Maloney Bryan, Ge Yuan-Wen, Alley George M, Lahiri Debomoy K
Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
J Neurochem. 2007 Nov;103(3):1237-57. doi: 10.1111/j.1471-4159.2007.04831.x. Epub 2007 Sep 8.
Apolipoprotein E (ApoE), encoded by the apolipoprotein E gene (APOE), plays an important role in the pathogenesis of Alzheimer's disease (AD). The APOE epsilon4 variant is strongly associated with AD. APOE promoter polymorphisms have also been reported to associate with higher AD risk. Mouse models of APOE expression have long been used to study the pathogenesis of AD. Elucidating the role of the APOE gene in AD requires understanding of how its regulation differs between mouse and human APOE genes, and how the differences influence AD risk. We compared the structure and function of both the human APOE gene promoter (hAPOEP) and mouse APOE gene promoter (mAPOEP) regions. Homology is less than 40% at 180 bp or more upstream of the two species' transcription start site (TSS, +1). Functional analysis revealed both similarities and important differences between the two sequences, significantly affected by human versus rodent cell line origin. We likewise probed nuclear extracts from several cell lines of different origins (astrocytic, glial, and neuronal) and mouse brain with specific hAPOEP and mAPOEP fragments. Each fragment shared DNA-protein interactions with the other but, notably, also bound distinct factors, demonstrated by gel shift and southwestern analyses. We determined possible identities for these distinct factors. These results suggest that regulation of mouse and human APOE genes may be sufficiently unique to justify the use of both the human APOE promoter sequence in transgenic rodent models and non-rodent AD models for studying factors involved in AD pathogenesis.
载脂蛋白E（ApoE）由载脂蛋白E基因（APOE）编码，在阿尔茨海默病（AD）的发病机制中起重要作用。APOE ε4变体与AD密切相关。据报道，APOE启动子多态性也与更高的AD风险相关。长期以来，APOE表达的小鼠模型一直用于研究AD的发病机制。阐明APOE基因在AD中的作用需要了解其在小鼠和人类APOE基因之间的调控差异，以及这些差异如何影响AD风险。我们比较了人类APOE基因启动子（hAPOEP）和小鼠APOE基因启动子（mAPOEP）区域的结构和功能。在两个物种转录起始位点（TSS，+1）上游180 bp或更多处，同源性低于40%。功能分析揭示了这两个序列之间的相似性和重要差异，受人类与啮齿动物细胞系来源的显著影响。我们同样用特定的hAPOEP和mAPOEP片段探测了来自不同来源（星形细胞、神经胶质细胞和神经元）的几种细胞系的核提取物以及小鼠脑。每个片段与另一个片段共享DNA-蛋白质相互作用，但值得注意的是，也结合了不同的因子，凝胶迁移和蛋白质免疫印迹分析证明了这一点。我们确定了这些不同因子可能的身份。这些结果表明，小鼠和人类APOE基因的调控可能足够独特，足以证明在转基因啮齿动物模型和非啮齿动物AD模型中使用人类APOE启动子序列来研究AD发病机制中涉及的因子是合理的。
