Begbie M, Notley C, Tinlin S, Sawyer L, Lillicrap D
Department of Pathology, Queen's University, Kingston, Ontario, Canada.
Thromb Haemost. 2000 Aug;84(2):216-22.
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 NFkappaB binding site. Mutation of the downstream C/EBP site reduces LPS-responsiveness by approximately 50%, while mutation of the NFkappaB binding site completely eliminates LPS-responsiveness. While binding of C/EBPbeta and NFkappaB is still observed in gel retardation studies using acute phase nuclear extracts and a probe containing mutations to the downstream C/EBP site, neither NFkappaB nor C/EBP appear to bind to a probe in which the NFkappaB 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.
凝血因子VIII是人类中的一种急性期蛋白，最近已被证明对白细胞介素-6有转录反应。在本研究中，我们已经证明，人类因子VIII启动子在暴露于细菌脂多糖（LPS）的培养肝细胞中被激活。缺失分析已将因子VIII启动子的LPS反应元件缩小到一个小区域，该区域包含两个C/EBP结合位点和一个相邻的NFκB结合位点。下游C/EBP位点的突变使LPS反应性降低约50%，而NFκB结合位点的突变则完全消除了LPS反应性。虽然在使用急性期核提取物和含有下游C/EBP位点突变的探针的凝胶阻滞研究中仍观察到C/EBPβ和NFκB的结合，但NFκB和C/EBP似乎都不与NFκB位点已突变的探针结合。在对炎症刺激作出反应时因子VIII水平会升高的物种中，因子VIII启动子的这一区域的保守性表明，这些转录因子结合位点对于应激条件下因子VIII基因的正常调控很重要。
