Transcriptional activation of the MDR1 gene by UV irradiation - Role of NF-Y and Sp1
Transcriptional activation of the MDR1 gene by UV irradiation - Role of NF-Y and Sp1
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DOI：
10.1074/jbc.275.4.2979
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发表时间：
2000-01-28
影响因子：
4.8
通讯作者：
Scotto, KW
中科院分区：
文献类型：
--
作者：
Hu, Z;Jin, SK;Scotto, KW
MDR1启动子受各种内部和外部刺激的控制。我们先前已经证明，CCAAT盒结合蛋白NF-Y通过共激活因子P/CAF的募集，介导组蛋白去乙酰化酶抑制剂曲古菌素A和丁酸钠对MDR1的激活。我们现在将我们的研究扩展到通过基因毒性应激激活mdr1。我们发现，紫外线照射对MDR1启动子的激活也取决于CCAAT盒(-82到-73)以及近端的GC元件(-56到-42)。对人KB-3-1细胞核提取液的凝胶位移和超位移分析表明，NF-Y是与CCAAT盒相互作用的转录因子，而SPL是与GC元件结合的主要因子。取消这两种因子的结合的突变减少或取消了紫外线照射的激活；此外，共表达显性负核因子-Y蛋白(NE-YA29)减少了紫外线激活的转录。有趣的是，YB-1，一个也识别CCAAT基序的转录因子，被报道介导紫外线诱导MDR1启动子，尽管它确实与单链寡核苷酸相互作用，但它不能与核提取液中的双链MDR1 CCAAT盒寡核苷酸相互作用。此外，通过W-射线照射取消MDR1激活的突变对YB-1的结合没有影响，与YB-1表达载体共转染对紫外线诱导的转录有抑制作用。综上所述，这些结果表明，NF-Y和SPL在基因毒性应激下MDR1基因的转录激活中都起到了作用，并且表明YB-1如果参与的话，不足以介导这种激活。
The MDR1 promoter is subject to control by various internal and external stimuli. We have previously shown that the CCAAT box-binding protein, NF-Y, mediates MDR1 activation by the histone deacetylase inhibitors, trichostatin A and sodium butyrate, through the recruitment of the co-activator, P/CAF. We have now extended our investigation to the activation of MDR1 by genotoxic stress. We show that activation of the MDR1 promoter by UV irradiation is also dependent on the CCAAT box (-82 to -73) as well as on a proximal GC element (-56 to -42). Gel shift and supershift analyses with nuclear extracts prepared from human KB-3-1 cells identified NF-Y as the transcription factor interacting with the CCAAT box, while Spl was the predominant factor binding to the GC element. Mutations that abrogated binding of either of these factors reduced or abolished activation by ultraviolet irradiation; moreover, co-expression of a dominant-negative NF-Y protein (NE-YA29) reduced UV-activated transcription. Interestingly, YB-1, a transcription factor that also recognizes the CCAAT motif and had been reported to mediate induction of the MDR1 promoter by ultraviolet light, was incapable of interacting with the double-stranded MDR1 CCAAT box oligonucleotide in nuclear extracts, although it did interact with a single-stranded oligonucleotide. Furthermore, a mutation that abolished activation of MDR1 by W-irradiation had no effect on YB-1 binding and co-transfection of a YB-1 expression plasmid had a repressive effect on UV-inducible transcription. Taken together, these results indicate a role for both NF-Y and Spl in the transcriptional activation of the MDR1 gene by genotoxic stress, and indicate that YB-1, if involved, is not sufficient to mediate this activation.