Functional analysis of regulatory regions upstream and in the first intron of the estrogen-responsive chicken very low density apolipoprotein II gene.
Functional analysis of regulatory regions upstream and in the first intron of the estrogen-responsive chicken very low density apolipoprotein II gene.
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DOI：
10.1016/s0021-9258(19)50548-8
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发表时间：
1992-04
期刊：
影响因子：
--
通讯作者：
E. A. Berkowitz;M. Evans
中科院分区：
文献类型：
--
作者：
E. A. Berkowitz;M. Evans
雌激素调节蛋鸡产蛋期间肝脏中卵黄蛋白基因的表达。虽然所有这五个基因，卵黄蛋白原I、II和III，极低密度载脂蛋白II(Apo VLDLII)和载脂蛋白B都对雌激素有反应，但个体对照叠加在它们在诱导动力学、反应幅度和发育表达方面的协调调节上。雌激素敏感的来航株M肝癌(LMH)细胞系为研究这些基因调控异同的分子基础提供了一个模型系统。在LMH细胞中，apoVLDLII基因受雌激素以适当的时间和剂量依赖的方式调节。ApoVLDLII基因的调控区已经通过瞬时转基因研究在LMH细胞中被确定。这四个序列都是在-26的TAATA基序和-171的近端雌激素反应元件之间结合蛋白的，在apoVLDLII基因的调控中是必不可少的。任何单个结合区的突变都会减少80%以上的表达，这表明整个区域的蛋白质之间存在协同作用。虽然这些序列将指导功能转录复合体的组装，但我们证明，将apoVLDLII基因的第一个内含子添加到启动子结构中，导致瞬时转染LMH细胞后雌激素依赖性表达增加4倍。缺失分析的结果表明，内含子的两个不同区域参与了这一调控。
Estrogen regulates the expression of the yolk protein genes in the chicken liver during periods of egg laying. While all five of these genes, vitellogenins I, II, and III, very low density apolipoprotein II (apo VLDLII), and apolipoprotein B, respond to estrogen, individual controls are superimposed on their coordinate regulation with respect to the kinetics of induction, magnitude of response, and developmental expression. The estrogen-responsive Leghorn strain M hepatoma (LMH) cell line provides a model system for studying the molecular basis of the similarities and differences in the regulation of these genes. The apoVLDLII gene is regulated by estrogen in LMH cells in an appropriate time- and dose-dependent manner. Regulatory regions of the apoVLDLII gene have been identified by transient transfection studies in LMH cells. All four of the sequences previously shown to bind protein between the TAATA motif at -26 and proximal estrogen response element at -171 are essential in regulation of the apoVLDLII gene. Mutation of any single binding region reduces expression by more than 80%, indicating cooperative interactions of proteins across the entire region. While these sequences will direct assembly of a functional transcription complex, we demonstrate that addition of the first intron of the apoVLDLII gene to the promoter construct results in a 4-fold increase in estrogen-dependent expression following transient transfection into LMH cells. Results of deletion analyses indicate that two distinct regions of the intron contribute to this regulation.