Cell division requires RNA eviction from condensing chromosomes.

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• During mitosis, the genome transitions from an active to an inactive state.
• Regulation of nuclear and chromatin-associated RNAs after nuclear envelope breakdown is poorly understood.

Purpose of the Study:

• To investigate the mechanism of RNA regulation during mitosis.
• To elucidate the role of SAF-A/hnRNPU in managing chromatin-associated RNAs during cell division.

Main Methods:

• Investigated the role of SAF-A/hnRNPU and its interaction with RNA during mitosis.
• Utilized biochemical assays to study protein phosphorylation and RNA eviction.
• Observed chromosome dynamics and segregation fidelity in cells with altered SAF-A/hnRNPU function.

Main Results:

• SAF-A/hnRNPU's RNA-to-DNA tethering activity is regulated by Aurora-B dependent phosphorylation.
• Phosphorylation of SAF-A's DNA-binding domain mediates RNA eviction from prophase chromosomes.
• Failure in this process results in SAF-A-RNA complexes on mitotic chromosomes, leading to chromosome misalignment and missegregation.

Conclusions:

• Aurora-B plays a critical role in removing chromatin-associated RNAs during prophase.
• Aurora-B-dependent relocalization of SAF-A is vital for maintaining chromosome segregation fidelity during cell division.