Ray B K, Ray A
Department of Veterinary Microbiology, College of Veterinary Medicine, University of Missouri, Columbia 65211.
Biochem Biophys Res Commun. 1993 Jun 30;193(3):1159-67. doi: 10.1006/bbrc.1993.1747.
Serum amyloid A (SAA) protein synthesis is highly induced in acute inflammatory conditions. Such induction process is primarily regulated at the transcriptional level and 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-kappa B 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-kappa B 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-kappa B-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.
血清淀粉样蛋白A（SAA）的蛋白质合成在急性炎症条件下会被高度诱导。这种诱导过程主要在转录水平上受到调控，并且已发现大量SAA mRNA在急性炎症期间在兔肝脏中积累。为了鉴定参与SAA诱导性转录的启动子元件，该基因的5'侧翼区域已与报告氯霉素乙酰转移酶（CAT）基因融合，并转染到BNL肝细胞中。这种DNA能够响应脂多糖刺激的单核细胞衍生的条件培养基诱导报告基因的合成。缺失分析表明，包含推定的NF-κB元件的-135至-78区域负责启动子的诱导功能。凝胶迁移试验检测到诱导细胞中的DNA结合活性，该活性似乎与位于SAA基因-112至-78内的潜在NF-κB元件相互作用。在转录SAA mRNA高度活跃的脂多糖处理的兔肝脏中也检测到了类似的因子。这些因子在急性期诱导动物中的出现及其与SAA近端启动子区域中NF-κB样元件的结合与SAA mRNA合成相关，表明该启动子元件在LPS诱导的急性期条件下SAA基因表达中具有功能作用。
