Rad9 protects cells from topoisomerase poison-induced cell death

A1 Journal article (refereed)

Internal Authors/Editors

Publication Details

List of Authors: Loegering D, Arlander SJH, Hackbarth J, Vroman BT, Roos-Mattjus P, Hopkins KM, Lieberman HB, Karnitz LM, Kaufmann SH
Publication year: 2004
Journal: Journal of Biological Chemistry
Journal acronym: J BIOL CHEM
Volume number: 279
Issue number: 18
Start page: 18641
End page: 18647
Number of pages: 7
ISSN: 0021-9258
eISSN: 1083-351X


Previous studies have suggested two possible roles for Rad9 in mammalian cells subjected to replication stress or DNA damage. One model suggests that a Rad9-containing clamp is loaded onto damaged DNA, where it participates in Chk1 activation and subsequent events that contribute to cell survival. The other model suggests that Rad9 translocates to mitochondria, where it triggers apoptosis by binding to and inhibiting Bcl-2 and Bcl-x(L). To further study the role of Rad9, parental and Rad9 -/- murine embryonic stem (ES) cells were treated with camptothecin, etoposide, or cytarabine, all prototypic examples of three classes of widely used anticancer agents. All three agents induced Rad9 chromatin binding. Each of these agents also triggered S-phase checkpoint activation in parental ES cells, as indicated by a caffeine-inhibitable decrease in [H-3] thymidine incorporation into DNA and Cdc25A down-regulation. Interestingly, the ability of cytarabine to activate the S-phase checkpoint was severely compromised in Rad9-/- cells, whereas activation of this checkpoint by camptothecin and etoposide was unaltered, suggesting that the action of cytarabine is readily distinguished from that of classical topoisomerase poisons. Nonetheless, Rad9 deletion sensitized ES cells to the cytotoxic effects of all three agents, as evidenced by enhanced apoptosis and diminished colony formation. Collectively, these results suggest that the predominant role of Rad9 in ES cells is to promote survival after replicative stress and topoisomerase-mediated DNA damage.

Last updated on 2020-07-07 at 06:24