A composite regulatory element in the first intron of the estrogen-responsive very low density apolipoprotein II gene.
A composite regulatory element in the first intron of the estrogen-responsive very low density apolipoprotein II gene.
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雌激素反应性极低密度载脂蛋白 II 基因第一个内含子中的复合调控元件。
DOI：
10.1089/dna.1998.17.689
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
Evans,MI
中科院分区：
文献类型：
--
作者：
Shuler,FD;Chu,WW;Wang,S;Evans,MI
在鸡下蛋期间，当循环雌激素水平增加时，肝脏特异性雌激素依赖性极低密度载脂蛋白II （apoVLDLII）基因表达。这种表达主要发生在转录水平上，由位于启动子中的两种雌激素反应元件驱动。在瞬时转染实验中，当第一个内含子被添加到启动子结构中时，表达量增加了4倍，表明75%的调控来自内含子a。使用In vitroDNase I足迹，在第一个内含子中发现了6个蛋白质结合位点。通过突变和瞬时转染来评估这些结合位点的功能意义。其中两个蛋白质结合区显示增加转录。在+66至+86或+112至+129位点引入的位点特异性突变破坏了反式因子结合，并分别降低了45%和34%的雌激素依赖性表达。含有这两个突变的质粒导致43%的表达减少，表明这些区域的贡献不是相加的。在电泳迁移率转移实验中，与已知序列的竞争表明，+66到+86位点结合了鸡核受体转录因子家族的一个成员。
During periods of egg laying in the chicken, when circulating levels of estrogen are increased, the liver-specific estrogen-dependent very low density apolipoprotein II (apoVLDLII) gene is expressed. This expression takes place primarily at the level of transcription, driven by two estrogen response elements that reside in the promoter. In transient transfection assays, expression is increased fourfold when the first intron is added to the promoter construct, indicating that 75% of the regulation comes from intron A. Usingin vitroDNase I footprinting, six protein-binding sites were revealed throughout the first intron. The functional significance of these binding sites was evaluated by mutation and transient transfection. Two of the protein-binding regions were shown to increase transcription. Site-specific mutations introduced at either the +66 to +86 or +112 to +129 sites disruptedtrans-factor binding and reduced the estrogen-dependent expression by 45% and 34%, respectively. A plasmid containing both mutations resulted in a 43% decrease in expression, indicating that the contributions of these regions are not additive. Competition with known sequences in electrophoretic mobility shift assays suggested that the +66 to +86 site binds a chicken member of the nuclear receptor transcription factor family.