Specificity of transcriptional regulation by the zinc finger transcription factors Sp1, Sp3, and Egr-1
Specificity of transcriptional regulation by the zinc finger transcription factors Sp1, Sp3, and Egr-1
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DOI：
10.1002/jcb.20305
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发表时间：
2005-01-01
影响因子：
4
通讯作者：
Thiel, G
中科院分区：
文献类型：
--
作者：
Al-Sarraj, A;Day, RM;Thiel, G
转录因子 Sp1、Sp3 和 Egr-1 通过其锌指 DNA 结合域与其靶基因调控区域中富含 GC 的序列结合。 Sp1、Sp3 和 Egr-1 的 DNA 结合位点的相似性引发了这样的假设：它们竞争相同的 DNA 结合位点。我们使用显性失活突变体分别阻断 Sp1、Sp3 或 Egr-1 的 DNA 结合位点，研究了 Sp1、Sp3 和 Egr-1 转录调控的特异性。结果表明，Sp1 调节的报告基因（包含源自醛缩酶 C 和 p21（WAF1/Cip1）基因的 Sp1 位点或 HIV-1 的长末端重复序列）的组成型转录受到 Sp1 和 Sp3 显性失活突变体的损害，但不受显性失活 Egr-1 的影响。 Egr-1 介导的转录是通过转染编码野生型或突变型 Egr-1 的表达载体或通过诱导型 B-Raf-雌激素受体融合蛋白刺激细胞外信号调节蛋白激酶途径来诱导的。在所有情况下，Egr-1 调节的报告基因（包含源自 Egr-1 或突触蛋白 I 基因的 Egr-1 结合位点）的转录均会受到显性失活 Egr-1 的损害，但不会受到显性失活 Sp1 或 Sp3 突变体的影响。这些结果表明，存在真正的 Sp1/Sp3 或 Egr-1 控制基因，显示 Sp1/Sp3 和 Egr-1 通过相同 DNA 结合位点没有交叉调节。这并不排除复合 Sp1/Sp3/Egr-1 结合位点的存在，其中发生对共同 DNA 结合位点的竞争。 (C) 2004 Wiley-Liss, Inc.
The transcription factors Sp1, Sp3, and Egr-1 bind with their zinc finger DNA-binding domains to GC-rich sequences in the regulatory regions of their target genes. The similarity of the DNA-binding sites of Sp1, Sp3, and Egr-1 has triggered the hypothesis that they compete for the same DNA-binding site. We have investigated the specificity of transcriptional regulation by Sp1, Sp3, and Egr-1 using dominant-negative mutants that block the DNA-binding site of Sp1, Sp3, or Egr-1 respectively. The results show that constitutive transcription of Sp1 regulated reporter genes, containing Sp1 sites derived from the aldolase C and p21(WAF1/Cip1) genes, or the long terminal repeat of HIV-1, was impaired by dominant-negative mutants of Sp1 and Sp3, but not by a dominant-negative Egr-1. Transcription mediated by Egr-1 was induced by transfection of expression vectors encoding wild-type or mutated Egr-1 or by stimulation of the extracellular signal-regulated protein kinase pathway via an inducible B-Raf-estrogen receptor fusion protein. In all cases transcription of Egr-1-regulated reporter genes, containing Egr-1 binding sites derived from the Egr-1 or the synapsin I gene was impaired by a dominant-negative Egr-1, but not by dominant-negative Sp1 or Sp3 mutants. These results show that there are genuine Sp1/Sp3 or Egr-1 controlled genes showing no cross-regulation of Sp1/Sp3 and Egr-1 through the same DNA-binding site. This does not exclude the existence of composite Sp1/Sp3/Egr-1 binding sites, where competition for a common DNA-binding site occurs. (C) 2004 Wiley-Liss, Inc.