Heiland S, Knippers R, Kunze N
Division of Biology, University of Konstanz, Germany.
Eur J Biochem. 1993 Nov 1;217(3):813-22. doi: 10.1111/j.1432-1033.1993.tb18309.x.
We examined the promoter of the human type-I-DNA topoisomerase gene (hTOP1) for regions protected against DNase I digestion by nuclear proteins from HeLa or from adenovirus-transformed 293 cells. We identified ten protected DNA sequences within 580 bp of DNA upstream of the transcriptional-start sites and one additional site, which is located between the two clusters of transcriptional-start sites. Several of these protein-binding sites have significant similarities to recognition sequences of known transcription factors including factors Sp1, octamer transcription factor, cAMP-responsive-element-binding protein (CREB/ATF), NF-kappa B and members of the Myc-related family of basic/helix-loop-helix/leucine-zipper proteins. Other protein-binding sites show less or no similarities to known consensus sequences. We investigated the physiological significance of these protein-binding sites using a set of deletion and nucleotide-exchange mutants. We conclude that the expression of the hTOP1 gene is regulated by a complex network of negatively and positively acting transcription factors.
我们检测了人类I型DNA拓扑异构酶基因（hTOP1）的启动子，寻找来自HeLa细胞或腺病毒转化的293细胞的核蛋白所保护的免受DNase I消化的区域。我们在转录起始位点上游580 bp的DNA范围内鉴定出10个受保护的DNA序列，以及另一个位于两个转录起始位点簇之间的位点。这些蛋白质结合位点中有几个与已知转录因子的识别序列具有显著相似性，这些转录因子包括Sp1因子、八聚体转录因子、cAMP反应元件结合蛋白（CREB/ATF）、NF-κB以及Myc相关的碱性/螺旋-环-螺旋/亮氨酸拉链蛋白家族成员。其他蛋白质结合位点与已知的共有序列相似度较低或没有相似性。我们使用一组缺失和核苷酸交换突变体研究了这些蛋白质结合位点的生理意义。我们得出结论，hTOP1基因的表达受正负作用转录因子组成的复杂网络调控。
