Over the last several years enormous progress has been made in identifying the molecular machines, including condensins and topoisomerases that fold mitotic chromosomes. The discovery that condensins generate chromatin loops through loop extrusion has revolutionized, and energized, the field of chromosome folding. To understand how these machines fold chromosomes with the appropriate dimensions, while disentangling sister chromatids, it needs to be determined how they are regulated and deployed. Here, we outline the current understanding of how these machines and factors are regulated through cell cycle dependent expression, chromatin localization, activation and inactivation through post-translational modifications, and through associations with each other, with other factors and with the chromatin template itself. There are still many open questions about how condensins and topoisomerases are regulated but given the pace of progress in the chromosome folding field, it seems likely that many of these will be answered in the years ahead.

中文翻译：

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有丝分裂染色体折叠机的调节

在过去的几年中，在鉴定分子机器方面取得了巨大进展，包括折叠有丝分裂染色体的凝集素和拓扑异构酶。凝缩蛋白通过环挤压产生染色质环的发现彻底改变了染色体折叠领域，并为之注入了活力。要了解这些机器如何折叠具有适当尺寸的染色体，同时解开姐妹染色单体，需要确定它们是如何被调节和部署的。在这里，我们概述了目前对这些机器和因子如何通过细胞周期依赖性表达、染色质定位、激活和失活（通过翻译后修饰）以及通过相互关联、与其他因素和染色质模板本身的关联进行调节的理解。