RAD18 activates the G2/M checkpoint through DNA damage signaling to maintain genome integrity after ionizing radiation exposure

• Published in: PloS one Vol. 10; no. 2; p. e0117845
• Main Authors: Sasatani, Megumi, Xu, Yanbin, Kawai, Hidehiko, Cao, Lili, Tateishi, Satoshi, Shimura, Tsutomu, Li, Jianxiang, Iizuka, Daisuke, Noda, Asao, Hamasaki, Kanya, Kusunoki, Yoichiro, Kamiya, Kenji
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 12.02.2015; Public Library of Science (PLoS)
• Subjects: Animals; Apoptosis - genetics; Apoptosis - radiation effects; Biology; Cell cycle; Cell death; Cell Line; Cell survival; Deoxyribonucleic acid; DNA; DNA damage; DNA Damage - radiation effects; DNA repair; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Double-strand break repair; Exposure; G2 Phase Cell Cycle Checkpoints - radiation effects; Genomes; Genomic Instability - radiation effects; Genomics; Histones - metabolism; Humans; Integrity; Ionizing radiation; Medicine; Mice; Mice, Knockout; Micronuclei; Micronuclei, Chromosome-Defective - radiation effects; Oncology; Proliferating cell nuclear antigen; Proteins; Radiation; Radiation damage; Radiation effects; Radiation Tolerance - genetics; Radiation, Ionizing; Recruitment; Replication; Replication forks; Signal transduction; Signal Transduction - radiation effects; Signaling; Thymocytes - metabolism; Thymocytes - radiation effects; Ubiquitin; Ubiquitin-protein ligase; Ubiquitin-Protein Ligases; Japan
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0117845

The ubiquitin ligase RAD18 is involved in post replication repair pathways via its recruitment to stalled replication forks, and its role in the ubiquitylation of proliferating cell nuclear antigen (PCNA). Recently, it has been reported that RAD18 is also recruited to DNA double strand break (DSB) sites, where it plays novel functions in the DNA damage response induced by ionizing radiation (IR). This new role is independent of PCNA ubiquitylation, but little is known about how RAD18 functions after IR exposure. Here, we describe a role for RAD18 in the IR-induced DNA damage signaling pathway at G2/M phase in the cell cycle. Depleting cells of RAD18 reduced the recruitment of the DNA damage signaling factors ATM, γH2AX, and 53BP1 to foci in cells at the G2/M phase after IR exposure, and attenuated activation of the G2/M checkpoint. Furthermore, depletion of RAD18 increased micronuclei formation and cell death following IR exposure, both in vitro and in vivo. Our data suggest that RAD18 can function as a mediator for DNA damage response signals to activate the G2/M checkpoint in order to maintain genome integrity and cell survival after IR exposure.