http://www.ncbi.nlm.nih.gov/pubmed/19903823


J Biol Chem. 2009 Nov 10. [Epub ahead of print]

Large T antigen promotes JC virus replication in G2-arrested cells by inducing ATM- and ATR-mediated G2 checkpoint signaling.
Orba Y, Suzuki T, Makino Y, Kubota K, Tanaka S, Kimura T, Sawa H.

Hokkaido University, Japan;

Large T antigen (TAg) of the human polyomavirus JC virus (JCV) possesses DNA binding and helicase activities, which, together with various cellular proteins, are required for replication of the viral genome. We now show that JCV-infected cells expressing TAg accumulate in G2 phase of the cell cycle as a result of the activation of ATM- and ATR-mediated G2 checkpoint pathways. Transient transfection of cells with a TAg expression vector also induced G2 checkpoint signaling and G2 arrest. Analysis of TAg mutants with different subnuclear localizations suggested that the association of TAg with cellular DNA contributes to the induction of G2 arrest. Abrogation of G2 arrest by inhibition of ATM and ATR, Chk1, and Wee1 suppressed JCV genome replication. In addition, abrogation of G2-M transition by Cdc2 depletion disabled Wee1 depletion-induced suppression of JCV genome replication, suggesting that JCV replication is facilitated by G2 arrest resulting from G2 checkpoint signaling. Moreover, inhibition of ATM and ATR by caffeine suppressed JCV production. The observation that oligodendrocytes productively infected with JCV in vivo also undergo G2 arrest suggests that G2 checkpoint inhibitors such as caffeine are potential therapeutic agents for JCV infection.