CTCF mediates insulator function at the CFTR locus
CTCF mediates insulator function at the CFTR locus
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DOI：
10.1042/bj20070429
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发表时间：
2007-12-01
影响因子：
4.1
通讯作者：
Harris, Ann
中科院分区：
文献类型：
--
作者：
Blackledge, Neil P.;Carter, Emma J.;Harris, Ann
位于基因基础启动子之外的调控元件可以通过染色质结构和组蛋白修饰的局部变化来揭示。 CFTR（囊性纤维化跨膜电导调节因子）基因的启动子与其复杂的表达模式无关。为了确定 CFTR 的重要调控元件，我们之前绘制了跨越基因座 400 kb 的 DHS（DNase I 超敏感位点）。特别令人感兴趣的是 CFTR 基因侧翼的两个 DHS，相对于翻译起始位点而言位于上游 -20.9 kb 处，下游位于 + 15.6 kb 处。在本研究中，我们证明这两种 DHS 具有增强子阻断活性并结合已知绝缘体元件特征的蛋白质。 - 20.9 kb 处的 DHS 核心在体外和体内均能结合 CTCF（CCCTC 结合因子）；然而，+15.6 kb 核心似乎与其他因素结合。 CFTR 位点的组蛋白修饰分析突出了 - 20.9 kb 和 + 15.6 kb DHS 之间的结构差异，进一步表明这两个绝缘体元件可能通过不同的机制起作用。我们建议这两个 DHS 标记 CFTR 基因功能单元的边界，并建立一个染色质结构域，在该结构域内维持 CFTR 表达的复杂特征。
Regulatory elements that lie outside the basal promoter of a gene may be revealed by local changes in chromatin structure and histone modifications. The promoter of the CFTR (cystic fibrosis transmembrane conductance regulator) gene is not responsible for its complex pattern of expression. To identify important regulatory elements for CFTR we have previously mapped DHS (DNase I-hypersensitive sites) across 400 kb spanning the locus. Of particular interest were two DHS that flank the CFTR gene, upstream at -20.9 kb with respect to the translational start site, and downstream at + 15.6 kb. In the present study we show that these two DHS possess enhancer-blocking activity and bind proteins that are characteristic of known insulator elements. The DHS core at - 20.9 kb binds CTCF (CCCTC-binding factor) both in vitro and in vivo; however, the + 15.6 kb core appears to bind other factors. Histone-modification analysis across the CFTR locus highlights structural differences between the - 20.9 kb and + 15.6 kb DHS, further suggesting that these two insulator elements may operate by distinct mechanisms. We propose that these two DHS mark the boundaries of the CFTR gene functional unit and establish a chromatin domain within which the complex profile of CFTR expression is maintained.