DNA topoisomerase II promotes N6-adenosine mRNA methylation [ChIPseq]

Topoisomerase II (TOP2) is an enzyme that regulates of DNA topology, primarily by removing DNA supercoiling. This function is crucial during transcription, as the movement of RNA polymerase II (RNAPII) generates torsional stress. However, the specific role of TOP2 in the regulation of gene expression remains to be fully elucidated, as both TOP2 inhibitors and poisons have been shown to upregulate specific genes. In this study, we show that TOP2 poisoning negatively affects transcription elongation of genes repressed at the level of promoter-proximal pausing. Importantly, this effect is counteracted by a defective mRNA N6-adenosine methylation (m6A) which results in altered mRNA turnover and pre-mRNA splicing. We propose that TOP2 serves a dual function, supporting the maintenance of basal transcription elongation while simultaneously promoting m6A modification in pre-mRNAs to reduce the overall gene expression output. Overall design: Chromatin immunoprecipitation DNA-sequencing (ChIP-seq) for RBP1, the largest subunit of RNA polymerase II, and METTL3 in serum-starved RPE-1 cells after 50 µM etoposide treatment.