Function of the upstream hypersensitive sites of the chicken beta-globin gene cluster in mice.
Function of the upstream hypersensitive sites of the chicken beta-globin gene cluster in mice.
复制标题
小鼠鸡β-珠蛋白基因簇上游过敏位点的功能。
DOI：
10.1093/nar/23.10.1790
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发表时间：
1995
影响因子：
14.9
通讯作者：
H. Westphal
中科院分区：
文献类型：
--
作者：
M. Reitman;E. Lee;H. Westphal
我们先前已经证明，鸡β A-珠蛋白基因及其3'增强子在转基因小鼠中以拷贝数依赖性方式表达。表达水平低，但增加约6倍后，包括11 kb的上游DNA含有4个DNase I超敏感位点。为了研究单个上游超敏位点对转基因表达的影响，我们生产了小鼠品系，其中单个上游位点与β A基因和增强子相连。在成年动物的血液中测量RNA水平。对于这四种构建体中的每一种，每个DNA拷贝的转基因RNA水平在> 20倍的范围内变化。这些数据表明，添加一个超敏位点的β A-珠蛋白/增强子区域废除其位置独立的表达。携带上游位点的株系中每拷贝的平均β A-珠蛋白表达量与没有上游位点的株系中的每拷贝的平均β A-珠蛋白表达量相当。因此，没有单一的上游超敏位点解释在含有完整上游区域的小鼠中观察到的较高水平的β A-珠蛋白表达。我们之前已经表明，鸡β-珠蛋白簇的控制分布在至少两个区域之间，即β A/β B增强子和上游区域。我们目前的研究结果表明，上游DNA介导的控制本身是分布式的，而不是由于一个单一的过敏网站。
We have shown previously that the chicken beta A-globin gene, with its 3' enhancer, is expressed in a copy number-dependent manner in transgenic mice. The expression level was low but increased approximately 6-fold upon inclusion of 11 kb of upstream DNA containing four DNase I hypersensitive sites. To study the effect of the individual upstream hypersensitive sites on transgene expression, we produced lines of mice in which the individual upstream sites were linked to the beta A gene and enhancer. RNA levels were measured in blood from adult animals. With each of these four constructs, the level of transgene RNA per DNA copy varied over a > 20-fold range. These data suggest that addition of a hypersensitive site to the beta A-globin/enhancer region abrogates its position independent expression. The average beta A-globin expression per copy in the lines carrying an upstream site was comparable with that in lines without an upstream site. Thus, no single upstream hypersensitive site accounts for the higher level of beta A-globin expression seen in mice containing the complete upstream region. We had shown previously that control of the chicken beta-globin cluster is distributed between at least two regions, the beta A/epsilon enhancer and the upstream region. Our current results suggest that the control mediated by the upstream DNA is itself distributed and is not due to a single hypersensitive site.