GENETIC VARIATION IN APOLIPOPROTEIN E EXPRESSION

来自遗传流行病学研究的数据表明，APOE基因变异与阿尔茨海默病(AD)易感性的关系可能不仅限于已有的编码多态，而且还可能受到DNA两侧的多态的影响。特别是，我们最近观察到APOC1HPAI等位基因与阿尔茨海默病的相关性，在具有“参考”APOE E3/E3基因型的人群中。在这个项目中，我们将进行分子分析和实验来验证APOE侧翼序列影响AD易感性的假设，即这种影响是通过这些多态性对等位基因特异性APOE mRNA表达的影响来实现的。首先，为了测试AD的易感性是否依赖于位于染色体顺式的APOE编码和调控多态的特定组合，我们将开发一种方法来确定APOE启动子、APOE编码区和APOC1启动子中的多态标记的完整单倍型，并将在项目1中讨论的大的多民族人群样本中生成用于AD关联分析的单倍型数据。其次，我们将使用转基因筛选，检测APOE和APOC1启动子中是否存在功能序列多态，我们将确定APOE和APOC1启动子中的功能序列多态序列，我们将确定这些多态的序列，并将它们作为新的标记应用于单倍型分析。第三，我们将通过将个体多态和单倍型与人类淋巴母细胞系以及肝、肾和脑组织中等位基因特异的APOE mRNA水平相关联，来测试它们在体内的功能意义。第四，利用apoCI启动子“敲除”小鼠，我们将测试APOE和APOC1参与增强竞争的模型，以解释观察到的APOC1HPAI等位基因与AD的关联。利用转基因和转基因小鼠，我们还将研究APOE可能的脑增强子的定位，然后寻找该区域的功能多态性。这些研究的结果可能揭示阿尔茨海默病的基本机制，这是可获得的药物干预，也可能揭示在不同种族观察到的明显阿尔茨海默病风险的差异。

Data from genetic epidemiological studies suggest that the involvement of genetic variation at the APOE locus in Alzheimer's disease (AD) susceptibility may not be restricted to the well-studied coding polymorphisms, but may also be influenced by polymorphisms in flanking DNA. In particular, we have recently observed an association of the APOC1 HpaI+ allele with AD in groups of people with the "reference" APOE e3/e3 genotype. In this project we will carry out molecular analyses and experiments to test the hypothesis that APOE flanking sequences influence AD susceptibility is that this effect is through the influence of these polymorphisms on allele-specific APOE mRNA expression. First, to test whether AD susceptibility depends on particular combinations of APOE coding and regulatory polymorphisms located in cis on the chromosome, we will develop a method for determining complete haplotypes of polymorphic markers in the APOE promoter, the APOE coding region and the APOC1 promoter and we will generate haplotype data for AD association analysis in the large multi-ethnic population samples discussed in Project 1. Second, using a transfection assay screen, we will test for the existence of functional sequence polymorphisms in the APOE and APOC1 promoters, we will determine the sequence of functional sequence polymorphisms in the APOE and APOC1 promoters, we will determine the sequence of these polymorphisms in the APOE and APOC1 promoters, we will determine the sequence of these polymorphisms and we will apply them as new markers in the haplotype analyses. Third, we will test for functional significance for the individual polymorphisms and haplotypes in vivo by correlating them with allele-specific APOE mRNA levels in human lymphoblastoid cell lines and liver, kidney and brain tissues. Fourth, using apoCI promoter "knockout" mice, we will test a model in which the APOE and APOC1 engage in enhance-competition as an explanation for the observed association of the APOC1 HpaI+ allele with AD. Using transfections and transgenic mice we will also investigate localization of the putative brain-enhancer of APOE and then search for functional polymorphisms in this region. Results of these studies may reveal a basic mechanism for AD which is accessible to pharmacological intervention and may also shed light on the difference sin apparent AD risk who have been observed in different ethnic groups.