Direct interaction of NF-E2 with hypersensitive site 2 of the β-globin locus control region in living cells
Direct interaction of NF-E2 with hypersensitive site 2 of the β-globin locus control region in living cells
复制标题
DOI：
10.1182/blood.v96.1.334.013k17_334_339
复制
发表时间：
2000-07-01
期刊：
影响因子：
20.3
通讯作者：
Bresnick, EH
中科院分区：
文献类型：
--
作者：
Forsberg, EC;Downs, KM;Bresnick, EH
人β-珠蛋白基因座控制区（LCR）赋予β-珠蛋白基因高水平的组织特异性表达。LCR的超敏位点2（HS 2）亚区内的串联Maf识别元件（MARE）对于LCR的强增强子活性是重要的。多种蛋白能够在体外与这些位点相互作用，包括红系细胞和巨核细胞特异性转录因子NF-E2。NF-E2对B-珠蛋白基因表达的重要性在缺乏NF-E2的p45亚基的鼠红白血病细胞中是明显的。这些CB 3细胞在α-和β-珠蛋白基因转录中具有严重缺陷，其可以通过NF-E2的表达来恢复。然而，p45缺失的小鼠表达接近正常水平的β-珠蛋白。因此，在小鼠中存在可以功能性地替代NF-E2的冗余因子，或者NF-E2不通过LCR来调节β-珠蛋白基因表达。为了解决这个问题，我们询问了NF-E2是否直接结合完整细胞中HS 2的串联MARE。使用染色质免疫沉淀试验，我们提供的证据表明，NF-E2直接和特异性结合HS 2在活的红白血病细胞和小鼠胎肝。HS 2序列的特异性免疫分离依赖于p45的存在和HS 2内完整的MARE。这些结果支持NF-E2通过激活LCR在β-珠蛋白基因表达调节中的直接作用。（血。2000;96：334-339）（C）2000由美国血液学学会。
The human beta-globin locus control region (LCR) confers high-level, tissue-specific expression to the beta-globin genes. Tandem Maf recognition elements (MAREs) within the hypersensitive site 2 (HS2) subregion of the LCR are important for the strong enhancer activity of the LCR. Multiple proteins are capable of interacting with these sites in vitro, including the erythroid cell- and megakaryocyte-specific transcription factor, NF-E2. The importance of NF-E2 for B-globin gene expression is evident in murine erythroleukemia cells lacking the p45 subunit of NF-E2. These CB3 cells have a severe defect in alpha- and beta-globin gene transcription, which can be restored by expression of NF-E2. However, mice nullizygous for p45 express nearly normal levels of beta-globin. Thus, either a redundant factor(s) exists in mice that can functionally replace NF-E2, or NF-E2 does not function through the LCR to regulate beta-globin gene expression. To address this issue, we asked whether NF-E2 binds directly to the tandem MAREs of HS2 in intact cells. Using a chromatin immunoprecipitation assay, we provide evidence for NF-E2 binding directly and specifically to HS2 in living erythroleukemia cells and in mouse fetal liver. The specific immunoisolation of HS2 sequences was dependent on the presence of p45 and on intact MAREs within HS2. These results support a direct role for NF-E2 in the regulation of beta-globin gene expression through activation of the LCR. (Blood. 2000;96:334-339) (C) 2000 by The American Society of Hematology.