Duan Zhi-Jun, Fang Xiangdong, Rohde Alex, Han Hemei, Stamatoyannopoulos George, Li Qiliang
Division of Medical Genetics, Department of Medicine, University of Washington Medical School, Box 357720, Seattle, WA 98195, USA.
Proc Natl Acad Sci U S A. 2002 Apr 16;99(8):5509-14. doi: 10.1073/pnas.072084499.
It is unclear whether the core promoter is involved in developmental regulation. To address this question, we mutated the TATA box of the human gamma-globin gene, produced transgenic mice, and examined the effect of the mutation during the course of mouse development. In our test system, the gamma-globin gene is expressed at similar levels in the embryonic and adult erythroid cells. The TATA box mutation dramatically reduced expression of the gamma-globin gene in the adult but not in embryonic erythroid cells. In addition, the disruption of the gamma TATA box significantly reduced the recruitment of TATA box-binding protein (TBP) in the adult cells, but not in embryonic cells, suggesting that the recruitment of TBP to the gamma gene promoter is developmentally specific. Similarly, the recruitment of transcription factor II B and RNA polymerase II to the gamma promoter was affected in the adult but not in embryonic cells. The distinct effects of the TATA mutation in the embryonic and adult developmental stages suggest that the basal transcription apparatus can be recruited to a core promoter in a developmental stage-dependent manner. The TATA mutation resulted in a shift of transcription initiation site 6 bp or longer upstream to the cap site both in the embryonic and adult erythrocytes. We conclude that the TATA box determines the initiation site but not the efficiency of transcription of the gamma-globin gene.
核心启动子是否参与发育调控尚不清楚。为了解决这个问题，我们对人类γ-珠蛋白基因的TATA盒进行了突变，制备了转基因小鼠，并在小鼠发育过程中检测了该突变的影响。在我们的测试系统中，γ-珠蛋白基因在胚胎期和成年期的红系细胞中表达水平相似。TATA盒突变显著降低了γ-珠蛋白基因在成年红系细胞中的表达，但在胚胎红系细胞中没有降低。此外，γ TATA盒的破坏显著降低了成年细胞中TATA盒结合蛋白（TBP）的募集，但在胚胎细胞中没有降低，这表明TBP募集到γ基因启动子具有发育特异性。同样，转录因子II B和RNA聚合酶II募集到γ启动子在成年细胞中受到影响，但在胚胎细胞中没有受到影响。TATA突变在胚胎期和成年期发育阶段的不同影响表明，基础转录装置可以以发育阶段依赖的方式募集到核心启动子上。TATA突变导致胚胎期和成年期红细胞中转录起始位点均向帽位点上游移动6个碱基对或更长。我们得出结论，TATA盒决定了γ-珠蛋白基因的转录起始位点，但不决定转录效率。
