Mitotic chromosome condensation resets chromatin to maintain post-anaphase transcriptional homeostasis (ATAC-Seq)

Mitotic entry correlates with remodeling of histone modifications, chromatin condensation, exclusion of transcription factors from the DNA and broad downregulation of transcription. However, whether mitotic condensation also influences interphase transcription is a question that has not been addressed yet. In this study, we reveal that loss of mitotic chromatin condensation results in a dramatic and spontaneous recruitment of the transcription machinery and unscheduled initiation of gene expression. This includes activation of inducible transcriptional programs, which occurs even in absence of relevant stimuli, such as the GAL system. Strikingly, such an erratic gene expression goes on after exit from mitosis. Thus, we reveal a novel function of mitotic chromosome condensation, i.e. resetting the transcriptome to prevent gene expression from drifting and maintain transcriptional homeostasis during interphase.细胞进入有丝分裂期与组蛋白修饰（histone modifications）重塑、染色质凝聚（chromatin condensation）、转录因子从DNA上解离以及转录的广泛下调密切相关。然而，有丝分裂凝聚是否也会影响间期转录，这一问题迄今尚未得到解答。本研究发现，有丝分裂染色质凝聚的缺失会导致转录机器被显著且自发性地招募，进而引发基因表达的非计划性起始。这其中包括诱导型转录程序的激活，即便在缺乏相关刺激（如GAL系统）的情况下也可发生。值得注意的是，这种紊乱的基因表达会在有丝分裂退出后持续存在。因此，我们揭示了有丝分裂染色体凝聚的全新功能：重置转录组（transcriptome），以阻止基因表达发生偏移，并在间期维持转录稳态。