Developmental stage differences in chromatin subdomains of the β-globin locus
Developmental stage differences in chromatin subdomains of the β-globin locus
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DOI：
10.1073/pnas.0307985101
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发表时间：
2004-05-04
影响因子：
11.1
通讯作者：
Dean, A
中科院分区：
文献类型：
--
作者：
Kim, A;Dean, A
每个哺乳动物β-珠蛋白基因座都包含一个发育表达基因家族，以及一个远上游调控元件，即基因座控制区（LCR）。在成年鼠红系细胞中，LCR和转录的β-珠蛋白基因存在于组蛋白乙酰化的结构域内，RNA聚合酶II（pol II）与它们相关。相反，沉默的胚胎基因位于低乙酰化染色质中的这些结构域之间，并且在那里没有发现pol 11。我们使用染色质免疫沉淀和实时PCR来分析表达胚胎E-球蛋白基因但不表达成人β-球蛋白基因的人红系K562细胞中组蛋白修饰和pol 11向球蛋白基因座的募集。H3和H4乙酰化和H3 K4甲基化在包括LCR和活性E-珠蛋白基因的17-kb区域上是连续的。修饰的水平直接随E-珠蛋白基因的转录而变化。相比之下，非红系HeLa细胞中的该区域缺乏这些修饰，而是显示广泛的H3 K9甲基化。从LCR到e-珠蛋白基因也连续检测到pol 11。这些研究揭示了染色质结构和pol 11分布的几个方面，区分珠蛋白基因座在胚胎和成人阶段，并表明增强子循环和跟踪机制可能有助于LCR启动子通信在不同的发育阶段。
The mammalian beta-globin loci each contain a family of developmentally expressed genes, and a far upstream regulatory element, the locus control region (LCR). In adult murine erythroid cells, the LCR and the transcribed beta-globin genes exist within domains of histone acetylation and RNA polymerase II (pol II) is associated with them. In contrast, the silent embryonic genes lie between these domains within hypoacetylated chromatin, and pol 11 is not found there. We used chromatin immunoprecipitation and real-time PCR to analyze histone modification and pol 11 recruitment to the globin locus in human erythroid K562 cells that express the embryonic E-globin gene but not the adult beta-globin gene. H3 and H4 acetylation and H3 K4 methylation were continuous over a 17-kb region including the LCR and the active E-globin gene. The level of modification varied directly with the transcription of the E-globin gene. In contrast, this region in nonerythroid HeLa cells lacked these modifications and displayed instead widespread H3 K9 methylation. pol 11 was also detected continuously from the LCR to the e-globin gene. These studies reveal several aspects of chromatin structure and pol 11 distribution that distinguish the globin locus at embryonic and adult stages and suggest that both enhancer looping and tracking mechanisms may contribute to LCR-promoter communication at different developmental stages.