Transcriptional synergism between vitamin D-responsive elements in the rat 25-hydroxyvitamin D-3 24-hydroxylase (CYP24) promoter
Transcriptional synergism between vitamin D-responsive elements in the rat 25-hydroxyvitamin D-3 24-hydroxylase (CYP24) promoter
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DOI：
10.1074/jbc.271.47.29715
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发表时间：
1996-11-22
影响因子：
4.8
通讯作者：
May, BK
中科院分区：
文献类型：
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作者：
Kerry, DM;Dwivedi, PP;May, BK
1，25-（OH）（2）D-3通过维生素D受体依赖性过程诱导CYP 24基因的转录。通过在COS-1、JTC-12和ROS 17/2.8细胞中瞬时表达天然和突变启动子构建体，研究了位于大鼠CYP 24启动子反义链上的三种可能的维生素D反应元件（VDRES）的功能活性。在-249/-232（VDRE-3）处具有6个碱基对的半位点间距的推定VDRE不有助于天然启动子中的1，25-（OH）（2）D-3诱导的表达，尽管当该元件与异源胸苷激酶启动子融合时已经报道了活性，当用1，25-（OH）（2）D-3（10（-7）至10（-11）M）处理时，在COS-1细胞中具有3个碱基对的半位点间距的两个VDRE（分别为VDRE-1和VDRE-2）显示转录协同作用。在10（-10）至10（-12）M范围内，两种VDRE的贡献均具有浓度依赖性，VDRE-1对1，25-（OH）（2）D-3的敏感性最高。VDRE-1的反式激活作用总是大于VDRE-2，但在凝胶迁移率变动分析中，观察到每种VDRE与维生素D受体-类维生素A X受体复合物的结合相反。VDRE-1和VDRE-2之间观察到的协同作用可能对细胞对不同循环水平的1，25-（OH）（2）D-3的反应具有重要意义。
Transcription of the CYP24 gene is induced by 1,25-(OH)(2)D-3 through a vitamin D receptor-dependent process. The functional activities of three possible vitamin D response elements (VDREs), located on the antisense strand of the rat CYP24 promoter, were investigated by transient expression of native and mutant promoter constructs in COS-1, JTC-12, and ROS 17/2.8 cells. A putative VDRE with a half-site spacing of 6 base pairs at -249/-232 (VDRE-3) did not contribute to 1,25-(OH)(2)D-3 induced expression in the native promoter, although activity has been reported when the element was fused to the heterologous thymidine kinase promoter, Two VDREs with half-site spacings of 3 base pairs at -150/-136 and -258/-244 (VDRE-1 and VDRE-2, respectively), showed transcriptional synergism in COS-1 cells when treated with 1,25-(OH)(2)D-3 (10(-7) to 10(-11) M). The contribution of both VDREs was hormone-concentration dependent from 10(-10) to 10(-12) M, with VDRE-1 demonstrating greatest sensitivity to 1,25-(OH)(2)D-3. Transactivation by VDRE-1 was always greater than VDRE-2, but the converse was observed for the binding of vitamin D receptor-retinoid X receptor complex by each VDRE in gel mobility shift assays, The synergy observed between VDRE-1 and VDRE-2 may have important implications in cellular responses to different circulating levels of 1,25-(OH)(2)D-3.