Dynamic behavior of DNA topoisomerase II? in response to DNA double-strand breaks.

ABSTRACT: DNA topoisomerase II (Topo II) is crucial for resolving topological problems of DNA and plays important roles in various cellular processes, such as replication, transcription, and chromosome segregation. Although DNA topology problems may also occur during DNA repair, the possible involvement of Topo II in this process remains to be fully investigated. Here, we show the dynamic behavior of human Topo II? in response to DNA double-strand breaks (DSBs), which is the most harmful form of DNA damage. Live cell imaging coupled with site-directed DSB induction by laser microirradiation demonstrated rapid recruitment of EGFP-tagged Topo II? to the DSB site. Detergent extraction followed by immunofluorescence showed the tight association of endogenous Topo II? with DSB sites. Photobleaching analysis revealed that Topo II? is highly mobile in the nucleus. The Topo II catalytic inhibitors ICRF-187 and ICRF-193 reduced the Topo II? mobility and thereby prevented Topo II? recruitment to DSBs. Furthermore, Topo II? knockout cells exhibited increased sensitivity to bleomycin and decreased DSB repair mediated by homologous recombination (HR), implicating the role of Topo II? in HR-mediated DSB repair. Taken together, these results highlight a novel aspect of Topo II? functions in the cellular response to DSBs.

SUBMITTER: Morotomi-Yano K 

PROVIDER: S-EPMC6037730 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature