Hu Q, Kukull W A, Bressler S L, Gray M D, Cam J A, Larson E B, Martin G M, Deeb S S
Department of Pathology, University of Washington, Seattle 98195, USA.
Hum Genet. 1998 Sep;103(3):295-303. doi: 10.1007/s004390050820.
The FE65 protein binds to the intracellular domain of the beta-amyloid precursor protein (betaPP) and may modulate the internalization of betaPP. This gene is highly expressed in regions of the brain specifically affected in dementia of the Alzheimer type (DAT). As a prelude to further investigations of the role of FE65 in the metabolism of betaPP and in the pathogenesis of DAT, we have determined the entire genomic structure and sequence of human FE65 and have discovered several polymorphisms in this gene. Human FE65 contains 14 exons ranging in size from 6 to 735 bp. All splice sites conform to consensus sequences except for the donor site of intron 10. The 5' end of FE65 mRNA was identified by rapid amplification of the cDNA 5' end and is 31 bp longer than the previously published cDNA sequence. The 5'-flanking region of this gene is TATA-less and is very GC-rich with at least five putative Sp1 binding sites. In comparison to the genomic rat FE65 sequence, the human FE65 5'-untranslated region is 134 bp longer and has an extra exon (exon 1, 86 bp). To identify mutations/polymorphisms of the coding regions of this gene, we performed blinded analysis of 457 Caucasian case-control samples from a large epidemiological study of sporadic DAT. Screening was conducted by single-strand conformation polymorphism. Four minor variants were found within the coding region, with frequencies between 0.002 and 0.015; two of the four result in amino acid substitutions. The more informative biallelic polymorphism (a trinucleotide deletion and a single base substitution) was found within intron 13 (84 bp), which interrupts two exons encoding the betaPP binding site. The frequency of the minor allele in this intron was 0.097 in DAT cases and 0.161 in controls (chi2=7.78, P=0.0054). Having at least one copy of the minor allele was associated with a decreased risk for DAT (chi2=9.20, P<0.005, odds ratio=0.49, 95% CI 0.31-0.77). Multivariate analysis showed that this association was independent of the APOE genotype. These results suggest that either FE65 itself or a closely linked gene influences the pathogenesis of sporadic DAT. The interaction of FE65 with betaPP and the association of a FE65 polymorphism with DAT lend credence to the hypothesis that the metabolism of betaPP is central to the pathogenesis of common sporadic forms of DAT.
FE65蛋白与β-淀粉样前体蛋白（βPP）的细胞内结构域结合，并可能调节βPP的内化。该基因在阿尔茨海默病型痴呆（DAT）中受特异性影响的脑区中高度表达。作为进一步研究FE65在βPP代谢及DAT发病机制中作用的前奏，我们已确定了人类FE65的完整基因组结构和序列，并在该基因中发现了几种多态性。人类FE65包含14个外显子，大小从6到735 bp不等。除了第10号内含子的供体位点外，所有剪接位点均符合共有序列。通过cDNA 5'末端的快速扩增鉴定了FE65 mRNA的5'末端，其比先前发表的cDNA序列长31 bp。该基因的5'侧翼区无TATA盒，富含GC，至少有五个推定的Sp1结合位点。与基因组大鼠FE65序列相比，人类FE65的5'非翻译区长134 bp，并且有一个额外的外显子（外显子1，86 bp）。为了鉴定该基因编码区的突变/多态性，我们对来自散发性DAT大型流行病学研究的457例白种人病例对照样本进行了盲法分析。通过单链构象多态性进行筛查。在编码区内发现了四个次要变体，频率在0.002至0.015之间；四个中的两个导致氨基酸替换。在第13号内含子（84 bp）内发现了信息量更大的双等位基因多态性（一个三核苷酸缺失和一个单碱基替换），其中断了两个编码βPP结合位点的外显子。该内含子中次要等位基因的频率在DAT病例中为0.097，在对照中为0.161（χ2 = 7.78，P = 0.0054）。拥有至少一个次要等位基因拷贝与DAT风险降低相关（χ2 = 9.20，P <0.005，优势比= 0.49，95％CI 0.31 - 0.77）。多变量分析表明，这种关联独立于APOE基因型。这些结果表明，要么是FE65本身，要么是一个紧密连锁的基因影响散发性DAT的发病机制。FE65与βPP的相互作用以及FE65多态性与DAT的关联支持了βPP代谢是常见散发性DAT发病机制核心的假说。
