CENPA as a reader of m6A-modified centromeric RNA to ensure centromere integrity in cancer cells [ChIRP-seq]
Maintaining centromere integrity is crucial for genome stability and proper chromosome segregation during mitosis. CENPA, a conserved histone H3 variant, is localized at the centromeres and plays an essential role in preserving centromere integrity and function. However, the mechanisms that retain CENPA at centromeres remain an enigma. In this study, we identified CENPA as an m6A reader of centromeric RNA (cenRNA), which is essential for its centromeric localization and function in maintaining centromere stability. We discovered a higher level of m6A modification on cenRNA in cancerous cells compared to normal cells. CENPA preferentially binds the cenRNAs with m6A modification, which stabilizes its localization in centromeric regions during the S phase of the cell cycle. We then identified two residues in CENPA responsible for m6A recognition. Mutations in these CENPA residues or removal of m6A on cenRNAs leads to the loss of centromere-bound CENPA during the S phase, thereby resulting in abnormal chromosome separation during mitosis and increased genomic instability. Consequently, this impairment in centromere integrity hindered cancer cell proliferation and tumor growth. Our findings unveiled a novel m6A reading mechanism by CENPA that epigenetically governs centromere integrity in cancer cells, providing potentially new targets for cancer therapy. Overall design: To strengthen the potential link between centromere RNA (cenRNA) methylation and centromere regions, we applied chromatin isolation by RNA purification (ChIRP) to cenRNA followed by high-throughput sequencing in both control and METTL3 knockdown A375 cells.