The beta-globin locus control region enhances transcription of but does not confer position-independent expression onto the lacZ gene in transgenic mice
The beta-globin locus control region enhances transcription of but does not confer position-independent expression onto the lacZ gene in transgenic mice
复制标题
DOI：
10.1002/j.1460-2075.1996.tb00741.x
复制
发表时间：
1996-07-15
期刊：
影响因子：
11.4
通讯作者：
Wall, L
中科院分区：
文献类型：
--
作者：
Guy, LG;Kothary, R;Wall, L
β-珠蛋白基因座控制区 (LCR) 赋予珠蛋白转基因高水平的位置无关、拷贝数依赖性表达。这里研究了> 40个独立的转基因小鼠品系和创始者，它们以顺式方式携带有驱动lacZ报告基因的β-珠蛋白基因启动子的LCR，通过测量胎儿肝脏提取物中的β-半乳糖苷酶活性来测定lacZ转基因的表达，其水平与使用RNase保护测定法测定的lacZ mRNA的量相关。出乎意料的是，发现lacZ转基因的表达显示出强烈的位置效应，变化范围为每个转基因拷贝 700 倍，即使整个 β-珠蛋白基因作为 lacZ 报告基因的一部分并入，这些位置效应也会发生。此外，DNase I 超敏位点出现在高表达的转基因 LCR 中，但不在低表达细胞系中出现，表明 LCR 本身是位置依赖性的。相比之下，选择转录活性整合位点的 MEL 细胞克隆给出了
The beta-globin locus control region (LCR) confers high levels of position-independent, copy number-dependent expression onto globin transgenes. Here >40 independent transgenic mouse lines and founders that carried the LCR in cis with the beta-globin gene promoter driving a lacZ reporter gene were studied, Expression of the lacZ transgene was assayed by measuring beta-galactosidase enzyme activity in fetal liver extracts, the levels of which correlated with the quantity of lacZ mRNA determined using RNase protection assays, Unexpectedly, expression of the lacZ transgene was found to show strong position effects, varying as much as 700-fold per transgene copy, These position effects occurred even if the whole beta-globin gene was incorporated as part of the lacZ reporter gene, Moreover, DNase I-hypersensitive sites appeared in the transgene LCR in high expressing but not in low expressing lines, suggesting that the LCR itself was position dependent, In contrast, MEL cell clones, in which transcriptionally active integration sites were selected for, gave