Du Yansheng, Chen Xianming, Wei Xing, Bales Kelly R, Berg David T, Paul Steven M, Farlow Martin R, Maloney Bryan, Ge Yuan-Wen, Lahiri Debomoy K
Department of Neurology, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
Brain Res Mol Brain Res. 2005 May 20;136(1-2):177-88. doi: 10.1016/j.molbrainres.2005.02.001.
The apolipoprotein E gene (APOE) plays an important role in the pathogenesis of Alzheimer's disease (AD), and amyloid plaque comprised mostly of the amyloid-beta peptide (A(beta)) is one of the major hallmarks of AD. However, the relationship between these two important molecules is poorly understood. We examined how A(beta) treatment affects APOE expression in cultured cells and tested the role of the transcription factor NF-(kappa)B in APOE gene regulation. To delineate NF-(kappa)B's role, we have characterized a 1098 nucleotide (nt) segment containing the 5'-flanking region of the human APOE gene (-1054/+44, +1 transcription start site). Sequence analysis of this region suggests the presence of two potential NF-(kappa)B elements. To demonstrate promoter activity, the region was cloned upstream of a promoterless luciferase (reporter) gene. This segment was able to drive expression of luciferase in transient transfections of human fetal glial cells. Promoter activity was stimulated twofold by A(beta)(1-40) (25 microM, 24 h) treatment. Pretreatment with double-stranded DNA decoy oligonucleotides against NF-(kappa)B (2 microM) reduced A(beta) stimulation. Deletion and mutagenetic analyses demonstrated that the distal NF-(kappa)B element was functional and showed a strong DNA-protein complex band in gel shift analysis, similar to that from control NF-(kappa)B consensus element. An anti-inflammatory and anti-NF-(kappa)B drug, sodium salicylate, significantly blocked A(beta)-induced APOE promoter function. Our data provide evidence that upregulation of APOE by A(beta) in astroglial cells is mediated by an NF-(kappa)B-element present in the 5'-flanking region of the APOE gene.
载脂蛋白E基因（APOE）在阿尔茨海默病（AD）的发病机制中起重要作用，而主要由β淀粉样肽（Aβ）组成的淀粉样斑块是AD的主要特征之一。然而，这两个重要分子之间的关系却知之甚少。我们研究了Aβ处理如何影响培养细胞中APOE的表达，并测试了转录因子NF-κB在APOE基因调控中的作用。为了阐明NF-κB的作用，我们鉴定了一个包含人类APOE基因5'侧翼区（-1054 / +44，+1转录起始位点）的1098个核苷酸（nt）片段。该区域的序列分析表明存在两个潜在的NF-κB元件。为了证明启动子活性，将该区域克隆到无启动子的荧光素酶（报告）基因上游。该片段能够在人胎儿神经胶质细胞的瞬时转染中驱动荧光素酶的表达。用Aβ（1-40）（25μM，24小时）处理可使启动子活性提高两倍。用针对NF-κB的双链DNA诱饵寡核苷酸（2μM）预处理可降低Aβ刺激。缺失和诱变分析表明，远端NF-κB元件具有功能，并且在凝胶迁移分析中显示出强的DNA-蛋白质复合物条带，类似于来自对照NF-κB共有元件的条带。一种抗炎和抗NF-κB药物水杨酸钠可显著阻断Aβ诱导的APOE启动子功能。我们的数据提供了证据，表明Aβ在星形胶质细胞中对APOE的上调是由APOE基因5'侧翼区存在的NF-κB元件介导的。
