Mouchel Nathalie, Henstra Sytse A, McCarthy Victoria A, Williams Sarah H, Phylactides Marios, Harris Ann
Paediatric Molecular Genetics, Weatherall Institute of Molecular Medicine, Oxford University, John Radcliffe Hospital, Oxford OX3 9DS, UK.
Biochem J. 2004 Mar 15;378(Pt 3):909-18. doi: 10.1042/BJ20031157.
The CFTR (cystic fibrosis transmembrane conductance regulator) gene shows a complex pattern of expression with tissue-specific and temporal regulation. However, the genetic elements and transcription factors that control CFTR expression are largely unidentified. The CFTR promoter does not confer tissue specificity on gene expression, suggesting that there are regulatory elements outside the upstream region. Analysis of potential regulatory elements defined as DNase 1-hypersensitive sites within introns of the gene revealed multiple predicted binding sites for the HNF1alpha (hepatocyte nuclear factor 1alpha) transcription factor. HNF1alpha, which is expressed in many of the same epithelial cell types as CFTR and shows similar differentiation-dependent changes in gene expression, bound to these sites in vitro. Overexpression of heterologous HNF1alpha augmented CFTR transcription in vivo. In contrast, antisense inhibition of HNF1 alpha transcription decreased the CFTR mRNA levels. Hnf1 alpha knockout mice showed lower levels of CFTR mRNA in their small intestine in comparison with wild-type mice. This is the first report of a transcription factor, which confers tissue specificity on the expression of this important disease-associated gene.
囊性纤维化跨膜传导调节因子（CFTR）基因呈现出一种复杂的表达模式，具有组织特异性和时间调控。然而，控制CFTR表达的遗传元件和转录因子在很大程度上尚未明确。CFTR启动子并不赋予基因表达组织特异性，这表明上游区域之外存在调控元件。对该基因内含子中定义为DNase 1高敏位点的潜在调控元件进行分析，发现了多个肝细胞核因子1α（HNF1α）转录因子的预测结合位点。HNF1α在许多与CFTR相同的上皮细胞类型中表达，并在基因表达中表现出类似的分化依赖性变化，在体外能与这些位点结合。异源HNF1α的过表达在体内增强了CFTR转录。相反，HNF1α转录的反义抑制降低了CFTR mRNA水平。与野生型小鼠相比，Hnf1α基因敲除小鼠小肠中的CFTR mRNA水平较低。这是关于一种转录因子的首次报道，该转录因子赋予了这个重要的疾病相关基因表达的组织特异性。
