Mitotic transcription and waves of gene reactivation during mitotic exit
AbstractGene expression during mitosis
During mitosis, long-range interactions within chromosomes are lost, and many enhancers become inactive. It is generally thought that gene expression is silent at this time. However, transcription must be reactivated when cells reenter the cell cycle in order to maintain cell identity. Palozola et al. used a sensitive nascent RNA labeling and sequencing method to reveal low-level transcription of many genes in mitosis. Upon mitotic exit, the amplitude of gene expression was reestablished with basic cell functions prioritized over cell-specific genes. Thus, transcription itself may retain gene expression patterns through mitosis.Gene expression during mitosis
Science, this issue p. 119Gene expression during mitosis
Although the genome is generally thought to be transcriptionally silent during mitosis, technical limitations have prevented sensitive mapping of transcription during mitosis and mitotic exit. Thus, the means by which the interphase expression pattern is transduced to daughter cells have been unclear. We used 5-ethynyluridine to pulse-label transcripts during mitosis and mitotic exit and found that many genes exhibit transcription during mitosis, as confirmed with fluorescein isothiocyanate-uridine 5′-triphosphate labeling, RNA fluorescence in situ hybridization, and quantitative reverse transcription polymerase chain reaction. The first round of transcription immediately after mitosis primarily activates genes involved in the growth and rebuilding of daughter cells, rather than cell type-specific functions. We propose that the cell's transcription pattern is largely retained at a low level through mitosis, whereas the amplitude of transcription observed in interphase is reestablished during mitotic exit.