver cells. This DNA is capable of inducing synthesis of the reporter gene in response to lipopolysaccharide-stimulated monocyte-derived conditioned medium. Deletion analyses have shown that a region from -135 to -78 that contains a putative NF-κB element is responsible for the inducible function of the promoter. Gel shift assay has detected DNA-binding activity in the induced cells that appear to interact with the potential NF-κB element located within -112 to -78 of the SAA gene. Similar factor(s) have also been detected in the lipopolysaccharide-treated rabbit liver which is highly active in transcribing SAA mRNA. Appearance of these factors in acute-phase induced animals and their binding to the NF-κB-like element in the SAA proximal promoter region correlated with SAA mRNA synthesis suggests functional role of this promoter element in SAA gene expression under LPS-induced acute-phase condition. © 1993 Academic Press, Inc.