Functional compatibility between isoform α and β of type II DNA topoisomerase
Functional compatibility between isoform α and β of type II DNA topoisomerase
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DOI：
10.1242/jcs.00977
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发表时间：
2004-03
影响因子：
4
通讯作者：
A. Sakaguchi;A. Kikuchi
中科院分区：
文献类型：
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作者：
A. Sakaguchi;A. Kikuchi
DNA拓扑异构酶II(Topo II)在控制DNA和整个染色体的构象方面起着至关重要的作用。这种活性对DNA复制、转录、染色体凝聚和分离等几个细胞事件是必不可少的。在哺乳动物中，有两个基因编码TOPO II的异构体，称为α和β。它们在一级结构上相似，在体外具有几乎相同的催化性能。我们用针对Topo IIα或IIβ的小干扰RNA(SiRNA)导入HeLa细胞，并成功地下调了相应蛋白的表达。在TOPO IIα敲除细胞中，染色体在中期密集排列。虽然观察到了一些落后的染色体，但在后期仍然是分离的，尽管没有Topo IIα。当Topo IIα和Topo IIγ都被去除时，染色体的分离被严重阻止，表明Topo IIγ可以部分取代Topo IIα。双敲除实验还表明，Topo II是缩短染色体轴所必需的。
DNA topoisomerase II (topo II) plays a crucial role in controlling the conformation of both DNA and whole chromosomes. This activity is essential for several cellular events such as DNA replication, transcription, chromosome condensation and segregation. In mammals, two genes code for isoforms of topo II, termed α and β. They are similar in primary structure and have almost identical catalytic properties in vitro. We transfected HeLa cells with small interfering RNAs (siRNAs) targeted against either topo IIα or IIβ, and succeeded in knocking down the expression of the corresponding protein. Chromosomes were condensed and aligned at metaphase in topo IIα-knockdown cells. Although some lagging chromosomes were observed, they were still segregated at anaphase despite the absence of topo IIα. When both topo IIα and topo IIγ were removed, the segregation of chromosomes was severely arrested, suggesting that topo IIγ could partially substitute for topo IIα. Double-knockdown experiments also revealed that topo II was required for shortening of the chromosome axis.