TDP1 overexpression in human cells counteracts DNA damage mediated by topoisomerases I and II
TDP1 overexpression in human cells counteracts DNA damage mediated by topoisomerases I and II
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DOI：
10.1074/jbc.m405042200
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发表时间：
2004-12-31
影响因子：
4.8
通讯作者：
Marko, D
中科院分区：
文献类型：
--
作者：
Barthelmes, HU;Habermeyer, M;Marko, D
酪氨酰DNA磷酸二酯酶1（TDP 1）是一种修复酶，可以去除加合物，如。G.拓扑异构酶I的3 '-磷酸DNA断裂。当以生物荧光嵌合体的形式在人类细胞中表达时，TDP 1比拓扑异构酶I表现出更移动的，在核仁中积累较少，并且在有丝分裂早期不与染色体结合。暴露于喜树碱后，两种蛋白质均从核仁中清除，并在核质中移动的较少。然而，与TDP 1，这发生得慢得多，反映了最有可能的核仁结构的重新分布后，抑制rDNA转录。因此，TDP 1与拓扑异构酶I的稳定结合似乎不太可能，而其整合到随后组装的修复复合物中以稳定DNA拓扑异构酶I中间体得到支持。表达GFP标记的TDP 1超过内源性TDP 1 100倍的细胞表现出拓扑异构酶I毒物喜树碱诱导的DNA损伤显着减少，并且可以被该药物选择。令人惊讶的是，由拓扑异构酶II毒物VP-16诱导的DNA损伤也减少到类似的程度，而不依赖于拓扑异构酶I或II的DNA损伤不受影响。相似水平的失活突变体GFP-TDP 1（H263 A）的过表达没有减少喜树碱或VP-16对DNA的损伤。这些观察结果证实了拓扑异构酶I介导的DNA损伤的修复需要活性TDP 1。我们的数据还表明，TDP 1在拓扑异构酶II介导的DNA损伤修复中的作用，这是不太清楚的。由于TDP 1的过表达不损害细胞增殖，因此它可能是癌症治疗中的多效性耐药机制。
Tyrosyl DNA phosphodiesterase 1 (TDP1) is a repair enzyme that removes adducts, e. g. of topoisomerase I from the 3'-phosphate of DNA breaks. When expressed in human cells as biofluorescent chimera, TDP1 appeared more mobile than topoisomerase I, less accumulated in nucleoli, and not chromosome-bound at early mitosis. Upon exposure to camptothecin both proteins were cleared from nucleoli and rendered less mobile in the nucleoplasm. However, with TDP1 this happened much more slowly reflecting most likely the redistribution of nucleolar structures upon inhibition of rDNA transcription. Thus, a steady association of TDP1 with topoisomerase I seems unlikely, whereas its integration into repair complexes assembled subsequently to the stabilization of DNA.topoisomerase I intermediates is supported. Cells expressing GFP-tagged TDP1 > 100-fold in excess of endogenous TDP1 exhibited a significant reduction of DNA damage induced by the topoisomerase I poison camptothecin and could be selected by that drug. Surprisingly, DNA damage induced by the topoisomerase II poison VP-16 was also diminished to a similar extent, whereas DNA damage independent of topoisomerase I or II was not affected. Overexpression of the inactive mutant GFP-TDP1(H263A) at similar levels did not reduce DNA damage by camptothecin or VP-16. These observations confirm a requirement of active TDP1 for the repair of topoisomerase I-mediated DNA damage. Our data also suggest a role of TDP1 in the repair of DNA damage mediated by topoisomerase II, which is less clear. Since overexpression of TDP1 did not compromise cell proliferation, it could be a pleiotropic resistance mechanism in cancer therapy.