McVey J H, Michaelides K, Hansen L P, Ferguson-Smith M, Tilghman S, Krumlauf R, Tuddenham E G
Haemostasis Research Group, Clinical Research Centre, Harrow, UK.
Hum Mol Genet. 1993 Apr;2(4):379-84. doi: 10.1093/hmg/2.4.379.
A family displaying hereditary persistence of alpha-fetoprotein (HPAFP) in adult life was detected in an antenatal screening programme for spina bifida. RFLP linkage analysis shows that the trait is linked with the albumin-AFP locus. The molecular mechanism responsible for the post-natal repression of the AFP gene is unknown. We wished to determine the molecular mechanism underlying HPAFP in this family. Sequence analysis of the 5'-flanking sequences of their gene revealed a GA substitution at position -119 associated with the trait. This substitution occurs in a potential HNF I binding site, and increases the similarity of the sequence to a consensus HNF I recognition site. In a competitive gel retardation assay the mutant sequence binds HNF I alpha more tightly than the wild type sequence. Furthermore, 5'-flanking sequences of the human AFP gene containing the G-->A substitution direct a higher level of CAT expression in transfected human hepatoma cells than the wild type sequences. We conclude that the G-->A substitution at position -119 of the AFP gene is the mutation causing HPAFP in this family. These results highlight the importance of this HNF I binding site in the developmental regulation of the AFP gene.
在一项针对脊柱裂的产前筛查项目中，检测到一个在成年期表现出甲胎蛋白遗传性持续存在（HPAFP）的家族。限制性片段长度多态性（RFLP）连锁分析表明，该性状与白蛋白 - 甲胎蛋白基因座连锁。负责甲胎蛋白基因产后抑制的分子机制尚不清楚。我们希望确定这个家族中HPAFP的分子机制。对其基因5'侧翼序列的分析显示，在 -119 位存在一个与该性状相关的GA替换。这种替换发生在一个潜在的肝细胞核因子1（HNF I）结合位点，并且增加了该序列与HNF I共有识别位点的相似性。在竞争性凝胶阻滞试验中，突变序列比野生型序列更紧密地结合HNF Iα。此外，含有G→A替换的人甲胎蛋白基因5'侧翼序列在转染的人肝癌细胞中指导的氯霉素乙酰转移酶（CAT）表达水平比野生型序列更高。我们得出结论，甲胎蛋白基因 -119 位的G→A替换是导致这个家族出现HPAFP的突变。这些结果突出了这个HNF I结合位点在甲胎蛋白基因发育调控中的重要性。
