Mechanisms behind Topoisomerase II SUMOylation in chromosome segregation.
Mechanisms behind Topoisomerase II SUMOylation in chromosome segregation.
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染色体分离中拓扑异构酶 II SUMO 化背后的机制。
DOI：
10.1080/15384101.2016.1216928
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Azuma,Yoshiaki
中科院分区：
文献类型：
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作者：
Yoshida,MakotoM;Azuma,Yoshiaki
在有丝分裂过程中被发现被 SUMO 化的主要底物之一是 DNA 拓扑异构酶 IIa (TOP2A)，这是一种调节基因组 DNA 拓扑结构的酶。有趣的是，虽然 TOP2A 结合在整个染色体上，但大多数 SUMO 化的 TOP2A 可能在早期有丝分裂发生 SUMO 化时聚集在有丝分裂着丝粒处。 1 对芽殖酵母中 TOP2 SUMO 化位点的遗传学研究揭示了 TOP2A SUMO 化在有丝分裂过程中的重要性。 TOP2 CTD被发现在多个赖氨酸处被SUMO化，并且阻止CTD处SUMO化的突变导致芽殖酵母中着丝粒DNA的内聚力缺陷，并导致感测微管-着丝粒附着位点张力的纺锤体检查点的缺陷。 2, 3 这表明 TOP2A CTD SUMO 化可能调节 Aurora B 激酶，它是纺锤体检查点和中期到后期进展的关键调节因子。在有丝分裂过程中发现的另一个被 SUMO 化的位点位于非洲爪蟾 TOP2A 赖氨酸 660 (K660) 上，该位点位于该酶的催化核心内。 1 K660 的 SUMO 化极大地抑制 TOP2A 的去连接活性。这种抑制的功能可能是通过防止姐妹染色单体缠结的着丝粒 DNA 被分解来维持姐妹染色单体的凝聚力。有趣的是，TOP2A SUMO 化的生化分析已确定 CTD 赖氨酸位点 SUMO 化不会影响 TOP2A 的去连接活性。 4 因此，通过 TOP2A CTD SUMOylation 调节纺锤体检查点的机制仍不清楚。直到最近，TOP2A CTD SUMOylation 调节 Aurora B 的途径才被发现。我们实验室最近的工作确定非典型组蛋白 H3 激酶 Haspin 作为 SUMO 结合蛋白与 TOP2A 相互作用。 5 Haspin 在苏氨酸 3 (H3T3) 处磷酸化着丝粒组蛋白 H3，为染色体过客复合体 (CPC)（包括有丝分裂着丝粒处的 Aurora B）提供结合位点。我们的结果确定，TOP2A CTD SUMOylation 可以通过将 Haspin 募集到有丝分裂染色体上来调节 Haspin（其着丝粒定位机制以前尚不清楚），并且在爪蟾卵提取物模型系统中，SUMOylation 的抑制使 Haspin 错误定位离开着丝粒。此外，同时在芽殖酵母中进行的一项研究表明，缺乏 CTD 的 TOP2 突变株和不可 SUMO 化的 TOP2 CTD 突变株均无法将 Aurora B 在着丝粒上正确定位，这表明 TOP2 CTD 通过 SUMO 接合在酵母和脊椎动物之间具有保守作用。 6 思考 TOP2A 上的 SUMO 修饰如何在有丝分裂的同一阶段调节不同的功能是很有趣的。催化核心内 K660 的 SUMO 化抑制了解析缠结的着丝粒 DNA 所需的 TOP2A 串联活性，因此维持了姐妹染色单体的内聚力。 4 另一方面，CTD 的 SUMO 化通过 Haspin-H3T3p 途径将包括 Aurora B 在内的 CPC 招募到着丝粒，以实现成功的中期到后期的转变。 5, 6 乍一看，TOP2A 上的 SUMO 修饰的这两种功能以相反的方式发挥作用：一种防止姐妹染色单体分离，另一种促进向后期染色体分离的转变。早期有丝分裂期间发生的 TOP2A SUMO 修饰的这两个功能如何协调以导致染色体正确分离到子细胞中？当他们行动时……
One of the major substrates discovered to be SUMOylated during mitosis is DNA topoisomerase IIa (TOP2A), an enzyme that regulates the topology of genomic DNA. Interestingly, while TOP2A binds throughout the chromosome the majority of the SUMOylated TOP2A is likely clustered at the mitotic centromeres during early mitosis when SUMOylation occurs. 1 Genetic studies in budding yeast on the SUMOylation sites of TOP2 have revealed the importance of TOP2A SUMOylation during mitosis. TOP2 CTD has been found to be SUMOylated at multiple lysines, and mutations to prevent SUMOylation at the CTD led to defects in the cohesion of the centromeric DNA in budding yeast, and led to a defect in the spindle checkpoint that senses tension at the microtubules-kinetochore attachment sites. 2, 3 This suggests that TOP2A CTD SUMOylation may regulate Aurora B kinase, the key regulator of the spindle checkpoint and metaphase-to-anaphase progression. An additional site discovered to be SUMOylated during mitosis is on Xenopus laevis TOP2A lysine 660 (K660) that is within the catalytic core of the enzyme. 1 SUMOylation of K660 greatly inhibits TOP2A decatenation activity. The function of this inhibition is likely to maintain the cohesion of the sister chromatids by keeping the entangled centromeric DNA of the sister chromatids from being resolved. Interestingly, biochemical analysis of TOP2A SUMOylation has determined that SUMOylating the CTD lysine sites does not affect TOP2A decatenation activity. 4 Therefore, the mechanism behind the regulation of the spindle checkpoint through TOP2A CTD SUMOylation has remained unknown. Not until recently was the pathway of TOP2A CTD SUMOylation in the regulation of Aurora B discovered. Recent work from our laboratory determined that the atypical histone H3 kinase Haspin interacts with TOP2A as a SUMO-binding protein. 5 Haspin phosphorylates centromeric histone H3 at threonine 3 (H3T3), which provides a binding site for the chromosomal passenger complex (CPC) including Aurora B at the mitotic centromeres. Our results determined that TOP2A CTD SUMOylation can regulate Haspin, whose centromeric localization mechanism was previously unclear, by recruiting it onto the mitotic chromosomes, and that inhibition of SUMOylation mis-localizes Haspin off of the centromeres in the Xenopus egg extract model system. Additionally, a concurrent study in budding yeast showed that both TOP2 mutant strain lacking the CTD and non-SUMOylatable TOP2 CTD mutant strain yielded failure in the proper localization of Aurora B at the centromeres, which suggests a conserved role of the TOP2 CTD between yeast and vertebrates through SUMO conjugation. 6 It is interesting to think about how the SUMO modification on TOP2A can regulate different functions during the same stage in mitosis. The SUMOylation of the K660 within the catalytic core inhibits TOP2A decatenation activity necessary to resolve the entangled centromeric DNA, and therefore, maintains the cohesion of the sister chromatids. 4 On the other hand, SUMOylation of the CTD recruits CPC including Aurora B to the centromere via the Haspin-H3T3p pathway for a successful metaphase-to-anaphase transition. 5, 6 At first glance, these 2 functions of SUMO modification on TOP2A act in opposite manners: one that prevents the sister chromatids from being separated, and one that promotes the transition to anaphase for chromosome segregation. How can these 2 functions of TOP2A SUMO modifications that occur during early mitosis coordinate to lead to the proper segregation of chromosomes into the daughter cells? While they act …