S phase-specific transcription of the mouse ribonucleotide reductase R2 gene requires both a proximal repressive E2F-binding site and an upstream promoter activating region
S phase-specific transcription of the mouse ribonucleotide reductase R2 gene requires both a proximal repressive E2F-binding site and an upstream promoter activating region
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DOI：
10.1074/jbc.m312482200
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发表时间：
2004-03-12
影响因子：
4.8
通讯作者：
Thelander, L
中科院分区：
文献类型：
--
作者：
Chabes, AL;Björklund, S;Thelander, L
核糖核苷酸还原酶对于提供DNA合成和修复所需的四种脱氧核糖核苷酸的平衡池至关重要。活性酶由两个不相同的亚基组成，称为蛋白质R1和R2。核糖核苷酸还原酶活性有多个水平的调节，在哺乳动物细胞中，在未受干扰的细胞周期的S和G（2）期最高。文献中的先前报道已经表明哺乳动物R2基因的S期特异性转录受转录阻断的调节，依赖于转录因子E2 F1，或者简单地受与启动子CCAAT盒加上TATA盒结合的蛋白质的调节。在这里，我们证明了小鼠R2基因的S期特异性转录依赖于上游启动子激活区（位于转录起始位点的核苷酸（nt）-672至-527）和一个近端启动子抑制元件（位于nt - 112至-107），结合E2 F4。与E2 F位点的结合通过核因子Y与相邻CCAAT元件（nt - 79至-75）的结合来调节。上游激活区对整个R2启动子活性至关重要。E2 F结合位点的突变导致G（1）中启动子的过早激活，并增加总体启动子活性，但仅当上游激活区存在且完整时。因此，E2 F依赖性抑制是细胞周期特异性R2转录所必需的。
Ribonucleotide reductase is essential for supplying a balanced pool of the four deoxyribonucleotides required for DNA synthesis and repair. The active enzyme consists of two non-identical subunits called proteins R1 and R2. There are multiple levels of regulation of ribonucleotide reductase activity, which is highest during the S and G(2) phases of an unperturbed cell cycle in mammalian cells. Previous reports in the literature have indicated that the S phase-specific transcription of the mammalian R2 gene is regulated by a transcriptional block, is dependent on the transcription factor E2F1, or is simply regulated by proteins that bind to promoter CCAAT boxes plus the TATA box. Here, we demonstrate that the S phase-specific transcription of the mouse R2 gene is dependent on an upstream promoter activating region (located at nucleotides (nt) - 672 to - 527 from the transcription start site) and one proximal promoter repressive element ( located at nt - 112 to - 107) that binds E2F4. Binding to the E2F site is modulated by binding of nuclear factor-Y to an adjacent CCAAT element ( nt - 79 to - 75). The upstream activating region is crucial for overall R2 promoter activity. Mutation of the E2F-binding site leads to premature promoter activation in G(1) and increases overall promoter activity but only when the upstream activating region is present and intact. Therefore, E2F-dependent repression is essential for cell cycle-specific R2 transcription.