Feng Yong-Qing, Warin Renaud, Li Taihao, Olivier Emmanuel, Besse Arnaud, Lobell Amanda, Fu Haiqing, Lin Chii Mei, Aladjem Mirit I, Bouhassira Eric E
Division of Hematology, Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461, USA.
Mol Cell Biol. 2005 May;25(10):3864-74. doi: 10.1128/MCB.25.10.3864-3874.2005.
Using recombinase-mediated cassette exchange to test multiple transgenes at the same site of integration, we demonstrate a novel chromatin context-dependent silencer activity of the beta-globin locus control region (LCR). This silencer activity requires DNase I hypersensitive sites HS2 and HS3 but not HS4. After silencing, the silenced cassettes adopt a typical closed chromatin conformation (histone H3 and H4 deacetylation, histone H3-K4 methylation, DNA methylation, and replication in late S phase). In the absence of the LCR at the same site of integration, the chromatin remains decondensed. We demonstrate that the LCR is necessary but not sufficient to trigger these chromatin changes. We also provide evidence that this novel silencing activity is caused by transcriptional interference triggered by activation of transcription in the flanking sequences by the LCR.
利用重组酶介导的盒式交换在同一整合位点测试多个转基因，我们证明了β-珠蛋白基因座控制区（LCR）一种新的染色质背景依赖性沉默活性。这种沉默活性需要DNase I超敏位点HS2和HS3，但不需要HS4。沉默后，沉默的盒式结构呈现典型的紧密染色质构象（组蛋白H3和H4去乙酰化、组蛋白H3-K4甲基化、DNA甲基化以及在S期后期复制）。在同一整合位点没有LCR的情况下，染色质保持松散状态。我们证明LCR是引发这些染色质变化所必需的，但并不充分。我们还提供证据表明，这种新的沉默活性是由LCR激活侧翼序列中的转录引发的转录干扰所导致的。
