Alternariol acts as a topoisomerase poison, preferentially affecting the IIα isoform
Alternariol acts as a topoisomerase poison, preferentially affecting the IIα isoform
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DOI：
10.1002/mnfr.200700379
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发表时间：
2009-04-01
影响因子：
5.2
通讯作者：
Marko, Doris
中科院分区：
文献类型：
--
作者：
Fehr, Markus;Pahlke, Gudrun;Marko, Doris
Alternariol （AOH）是由alternnaria alternata形成的一种真菌毒素，据报道具有遗传毒性。然而，其潜在的作用机制尚不清楚。在这里，我们验证了与dna拓扑异构酶的相互作用在AOH的dna损伤特性中起作用的假设。首先，我们比较了AOH与其他真菌毒素如AOH单甲醚（AME）、丙烯烯和异丙烯烯的dna损伤特性。AOH和AME在微摩尔浓度下显著增加了人癌细胞（HT29, A431） DNA链断裂率，而altenuene和异altenuene在100 μ m范围内不影响DNA完整性。接下来，我们选择AOH作为最具DNA损伤性的Alternaria代谢物，进一步研究其与DNA拓扑异构酶的相互作用。在无细胞实验中，AOH能有效抑制DNA松弛，刺激拓扑异构酶I、II α和II β的DNA切割活性。在细胞培养中也可以检测到AOH对共价拓扑异构酶II- dna中间体的稳定作用，在这里，II α异构体被优先靶向。因此，AOH被认为是拓扑异构酶I和II的一种毒素，对II α亚型具有一定的选择性。由于拓扑异构酶中毒和DNA链断裂发生在同一浓度范围内，因此拓扑异构酶I和II的中毒可能至少对AOH的遗传毒性有贡献。
Alternariol (AOH), a mycotoxin formed by Alternaria alternata, has been reported to possess genotoxic properties. However, the underlying mechanism of action is unclear. Here, we tested the hypothesis that interactions with DNA-topoisomerases play a role in the DNA-damaging properties of AOH. First we compared DNA-damaging properties of AOH with other Alternaria mycotoxins such as AOH monomethyl ether (AME), altenuene and isoaltenuene. AOH and AME significantly increased the rate of DNA strand breaks in human carcinoma cells (HT29, A431) at micromolar concentrations, whereas altenuene and isoaltenuene did not affect DNA integrity up to 100 mu M. Next, we selected AOH as the most DNA-damaging Alternaria metabolite for further Studies of interactions with DNA topoisomerases. In cell-free assays, AOH potently inhibited DNA relaxation and stimulated DNA cleavage activities of topoisomerase I, II alpha and II beta. Stabilisation of covalent topoisomerase II-DNA intermediates by AOH was-also detectable in cell Culture, and here, the II alpha isoform was preferentially targeted. AOH is thus characterised as a poison of topoisomerase I and II with a certain selectivity for the II alpha isoform. Since topoisomerase poisoning and DNA strand breakage occurred within the same concentration range, poisoning of topoisomerase I and II might at least contribute to the genotoxic properties of AOH.