Transcription of the HS2 enhancer toward a cis-linked gene is independent of the orientation, position, and distance of the enhancer relative to the gene
Transcription of the HS2 enhancer toward a cis-linked gene is independent of the orientation, position, and distance of the enhancer relative to the gene
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DOI：
10.1128/mcb.17.7.3955
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发表时间：
1997-07-01
影响因子：
5.3
通讯作者：
Tuan, D
中科院分区：
文献类型：
--
作者：
Kong, SM;Bohl, D;Tuan, D
基因座控制区（LCR）调控下游10 ~ 50 kb的β-珠蛋白基因的转录。在红系细胞中定义LCR的超敏位点HS 4、-3、-2和-1中，HS 2具有显著的增强子功能。HS 2增强子和LCR的其他功能成分的作用机制尚不清楚，我们用逆转录-PCR和RNA酶保护试验分析了内源性和转染的HS 2增强子在红系K562细胞中的转录状态，观察到一种新的HS 2增强子转录模式，内源性HS 2增强子主要向下游珠蛋白基因方向转录，转染的重组氯霉素乙酰转移酶（CAT）质粒中的HS 2增强子也主要向CAT基因方向转录，而不管增强子是否被置于（i）基因组或反向基因组方向，（ii）基因的5 ′或3 ′位置，或（iii）距基因最多6 kb的各种距离。HS 2增强子在基因向性转录中的方向、位置和距离独立性与观察到的HS 2增强子功能的方向、位置和距离独立性相关，表明增强子转录可能在增强子功能中起作用。
The locus control region (LCR) regulates transcription of the downstream beta-like globin genes 10 to 50 kb away, Among hypersensitive sites HS4, -3, -2, and -1, which define the LCR in erythroid cells, HS2 possesses prominent enhancer function. The mechanism by which the HS2 enhancer and other functional components of the LCR act over the distance is not clear, We have used reverse transcription-PCR and RNase protection assays to analyze the transcriptional statuses of both the endogenous and the transfected HS2 enhancer in erythroid K562 cells, A novel pattern of HS2 enhancer transcription was observed, The endogenous HS2 enhancer was transcribed predominantly in the direction toward the downstream globin genes, The HS2 enhancer in transfected recombinant chloramphenicol acetyltransferase (CAT) plasmids was also transcribed predominantly toward the CAT gene, regardless of whether the enhancer was placed (i) in the genomic or reverse genomic orientation, (ii) in a position 5' or 3' to the gene, or (iii) at various distances up to 6 kb from the gene. The orientation, position, and distance independence in gene-tropic transcription of the HS2 enhancer correlates with the observed orientation, position, and distance independence of HS2 enhancer function and suggests that enhancer transcription may play a role in enhancer function.