Characterization of the chicken beta-globin insulator
Characterization of the chicken beta-globin insulator
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DOI：
10.1073/pnas.94.2.575
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发表时间：
1997-01-21
影响因子：
11.1
通讯作者：
Felsenfeld, G
中科院分区：
文献类型：
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作者：
Chung, JH;Bell, AC;Felsenfeld, G
首先在果蝇中发现的绝缘子是一种DNA序列元件，可以保护启动子免受附近调控元件的影响。我们之前报道过鸡β -珠蛋白位点5'端的DNA序列可以作为绝缘体。在人红白血病细胞系K562中，它能够屏蔽报告基因免受附近小鼠β -珠蛋白位点控制区元件的激活作用。在本报告中，我们发现大部分的绝缘活性位于一个250 bp的CpG岛（核心元件）上，该岛包含构成型DNA酶i超敏位点（5'HS4），与核心序列的DNA结合分析显示出复杂的蛋白质结合模式，当使用串联拷贝时，核心元件的绝缘活性增加。虽然CpG岛通常与管家基因的启动子有关，但我们发现很少有证据表明其核心元件是启动子。此外，绝缘子与启动子的区别在于其定向阻断基因座控制区效应的能力。
Insulators, first identified in Drosophila, are DNA sequence elements that shield a promoter from nearby regulatory elements. We have previously reported that a DNA sequence at the 5' end of the chicken beta-globin locus can function as an insulator. It is capable of shielding a reporter gene from the activating effects of a nearby mouse beta-globin locus control region element in the human erythroleukemic cell line K562. In this report, we show that most of the insulating activity lies in a 250-bp CpG island (core element), which contains the constitutive DNase I-hypersensitive site (5'HS4), DNA binding assays with the core sequence reveal a complex protein binding pattern, The insulating activity of the core element is multiplied when tandem copies are used. Although CpG islands are often associated with promoters of housekeeping genes, we find little evidence that the core element is a promoter, Furthermore, the insulator differs from a promoter in its ability to block the locus control region effect directionally.