Bridges E G, Trentesaux C, Lahlil R, Spiga M G, Jeannesson P, Sommadossi J P
Department of Pharmacology and Toxicology, Center for AIDS Research and the Comprehensive Cancer Center, University of Alabama at Birmingham, USA.
Eur J Haematol. 1996 Jan-Feb;56(1-2):62-7. doi: 10.1111/j.1600-0609.1996.tb00296.x.
The present study examines genetic mechanism(s) possibly involved in the observed 3'-azido-3'-deoxythymidine (AZT)-induced inhibition of globin gene transcription by evaluating the direct phenotypic erythroid effects of AZT on erythroid-specific transcription factors which regulate globin gene promoters. In vitro binding of GATA-1 or NFE-2 to its consensus sequence was decreased in the presence of AZT reaching a maximum inhibition as early as 24 h after AZT treatment. Nuclear extracts from butyric acid-induced K562 cells treated with an IC50 concentration of AZT exhibited a decrease in GATA-1 and NFE-2 binding by approximately 30% and 35%. In contrast, 2',3'-dideoxycytidine which inhibits cell growth without affecting hemoglobin synthesis, had no effect on binding of GATA-1 and NFE-2 factors. Northern blot analysis revealed a 25% decrease by AZT in GATA-1 mRNA steady-state levels at 24 h and this inhibitory effect was maintained until 72 h after drug addition. A similar decrease in NFE-2 mRNA steady-state levels was observed at 72 h after AZT treatment. This study suggests that AZT inhibition of erythroid differentiation is subsequent to a decrease of nuclear factors gene expression which affect their DNA binding.
本研究通过评估齐多夫定（AZT）对调控珠蛋白基因启动子的红系特异性转录因子的直接表型红系效应，来研究可能参与观察到的AZT诱导的珠蛋白基因转录抑制的遗传机制。在AZT存在的情况下，GATA-1或NFE-2与其共有序列的体外结合减少，早在AZT处理后24小时就达到最大抑制。用AZT的IC50浓度处理丁酸诱导的K562细胞后，核提取物中GATA-1和NFE-2的结合减少了约30%和35%。相比之下，抑制细胞生长但不影响血红蛋白合成的2'，3'-双脱氧胞苷对GATA-1和NFE-2因子的结合没有影响。Northern印迹分析显示，AZT在24小时时使GATA-1 mRNA稳态水平降低了25%，并且这种抑制作用一直维持到添加药物后72小时。在AZT处理后72小时观察到NFE-2 mRNA稳态水平有类似的降低。这项研究表明，AZT对红系分化的抑制是在影响其DNA结合的核因子基因表达降低之后发生的。
