Travali S, Lipson K E, Jaskulski D, Lauret E, Baserga R
Department of Pathology and Fels Research, Temple University Medical School, Philadelphia, Pennsylvania 19140.
Mol Cell Biol. 1988 Apr;8(4):1551-7. doi: 10.1128/mcb.8.4.1551-1557.1988.
To identify the regulatory elements of the human thymidine kinase (TK) gene, we have established stable cell lines carrying different chimeric constructs of the TK gene. Our results can be summarized as follows. (i) When the TK coding sequence is under the control of the calcyclin promoter (a promoter that is activated when G0 cells are stimulated by growth factors), TK mRNA levels are higher in G1-arrested cells than in proliferating cells; (ii) when the TK coding sequence is under the control of the promoter of heat shock protein HSP70, steady-state levels of TK mRNA are highest after heat shock, regardless of the position of the cells in the cell cycle; (iii) the bacterial CAT gene under the control of the human TK promoter is maximally expressed in the S phase; (iv) the TK cDNA driven by the simian virus 40 promoter is also maximally expressed in the S phase; and (v) TK enzyme activity is always at a maximum in the S phase, even when the levels of TK mRNA are highest in nonproliferating cells. We conclude that although the TK coding sequence may also play some role, the TK promoter has an important role in the cell cycle regulation of TK mRNA levels.
为了鉴定人类胸苷激酶（TK）基因的调控元件，我们建立了携带不同TK基因嵌合构建体的稳定细胞系。我们的结果可总结如下。（i）当TK编码序列受钙调蛋白启动子（一种在G0细胞受到生长因子刺激时被激活的启动子）控制时，G1期停滞细胞中的TK mRNA水平高于增殖细胞；（ii）当TK编码序列受热休克蛋白HSP70启动子控制时，无论细胞在细胞周期中的位置如何，热休克后TK mRNA的稳态水平最高；（iii）受人类TK启动子控制的细菌CAT基因在S期表达量最大；（iv）由猿猴病毒40启动子驱动的TK cDNA在S期也表达量最大；以及（v）即使在非增殖细胞中TK mRNA水平最高时，TK酶活性在S期也总是处于最大值。我们得出结论，尽管TK编码序列可能也起一定作用，但TK启动子在TK mRNA水平的细胞周期调控中具有重要作用。
