Arbini A A, Pollak E S, Bayleran J K, High K A, Bauer K A
Department of Medicine, Brockton-West Roxbury Department of Veterans Affairs Medical Center, MA, USA.
Blood. 1997 Jan 1;89(1):176-82.
Although small deletions, splice site abnormalities, missense, and nonsense mutations have been identified in patients with factor VII deficiency, there have been no reports of mutations in the factor VII promoter. We investigated a girl with factor VII levels that were less than 1% of normal in association with a severe bleeding diathesis. The patient is homozygous for a T to G transversion that occurs 61 bp before the translation start site. This nucleotide is in a sequence that is an hepatocyte nuclear factor 4 (HNF-4) binding site within the factor VII promoter (ACTTTG AE-->ACGTTG). Using gel mobility shift assays, we show that the mutation disrupts the binding of HNF-4 to its cognate binding site. In growth hormone reporter gene assays, the activity of a plasmid containing the mutant promoter was 6.7% of the wild-type promoter plasmid. Although HNF-4 was able to transactivate the wild-type factor VII promoter 5.4-fold in HeLa cells, no transactivation could be shown with the mutant promoter. These findings indicate that HNF-4 exerts a major positive regulatory effect on factor VII expression and provides in vivo evidence that binding of this transcription factor is critical for normal factor VII expression.
尽管在凝血因子VII缺乏症患者中已鉴定出小的缺失、剪接位点异常、错义突变和无义突变，但尚未有凝血因子VII启动子突变的报道。我们研究了一名凝血因子VII水平低于正常水平1%且伴有严重出血素质的女孩。该患者在翻译起始位点前61 bp处发生了T到G的颠换，呈纯合状态。该核苷酸位于凝血因子VII启动子内的一个肝细胞细胞核因子4（HNF-4）结合位点序列中（ACTTTG AE-->ACGTTG）。通过凝胶迁移率变动分析，我们发现该突变破坏了HNF-4与其同源结合位点的结合。在生长激素报告基因分析中，含有突变启动子的质粒活性为野生型启动子质粒的6.7%。尽管HNF-4能够在HeLa细胞中将野生型凝血因子VII启动子反式激活5.4倍，但突变启动子却未显示出反式激活作用。这些发现表明，HNF-4对凝血因子VII的表达发挥着主要的正向调节作用，并提供了体内证据，证明该转录因子的结合对于正常凝血因子VII的表达至关重要。
