McCarthy Victoria A, Ott Christopher J, Phylactides Marios, Harris Ann
Paediatric Molecular Genetics, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK.
Biochim Biophys Acta. 2009 Nov-Dec;1789(11-12):709-18. doi: 10.1016/j.bbagrm.2009.09.005. Epub 2009 Sep 24.
The tissue-specific regulation of the cystic fibrosis transmembrane conductance regulator gene (CFTR) is coordinated by intronic and extragenic cis-acting elements that influence its transcriptional activity. The promoter apparently lacks sequences to drive cell type-specific expression. We previously identified a number of intronic elements that were associated with DNase I hypersensitive sites (DHS) and bound the hepatocyte nuclear factor 1 (HNF1) transcription factor. Moreover, we demonstrated the likely involvement of HNF1 in the regulation of CFTR expression in vivo. Here we investigate DHS in introns 16 and 17a of the CFTR gene, which are evident in intestinal and pancreatic cell lines, and determine the transcription factors that interact with these sites. Of particular interest were factors known to interact with HNF1 in coordinated expression of genes in the gastrointestinal tract. We demonstrate that though sequences within these DHS bind HNF1, CDX2, and PBX1 in vitro, only PBX1 show a robust in vivo interaction. These data contribute to our understanding of the complexity of cell-type-specific CFTR regulatory mechanisms.
囊性纤维化跨膜传导调节因子基因（CFTR）的组织特异性调控由影响其转录活性的内含子和顺式作用元件协调。该启动子显然缺乏驱动细胞类型特异性表达的序列。我们之前鉴定了一些与DNA酶I超敏位点（DHS）相关且结合肝细胞核因子1（HNF1）转录因子的内含子元件。此外，我们证明了HNF1可能参与体内CFTR表达的调控。在这里，我们研究了CFTR基因第16和17a内含子中的DHS，这些位点在肠道和胰腺细胞系中很明显，并确定了与这些位点相互作用的转录因子。特别令人感兴趣的是已知在胃肠道基因协调表达中与HNF1相互作用的因子。我们证明，尽管这些DHS内的序列在体外能结合HNF1、CDX2和PBX1，但只有PBX1在体内显示出强烈的相互作用。这些数据有助于我们理解细胞类型特异性CFTR调控机制的复杂性。
