Cell division requires RNA eviction from condensing chromosomes

JA Sharp, C Perea-Resa, W Wang, MD Blower - Journal of Cell Biology, 2020 - rupress.org
JA Sharp, C Perea-Resa, W Wang, MD Blower
Journal of Cell Biology, 2020rupress.org
During mitosis, the genome is transformed from a decondensed, transcriptionally active state
to a highly condensed, transcriptionally inactive state. Mitotic chromosome reorganization is
marked by the general attenuation of transcription on chromosome arms, yet how the cell
regulates nuclear and chromatin-associated RNAs after chromosome condensation and
nuclear envelope breakdown is unknown. SAF-A/hnRNPU is an abundant nuclear protein
with RNA-to-DNA tethering activity, coordinated by two spatially distinct nucleic acid–binding …
During mitosis, the genome is transformed from a decondensed, transcriptionally active state to a highly condensed, transcriptionally inactive state. Mitotic chromosome reorganization is marked by the general attenuation of transcription on chromosome arms, yet how the cell regulates nuclear and chromatin-associated RNAs after chromosome condensation and nuclear envelope breakdown is unknown. SAF-A/hnRNPU is an abundant nuclear protein with RNA-to-DNA tethering activity, coordinated by two spatially distinct nucleic acid–binding domains. Here we show that RNA is evicted from prophase chromosomes through Aurora-B–dependent phosphorylation of the SAF-A DNA-binding domain; failure to execute this pathway leads to accumulation of SAF-A–RNA complexes on mitotic chromosomes, defects in metaphase chromosome alignment, and elevated rates of chromosome missegregation in anaphase. This work reveals a role for Aurora-B in removing chromatin-associated RNAs during prophase and demonstrates that Aurora-B–dependent relocalization of SAF-A during cell division contributes to the fidelity of chromosome segregation.
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